US3360182A

US3360182A - Easy opening container

Info

Publication number: US3360182A
Application number: US576154A
Authority: US
Inventors: Charles L Gunn
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1966-08-30
Filing date: 1966-08-30
Publication date: 1967-12-26
Anticipated expiration: 1984-12-26

Description

Dec. 26, 1967 c. 1.. GUNN 3,360,182

EASY OPENING CONTAINER Filed Aug. 30. 1966 2 Sheets-Sheet 1 Fig. 1

l3 INVENTOR.

Charles L. Gunn BY ATTORNEY Dec. 26, 1967 c. L. GUNN 3,360,182

EASY OPENING CONTAINER Filed Aug. 30, 1966 2 Sheets-Sheet 2 INVENTOR.

Charles L. Gunn United States Patent 3,360,182 EASY OPENING CONTAINER Charles L. Gunn, Cincinnati, Ohio, assignor to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio Filed Aug. 30, 1966, Ser. No. 576,154 6 Claims. (Cl. 229-51) This invention relates to an easy opening container adapted to facilitate price marking of the packages contained therein and to permit the formation of display trays from the container without danger of package damage and more particularly to such an easy opening container in which the contents comprises a plurality of layers of packages, each layer consisting of a multiplicity of such packages. As such, this invention is an improvement to the easy opening container disclosed in United States Letters Patent 3,185,382, which issued to F. C. Nunn on May 25, 1965. As used herein, the word container denotes the receptacle within which a multiplicity of individually packaged units of product may be contained. The individual packages will be referred to as carton, package or the like.

One of the current trends in modern retail outlets for consumer goods is the application of a price on each of the packages displayed for sale in the store. The reason for this trend is that the size of such outlets has increased substantially since the day of the corner grocer and the variety of products and number of brands handled have caused confusion in price determination by cashiers at check-out counters. The most usual method by which price marking is accomplished by a stock clerk is to rip open the top closure flaps of the container and apply the price marking to the top of each of the cartons of product contained therein while the cartons are in the closely spaced relationship caused by confinement in the container. Occasionally, it has been found necessary or more expedient to cut a portion of the container around its periphery so as to remove the closure intact, possibly along with a continuous attached strip of the side and end panels contiguous thereto. This is convenient and relatively safe when the contents of the container are packaged in metal cans or the like, but presents a serious problem of product damage when the packages are constructed of materials which can be damaged when contacted by a knife, e.g., cardboard.

Another of the modern trends of retail outlets for consumer goods has been to attempt to open the containers of the product which is intended to be placed on the store shelves in such a manner as to result in the formation of display trays. In this way one or more layers of the packaged product may be handled as a unit, thereby re ducing the time necessary for stocking the shelves and facilitating the taking of periodic inventories of the gOOdS maintained on display in the outlet, as frequently required by accounting systems.

Many devices have been addressed to the satisfaction of either or both of the above trends, but to date none has been reasonably successful in solving the problems in an economical and facile manner when the contents of the container comprises a plurality of layers of packages which are substantially smaller in size than the layer as a whole. It has been found that under such circumstances, the layers become disrupted upon the opening of the container and during the associated steps involved in initially separating the layers of packages along the line of fracture of the container. For example, if a top-loading, end-opening, trayforming container has multiple layers of packages contained therein and the container is intended to be formed into two trays, each of which carries layers of packages, the suitcase manner of separation of the trays during the opening operation causes some of the packages to fall Patented Dec. 26, 1967 from their packed position to the floor and can cause damage to the packaged product. In opening such a container, the container is placed on end with the end to be opened uppermost, then the case is split vertically and each of the trays is rotated to a horizontal position. It is during the pivoted movement of the trays that the packages fall out and the layers are disrupted.

In addition to the foregoing, many of such devices are designed in such a manner that a stock clerk is not able to readily understand the procedure to be followed in their utilization and sometimes is not even aware of their incorporation in the container.

It is an object of the present invention to obviate the above difficulties.

Another object of the present invention is to provide an economical, easily opened, tray-forming container constructed entirely from materials normally used in manufacturing containers, involving no new manufacturing operations, possessing a simplicity of design such that its function will be readily understood by persons in the retail consumer industry, and adapted to facilitate separation of layers of packages during opening without problems of manual transfer or reorganization of such layers.

