US2071362A - Bag and container for heavy duty - Google Patents

Description

W. W. ROWE Feb. 23, 1937.

BAG AND CONTAINER FOR HEAVY DUTY Filedy April 4, 1935 IIIIIIIIIIIIIIIIIIL fav:

- INVENTOR.

ATTORNEY.

Patented Feb. 23, 1937 UNITED STATES PATENT GFFICE William Wallace Rowe, Cincinnati, Ohio, assigner.

to The Paper Service Company, Lockland, Ohio,

a. corporation of Ohio Application April 4, 1933, Serial No. 664,377

16 Claims.

My invention relates to bags or other flexible containers of novel characteristics and materials. By heavy duty I refer to containers capable of carrying 50 to 100 pounds or more of contents; but it will be understood that the size and Weight carrying capacity of my containers do not constitute limitations upon my invention. Heretofore heavy duty bags have been made of multiple walls of plain paper or of textile material, such as burlap, sometimes with an inner liner, or of composite fabrics comprising textile material cemented to creped paper. In the multi-Wall paper bag, the object has been to add together enough plies of paper so that the ultimate strength of the sum of these plies will be greater than the shocks to which it is expected the bag will be subjected. The plies were left free of each other, because it would be impracticable to cement them together in a solid fabric. Such a solidly cemented fabric would be inflexible and would crack upon bending. Again, in bags of textile material or composite materials, it has been the endeavor to provide a bag wall of sufficient ultimate strength to withstand the expected shocks.

It is an object of my invention to provide a more serviceable container, and more particularly a container adapted to withstand individual or successive shocks in a superior way. It is an object of my invention to provide a container which can withstand a series of shocks greater than the ultimate strength of the materials of which the container is made. It is a further object to provide a container in which resistance to shocks and strains is a function of the elasticity of the materials of the container, rather than of their ultimate tensile strength, i. e. a container in which strength is secured through stretchability. Still another object of my invention is the provision of containers which have greater serviceability though made of cheaper materials. Still another object of my invention is the provision of containers of paper materials which nevertheless can withstand a greater succession of shocks than containers heretofore made of multi-wall paper, or of textile materials as the primary strengthening element, the fabric of which is of the same or even greater weight per square unit of area than the webs in my container. Still another object of my invention is the solution of the problems involved in seam formation in containers, and more particularly the elimination of desiderata heretofore considered essential in the formation of cemented seams in containers.

Another object of my invention is the provision of a container made primarily of paper in a single or in a plurality of plies, and in which, if a l plurality of plies are employed, the plies may be cemented together with attendant advantage, and without loss of adequate flexibility and stretchability.

These and other objects of my invention, which will be set forth hereinafter or will be apparent to one skilled in the art upon reading these specifications, I accomplish by that certain construction and arrangement of parts of `which I shall now describe certain exemplary embodiments, reference being had to the drawing, wherein:

` Figure 1 is a plan view of one bag which may be made in accordance with my invention, with the original bag blank indicated in dotted lines.

Figure 2 is a somewhat exaggerated and diagrammatic section of the bag of Figure 1, taken along the lines 2 2.

Figure 3 is a plan view of another exemplary 20 form of bag.

Figure 4 is a sectional view of the bag of Figure 3, again exaggerated and semi-diagrammatic, taken along the lines 3--3 in Figure 3.

Figure 5 illustrates the effect of repeated end 25 drops upon a bag of my invention.

Fig. 6 is a sectional view, somewhat diagrammatic in form, of the exemplary fabric which I may employ in carrying out my invention.

Briefly in the practice of my invention I form i a bag or container of a material which is simultaneously expansible in all directions, so that the strains set up by rough handling, as in the dropping of the bag when loaded, will be absorbed in the resultant expansion. I believe this to be a complete novelty in the construction of containers and bags of the class to which my invention is addressed. I have found that in the practice of my invention the ultimate bursting strength of the materials, while high, is nevertheless not a factor in their serviceability unless and until the whole resident expansibility of the strained area throughout the bag is destroyed; and the tearing strength of the materials, while also high, is not a factor in their serviceability until the bag wall has been punctured.

