Process for producing homogeneous polyethylenes

• US 5,492,986 A
• Filed: 03/31/1994
• Issued: 02/20/1996
• Est. Priority Date: 03/31/1994
• Status: Expired due to Fees

• Current Assignee: Union Carbide Chemicals & Plastics Technology Corporation (Dow, Inc.)
• Original Assignee: Union Carbide Chemicals & Plastics Technology Corporation (Dow, Inc.)
• Inventors: Bai, Xinlai
• Primary Examiner(s): TESKIN, FRED M
• Application Number:
  US08/221,247
• Time in Patent Office: 691 Days
• Field of Search: 526/129, 526/144, 526/336, 526/901, 526/904, 526/169.2
• US Class Current: 526/144
• CPC Class Codes: C08F 210/14 Monomers containing five or more carbon atoms
• CPC Class Codes: C08F 210/18 with non-conjugated dienes, e.g. EPT rubbers
• CPC Class Codes: C08F 2500/03 Narrow molecular weight distribution, i.e. Mw/Mn < 3
• CPC Class Codes: C08F 2500/08 Low density, i.e. < 0.91 g/cm3
• CPC Class Codes: C08F 2500/12 Melt flow index or melt flow ratio
• CPC Class Codes: C08F 4/68 Vanadium, niobium, tantalum or compounds thereof
• CPC Class Codes: Y10S 526/901 Monomer polymerized in vapor state in presence of transition metal containing catalyst
• CPC Class Codes: Y10S 526/904 Monomer polymerized in presence of transition metal containing catalyst at least part of which is supported on a polymer, e.g. prepolymerized catalysts

Abstract

A process for the production of a homogeneous polyethylene comprising contacting a mixture comprising ethylene, one or more alpha-olefins, and one or more unconjugated dienes, under polymerization conditions, with a catalyst system comprising:

(a) a catalyst precursor, in independent or prepolymer form, consisting of vanadium (acetylacetonate)₃ ;

(b) optionally, a support for said precursor;

(c) a cocatalyst consisting of a trialkylaluminum; and

(d) a promoter consisting of an unsaturated aliphatic halocarbon having at least 3 carbon atoms and at least 6 halogen atoms or a haloalkyl substituted aromatic hydrocarbon wherein the haloalkyl substituent has at least 3 halogen atoms,

with the proviso that sufficient unconjugated diene is present in the mixture to provide, in the homogeneous polyethylene, about 0.01 to less than about one percent by weight diene based on the weight of the homogeneous polyethylene.

Claims

1. A process for the production of a homogeneous polyethylene comprising contacting a mixture comprising ethylene, one or more alpha-olefins, and one or more unconjugated dienes, under polymerization conditions, with a catalyst system comprising:

(a) a catalyst precursor, in independent or prepolymer form, consisting of vanadium (acetylacetonate)₃ ;

(b) optionally, a support for said precursor;

(c) a cocatalyst consisting of a trialkylaluminum halide; and

(d) a promoter consisting of an unsaturated aliphatic halocarbon having at least 3 carbon atoms and at least 6 halogen atoms or a haloalkyl substituted aromatic hydrocarbon wherein the haloalkyl substituent has at least 3 halogen atoms,

with the proviso that sufficient unconjugated diene is present in the mixture to provide, in the homogeneous polyethylene, about 0.01 to less than about one percent by weight diene based on the weight of the homogeneous polyethylene.

2. The process defined in claim 1 wherein the unconjugated diene is present in the mixture in an amount sufficient to provide, in the homogeneous polyethylene, about 0.1 to about 0.8 percent by weight diene based on the weight of the homogeneous polyethylene.

3. The process defined in claim 1 wherein the unconjugated diene is 1,7-octadiene.

4. The process defined in claim 1 wherein the cocatalyst is triethylaluminum.

5. The process defined in claim 1 wherein the promoter is perchloropropene or trichlorotoluene.

6. The process defined in claim 1 wherein the process is carried out in the gas phase in one or more fluidized beds.

7. A process for the production of a homogeneous polyethylene comprising contacting a mixture comprising ethylene, one or more alpha-olefins having 2 to 12 carbon atoms, and one or more unconjugated dienes having 5 to 12 carbon atoms, in the gas phase in one or more fluidized beds, under polymerization conditions, with a catalyst system comprising:

(A) a catalyst precursor, in independent or prepolymer form, consisting of vanadium (acetylacetonate)₃ ;

(B) optionally, a support for said precursor;

(C) a promoter consisting of perchloropropene; and

(D) a cocatalyst consisting of triethylaluminum

with the proviso that sufficient unconjugated diene is present in the mixture to provide, in the homogeneous polyethylene, about 0.1 to about 0.8 percent by weight diene based on the weight of the homogeneous polyethylene.