US1752292A - Paper bag - Google Patents

Description

v April 1, 1930. A. M. BATES ET AL 1,752,292

' PAPER BAG Filed Jan. 15 1926 2 Sheets-Sheet l Ade/mer/iBazses. John Evans Come/l.

IQIMM/ Patented Apr. 1,' 1930 UNITED STATES PATENT OFFICE I ADELMER M. BATES AND JOHN EVANS CORNELL, OF CHICAGO, ILLINOIS, ASSIGNORS,

BY MESNE ASSIGNMENTS, TO BATES VALVE BAG CORPORATION, OF CHICAGO, ILLI- NOIS, A CORPORATION OF NEW JERSEY I PAPER BAG Application filed January 13, 1926, Serial No. 81,091, and in Great Britain December 13, 1924.

This invention is a continuation in part of our prior application Serial No. 731,249, filed 7 August 11th, 1924, and relates to paper bags and to processes of making the same. More especially it relates to bags the walls of which are formed of a plurality of layers of paper or similar material.

The bags are particularly adapted for heavy service, that'is, for containing such heavy charges or for withstanding such rough usage as would necessitate a single wall of paper eing-of such a thickness that it would be cracked or seriously weakened by The bags are further adapted to be filled through valves and to be used to package hot materials and other substances likely to impair the strength or durability of single walled paper bags. Also, the bags may be reagily opened, repaired if necessary, and reuse Paper bags having walls composed of a single thick layer of an expensive quality of paper have been used for heavy service, such as for packaging cement, but even such an expensive paper has not given satisfaction, freqently rupturing along the side folds and elsewhere. 4 The cheaper grades of paper are entirely unsuitable for making single-walled bags for such heavy service, but can be used with entire satisfaction in our bags.

It is customary to fill cement bags through valves, the valves being made by folding in a portion of the wall of each bag, but it has been found that the heavy paper in a singlewalled paper cement bag forms such stiff valves that imperfect closures frequently result. Making the valve of a plurality of layers of paper movable relatively to each other, especially at the free edge of the valve, renders the valve more flexible and forms a more satisfactory closure,

Small bags have been made with gussets, or what are commonly called bellows-folds, there being wen known advantages in folding bags in this way; but heavy bags, such as cement bags, have -,not been folded in this way for several reasons, ofwhich may be men-- tioned the weakening of the bag caused by the additional fold lines and the reconstrucfactory valve may be formed at the end of gussets or bellows-folds tion of the valve necessitated by bellows-folds.

By making the walls of a plurality of layers of paper,- the weakening of the walls at the fold lines is largely obviated, and a satis-.

the gusset told by bending the fold in the manner described below.

While certain features of our invention are adapted for independent use, as will be more A fully stated below, the specific embodiment}! thereof illustrated comprises a valved paperbag intended for heavy service and made of a plurality of nested tubes closed at the ends'by reinforced seams and having longitudinal Further details of the invention will'bedescribed in connection with the accompany:-

ing drawings, which form. a part of this speci fication, and in which- I 4 Figure 1 is a side eleyation of ah en'lbodying our invention; Fig. 2 is an enlarged 4 section on the line 2-2 of Fig. 1, showing'the structure of the top closure; Fig. 3 is antenlarged section along the line 3-3 of Fig.' 1, partly broken away; Fig. 4 is a partial section through the top of a ba'g with the walls in the position which they occupy when the bag is filled; Figs. 5 and 6 are similar to Fig.

4, but show difierent forms of bag walls; Figs. 7, 8 and'9 are enlarged sections through different forms of reinforced seams for closing bags; Fig. 10 is a diagrammatic view illustrating the manner of cutting a continuous tube to form bag lengths; Figs. 11, 12, 13 and 14 are somewhat diagrammatic views illustrating one method of folding in a corner of the bag to form a valve; Fig. 15 is an enlarged section through the valve; Fig. 16 is a diagrammatic view illustrating the reclosing of the bag after it-has been opened, and Fig. 17' is a view of the top end of a modified form of The bag shown in Figs. 1 to 4 comprises a tubular portion 20 closed at the bottom by a reinforced seam 21 and at the top by a reinforced sea1n122. At the sides of the bag are gussets or bellows- folds 23 and 24. The bag walls are folded in atone end of gusset 24 to form a valve 25. 1

The body portion 20 is composed of a plu- 1 order to strengthen the seam where it rests.

rality of nested tubes of paper. In the drawings, four tubes are shown, although our invention is not limited to that number, as will be explained below.