Briefly stated, in accordance with one aspect of this invention, a container is provided which has in combination two pairs of marginally connected and alternating end walls and side walls, and bottom and top closures. The side walls substantially exceed the end walls in width. The ends of the container blank lie Within the confines of one of the end walls, thereby dividing the end wall into two portions, each of which has a pair of oppositely disposed end fiaps connected to it. The combined widths of the end wall portions is approximately equal to the width of the other end wall, which is slotted in its central portion. The end wall portions are secured in juxtaposition by means of a manufacturers joint. The container has a plurality of layers of packages therein, the layers being parallel to the planes of the sidewalls and having an interface along a plane approximately centered between the sidewalls. The closures comprise substantially rectangular, full width side flaps having a dimension from hinge line to free edge which is about one-half the width of an end wall and similarly dimensioned end flaps. The side flaps are folded inwardly with the free edges thereof abutting and the end flaps are folded inwardly and secured in overlapping relationship with the side flaps.

Although the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the present invention, it is believed the invention will be better understood from the following description taken in connection with the accompanying drawing in which:

FIGURE 1 is a plan view of the outer surface of the container blank, as cut, scored and printed prior to folding and to the application of the manufacturers joint in the formation of a fiat container tube from the blank;

FIGURE 2 is a plan view of the flat container tube prior to squaring-up of the container;

FIGURE 3 is a perspective view of the erected and squared container in condition to receive the product to be packaged therein; and

FIGURE 4 is a perspective view of the container in the process of being opened.

Referring to FIGURE 1 of the drawings there is shown a plan view of the exterior surface of a container blank of one embodiment of the present invention. The blank consists of side walls 10 and 1.1, with an end wall 12 located therebetween. Another end wall 13 (see FIG- URES 2 and 3) is constructed in two parts, one lying at each of the oppositely disposed ends of the container blank. The end wall portion 13' is marginally interconnected with the side wall 19 and end portion 13" extends outwardly from side wall 11.

The side walls and end walls are defined by the pattern of scoring shown.

Score lines

14 and 15 define, respectively, the top and bottom limits of each of the panels or walls comprising the container, providing the fold line intermediate the above-mentioned side and end walls and the outwardly extending side flaps and end flaps described hereinafter.

Score lines

16, 17, 18 and 19 intervene the respective side and end walls and constitute the vertical corners of the container when it is erected for packing.

Side flaps a, 10b, 11a and 11b extend outwardly from the top and bottom of the container blank, each being integrally attached to a correspondingly numbered side wall. End flaps 13'a, 13'b, 12a, 12b, 13"a and 13b are marginally interconnected with correspondingly numbered end walls or end wall portions along substantially the full Width thereof, extending outwardly therefrom from the top and bottom of the blank. As shown, the juxtaposed end and side flaps are separated by cuts 16, '17, 18' and 19' located at opposite sides of each of

score lines

16, 17, 18 and 19, respectively. The end and side flaps are each substantially rectangular and approximately identical in width (i.e., the flap dimension from score line to distal end) and as is usual in the case of containers, this dimen sion is preferably equal to one-half of the Width of the end walls 2 and 13 (i.e., the dimensions between the

score lines

17 and 18 and between

score lines

16 and 19 in the formed container). So constructed, the side flaps of the container cover substantially the entirety of the area comprising the top and bottom closures in usean aid in eliminating the possibility of dirt entering the sealed container.

The side walls 10 and 11 are substantially identical in dimension and have a width substantially exceeding the width of

end walls

12 and 13, which are also substantially identical in dimension, whereby to form a rectangular receptacle in use. In this connection, the width of the end wall portion 13 intermediate score line 16 and the distal end 20 of the blank plus the width of end wall portion 13 intervening score line 19 and the distal end 24 of the blank are such that when placed side-by-side they present an effective or composite width equal to that of the end wall 12 between

score lines

17 and 18. It should be noted that in the embodiment illustrated the width of end wall portion 13' and end Wall portion 13" are not equal. This constructional detail, the purpose of which will be explained more fully hereinafter, is a desirable feature but it is not essential to the practice of the instant invention. It is contemplated that the present invention is also useful when applied to container embodiments in which the said wall portions are of equal width. In connection with a container having the

portions

13 and 13" of dissimilar width and being approximately 13" long, 6%" wide, and 13 deep, it has been found that the width of the larger of the two end wall portions should desirably exceed the width of the other by an amount of at least about 1", thus making the seam fall at least about /2 from the center line of end panel 13.

