US3120335A

US3120335A - Container with infolded bottom closure

Info

Publication number: US3120335A
Application number: US136505A
Authority: US
Inventors: Harry B Egleston; Charles Z Monroe
Original assignee: Ex-Cell-O Corp
Current assignee: Ex-Cell-O Corp
Priority date: 1961-09-07
Filing date: 1961-09-07
Publication date: 1964-02-04
Anticipated expiration: 1981-02-04
Also published as: BE567723A

Description

Feb- 4, 1964 H. B. EGLEsToN ETAL 3,120,335

CONTAINER wTTH TNFOLDED BOTTOM cLosuRE 4 Sheets-Sheet l Filed Sept. 7, 1961 Feb. 4, 1964 H. B. EGLEsToN ETAL 3,120,335

CONTAINER WITH INFOLDED BOTTOM CLOSURE Filed Sept. 7, 1961 4 Sheets-Sheet 2 Feb. 4, 1964 H. B. EGLEsToN ETAL 3,120,335

` CONTAINER WITH INFOLDED BOTTOM cLOsURE Filed Sept. '7, 1961 4 Sheets-Sheet 3 INVENTORS CMR/.5 Z MoN/Q05 w #44, 4MM am @WW ATTORNEYS Feb. 4, 1964 H. B. EGLEsToN ETAL 3,120,335

CONTAINER WITH INFOLDED BOTTOM CLOSURE 4 Sheets-Sheet 4 Filed Sept. 7, 1961 United States Patent 3,120,335 CONTAINER WITH INFOLDED BOTTOM CLOSURE Harry B. Egleston, Livonia, and Charles Z. Monroe, Detroit, Mich., assignors to Ex-Cell-O Corporation, Detroit, Mich., a corporation of Michigan Filed Sept. 7, 1961, Ser. No. 136,505 Claims. (Cl. 229-43) The present invention relates to packaging and more specifically to a container bottom closure construction. The invention nds particular, but by no means exclusive, utility in disposable containers adapted for distribution of milk and other dairy products.

This application is a continuation-in-part of our copending U.S. application Serial No. 707,259, filed January 6, 1958, now abandoned.

One form of container of the type just noted and presently in lwide commercial use is disclosed in U.S. Patent No. 2,750,095, issued June 12, 1956, on the application of Carroll R. Alden (Reissue No. 25,021, issued August 8, 1961). Such a container is customarily erected from a iiat blank formed of sheet stock suc-h as paperboard which has 'been cut to shape and impressed with an appropriate pattern of score lines. These lines define a plurality of side panels together with corresponding upper and lower extension aps or closure members.

The usual procedure in erecting the container is to form the blank into a polygonal tube open at both ends and then to close the lower or 'bottom panel extensions, retaining them in place by means of a suitable adhesive. It is presently the practice to coat or impre'gnate the exposed surfaces of the erected tube |by lirnrnersing it in a bath of molten paraffin. Following this operation, the container is cooled to harden the paraiin and is then filled with a selected product such yas milk. The container top is closed and sealed by pressing the closure elements together with heated jaws, thereby yfusing the paraiiin coating so that all cracks are sealed. In order to supplement the strength of the paraffin bond, the top closure elements may be stapled together.

Although paraffin coated containers of the above-described type have been commercially successful, there are certain disadvantages inherent in their use, one of the most marked of which involves the parain coating. In the first place, a suitable dip tank of molten paraffin must be maintained as part of the packaging machinery at the dairy or processing plant. This, along with the extra care and attention required on the part of the operator, plays a part in increasing the cost of the container and finally of the ultimate product. Also, under certain extreme conditions, globules of the parain coating may Hake off of the container walls. While this does not impair the sanitary integrity of the contents, it does tend to impair consumer acceptance of the container.

It has now been discovered that paperboard of the quality heretofore used for dairy product containers can be economically coated with heat and pressure sensitive thermoplastic substances. The thermoplastic substance used is desirably one which is inert to the substances to be packaged, is strong and durable, is inexpensive, and is easy to apply in sheet form onto the paperboard. A coating of' this sort renders the paper sheet material resistant to fluids which would be packaged in the container including such acidic products as milk. One example of such a thermoplastic substance which is useful for packaging dairy products is polyethylene. It will be apparent to those skilled in the art, however, that other thermoplastic materials, such as polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride and acetate copolymer, and polypropylene, to name only a few, will find use under favorable circumstances.

