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US 4,228,076 AGranted
Method of densifying open-celled polyurethane material
AssigneeFoam Cutting Engineers, Inc.
InventorWinslow L. Pettingell
Life of this patent
Estimating the term…
Abstract
A method of densifying open-celled polyurethane foam is provided in which heated air at a temperature between about 425.degree. F. and 460.degree. F. is circulated through a mass of the foam so as to rapidly and uniformly raise the temperature of the mass to between about 365.degree. F. and 435.degree. F., the mass is then compressed to a desired thickness while its temperature is maintained between 365.degree. F. and 435.degree. F., and the mass is then immediately permitted to cool.
Claims10
A method of densifying a mass of fully cured open-celled polyurethane foam, said method comprising the consecutive steps of:
- passing heated gaseous material entirely through the mass, the temperature of said gaseous material being in the range of about 425.degree. F. to 460.degree. F. and the velocity of said gaseous material being insufficient to destroy the integrity of the cell walls of the mass, said gaseous material being inert with respect to the polyurethane, and the period of exposure of the mass to the gaseous material being insufficient to allow charring of the mass, yet sufficient to raise the entire mass substantially uniformly to a temperature between about 365.degree. F. and 435.degree. F.;
- compressing the mass while its temperature is between about 365.degree. F. and 435.degree. F. to reduce its thickness and thus increase its density to a desired degree;
- and
- permitting the mass to cool.
1 more element
Dependencies are inferred from the claim text.