End flaps 12a and 1212 are slotted in the central portion thereof as shown at 22 and 23. The

slots

22 and 23 of the illustrated embodiment are out of alignment with the center line of the end flaps of the end wall 12, i.e., are located off-center on the

end flaps

12a and 12b. Alternatively, the slots can be placed on-center since the present invention can be used in connection with either slotting arrangement; however, the offset slot presents some strength advantages, as will be described later, and for that reason is preferred. While these slots may be placed ofi center in any direction, it is advantageous for the eccentricity to be governed by the width and location of the end wall portions 13' and 13". The length of the sections of the end flaps 12a and 12b between

slots

22 and 23 and the cuts 17' can be approximately the same as the length of end flaps 13'a and 13'b of the end wall portion 13. Similarly, the length of. the sections of end flaps 12 and 1222 between the

slots

22 and 23 and the cuts 13' should be approximately the same as the length of the end flaps 13"a and 13"b of the end wall portion 13". From the above it will be seen that the section of the slotted end flap located adjacent to the sidewall from which extends the end Wall portion of greater width will preferably be the section of the slotted end flap having the greater length.

Each of the

slots

22 and 23 extends from the outer or free edge of the flap in which it is made to a point located outwardly from the score lines 14 and 15, respectively, by an amount equal to about 1. This spacing from the score lines prevents the container from tending to form a fold between the ends of the

cuts

22 and 23 when the carton is squared for use. The tendency to form an additional fold in the container would be extremely undesirable in utilizing the receptacle.

The side flaps 10a and 10b extending outwardly from the side wall 10 are each preferably provided with an area of

printing

25 and 26 in the free edge corners thereof adjacent end fiaps 13a and 13'b', respectively, the ink used being a type which prevents the firm adhesion of glue to the board underlying it. Alternatively,

areas

25 and 25 can be coated with a suitable varnish to prevent firm adhesion thereto. The procedures for so treating selective areas of pack-aging materials are well known and will therefore not be described in detail herein. The lengths of the areas 25 and 26 (i.e., the dimension parallel to the free or outermost edges of the side flaps) are subtantially equal to the full width of the end flaps 13"a and 13"b. The width of the

areas

25 and 26 is regulated by the difference in the widths of the end wall portions 13a and 13b and is equal to the distance by which the edges 24' of the end flaps 13"a and 13!) are removed from the center line of end wall 13 after the manufacturers joint is made. In other words, the widths of the unprinted portions of the side flaps 10a and 10b intermediate the :

areas

25 and 26 and the score lines 14 and 15, respectively, are approximately equal to the length of the end flaps 13a and 13'b (i.e., the dimension thereof between the edges 20 and the cuts 16').

From the above it will be seen that if such printing is employed, it will be placed on the side flaps extending from the side panel adjacent the end panel portion of least width. In the illustrated embodiment, the end flap portion of least width is 13' and for this reason the printing is located as described hereinabove on side flaps 10a and 10:). If the smaller of the two end wall portions had been 13", then the

printing areas

25 and 26 would have been done alongside the oppositely disposed free edge corners of the side flaps 11a and 11b adjacent end flaps 13"a and 13"b.

After the blank is cut, scored and printed as described above, the end wall portion 13' and the attached end flaps 13'a and 13'b are folded inwardly along the score line 16. Next, the side wall 10, end wall 12, the inwardly folded end wall portion 13 and the associated end and side flaps are folded inwardly 180 along the score line 18. This places the

end wall portions

13 and 13" in juxtaposed position with the distal ends of the blank abutting or at least closely adjacent one another and in condition to be united by means of a manufacturers joint.

A manufacturers joint is the seam formed by the container manufacturer and serves to connect the ends of the container blank, forming the container sleeve from the planar blank. As shown in FIGURES 2, 3 and 4, the illustrated embodiment utilizes a taped joint, preferably a tape 21 provided with an integrally formed tear strip the tab of which is shown at 210. Such tapes and the manner in which the same are applied are well known to those of ordinary skill in the art and therefore are not described in detail herein.

While the described embodiment employs the tape along the full length of the distal edges 2020-20 and 24-2424' of the blank, it is also satisfactory to limit the length of the tape 21 (or the alternative form of tape described below) whereby the joint occurs only along

edges

20 and 24 and the end flaps 13'a, 13'b, 13"a and 13"b are not secured in the tapering operation. The full length taped joint is preferred, however, because the same strengthens the container when it is in use.