In cloth bags, or bags which are combinations of cloth and paper, while there is a possible distortion along the bias, this distortion or stretchability occurs at the expense of contraction else- Where, and there is substantially no stretchability transversely or longitudinally of the fabric. Thus, substantially the entire strain of an end drop on a filled bag is applied against the ultimate bursting strength of the structure. In bags having seams held by sewing alone, there are factors which tend to cause the rupture to occur in the seam. Seams can be made which are stronger than the materials themselves; but then the entire stress is applied against the ultimate bursting strength of the fabric.

In a multiple wall paper bag, since there is no stretchability in the several plies, the stresses are immediately effective against the ultimate strength of the material which, therefore, in the aggregate has to be very heavy.

In my novel structure the stresses so produced are relieved by an expansion of the fabric itself. The fabric is preferably one in which expansion is resisted within the ultimate strength limits, and it may be one in which there is a strong resilience, or tendency of the material to return to its original unexpanded form. It will be obvious, however, when the character of stresses to which bags are subjected is considered, that the stretchability to be serviceable to my end, must be a universal stretchability and not merely a unilateral stretchability, or a stretchability limited to a few specific directions. But it will also be apparent that the stretchability to which I refer is effective against localized as well as general stresses, for which reason my structures are very resistant to puncturing. Not only this, but so long as there is suflicient universal stretchability to absorb the stresses aforesaid the seam is likewise protected from strain, and there is no necessity for a seam construction which itself is elastic. Thus, while my invention is not limited as to seam construction, I may employ a very much simpler seam than has heretofore been found necessary.

In a co-pending application Serial No. 668,106, filed April 26, 1933, I have set forth a fabric comprising a plurality of plies of universally stretchable creped paper. The plies themselves are preferably made in accordance with the teachings of the co-pending application of William C. Kemp, Serial No. 558,884, filed Aug. 24, 1931, which teaches a process of creping paper and a product which is the result of that process, and which comprises paper having a plurality of crossing sets of diagonally disposed creping crinkles. The paper is a true creped paper as dstinguished from a corrugated paper or a paper having such large or irregular rugosities as would prevent a fairly continuous bond to another web in making up a plural ply fabric. My invention, however, is not limited to this particular type of universally stretchable fabric.

Two or more layers of this universally stretchable paper are joined together by a suitable adhesive to make a plural ply fabric. The adhesive used for the purpose may be, if desired, the thermoplastic adhesive employed in the creping operation, such, for example, as asphalt, or it may be an additional adhesive, or, if no thermoplastic adhesive substance has been used in the creping operation, it may be a superadded adhesive substance. I have set forth in my copending application referred to, a plural ply fabric of this character joined by means of asphalt, and also a modification in which stretchability is additionally resisted by certain types of reinforcements in the adhesive joining the plies, such as heterogeneously arranged and relatively short fibers.

This particular fabric which is exemplary only of those I may use, is illustrated in Fig. 6, where three layers of double diagonally creped paper I8, I9, and 20, are shown joined together by layers of asphaltic substance 2l and 22.

In another co-pending application Serial No. 668,105, filed April 26, 1933, I have set forth a plural ply fabric in which a resilient and elastic coating substance is an integral part, Whether employed as the means for building up the plural ply fabric, or not. Any of these materials may be employed by me in my present invention which, as to the fabric, is not limited otherwise than to a single ply of universally stretchable paper or like material, or to a plurality of layers of universally stretchable material.

I have shown in Figure 1 a blank l which, when folded and joined by a center seam 3, will form the bag body 5. The structure shown is exemplary merely of a type of bag which may be made in accordance with my invention, and does not otherwise constitute a limitation. A bottom seam 6 may be formed in this particular structure by turning over an integral body flap 1. Likewise, I have shown a top sealing flap 8 also having integral portions joining it to the opposite body wall and indicated at 9 and I0. After lling this bag, the top flap may be turned over and cemented in place or otherwise fastened as desired. A sealing method of particular advantage in bags of this character is Set forth in my co-pending application Serial No. 647,000, filed Dec. 13, 1932, and involves the coating of parts to be lapped and joined with an uncured rubbery substance, and protecting this substance from influences which would tend to destroy its adhesiveness to bodies of a similar substance. When the protective material has been removed, the parts may merely be lapped and pressed together, whereupon the instant adhesion produces a strong bond.