'3,120,335 Patented Feb. 4, 1964 ICC Paper sheet stock for forming containers is initially supplied in the form of rolls, and as the stock is produced it can be coated on both sides with a layer of polyethylene thermoplastic material. One method of accomplishing this is by heating and stretching the polyethylene and applying it when hot directly onto the surface of the paper to which it becomes tightly bonded. The surface of the paper to be used for the outside of the blank is generally coated with a layer approximately 3A of a mil thick while the inside surface of the sheet -is coated with a layer of polyethylene approximately 1 to 11/2 mils thick.

The general aim of the present invention is to provide a new and improved container formed of thermoplastic sheet material, or thermoplastic-coated paperboard sheet material, and which will be strong, simple to erect, close and seal, and susceptible of high volume economical production for packaging milk and other comestibles.

A more specific object of the present invention is to provide a container of the above type having surfaces of sanitary heat and pressure sensitive thermoplastic material which not only protects the contents of the container against admission of harmful substances but also serves as a sealing adhesive for effecting tight closure and sealing of the container.

Another object of the invention is to provide an improved container of the character set forth and having a bottom closure susceptible of automat-ic closing and sealing to form a strong leak-proof bottom on the container which will remain Huid-tight even under severe conditions of use, such as being dropped on a bottom corner.

Still another object of the invention is to provide a container of the foregoing type and having a bottom closure with at least three plies of integrally connected stock at each bottom corner area and a minimal length of raw edge exposed to the interior of the container and the contents thereof.

Other objects and advantages of the present invention will become apparent as the following description proceeds, taken in connection with the accompanying drawings, wherein:

FIGURE 1 is a perspective view of an illustrative closed and sealed container embodying the present invention.

FIG. 2 is a layout View of a 'blank from which the container in FIGURE 1 was erected and showing the inside surface thereof.

FIGS. 3, 4, 5 and l6 are fragmentary perspective views illustrating sequentially various steps in forming the bottom closure of the container of FIGURE l.

FIGS. 7, 8, 9 and 10 are fragmentary perspective views similar to FIGS. 3 to 6 but showing another form of container 'bottom closure also embodying the invention.

FIG. 11 is a layout view of the inside face of a blank similar to that shown in FIG. 2 Ibut yadapted to define the bottom closure of FIGS. 7 to '10.

FIG. 12 is an outside ybottom View of the container of FIGURE 1 and showing certain embossing of the latter in accordance with a further aspect of the invention.

FIG. 13 is an outside bottom view similar to FIG. 12 but showing a container having the bottom closure of FIGS. 7 to l0.

FIG. 14 is a view of the inside face of the container bottom of FIG. 13, looking in the direction indicated by the line 14-14 in FIG. 10.

While 'the invention is susceptible of Various modifications and alternative constructions, certain illustrative containers have been shown in the drawings and will be described -below in detail. 4It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed. On the contrary, the inteniton is to cover all modifications, alternative constructions, equivalents and uses falling within the spirit and scope of the invention as expressed in the appended claims.

Referring more specifically to the drawings, there is shown a container (FIG. 1) which represents an illustrative embodiment of the present invention, The container 20 is formed from paper or other suitable sheet material and is self-sustaining in shape. To render the sheet material uiddtight and capable of holding such acidic liquids as milk, the sheet material has surfaces of, or is coated with, a thermoplastic material of the type exemplified by polyethylene.

The container 20 comprises a tubular body 21 which in the present instance happens to be substantially square in cross section. At its base the body 21 is provided with a bottom closure 22. The upper end of the body 21 in this instance terminates in what will be recognized as the familiar gable top type of end closure 23 which is surmounted by a central laminar rib or truss 24. The top end closure has incorporated therein an extensible spout for dispensing the contents of the container.

The container 20 is fashioned from a tlat blank 25 of high-grade paperboard coated with a layer of polyethylene thermoplastic material. By means of an appropriate pattern of score lines the blank 25 (the inner face of which is illustrated in FIG. 2) is divided into a plurality of panels and areas which are utilized for the walls of the container and the closure parts when the container is erected. The central and major area of the blank becomes the body 21 of the container and is defined by spaced apart

transverse score lines

26, 28, running in substantially parallel relation across the face of the blank. Intersecting the

lines

26, 28, at spaced intervals therealong are a series of

perpendicular score lines

29, 30, 31, and 32, which define, in the central and major area of the blank,

side panels

34, 35, 36, and 37 together with a fractional side panel or side seam tlap 38. When the container is erected, the latter is adhesively secured in overlying relation with the inside face of the side panel 34.