Alternatively, the manufacturers joint can be made with a tape which itself is removable completely, i.e., is adapted to be peeled from the container. In this case, also, the construction and manner of application are well known and therefore not described in detail.

Another alternative which can be employed is to form a glue flap on the blank, as described in the aforesaid U.S. Letters Patent 3,185,382, and secure the tape in over lying relationship with the end wall portion at the opposite end of the blank by means of soft seal adhesive, staples or any other satisfactory means for removably securing the glue flap whereby to form a manufacturers joint therewith. The disclosure of the aforesaid patent relative to the formation of the manufacturers joint with a glue flap is hereby incorporated by reference.

To use the container, the flattened sleeve shown in FIG- URE 2 is squared and the bottom closure flaps 13b, 13"b', 12b, b and 11b inwardly folded and glued. In accomplishing this, the side flaps 10b and 11b are first folded inwardly and an adhesive applied to the outer surface thereof or to the inner surfaces of end flaps 13'b, 13"b and 12b, as the case may be. Then, the juxtaposed end flaps 13"]: and 13'b and the oppositely disposed end flap 12b are folded into overlapping relationship with the aforementioned side flaps and suflicient pressure applied to adhesively unite them. It will therefore be understood that the full width side flaps will be positioned between the container interior and the end flaps, in position to directly contact the packages to be packed in the container.

Next the packages to be placed in the container are inserted through the open top closure of the container. The packages are arranged in a plurality of layers in the container, each layer consisting of a multiplicity of packages and having perimetrical dimensions approximately matching those of the side walls 10 and 11. (For example, a container having side walls which measure 13 /8" x 6% can hold packages in layers which have face dimensions of about 13 /2" x 6%".) Moreover, the combined thickness of the layers should approximately equal the width of the

end walls

12 and 13 whereby to fit snugly into the container on all sides. The packages can, for example, be accumulated in layers and packed automatically by machines well known to those skilled in the art. If desired, of course, the packages can be packed manually, the packer forming the layers of packages during the packing operation. In any event, the layers are oriented substantially parallel to the planes of the side walls 10 and 11 of the squared container and the interface between two adjacent layers is approximately centered between the side walls 10 and 11. Therefore, the said interface will generally align with the abutting free edges of the side flaps of the top and bottom closures. If all the packages are uniformly sized and oriented in the container, then there would be an even number of layers packed in the container whereby to assure that the said interface is properly placed.

The layers each comprise a multiplicity of packages and, although the present invention is applicable with respect to packages of Widely varying sizes, it finds its greatest utility in connection with packages the size of which are particularly conductive to the opening problems mentioned previously. Such packages have a dimension parallel to the width of the side walls 10 and 11 (i.e., parallel to score lines 14 and 15) which is not greater than onethird of the width of the side walls and is smaller than the amount by which the width of the side wall 10 or 11 exceeds that of the

end wall

12 or 13.

A portion of the packages having the specified dimensions, when contained in a rectangular suitcase style, trayforming container such as that of the aforementioned US. Patent 3,185,382 and in which the end flaps are overlapped by the side flaps in the top and bottom closures, will be located in the gap intermediate the free edges of the end flaps. As a result, this portion of such packages, will be more loosely held in place (by the interior surface of the side flaps) than the packages abutting (and therefore supported by) the interior surfaces of the end flaps, since in the former instance the same length of packages is being held between surfaces which are spaced apart further than the supporting surfaces of the latter instance by an amount equal to two thicknesses of con tainer board. However, when the present invention is utilized, i.e., the easy-opening, tray-forming container is provided with top and bottom closures in which the full width, abutting side flaps are overlapped by the end flaps, then the side gripping forces exerted on the ends of the packages are uniform throughout the container and maintain all packages in the individual layers in place during the opening operation, as will be later described.

Following the packing operation, the top closure flaps 16a, 11a, 13'a, 13"a and 12a are inwardly folded and adhesively united in the same manner as described above in connection with the bottom closure, i.e., with the side flaps to the interior of the end flaps. Alternatively, of course, the flattened sleeve may be squared, the packages inserted and both top and bottom closure flaps sealed subsequently.

