US1944613A - Construction of bags - Google Patents

Description

Jan. 23, 1934. v w. w. ROWE CONSTRUCTION OF BAGS Filed Feb. 12, 1931 low A TTORNEYS.

I 35 has.

50 cated, and the bag, as such, is complete.

Patented Jan. 23, 1934 UNITED STATES PATENT OFFICE CONSTRUCTION OF BAGS Application February 12, 1931. Serial No. 515,358

9 Claims.

'My invention relates to bags or other structures designed to be non-sifting and relatively impervious; and its chief object is the provision of a top sealing or closure structure which has these characteristics, as well as a process of making the same. My invention further relates to bags of a fabric, structure, or materials comprising a plurality of layers. A type of bag in commercial use for the shipment of powdered substances such ,10 as fertilizer, is made of a composite fabric comprising burlap to which is cemented creped paper, the burlap contributing to the strength of the bag and the creped paper making the fabric impervious and non-sifting. I shall describe my inill! vention in connection with a bag made of these materials, it being understood that the embodiment is exemplary, and that my invention is not limited to bags made of such materials nor to the specific construction of bag particularly described.

The general and specific objects of my invention will be sufficiently clear from the following description, and reference is now made to the drawing which forms a part hereof.

In the drawing: 7

Figure 1 is a semi-diagrammatic view of apparatus used in forming the material of which my bags are made.

Figure 2 is a sectional view of a blank.

Figure 3 shows a blank folded to make a bag.

Figure 4 is a sectional view of a bag open to receive the material it is designed to hold.

Figure 5 is a sectional view of a filled bag with the paper flaps folded over.

Figure 6 is a sectional view of a filled and closed Figure 7 is an enlarged sectional view of the top edge portions of the blank.

Figure 8 is a sectional view of construction of blank.

I have indicated at 1, a blank of material comprising creped paper cemented to burlap. A

an alternative common way of making bags of such a blank is to fold it over on itself as shown in Fig. 3 with p the creped paper within. The side edges are 5 folded over on themselves as at 2, and the bottom edges are also folded over on themselves as at 3,

making a seam-forming portion comprising four thicknesses of material. A line of stitching 4 is produced in the seam-forming portions as indi- This is but one form of construction commonly employed in bags, and other constructions, many of them less simple, are equally suitable and in some cases preferable.

My invention is concerned primarily with a structure at the top or closure of the bag, and a method of making it, which will render the closure satisfactory from the non-sifting standpoint, when the bag is hand-sewn in closing. It will be understood that the top closure of a bag is made after the bag is filled, and that the seamformation methods and methods of seam protection employed on the sides and bottom of the bag, or their equivalent, cannot practically be applied to the top, except by machine sewing. 35 Machine sewing is expensive andis practiced generally by only the relatively large users of bags.

In hand sewing the usual method is merely to bring the meeting edges of the top together after filling the bag, and to hold them by one or two lines of hand stitching through the fabric. This has not proved satisfactory largely because the threads of the hand stitching cut the paper at the needle holes and allow sifting. Consequently,

a type of bag has been proposed known as the slack top, in which the fabric is formed in separated layers near the top of the bag, one of said layers being foldable over the contents before the other layer is stitched to close the bag.

In the practice of my invention, I employ a bag of the slack top type, and I provide in the blank 1, as shown in Figure 2, a construction of the fabric such that, while the main body of the sheet comprises burlap solidly cemented to the creped paper, along that edge of the blank which 5 is to form the top of the bag, the burlap 1a and the paper 11) are detached forming separate flaps. When the bag has been filled as shown in Figure 5, the first operation is to fold the paper flaps 1b inwardly to cover the contents 5, as will be readily understood, and then to join the burlap flaps 1a. by any suitable method such as the line of stitching 6 to close the bag. Thus there is formed a non-sifting construction of the top in a hand-sewn closure which is equal to the best results obtained by machine sewing. My invention is directed to improved constructions in slack top bags or in other constructions, and methods of making them.

In the production of a blank of this character, 100 it has hitherto been the practice to use precreped paper and to leave one edge of the paper or burlap free of cement. This gives a flap of single thickness, however, and is relatively weak. Where the cement is bitumen or the like, relied 5 upon for waterproofing, the flap formed in this way is not waterproofed. In commercial prac-- tice, I prefer to employ a composite sheet formed of paper creped by means of a thermo-plastic adhesive substance such as asphalt, and adheno ness, at least in part.

sively joined to the backing of burlap or other fabric by the adhesive used in the creping operation. Here, inasmuch as it is usual to coat the entire sheet with the creping adhesive, special means may be required to produce the desired form of blank. An exemplary creping operation using a thermo-plastie adhesiveis set forth in my Reissue Patent No. 17,633,'and I haveshown in Figure 1, a creping apparatus employing such a process and embodying the improvements of my co-pending application Serial No. 474,578, filed August 11, 1930. A creping cylinder '7 is provided, the temperature of which can be carefully controlled, and a coating of the heat-plastic substance is produced thereon by 'means of coating rollers 8, the outermost of which turns in a pan of the heated thermo-plastic substance 9. The paper web 10 is led to the creping cylinder and pressed into contact with the adhesive coating thereon by a back-up roll 11. It is removed from the cylinder and creped by a doctor 12. Before the adhesive on its surface has cooled sufliciently to lose its tackiness, I press a web of burlap 13 into contact with it by means of rollers 14, the web being fed from a roll of burlap 15. In the pinch between the paper and burlap, along one edge, I introduce a narrow piece of paper 16, from a roll thereof 17, so that it, instead of the burlap, will be cemented to the main paper web. The narrow paper 16 will preferably also be creped and waterproofed; and it serves not only to free the flap 11; from the burlap, but may also strengthen the flap by making it double thick- If the paper web 10 and the burlap web 13 have the width of a plurality of bag blanks, as many of the paper strips 16 may be run therebetween as is desirable acrossthe width of the sheet, d the composite fabric appropriately slit into pieces of the required size. The main creped web 10 may be narrower than the burlap 13, and the inserted flap 16 may produce the width of the paper layer to the width desired.