It should be noted that the

transverse score lines

26, 28 are not continuous but are formed in staggered portions -interrupted by the

perpendicular score lines

29, 30, 31, and 32. The purpose of this staggered sco-ring is to accommodate the thickness of the paper as it is bent along the score lines when the container is erected and thus prevent crowding of the paper at the various corner junctions of the score lines. This not only enhances the strength and appearance of the iinished container but facilitates its erection and closure by automatic machinery.

Connected to the lower edges of the side panels along the lower transverse score line 28 are bot-

tom closure panels

39, 40, 41, and 42. Accordingly,

alternate side panels

34, 36 have respectively connected therewith opposed

bottom closure panels

39, 41. 'Ihe latter in turn include respectively a tuck-in flap 5t) and an overlying or outside overlap flap 51. The tuck-in flap Sti is relieved or recessed at 52 so that it receives the adjacent end 53 of the side seam tiap when the bottom closure is sealed.

In this manner an extra thickness of sheet material at one edge of the bottom closure is avoided.

Similarly, alternate side panels 3,5, 37 have connected therewith along the transverse score line 28, opposed

triangular infold panels

40, 42, respectively. The infold panel 40 is anked by triangular fold-

back panels

55, 56 connected thereto along converging score lines 5S, S9, starting at the intersections between the perpendicular score lines 29, and the transverse score line 28, converging downwardly and intersecting at the cut lower edge of the blank (as viewed in FIG. 2,). By the same token, infold panel 42 is flanked by fold-back panels 6), 61 connected thereto along

fold lines

62, 63. In addition to the above connections, triangular fold-back panel 56 is connected to bottom panel 39, panel 55 is connected to bottom panel 41, panel 61 is connected to panel 41, while panel 60 is connected to the bottom portion 53 of the side seam ap 38.

Integral with the upper ends of the side panels, but separated therefrom by the transverse score line 26, are a plurality of panel extensions which give the top of the container 2t) its characteristic gable shape. These areas include a transverse score line 66 generally parallel to the score line 26 and spaced between the latter and the top edge of the blank 25. The areas below the line 66 define

roof panels

68, 69 and triangular end and fold-

back panels

75, 78, 79 and 76, `B8, 89 of the top closure. The areas above the line 66 define the parts of the central laminar rib 24, namely, inner rib panels S4, 85, 94, 95,

outer rib panels

70, 71, and sealing

iiaps

72, 73. Again score line 66 is not a straight line but includes staggered portions 66a, 66b, 66e and 66d corresponding respectively to the

panels

34, 35, 36 and 37, for accommodating the thickness of the paper when the container closure is folded.

The blank 25 is transformed into a completed container as illustrated in FIG 1, by iirst folding it upon itself to form a fiat tube and adhesively securing the side seam ap 38 and its

extensions

53, 98, 99 to the inside faces of

panels

39, 34, 78 and 84. While it is possible to utilize the polyethylene coating as an adhesive for the side seam, it may in some instances be feasible to apply an additional amount of adhesive thereto for purposes of forming the side seam. Such added adhesive is desirably resistant to heat at the melting point of the polyethylene or other coating on the container so that the side seam remains tight during subsequent closing and sealing operations. One polyethylene base adhesive used for the side seam has a melting point of about 500 F.

The iiattened blank tube is then erected into a tube of substantially square cross section (FIG. 3) and the bottom closure is completed. Accordingly, the score l-ines or creases 58, 59, 62, and 63 are broken or given a prebend by folding the

triangular infold aps

40, 42 inwardly towards each other (FIG. 4). The tuck-in tiap 5) is then in position for insertion beneath end panel 39 and above the triangular fold-

back aps

56 and 60 so that the bottom panel 39, which includes the sealing iiap 51, overlies end panel 411, which includes the tuck-in ap (as Viewed in FIG. 5).

