C-i-l, Inc.

Imperial Chemical Industries Limited

Charles R Murray

John G Barnes

Ray E Harrison

A thermoplastic heavy duty shipping bag having walls formed of cross-laminated outer plies of uni-axially oriented polyethylene and inner walls of low density polyethylene, heat sealed thereto. The bag provides improved puncture and snag resistance.

Shipping bag

A cold-drawn unbalanced biaxially oriented linear low density polyethylene film having a transverse direction draw ratio selected from greater than 1 to less than 3 and a machine direction draw ratio of less than 6 but greater than the transverse direction draw ratio. The film has enhanced tensile and puncture resistance while maintaining acceptable tear properties and is used for shipping sacks.

Thermoplastic sack

A shipping sack having walls formed of uni-axially oriented linear low density polyethylene film wherein said film is produced by blowing and cold drawing said polyethylene at a draw ratio to blow ratio of greater than 1:1, preferably, between 2:1 and 5:1. The sack can be used as a tubular shipping sack for bulky, lightweight material or, if optionally provided with a double inner film of low density polyethylene, as a heavy duty sack. The sacks have improved physical properties.

A thermoplastic shipping bag having a thermoplastic inner ply comprising a mesh which permits the packaging of finely powdered materials without releasing unacceptable levels of powders to the atmosphere during or after filling and without requiring significant modification to packaging systems used to fill and process multi-wall paper shipping bags.

Thermoplastic bag

A polyethylene shipping bag having an internal nylon barrier coating which permits packaging of materials which normally migrate through polyethylene. The coating is flexographically applied from a nylon solution in a lower aliphatic alcohol with up to 15% water to a polyethylene film which has been previously treated to make it receptive to printing ink. The bag may be single ply or double ply and may have a filling valve.

Method of making polyethylene shipping sack with flexographically

In the production of plastics bags, especially valved bags, from a web of plastics material by folding in the side margins of the web to form overlapping panels which are then longitudinally heat-sealed together for a major portion of one bag length, and then heat-sealing the web transversely and severing the web at intervals to produce individual bags, the two overlapping panels are heat-sealed together by forming two longitudinal seals which partially overlap to provide a forward longitudinal seal and a rear longitudinal seal with respect to the direction of travel of the web, the rear longitudinal seal of each bag being formed simultaneously with the forward longitudinal seal of the adjacent following bag. The apparatus comprises a pair of heat-sealing elements equipped for simultaneous operation and arranged for forming the rear seal in one bag and the forward seal in the following adjacent bag. The two elements may be a fixed distance apart, and at least one has suitably a hairpin shape.

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Toronto, Canada

Charles R Murray