Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymerizing in tubular or loop reactor
Reexamination Certificate
1999-07-27
2003-05-27
Pyon, Harold (Department: 1772)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymerizing in tubular or loop reactor
C502S202000, C502S256000, C502S319000, C428S035700, C526S106000, C526S134000, C526S348000
Reexamination Certificate
active
06569960
ABSTRACT:
FIELD OF THE INVENTION
This invention is related to the field of processes that produce polymers, where said polymers comprise polymerized ethylene. The phrase “ethylene polymers” as used in this application includes homopolymers of ethylene, and copolymers of ethylene with another monomer. Particularly, this invention is related to the field of processes that produce ethylene polymers having a broad molecular weight distribution. More particularly, this invention is related to the field of processes that produce ethylene polymers that have low formation of smoke and odor during blow molding.
BACKGROUND OF THE INVENTION
There are many production processes that produce ethylene polymers. Ethylene polymers are utilized in many products, such as, for example, films, coatings, fibers, bottles and pipe. Producers of such ethylene polymers are continuously conducting research to find improved ethylene polymers.
Ethylene polymers with a broad molecular weight distribution generally have excellent processing characteristics such as, for example, high shear ratio, high shear at onset of melt fracture, low weight and die swell, and excellent physical properties such as high environmental stress crack resistance. However, often times, these ethylene polymers can produce smoke and odors when blow molded into manufactures.
This invention provides ethylene polymers having a broad molecular weight distribution and also low formation of smoke and odors during blow molding. Due to these improved properties, these ethylene polymers are ideal for blow molding bottles and other manufactures.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a process to polymerize ethylene, or to copolymerize ethylene with at least one other monomer, to produce ethylene polymers.
It is another object of this invention to provide said ethylene polymers.
It is another object of this invention to provide ethylene polymers having high environmental stress crack resistance and low formation of smoke and odor during blow molding.
It is yet another object of this invention to provide a process to use said ethylene polymers to produce a manufacture.
It is still yet another object of this invention to provide a manufacture comprising said ethylene polymers.
In accordance with this invention, a process is provided, said process comprising polymerizing ethylene, or copolymerizing ethylene with at least one other monomer, wherein said polymerizing is conducted:
in a loop reactor with isobutane as a diluent;
at a temperature in a range of about 200° F. to about 220° F.;
with a catalyst system comprising chromium and a support;
in the presence of at least one trialkylboron;
wherein the chromium is present in a range of about 1% by
weight to about 4% by weight based on the weight of the support;
wherein said support comprises silica and titania;
wherein said support has a surface area of about 400 m
2
/gram to about 800 m
2
/gram and a pore volume of about 1.8 ml/gram to about 4 ml/gram;
wherein the titania is present in a range of about 0.5% by weight to about 3% by weight titanium based on the weight of the support;
wherein said catalyst system is activated at a temperature from about 1000° F. to about 1300° F.;
wherein said trialkylboron is represented by the formula, BR
3
,
where R is an alkyl group of up to 12 carbon atoms.
In another embodiment of this invention, said ethylene polymers are provided.
In yet another embodiment of this invention, a process for using said ethylene polymers to produce a manufacture is provided.
In still another embodiment of this invention, a manufacture is provided comprising said ethylene polymers.
These and other objects of this invention will become more evident from the following description and claims.
DETAILED DESCRIPTION OF THE INVENTION
A process comprising polymerizing ethylene, or copolymerizing ethylene with at least one other monomer is provided. Said “at least one other monomer” can be olefins having from 4 to about 16 carbon atoms per molecule. Suitable monomers, that can be polymerized with ethylene to produce copolymers with excellent properties, can be selected from the group consisting of 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene.
The polymerizing is conducted in a loop reactor process at a temperature in a range of about 200° F. to about 220° F. with isobutane as a diluent. The loop reactor process is well known in the art and is disclosed, for instance, in Norwood, U.S. Pat. No. 3,248,179, the disclosure of which is hereby incorporated by reference.
The polymerizing is conducted using a catalyst system comprising chromium and a support. The chromium can be any suitable chromium compound that facilitates the polymerization of olefins. Suitable examples of chromium compounds include, but are not limited to, chromium nitrate, chromium acetate, chromium trioxide, and mixtures thereof. The amount of chromium present is from about 1% by weight to about 4% by weight. Preferably, the amount of chromium present is from about 1.5% by weight to about 3.5% by weight, most preferably, from 2% by weight to 3% by weight, where such weight percents are based on the weight of the support.
The chromium can be combined with the support in any manner known in the art. Examples of combining the chromium with the support can be found in U.S. Pat. Nos. 3,976,632; 4,248,735; 4,297,460; and 4,397,766; the entire disclosures of which are hereby incorporated by reference.
The term “support” is not meant to be construed as an inert component of the catalyst system. The support used in the catalyst system of this invention comprises (or alternatively, “consists essentially of” or “consists of”) silica and titania. These supports are known in the art and are disclosed in U.S. Pat. Nos. 2,825,721; 3,225,023; 3,226,205; 3,622,521; 3,625,864; 3,780,011; 3,887,494; 3,900,457; 3,947,433; 4,053,436; 4,081,407; 4,151,122; 4,177,162; 4,294,724; 4,296,001; 4,392,990; 4,402,864; 4,405,501; 4,434,243; 4,454,557; 4,735,931; 4,981,831; and 5,037,911, the entire disclosures of which are hereby incorporated by reference. However, it should also be noted that these supports are available commercially from such sources as the W. R. Grace Corporation.
Generally, the amount of titania present is from about 0.5% by weight to about 3% by weight titanium. Preferably, the amount of titania present is from about 0.8% by weight to about 2.6% by weight titanium, most preferably from 0.8% by weight to 1.5% by weight titanium, where such weight percents are based on the weight of the support.
The support has a surface area from about 400 m
2
/gram to about 800 m
2
/gram. Preferably, the support has a surface area from about 450 m
2
/gram to about 700 m
2
/gram, and most preferably, from 500 m
2
/gram to 600 m
2
/gram. Furthermore, the support has a pore volume of from about 1.8 ml/gram to about 4 ml/gram. Preferably, the support has a pore volume of from about 2 to about 3.5 ml/gram, and most preferably, from 2.3 ml/gram to 3 ml/gram.
The catalyst system used in this invention is activated in accordance with any manner known in the art that will contact an oxygen containing ambient with the catalyst system. Suitable examples of this type of procedure can be found in U.S. Pat. Nos. 3,887,494; 3,900,457; 4,053,436; 4,081,407; 4,296,001; 4,392,990; 4,405,501; and 4,981,831, the entire disclosures of which are hereby incorporated by reference. Generally, activation is conducted at a temperature in a range of about 1000° F. to about 1300° F. Preferably, activation is conducted at a temperature in a range of about 1050° F. to about 1250° F., and most preferably, from 1100° F. to about 1200° F. Currently, the preferred oxidizing ambient is air. This activation is carried out for a time period of about 1 minute to about 50 hours. This allows for at least a portion of any chromium in a lower valance state to be converted to a hexavalent state.
The polymerizing is also conducted in the presence of at least one trialkylboron with a formula, BR
3
, where R is an alkyl group of up to 12 carbon atoms. Pre
Benham Elizabeth A.
Bergmeister Joseph J.
McDaniel Max P.
Secora Steven J.
Hon Sow-Fun
Phillips Petroleum Company
Pyon Harold
Williams Morgan & Amerson P.C.
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