In Figure 2 I have indicated a cross section of the body of the bag of Figure 1 to show a satisfactory character of seam construction 3, which comprises merely the lapping of the parts and the joining of them by means of the adhesive Il. Hitherto, in heavy duty bags made of composite materials it has been thought impracticable merely to lap and join the edges of. the body fabric. Thus, in composite materials of textile and paper, it has been thought necessary to provide a seam construction in which textile material may be cemented directly to textile material by means of rubber latex or the like. A seam construction in which the paper is involved as an integral element has been thought impracticable, because the paper itself is not the main strength giving element of the bag, and also because in the usual forms of construction the paper is joined to the burlap by an asphaltic layer subject to softening and slippage under the influence of temperature. Likewise, in heavy bags of uncreped duplex papers, it has been thought necessary to provide a structure for seam formation in which the several plies are non-coterrninous, and to cement the outer ply directly to the outer ply, and preferably also the inner ply directly to the inner ply by means of some adhesive substance other than the bitumen by which the plies are combined to make the duplex paper.

In the multi-wall bag, on the other hand, in which the several plies of paper are free of each other, it is obvious that a single cemented seam intended to be effective for all plies, would be inoperative unless some attempt were made to join all of the plies, as by cementing them together, at least over the area of seam formation. Such an attempt would be uneconornical. Even if the plies were so joined, however, any slippage of the plies would result in the strain being thrown against the outer ply or plies, and a great reduction in seam strength. Moreover, the joining of the several plies would build up a stiff, thick material subject to cracking when bent. All of these disadvantages arise through the lack of stretchability in the paper.

In the bag of my invention, plain lapped and cemented seams or butted joints with overlying cemented strips and the like are found perfectly satisfactory from the standpoint of strength and serviceability, and they also, of course, greatly simplify the construction of seams. The reasons for the efficacy of such simple seams in my construction I believe to reside primarily in the universal stretchability of the bag fabric itself. So long as there is any resident stretchability in the walls of the bag, the seam is protected. Likewise, due to the universal stretchability of the body walls of my bag where they are formed of plural ply materials, there is no tendency for the walls to slip in the seam construction, whereby inordinate strain might be put on the outer ply or plies. In cemented constructions of the type refered to, the material in the lapped portions is relatively less stretchable than the material elsewhere. Consequently, the body walls of the bag Will stretch before a slippage will occur in the seam. Hence, since the layers in the seam do not slip, the seam construction retains its unimpaired strength. In this way I have succeeded in making adequate lapped seams in plural ply paper fabrics without the necessity of special constructions.

It will be understood that ordinary machinemade paper has a preponderant grain direction which makes its tensile strength greater in one direction than in a direction at right angles thereto. The most severe stresses encountered by a bag under conditions of use are bursting stresses transverse to the length of the bag. This is because a bag, if dropped on end, receives a greater effective stress by reason of the greater height or head of its contents than if the same bag were dropped on its side or on its edge. As an added factor of safety in my bags, I prefer to construct them in such a way thatthe grain of the paper is transverse to the length of. the bag, whereby the ultimate strength of the bag in the direction of greatest stress is increased, particularly when the bag is considerably greater in length than in width.

Since it is characteristic of my structure that the ultimate strength of the paper is not a factor so long as the resident stretchability is not wholly removed; it follows that the effective resident stretchability of the fabric of my bag, l. e. the percentage of stretch in the paper is the factor of greatest importance in determining the serviceability of the bag. The percentage of effective stretchability in the ydirection of greatest strain is therefore far more important than the ultimate strength of the paper in said direction. Universally stretchable paper materials may have different percentages of stretchability in different directions or may be equally stretchable in all directions. Consequently while my invention is not limited in this respect, I prefer to have the percentage of stretchability the greatest in the direction of greatest strain which, as hereinabove pointed out, is transverse to the length of the bag. With universally stretchable paper having a substantial degree of stretchability, very satisfactory bags may be made by providing a fabric in which the stretchability is equal in every direction; but if the fabric employed has markedly superior stretchability in one direction, I prefer to conof relatively light universally stretchable paper,v

which will more successfully carry the same Weight of contents, and which will withstand a much higher single drop or a greater succession of drops from a given height than bags of greater weight comprising burlap and paper or made of plural plies of uncreped paper, and this in spite of the fact that the ultimate tearing strengthl and the ultimate bursting strength of my material, when all of the stretch has been removed therefrom, may be very much less than that of the burlap alone or the plural plies of uncreped paper.

