Polyurethane-modified bitumen sheet material and method for protective moisture barrier

A modified, urethane bitumen sheet material adapted for use as a moisture barrier for masonry, which sheet material comprises:

• a) a bitumen layer which comprises bitumen, a filler material, a mineral oil tackifier agent and an amount of about 2% to 30% by weight of the bitumen layer of a urethane polymer to impart non-flow properties and surface tackiness to the bitumen layer in use over a temperature range of about 25.degree. F. to 100.degree. F., the urethane polymer prepared by the reaction in the presence of a curing agent of an aromatic diisocyanate with a long-chain polybutadiene hydrocarbon with hydroxyl terminal groups to form a urethane polymer;
• b) a thin, outer, cross-linked, olefinic, polymer film bonded to one surface of the bitumen layer;
• and
• c) a releasable paper on the other surface of the bitumen layer, which releasable paper is subject to removal prior to use of the sheet material to expose a tackified surface of the bitumen layer for application of the tackified surface to the surface of the masonry to be protected.

A urethane-modified bitumen moisture barrier sheet material adapted for use as a moisture barrier against a masonry wall surface, and which sheet material is produced by the method of:

• a) preparing a hot, melted bitumen composition which comprises bitumen and a minor modifying amount of a urethane polymer, which urethane polymer is prepared by the reaction of a polyisocyanate with a long-chain polydiene hydrocarbon having terminal groups which react with the polyisocyanate to form the urethane polymer to provide stable, nonflow properties and surface tackiness properties to the bitumen layer over the range of about 10.degree. F. to 125.degree. F.;
• b) applying a layer of the melted bitumen composition onto a releasable film, which film may be easily removed from the cooled surface of the bitumen layer prior to use;
• c) applying an outer polymeric film to an exposed surface of the bitumen layer to bond the outer polymeric film to the bitumen layer;
• d) cooling the bitumen layer;
• and
• e) recovering the sheet material for use as a moisture barrier sheet material.