Composite roof structures prepared using one-part moisture curing polyurethane foaming adhesive compositions containing a reversibly blocked catalyst

Abstract

The present invention relates to composite roof structures and their preparation. The composite roof structure is prepared by applying a one-part, moisture curable, foaming, polyurethane adhesive composition to the roof deck, placing the roofing material in contact with the adhesive composition, and allowing the adhesive mixture to foam, fill, and cure. If multiple layer of the roofing material are used to form the composite roof structure, then the above procedure may be used to adhere each of the roofing material layers.

Description

CROSS REFERENCE TO RELATED[0001]APPLICATIONS (NOT APPLICABLE)STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH (NOT APPLICABLE)BACKGROUND OF THE INVENTION[0002]The invention relates to composite roof structures and their preparation. The composite roof structures are prepared by adhering roofing material to a roof deck using a one-part, moisture curable, polyurethane adhesive composition containing dissolved or dispersed therein, reversibly blocked catalysts that are activated by moisture. Once activated by moisture the polyurethane adhesive composition foams in place. The adhesive compositions are storage stable in the absence of moisture and useful as a gap filling adhesive for adhering the roofing material to irregular surfaces.[0003]In the roofing art many different methods are used to secure roofing materials to the roof deck structure, especially flat roofs. Mechanical fasteners have been used to secure roofing materials such as insulation boards and waterproofing membrane to t...

AI Technical Summary

Benefits of technology

[0007]The composite roof structure is prepared by applying the adhesive to the roof deck and setting roofing material in place on the roof deck. If multiple layers of roofing materials are used or in the case of edge overlap the polyurethane adhesive compositions can be used to adhere the multiple layers or edge overlap. In especially hostile environments such as extreme cold or very low humidity the roof deck may be sprayed with an aqueous solution prior to applying the adhesive composition. When exposed to moisture the adhesive composition foams and cures rapidly providing a gap filling foam and excellent bonds between layers of roofing material and the roof material and roof deck.

Problems solved by technology

However, the use of fasteners is undesirable because the method necessitates puncturing the roofing material and the roof deck.

Even where the fasteners are coated with special materials to prevent corrosion and leakage, separation due to movement caused by thermal expansion and contraction, or wind uplift occurs thus compromising the effectiveness of the seal around the fastener.

The numerous holes created by removing old fasteners weakens the integrity of the roof deck and creates routes of entry for water.

The disadvantages of two-part urethane foams as roofing adhesives are obvious.

Disadvantages of conventional one-part, moisture curing, foamable, urethane adhesive formulations include their limited shelf life.

One shelf life limiting factor is the dimerization of terminal isocyanate groups of the polyurethane prepolymer which is accelerated by catalysts contained in the formulation.

This dimerization of the terminal isocyanate groups, even in tightly sealed containers free of oxygen and / or moisture, leads to discoloration of the prepolymer accompanied by increased viscosity.

Further disadvantages associated with using conventional urethane foams whether one-part or two-part include environmental concerns over blowing agents, disposal of pressurized containers, and lack of fill capabilities of pre-foamed urethanes on irregular substrates.