As thus described, the flap 1b in Figure 2 would itself comprise two thicknesses of paper, at least in part; but at the point of attachment of the paper to the burlap, which is a point of same strain, there is but one thickness of paper. I correct this defect by incorporating another web in the combined fabric at the point of weak- -ness. One method of doing this is to run a strip of open mesh fabric, which will be penetrated by the thermoplastic adhesive partly between the paper web 10 and the burlap 13, and partly between the paper web 10 and the strip 16. This construction isshown in Figure 8. The open mesh fabric is indicated at 1611.

A method which I prefer comprises securing a strip 10a of paper to the main web 10. The strip may be gummed or otherwise secured to the web over the line beneath which the edge of the strip 16 will lie, and is preferably secured there prior to the creping operation, so as to be con jointly creped with the main web 10.

The creped strip 16 is preferably waxed. By this improvement I not only increase the waterproof characteristics of the flap but provide.

against such binding of the folded-over portions ofthe flap as would cause them to tear in use. The waxed surface of the strip 16' enables it to slide against other surfaces in contact therewith.

The wax may instead or additionally be applied -to the free edge of the paper (the flap 1b in Figure 2), usually on the side opposite the asphalted side.

As pointed out hereinabove, it is not essential that the free flap be of double thickness throughout. In some instances it may be found desirable not to make the entire free flap of double thickness unless a gummed tape or other reinforcement be used at the line of separation, for the reason that the double paper is stifier and consequently more apt to tear along the line of weakness unless reinforced. Furthermore, to make the entire flap of double thickness and in addition to reinforce the line of separation with gummed tape or the like involves relatively increased expense. In most instances I have found it advantageous to employ a main creped web narrower than the burlap, and to run the waxed creped strip just an inch or so under the edge of the main creped web, so that the adhesive, such as asphalt, holds the flap in place. This gives a very soft and pliable flap, waterproofed by the wax and in which, as a rule, it is not necessary to employ a reinforcement.

The narrow strip of waxed and creped paper used as just described, may be of a different or heavier basis weight than the paper used in the body portion of the bag or other structure. This is 100 distinctly advantageous in that the weights of the body and of the flap may individually be proportioned to the requirements of each, whereas hitherto it has been possible to increase the weight of the flap only by a similar increase in the weight 105 of the body fabric.

My invention is usefulnot only in the construction of bags, but also in the making of other structures in which a protected juncture is to be made between different portions of composite 110 fabrics As an example, but without limitation, my invention may be employed in the'manufacture of bale covers and the like, where it is designed to sew with a hand needle to close the wrapping on the bale. Nor need the fabric juncture be effected by sewing. My process of producing a free flap and the result thereof is applicable to interfolded or interleaved constructions, whether cemented, sewn, or otherwise fastened, or not, as desired. Cotton sheet g, Osnaburg, or any other: type of reinforcement may, of course, be substituted for the burlap. Hence, it will be understood that my invention is not limited to the particular composite fabric shown and described, nor to the method of forming a bag 125 or other structure from the blank which has been used as the exemplary embodiment of my invention for purposes of description.

free, forming a plurality of closing flaps, one at least of the surfaces of the flap of the creped paper web being waxed to decrease friction between overlapping portions thereof in use.

2. A formed bag of a composite fabric of creped paper and a backing material joined together throughout their length excepting at the top of the bag, where said paper is free from said backing and forms a separate closing flap, said separate closing flap being of double thickness throughout, one at least of the surfaces of said flap being waxed. 4

3. A formed bag of burlap and creped paper, said burlap and said creped paper being cemented together throughout their extent excepting at 1 the top of the bag, where said paper is free from said burlap and forms a separate closure flap, One at least of the surfaces of said flap being waxed to permit slippage, and a third web forming a reinforcement for said paper covering the line of 7 separation thereof from said burlap.

4. A formed bag of burlap and creped paper, said burlap and said creped paper being cemented together throughout their extent excepting at the top of the bag, where said paper is free from said burlap and forms a separate closure flap, said separate flap comprising throughout two layers of paper.

5. A blank of bag-forming or the like material comprising a-web of creped paper and a Web of cloth, said paper being narrower than said cloth and said webs cemented together, whereby a marginal edge of said cloth is left free, and a strip of creped and waxed paper narrower than said web and having an edge portion interleaved between said paper web and said cloth, said strip extending substantially to the edge of said cloth.

6. A blank of bag-forming or the like material comprising a web of creped paper and a web of cloth, said webs cemented together excepting along an edge portion, a strip of creped paper joined to the free edge of said paper web, and a reinforcement of open-mesh fabric attached to said paper web over the line of parting of said web from said cloth.

'7. A blank of bag-forming or the like material comprising a web of creped paper and a web of cloth, said webs cemented together throughout their extent excepting along a marginal edge, the free portion of said creped paper being joined to v a waxed paper band, and another web forming a reinforcement at the point of separation of said paper and said cloth.

8. A bag formed of a blank, comprising two webs joined together substantially throughout their extent excepting along at least one marginal portion and another web forming a reinforcement for one of said webs, covering the line of separation and extending upon both sides thereof.

9. A bag formed of a blank of material, comprising a web of stretchable paper and a web of cloth, said webs having points of adhesive-union excepting along at least one marginal portion thereof, and a separate web of Waxed paper cemented to said stretchable paper throughout said marginal portion.

WILLIAM WALLACE ROWE.

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