Abstract: The present invention provides a method of making storage-stable road paving binders by blending a minor amount of an unsaturated polymer (e.g., having at least one diene monomer) with a major amount of asphalt at an elevated temperature such that the components are sufficiently fluid to blend; treating the asphalt-polymer blend with a sulfonating agent; and stripping the treated asphalt-polymer blend at an elevated temperature with sufficient stripping gas to remove strippable sulfur moieties and to stabilize the resulting stripped, treated blend. The invention also provides asphaltic compositions made by the method. The asphaltic compositions are useful as binders in road paving applications.

Abstract: The present invention provides for a method of making storage stable road paving binders by blending a minor amount of a polymer having at least one diene monomer with a major amount of asphalt containing at least 0.3% by weight of total nitrogen at an elevated temperature such that the components are sufficiently fluid to blend; treating the asphalt-polymer blend using not more than 250 meq of a sulfonating agent per 100 g of asphalt-polymer blend to introduce the corresponding acid functionality into the blend; maintaining the sulfonated asphalt-polymer blend at a sufficiently elevated temperature and stripping the sulfonated blend with sufficient chemically unreactive gas to remove a major fraction of the acid functionality introduced by sulfonation. The invention also provides for the compositions made by the process. These are useful as binders in road paving applications.