Process for producing blends of syndiotactic, 1,2-polybutadiene and rubbery elastomers

Abstract

Blends of syndiotactic 1,2-polybutadiene and rubbery elastomers are prepared by a process that comprises polymerizing 1,3-butadiene monomer into syndiotactic 1,2-polybutadiene within a rubber cement of an elastomeric terpolymer by using a chromium-based, molybdenum-based, or iron-based catalyst composition. Polymer composition comprising the blend with improved properties is also provided.

What is claimed is:  
     
         1 . A process for preparing blends of syndiotactic 1,2-polybutadiene and rubbery elastomers comprising the steps of: 
 (1) providing a mixture of a rubber cement and 1,3-butadiene monomer, where the rubber cement comprises an elastomeric terpolymer polymerized from ethylene, at least one α-olefin monomer, and at least one diene monomer; and    (2) polymerizing the 1,3-butadiene into syndiotactic 1,2-polybutadiene within the rubber cement by using a catalyst composition that is formed by combining (a) a chromium-containing compound, (b) a hydrogen phosphite, and (c) an organomagnesium compound or (a) a molbydenum-containing compound or an iron-containing compound, (b) a hydrogen phosphite, and (c) an organoaluminum compound.    
     
     
         2 . A process for preparing blends of syndiotactic 1,2-polybutadiene and rubbery elastomers comprising the steps of: 
 (1) providing a mixture of rubber cement and 1,3-butadiene monomer, where the rubber cement comprises an elastomeric terpolymer polymerized from ethylene, at least one α-olefin monomer, and at least one diene monomer; and    (2) preparing a catalyst composition, where the catalyst composition is prepared by combining, outside the presence of the mixture of rubber cement and monomer, (a) a chromium-containing compound, (b) a hydrogen phosphite, and (c) an organomagnesium compound or (a) a molybdenum-containing compound or an iron-containing compound or (b) a hydrogen phosphite, and (c) an organomagnesium compound; and    (3) adding the catalyst composition to the mixture and thereby polymerizing the 1,3-butadiene monomer into syndiotactic 1,2-polybutadiene within the rubber cement.    
     
     
         3 . A tire sidewall formulation comprising: 
 a blend of syndiotactic 1,2-polybutadiene and rubbery elastomer comprising: 
 an elastomeric terpolymer polymerized from ethylene, propylene, and at least one diene monomer; and  
 syndiotactic 1,2-polybutadiene having a melting temperature of from about 70° C. to about 210° C.  
   
     
     
         4 . The process of  claim 1 , where the α-olefin monomer is propylene, 1-butene, 1-hexene, 4-methyl-1 pentene, 1-octene, 1-decene, or a combination thereof.  
     
     
         5 . The process of  claim 1 , where the diene monomer is 5-ethylidene-2-norbornene, 1,4-hexadiene, 5-methylene-2-norbornene, 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-methyl-1,6-octadiene, 1,3-cyclopentadiene, 1,4-cyclohexadiene, dicyclopentadiene, 5-vinyl-2-norbornene, or a combination thereof.  
     
     
         6 . The process of  claim 1 , where said step of combining (a) a chromium-containing compound, (b) a hydrogen phosphite, and (c) an organomagnesium compound or said step of combining (a) a molybdenum-containing compound, or an iron-containing compound, (b) a hydrogen phosphite, and (c) an organoaluminum compound, occurs in the presence of at least one type of conjugated diene monomer.  
     
     
         7 . The process of  claim 1 , where said step of polymerizing includes adding from about 0.01 to about 2 mmol of the chromium-containing compound, molybdenum-containing compound, or iron-containing compound per 100 g of 1,3-butadiene.  
     
     
         8 . The process of  claim 1 , where the syndiotactic 1,2-polybutadiene has a melting temperature of from about 70° C. to about 210° C.  
     
     
         9 . The process of  claim 1 , where the blends of syndiotactic 1,2-polybutadiene in rubbery elastomer comprise from about 3 percent to about 12 percent by weight of syndiotactic 1,2-polybutadiene.  
     
     
         10 . The formulation of  claim 3 , where the syndiotactic 1,2-polybutadiene is present in an amount of from about 3 to about 12 percent by weight.  
     
     
         11 . A polymer composition comprising a blend of syndiotactic 1,2-polybutadiene and a terpolymer polymerized from ethylene, at least one α-olefin monomer, and at least one diene monomer.  
     
     
         12 . The polymer composition of  claim 11 , in which the α-olefin monomer is propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, or a combination thereof.  
     
     
         13 . The polymer composition of  claim 11 , in which the α-olefin monomer comprises propylene.  
     
     
         14 . The polymer composition of  claim 11 , in which the diene monomer comprises 5-ethylidene-2-norbornene, 1,4-hexadiene, 5-methylene-2-norbornene, 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, 1,3-cyclopentadiene, 1,4-cyclohexadiene, dicydopentadiene, 5-vinyl-2-norbornene, or a combination thereof.  
     
     
         15 . The polymer composition of  claim 11 , in which the diene monomer comprises 5-ethylidene-2-norbornene.  
     
     
         16 . The polymer composition of  claim 11 , further comprising cis-polybutadiene.  
     
     
         17 . The polymer composition of  claim 11 , furthercomprising natural rubber.  
     
     
         18 . A method to improve the cut growth rate of a polymer product, comprising combining a syndiotactic 1,2-polybutadiene and a terpolymer polymerized from ethylene, at least one α-olefin monomer, and at least one diene monomer, in the formation of the polymer product.  
     
     
         19 . The method of  claim 18  wherein the α-olefin monomer comprises propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, or a combination thereof.  
     
     
         20 . The method of  claim 18  wherein the αa-olefin monomer comprises propylene.  
     
     
         21 . The method of  claim 18  wherein the diene monomercomprises 5-ethylidene-2-norbornene, 1,4-hexadiene, 5-methylene-2-norbornene, 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, 1,3-cyclopentadiene, 1,4-cyclohexadiene, dicyclopentadiene, 5-vinyl-2-norbornene, or a combination thereof.  
     
     
         22 . The method of  claim 18 , further comprising the addition of cis-polybutadiene in the formulation of the polymer product.  
     
     
         23 . The method of  claim 18  wherein the cut growth rate comprises ≧45.