Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1996-10-07
1998-11-24
Smith, Edward J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525270, 526114, 526119, 526943, C08F21016
Patent
active
058408088
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to processes for preparing olefin polymers, and more particularly to processes for preparing olefin polymers having excellent impact strength as well as excellent mechanical strength such as rigidity.
BACKGROUND ART
Crystalline polypropylene has been conventionally known as a polymer having excellent rigidity, heat resistance and surface gloss. Also, a propylene block copolymer containing both of a polypropylene component and a rubber component has been known as a propylene polymer which has more improved impact resistance than the crystalline polypropylene.
The propylene polymers are characterized in that they have small specific gravity and can be easily recycled, so that they have been paid much attention in view of environmental protection and are desired to be applied to more extensive uses.
Therefore, the propylene polymers, particularly crystalline polypropylenes, are desired to be further improved in the impact strength.
For improving the impact strength of the propylene polymers, there have been conventionally known a method of forming a propylene block copolymer as described above and a method of adding a modifier such as polyethylene or a rubber-like material to the crystalline polypropylene so as to form a polypropylene composition. Examples of the rubber-like materials generally known include an amorphous or low-crystalline ethylene/propylene random copolymer (EPR), polyisobutylene and polybutadiene.
In order to improve the impact resistance by adding such rubber-like materials, they need to be added to the polypropylene in a large amount. However, a polypropylene composition containing a large amount of the rubber-like material is markedly deteriorated in the mechanical strength such as rigidity, heat resistance and surface hardness, though the impact resistance is improved.
For this reason, a polypropylene composition, to which an inorganic filler such as talc is also added together with the rubber-like material to thereby impart rigidity, is proposed.
However, the polypropylene composition containing a large amount of the rubber-like material has limitations in the improvement of rigidity given by adding the inorganic filler such as talc, and there is a problem in that the polypropylene composition cannot be applied to such a use as requires high rigidity.
Further, the propylene polymers obtained by the conventional processes do not always show sufficient rigidity and heat resistance depending on circumstances, resulting in limitations in their uses.
Accordingly, now desired is development of processes for preparing olefin polymers, by which propylene polymers having excellent impact strength as well as excellent mechanical strength such as rigidity, moldability and heat resistance can be obtained.
The present invention has been made under such circumstances as described above, and it is an object of the invention to provide processes for preparing olefin polymers, by which olefin polymers having excellent impact strength as well as excellent mechanical strength such as rigidity, moldability and heat resistance can be obtained.
DISCLOSURE OF THE INVENTION
The first process for preparing an olefin polymer according to the invention comprises: propylene and an .alpha.-olefin other than propylene to form a crystalline polypropylene component and (ii) a step of copolymerizing ethylene and an .alpha.-olefin of 3 to 20 carbon atoms to form a low-crystalline or non-crystalline ethylene/.alpha.-olefin copolymer component, in an arbitrary order in the presence of the olefin polymerization catalyst (1) so as to form a propylene block copolymer component, said catalyst (1) comprising: halogen and an electron donor, system, said catalyst (2) comprising: skeleton, and ionic compound; and so as to form a low-crystalline or non-crystalline ethylene/.alpha.-olefin copolymer component.
The second process for preparing an olefin polymer according to the invention comprises: propylene and an .alpha.-olefin other than propylene to form a crystalline polyprop
REFERENCES:
patent: 5322902 (1994-06-01), Schreck et al.
patent: 5589549 (1996-12-01), Govoni et al.
patent: 5605969 (1997-02-01), Tsutsui et al.
Kioka Mamoru
Sugimura Kenji
Mitsui Petrochemical Industries Ltd.
Smith Edward J.
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