US2952399A

US2952399A - Multiwall bag construction

Info

Publication number: US2952399A
Application number: US519874A
Authority: US
Inventors: Robert F Searle
Original assignee: Arkell and Smiths
Current assignee: Arkell and Smiths
Priority date: 1955-07-05
Filing date: 1955-07-05
Publication date: 1960-09-13
Anticipated expiration: 1977-09-13

Description

Sept. 13, 1960 R. F. SEARLE MULTIWALL BAG CONSTRUCTION Filed July 5, 1955 INVE NTOR figzfierz Jearle 2 4e,

M 0! MW ATTORNEYS I l I United States Patent MULTIWALL BAG CONSTRUCTION Robert F. Searle, C'anajoharie, N.Y., assignor to Arkell and Smiths, a corporation of New York Filed July 5, 1955, Ser. No. 519,874

3 Claims. (Cl. 229-66) This invention relates to the manufacture of multiwall bags wherein the paper adjacent the mouth of the bag is so weakened that the top of the bag may be readily torn ofi? by hand in one smooth, even movement.

The type of multiwall bag to which this invention relates is a so-called gusseted bag which is ordinarily sealed shut by means of a line of stitching running across the top of the bag. In theory, such a bag is opened by unraveling the stitching, but this is difficu-lt to do and as frequently happens it is necessary to get a knife or a pair of scissors and cut the top of the bag off below the line of stitching.

With bags made in accordance With my invention, the top may be readily torn oil by hand in one smooth, even movement. This effect is achieved by so weakening the paper at one side of the bag adjacent its mouth that the paper can be readily torn by hand but the paper is weakened in such a way that there is no danger of leakage, even if the bag is filled with fine powder. Weakening the bag so that it will readily tear is achieved by means of a small slit positioned at the side of the bag and by means of a plurality of small holes which assist in leading the tearing from the slit up to the line of sewing across the top of the bag.

As is known, the strongest part of a multi-wall bag and the most difiicult part to tear is located in the area of the gusset at the side of the bag where the paper is doubled over on itself. I have found that the only satisfactory way of tearing through the crease line of the gusset so that tearing will start at a designated spot is to cut a slit all the way through the layers of paper in the gusset crease lines. In this way I achieve accurate control of tearing so that it starts at a predetermined point and once tearing is started the momentum of the tearing movement is such that tearing may be readily sustained and controlled by means of the line of small holes, which lead the tearing up towards the line of stitching across the top of the bag. As a result, in the structure of my invention, tearing is rigidly controlled along a predetermined line and the bag when torn open presents uniformly and evenly torn edges which are of great advantage for emptying the contents of the bag. If tearing is not rigidly controlled there is a tendency for it to go off on a tangent and spiral down the side wall of the bag, which may result in loss of product.

A surprising thing about the structure of my invention is that although I actually slit the paper of the bag and punch small holes in it, none of the contents leak from the bag during shipment and storage. I believe that this is a result of two factors. First of all I locate the weakened portion of the bag in the area of the gusset adjacent the mouth of the bag where the paper is strongest and as a result there is no tendency to increase the chance of the bag splitting open when it is handled. The second factor is that there are two or more plies of paper in the side wall of the bag and I believe that the displaced fibers in successive layers of paper tend to close the slit ICC and holes sufiiciently so that no leakage occurs. In any event, bags made in accordance with my invention filled with lbs. of cement were subjected to rigorous tests and none of the bags failed and there was :no leakage of contents from the bags.

My invention may be readily understood by reference to the accompanying drawings in which Fig. l is an isometric view of the top portion of a multiwall bag tube illustrating the structure of my invention;

Fig. 2 is a front elevational view of the bag tube shown in Fig. 1 which is closed on top by means of a separate strip of paper which is folded over the mouth of the bag and sewed in place to close the open bag mouth; and

Fig. 3 illustrates the way in which the top of the bag of Fig. 2 may be torn oil by hand in accordance with my invention.

Referring now to the drawings, 10 is a top portion of a multiwall bag tube having two or more plies of paper or other bag forming material in the side wall of the tube. Along each side of the tube is a gusset 12 which is formed by folding a portion of the side wall inwardly into the bag tube and the infolded paper is then sharply creased to hold it in position. In use, the bag tube is filled through the open mouth and then closed by means of a line of stitching 14 across the top of the bag. A strip of paper 16 is ordinarily folded over the mouth of the bag and pasted down over the line of stitching on both sides of the bag. If desired, the strip of paper may be applied before the bag is sewed and the paper 16 is then caught in the line of stitching. If this is done no pasting is necessary.

In accordance with the present invention a small slit 18 is cut through the paper of the two outside crease lines 19 of gusset 12. Slit 18 must be deep enough to completely cut through all of the plies of paper in both crease lines 19 and in general a slit that extends inwardly into the side wall of the bag about A; to A of an inch and preferably about 7 inch is suflicient. Slit 18 may be made deeper than this, but a deeper slit serves no useful purpose and it only tends to weaken the paper in the side wall of the bag. Slit 18 terminates at a point removed from the line of stitching acros the top of the bag but in proximity thereto and at a point adjacent to a line of a plurality of holes 20 which lead inwardly and upwardly away from the slit towards the line of stitching 14 across the top of the bag. The line of holes 20 tenninates approximately at the line of stitching 14. Holes 20 are about the size of the holes formed by the needle employed for sewing the bag shut and as in the case of slit 18, holes 2%) preferably penetrate through all of the plies of the paper in the gusset and both side walls of the bag. Space 22 between each hole 20 and. between slit 18 and the hole 20 adjacent the slit may be the same size as the spaces between the holes in the line of stitching 14 across the top of the bag. With ordinary sewing machines now in use the holes in the line of stitching across the top of the bag that close the bag tube are approximately to of an inch in diameter and the space between the periphery of adjacent holes is about of an inch. Best results are achieved in carrying out my invention by making holes 20 about the same size and about the same distance apart as those in the line of stitching 14 across the top of the bag. It will be understood, however, that any dairable arrangement and spacing of holes 20 may be used as long as the paper between the holes can be torn away by hand and as long as there is no tendency for the bag to leak during shipment and storage.

