HYDROGENATED NITRILE RUBBER WITH NARROW MOLECULAR WEIGHT DISTRIBUTION, A PROCESS FOR ITS PREPARATION AND A METHOD OF USE
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 .