US 3495764 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Feb. 17, 1970 w. B. CRANE SLIT BAG FOR PRODUCE AND THE LIKE Filed April 17, 1968 m m E V m Warm! 6f Gem/E Zak/v57 7 weal United States Patent O US. Cl. 229-53 7 Claims ABSTRACT OF THE DISCLOSURE A plastic bag for packaging produce, such as citrus fruit and the like, formed with parallel vertical slits in parallel rows, the slits in each row being longitudinally spaced from one another, the slits in alternate rows being approximately aligned in directions transversely of the slits, and the slits in adjacent rows being offset or stag-.
gered from one another. Each slit has at each of its ends a punch hole or aperture. When the bag with these slits is stretched transversely, as by a contained load of oranges, for example, the slits open up, and the stressed region of the bag runs along edge regions of the opened and transversely elongated slit holes. The slit wall material has no sharp slit ends, or indents, and splitting at the slit ends is completely prevented. If the bag is stressed to destruction, transversely of the slits, portions of the wall material between consecutive slits of a row undergo tensile failure; but a larger stress is required to cause such failure than would ever be encountered in practice.
BACKGROUND OF THE INVENTION This invention relates generally to the packaging art, and more particularly to a novel packaging bag made from a sheet or film of thin, pliable, transparent plastic, slit for the dual purpose of allowing air to circulate into the bag for ventilation of produce packed therein, and of ready expansion and conformity to articles packed therein, such as oranges, for example.
The present invention may be regarded as an improvement on the bag disclosed in my prior Patent No. 3,245,- 606. The bag there disclosed was composed of two sides, one of which was slit for air circulation and for flexibility and conformity to contents, and the other side was unslit to aid in preservation of the general bag shape, and which also contributed strength and stability. The slits of this bag were in parallel rows, with the slits in alternate rows being aligned in a transverse direction of the rows and the slits in adjacent rows being offset lengthwise of the rows, so that the slit wall readily stretches in said transverse direction. The bag of this patent was well adapted to carry out its intended use, i.e., packaging bunches of grapes, with the packages normally resting on the unslit sidewall of the bag. If these bags, however, were filled with relatively heavy articles of produce, as oranges, however, and were held in any position in which the oranges might tend to materially stretch the slit sidewall, they were prone to tear at the ends of slits. Accordingly, they were not found suitable for packaging such articles as oranges, particularly if the bags were lifted from their upper ends, because of this ready proneness to tearing.
The purpose of the present invention is to improve the bag discussed above in a way which would strengthen it against tearing.
SUMMARY OF THE INVENTION According to the invention, the bag is slitted like that of the bag of my aforementioned patent, excepting that two end portions of each slit are punched out, forming holes or apertures, preferably circular in shape, so that at the exact point of the sharp end of each split in the former construction, and where tearing stress was formerly concentrated, there is now an edge portion of material which extends transversely of the slit. This edge, in the preferred illustrative embodiment, curves around and back to the slit, at a point spaced inwardly along the slit from said transversely extending edge portion of material. It is now found that when the slit wall of the bag is stretched transversely of the slits, the slits open up, to increase air circulation, and to conform to whatever articles are packed in the bag. But also, and more importantly, the stresses transversely of the direction of the slitting meet no sharp slit ends; and there being no sharp slit ends, there is no propensity to tear. Actually, the aforementioned transverse edge portions of material tend to straighten out under this stressing, and become aligned with the direction of stress. Hence, all places where tears might start are eliminated, and the bag becomes tremendously strong against transverse stretching.
DESCRIPTION OF THE DRAWING FIG. 1 shows a bag in accordance with the invention, containing produce of a type for which it is especially designed, in this case oranges;
FIG. 2 is a side elevational view of a bag in accordance with the invention;
FIG. 3 is a transverse section taken on line 33 of FIG. 2;
FIG. 4 shows a fragmentary portion of a wall of the bag of FIG. 2, to an enlarged scale, and showing the manner in which it becomes stretched and its slits open up upon being subjected to a transverse stress, such as caused by loading the bag with relatively heavy produce, such as oranges; and
FIG. 5 shows a fragmentary section on line 5-5 of FIG. 4.
