US2975955A

US2975955A - Heat sealable stepped end bag

Info

Publication number: US2975955A
Application number: US810079A
Authority: US
Inventors: Thomas M Mccurry
Original assignee: Union Bag and Paper Corp
Current assignee: Union Bag and Paper Corp
Priority date: 1959-04-30
Filing date: 1959-04-30
Publication date: 1961-03-21
Anticipated expiration: 1978-03-21
Also published as: CH361189A

Description

March 21, 1961 T. M. MCCURRY HEAT SEALABLE STEPPED END BAG Filed April 50, 1959 llllllllllill\lllllnh. llllllllll 1.1.11....11'1'...lill-1.."

JNVENTOR. 7//0/7/95 M /Vc WH/PK HEAT SEALABLE STEPPED END BAG Thomas M. Mc'Curry, Savannah, Ga., assignor to Union Bag-Camp Paper Corporation, New York, N.Y., a corporation of Virginia nues Apr. so, 1959, ser. No. 810,079

6 claims. (ci. 229-55) The present invention relates to improvements in bags. More particularly it pertains to a multiwall paper bag having a heat scalable inner ply.

At present hygroscopic, deliquescent, corrosive, semiliquid and other hard-to-protect products are packaged and shipped in pails, drums and cans. Such containers are expensive, require large storage and shipping space, and are more costly during shipping because of their weight and bulk. It is an object of the present invention to provide a bag which overcomes such disadvantages but is just as efficient in use.

It is a further object of the invention to provide a at bag constructed in the form of a tube Vfrom two to six plies of paper and designed to hold up to 100 pounds of bulk product. The inner ply is coated with or formed of polyethylene or any other heat Sealable material. Furthermore, depending on the product being packaged, the plies can be made up of various combinations of paper, paper and foil, or polyethylene coated paper and foil.

It is a further object of the invention to provide a heat sealable paper bag having the various plies stepped or offset so that the inner ply is exposed to take a direct heat seal application. Previously it was impractical to heat seal the inner ply of a multiwall bag because the seal had to be applied through `all the plies. These plies provided an insulating barrier which prevented heat seal ing at acceptable commercial speeds. In addition, the plies so dissipated the heat that it was virtually impossible to form a clean, straight heat seal line. With the construction of the present invention it is possible to heat seal the inner ply rapidly in a straight line. The entire lip can then be folded over and pasted to the youter face of the bag so that no pressure is exerted on the heat seal line.

It is another object of the invention to provide a bag which will form a completely heat sealed, liquid and airtight package which eliminates moisture vapor transmission in either direction, which is simple in design and rugged and strong in construction, and which is etlicient and economical for its intendeduse.

Other objects of the invention will in part be obvious and will in part appear hereinafter.,

The invention accordingly comprises an article of manufacture possessing the features, properties, and the relation of elements which will be exemplified in the article hereinafter described and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:

Figure 1 is a plan View of the tube of the present invention with the inner ply opened up to show the longitudinal seam;

Figure 2 is a plan view of the flat tube of the present invention;

Figure 3 is a plan view ofthe tube of Figure 2 with the top and bottom lips folded and pasted to the outside of the bag;

Figure 4 is a plan view of the bag of Figure 3 with a strip of tape secured over the closure at each end;

Figure 5 is an enlarged cross-sectional View on the line 5--5 of Figure 1;

Figure 6 is an enlarged cross-sectional View showing the bottom closure of an opened bag;

Figure 7 is an enlarged cross-sectional View showing a filled bag on the line 7-7 of Figure 4.

Referring more particularly to the drawing, there is shown in Figures 1 and 2 a tube 10 formed from four plies of paper with the outer plies designated collectively Ias 11. Each of the outer plies, 11a, 11b and 11e, has a longitudinal seam formed by adhesively securing together the overlapped longitudinal edges. The inner ply 12 is of heat sealable material and can be made of various combinations. For example, if polyethylene is the heat scalable material, it can be an unsupported iilm, it can be laminated to a sheet of paper, or it can be a layer of foil laminated with polyethylene to a layer of paper with another coating of polyethylene over the foil. Although it is possible to form a waterproof longitudinal seam by overlapping the longitudinal edges of the inner ply and securing them together, it is much more effective and safe to heat seal the two heat scalable faces of the inner ply in the form of a tin 13 and then turn such iin llat against the ply, as is shown in Figure 1. The Various plies are spot pasted to keep them in position with respect to each other. f

It will be seen in Figures 1 and 2 `that the tube 10 has the plies stepped or offset at each end so that the outer plies of one face of the bag extend beyond the inner ply which, in turn, extends beyond the outer plies of the other face of the bag. Although each end of the tube can be stepped toward the same face, it avoids waste during the manufacture of the tubes to have one end stepped toward one face with the other end stepped toward the other face, as is shown herein. By stepping the end of the bag Ias described, the inner ply 12 is exposed to take a direct heat seal application. This permits heat sealing such ply much more rapidly than would be possible if the heat had to be applied through the outer plies. Furthermore, the rapid application of heat to the exposed ply results in 'a clean, straight heat seal line 14 rather than a ragged heat seal over a large area with the faces of the ply joined together below the eventual fold line.

