Method of making insulated plastic containers

Claim 1

THE STEPS IN THE PROCESS OF MAKING INSULATED RECEPTACLES WHICH CONSIST IN PREFORMING SIMILARLY SHAPED INNER AND OUTER SHELLS WITH SAID INNER SHELL BEING DIMENSIONALLY SOMEWHAT SMALLER THAN SAID OUTER SHELL TO LEAVE AN INCULATING CHAMBER THEREBETWEEN WHEN THE SAME ARE CONCENTRICALLY ASSEMBLED, PREFORMING AN INSULATION REINFORCING INSERT CONSTRUCTED OF HEAT-EXPANSIBLE INSULATING MATERIAL AND SHAPED AND DIMENSIONED TO VERY LOOSELY FIT BETWEEN SAID SHELLS, CONCENTRICALLY ASSEMBLING SAID SHELLS AND SAID INSERT, JOINING EDGE PORTIONS OF SAID INNER AND OUTER SHELLS WITH SEALING EFFECT BETWEEN THE JOINED EDGE PORTION AREAS, AND BAKING THE SHELLS SO ASSEMBLED AT A TEMPERATURE BELOW THAT AT WHICH SAID SHELLS SO ASSEMBLED AT A ABOVE THE TEMPERATURE FOR PRODUCING EXPANSION OF SAID INSULATING MATERIAL FOR PRODUCING EXPANSION OF SAID MATERIAL IN SAID INSULATING CHAMBER.