Hydrogenated nitrile rubber with narrow molecular weight distribution, a process for its preparation and a method of use

Abstract

A novel process produces a novel hydrogenated nitrile rubber (B) which features a very narrow molecular weight distribution and a correspondingly low value for the polydispersity index. The preparation process encompasses the treatment of a hydrogenated nitrile rubber (A) with ultrasound, whereupon the resultant hydrogenated nitrile rubber (B) has a lower weight-average molecular weight (M w ) than the hydrogenated nitrile rubber (A). The resultant hydrogenated nitrile rubber (B) has excellent suitability for the production of moldings via processing by extrusion processes or by injection-moulding processes.

1 . The hydrogenated nitrile rubber with a polydispersity D=M w /M n  which is less than or equal to 2. 
     
     
         2 . The hydrogenated nitrile rubber according to  claim 1  with a polydispersity D=M w /M n  which is less than 2. 
     
     
         3 . The hydrogenated nitrile rubber according to  claim 1  with a polydispersity D=M w /M n  which is less than 1.9. 
     
     
         4 . The hydrogenated nitrile rubber according to  claim 1  with a polydispersity D=M w /M n  which is less than 1.7. 
     
     
         5 . The hydrogenated nitrile rubber according to  claim 1 , wherein the polydispersity D=M w /M n  is greater than 1 and smaller than 2. 
     
     
         6 . The hydrogenated nitrile rubber according to  claim 1 , wherein the hydrogenated nitrile rubber is a hydrogenated co- or terpolymer which contains repeat units of at least one conjugated diene, of at least one α,β-unsaturated nitrile and, if appropriate, of one or more copolymerizable monomers. 
     
     
         7 . The hydrogenated nitrile rubber according to  claim 1 , which has a weight-average molecular weight M w  in the range from 30,000 to 250,000. 
     
     
         8 . The hydrogenated nitrile rubber according to  claim 1 , whose Mooney viscosity (ML 1+4@100° C.) is in the range from 1 to 50. 
     
     
         9 . The hydrogenated nitrile rubber according to  claim 1 , whose Mooney viscosity (ML 1+4@100° C.) is in the range from 10 to 40. 
     
     
         10 . A method for producing moldings comprising subjecting the hydrogenated nitrile rubber according to  claim 1  to an extrusion process or to an injection-moulding process. 
     
     
         11 . The method according to  claim 10  for producing gaskets, hoses, damping elements, stators or cable sheathing. 
     
     
         12 . Moldings comprising a hydrogenated nitrile rubber according to  claim 1 .