Patent ID: 8215085

Claim:
A method of preparing a web of flexible material for production of receptacles for packaging, the method comprising the steps of: feeding a web of flexible material past a succession of stations while carrying out operations on the web, including defining blanks for receptacles having walls and tabs, including flanges, by creating fold lines in the web by at least partially cutting or scoring through the web of flexible material, and preforming lines of cut in the blank to define notches between adjacent flanges, then, laminating a film of heat-sealable plastics material to a face of the web of the flexible material to provide a heat-sealable surface for bonding tabs of each blank together to form seams between adjacent walls, and bridging the adjacent notches by laminating the film of heat-sealable plastics material to the web, whereby the blanks, when severed from the web, can be erected to form receptacles having openings to receive items to be packaged, with the out-turned flanges extending along sides of the opening into the receptacle being heat-sealed through the film laminated to the surface of the blank to a lid, thereby to close the receptacle; wherein laminating the film of heat-sealable plastics material to the web and bridging the notches defined between the adjacent flanges serve to assist in forming a hermetic seal for the receptacle between the flanges.