Low temperature polyolefin extrusion coating process

Claim 1

IN THE PROCESS FOR THE PRODUCTION OF POLYOLEFIN EXTRUSION COATED PACKAGING MATERIALS WHEREIN POLYOLEFIN MATERIAL IS HEATED IN AN EXTRUDER AND FORCED THROUGH A DIE FOR COATING DIRECTLY ONTO A SUBSTRATE, THE IMPROVEMENT COMPRISING THE STEPS OF: (1) ADVANCING A WEB OF SUBSTRATE MATERIAL TO BE EXTRUSION COATED WITH POLYOLEFIN THROUGH AN APPLICATOR STATION WHEREIN A POLYOLEFIN ADHESION-PROMOTING COATING IS APPLIED TO AT LEAST ONE SURFACE OF THE ADVANCING WEB OF SUBSTRATE; (2) ADVANCING SAID WEB OF SUBSTRATE THROUGH A DRYING STATION TO DRY THE AFORESAID COATING; (3) ADVANCING SAID WEB OF SUBSTRATE THROUGH THE NIP OF A ROTATING POLYOLEFIN EXTRUSION CHILL ROLL AND A BACKUP ROLL; (4) EXTRUDING A WEB OF POLYOLEFIN MATERIAL THROUGH A DIE ONTO THE PERIPHERY OF THE AFORESAID CHILL ROLL, SAID POLYOLEFIN BEING EXTRUDED AT A NON-OXIDIZING TEMPERATURE ABOVE ITS SOFTENING TEMPERATURE; (5) COOLING SAID EXTRUDED POLYOLEFIN TO A FILM-FORMING TEMPERATURE ON THE PERIPHERY OF SAID CHILL ROLL; (6) OXIDIZING A SURFACE ONLY OF SAID EXTRUDED WEB OF POLYOLEFIN BY SUBJECTING THE SURFACE TO CORONA DISCHARGE TREATMENT; AND (7) ADVANCING SAID EXTRUDED WEB OF POLYOLEFIN THROUGH SAID NIP OF THE ROTATING CHILL ROLL AND THE BACKUP ROLL SO THAT ITS OXIDIZED SURFACE CONTACTS THE COATED SURFACE OF THE ADVANCING WEB OF SUBSTRATE AND THE EXTRUDED POLYOLEFIN IS FIRMLY JOINED TO SAID SURFACE OF A SUBSTRATE UPON MOVEMENT OF THE TWO WEBS THROUGH THE NIP OF SAID ROLLS.