After the inner ply 12 has been heat sealed as described, adhesive 15 is applied to the extended lip of the outer ply and the entire lip, consisting of such outer ply and the heat sealed inner ply, is folded over along the top edge 16 of the short face and secured to such face. It will be apparent that any pressure will thus be exerted against the fold line rather than against the heat seal. A strip of tape 17 is then adhesively secured yover the folded down lip and adjacent face and the ends of the tape are turned over the side edges of the bag and secured to the opposite face, as shown in Figure 4. This insures a neat and tight closure. In some cases, where there are few plies or they are of light weight, the pasted turned down; lip will provide a suflicient and effective 4closure without the use of the tape.

Figures 6 and 7 show in cross-section the positions of the various plies and tape in both the top and bottom closures. The bag manufacturer heat seals the bottom of the tube, pastes and folds over the lip of the outer ply, and applies gummed tape over the folded lip. The bag user receives the bag in this condition, lls the bag with his product, then closes the top of the bag with the same closure as is on the bottom. This results in a bag in which the factory closure and the customer closure are the same thereby giving a neat, attractive package. One

method of forming the closures herein described is disclosed in the pending application of William C. Kerker, Serial No` 810,072, tiled April 30, 1959.

Thus it will be apparent that the herein disclosed invention provides a new bag which is completely heat sealed, is` virtually airtight, eliminates moisture vapor transmission, costs less per unit than bre or steel drums, pails or cans, is strong, requires a minimum of Warehouse space for empty or filled bags, is disposable and eliminates a return program, has less tare Weight, and is vermin proof, grease proof, `acid resistant and not subject to oxidation.

Since certain changes may be made in the above article, and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A heat sealable'stepped end bag comprising outer paper plies and a heat scalable inner ply formed into a tube, a closure at one end of the tube forming a bottom, the opposite end khaving the outer plies of one face of the tube, the inner ply and the outer plies of the opposite face each extended beyond the other in stepped relationship with'tlie inner ply exposed, said inner ply being heat seal-able adjacent the top edge of said bag to close said tube. v

2. A heat scalable stepped end bag comprising an outer paper ply and a heat scalable inner ply formed into a tube, a closure at one end orf the tube forming a bottom, thel opposite end having the outer ply of `one face of the tube, the inner ply and the outer ply of `the opposite face each extended beyond the other in stepped relationship, said inner ply being heat sealed along a line adjacent the top edge to close the tube, said inner ply and extended outer ply being folded over along -a line below the heat seal line and secured to the opposite face.

3. The bag of claim 2 in which a tape is adhesively secured over the extended outer ply and the said opposite face.

4. A heat scalable stepped end bag comprising outer paper plies and a heat sealable inner ply formed into a tube, a bottom closure, the top end having the outer plies of one vface of the tube extended beyond the inner ply and the inner ply extended beyond the outer plies of the opposite face in stepped relation, -a heat seal band across the extended edge of the inner ply closing the tube, said inner ply and extended outer ply being fold-ed over along a line below the heat seal band yand secured to the opposite face.

5. The bag of claim 4 in which a tape is adhesively secured over the extended outer ply and the said opposite face.

6. A heat scalable stepped end bag comprising outer paper plies and a heat scalable inner ply formed into a tube, each end having the outer plies of one face of the tube extended beyond the inner ply and theinner ply being `extended beyond the outer plies of the opposite face in stepped relation by providing longer outer plies than the heat-scalable inner ply extending beyond said inner ply at said one face and shorter outer plies than said inner ply at said opposite face, a heat seal band across the inner ply adjacent the end of the tube closing the tube, the inner ply and extended outer plies being folded over along a line below the heat seal band and secured to the opposite face.

References Cited in the tile of this patent UNITED STATES PATENTS 2,015,199 Sparks Sept. 24, 1935 2,093,979 Farmer Sept. 21, 1937 2,114,623 Bergstein Apr. 19, 1938 2,298,421 Salsberg Oct. 13, 1942 2,387,812 Sonneborn Oct. 30, 1945