Process for making foam-in-form polyurethane foam buns and apparatus therefor

摘要

An improved method for manufacturing a foam-filled polyurethane foam bun from foam particles having uniformly dispersed therewith large amounts of solid material bonded together with new polyurethane foam is described. The method comprises uniformly applying a liquid flexible polyurethane foam-forming material to a dispersion of foam particles and solid material to provide a blend, distributing the blend within a mold, and foaming and curing the foam-forming material by a plurality of steaming steps wherein the mold is flipped from a first to second position between steaming steps. The foam buns have a uniform density gradient. Foam buns are disclosed having a variation in density across the foam bun. There is also disclosed an improved char-forming foam obtained as a result of using boric acid in the foam-forming formulation.