Ethylene interpolymer polymerizations

Abstract

A new process of interpolymerizing ethylene interpolymer products having improved properties, such as increased onset of crystallization temperature, is disclosed. Preferably, the process comprises interpolymerizing a first homogeneous ethylene/alpha-olefin interpolymer and at least one second homogeneous ethylene/alpha-olefin interpolymer using-at least two constrained geometry catalysts having different reactivities such that the first ethylene/alpha-olefin interpolymer has a narrow molecular weight distribution (NMWD) with a very high comonomer content and relatively high molecular weight and the second ethylene/alpha-olefin interpolymer has a NMWD with a low comonomer content and a molecular weight lower than that of the first interpolymer. The resultant first homogeneous interpolymer is combined with the resultant second homogeneous interpolymer in appropriate weight ratios resulting in the desired finished polymer structure. The first interpolymer and the second interpolymer can be polymerized in a single reactor or they can be polymerized in separate reactors operated in parallel or series.

What is claimed is:  
     
         1 . A process for preparing an ethylene polymer product, comprising the steps of: 
 (a) polymerizing a first homogeneous ethylene polymer using a first activated constrained geometry catalyst composition having a first reactivity such that the first polymer has a melt index of from about 0.05 to about 50 grams/10 minutes,    (b) polymerizing at least one second homogeneous ethylene polymer using a second activated constrained geometry catalyst composition having a second reactivity such that the second ethylene polymer has a melt index of from about 0.05 to about 50 grams/10 minutes, and    (c) combining from about 50 to about 95 weight percent of the first ethylene polymer with from about 5 to about 50 weight percent of the second ethylene polymer to form an ethylene polymer product.    
     
     
         2 . A process for preparing an ethylene/alpha-olefin interpolymer product, comprising the steps of: 
 (a) polymerizing a first homogeneous ethylene/alpha-olefin interpolymer using a first activated constrained geometry catalyst composition having a first reactivity such that the first interpolymer has from about 5 to about 30 weight percent comonomer content, a melt index of from about 0.05 to about 50 grams/10 minutes, a melting point less than about 110° C.,    (b) polymerizing at least one second homogeneous ethylene/alpha-olefin interpolymer using a second activated constrained geometry catalyst composition having a second reactivity such that the second ethylene/alpha-olefin interpolymer has from about 2 to about 10 weight percent comonomer content, a melt index of from about 0.05 to about 50 grams/10 minutes, a melting point greater than about 115° C., and    (c) combining from about 50 to about 95 weight percent of the first homogeneous ethylene/alpha-olefin interpolymer with from about 5 to about 50 weight percent of the second homogeneous ethylene/alpha-olefin interpolymer to form an ethylene/alpha-olefin interpolymer product.    
     
     
         3 . The process of claims  1  or  2  wherein the first activated constrained geometry catalyst composition comprises a titanium constrained geometry complex and an aluminoxane cocatalyst.  
     
     
         4 . The process of claims  1  or  2  wherein the second activated constrained geometry catalyst composition comprises a zirconium constrained geometry complex and an aluminoxane cocatalyst.  
     
     
         5 . The process of claims  1  or  2  wherein the second activated constrained geometry catalyst composition comprises a zirconocene constrained geometry complex and an aluminoxane cocatalyst.  
     
     
         6 . The process of  claim 2  wherein (a) and (b) are performed substantially simultaneously in a common reactor.  
     
     
         7 . The process of  claim 6  further comprising the steps of: 
 (d) mixing the first and second catalyst compositions together to form a catalyst mixture, and  
 (e) injecting the catalyst mixture into the common reactor.  
 
     
     
         8 . The process of  claim 2  wherein (a) and (b) are performed separately in at least two reactors.  
     
     
         9 . The process of  claim 8  wherein the two reactors comprise at least a first reactor and a second reactor and wherein the two reactors are operated in series.  
     
     
         10 . The process of  claim 8  wherein the two reactors are operated in parallel.  
     
     
         11 . The process of  claim 2  wherein the homogeneous ethylene/alpha-olefin interpolymer produced in step (a) has a melting point from about 70° C. to about 110° C. and wherein the homogeneous ethylene/alpha-olefin interpolymer produced in step (b) has a melting point from about 115° C. to about 130° C.  
     
     
         12 . The process of  claim 2  wherein at least one of the alpha-olefins is a C 2 -C 18  alpha-olefin.  
     
     
         13 . The process of  claim 12  wherein at least one of the alpha-olefins is selected from the group consisting of ethylene, 1-propene, isobutylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.  
     
     
         14 . The process of  claim 13  wherein the first and the second ethylene/alpha-olefin interpolymer each comprises a copolymer of ethylene and 1-octene.  
     
     
         15 . The process of  claim 2  wherein either the first or the second activated constrained geometry catalyst compositions, or both, are chosen from constrained geometry catalyst components selected from the group consisting of titanium, vanadium, hafnium and zirconium.  
     
     
         16 . The interpolymer product of  claim 2  wherein the first homogeneous ethylene/alpha-olefin interpolymer and the second homogeneous ethylene/alpha-olefin interpolymer are combined in amounts effective to yield an interpolymer product having a crystallization onset temperature at least about 5° C. higher than the crystallization onset temperature of the interpolymer produced by the activated constrained geometry catalyst composition having the higher reactivity.  
     
     
         17 . The interpolymer product of  claim 2  wherein the first homogeneous ethylene/alpha-olefin inter-polymer and the second homogeneous ethylene/alpha-olefin interpolymer are combined in amounts effective to yield a crystallization onset temperature of at least about 110° C.  
     
     
         18 . The interpolymer product of  claim 2  wherein the first and the second ethylene/alpha-olefin interpolymer each comprises a copolymer of ethylene and 1-octene.  
     
     
         19 . A fabricated article made from the interpolymer product of  claim 16 .  
     
     
         20 . The fabricated article of  claim 19  selected from the group consisting of films, molded articles, and fibers.  
     
     
         21 . A process for preparing an ethylene/alpha-olefin terpolymer product, comprising the steps of: 
 (a) interpolymerizing ethylene, a first comonomer and a second comonomer to form a terpolymer using a first activated constrained geometry catalyst composition having a first reactivity and a second activated constrained geometry catalyst composition having a second reactivity to form an ethylene/alpha-olefin terpolymer product, and    (b) recovering the ethylene/alpha-olefin terpolymer product.    
     
     
         22 . The process of  claim 21  wherein the first comonomer is 1-propene and the second comonomer is 1-octene.  
     
     
         23 . The process of  claim 22  wherein wherein the first activated constrained geometry catalyst composition comprises a titanium constrained geometry complex and an aluminoxane cocatalyst and wherein the second activated constrained geometry catalyst composition comprises a zirconium constrained geometry complex and an aluminoxane cocatalyst.  
     
     
         24 . The process of  claim 21  wherein the ethylene, the first comonomer and the second comonomer are interpolymerized in a common reactor.