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
2000-02-07
2004-11-30
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S088000, C525S089000, C528S396000, C524S494000, C524S394000, C524S127000, C524S349000, C524S351000, C524S312000, C524S313000, C524S086000, C524S091000
Reexamination Certificate
active
06825280
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a block copolymer comprising polypropylene and an ethylene-propylene copolymer, and more particularly to a block copolymer having good impact resistance.
The present invention further relates to a novel propylene polymer composition. More particularly, the present invention relates to a propylene polymer composition which has an excellent balance between rigidity and warpage properties, an excellent balance among hot processing properties, weathering resistance and low bleeding, and an excellent balance between antistatic properties and low bleeding, and a propylene resin composition which has an excellent balance among rigidity, impact resistance (particularly low-temperature impact resistance) and heat resistance and is useful as a material for injection molding, extrusion, or blow molding.
BACKGROUND ART
Propylene resin materials, such as polypropylene, have excellent moldability and rigidity and, at the same time, have excellent recycling properties and heat resistance. By virtue of these excellent properties, the propylene resin materials have been used in various types of molding, and, as with other resins such as vinyl chloride resin and polystyrene, have been utilized in a wide variety of applications, such as automobiles, domestic electric appliances, and industrial materials. These resin materials are generally molded by injection molding, extrusion, blow molding or the like, and the molded products thus obtained are utilized in the above applications.
In some cases, nucleating agents are added to a conventional polypropylene produced in the presence of a Ziegler catalyst to improve the rigidity. This, however, had a drawback that warpage is likely to occur in the product. An attempt to produce materials having no significant warpage has led to a limitation on the amount of the nucleating agent added. This has made it impossible to produce materials satisfying both the rigidity and low warpage requirements. Further, processing sometimes causes deterioration due to thermal oxidation, such as burning or increased MFR. This problem also has not hitherto been solved in the art. In some cases, light stabilizers are added to conventional polypropylene produced in the presence of a Ziegler catalyst in order to impart weathering resistance to the polypropylene. In this case, the light stabilizers are bled on the product, and this deteriorates the appearance of the product. On the other hand, an attempt to provide materials, which are less likely to cause bleeding, leads to a limitation on the type and amount of the light stabilisers added. For this reason, resin materials satisfying both the weathering resistance and low bleeding property requirements have not been proposed in the art.
Further, in the case of polypropylene produced in the presence of a Ziegler catalyst, antistatic agents are sometimes added from the viewpoint of imparting antistatic properties to the polypropylene. In this case, however, the antistatic agents are bled on the product, and this deteriorates the appearance of the product. On the other hand, an attempt to provide materials, which are less likely to cause bleeding, leads to a limitation on the type and amount of the antistatic agent added. For this reason, resin materials satisfying both the antistatic property and low bleeding property requirements have not been proposed in the art.
In recent years, there is a demand for a reduction in thickness and a reduction in weight of molded products, such as injection molded products, from the viewpoints of resource saving and energy saving. Also for polypropylene molding materials, various proposals have been made to improve the balance between rigidity and impact resistance to realize a reduction in thickness and a reduction in weight of the molded products.
For example, the use of a block copolymer produced by stepwise polymerizing propylene with ethylene or other olefin(s) to reduce the thickness and to reduce the weight is already known in the art. Further, a propylene block copolymer produced by polymerization in the presence of a catalyst system comprising a metallocene compound and a co-catalyst has recently been proposed as a polypropylene having improved low-temperature impact resistance and other properties (Japanese Patent Laid-Open Nos. 337308/1992, 202152/1993, and 206921/1994, Publication No. 510491/1996 of the Translation of International Patent Application, WO 95/27740, WO 95/27741 and the like). Further, the applicant of the present application also has proposed improved methods in the above catalyst system using a specific carrier and a specific polymerization method (Japanese Patent Laid-Open Nos. 172414/1994, 287257/1994, and 27237/1996).
Propylene block copolymers produced by these methods, however, do not always have a satisfactory balance among rigidity, impact strength (particularly low-temperature impact strength) and/or heat resistance, and a further improvement in this balance has been desired in the art.
Accordingly, it is an object of the present invention to provide a block copolymer having an excellent balance between rigidity and impact resistance, a propylene polymer composition having an excellent balance between rigidity and low warpage properties and having excellent resistance to deterioration caused by thermal oxidation during processing, weathering resistance, antistatic properties, and low bleeding properties, and a propylene resin composition which can easily yield molded products having an excellent balance among rigidity, impact resistance (particularly low-temperature impact resistance) and/or heat resistance.
DISCLOSURE OF THE INVENTION
Under the above circumstances, the present inventors have made extensive and intensive studies with a view to improving the rigidity and the impact strength and the balance among warpage properties, resistance to deterioration caused by thermal oxidation during processing, weathering resistance, antistatic properties, and low bleeding properties of polypropylene, and, as a result, have found that the use of a propylene block copolymer having a specific polymer structure and, in addition, the incorporation of specific additives can provide propylene polymer compositions having excellent rigidity and low warpage properties, resistance to deterioration caused by thermal oxidation, weathering resistance, antistatic properties, and low bleeding properties. This has led to the completion of the present invention. Further, as a result of extensive and intensive studies, the present inventors have found that the use of a propylene polymer having a specific polymer structure and specific additives can provide molded products having an excellent balance among rigidity, impact resistance (particularly low-temperature impact resistance) and heat resistance, which has led to the completion of the present invention.
Thus, according to the present invention, there are provided a propylene block copolymer consisting essentially of the following blocks (a) and (b) and having a melt flow rate (molecular weight index of polymer) of 0.1 to 200 g/10 min (this propylene block copolymer being hereinafter referred to simply as a “propylene block copolymer”), and a propylene polymer composition comprising: 100 parts by weight of the above propylene block copolymer; and 0.001 to 1 part by weight of at least one metal salt selected from the group consisting of 1) metal salts of aromatic phosphoric acids and 2) metal salts of aromatic or alicyclic carboxylic acids,
0.001 to 1 part by weight of at least one compound selected from the group consisting of 3) aromatic phosphoric ester compounds having a melting point of 50° C. or above and 4) hindered phenolic compounds,
0.001 to 1 part by weight of at least one compound selected from the group consisting of 5) hindered amine compounds, 6) triazole compounds, 7) benzophenone compounds, and 8) benzoate compounds, or
0.001 to 1 part by weight of at least one compound selected from the group consisting of 9) fatty acid glycerol esters and 10) fatty acid diethanol
Fujita Yuuji
Hayakawa Yu
Kosegaki Kimiho
Maruyama Yasuo
Ogasawara Tsuyoshi
Japan Polychem Corporation
Lee Rip A
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Wu David W.
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