Patent ID: 6075095
Filing Date: 2000-06-13
Classification: C08F

Abstract:
A process for preparing an asymmetrical tin-coupled rubbery polymer having improved stability which comprises: (1) continuously polymerizing in a first reactor at least one diene monomer to a conversion of at least about 90 percent, utilizing an anionic initiator to produce a polymer cement containing living polydiene rubber chains; (2) continuously feeding the polymer cement produced in the first reactor into a second reactor; (3) adding a tin halide to the polymer cement in a second reactor under conditions of agitation to produce a polymer cement having the tin halide homogeneously dispersed therein, wherein the residence time in the second reactor is within the range of about 15 minutes to about 4 hours; (4) continuously feeding the polymer cement having the tin halide homogeneously dispersed therein into a plug flow reactor having a residence time of about 15 minutes to about 1 hour to produce a polymer cement of the asymmetrically tin-coupled rubbery polymer; and (5) continuously withdrawing the polymer cement of the asymmetrically tin-coupled rubbery polymer from the plug flow reactor and adding shortstop to the withdrawn polymer cement.