Patent ID: 6429241
Filing Date: 2002-08-06
Classification: C08L

Abstract:
A method of forming a bituminous composition consisting essentially of bitumen, elastomeric polymer and sulfur, said method consisting essentially ofdispersing by blending and reacting an elastomeric polymer having a conjugated diene structure and a weight average molecular weight of about 45,000 to about 750,000 with bitumen and a cross-linking agent at a temperature of about 150Â° C. to about 220Â° C. to stably incorporate the elastomeric polymer into the bitumen against phase separation according to ASTM D5892, wherein at least one of the elastomeric polymer and cross-linking agent is added incrementally to the bitumen and reacted to permit greater amounts of elastomeric polymer and/or cross-linking agent to the incorporated into the bitumen than otherwise is possible, and wherein: (a) the total overall quantity of elastomeric polymer to be incorporated into the composition is initially added to and fully dispersed in the bitumen in an amount of about 1 to about 8 wt % of the total composition, and (b) sulfur, as the cross-linking agent, is added incrementally to a total amount of about 3 to about 15 wt % of elastomeric polymer with the sulfur being added in about 2 to about 10 increments over a total period of about 1 to about 12 hours with about 0.5 to about 2 hours between each incremental loading.