WEATHER-RESISTIVE BARRIERS FROM SELF COLLAPSING POLYURETHANE FOAMS

摘要

The present invention provides a self-collapsing, moisture curable one component polyurethane foam (1K PU) composition from moisture curable polyurethane prepolymers and to methods of making weather resistant barriers and formed in place gaskets therefrom. The foam compositions are packed under pressure with a blowing agent. In the methods, the foams are applied to gaps in the exterior (sheathing) of a building under construction and collapse on cure to enable application an aqueous weather barrier coating thereover within an hour. The foams also cure when applied on or adjacent a structure to form a foam gasket that enables installation of additional structural elements over or adjacent the foam gasket without bowing or damage to the structure treated.

主权项

1. A method for making a flexible, weather-resistive barrier for use in building and construction comprising applying a self-collapsing, one component polyurethane foam composition (1K PU foam) to a substrate chosen from a gap formed between adjacent sheets of wood, cement or gypsum exterior sheathing on a structural frame of a building under construction, including the margin of the sheathing adjacent the gap to hold the foam composition, and applying an aqueous polymeric coating having a density when dried of greater than 0.7 g/ml over the sheathing,
wherein the one component polyurethane foam contains a) one or more blowing agents and b) one or more isocyanate prepolymers from the reaction of one or more polyisocyanate and one or more polyol in the presence of a catalyst, preferably, a wherein the isocyanate prepolymers have free isocyanate groups in the amount of from 2 to 10 wt. %, based on total isocyanate prepolymer weight.