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
1998-07-07
2002-08-20
Pyon, Harold (Department: 1772)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C428S035700, C525S320000
Reexamination Certificate
active
06437048
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a plastic molded product using a resin composition with polypropylene as the main component. More precisely, the present invention relates to a plastic molded product using a resin composition with polypropylene as the main component having a high melt strength and a high crystallization temperature.
BACKGROUND OF THE INVENTION
Polypropylene is widely used in all molding fields, because its superior mechanical qualities and resistance against chemicals are conveniently combined with high economic efficiency. However, its melt strength and its crystallization temperature are low, so that not only is it of inferior moldability in molding fields such as blow molding, expansion molding and extrusion molding, but also there are limits to the production rate with respect to most other molding methods as well.
To raise the melt strength and the crystallization temperature of polypropylene, methods have been disclosed wherein molten polypropylene reacts with an organic peroxide and a crosslinking agent (see for example Publication of Unexamined Patent Application (Tokkai) No. Sho 59-93711 and Tokkai No. Sho 61-152754), and a method has been disclosed wherein half-crystalline polypropylene reacts in the absence of oxygen with a peroxide having a low dissolution temperature, so that a polypropylene having a free end long chain branching and not comprising gel is produced (Tokkai No. Hei 2-298536).
As another method to improve the dissolving viscoelastic properties such as the melt strength, a composition combining a polyethylene and a polypropylene with differing intrinsic viscosity and molecular weight, and a method for producing such a composition by multistep polymerization, have been proposed.
For example, in Published Examined Patent Application (Tokko) No. Sho 61-28694, a method has been disclosed wherein 2-30 weight parts of ultrahigh molecular weight polypropylene are added to 100 weight parts of regular polypropylene and extrusion molding is performed in a temperature range above the melting point and below 210° C. In Tokko No. Hei 1-12770, an extruded sheet with two polypropylene components of different molecular weights and an intrinsic viscosity ratio of at least 2, which is obtained by a multistep polymerization method, has been disclosed. In Tokko No. Sho 62-61057, a method for melt kneading and a method for multistep polymerization of a polyethylene composition consisting of three kinds of polyethylenes with differing viscosity and average molecular weight, comprising 1-10 wt % of a high viscosity, average molecular weight polyethylene have been disclosed. Tokko No. Hei 5-79683 discloses a polymerization method for polyethylene, wherein between 0.05 and 1 wt % of an ultrahigh molecular weight polyethylene having in intrinsic viscosity of not less than 20 dl/g is polymerized by multistep polymerization using a high activity titanium vanadium solid catalyst component. Tokko No. Hei 7-8890 discloses a polymerization method for polyethylene, wherein 0.1-5 wt % of an ultrahigh molecular weight polyethylene having an intrinsic viscosity of not less than 15 dl/g is polymerized by multistep polymerization in specially arranged curing units using a high activity titanium catalyst component preliminarily polymerized with 1-butene and 4-methyl-1-pentene.
In Tokkai No. Hei 5-222122, a method is disclosed for producing polypropylene having high melt strength, by polymerization of propylene using a preliminary polymerization catalyst that results from the preliminary polymerization of ethylene and a polyene compound with a support type solid catalyst comprising titanium and an organic aluminium compound catalyst. Tokkai No. Hei 4-55410 discloses a method for producing ethylene &agr;-olefin copolymer having high melt strength by us ing a preliminary polymerization catalyst comprising ethylene and a polyethylene with an intrinsic viscosity of not less than 20 dl/g, wherein preliminary polymerization is performed exclusively in the ethylene by using the same catalyst as in Tokkai No. Hei 5-222122.
Although it has to be acknowledged that in the various components proposed in the prior art as described above and in the production processes belonging thereto the melt strength has been somewhat increased, many aspects such as a residual odor caused by the crosslinking agent, the crystallization temperature and the heat stability have to be improved.
Moreover, in a multistep polymerization that incorporates a production process of high molecular weight polyolefin into a main polymerization of a regular polypropylene (co)polymerization process, the precise control of the polypropylene (co)polymerization for formation of a small amount of high molecular weight olefin is difficult, and a low polymerization temperature is necessary for formation of the polypropylene with a sufficiently large molecular weight, which lowers the rate of production for the final polypropylene composition. Thus, improvement of the process is necessary.
In the method for preliminarily polymerizing a polyene compound, it is necessary to prepare the polyene compound separately. In the method for preliminarily polymerizing polyethylene, the dispersibility of the preliminarily polymerized ethylene in a finally obtained polyolefin compound is not uniform, so that from the viewpoint of stability of the polyolefin compound, improvement of the process is required.
As has been pointed out above, the problems of low melt strength and low crystallization temperature of polypropylene, as well as the problems of odor and heat stability are inherent in the prior art, so that an improvement of polypropylene plastic molded products is strongly desired.
SUMMARY OF THE INVENTION
In order to solve the problems of the prior art, it is a first object of the present invention to provide a plastic molded product using a polypropylene resin composition, which has high melt strength and high crystallization temperature, as a main component.
A second object of the present invention is to provide a resin foam having uniformly fine foaming cells (bubbles) and a high expansion ratio using a polypropylene composition.
A third object of the present invention is to provide a sheet or film plastic using a polypropylene composition having high melt strength and excellent moldability in a thermoforming, vacuum forming, pressure forming and the like.
A fourth object of the present invention is to provide a hollow plastic article using a polypropylene composition with high melt strength and high crystallization temperature, which has excellent moldability with regard to hollow plastic molding, the hollow plastic article having high resistance against drawdown at shock, high production, high stiffness and high stiffness against heat.
A fifth object of the present invention is to provide an injection molded plastic product using a polypropylene composition having high melt strength and high crystallization temperature, which has excellent heat resistance and stiffness.
A sixth object of the present invention is to provide a polypropylene fiber and nonwoven fabric with high melt strength and high crystallization temperature, which has excellent heat resistance and stiffness.
A seventh object of the present invention is to provide a tube-shaped continuous plastic, which does not whiten with impact, has a high impact strength at low temperatures and can be produced with high productivity using high melt strength and high crystallization speed.
In order to achieve the above objects, a plastic molded product of an olefin (co)polymer composition according to the present invention is provided, which comprises:
(a) 0.01-5.0 weight parts of high molecular weight polyethylene, which is an ethylene homopolymer or an ethylene-olefin copolymer containing not less than 50 wt % ethylene units and has an intrinsic viscosity &eegr;
E
in the range of 15-1000 dl/g measured in tetralin at 135° C.; and
(b) 100 weight parts of an olefin (co)polymer which consists of a propylene homopolymer or propylene-olefin copolymer con
Fukazawa Tooru
Ishii Hirohisa
Ito Hiroaki
Kawano Shouji
Kikukawa Shingo
Chisso Corporation
Hon Sow-Fun
Pyon Harold
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