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
2000-05-24
2002-05-14
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...
C526S113000, C526S114000, C526S118000, C526S119000, C526S201000, C526S124300, C526S160000, C526S943000
Reexamination Certificate
active
06388017
ABSTRACT:
FIELD OF INVENTION
This invention is related to the field of processes for producing a polymer composition.
BACKGROUND OF THE INVENTION
The production of polymers is a multi-billion dollar business. This business produces billions of pounds of polymers each year. Millions of dollars have been spent on developing technologies that can add value to this business.
Increasing production of polymers from polymerization processes is an important area of polymer research. In addition, discovering new polymer blends having superior properties also is a continuing research goal. Specifically, improving optical properties, such as haze and gloss, of such polymers blends blown into film, also is an important goal of polymer research since film is often used in packaging and other applications.
It is an object of this invention to provide a process for producing a polymer composition.
It is another object of this invention to provide the polymer composition.
It is another object of this invention to provide a process for increasing the production of polymers from polymerization processes by increasing the bulk density of a narrow molecular weight distribution base polymer by incorporating a high molecular weight polymer component with the narrow molecular weight distribution base polymer to produce a polymer composition.
It is another object of this invention to provide a process for increasing the clarity of blown film produced from a narrow molecular weight distribution base polymer by incorporating a high molecular weight polymer component with the narrow molecular weight distribution base polymer to produce a polymer composition.
SUMMARY OF THE INVENTION
In accordance with one embodiment of this invention, a process for producing a polymer composition is provided. The process comprises incorporating a narrow molecular weight distribution base polymer and a high molecular weight polymer component to produce the polymer composition;
wherein the base polymer is an ethylene polymer having a Mw/Mn less than about 5 and a melt flow index from about 0.2 g/10 min to about 20 g/10 min; and
wherein the high molecular weight polymer component has a molecular weight distribution such that at least a substantial portion of its molecules have a molecular weight of greater than one million, the component being incorporated is in an amount to give about 0.1 to about 10% by weight, based on the total weight of said polymer composition, of the molecules having a molecular weight greater than one million.
These objects, and other objects, will become more apparent to those with ordinary skill in the art after reading this disclosure.
DETAILED DESCRIPTION OF THE INVENTION
A process is provided for producing a polymer composition. The process comprises incorporating a narrow molecular weight distribution base polymer and a high molecular weight polymer component. The narrow molecular weight distribution base polymer is hereinafter referred to as a “base polymer”. When the base polymer is incorporated with the high molecular weight polymer component, the bulk density of the base polymer is increased, thereby, increasing the production rate. The bulk density of the polymer composition can be increased by about 10% to about 40% over the bulk density of the base polymer. In order to achieve the bulk density increase, the high molecular weight polymer component must be incorporated with the base polymer while the base polymer is produced in a polymerization zone.
Another benefit of incorporating the base polymer and the high molecular weight polymer component is to increase the clarity of blown film produced from the base polymer. In order to achieve this clarity increase, the incorporation of the high molecular weight polymer component can be accomplished either while the base polymer is being produced in the polymerization zone or after the base polymer and high molecular weight polymer component have been produced separately. For example, the base polymer and high molecular weight polymer component can be blended together to produce the polymer composition. The haze of the polymer composition can be decreased by about 5% to as much as about 60% over the haze of the base polymer, and the gloss of the polymer composition can be increased by about 10 to about 40% over the gloss of the base polymer.
The base polymer is defined as the narrow molecular weight polymer before the high molecular weight polymer component is added to produce the polymer composition. The base polymer can be any narrow molecular weight distribution ethylene polymer, either a homopolymer or copolymer, such as, for example, ethylene-hexene copolymers. The base polymer has a Mw(weight average molecular weight)/Mn (number average molecular weight) of less than about 5.0. Preferably, Mw/Mn of the base polymer is less than about 4.0, and most preferably, Mw/Mn of the base polymer is less than 3.0.
Base polymers can be produced from any catalyst known in the art to produce narrow molecular weight distribution polymers. For example, metallocene catalysts of various types, such as described in U.S. Pat. Nos. 5,436,305; 5,610,247; and 5,627,247, herein incorporated by reference, can be used to produce the base polymer. Ziegler catalysts containing magnesium and titanium halides, such as described in U.S. Pat. Nos. 5,275,992; 5,179,178; 5,275,992; 5,237,025; 5,244,990; and 5,179,178, herein incorporated by reference, can also be used. Chromium catalysts as described for example in U.S. Pat. Nos. 3,887,494; 3,119,569; 3,900,457; 4,981,831; 4,364,842; and 4,444,965, herein incorporated by reference, also can be utilized to produce the base polymer. Preferably, the base polymer is produced from metallocene catalyst. Since these catalysts are well known to produce a narrow molecular weight distribution polymer, are very active, and often are very efficient for the incorporation of comonomer.
The base polymer can be an ethylene homopolymer or preferably, a copolymer of ethylene and at least one other alpha-olefin, such as 1-hexene, 1-butene, or 1-octene. Most preferably, the base polymer is an ethylene-hexene copolymer.
Generally, the density of the base polymer is in a range of about 0.900 g/cc to about 0.975 g/cc. Preferably, the density of the base polymer is in a range of about 0.910 g/cc to about 0.940 g/cc, and most preferably, from 0.915 g/cc to 0.93 g/cc. Generally, the base polymer has a melt flow index in a range from about 0.2 g/10 min to about 20 g/10 min. Preferably, the base polymer has a melt flow index in a range from about 0.5 g/10 min to about 10 g/10 min, and most preferably from 0.8 g/10 min to 5.0 g/10 min.
The high molecular weight polymer component can be produced from most any known catalyst system, whether the high molecular weight polymer component is produced simultaneously with the base polymer in the polymerization zone, or separately and blended later. Suitable catalysts for production of the high molecular weight polymer component include, but are not limited to, Ziegler catalysts based on titanium halides, zirconium halides, zirconium alkyls, chromium oxide catalysts, metallocene catalysts, and mixtures thereof.
The high molecular weight polymer component has a molecular weight distribution, such that, a substantial portion of its molecules have a molecular weight greater than one million. Generally, the high molecular weight polymer component being incorporated is in an amount to give about 0.1% to about 10% by weight, based on the total weight of the polymer composition, of the molecules having a molecular weight greater than one million. Preferably, the high molecular weight polymer component being incorporated is in an amount to give about 0.5% to about 5% by weight, based on the total weight of the polymer composition, of the molecules having a molecular weight greater than one million, most preferably, 1% to 3% by weight.
It is not imperative that the additional high molecular weight polymer component be pure. For example, a high molecular weight polymer component which also contains a substantial amount of polyme
Benham Elizabeth A.
Collins Kathy S.
Eaton Anthony P.
Kennedy Shawn R.
Krishnaswamy Rajendra K.
Owen Polly C.
Phillips Petroleum Company
Rabago R.
Wu David W.
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