Pactiv Corporation

Tenneco Packaging Inc.

Robert T Maddock

William P Belias

Edward M Bullard

An apparatus and method for heating and cooling a polymer structure employs a tube structure. The tube structure includes a conductive tube and a conductive strip. The tube is composed of a first conductive material having a first electrical resistivity, and the strip is composed of a second conductive material having a second electrical resistivity less than the first resistivity. The strip is connected to only a portion of an outer surface of the tube and extends along a length of the tube. In the method, an impulse of electric current is passed through the tube structure until the strip is heated to a predetermined sealing temperature. The strip and the polymer structure are brought into contact with each other for a dwell time sufficient to generate a heat seal in the polymer structure. A cooling medium is passed through the tube to cool the strip to a predetermined release temperature that facilitates release of the strip from the polymer structure.

Apparatus for high-speed heating and cooling of a polymer

Folded thermoplastic bag structure

A method of forming a plurality of easy to open handle bags including the steps of providing a flattened tube of thermoplastic material oriented in a generally longitudinal direction. The flattened tube has a first longitudinal side edge and a second longitudinal side edge, a transverse lower heat seal, and a transverse upper heat seal. The tube also has first, second, and third sections. The second section being disposed between the first and third sections. The first section is joined to the second section along a generally longitudinal first fold line. The second section is joined to the third section along a generally longitudinal second fold line. The second section is cut along a generally transverse first cut line extending between the first and second fold lines. The first section is folded over the second section along the first fold line. The third section is folded over the previously folded-over first section along the second fold line such that the first, second, and third sections overlap one another. The overlapped first, second, and third sections are cut along a generally longitudinal second cut line that intersects the first cut line, the first fold line, and the second side edge at one end and intersects the upper heat seal at the other end. The overlapped first, second, and third sections are then cut along a generally longitudinal third cut line that intersects the first cut line, the second fold line, and the first side edge at one end and intersects the upper heat seal at the other end.

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Ionia, NY, United States of America

Robert T Maddock