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US 4,913,761 AGranted
Method for severing and sealing thermoplastic materials
AssigneeThe Dow Chemical Company
InventorsPatrick M. Russell, Roger K. Pihlaja, Timothy R. Woods
Life of this patent
Estimating the term…
Abstract
A process and apparatus for severing and simultaneously sealing a plurality of plies of thermoplastic material to form bags for storing foods therein is provided. A severing and sealing element fabricated from a long range ordered alloy is used. The use of that alloy provides increased element life at higher operating temperatures while significantly reducing odor and off-flavor problems in the bags.
Claims10
A process for severing a plurality of plies of a thermoplastic material and simultaneously sealing the severed margins thereof comprising the steps of:
- (a) selecting a cutting and sealing element having a length at least as long as the section of thermoplastic material to be severed and sealed,
- (b) heating said element to a temperature above about 1300 degrees F., the element having at about 1500 degrees F. a creep of less than about 2.times.10.sup.-5 hr.sup.-1 at about 4.5 ksi, an oxidation resistance in air of less than about 10 grams/cm.sup.2 per 300 hours exposure, a fatigue resistance of about 10.sup.7 cycles at about 10 ksi, and a tensile yield strength of greater than about 50 ksi, and
- (c) bringing said element into proximity with said thermoplastic material to sever said plies and form a sealed edge.
Dependencies are inferred from the claim text.