Chemical modification of natural and petroleum residual bitumens to improve protective properties

摘要

A modified bitumen for surface coating compositions comprises the reaction product obtained by heating a bitumen, e.g. a natural bitumen or an oxidized petroleum residual, with an ethylenically unsaturated acid or anhydride, maleic acid and anhydride being the preferred examples. The acid or anhydride should comprise 0.5 to 10% by weight of the bitumen and should be added to the heated, liquid bitumen at about 185 DEG C., heating being continued at about 195 DEG C. until the required thixotropic condition is attained. The reaction product may be reacted with a mono- or polyhydric alcohol, e.g. glycerol, and this product dissolved in white spirit, to which may be added a filler, e.g. asbestine, asbestos, mica, or sand, or an aliphatic amine, e.g. stearylamine or oleylamine, or salt thereof. Polysiloxane in amounts of 0.01 to 0.05% by weight of the total may be added to improve the drying properties. Four specific examples are described.