In order to seal the bottom of the container the bottom closure panels are first broken but before they are finally folded they are subjected to a source of intense heat so as to melt or vat least activate and render adhesively active the coating of polyethylene on both surfaces of the bottom closure panels. When a polyethylene coating is used the heat must be suflicient to partially melt the coating which melts between about 230 and 275 F., depending upon its density. These panels are then folded together and the tuck-in flap 50 is inserted in place. When the bottom closure is completed it is subjected to pressure between cooled pressure pads to cool and solidify the polyethylene plastic adhesive and thus produce a completely sealed bottom end closure.

Provision is made for obtaining an exceptionally tight seal of the bottom closure 22 when finally completed. .VI his is accomplished in large measure by constructing the bottom closure parts so that the cut edges of the triangular foldback pane-

ls

5S, 56, 60 and 61, which abut each other in the completed bottom closure, will enter into positive abutting engagement with each other prior to completion of the bottom closure. In furtherance of such objective, the bottom closure panels 4G and 42 are so proportioned that the combined length of the triangullar fold-back panels 55, S6, as well as the combined length of the triangular fold-

back panels

60, 61, normal to the score line 28, will be slightly greater than the base width of each triangular bottom closure panel measured along the score line 2S (IFIG. 2). Stated another way, and in the present instance, the bottom closure panels are proportioned so that those portions of the

vertical score lines

29, 30, 31 and 32, joining the bottom closure panels 39, 4i), 41 and 42, and defining a side of each of the triangular foldback panels, are slighlty longer than one-half the width of each triangular bottom closure panel measured along the score line 28. Thus, as the bottom closure panels are folded infto engagement and approach the position illustrated in PIG. 5, the cut edges of thc triangular fold-

back panels

55, 56, 6!) and 61 will enter into positive abutting engagement with each other. With further downfolding of the bottom closure panels from the position of `FIG. 5 to the fully downfolded position shown in FIG. 6, and the application of sealing pressure thereto in the latter position, the paperboard is crowded together under substantial compression in its own plane las well as transversely thereof. tThe tightness of the ultimate bottom seal is thus materially increased.

When the container has been erected and the bottom closure sealed, it is normally in a sanitary condition. In some instances, however, it may be subjected to iurther sterilization as by irradiation with ultraviolet light or by dipping in a tank of water at approximately 200 F The sterilized containers are then filled with the desired product.

To seal the container top closure, the parts thereof are iniolded into gable form. During the course of such action the triangular

panel crease lines

86, 81, 90, 9'1 are broken by infolding the

triangular end panels

75, 76 toward each other. The inner and outer rib panels and Sealing

liaps

72, 73 are then heated on both sides, as was done with the bottom flaps, to adhesively activate the polyethylene thermoplastic coating. The container is then closed `as by passing its top portion between a pair of converging shoes which bring the adhesively activated rib panels and sealing flaps together to complete the gable top structure. The rib panels and sealing iiaps are thereupon subjected to substantial sealing pressure which may be derived from cooled pressure jaws leaving the top closure in sealed condition as illustrated in FIG. 1. The top closure seal may, of course, be broken by `the user through deliberate application of external forces to effect partial disassembly of the top rib 24 and expose the pouring spout housed therein.

l.For the purpose of further enhancing the fluid-tight integrity and the durability of the seal in both the bottom and top closures of the container 20, an additional precaution may be taken, particularly where the container is used for packaging fluids. This. involves the application of increased pressure to selected areas of the closure parts during the pressure sealing operation, producing indentations or embossments in the closure plies which effectively close up incipient fluid escape channels. In the present instance, these areas of increased pressure or ernbossing on'the bottom closure are represented by the crosshatched areas in FIG. 12.

AReferring more specifically to IFIG. 12, the outside bottom View of the container 2t) is there shown. Rectangular embossed area 105 on overlying or outside bottom panel 39 has been pressed inwardly forl almost the thickness of one ply of stock. This effectively blocks the incipicnt leakage channels which would otherwise occur along the free-cut edge of the bottom tuck-in flap 5? and the side seam lflap 53. Embossrnents 106, which in this instance happen to be circular, are located primarily on the overlying or outside bottom panel 39 and are adapted to block oi channels at the abutting edges of

bottom foldback panels

55, 56, 60, 61. In addition, the embossments 106 enhance the sealing between the bottom fold-back panels and the flaps `5t?, 51, 53, on the one hand, and between the bottom fold-back panels and the

bottom infold panels

40, 42, on the other hand. Similarly, embossments 108, which.v happen to be wedge-shaped, are situated adjacent the lateral edges of the overlying bottom flap 51` and close the incipient channels between the underlying abutting plies of the bottom tuck-in flap 56, side seam ap 53, and the

panels

40', 55, 56, and 42, 60, 61.