DESCRIPTION OF THE PREFFERED EMBODIMENT The packaging bag 10 of the invention is illustrated in the drawings as made from a tubular film of thin, pliable, or flexible transparent plastic, closed at the bot tom as by heat sealing, as indicated at 11. It will be clear that the bag could alternatively be made from two side panels, heat sealed at the longitudinal edges and at the bottom. In the present illustrative embodiment, designed especially for packaging of citrus fruit such as oranges, indicated at 0, the transverse width of the bag, when laid flat as in FIG. 2, is 7 inches, and its length is 19 inches. It will, of course, be understood that the bag may be made to different dimensions to accommodate different sized produce, and different quantities thereof. The heat sealing along the bottom edge 11 forms the initial plastic tubular member into two opposed sidewalls 12, adapted to lie flat, adjacent one another as indicated.
Preferably, a narrow band at the lower end of the bag is left unslitted, and preferably, approximately the upper 6 inches of the bag are also unslitted. The two side walls 12 between these unslitted portions are formed with parallel matching rows 13 of longitudinally spaced, co-linear slits 14, running longitudinally of said side walls. As seen clearly in FIG. 2, the slits in alternate rows are approximately aligned in a direction transversely of the rows, while the slits in adjacent rows are offset from one another longitudinally of the rows. Thus, the slits in each row are located opposite the spaces between slits of the adjacent rows; and, preferably, the spaces between slits of a given row are centered longitudinally of the rows with the center points of the slits of the next adjacent rows.
The unique feature of the invention is that punchholes or apertures 16 are formed at the ends of the slits 14, the holes being preferably, though not necessarily, of a generally circular outline. It would be equivalent to have the punch holes somewhat elliptical, particularly if their major axis is perpendicular to the slits. Other curved contours may of course be contrived. These holes 16 must in any event be smooth-curved throughout the outer end regions thereof, so as to avoid sharp or narrow slit-ends, re-entrant angles, or indentations affording points of stress concentration when the bag is stretched laterally. It may be said that the holes have either smooth-curved, or nearly straight, edge portions facing and extending substantially transversely of or across the corresponding end portions of the slits, so that when the bag is transversely stretched, these edge portions will be substantially straight, or approach straightness, or be of only small curvature, and will in no event contain any sharp notch or indentation at which stress concentration could develop.
Without intention of limiting the invention, but by way of setting forth a slit pattern which has proved successful, certain slit dimensions may be given. Thus, a given slit 14, taken together with its two punch-holes 16, may have a length dimension d, measured between the outer limits of its punch-holes 16, equal to approximately 1.2 inches, and the punch holes, assumed in this case to be circular, as shown, may have a diameter of .25 inch. The distance between punch holes at the adjacent ends of successive slits in a given row 13 in the present preferred embodiment, is approximately .5 inch and the distance between successive rows of slits 13 is approximately .6 inch. The ratio of hole diameter to slit length is thus, rounded out, of the order of to 1, and the distance between successive rows of slits is of the order of one-half the length of a slit. It may be further observed that, with dimensions of the order herein given as representative, the holes 16 are staggered, or disposed in zigzag rows transversely of the bag walls, and that substantial portions of the holes in said transverse rows are in rectilinear alignment. It will be understood, of course, that the dimensions given are those of a present preferred embodiment and which have demonstrated unexpected strength, when tested to destruction.
FIG. 1 shows the bag of the invention loaded with oranges. Assuming the oranges to be sized properly for the bag, the tendency, with the amount of give afforded by the slits in the walls, is for the oranges to arrange themselves in four columns, as seen in FIG. 1.
