Synthetic rubber with narrow molecular weight distribution, a process for its preparation and a method of use
View Patent ↗A novel process is used to prepare synthetic rubbers (B) which feature very narrow molecular weight distribution and a correspondingly low value for the polydispersity index. The preparation process encompasses the treatment of a synthetic rubber with ultrasound, where the resultant synthetic rubber (B) has a lower weight-average molecular weight (M w ) than the synthetic rubber (A) used. The resultant synthetic rubbers (B) have excellent suitability for processing via extruder processes or injection-molding processes.
1. A synthetic rubber selected from the group consisting of nitrile rubbers (NBR), hydrogenated nitrile rubbers (HNBR), ethylene-vinyl acetate copolymers (EVM), EPDM rubbers, emulsion styrene-butadiene rubber (ESBR), chloroprene rubbers (CR), polybutadiene rubbers (BR), acrylate rubbers (ACM), fluororubbers (FKM), IIR and halo IIR, preferably BIIR and CIIR, wherein the synthetic rubber has a polydispersity index (D) of less than 1.9 as calculated via formula (I)
D=M w /M n (I),
where
M w is weight-average molecular weight, and
M n is the number-average molecular weight.
2. The synthetic rubber according to claim 1 wherein the polydispersity index is less than 1.7.
3. The synthetic rubber according to claim 1 , with a polydispersity index of between 1 and 1.9.
4. The synthetic rubber according to claim 1 , wherein the weight-average molecular weight, M w , is from 30,000 to 250,000.
5. The synthetic rubber according to claim 1 having a Mooney viscosity (ML 1+4 @ 100° C.) of from 1 to 50.
6. The synthetic rubber according to claim 1 , having a Mooney viscosity (ML 1+4 @ 100° C.) of from 10 to 40.
7. A method of producing a molding, comprising:
extruding the synthetic rubber according to claim 1 and forming the same into said molding.
8. A method a producing molding, comprising:
injection-molding the synthetic rubber according to claim 1 and forming the same into said molding.
9. A molding comprising the synthetic rubber according to claim 1 .
10. A method of producing tires comprising:
forming the synthetic rubber according to claim 1 into a tire.
11. A tire comprising the synthetic rubber according to claim 1 .
12. The method according to either claim 7 or 8 , wherein the molding is selected from the group of gaskets, hoses, damping elements, stators and cable sheathing.