The container may have another form of bottom closure 22a dilering in some respects from the bottom closure 22 described above but also embodying the present invention. Turning now to FIGS. 7 to 11, inclusive, 13 and 14, wherein like reference numenals designate like parts described earlier herein, it lwill be noted that rthe bottom clos-ure 22a bears considerable similarity to the bottoni closure 22.

In this instance, the container 20 is formed from a flat blank 110, the inside face of which is shown in IFIG. 11, having many parts in common with the blank 25 shown in FIG. 2 and already described herein. The blank thus includes

transverse score lines

26, 28, 66,

perpendicular score lines

29, 30, 31 and 32,

side panels

34, 35, 36, 37, and side seam ilap 38. Above the score line 26, the blank includes a series of top closure elements which in this instance happen to be similar to those of the blank 25. Below the score line 28, the blank 110 includes triangular bottom closure panel 40 ilanked by triangular fold-

back panels

55, 56, all constituting an eX- tension of the side panel 35, and triangular bottom closure panel 42 and fold-

back panels

60, 61, all being an extension of side panel 37. Alternating with the

panels

40 and 42, are major bottom closure panel l'111, constituting an extension of the side panel 34, and bottom closure panel 112, constituting an extension of the side panel 36. In addition, there is panel extension 114 of the side seam flap 38.

In the bottom closure 22a, the major bottom panels '111, 112 fold relative to one another in a relationship which is just the opposite from that of their counterparts 39 and l41 in the closure 22. Thus, the free-cut marginal edge portion of panel 111 has defined thereon a tuck-in iiap 2115, while the free-cut marginal edge portion of the panel 112 has defined thereon an overlying or outside overlap iiapl 116. The ends of the tuck-in flap are chamfered or tapered as at 118 to facilitate entry of the ap 115 between the triangular fold-

back panels

55, 61 and the inside face of the overlying flap `11'6 of bottom panel v112. In addition?, the end of Ithe side seam panel extension 114 is relieved or chamfered as at 119, while the end portion of the overlying lflap 116 which faces it is also relieved or chamfered at 120.

Completion of the formation of the bottom closure 22a is similar to that of the closure 22 and is illustrated sequentially :in FIGS. 7, 8, `9 and l0. Starting with the blank v11i) in open-ended tubular lforfrn, illustrated in FIG. 7, the triangular bottom panels liti, 42 and their associated lfold-

back panels

55, 56, `60, 61, as Well as major bottom panels 111, 112 are first broken inwardly and downwardly, as illustrated in FIG. 8. They are then subjected to `fairly intense heat, as mentioned earlier herein, so as to render a-dhesively lactive the plastic material, such as polyethylene, on both surfaces of the bottom closure panels. The iniolding o-r downiolding is then contin-ued rapidly, the tuck-in -flap 115 being rst slid beneath the inside lface of the overlying ap 116 and thereupon inserted between the inside face of the overlying botto-m panelv 112 and adjacent triangular |fold-

back panels

55, 61. Prior to the completion of the downfolding, with the bottom closure in the 4condition illustrated in FIG. 9', the ap 116 substantially overlies the tuck-in flap 115. Due to the fact that the triangular fold-

back panels

55, 56, '60, 61 are constructed with the same length-to-side panel-width relationship described in connection with the bottom yclosure 22, the ends of the fold-back panels enter into positive abutting engagement prior to completion of downioldin-g. The -downfolding conti-nues with crowding of paperboard stock at the abutting cut ends of the Ifol-dback panels, until the bottom closure y22a has reached the :condition illustrated in JFIG. 10l at which time the ultitmate seal is completed.