FIG. 4 shows to an enlarged scale a portion of the slit side wall subject to substantial lateral stretch, with forces for more than enough to destroy the slit wall of the aforementioned bag of the prior art. Under any material lateral stretch, as a matter of fact, e.g., simply by suspending the bag from its top while loaded with oranges, the slits often tear out at their ends. The side wall of the bag of the invention, under high lateral tension (with a given degree of longitudinal tension), however, elastically distorts to or toward the configuration repre sented in FIG. 4. The slits and circular openings open up wide, and the bag material is tautened along lines or bands 20 of the material that run generally transversely of the bag, and there are no breaks, cuts, or indentations in the edges of these lines or hands, so that the bag is actually immune to tearing. These lines or bands 20 will be seen to be adjacent and parallel to the outer, arcuate edge portions 22 of the holes. It will be understood from FIG. 4 that, under transverse stress, applied to the bag wall, these holes 16 open up and elongate in the direction of the stress, and that the outer edge portions 22 of the holes 16, across from the slit ends, approach straightness as the stress increases.These edge portions 22 define longitudinal edge portions of the stress lines or bands 20. It will also be seen that in the present preferred embodiment, these narrow tautened bands 20 extend between the outer edge portions 22 of elongated holes 16 of ofiset slits of successive slit rows 13 in a Zigzag pattern. In FIG. 4, the tautened band will be seen to be narrowest adjacent the edges of the holes 16, and wider therebetween. The zigzag band automatically increases in width, and also becomes progressively straighter, as the tension increases, until finally, in a position assumed at very high transverse stress, i.e., beyond any likely to be experienced in practice, the bands 20 may become substantially straight. The material of the bag between a pair of transversely aligned slits, when under transverse stress, forms two inclined, generally loose and flexible flaps 26, joined at the edges to adjacent portions of the tautened bands 20 on opposite sides thereof.
The accomplishment of the invention, then, is the provision of a bag having a pattern of slits with special holes at the ends thereof, in which, when the side wall of the bag is transversely tensioned, the slits open up, and the holes widen or elongate, creating tautened, generally parallel bands of material, which are devoid along their entire lengths of any sharp corners, re-entrant angles, or indentations, and which are therefore completely immune to tearing. They may be burst by increasing the tension sulficiently, but the failure is by reason of stretching beyond the elastic limit rather than by tearing. Moreover, the tensile strength is so great that any kind of failure at all is far beyond the results of any stressing that would be encountered in practice. To all intents and purposes, the invention provides a slit, laterally expansible bag which is completely immune to tearing no matter how much lateral tension may be created in practice owing to crowding in of contents.
1. A bag for packaging produce and the like, comprised of a sidewall formed of transparent, flexible, plastic film, there being parallel rows of longitudinally spaced slits in said sidewall, running longitudinally thereof, the slits in alternate rows being susbtantially aligned transversely of the rows, the slits in each row being located opposite the spaces between slits in the rows adjacent thereto, and there being holes in said sidewall at, and opening from, opposite ends of said slits, said holes having smoothcurved edge portions facing and extending transversely of the corresponding end portions of the slits.
2. The bag of claim 1, wherein said holes are substantially circular in form.
3. The subject matter of claim 1, wherein the midpoints of the slits of each longitudinal row are positioned substantially in alignment with the mid-points of the spaces between holes at the proximate ends of consecutive slits or adjacent longitudinal rows.
4. The subject matter of claim 3, wherein the holes at the end of slits in alternate longitudinal rows of slits are in a zigzag relationship with holes at the ends of the slits of the intervening rows of slits, with substantial portions of the holes in said zigzag relationship being in rectilinear alignment.
5. The subject matter of claim 1, wherein the spaces between successive slits of each row are greater than the lengths of the slits of adjacent rows.
6. The subject matter of claim 2, wherein the diameters of the holes are of the order of one-fifth of the lengths of the slits.
7. The subject matter of claim 6, wherein the spaces between successive rows of slits are of the order of half the lengths of the slits.
References Cited UNITED STATES PATENTS 2,141,752 12/1938 Hoarle 22944 2,689,678 9/1954 Wendt 22953 3,040,966 6/ 1962 Crane 22953 3,186,625 6/1965 Mead et al. 22953 DAVID M. BOCKENEK, Primary Examiner