Our preferred form of closure is shown in Fig. 3. As seams 21 and 22 are alike, but

is sewedat 33. This seam 33 passes through the binding strip and the intervening bag walls and firmly secures the tube walls together and closes the end of the bag. We prefer to have the adhesive extend beyond the walls of the bag and secure the two edges of the binding strip together where it extends beyond the walls of the bag at 27 and 28, this being particularly important at 28, in

lgpon a filling tube during the filling of the When paper is sewed, a series of perforat1ons results, which tends to weaken the paper. A reinforcing. strip along the paper tends to overcome this weakening, because it lessens the strain of the thread upon .the paper between the perforations, and because the friction between the reinforcing strip and 4 the paper tends to bind the paper in place and prevent it tearing out along the seam. However, unless the thread is drawn up quite snugly, the friction referred to may not be sufficient to make the paper as strong along the seam as it is elsewhere. When the edges of the reinforcin element are adhered to the walls of the bag etween the line of perforations and the load in the bag, it is evident that the paper cannot be torn along the line of perforations without also tearing the reinforcing element along the same line. The pasted union between two sheets of paper will separate more easily when strain or stress is applied perpendicularly to the plane of the paper than when the line of stress lies in the plane of the paper. 'On' the other hand, a sewed. seam unites paper very securely against-separation in a direction perpendicular to the plane of the paper, but the perfora tions of the sewed 'seam weaken it when stress is applied in a line in the plane of the paper. It will be seen that the seam shown in Fig. 3 combines the advantages of the sewed seam and the adhesive union. In

other words, the walls of the bag will not to the walls of the bag between the seam and the load prevent the wall from tearing out of the seam.

The closure shown in Fig. 7 is similar to that shown in Fig. 3, except that the binding strip 34 is adhered to the walls of the bag separate reinforcing elements 38 and 39 are adhered to thebag across each side of the In the form of closure shown in Fig. 8,

end- A binding strip 40, similar to binding v strip 26, is folded over the end of the bag outside of reinforcing strips 38 and' 39, and a seam 41 is sewed through the binding strip, reinforcing strips'and bag walls. Preferably, binding strip 40 is adhered to reinforcing strips 38 and 39 along lines 42 between the edges of the binding strip and the sewed seam 41.

v The closure shown in Fig. 9 comprls'es reinforcing strips 43 and 44 upon opposite sides of the end of the bag, and a sewed seam 45 passing through the reinforcing strips and the bag'walls. In this form of closure the reinforcing strips are not shown as adhering to the bag walls, but it will be, readily apparent that adhesive may be used with such reinforcing strips asshown in Fig. 9, or that adhesive may be omitted, if desired, where shown in Figs. 3, 7 and 8. Whatever the form of the reinforcement, we prefer to extend it beyond the sides of the bag, especially at the valved corner.

The manner in which the plurality of layers of paper allows the bending of the bag walls is brought out in Figs. 3, 4, 5 and 6. In Fig. 3, the walls are shown in the position which they occupy when the bag is collapsed. In Fig. 4 the walls are shown in the position which they occupy when the bag is filled. It will be readily seen that the various layers of paper do not change their relativepositions at'the seam 33 nor at dotted lines 46, where the bag wall extends inthe same direction in which it extends at the seam. However, the outer layer 48 of the bag wall extends around a shorter radius at bend 49 next to the seam than does the inner layer 50 of the bag wall, while at bend 51 exactly the opposite condition exists, so that each layer moves with respect to the other layer at all points between bends 49 and 51, as will be readily seen by'the positions of dots 52 in'Figs. 3 and 4, respectively. Because the layers are free to move with respect to each other, it will be seen that no greater strain is placed upon the paper at bends 49 and 51 than would result from bending any one of the layers alone.