For the purpose of further enhancing the seal of the bottom closure 22a and eliminating incipient leakage channels Iwhich might otherwise occur, resort may be had to a plurality of concentrated pressure areas defining blocking embossments similar to those described above in connection with the bottom closure 22. Accordingly, it will be noted upon reference to FIG. 13, which is an outside view of the bottom `closure 22a, that the same includes a relatively large rectangular embossment 121 (shown in dot-dash outline) covering the overlying or outside bottom lap 112 except the area thereof overlying the tuckin flap. By the same token, the inner major bottom panel 111 is embossed over a rectangular area 122 extending from the side seam panel to the edge of the overlying ilap 115. In addition, spot embossments 124 (FIGS. 13 and 14), which in this instance happen to be of circular shape with narrow rectangular central indentations, block incipient leakage channels adjacent the free-cut edge of the tuck-in ap, and also adjacent the inside free-cut edge and the chamfered end 119 of the side seam panel extension 114. lCertain of these incipient leakage channels run between the outer perimeter of the container and the central portion of the free cut edge of the bottom closure panel 115 which is exposed to the interior of the container. Another such incipient leakage channel runs from the exposed portion of the edge of the side seam panel extension 114 inside the container, along such edge and the end of the side seam panel extension, to the outer perimeter of the container (FIGS. 13 and 14). By reason of the

chamfers

119, 120 and the selective distribution of sealing pressure upon the bottom closure 22a, the overlapping plies of the side seam extension 114 and the inside panel 11-1, as wel las the overlapping plies of the tuckin flap 115 and overlying flap 116 become substantially coplanar, eliminating objectionable bulges on the outer surface of the bottom closure.

We claim as our invention:

l. A container of paperboard or the like having an overall surface of thermoplastic material that becomes adhesive when subjected to heat, said container comprising, in combination, a tubular body, a top closure overlying said body, tirst and second pairs of opposed bottom closure panels connected to said body, said second pair of bottom closure panels being triangular in shape and infolded ybetween said body `and said first pair of bottom closure panels, two pairs of triangular Ifold-back panels each pair of which is connected to a respective one of said triangular bottom panels and to respective ones of said first pair of opposed bottom closure panels, said foldback panels also having cut edges and being folded against the inside surface of said first pair of opposed bottom panels, the combined length of said fold-back panels along said opposed bottom panels of said tirst pair being greater than the length of the base of the adjoining triangular bottom panel whereby said fold-back panels are crowded together along their cut edges upon infolding and sealing of said bottom closure panels.

2. A container of paperboard or the like having a surface of thermoplastic material that becomes activated adhesively when subjected to heat, said container comprising, in combination, a tubular body, a top closure overlying said body, a first pair of opposed bottom closure panels connected to said body, a second pair of opposed bottom closure panels also connected to said body, said second pair of bottom closure panels being triangular in shape and infolded between said body and said rst pair of bottom closure panels, two pairs of triangular fold-back panels each pair of which is connected to a respective one of said triangular bottom panels and to respective ones of said iirst pair of opposed bottom closure panels, said fold-back panels also having cut edges and being folded against the inside surface of said first pair of opposed bottom panels and with adjacent edges of each said pair of yfold-back panels abutting each other, the combined length of said fold-back panels along said opposed bottom panels of said first pair being greater than the length of the base of the adjoining7 triangular bottom panel whereby said fold-back panels are abuttingly crowded together along their cut edges upon infolding and sealing of said bottom closure panels, and an overlying ilap integral with one of said rst pair of bottom closure panels and adapted to extend over the other bottom closure panel in said lirst pair beyond the abutting edges of said foldback panels.

3. A container of paperboard or the like having an overall surface of thermoplastic material that becomes activated adhesively when subjected to heat, said container comprising, in combination, a body, a top closure on said body, iirst and second pairs of opposed bottom closure panels connected to said body, said second pair of bottom closure panels being triangular in shape and in- -folded between said body and said first pair of bottom closure panels, two pairs of triangular fold-back panels each pair of which is connected to a respective one of said triangular bottom panels and to respective ones of said iirst pair of opposed bottom closure panels, said fold-back panels also having cut edges and being folded against the inside surface of said iirst pair of opposed bottom closure panels and with adjacent cut edges of each said pair of fold-back panels abutting each other, the combined length of said `fold-back panels along each said opposed bottom closure panel of said rst pair being greater than the length of the base of the adjoining triangular bottom panel whereby said abutting cut edges of said fold-back panels are crowded together upon infolding and sealing ot said bottom panels, a tuck-in flap integral with one of said rst pair of bottom closure panels and inserted between the other bottom closure panel or said first pair and the fold-back panels thereagainst, and an overlying flap integral with and extending over the other one of said first -pair of bottom closure panels, said overlying flap extending over and beyond said tuck-in flap.

