Patent Application
20170036820
1. Field of the Invention
The present Invention relates to plastic “deli” bags and more particularly to a “deli” bag formed of extra thin sheets of high density polyethylene which has increased strength and the ability to keep food products fresh longer, and to a method of manufacturing same.
2. Description of Prior Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
“Deli” bags made of low density plastic sheet materials are well known in the art. The bags are used for various applications including packaging meat or other products purchased from retail food establishments. The bags are used to transport the food products to the home of the purchaser and to preserve of the contents once at home. Slide or zipper-type closures are commonly provided to seal the open mouth of the bags to preserve freshness.
Conventional “deli” bags are fabricated using a three step process in which the tracks for the slide or zipper closure are extruded as part of the plastic film by the blow film machine in the extrusion process. The bags are printed two at a time and then the slide or zipper is installed.
However, that manufacturing process is relatively slow. The time period over which the bags produced by that process can maintain freshness is limited. Further, the strength of the bags many not be adequate for all applications.
It is therefore a prime object of the present invention to provide a “deli” bag with extra thin walls and increased strength.
It is another object of the present invention to provide a “deli” bag which is capable of maintaining the freshness of its contents for a longer time period than conventional bags.
It is another object of the present invention to provide a “deli” bag formed of high density polyethylene.
It is another object of the present invention to provide a “deli” bag in which the walls of the bag are no more than 0.0008 inch thick.
It is another object of the present invention to provide a “deli” bag using a manufacturing process which is more efficient and less expensive than conventional manufacturing processes.
It is another object of the present invention to a method of manufacturing a “deli” bag in which either top loaded or bottom loaded bags can be produced.
It is another object of the present invention to provide a method of manufacturing a “deli” bag in which the closure tracks are created after the bags are formed.
It is another object of the present invention to provide a method of manufacturing a “deli” bag in which the closure tracks are created after completion of the printing process.
It is another object of the present invention to provide a method of manufacturing a “deli” bag same in which four production lines of “deli” bags can operate simultaneously.
In general, the above object are achieved by the present invention which is directed to a method of manufacturing plastic “deli” bags including extruding first and second aligned sheets of high density polyethylene film. The sheets are formed into plastic bags films by heat sealing the aligned sheets along the sides and either the top or bottom edges of each bag. Mating closure tracks are created proximate the non-sealed top or bottom of each bag after the bag is formed. A closure member is then installed to co-operate with the closure tracks to open and close the bag.
In accordance with another aspect of the present invention, a method is provided for manufacturing plastic “deli” bags. The method includes extruding aligned sheets of plastic film each having a thickness of no more than 0.0008 inch. The bags are formed from the aligned sheets by heat sealing the side and either the top or bottom edges of each bag. Mating closure tracks are created proximate the non-sealed top or bottom of each plastic bag, after the bag is formed. A closure member is installed to co-operate with the closure tracks to open and close the bag.
The step of installing the closure member can include installing either a slider member or a zipper member.
The manufacturing method further includes printing indicia on each of the bags. Preferably, four bags in side-by-side relation are printed at the same time.
The step of extruding aligned sheets of film includes extruding a first set aligned film sheets with a width at least as wide as two side-by-side “deli” bags. It also includes extruding a second set of aligned film sheets with the width at least as wide as two side-by-side “deli” bags. The step of printing indicia includes arranging the first set of aligned film sheets and the second set of aligned film sheets in side-by-side relation such that indicia for four “deli” bags can be printed at the same time.
In accordance with another aspect of the present invention, a plastic “deli” bag is provided including first and second aligned sheets of high density polyethylene film sealed along the sides and either the top or bottom edges. The bag has mating closure tracks proximate the non-sealed top or bottom edge thereof. A closure member is provided to co-operate with the closure tracks to permit the bag to be opened and closed.
In accordance with another aspect of the present invention, a plastic “deli” bag is provided including first and second aligned plastic sheets with a thickness of no more than 0.0008 inch sealed along the sides and either the top or bottom edges. The bag has mating closure tracks proximate the non-sealed top or bottom edge thereof. A closure member is provided to co-operate with the closure tracks to permit the bag to be opened and closed.
The bag closure member is either a slide member or a zipper member.
To these and to such other objects that may hereinafter appear, the present invention relates to a “deli” bag with extra thin walls and increased strength, and a method of manufacturing same, as described in detail in the following specification and recited in the annexed claims, taken together with the accompanying drawings, in which like numerals refer to like parts and in which:
The bag shown in
The interior surfaces of front wall 10 and rear wall 12 proximate open mouth 14 of the bag are provided with opposing, mating closure tracks 22. A closure member 24, in the form of a slide or a zipper, is installed such that movement of the member along the top of the bag will open and close mouth 14.
The walls 10 and 12 are formed of high density polyethylene, a material with a high strength-to-density ratio. It has stronger intermolecular forces and higher tensile strength as compared to low density plastic sheets. It is also harder, more opaque and can withstand higher temperatures. At the same time, the material is resistant to many solvents.
Further, the properties of high density polyethylene keep food situated within the bag fresher than conventional plastic materials. Accordingly, it is an ideal material for use in “deli” bags.
In the sealing stage, the aligned sheets 30 and 32 pass beneath a heated reciprocating platen 40 in order to form bags A. The platen heat seals the aligned sheets to join the side edges 18, 20 and bottom 16 of each bag. As these bags are top loading bags, the edges of the walls which define mouth 14 are not sealed together.
The bags then move along conveyer 38 to a print stage where they pass beneath one or more a print rollers 42 (only one of which is shown). The print rollers deposit ink in the form of text and/or images (such as the logo of the store in which the bags are used) on the exterior surface of the front wall of each bag.
After printing, the bags move through a process stage in which the bags are separated from each other by a blade and at the same time the closure tracks 22 are created. This is accomplished using a reciprocating platen 44 which includes a downwardly directed blade 46 and elongated heated protrusions 48 extending from the bottom surface. Thus, in the process of the present invention, the closure tracks are created after the bags are formed.
In the last stage of the manufacturing process, each of the separate bags A moves off the end of conveyor 38 and onto a platform 50 to form a stack of bags A. As each of the bags is situated on the stack, a closure member 24 in the form of a plastic slide or zipper is installed on the top of the bag such that the non-sealed mouth 14 of the bag can be opened and closed.
Referring now to
As the separated bags move off the end of conveyor 38 and onto a stack of bags accumulating on a platform 50, a closure member 24 is installed on each bag. The stacks of bags A typically contain 50 or 100 bags each and are now ready for packaging and shipment.
While only a single preferred embodiment of the present invention has been disclosed for purposes of illustration, it is obvious that many modifications and variations could be made thereto. It is intended to cover all of those modifications and variations which fall within the scope of the present invention, as defined by the following claims.