n Fig. 5, there is shown a diagrammatic illustration of what would occur if the various layers were not relatively movable. As will be readily seen, the inner layers would'be 7 pulled apart adjacent'the seam 53 at bends 54, while the outer layers would be pulled apart at bends 55 at the shoulders of the bag. A similar result occurs when the paper is of one thick layer, as shown in Fig. 6. Here the inner side of the paper cracks open along bends 56 adjacent the seam, while the paper cracks at its outer side along bends 57 at'the shoulders of the bag.

It will be understood, of course, that the relative thickness of the paper is exaggerated in Figs. 3 to 9, inclusive, for purposes of clear illustration.

The end of the 'bag may be folded in to form a valve in the manner shown in Figs. 11 to 15, inclusive. In Fig; 11' the end of the bag is shown opened into substantially rectangular form. vThe corner of the bag may be folded inward and downward along lines 58 diagonally across the corners of the sides of. the bag and along line 59 joining the ends oflines 58.- When this is done, the corner is folded in to form a trough, as shown in Fig. 12. Thereafter, the apex 60 of the gusset fold may be bent inward, the material of the gusset bending along diagonal lines 61 extending from line 60 diagonally upward to the ends of lin'es58. In the meantime, the extension of line 60 at 62,along the material of the valve, is bent downward, the line from the point 63, where line 61 and 60 join, moving straight inward, While the line 64, where lines 62 and 59 join, moves directly downward. In this manner, while line 60 moves horizon tally and line 62 moves downward, the line joining points 63 and 64 changes from a vertical to a horizontal position, as will-be most clearly seen from Fig. 15.

As will clearly appear from Fig. 14, the line between points 63 and 64. which originally constitutes a portion of the apex of the gusset fold bends outward from line 60 to where it is substantially even with the edge of the bag. Line 62, which also originally constitutes a part of the apex of the usset fold extends perpendicularly inward from point 64 into the bag. In this connection, it may be pointed out that the walls of the bag are bent much more sharply at points 63 and 64 than at other fold lines, because at these points the folds themselves are bent. This makes the necessity for pliability, and, therefore, the advantage of multiplelayers, especially important where the valve is formed at the end of the gusset fold. Furthermore, as will readily appear from Fig. 15, the inner layer 50 passes around a much shorter radius at point 64 than does the outer layer 48. and. therefore. the edges of the layers are arranged in stepped relation. This adds somewhat to the flexibility of the edge of the valve.

After the bag has been' emptied, it may vbe reclosed along the same line as before, and with the valve in the same corner, but resewing along the same line may weaken the bag by causing too many perforations along this.

'that successive closures may be made across the bag'at successively greater distances from the end thereof. If a closure such as shown in Fig. 9 is used, the end of the bag may be left in its original position and the closure merely formed a slightly greater distance from the end; but where a binding strip is used across the end of the bag, it is preferable to trim off the bag walls.

' The bag may have its valve refolded in the same manner as before, but if the extra bending of the valve results in obvious weakening of the paper at that point, a similar valve 69 may be folded in at the other side of the bag. Then the end 70 of the bag may be trimmed off as shown in Fig. 18 and the bag reclosed by a reinforced seam 71 similar to the seam 22.

It is sometimes desirableto have the walls of the bag that are to form the valve extend somewhat beyond the adjacent walls, so that, when the valve is folded in, it will extend into the bag some distance and have the upper portion thereof sewed into the seam, as clearly shown in Fig. 1. A convenient way of securing suitable bag lengths, is to cut a continuous tube into lengths in the manner shown in Fig. 10. In that figure there is shown the end of a bag section, such as shown in Fig.

11, except that the gusset folds are collapsed.

The tube from which the length is cut' is shown in dotted lines at 72. This may be cut with an extension 73 at the side of the tube opposite the extension which is folded in to form valve 25. Between these two extensions there will be a small rectangular portion 74 which is discarded, but it is evident that this discarded portion will be less for two bags than it would be for one bag if the tube were cut straight across and then notched out" to form the desired valve extension.

