Methods of production of ethylene copolymers having narrow composition distributions and high melting temperatures

Abstract

A copolymer of ethylene and at least one comonomer containing at least 4 carbon atoms is characterized by a polydispersity greater than 2, a broad melting point transition as measured by differential scanning calorimetry, and a narrow composition distribution. Ethylene/C 4+ copolymers also may show at least one peak melting point above the peak melting point of a random copolymer of the same monomer unit composition. These copolymers are made by contacting ethylene and a comonomer under polymerization conditions in the presence of a suitable fluxional catalyst system.

1 . A copolymer of ethylene with at least one comonomer containing at least 4 carbon atoms characterized by a polydispersity greater than 2, a broad melting point transition as measured by differential scanning calorimetry, and a narrow composition distribution.  
     
     
         2 . A copolymer of  claim 1  wherein the comonomer is at least one olefin containing from 4 to about 12 carbon atoms.  
     
     
         3 . A copolymer of  claim 1  wherein the comonomer is an alpha-olefin containing 4 to about 8 carbon atoms.  
     
     
         4 . A copolymer of  claim 1  wherein the comonomer is 1-butene, 1-pentene, 1-hexene, 1-octene, or 4-methyl-1-pentene, or mixtures thereof.  
     
     
         5 . A copolymer of  claim 1  wherein the comonomer is 1-hexene.  
     
     
         6 . A copolymer of  claim 1  wherein the melting point transition is greater than about 50° C.  
     
     
         7 . A copolymer of  claim 1  wherein the melting point transition is greater than about 100° C.  
     
     
         8 . A copolymer of  claim 1  wherein the polydispersity is greater than about 3.  
     
     
         9 . A copolymer of  claim 1  wherein the polydispersity is between about 4 and about 12.  
     
     
         10 . A copolymer of  claim 1  wherein the solvent-fractionated composition distribution is less than or equal to 15%.  
     
     
         11 . A copolymer of  claim 1  wherein the solvent-fractionated composition distribution is less than or equal to 12% and the comonomer is 1-butene, 1-pentene, 1-hexene, 1-octene, or 4-methyl-1-pentene, or mixtures thereof.  
     
     
         12 . A copolymer of  claim 1  wherein the solvent-fractionated composition distribution is less than or equal to 10%.  
     
     
         13 . A copolymer of  claim 1  wherein the comonomer is 1-butene, 1-hexene, or 1-octene, the composition distribution is less than 12%, the melting point transition is greater than 75° C., and the polydispersity is greater than 3.  
     
     
         14 . A copolymer of  claim 1  which is elastomeric.  
     
     
         15 . A copolymer of  claim 1  which is plastomeric.  
     
     
         16 . A copolymer of  claim 1  in which the molecular weight-fractionated composition distribution of is less than about 5%.  
     
     
         17 . A copolymer of  claim 1  which contains about 1 to about 50 mole percent of comonomer.  
     
     
         18 . A copolymer of  claim 17  which contains up to about 40 mole percent of comonomer.  
     
     
         19 . A copolymer of  claim 1  which contains up to about 10 mole percent comonomer.  
     
     
         20 . A copolymer of  claim 19  which contains from 1 to about 5 mole percent comonomer.  
     
     
         21 . The copolymer of  claim 1 , wherein the copolymer is formed as a pellet.  
     
     
         22 . The copolymer of  claim 21 , wherein said pellet contains polymer stabilizers.  
     
     
         23 . The copolymer of  claim 1 , wherein the copolymer is formed as a molded or extruded article.  
     
     
         24 . The copolymer of  claim 23 , wherein said article is a pipe or a container.  
     
     
         25 . The copolymer of  claim 1 , wherein the copolymer is formed as a film.  
     
     
         26 . The copolymer of  claim 25 , wherein said film has a thickness from about 0.1 to about 100 mil.  
     
     
         27 . A film of  claim 26  with a thickness from 0.5 to 20 mil.  
     
     
         28 . A copolymer of ethylene with at least one comonomer containing at least 4 carbon atoms characterized by at least one peak melting point above the peak melting point of a random copolymer of the same monomer unit composition.  
     
     
         29 . A copolymer of  claim 28  in which at least one comonomer contains 6 carbon atoms.  
     
     
         30 . A copolymer of  claim 28  which is an elastomer.  
     
     
         31 . A copolymer of  claim 28  which is a plastomer.  
     
     
         32 . A copolymer of  claim 31 , wherein the copolymer is formed as a film.  
     
     
         33 . A copolymer of  claim 28  in which the solvent-fractionated composition distribution is less than about 15%.  
     
     
         34 . A copolymer of  claim 33  in which at least one comonomer is an alpha olefin which contains 4 to about 10 carbon atoms.  
     
     
         35 . A copolymer of  claim 34  A copolymer of  claim 1  which contains from about 1 to about 40 mole percent of comonomer.  
     
     
         36 . A copolymer of  claim 35  which has a solvent-fractionated composition distribution less than about 12%.  
     
     
         37 . A copolymer of  claim 36  which has a polydispersity of above 2 to about 12.  
     
     
         38 . A copolymer of  claim 37  which contains up to 10 mole percent comonomer.  
     
     
         39 . A copolymer of  claim 38  which is plastomeric and which contains from 1 to about 5 mole percent comonomer.  
     
     
         40 . A method to make a copolymer of  claim 1  wherein ethylene and a comonomer are contacted under polymerization conditions in the presence of a fluxional catalyst system.  
     
     
         41 . The method of  claim 40  in which the metallocene component of the fluxional catalyst system has more than two symmetry states.  
     
     
         42 . The method of  claim 40  in which the fluxional catalyst system contains a substituted 2-arylindenyl metallocene component.  
     
     
         43 . The method of  claim 40  wherein hydrogen is a component of the catalyst system in an amount sufficient form a plastomeric copolymer product.  
     
     
         44 . The method of  claim 40  in which the metallocene component of the fluxional catalyst system contains zirconium or hafnium.  
     
     
         45 . The method of  claim 44  in which the metallocene component of the fluxional catalyst system contains hafnium.  
     
     
         46 . The method of  claim 40  wherein wherein the fluxional catalyst system contains a metallocene component with at least on ligand with the structure:  
       
         
           
           
               
               
           
         
       
       where R 4 -R 14  may be the same or different substituents comprising hydrogen, halogen, or aryl, hydrocarbyl, silahydrocarbyl, or halohydrocarbyl moities containing up to 12 carbon atoms.  
     
     
         47 . The method of  claim 46  wherein R5 and R7 are bulky sustituents.  
     
     
         48 . The method of  claim 47  wherein wherein R5 and R7 are t-butyl, trifluoromethyl, or trimethylsilyl, or combinations thereof.  
     
     
         49 . A method to make a copolymer of  claim 28  wherein wherein ethylene and a comonomer are contacted under polymerization conditions in the presence of a fluxional catalyst system.