My bag will withstand substantially any stress the effect of which is insufficient to remove all of the stretch in the bag walls in the strained areas. For this reason the walls of my bag may be bent sharply and in spite of the tendency to remove some of the stretchability, the walls will be weakened less than would be the case with uncreped paper or single creped paper bent along transverse to the direction of the creping. Even this however, may be overcome by reinforcing the side edges of the bag by the use of additional strips of material or otherwise; and since the resident stretchability of the remainder of the bag walls protects these reinforcing con,- structions as well as the seams, no provision for stretchability or elasticity, While desirable, is essential in such reinforcements. I have also overcome the difllculty in the bag of Figure 3. by forming seam constructions at the side edges of the bag. The walls of the bag of Figure 3, shown in section in Figure 4, are indicated at I2 and I3. At the side edges these Walls are coterminous, and strips of material I4 and I5 are bound thereabout. 'I'he material in these strips may be, if desired, the same as that of the bag walls, or they may be of other or ultimately stronger materials, such as textile fabrics or combinations of textile fabrics and paper. In any event, however, the thickness of the edges of the body walls of the bag protects the material of the seam from undue compression. It will be noted that the bag of Figure 3 is square in shape. I have found that such a bag form evens up the stresses and tends to give a structure of even greater serviceability.

I have hereinabove indicated that my bag will preferably be formed of plies of universally stretchable material cemented together with a substance which tends to resist the removal of stretch within the limits of the ultimate strength of the plies. I have likewise indicated that the bag may be formed of one or a plurality of plies of universally stretchable material combined with or having in association a material which tends resilientlv to resist the removal of stretch and to return the fabric more or less to its original unstretched condition after the alleviation of the stress. Materials having an external coating of rubbery material may likewise be used to advantage ln my present invention, both because of the increased imperviousn'ess of such fabrics,

and also because the external covering of rubbery material gives them a so-called non-skid quality facilitating the stacking of the bags.

Assuming that the plies are joined by asphalt or the like which merely resists the removal of stretch, the result of repeated strains upon a bag of my invention is illustrated in Figure 5. This condition is brought about, for example, after the b ag has been loadedl with say 100 pounds of material, and has been repeatedly dropped on its end from a height of say two feet. After manyrepeated drops, the condition of my bag may be as shown, with the lower portions of the side walls ballooned out as indicated at IB and I1. This represents. oi course, an exaggerated condition, and one seldom encountered in the actual commercial use of the bag. Yet the bag is still intact, and will be until subjected to sufficient stress to remove all of the resident stretch and to subject the plies in their unstretchable condition to a force greater than their ultimate bursting strength. In the bag of my invention, I have also found that as the stretch is removed from the bag walls, the so-called spill room is increased, which is a factor tending to alleviate further stresses. If a bag of textile material or of combinations of textile and paper is filled full and closed so as to cause the walls to bear tightly against the contents, a very much smaller stress will be required to burst the bag. 'I'his is because the entire stress is immediately applied against the ultimate strength of the material. Bags filled less full can withstand a pro- -portionately greater amount of stress, because of the so-called spill room. In my bag. spill room increases With stress, either temporarily or permanently, and the effective serviceability of the bag is thereby greatly increased. Thus, the bags of my invention in filling may be stuifed tightly, and will be found fully serviceable for reasons hereinabove given. Indeed, there is an advantage in stufling the bags full in the filling step, since when the walls are completely supported by the contents, puncturing occurs less readily.

It will be evident that my invention is not limited to any particular form of bag'or seam construction, nor to the specific fabric herein disclosed, excepting where such features are speciiically set forth in the appended claims; and that modiiications may be made in my invention without departing from the spirit thereof.

Having thus described my invention, what I 'claim as new and desire to secure by Letters said layers being in intimate contact with eachv other.

2. Aiplurai ply, flemme bag or like container, all elements of which are capable of giving. or stretching bodily in opposite directions along the axes of said container, said container comprising a plurality of layers of universally stretchable substance, at least one layer of which is a layer characterized by universal stretchability derived from gatherings therein, and at least one layer of which perates to retard the distention of said like container,

gatherings in said ilrst mentioned layer, all of said layers being in intimate contact with each other, at least two of said layers being in adhesive union with each other.