In-Fig. 17 there is shown a somewhat different form of bag, in that no valve is folded in. The tubular portion 75 is constructed in the same way as the bag shown in Fig. 1, but the end closure 76 is shown as being constructed in the manner illustrated in detail in Figure 9. This bag may be used by thrust- .ing a filling tube 77 through the apex 78 of gle-walled bags containing the same without burning their hands. This is an annoying feature in the packing process, and the ma- 1' terial of the bags may be seriously weakened by the heat. These difliculties are mitigated by multiple-walled bags. The air entrapped between the layers of multiple-walled bags acts as insulation and keeps the outer walls cool enough for handling and for the retention of their full strength. By the use of our multiple-walled bags it is possible to package the hot cement or other materials, and to handle these bags barehanded without discomfort.

It is preferred to make the layers of which the bag is composed entirely separate except for the end closures. This allows the free play of one layer with respect to the other and reduces to a minimum the tendency to crack, and furthermore, it allows the removal of one layer. without destroying the entire bag. For example, the bag may be labelled, and after it has been used with one label, it may be desirable to have a different label on the bag during further use; also, the outer tube may become dirty or perhaps torn, and

I it may be desirable tohavea whole clean outer tube for that reason. When it is found desirable to have a new outer tube for any reason, the seams at both ends of the bag may be removed, and the outer tube may be take n OE and a new tube put in its place, thus renewing the bag with the use of only one layer instead of requiring an entirely new bag.

.Or,.if preferred, a new outer tube may be layer, as this gives the added advantage of a new, clean outer layer. It will be seen from the above that a multi-walled bag, constructed of nested tubes attached to each other only at their ends, may be used indefinitely, and repaired by renewing only such of the Walls as are not suitable for further use.

When one layer has a comparatively small hole therein, While the remainder of the layer contains sufiicient strength to ,render its further use desirable, such layer may be readily patched by inserting an adhesive patch-between the layers of paper when the end of the bag is opened. In such cases we prefer to use a patch having adhesive upon only one side thereof, so that the relative movement of the layers is not restricted by the patch.

It is sometimes desirable, when both ends of the tube are opened to renew a layer, or for other reasons, to form the valve in one of the corners at the opposite end from the original valve. If desired, the four corners of the bag may be used in succession for this purpose.

In the preferred form of bag, the longitudinal seam of each tube is formed by adhering together the edges of a sheet, so that there are as many adhered long seams as there are layers of paper. Such a long seam is less likely to give way than a corresponding sea-in of a single paper wall of thickness equal to the multiple walls. This is because an adhesive unites only theouter skins of the layers of paper, and Where thick paper is used the seam sometimes parts as a result of the tearing loose of this outer layer or skin from the body of the paper. With thinner paper this splitting of the paper or tearing loose of the outer skin is less likely to occur. The seam of a multiple walled bag is formed by the adhesion of a plurality of pairs of such outer skins, and therefore the strength of the seam is multiplied. In practice, the paper usually used for the multiple walls is thin enough so that the full strength of the paper is available at the seam, and the lapped seams actually form reinforcing strips.

. The number, as well as the quality of layers whichare desirable depends upon numerous factors, and therefore no single description can set forth the best construction for all purposes. However, certain general principles may be stated, and at least one specific instance will be given.

Ordinarily the desirable thickness of a single layer depends upon the nature a of the paper and the thickness which is strongest in proportion to its weight for the particular paper used. Bymaking the wall of a'plurality of layers and using as many layers as necessary, it is possible to choose that thickness of the paper which gives greatest strength in proportion to the weight and use as many thicknesses as necessary, in this way obtaining the greatest possible strength for the amount of paper used. As the difliculty in making the bags is somewhat increased by increasing the number of layers used, it is bet ter to have the individual layers thicker, rather than thinner, than the layers which give maximum strength per Weight.

