Method and apparatus for nucleation of polyurethane foam which results in self-adhering microcellular foam

A method of producing a polyurethane foam comprising reacting polyurethane precursors including a polyol and an isocyanate in a static mixer, the method including conducting the polyol precursor from a reservoir to a shearing mixer, introducing a nucleating gas to the polyol in the shearing mixer and intimately mixing the nucleating gas into the polyol in the shearing mixer, the nucleating gas being finely divided and uniformly distributed in the polyol, and conducting the polyol and nucleating gas to a parallel valving system;

• conducting the isocyanate precursor to the parallel valving system and introducing the polyol and isocyanate through the parallel valving system to a mixer, and reacting the polyol and isocyanate precursors to form a polyurethane foam.