Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1992-01-09
1993-01-26
Welsh, Maurice J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
249 661, 249117, C08G 1814
Patent
active
051823136
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.
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Burwell, J., The "Bunmaster" a New Concept in Discrete Bun Production, Society of Plastic Industry, Inc., Polyurethane Division, Proceedings of the 27th Annual Conference, pp. 129-146 (1981).
Volland, R., Lindsey, J. and Schuberth, W., A Technical Update on MDI Based Molded Flexible Foams, Society of Plastic Industry, Inc., Polyurethane Division, Proceedings of the 28th Annual Conference, pp. 86-91 (1984).
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