We will not attempt to give the most efficient thickness for various kinds of papers, but we have found it to be a general rule that with any particular quality of paper there is a thickness which gives the maximum strength in proportion to weight, which thickness may be readily ascertained for the particular paper-used, WVe have used sulphite wood pulp paper extensively for forming multi-walled cement bags, but this kind of paper would be so stiff as to be entirely unsuitable if any attempt were made to use it for cement bags having but a single wall. The strength of.the bag is increased by subdividing the paper into layers until a certain point is reached, but further subdivision weakens the paper instead of strengthens it.

customarily used for making bags, For best results in making bags for heavy service out paper,

of ordina wood ulp pa er, the paper should be not lighihr than thirty pound nor heavier than fifty pound paper. About thirty-five pound paper is probably the strongest in proportion to the amount of paper, but for reasons mentioned above, a somewhat heavier paper may be the most economical, and in'practice we have extensively used five layers of forty pound paper, and four layers of forty pound paper with anouter layer of fifty pound paper.

While we have specifically described a valved bag suitable for packaging cement, it will be understood that other kinds of materials may be packed in our bags, that some of the features described and claimed may be advantageously used in connection with other types of bags, and that various modifications may be made -without departing from the spirit of our invention. As indicted above, the nature of the various layers of paper may be varied somewhat in accordance with the particular use intended.

What we claim is 1. A paper bag for heavy service, comprising nested tubes, the tubes being attached to each other only by sewed seams at the ends. 2. A paper bag for heavy service, formed of a nested series of tubes, the plies of which are relatively movable at all places which are the fold lines of the gusset folds, thewalls of especially subjected to bending, having a reinforcing element applied to a side of the bag across one end and the end of the bag being closed by removable means passing through the reinforcing element and the bag wall.

3. A paper bag for heavy service, formed of a nested series of gusset-folded tubes, the several tubes being relatively movable along an end of the bag being collapsed along a straight line and the several lies of the walls being united and; the end 0 the bag closed by a seam sewed along said line.

4. A pa er bag for heavy. service, formed of a neste series of tubes, the plies of which I are relatively movable atall places which are especially subjected to bending, and having walls, the reinforcing element being adhered to the bag walls on the side of said removable means away from the end of the bag and beingfree from adhesive along the line of'the removable means,

6. A paper bag having reinforcing means adhered. to the wall of the bag along a line adjacent an end of the bag and a seam sewed through the bag walls and the reinforcing means along a'line, free from adhesive, between said line of adhesive and the end of the bag.

7. A paper-bag having an end collapsed and reinforcing means extending across the two faces'of sald end, portions of said means being adhered and sewed to said two faces, ilzhe adhesive and sewing being along separate mes.

8. A gusset folded paper bag having an end collapsed and reinforcing fneans extending across the said end and beyond the sides thereof, portions of said means being adhered and sewed'to the bag wall and adhered and sewed to each other beyond the sides of the bag, the adhesive and sewing being along separate lines.

9. A bag having a valve formed therein by tucking in its wall at one corner thereof and having reinforcing means extending across its end and beyond the valved corner,

portions of said means being adhered and sewed to the bag walls and to each other beyond said valved corner.

10. A bag having a valve formed from a plurality of layers of paper, the several layers being relatively movable where they form the edge of the valve.

11. A multi-walled paper bag having a portion of its walls folded in to form a valve, the several layers of the walls being relatively movable where they form the edge of thevalve.

12. 'A- bag comprising a multi-walled bellows-folded paper tube having its end closed by securing together the ends of its flat sides and avalve at the apex of a fold at its end ing into the bag farther than the bellows-fold when the bag is collapsed.

14. A multi-walled bellows-folded paper bag having the extreme upper end of the bellows-fold folded down into the bag to form a filling valve, the bellows-fold immediately below said downward folded portion being bent outward to form a lower wall for the valve and a guide for, a feed tube, a reinforcing strip folded over the end of the bag and extending beyond the walls of the bag at said valve, and the Valve end of the bag being closed by a sewed seam.

"In testimony whereof we have hereuntosigned our names to this specification. ADELMER M. BATES.

JOHN EVANS CORNELL

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