Shear thinning ethylene/alpha-olefin interpolymers and their preparation

Abstract

Shear-thinning ethylene/α-olefin and ethylene/α-olefin/diene monomer interpolymers that do not include a traditional branch-inducing monomer such as norbornadiene are prepared at an elevated temperature in an atmosphere that has little or no hydrogen using a constrained geometry complex catalyst and an activating cocatalyst.

1 . A shear thinning ethylene/α-olefin interpolymer, the interpolymer having polymerized therein ethylene, at least one α-olefin monomer and, optionally, at least one diene monomer and being characterized by a Processing Rheology Ratio (PRR) of at least four, where PRR=(interpolymer Viscosity measured at 190° C. with a shear rate of 0.1 rad/sec)/(interpolymer Viscosity measured at 190° C. with a shear rate of 100 rad/sec)+[3.82−interpolymer Mooney Viscosity (ML 1+4  @ 125° C.)]×0.3.  
     
     
         2 . The interpolymer of  claim 1 , wherein the interpolymer has (a) a weight ratio of ethylene to α-olefin within a range of from 90:10 to 10:90, the α-olefin being a C 3-20  α-olefin and (b) a diene monomer content within a range of from 0 to 25 percent by weight, based on interpolymer weight.  
     
     
         3 . The interpolymer of  claim 1 , wherein the interpolymer has a Mooney Viscosity (ML 1+4  at 125° C.) within a range of from 0.5 to about 200.  
     
     
         4 . The interpolymer of  claim 1 , wherein the interpolymer has a molecular weight distribution (Mw/Mn) of at least 2.0.  
     
     
         5 . The interpolymer of  claim 4 , wherein the molecular weight distribution is at least 2.5 and the PRR is at least 8.  
     
     
         6 . The interpolymer of  claim 1 , wherein the interpolymer is an EAODM interpolymer with a molecular weight distribution of at least 2.3, a Mooney Viscosity (ML 1+4  at 125° C.) of at least 15 and a PRR of at least 20.  
     
     
         7 . The interpolymer of  claim 1 , wherein the interpolymer is an ethylene/octene-1 copolymer with a molecular weight distribution of at least 2.3, a Mooney Viscosity (ML 1+4  at 125° C.) of at least 5.  
     
     
         8 . The interpolymer of  claim 2 , wherein the alpha-olefin is selected from the group consisting of propylene, butene-1, pentene-1,4-methyl-pentene-1, hexene-1, octene-1, styrene, p-methyl styrene and mixtures thereof, and the optional diene monomer is selected from the group consisting of 5-ethylidene-2-norbornene, 5-vinylidene-2-norbornene, 5-methylene-2-norbornene, 1,4-hexadiene, 1,3-pentadiene, 7-methyl-1,6-octadiene, 1,3-butadiene, 4-methyl-1,3-pentadiene, 5-methyl-1,4-hexadiene, 6-methyl-1,5-heptadiene and mixtures thereof.  
     
     
         9 . The interpolymer of  claim 2 , further comprising a PRR enhancing amount of an additional diene monomer, the additional diene monomer being selected from the group consisting of dicyclopentadiene, norbornadiene, 1,7-octadiene, and 1,9-decadiene.  
     
     
         10 . A process for preparing ethylene/α-olefin interpolymer of  claim 1 , the process comprising: contacting ethylene, at least one α-olefin monomer and, optionally, at least one diene monomer with a catalyst and an activating cocatalyst under conditions sufficient to attain an ethylene conversion of at least 60 weight percent, the conditions including a temperature of at least 70° C. and, optionally, in the presence of an effective amount of hydrogen, the amount being sufficient to maintain an interpolymer PRR of at least 4, the catalyst being a constrained geometry metal complex  
     
     
         11 . The process of  claim 10 , wherein the amount of hydrogen is greater than 0 mole percent, but less than 0.10 mole percent, based upon total monomer content plus hydrogen content.  
     
     
         12 . The process of  claim 10 , wherein the amount of hydrogen is greater than 0 mole percent, but less than 0.05 mole percent, based upon total monomer content plus hydrogen content.  
     
     
         13 . The process of  claim 10 , wherein the catalyst is selected from the group consisting of (t-butyl-amido)-dimethyl (η 5 -2-methyl-s-indacen-1-yl)silane-titanium (IV) dimethyl, (t-butylamido)-dimethyl-(η 5 -2-methyl-s-indacen-1-yl)silane-titanium (II) 1,3-pentadiene and (t-butylamido)dimethyl-(η 5 -2-methyl-s-indacen-1-yl)silanetitanium (II) 2,4-hexadiene or a Group B catalyst selected from (t-butylamido)-dimethyl(η 5 -2,3-dimethylindenyl)silanetitanium (II) 1,4-diphenyl-1,3-butadiene, (t-butyl-amido)-dimethyl(η 5 -2,3-dimethyl-s-indacen-1-yl)silanetitanium (IV) dimethyl and mixtures thereof.  
     
     
         14 . The process of  claim 10 , wherein the activating cocatalyst is trispentafluorophenyl borane.  
     
     
         15 . The process of  claim 10 , wherein the interpolymer has an ethylene content of from 20 to 95 weight percent (wt %), an α-olefin content of from 80 to 5 wt %, the α-olefin being a C 3-20  α-olefin and, optionally a diene monomer content within a range of from 0 to 25 percent by weight, all percentages based on interpolymer weight and totaling 100 wt %.  
     
     
         16 . The process of  claim 10 , wherein the interpolymer is amorphous.  
     
     
         17 . The process of  claim 10 , wherein the interpolymer is at least partially crystalline and the temperature is at least 80° C. and the ethylene conversion is at least 80%.  
     
     
         18 . An article of manufacture having at least one portion thereof fabricated from a composition that comprises the interpolymer of  claim 1 .  
     
     
         19 . The article of  claim 18 , wherein the article is selected from the group consisting of wire and cable components, electrical insulation, belts, hoses, tubes, gaskets, membranes, molded goods, extruded parts, automotive parts, adhesives, tire walls and tires.  
     
     
         20 . The article of  claim 18 , wherein the composition further comprises at least one additive selected from the group consisting of fillers, fibers, plasticizers, oils, colorants, stabilizers, foaming agents, retarders, accelerators, and cross-linking agents.  
     
     
         21 . An polymer blend composition, the composition comprising more than 50 parts by weight of a crystalline polyolefin resin and less than 50 parts by weight of the interpolymer of  claim 1 , the total amount of crystalline polyolefin resin and interpolymer being 100 parts by weight.  
     
     
         22 . A thermoplastic vulcanizate composition, the composition comprising from 60 to less than 10 parts by weight of a crystalline polyolefin resin and from 40 to more than 90 parts by weight of the interpolymer of  claim 1  wherein the interpolymer is at least partially cross-linked such that the composition has a gel content of at least 70%, based on interpolymer weight, the total amount of crystalline polyolefin resin and interpolymer being 100 parts by weight.  
     
     
         23 . The composition of  claim 21  or  22 , wherein the crystalline polyolefin resin is a polypropylene homopolymer, a copolymer of propylene with an α-olefin selected from the group consisting of ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 2-methyl-1-propene or 4-methyl-1-pentene, or a blend of a polypropylene homopolymer and a propylene/α-olefin copolymer or a mixture thereof.  
     
     
         24 . The composition of  claim 23 , wherein the α-olefin is ethylene.  
     
     
         25 . An article of manufacture fabricated from the composition of any of claims  21 - 24 .