It can be readily appreciated that slit 18 and holes 20 weaken the paper in the side wall of the bag, but I have found that the paper in the gusset area adjacent line of stitching 14 is strong enough to withstand such weakening without increasing the chance of the bag splitting open during the handling incident to shipment and storage. Referring to the drawings, it will be seen that slit 18 is located below the line of stitching 14 across the top of the bag and the slit should be located within the area covered by the folded strip of paper 16 with the result that the slit and series of holes are concealed by the paper strip. Slit 18 may be located immediately adjacent the line of stitching 14, but it must be located far enough down to provide a good finger grip at the top of the closed bag above the slit. If desired, slit 18 may be directed upwardly at an angle toward the line of stitching 14.

As previously described hereinabove, holes 20 form a connecting line between slit 18 and the line of stitching 14, and in order to have the paper tear smoothly and evenly it is impotrant that the space between the last hole 20 and a hole in the line of stitching is no greater that the spacing between any two adjacent holes 20. Best results are achieved when the last hole 20 is positioned just below the line of stitching with the top of hole 20 in line with the bottom of the holes in the line of stitching 14. When this is done the tearing is evenly and smoothly led into the line of stitching across the top of the bag.

If desired holes 20 may be positioned in a straight line across the bag parallel to the line of stitching 14 but best results are achieved when the holes are directly upwardly towards the line of stitching as shown in the drawings.

It will be understood that the bag tube is sewed shut after slit 18 and holes 20 are positioned in the tube, but the location of holes 20 relative to the line of stitching presents no problem since for any given filling operation the line of stitching 14 across the bag is in approximately the same location on successive bags, and any small change in location of the line of stitching between successive bags may be compensated for by locating the top of the last hole 20 in line with the place where the bottom of the holes in the line of stitching will ordinarily cross the top of the bag for a given sewing operation.

With bags made in accordance with my invention it is only necessary to grasp the top of the bag tightly between the thumb and forefinger and by giving it a quick jerk upwardly the paper will start tearing at slit 18 and with the momentum of the tearing movement thereby obtained, tearing will progress smoothly and evenly along the line formed by holes 20 and stitching 14 across the top of the bag. In the usual bag construction the separate strip of paper 16 at the top of the bag projects out beyond the side edge of the bag and the projecting portion of the strip of paper may be used as a handle for tearing off the top of the bag.

It will be understood that I intend to cover all changes and modifications of the preferred embodiment of my invention herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope of'my invention.

What I claim is:

1. In a bag of the type having walls of'a'pluralit'y of plies of paper having a portion of the wall along each side folded inwardly and sharply creased to form a gusset with two outside crease lines that extend along each side of the bag from top to bottom, a separate strip of paper folded over the top of the bag which covers the open mouth thereof and which projects out beyond one of the side edges of the bag and a line of stitchingp'ositioned across the top of the bag adjacent the open mouth thereof which passes through the strip of paper to attach it to the exterior of both side walls of the bag so that the strip of paper is held in place to close the open mouth of the bag, a slit positioned in each of the two outside crease lines of the gusset below the line of stitching at that side of the bag from which the separate strip of paper projects which slits are located in spaced relationship to the line of stitching but adjacent thereto within the area at the top of the bag covered by said separate strip of paper, said slits penetrating deeply enough into the side wall of the bag to cut through all of the plies of paper in the two outside crease lines of the gusset but only far enough to form an opening in the inner ply small enough so that substantial le'aka'ge'of product will not occur, each of said slits terminating below the line of stitching across the top of the bag and in proximity thereto, and a plurality of spaced holes punched through all of the plies of paper in the gusset and side wall of the bag to form a series of holes that extend in a'line from the slits up to the line of stitching across "the top of the bag to control tearing of the paper plies so that once tearing is started at the slits the tearing will continue along the line of said holes and thereafter follow the line of stitching across the top of the bag whereby the top of the bag may be torn off by hand by jerking npwardly on the projecting end of the strip of paper which covers the open mouth of the bag. 7

2. A structure as specified in claim 1 in which the slits are positioned at an angle relative to the line of the side edge of the bag sloping inwardly and upwardly towards the line of stitching across the top of the bag.

3. A structure as specified in claim 1 in which the slits extend inwardly into the wall of the bag from about A; to A of an inch.

References Cited in the file of this patent UNITED STATES PATENTS 1,155,740 Lacroix Oct. 5, 1915 2,099,425 Goodman Nov. 16, 1937 2,189,431 Moore Febu'6, 1940 FOREIGN PATENTS 481,327 Canada Feb. 26, 1952 709,750 Great Britain June 2, 1954 865,561 France Mar. 3, 1941