Dynamic vulcanization of polymer blends from series reactors

A method of dynamically vulcanizing a solution polymerized polymer blend to form a thermoplastic vulcanizate, comprising the steps of

• a) feeding a first set of monomers selected from the group consisting of ethylene and higher alpha-olefin, and a solvent, in a first continuous flow stirred tank reactor,
• b) adding a metallocene catalyst to said first reactor, in an amount of 50-100 weight % of the total amount of catalyst added to all reactors,
• c) operating said first reactor to polymerize the monomers to produce an effluent containing a first polymer,
• d) feeding the effluent of (c) to a second continuous flow stirred tank reactor,
• e) feeding a second set of monomers selected from the group consisting of ethylene, higher alpha-olefin and non-conjugated diene, and optionally additional solvent, to said second reactor,
• f) operating said second reactor to polymerize the monomers to produce a second polymer containing diene,
• g) recovering the resulting first and second polymers and blending them under conditions of heat and shear such that the blend will flow, and
• h) adding a curing agent to the blend under said conditions, to at least partially crosslink the diene-containing polymer and form a dispersion of cured diene-containing particles in a matrix of the first polymer,
• wherein the monomer proportions in the first and second reactors are controlled so that the first polymer contains from 0 to about 85 weight % ethylene, the second polymer contains from more than 0 to about 85 weight % ethylene, and the polymer blend of (g) contains from about 6 to about 85 weight % ethylene.