Abstract
Much of the polyurethane foam used in residential and commercial construction is applied as spray-on roof insulation. The current formulating trend in this type of foam is replacing CFC-11 with HCFC-141b. Some formulation adjust ments (catalyst and blowing agent levels, etc.) are required when converting from CFC-11 to HCFC-141b.
A weatherproofing coating must be applied to the sprayed-on roof. These coatings are usually elastomeric acrylics, silicones or urethanes. Selection of the coating nor mally lies with the spray foam contractor. Coverage costs and regional preferences can also play a role in coating selection. Regardless of the coating type, however, the foam/coating package must meet building codes.
In order for a coating/spray foam roofing package to perform properly, the bond between the coating and the foam must be good and permanent. This study com pares the adhesion of various commercially available coatings to HCFC-141b and CFC-11 blown foams, respectively, under different environmental conditions. The foam formulation used in this work was obtained from product literature, and the chemical components in the formulation are commercially available. The foam samples were prepared with commercial spraying equipment. Sample preparation technique provided a flat surface to allow coating applications of consistent wet film thicknesses. Coated samples were allowed to cure and were then subjected to aging under various conditions (heat, cold, humidity). Peel tests after aging were run on a laboratory tensile tester.
Experimental procedures (sample preparation, test methods, etc.) are described, results are reported and general comments are displayed.
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