An insulated food serving tray or lid therefore which includes a pair of preformed thermoplastic panels bonded together about a peripheral seam to permanently encase an insulator within a chamber between the panels. At the peripheral seam area, a first panel has an outwardly extending ledge area with...http://www.google.es/patents/US4533061?utm_source=gb-gplus-sharePatente US4533061 - Food tray and lid with sealed panels and method of forming same
Food tray and lid with sealed panels and method of forming same
