US2785720A - Plastic bag - Google Patents

Description

March 19, 1957 R. H. wlKLE.

PLASTIC BAG Filed May 13, 1953 FIG l l2 lO Il Flc 6 ATTORNEY United States Patent O PLASTIC BAG Richard H. Wikle, Atlanta, Ga.

Application May 13, 1953, Serial No. 354,678

3 Claims. (Cl. 150-1) This linvention relates to plastic lbags, and more particularly to strong, thin lmed reinforced bags made of plastic or synthetic rubber-like sheet material.

Bags for flour, feed, seed, meat, chemicals, vegetable products, mineral products, and the like, have heretofore been made of paper, fabric, a combination yof plastic and fabric, a combination of paper vand fabric, and the like, but such prior art structures have not been found completely satisfactory. For example, the prior art paper bags when wet have had a tendency to tear or separate along their 'seams while the woven fabric bags have not had sufficient-ly close weave to insure that finely ground material contained therein will not sift out. Further, fthe prior art bags made of heat scalable material such as rubber hydrochloride and polyethlene, like the paper bag, have had a tremendous tendency to tear when containing heavy material. Other prior art Ibag structures have been found to be expensive to manufacture or complicated in structure.

Accordingly, it is an object of my invention to provide a plastic bag which will overcome the disadvantages attributed rto the prior -art bags, and which has ya maxi-mum -tensile strength so that it does not tear easily.

Another object of my invention is to provide a plastic bag having extreme thinness and being reinforced in lsuch a way that -it is substantially impossible to tear under normal 4stress and strain conditions.

Another object of my invention is -to provide a strong plastic bag of thin, reinforced plastic sheet material which is capable of being coated with insecticidal chemicals on the outside thereof with no danger of these `chemical-s penetrating within.

Another object of my invention -is to provide a plastic, multi-ply bag having maximum tensile strength, good insulating qualities, and being so constructed that it will avoid the normal sweating characteristics of the prior art bavs.

Ether and further objects and advantages of my invention will become apparent from the following description when taken in conjunction with the `accompanying drawings in which like characters of reference designate corresponding parts throughout the several views, and where- Fig. l is -a plan view of a blank from which a bag made in accordance with my invention is constructed.

Fig. 2 is a front elevation of `a bag constructed from the blank shown rin Fig. l.

Fig. 3 is an enlarged fragmentary view of a detail.

Fig. 4 is a cross-sectional view taken along -line 4 4 in Fig. 2.

Fig. 5 is a fragmentary top view of the detail shown in Fig. 3.

Fig. 6 is a plan view of one ofthe blanks from which a multiply bag is made according |to my invention.

Fig. 7 is a front elevation of the multi-ply bag made according to my invention utilizing two 'blanks such as the one shown in Fig. 6.

' 2,785,720 Patented Mar. 19, 1957 Fig. 8 is a cross-sectional view taken a1-ong |line `8 8 in Fig. 7.

In the embodiments of my invention chosen for purpose of illustration, Fig. 1 shows a blank of thin sheet material which may be made of plastic or synthetic rubber material, cellophane, regenerated cellulose, cellulose acetate, cellulose acetate butyrate, celluose nitrate, ethyl cellulose, or any such cellulose derivatives, as well as products obtained by the polymerization of vinyl compounds and other plastic materials used in the plastic and synthetic rubber industry to make thin plastic or plastic- `like films. As vshown in Fig. 1, `this blank has a `smooth substantially rectangular border portion 10 around the outside, and the central or interior portion of the blank is formed of a thin continuous sheet 11 which is crisscrossed by interseecting reinforcing ribs, the vertical ribs being denoted by numeral 12 and the laterally disposed ribs by numeral 13. Vertical ribs 12 extend continuously `between opposite horizontal portions of border portion 16 while horizontal ribs 13 extend continuously between opposite vertical portions of border portion. It will thus 'be seen that the blank from which my bag is made is economical in the use of material because the material which would otherwise form a thickness equal to the thickness of the border portions is forced up into the ribs which criss-cross and provide adequate protection for the thin sheet 11, `so Ias to prevent tearing thereof.

The reinforced blank of thin plastic sheet material from which my lbag is made, may be formed by casting, extruding, calendering on engraved surfaces, or 'by other methods known in the plastic and synthetic rubber industry for making thin fihns of sheet material and the like.

