Thermoplastic olefin elastomers and process for their preparation

Abstract

Disclosed are thermoplastic elastomeric compositions comprising: ps A) from 10 to 80% by weight of one or more crystalline polymer of propylene containing from 0.05 to 15% in moles of ethylene unsaturations, or a mixture of the above polymer with a saturated thermoplastic olefin polymer in quantities lower than or equal to 80% by weight; B) from 20 to 90% by weight of an unsaturated elastomeric olefin polymer; said compositions having been dynamically cross-linked with a cross-linking agent comprising a free radical generator.

1 . A thermoplastic elastomeric composition comprising: 
 A) from 10 to 80% by weight of one or more crystalline polymer of propylene containing from 0.05 to 15% in moles of ethylene unsaturations, or a mixture of the above polymer with a saturated thermoplastic olefin polymer in quantities lower than or equal to 80% by weight;    B) from 20 to 90% by weight unsaturated of an unsaturated elasomeric olefin polymer;    said composition having been dynamically cross-linked with a cross-linking agent comprising a free radical generator.    
     
     
         2 . The thermoplastic elastomeric composition of  claim 1 , wherein the free radical generator is an organic peroxide.  
     
     
         3 . The thermoplastic elastomeric composition of  claim 1 , wherein the unsaturations present in component (A) are obtained by copolymerization with a conjugated diene or nonconjugated C 4 -C 10 .  
     
     
         4 . The thermoplastic elastomeric composition of  claim 1 , wherein component (B) is an ethylene/propylene/2-ethylidene-5-norbornene terpolymer containing from 25 to 70% by weight of propylene and from 4 to 10% by weight of 2-ethylidene-5-norbornene.  
     
     
         5 . A process for the preparation of the thermoplastic elastomeric composition of  claim 1 , comprising a dynamic cross-linking step consisting of subjecting components (A) and (B) to mixing at a temperature higher than or equal to their softening or melting point, in the presence of a cross-linking agent, continuing said mixing during the cross-linking step.