US2142656A - Bag or the like of composite materials - Google Patents

Description

Jan. 3, 1939. I w, w, ROWE 2,142,656

BAG OR THE LIKE OF COMPOSITE MATERIALS Filed Feb. 12, 1951 INVENT (MzM/aflm awe ATTORNEY-S.

7 formation of rolls of connected fabric.

Patented Jan. 3, 1939 TED BAG 0R THE MIKE 0F (COMPUSK'ILE MATERHAJLS Application February 12, 1931, Serial No. 515,359

1 Claim.

Bags for the shipment of relatively heavy materials of powdered nature, such for example as fertilizer, have heretofore been made of a composite fabric comprising a layer of burlap and a layer of creped paper adhesively united together. Such a fabric and such a bag are exemplary of the class to which my invention appertains, but they are not limiting; and my invention may be employed in bags of other materials, as will be apparent to one skilled in the art upon reading this specification. My invention is also applicable to the manufacture of other structures than bags, which structures are of a size or configuration necessitating the use of seams. Exemplary of such structures are sheets, tarpaulins, covers, fitted or not, for objects to be protected, and the I shall, however, describe my invention in an exemplary embodiment as related to a bag of the character described and more particularly, a bag made of a composite fabric of burlap and creped paper, in which the paper is joined to the burlap by means of an asphaltic substance as an adhesive. Preferably the creped paper. will have been creped through the employment of the positive adhesive action of asphalt or the like as covered by my re-issue patent, No. 17,633, dated April 1, 1930, and the adhesive used in creping the paper will be the adhesive used to join the paper to the burlap.

Bags have regularly been made of this fabric or other relatively similar fabric by cutting a blank, and folding the blank over upon itself with the paper side innermost. The edge opposite the fold and one of the adjacent sides are then sewn together and the bag is complete. A number of special types of seam have been suggest'ed with which my invention is not concerned.

There is usually some difficulty in sewing a fabric which contains asphalt; there is also, as against lateral strains, a tendency for the thread of the stitching to pull the strands of the burlap to the extent of opening up the needle holes and permitting the contents of the bag to sift through these holes in some instances. When a bag is made as just described, and is then filled, the pull upon the stitching in a seam is not in the same plane as the stitching itself, and where such a strain occurs there is not only a greater tendency for the needle holes to open up, but the effective strength of the seam has been shown to be diminished. Attempts have been made to produce tubular bag stock by folding a strip of fabric over on itself and lapping the edges to form a tube or cylinder and then making one or more lines of stitching in the overlapped portion, lengthwise of the tube. Such a process involves special machinery and is more expensive; but it makes a seam which is relatively stronger than the seams which I have first described because mary object of my invention, in structures and in bags made of the materials of the class of my exemplary embodiment, is the production of an adhesively secured seam. By the process and in the article which I shall now describe, I have succeeded in making seams which are stronger than straight overlapped seams with three lines of parallel stitching. Other objects of my invention are apparent from the following specifications and references now made to the accompanying drawing, wherein:

Figure l is a perspective view of tubular stock for bags embodying my invention.

Figure 2 is a sectional view of a seam embodying an interfolded construction.

Figure 3 is a perspective view of a filled bag.

The sectional view of the seam is somewhat conventional in the showing of the several materials and layers of adhesive substance, and is exaggerated in thickness, for the sake of clarity.

After considerable experimentation, I have discovered that the production of adhesively secured seams in materials of this class involves certain commercially essential features. I have discovered that it is essential to paste textile material to textile material-4n the exemplary embodiment, burlap to burlap-in order to secure not only adequate strength, but adequate resistance to external conditions in the uses to which the bags will be put. To cement paper to paper or paper to burlap will not of itself give adequate strength. The paper is, in the first place, weaker as respects disruptive strains, and in the second place, in such a cemented construction the strains incidentto use Will tend to separate the plies of material. Where paper is cemented to paper, the paper layer alone must bear these strains, and where paper is cemented to burlap, the asphaltic layer within the composite material becomes an integral part of the seam, and the strains from burlap to burlap must pass through this asphaltic layer. Under conditions of extreme cold the asphalt may become brittle, while under conditions of external heat, or where the bags are filled with hot materials the asphalt may soften. Again, if paper is cemented to paper in a construction such as the first hereinabove described, the strain in the seamwill not be in the plane of the adhesively joined materials. Secondly, it is necessary that some adhesive other than an asphalt or other bitumen be used inasmuch as bitumen is subject to change of characteristics by temperature.