As shown in Fig. 2, `the blank of Fig. l is folded upon itself in a manner customary in the bag-making art, and the opposite smooth vertical edges of border portion 10 `are fastened together Iby glueing, heat sealing yor other processes known in the bag-making art -to -form a cylinder. Thereafter, one horizontal edge portion of border portion 10 is sea-led against itself while `the other horizontal portion is left open to receive the contents, -after which it is sealed `as described before.

Fig. 4 is a cross-sectional View showing the completed envelope Iof the bag with the smooth lborder portions of the blank overlapping and fastened together. From this view, it will be noted that the exterior wall of lthe bag is substantially smooth, whereas the innerwal-l of the bag is provided with reinforcing ribs 12 and 13. From Fig. 4, it will be noted ythat the thin sheet 11 which is integral with the border portion 10 presents a smooth outer sur- :face which readily lends itself :to printing thereon `of information regarding the contents of the bag or other ornamentation.

A modied Iform of ymy th-in film plastic ybag is shown in Figs. 6, 7 and 8, this modification being a multi-ply bag using two of the blanks shown in Fig. l. These blank-s are 'tted together and form a border 14 within which are disposed parallel thin sheets 1-5, 15 which are spaced apart by inwardly projecting criss-crossed intersecting ribs 16, 16', which are respectively integral therewith. These criss-crossed ribs =are `substantially identical with the intersecting ribs 12 and 13; however, each of the ribs 16 is joined to its respective complementary rib 16 by heat sealing, glueing or other process common `in the bagmaking art. It may thus be seen `from Fig. 8 that ribs 16, 16 'and ' thin lms 15, 15 define a plurality of separated dead Aair spaces 17 which form excellent insulating areas.

As described for the formation of the bag =by use of a. single blank, the blank shown in Fig. 6 is Ifolded upon itself ina manner customary in the bag art; however, the smooth edges or border portions 14 are joined to their respective border portions as illustrated in Fig. 8 land are respectively fastened together by glueing, heat sealing or ICC,

' Y .s other process common in the bag-making art to form a Vertical seal along the bag as shown Vin Fig, 8. On rthe other hand, the upper and lower border portions of the bag are merely sealed in 'a manner similar to the sealing of the bag illustrated in Figs. 2 and 4.

it is to be noted that when Yforming a bag as a container for material such als our, it may be found desirable -to select a material, from the materials mentioned above, Which will allow limited breathing or osmotic :air changes within the bag and yet prevent the our from sifting out. Thus, a thin cellophane would probably be selected since it provides a web Ahaving :suicient textureV Y of the materials which it is to contain.' VIt will be equally obvious that other changes may be'made in theiembodiments selected for lillustration Without rdeparting from the scope of my invention as defined by the appended claims.

I claim: I

1. in an imperforate bag, a wall made of p'lastic'sheet material, said sheet material having Ya substantially rectangular smooth, relatively thick border portion and lan sesamo i Y Y e e interior port-ion, said interior .portion comprising a relatively thin continuous sheet joined to said border portion, said border portion extending around said interior por tion and `defining opposite portions and an upper portion and a bottom por-tion,rand intersecting reinforcing libs integrally connected to said sheet 'and criss-crossed 'across the surface -of said sheet, Vcertain ribs joining said opposite portions of ysaid rborder portionand forming with s-aid continuous sheet a thickness substantially equal to the `thickness of said border portion.

2. The structure defined in claim 1 wherein said op-V posite portions of said 'border portion lare joined to form 'a cylinder and said bottom portion of said border portion is -sealed against itself.

3. The structure defined in claim 1 `including -a second plastic wa-ll joined Ito said rst mentioned Wall `ari-:l Vdefining with said relatively thin continuous ysheet of said iirst mentioned wal-1 and said intersecting ribs a plurality V@of closed air spaces.

References Cited in the le of this patent UNITED STATES PATENTS 1,785,101 Sutherland Dec. 16, 193() 1,934,547 Little Nov.v 7, .1933 1,992,152 Yeate-s Feb. 19, v1935 2,046,146 Brady June 30, 1936 2,584,633 Southwick Feb. 5, 1952 Y FOREIGN PATENTS f 306,330 Great Britain Feb. 21, 1929

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