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...
Patent
1985-03-29
1986-12-02
Lilling, Herbert J.
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...
524424, 524426, 524433, 524436, 524437, 524445, 524451, 524505, C08L 5300, C08L 2316, C08K 300, C08K 514
Patent
active
046265651
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to a process for preparing polypropylene-base resin compositions having excellent low-temperature impact resistance, high molding fluidity, superb paintability and high stiffness.
2. Background Art
Although polypropylene resins have heretofore been used widely in various fields because of their excellent physical properties such as low specific gravity, high stiffness, and superb chemical and heat resistance, they are accompanied by a drawback in that they have poor impact resistance at low temperatures. With a view toward overcoming this drawback, it has been practiced to subject propylene to copolymerization with ethylene or to blend a rubber-like substance such as an ethylene-propylene copolymer or polyethylene with polypropylene. In addition, it is also commonly practiced to improve their stiffness, heat resistance, dimensional stability, paintability and the like by incorporating a variety of fillers in polypropylene resins.
Given these conditions, it is, however, required for polypropylene resins to fulfill such mutually contradictory properties as high stiffness, high heat resistance, easy paintability and high molding fluidity in combination with high impact resistance. Moreover, each of the above properties is required at a high level.
A variety of improvements have been proposed for the above requirements to date. Most of these proposals are, however, insufficient to meet and balance the high degrees of physical properties required. Therefore, it may be required in many instances to add a rubber component, fillers and so on at higher concentrations to polypropylene resins, resulting in increased costs.
DISCLOSURE OF THE INVENTION
An object of this invention is to provide a preparation process for inexpensive polypropylene-base resin compositions having excellent low-temperature impact resistance, high molding fluidity and high stiffness.
Another object of this invention is to provide a preparation process for polypropylene-base resin compositions suitable for use in the production of large moldings such as automobile bumpers, fenders and body sidemembers.
The present invention thus provides the following preparation process for polypropylene-base resin compositions:
A process for preparing polypropylene-base resin compositions, which process comprises heating at a temperature of 170.degree. C.-280.degree. C. a mixture containing:
(a) a crystalline ethylene-propylene block copolymer having an ethylene content of 7-30 wt. % and having a portion of 65 wt. % or more insoluble in boiling n-heptane;
(b) an ethylene-propylene copolymer rubber having a propylene content of 40-65 wt. % and a Mooney viscosity of 15-80 at 100.degree. C.;
(c) an inorganic filler having particle sizes of 6 .mu.m or smaller; and
(d) an organic peroxide, said components (a), (b), (c) and (d) being contained in amounts of 65-95 wt. %, 35-5 wt. %, 2-25 wt. % and 0.001-0.5 wt. %, respectively, all based on the total amount of components (a) and (b).
BEST MODE FOR CARRYING OUT THE INVENTION
The crystalline ethylene-propylene block copolymer useful in the practice of this invention has an ethylene content of 7-30 wt. % and having a portion of 65 wt. % or more insoluble in boiling n-heptane. If the above ethylene content is less than 7 wt. %, the paintability and impact resistance of the resulting molding is reduced. On the other hand, any ethylene content greater than 30 wt. % reduces the modulus of flexural elasticity of the resulting molding. Thus, it is preferable not to use the crystalline ethylene-propylene block copolymer in any amounts outside the above range.
The ethylene-propylene copolymer rubber, which is also useful in the practice of this invention, is limited to those having propylene contents of 40-65 wt. % and Mooney viscosities of 15-80 at 100.degree. C. If the propylene content is less than 40 wt. % in the above ethylene-propylene copolymer rubber, the resulting molding has poor appearance and reduced low-temperature impact resistance. On the other hand,
REFERENCES:
patent: 4363885 (1982-12-01), Fukii et al.
patent: 4480065 (1984-10-01), Kawai et al.
Derwent Abst. 41211b/22 Ube Ind J54048847 4-1979.
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Derwent Abst. 83-822910/47 J58173145 Tokuyama 10-1983.
Derwent Abst. 83-780668/40 J58145746 Tokuyama 8-1983.
Derwent Abst. 57634 K/24 J58076444 Mitsubishi 5-1983.
Abe Masaru
Hayashi Shigeru
Kawai Yoichi
Sekiguchi Katsumi
Yoshihara Akio
Lilling Herbert J.
Mitsui Toatsu Chemicals Incorporated
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