The adhesive chosen will, in addition, of course, nave adequate strength, and for use in my invention it will be of such a character as will bond firmly with the fibers of the textile material employed. Finally, it should preferably be such an adhesive as will not tend to commingle with the bitumen or to have its strength impaired thereby, since as applied it will, in certain forms of the invention, come into contact with the bitumen through the strands of the burlap. It is convenient to have an adhesive .which can be applied cold, and which has as its solvent a liquid which is not a solvent for bitumen.

Among the adhesives which I may use having the required characteristics, I have found rubber latex cement to be entirely suitable. Rubber latex cem'ent as used by me, is usually the natural product of the rubber-bearing growths concentrated in some instances by the removal of a portion of its water content, and in some instances containing some substance, such as ammonia, which will tend to preserve it and to increase the stability of its emulsified character. The cement may, if desired, have other materials such as vulcanizing substances, or even mere adulterants, added. Rubber latex cements are readily procurable, and are convenient to use, since they ordinarily require only a simple air drying and may be employed without the use of heat.

I designates the burlap; 2 the crepe paper; 3 the layer of bituminous or other adhesive therebetween, and 4 the layer of different adhesive,

preferably non-heat plastic and non-bituminous,

used in securing textile material to textile material. That portion of the meeting fabric which has a part cemented down above and part of the other portion, I have referred to as the upper layer, said other portion being correspondingly the lower layer.

Referring to the seam shown in Figure 2, the paper is left free from one edge of the burlap in the upper layer and cemented clear out to the edge of the burlap in the lower layer, as shown. The free burlap forms an attachment fabric flap la, andis cemented down upon the burlap of the lower layer by an adhesive layer 4 of rubber latex or the like. The depending portion 21), which in this instance is of paper to form a paper flap, may be allowed to lie free beneath the seam. If the paper has been creped through the use of a heat plastic adhesive, and a layer of this adhesive is left upon its surface, the paper may be self cementing beneath the seam under the pressure of the contents placed within the bag, or a separate adhesive may be applied and the seam cemented down. In this type of seam, the edge portion of the lower layer is essentially interweaved or sandwiched between separated portions of the upper layer as will be quite clear. In making a blank with an edge portion comprising separated plies, it may be sufiicient merely to refrain from pressing the paper against the burlap in the construction of the composite material, or a strip of paper or the like may be run in at the edge between the burlap and the paper, thereby preventing the sticking of the two, particularly where the paper has been creped by means of an adhesive substance. Where the paper has been pre-creped and afterward treated with adhesive, it will be sufficient to omit to place adhesive on the paper at one side of the blank, over the distance through which it is desired to leave the plies free of each other.

It will be understood that the seam which I have just described, and other modifications falling within the scope of my invention may be applied to side scams, or bottom or top seams, but are more generally applicable to side seamsbecause of the relatively greater difliculty of securing at the cut edges' of the tube, the particular character of overlapped relationship which I have described. The bags are ordinarily made in flat form and it will be understood that the location of the side seams may be central, at the sides or at or near the edges of the blank, and that the latter construction will be preferable where printing-is to be done upon both sides of the bag.

I have shown in Figure 3 a completed bag l6, having a side seam I! and a bottom seam I8. The bag is shown as closed by tying as at H, but other methods of closure are equally applicable. Bags .of my type may be made with slack tops if desired, or with other structures designed to solve specific closing problems.

In making my bags in continuous production, it is sometimes preferable, instead of working with individual blanks, to form the composite fabric into the tube 20, of Figure 1, where the seam is indicated at 2|. Dotted lines show lines of outing in severing the tube of Figure 1 into individual bag pieces.

As I have hereinabove indicated, my invention is not restricted to composite fabrics of burlap and creped paper, but is applicable to a large number of other fabrics having a textile layer which is designed to bear the strain. It is also applicable to composite materials having strainbearing layers which are of textile character in the sense that they comprise strands, cords, filaments and the like, of a'wide variety of forms but which are no necessarily woven. Braided structures do not fall without the scope of my invention nor do structures in which paper or other proofing or non-sifting plies are joined to or reinforced by fibrous structures of other than woven character, provided these structures are sufilciently cohesive to permit their adhesive juncture to similar plies in order to provide the necessary strength for the bag. In the ensuing claims, I desire the word textile to be interpreted in the light of this paragraph.

Certain of the constructions described above make it possible to produce pasted seam bags with the selvage edge of the textile material either at the side or at the top of the bag. It is desirable in some instances, to have the selvage of burlap at the top of the bag, and it is also desirable to be able to fold the bag blank either way in order to get certain sizes of bags out of standard widths of textile material.

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

A seam for composite materials comprising textiles to which are adhered other materials, comprising adjacent edge areas of said materials, one of said edge areashaving a separated relationship between its textile layer and its other material, the non-separated composite material of the other edge area being introduced therebetween, and latex between the textile edge portions of the two areas where they face one another.

WILLIAM WALLACE ROWE.

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