The Dow Chemical Company

Timothy R Woods

R Douglas Behr

Fred Stevenson

Patrick M Russell

Roger K Pihlaja

A disposable or reusable and reclosable gussetted plastic bag capable of being compactly stored as a food container in freezers, yet capable of standing with an upright spout in a microwave oven for non-spill thawing and cooking of food contained in the bag. The bag is formed of two wing-shaped pouches on either side of the upright spout. The bag preferably has inner and outer skin layers of different heat sealing temperatures so that peripheral sealing is effected only with the inner skin layers, allowing the wing-shaped pouches to be formed out of a gussetted bottom without sealing of the outer skin layers of the gusset walls facing one another. Two pairs of relief seals are located adjacent each gusset joint at both edges of the bag. Each seal is positioned 45.degree. off the gusset joint and preferably has a radius shape. The heat seals are formed by applying heat adjacent each gusset joint with a hot bar or other heat sealing device following formation of the bag.

Gussetted plastic bags having relief seals and method of making same

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.

Method for severing and sealing thermoplastic materials

A disposable or reusable and reclosable gussetted plastic bag capable of being compactly stored as a food container in freezers, yet capable of standing with an upright spout in a microwave oven for non-spill thawing and cooking of food contained in the bag. The bag is formed of two wing-shaped pouches on either side of the upright spout. The bag preferably has inner and outer skin layers of different heat sealing temperatures so that peripheral sealing is effected only with the inner skin layers, allowing the wing-shaped pouches to be formed out of a gussetted bottom without sealing of the outer skin layers of the gusset walls facing one another. Two pairs of relief seals are located adjacent each gusset joint at both edges of the bag. Each seal is positioned 45.degree. off the gusset joint and preferably has a rounded peak shape. The heat seals are formed by applying heat adjacent each gusset joint with a hot bar or other heat sealing device following formation of the bag.

A process and apparatus is provided for cutting multiple plies of thermoplastic material having thickened sections, such as defined by cross-sections of matable parts of a zipper closure formed in the material, and for concurrently sealing the severed margins of the material which includes sealing the severed zipper closure portions thereof. The process and apparatus perform the operative steps of: first, preblocking the thickened material adjacent to the zipper closure portions of the material in areas thereof to be severed and sealed; then, applying heat and pressure to the thickened material and remaining sections of the material in those areas to render the material tacky and temporarily stick the multiple plies together in those areas; and, thereafter, contacting those areas of the material with a heated cutting and sealing element in order to sever all of the multiple plies and seal the severed margins thereof. Further, after the application of heat and pressure, the zipper closure portions of the material in the areas thereof to be severed and sealed are preheated. Also, after the margins of the multiple plies of material are severed and sealed, pressure is applied to the zipper closure portions at the severed and sealed margins to ensuring sealing thereof.

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Midland, MI, United States of America

Timothy R Woods