Patent ID: 7928164

Claim:
A process for producing a homogeneous polymer blend having one glass transition temperature indicated on a dynamic mechanical thermal analyzer trace of tan δ versus temperature comprising (a) a thermoplastic first polymer having at least 30% crystallinity and a melting temperature at or above 100° C., wherein said thermoplastic first polymer is a polymer of propylene and from 0 to about 5% of an alpha-olefin, by weight of the polymer; (b) a second polymer different from the first polymer and having a crystallinity less than that of the first polymer, and (c) at least one diene having at least two polymerizable unsaturated groups, said second polymer is a polymer of propylene, 2 to 15 weight % of one or more C 2 and/or C 4 to C 10 alpha-olefin comonomers and 0.01 to 5 wt % diene, the process comprising: (i) polymerizing at least one first monomer of propylene to produce the thermoplastic first polymer; and (ii) contacting at least part of said first polymer with at least one second monomer and said diene under conditions sufficient to polymerize said second monomer to produce said second polymer and simultaneously cross-link said second polymer and said at least two polymerizable unsaturated groups such that the product of said contacting (ii) comprises at least a fraction which is insoluble in xylene, wherein the amount of the xylene insoluble fraction is at least 4 wt % of the total weight of the first and second polymers.