Method of making a polyethylene terephthalate laminate
AssigneeE. I. DuPont de Nemours and Company
InventorWilliam Paul Kane
Life of this patent
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Abstract
A container is provided formed from a blank made of a laminate which includes nonbrowning paperboard and at least an inner layer of substantially amorphous polyethylene terephthalate bonded to the paperboard by its own substance. A method of making this laminate is provided including the steps of heating an uncoated surface or both surfaces of the paperboard to a temperature of at least about 285.degree.F. and extruding the polyethylene terephthalate layer onto this surface or these surfaces. A method of cooking is provided including the steps of forming a container from the blank, placing food in the container and cooking the food at a temperature of up to about 400.degree.F.
Claims3
A method of making a laminate comprising:
- passing a non-browning paperboard having a pH of between 7.0 and 7.5 adjacent a heating source;
- heating an uncoated first surface of such paperboard to a temperature of at least about 285.degree.F. by means of the heating source;
- extruding a layer of polyethylene terephthalate onto such uncoated first surface of the heated paperboard, such polyethylene terephthalate having an intrinsic viscosity within the range of 0.51 to 0.85;
- and
- cooling the extruded layer of polyethylene terephthalate to solidify it and to effect a bond between the paperboard and the polyethylene terephthalate to form a 2-ply laminate.
Dependencies are inferred from the claim text.