Patent ID: 7901563

Claim:
A method for preparing an industrial asphalt from a hard asphalt flux comprising (1) heating the hard asphalt flux to a temperature which is within the range of about 400° F. to 550° F. to produce a hot asphalt flux, (2) sparging an oxygen containing gas through the hot asphalt flux for a period of time which is sufficient to increase the softening point of the asphalt flux to a value which is within the range of 100° F. to 175° F., to produce an underblown asphalt composition, and (3) mixing a sufficient amount of a polyphosphoric acid throughout the underblown asphalt composition while the underblown asphalt composition is maintained at a temperature which is within the range of 200° F. to 550° F. to attain a softening point which is within the range of 185° F. to 250° F. and a penetration value of at least 15 dmm to produce the industrial asphalt.