Method and apparatus for forming articles made of polyurethane

Abstract

A method and apparatus for forming articles made of polyurethane. The apparatus includes a polyol weigh tank, an isocyanate weigh tank, an additive tank and a mix tank enclosed by a vent chamber. The vent chamber is in communication with inlet and outlet pipes to move air and fumes from the interior of the vent chamber past a filter. The apparatus further includes a containment vessel also having inlet and outlet pipes for movement of air and fumes. The containment vessel is in communication with a pump for creating a vacuum in the vessel to reduce pressure in the interior of the vessel in which a mold is placed. The method includes the steps of: creating a vacuum around a mixture of at least one polyol, at least one isocyanate and at least one additive, to lower the pressure on the mixture below atmospheric pressure as the mixture expands; allowing the mixture to expand; reducing the vacuum to increase the pressure on the mixture in proportion to any further expansion of the mixture caused by the generation of a blowing influence in the mixture; and returning the pressure to atmospheric pressure.

Dependencies are inferred from the claim text.