Process and apparatus for sealing

Claim 1

THE PROCESS OF JOINING TOGETHER MARGINAL PORTIONS OF SHEETS OF FILM OF BIAXIALLY ORIENTED THERMOPLASTIC MATERIAL WITH COMPRISES PLACING MARGINAL PORTIONS OF SHEETS OF THE FILM IN FACE-TO-FACE RELATIONSHIP BETWEEN ROTATABLE ROLLER MEMBERS DEFINING A CONTINOUS CLAMPING AREA AND DIVERING PORTIONS DEFINING AN OPENING LONGITUDINAL CAVITY WITH OUTER FREE EDGES OF SAID MARGINAL PORTIONS EXTENDING FROM SAID OPEN CAVITY AND SPACED A PREDETERMINED DISTANCE THEREFROM, COOLING SAID CLAMPING MEMBDRS WHEREBY SAID CAVITY DEFINING PORTIONS ARE COOLED, APPLYING HEAT TO THE EXTENDING MARGINAL PORTIONS OF SAID FILM TO MELT SAME BACK INTO SAID OPEN COOLED CAVITY, CONDUCTING EXCESS HEAT AWAY FROM THE CLAMPING MEMBERS TO RESTRICT THE MELTING TO THE FREE MARGINAL PORTIONS IN AND EXTENDING FROM SAID OPEN CAVITY WHEREBY THE SHEETS CLAMPED BETWEEN SAID CLAMPING MEMBERS ARE PROTECTED AGAINST DISTORTION FROM THE HEAT AND THE SIDES OF SAID MELTED MATERIAL IN SAID CAVITY ARE COOLED AND SOLIDIFIED, DISCONTINUING THE APPLICATION OF HEAT TO SAID THERMOPLASTIC MATERIAL IN SAID CAVITY, CONTINUING THE COOLING OF SAID MELTED THERMOPLASTIC MATERIAL WHEREBY IT SETS TO FORM A JOINT FOR THE FILM SUBSTANTIALLY OF THE SHAPE OF SAID CAVITY AND HAVING A TRANSITION ZONE THEREIN, AND THEN RVERSING THE DIRECTION OF ROTATION OF SAID ROTATABLE ROLLER MEMBERS TO RELEASE THE JOINED SHEETS FROM CLAMPED ENGAGEMENT THEREBETWEEN AND SIMULTANEOUSLY PRESSING THE RESULTING JOINT FOR THE FILM.