Because of the comparative lengths of the end flaps extending from the end wall portions 13" and 13" and the related location of the

slots

22 and 23, each of the side flaps extending from side wall 10 will, upon sealing of the closures, contact all of the individual end flaps in cluded in the respective closures. Thus, side flaps 10a Will underlie parts of end flaps l3 'a, 13"'a, and 12a. Moreover, the side flap 10a will extend across slot 22 so as to permit attachment of the underlying side flap to both sections of end flaps 12a. Similarly, side flap 10b will extend across slot 23- and be attached to both sections of end flap 12b. This arrangement is very important, though not essential to the practice of the present invention, since it will increase the torsional strength of the container substantially as compared with the torsional strength of a similar structure wherein the end wall portions corresponding to portions 13' and 13" are identically sized and the slots centrally located on the end wall flaps. It will also be noted that because of the relationships described above, the printed

areas

25 and 26 will always underlie the part of the end flaps 13"'a and 13"b extending across the abutting free edges of the side flaps 10a and lltb of the top and bottom closures, respectively, and will be contiguous to the manufacturers joint. Such an arrangement facilitates easy separation of the container in the manner to be described.

When the container has been shipped to the retail outlet, opening may be accomplished in the following manner. The container is placed flat with the end wall 12 in the lowermost position. This orientates the container with the side walls 10 and 11 extending vertically and the manufacturers joint located on top. Then the manufacturers joint is removed or severed, as the case may be, thereby dissociating the end wall portions 13' and 13". In the illustrated embodiment the manufacturers joint is severed by means of a tear strip within the tape 21. The tear strip tab 21a is grasped and pulled firmly upwardly to commence the severing action. Following complete removal of the full length strip by continued upward pulling, the tape 21 is severed lengthwise, leaving two separated side portions 21' thereof (see FIGURE 4) adhered to the container, one along each of the edges 28 4040 and 24'-24-24'. Next, the fingers are inserted between the edges 20 and 24- and outward pressure is applied to end wall portion 13" while end wall portion 13' is held in place. As a result, the seal of the top and bottom closures fails at the end thereof adjacent end wall 13. This is due to the fact that the

areas

25 and 26 of side flaps a and 1011 are printed to prevent firm adhesion and therefore the top and bottom closure seals along those areas are readily broken, permitting the hinge or suitcase style opening action shown in FIGURE 4 to commence. As the outward pulling of the end Wall portion 13 continues, the overlapping parts of the wider sections of

end flaps

12a and 12b (one of which is shown as 1241 in FIGURE 4) are torn loose of their adhesive attachment with the side flaps 1th: and 10b and the

flaps

12a and 12b are ripped along lines interconnecting the inner end of the

slots

22 and 23 with the

scores

14 and 15, respectively. Thus, in the opened condition shown in FIGURE 4, the only connection existing between the two trays is the hinge line formed across end wall 12 approximately in the center thereof. If it is desired to employ the trays in the display of product in the retail establishment, the hinge line mentioned above can be cut so as to separate the trays comprising the container. Price marking of the individual cartons can be accomplished while the product is maintained in its packed condition within the confines of the tray portion, whether the device is ultimately to serve as a tray or not.

As indicated previously, the placement of the closure side flaps interiorly of the end flaps results in a substantially uniform clamping action exerted on the layers of packages between opposed side flaps 10a and 10b or side flaps 11a and 1117, as the case may be, both before and subsequent to the opening operation described. During the opening operation, as the one tray (comprising side wall 11, its associated side flaps 11a and 11b, end wall portion 13 and the associated end flaps 13"a and 13"b, the half of end wall 12 adjacent score line 18 and the adhered wider sections of end flaps 121a and 12b) is pivoted outwardly the uniform clamping pressure retains the layer or layers of packages contained therein in place and prevents the disruption which otherwise would occur. This same clamping action also retains the layer or layers of packages in place in the other tray so that no reorganization of the packages is necessary following opening.

Many modifications of the above invention may be used and it is not intended to limit it to the particular embodiment shown and described. The terms used in describing the invention are used in their descriptive sense and not as terms of limitation, it being intended that all equivalents thereof be included in the scope of the appended claims:

What is claimed is:

1. An easy opening tray-forming container having in combination (A) two pairs of marginally connected and alternating end Walls and side walls, and bottom and top closures, said side walls having a Width which substantially exceeds the width of said end walls, the

widths of said side walls being substantially identical and the widths of said end walls being identical whereby said container is rectangular in cross section;

(B) the ends of the blank forming said container lying within the confines of one of said end walls and thereby dividing said one end Wall into two portions, each of which has a pair of oppositely disposed end flaps connected therewith, the end flaps extending from the other said end wall being slotted in the central portion thereof;

\lC) means securing the two end wall portions in juxtaposed position with the distal ends thereof adjacent one another to thereby form said one end wall;

(D) a plurality of layers of packages in said container, said layers being substantially parallel to the planes of said side walls, an interface of adjacent layers of packages occurring along a plane substantially centered between said side walls; and

(E) each of said closures comprising substantially rectangular and full width side flaps hinged to and extending from the said side walls, respectively, said side flaps having a dimension from hinge line to free edge which is equal to about one-half the width of an end wall and being inwardly folded toward one another so that the free edges thereof come into substantially abutting relationship in the same plane, and similarly dimensioned rectangular end flaps hinged to and extending from the end walls, respectively, inwardly folded and secured in overlapping relationship with said side flaps.

