NdBR WITH MOLAR MASS BREAKDOWN

Abstract

The invention relates to neodymium-catalysed polybutadienes (NdBR) comprising >95 wt % of cis-1,4 units and <1 wt % of 1,2-vinyl content, based on the neodymium-catalysed polybutadiene, wherein the NdBR evinces a molar mass breakdown of not less than 25%.

1 . A process for the production of neodymium-catalysed polybutadiene (NdBR), the process comprising:
 a) polymerizing butadiene monomer in a first mixture comprising at least one inert organic solvent and at least one catalyst based on neodymium compounds at a reaction temperature of 60° C. to 140° C.,   b) admixing reactive compounds into the first mixture, stopping the polymerization and forming a first polymer, the first polymer having a first Mooney viscosity,   c) admixing sulphur chlorides and the first polymer while maintaining the temperature of the first polymer at essentially the reaction temperature, thereby forming a Mooney jumped polymer having a second Mooney viscosity greater than the first Mooney viscosity, and   d) admixing to the Mooney jumped polymer and a masticating agent.   
     
     
         2 . The process according to  claim 1 , further comprising:
 c1) after step c) and prior to step d), measuring the Mooney viscosity of the Mooney jumped polymer,   e) after step d) again measuring the Mooney viscosity of the polymer, and   f) calculating the molar mass breakdown % of the polymer.   
     
     
         3 . The process according to  claim 2 , wherein admixing the Mooney jumped polymer and masticating agent comprises admixing the Mooney jumped polymer with an amount of masticating agent whereby the molar mass breakdown % is not less than 33. 
     
     
         4 . The process according to  claim 1 , wherein the temperature in step c) is 66° C. to 140° C. 
     
     
         5 . The process according to  claim 1 , further comprising performing step c) for less than 15 minutes. 
     
     
         6 . The process according to  claim 1 , wherein sulphur chloride conversion is >90%. 
     
     
         7 . The process according to  claim 1 , wherein the catalyst based on neodymium compounds comprises:
 component A: an alkoxide, a phosphate or a carboxylase of neodymium,   component B: an alkylaluminium compound,   component C: a diene, and   component D: at least one halogen compound.   
     
     
         8 . The process according to  claim 1 , wherein the reactive compounds comprise stearic acid or lauric acid. 
     
     
         9 . The process according to  claim 1 , wherein the temperature in step c) is 75° C. to 100° C. 
     
     
         10 . The process according to  claim 1 , further comprising adding a stabilizer after the admixture of sulphur chlorides. 
     
     
         11 . The process according to  claim 1 , wherein admixing of the sulphur chlorides comprises admixing 0.05 to 0.7 part by weight of the sulphur chlorides per 100 parts by weight of the first polymer. 
     
     
         12 . The process according to  claim 1 , wherein the sulphur chlorides comprise disulphur dichloride, sulphur dichloride, thionyl chloride or any mixture thereof. 
     
     
         13 . Rubber mixtures containing neodymium-catalysed polybutadiene (NdBR) formed according to the process of  claim 1 , wherein the neodymium-catalysed polybutadiene comprises >90 wt % of cis-1,4 units and <1 wt % of 1,2-vinyl butadiene content, based on the neodymium-catalysed polybutadiene, and wherein the neodymium-catalysed polybutadiene evinces a molar mass breakdown % of not less than 25%. 
     
     
         14 . The rubber mixtures according to  claim 13 , wherein the neodymium-catalysed polybutadiene evinces a molar mass breakdown % of not less than 33%. 
     
     
         15 . The rubber mixtures according to  claim 13 . 
     
     
         16 . The process according to  claim 1 , further comprising repeating steps d), e) and f). 
     
     
         17 . The process according to  claim 2 , wherein:
 admixing the Mooney jumper polymer and masticating agent comprises admixing the Mooney jumped polymer with an amount of masticating agent whereby the molar mass breakdown % is not less than 50%; and   calculating the molar mass breakdown % of the polymer comprises computing the molar mass breakdown % via the equation:
   molar mass breakdown %=( K−L )/ K* 100 
 where;
 K=Mooney viscosity (ML 1+4 at 100° C.) of polymer before mixing with masticating agent, and 
 L=Mooney viscosity (ML 1+4 at 100° C.) of the same polymer after mixing with masticating agent. 
 
   
     
     
         18 . The process according to  claim 17 , wherein:
 the temperature in step c) is 66° C. to 140° C., and the process comprises performing step c) for less than 10 minutes; and   the amount of masticating agent is 0.1 wt % to 2 wt % based on the polymer.   
     
     
         19 . The process according to  claim 18 , wherein:
 the temperature in step c) is 75° C. to 100° C., and sulphur chloride conversion is >97%; and   the masticating agent comprises a mixture containing iron phthalocyanine and 2,2′-dibenzamidodiphenyl disulphide, waxes and fillers.   
     
     
         20 . The process according to  claim 19 , wherein:
 admixing of the sulphur chlorides comprises admixing 0.1 to 0.4 parts by weight of the sulphur chlorides, per 100 parts by weight of the first polymer;   the catalyst comprises:   component A; neodymium versatate,
 component B: diisobutylaluminium hydride (DIBAH), 
 component C: butadiene, and 
 component D: ethylaluminium sesquichloride (EASC); 
   the reactive compounds comprise stearic acid or lauric acid;   the sulphur chlorides comprise disulphur dichloride, sulphur dichloride, thionyl chloride or any mixture thereof; and   the process further comprises adding a stabilizer after the admixture of sulphur chlorides.