3. A plural ply, iiexible bag or like container, all plies of which consist of elements characterized by universal stretchability, and which comprises a plurality of layers of paper in which the universal stretchability is derived from gatherings, all plies of said con'tainer being in intimate contact with each other.

4. A plural ply, flexible bag or like container, all plies of which consist of elements characterized by universal stretchability, and which comprises a plurality of layers of paper in which the universal stretchability is derived from gatherings, all plies of said container being in intimate contact With each other, and certain of said plies at least being joined by means of a stretchable adhesive.

5. An expansible container consisting of elements all of which are capable of giving or stretching bodily in opposite directions along the axes of said container, and comprising a plurality of layers of gathered material in intimate contact with each other.

ments all of which are capable of giving or stretching bodily in opposite directions along the axes of said container, and comprising a plurality of layers of gathered material joined by means of a stretchable adhesive.

'7. A plural ply, exible bag or like container, all elements of which are capable of giving or stretching bodily in yopposite directions along the axes of said container, said container comprising a plurality of layers of universally stretchable substance, a plurality of said layers characterized by universal stretchability derived from gatherings therein, and at least one universally stretchable layer of which operates to retard the distention of said gatherings in one of said ilrst mentioned layers, and is in adhesive union therewith, all of said layers being in intimate contact with each other.

8. A plural ply, ilexible bag, or like container, all elements of which are capable of giving or stretching in both opposite directions along the axes of said container, said container comprising a plurality of layers of universally stretchable substance, a plurality of the layers characterized by universal stretchability derived from gatherings therein, and at least one universally stretchable layer of which operates to retard the distention of the gatherings in one of said rst mentioned layers, and all of said universally expansible layers being joined by a stretchable adhesive.

9. A plural ply, exible bag or like container, all elements of which are capable of giving or stretching in both opposite directions along the axes of said container, said container comprising a plurality of layers of universally stretchable substance, at least one layer of which is a layer characterized by universal stretchability derived from gatherings therein, and at least one layer of which operates to retard the distention of said gatherings in said first mentioned layer, said last mentioned layer comprising heterogeneously arranged and relatively short bres held in a matrix of stretchable coating substance.

l0. An expansible bag or like container, all elements of which are capable of giving or stretching in both opposite directions along the axes of said container, comprising a plurality of layers of paper creped by means ol a thermoplastic adhesive and characterized by crossing sets of creping crinkles.

11. A bag or like' container, all elements of which are capable of giving or stretching in both opposite directions along the axes of said container, comprising a plurality of plies of -universally stretchable paper joined together by means of a stretchable adhesive, said container having seams characterized by lapping and adhesive juncture of the body materials as such.

12. An expansible bag or like container, all elements of which are capable of giving or stretching in both opposite directions along the axes of said container, comprising walls of universally stretchable paper joined together by means oi' a stretch- `able adhesive, said walls being substantially co- .terminous at an edge of said bag and lapped in the marginal portion or a binding strip.

13. A plural ply, flexible bag or like container, all elements of which are capable of giving or stretching in both opposite directions along the 'axes'of said container, said container comprising a plurality oi' layers of universally stretchable substance, at least one layer of which is a layer characterized by universal stretchability derived from gatherings therein, and at least one layer oi' which operates to retard the distention o! said gatherings in said rst mentioned layer, all of said layers being in adhesive union, said container having seams in which an edge portion is bodily lapped by and adhesively joined to another seam forming element.

14. An expansible container, all elements of which are capable of giving or stretching in both opposite directions along the axes of said container, comprising a plurality of layers of material in adhesive union, at least one oi' which layers derives its expansibility from gatherings therein.

15. An expansible container, all elements of which are capable of giving or stretching bodily in both opposite directions along the axes o1' said container, comprising a plurality of layers of material in intimate contact with each other, at

least one oi.' which layers derives its expansibility from gatherings therein. y

16. An expansible bag or like container, all elements of which are capable oi' giving or stretching in both opposite directions along the axes of said container, comprising a plurality of layers oi' material in adhesive union, at least one of which layers derives its expansibility from gatherings therein, and at least one of which layers operates to retard the expansibility of another layer.

WILLIAM WALLACE ROWE.

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