2. The container of claim 1 in which said means to secure the two end wall portions comprises a tape.

3. The container of claim 2 in which said tape extends full length of the ends of said blank.

4. The container of claim 3 in which said tape is provided with an integrally formed full length tear strip.

5. The container of claim 1 in which the widths of said end wall portions are unequal.

6. The container of claim 5 in which a pair of opposed side flaps are provided with areas treated to resist firm adhesion thereto, said pair of opposed side flaps being articulated from the side panel connected to the narrower of said end wall portions, one of said areas being located on each of said pair of opposed side flaps at the free edge corner thereof adjacent said narrower end wall portion.

References Cited UNITED STATES PATENTS 2,955,734 10/1960 Barton 229-Sl 3,097,784 7/1963 Schaus 2295l 3,167,237 1/1965 Negus et al 22951 DONALD F. NORTON, Primary Examiner.

R. PESHOCK, Assistant Examiner.

Claims

1. AN EASY OPENING TRAY-FORMING CONTAINER HAVING IN COMBINATION: (A) TWO PAIRS OF MARGINALLY CONNECTED AND ALTERNATING END WALLS AND SIDE WALLS, AND BOTTOM AND TOP CLOSURES, SAID SIDE WALLS HAVING A WIDTH WHICH SUBSTANTIALLY EXCEEDS THE WIDTH OF SAID END WALLS, THE WIDTHS OF SAID SIDE WALLS BEING SUBSTANTIALLY IDENTICAL AND THE WIDTHS OF SAID END WALLS BEING IDENTICAL WHEREBY SAID CONTAINER IS RECTANGULAR IN CROSS SECTION; (B) THE ENDS OF THE BLANK FORMING SAID CONTAINER LYING WITHIN THE CONFINES OF ONE OF SAID END WALLS AND THEREBY DIVIDING SAID ONE END WALL INTO TWO PORTIONS, EACH OF WHICH HAS A PAIR OF OPPOSITELY DISPOSED END FLAPS CONNECTED THEREWITH, THE ENDS FLAPS EXTENDING FROM THE OTHER SAID END WALL BEING SLOTTED IN THE CENTRAL PORTION THEREOF; (C) MEANS SECURING THE TWO END WALL PORTIONS IN JUXTAPOSED POSITION WITH THE DISTAL ENDS THEREOF ADJACENT ONE ANOTHER TO THEREBY FROM SAID ONE END WALL; (D) A PLURALITY OF LAYERS OF PACKAGES IN SAID CONTAINER, SAID LAYERS BEING SUBSTANTIALLY PARALLEL TO THE PLANES OF SAID SIDE WALLS, AN INTERFACE OF ADJACENT LAYERS OF PACKAGES OCCURING ALONG A PLANE SUBSTANTIALLY CENTERED BETWEEN SAID SIDE WALLS; AND (E) EACH OF SAID CLOSURES COMPRISING SUBSTANTIALLY RECTANGULAR AND FULL WIDTH SIDE FLAPS HINGED TO AND EXTENDING FROM THE SAID SIDE WALLS, RESPECTIVELY, SAID SIDE FLAPS HAVING A DIMENSION FROM HINGE LINE TO FREE EDGE WHICH IS EQUAL TO ABOUT ONE-HALF THE WIDTH OF AN END WALL AND BEING INWARDLY FOLDED TOWARD ONE ANOTHER SO THE FREE EDGES THEREOF COME INTO SUBSTANTIALLY ABUTTING RELATIONSHIP IN THE SAME PLANE, AND SIMILARLY DIMENSIONED RECTANGULAR END FLAPS HINGED TO AND EXTENDING FROM THE END WALLS, RESPECTIVELY, INWARDLY FOLDED AND SECURED IN OVERLAPPING RELATIONSHIP WITH SAID SIDE FLAPS.