| 摘要 |
<p>The present invention relates to specific bitumens that may be used in mixture with block copolymers of the SBS type and oils for the preparation of sealing membranes, characterized in that they are hard bitumens of Newtonian character derived from the treatment of residues in vacuo by propane deasphalting, they have a viscosity of from 560 to 850 s Saybolt furol at 135°C, they present a ''ball and ring'' softening point of between 65 and 74°C, they have a needle penetration at 25°C of 10 to 20/10th of millimetre, and present an asphaltene content of 20 to 35 % by weight. The invention also relates to mixtures that may be used for preparing sealing membranes, and to the membranes thus obtained.</p> |