4. A container of paperboard or the like having an overall surface lof thermoplastic material that becomes activated adhesively when subjected to heat, said container comprising the combination of a tubular body having a side seam flap, a top closure on said body, iirst and second pairs of opposed bottom closure panels connected to said body, a side seam panel extension secured to one of said tirst pair of bottom closure panels, a relieved end portion on said side seam panel extension, said second pair of bottom closure panels being triangular in shape and infolded between said body and said irst pair of bottom closure panels, two pairs of triangular fold-back panels each pair of which is connected to a respective one of said triangular bottom panels and to respective ones of said tirst pair of opposed bottom closure panels, said fold-back panels being folded against the inside surface of said first pair of opposed bottom panels and with adjacent edges of each said pair of fold-back panels abutting each other tightly throughout their entire length, and an overlying fiap integral with the other one of said iirst pair of bottom closure panels, said overlying ilap being constructed and arranged to extend over the first one of said first pair of bottom closure panels and beyond the abutting edges of said fold-back panels to effect a thermoplastically scaled margin between said abutting edges and the exterior of said container, said overlying lflap having a relieved portion substantially complemental to said relieved end portion of said side seam panel extension.

5. A blank for a container of foldable sheet material having an overall surface of thermoplastic material that becomes adhesive when subjected to heat, said blank comprising, in combination, a plurality of side panels, a plurality of top closure panels, first and second pairs of bottom closure panels alternately connected to said side panels as extensions thereof, said second pair of bottom closure panels being triangular in shape, two pairs of triangular fold-back panels each pair of which is connected to a respective one of said triangular bottom panels and to respective ones of said first pair of opposed bottem closure panels, each said pair of told-back panels having a common free cut edge, the combined length of said fold-back panels along said bottom closure panels of said lirst pair being greater than the length of the base of the adjoining triangular bottom panel whereby said fold-back panels are adapted to be crowded together along their free cut edges upon infolding and sealing yof said bottom closure panels.

6. A container of paperboard or the like having an overall surface of thermoplastic material that becomes activated adhesively when subjected to heat, said container comprising the combination of a tubular body, a top closure Ioverlying said body, iirst and second pairs of overlapping opposed bottom closure panels connected to said body, said second pair of bottom closure panels being tliangular in shape and infolded between said body and said iirst pair of bottom `closure panels, two pairs of triangular told-back panels each pair of which is connected to a respective one of said triangular bottom panels, said fold-back panels being folded against the inside surface of said rst pair of opposed `bottom panels and With adjacent edges of each said pair of fold-back panels abutting each other, an overlap iiap integral with one of said iirst pair of bottom closure panels, the other bottom closure panel of said `first pair having an overlapped edge with its central portion exposed to the interior of the container, said overlap flap being constructed and arranged to extend over the other bottom closure panel of said first pair and beyond the abutting edges of said fold-back panels, and means defining blocking indentations in at least said one of said iirst pair of bottom closure panels adjacent said overlapped edge of said other bottom closure panel between the central portion of said edge and the outer perimeter of said container, whereby incipient leakage channels are blocked and the iiuidtight integrity of said container is maintained.

7. A container of paperboard or the like having an overall surface lof thermoplastic material adapted to become activated adhesively when subjected to heat, said container comprising, in combination, a tubular body, a top closure on said body, iirst and second pairs of overlapping opposed bottom closure panels connected to said body, a side seam panel extension secured to one of said irst pair of bottom closure panels, said side seam panel extension having an end portion and an inner edge, said inner edge having a portion exposed to the inte-rior of the container, said second pair of bottom closure panels being triangular in shape and infolded between said body and said rst pair of bottom closure panels, two pairs of triangular fold-back panels each pair of which is connected to a respective one of said triangular bottom panels, said fold-back panels being folded :against the inside surface of said iirst pair of opposed bottom panels and with adjacent edges of each said pair of fold-back panels abutting each other, the other bottom closure panel of said rst pair having an overlapped edge with its central portion exposed to the interior of the container, indentations in at least said one of said means defining blocking rst pair of overlapping opposed bottom closure panels adjacent said overlapped edge between the central portion thereof and the outer perimeter of the container, and means deiining blocking indentations in at lea-st one of said first pair of bottom closure panels between said exposed portion of said inner edge oi said side seam panel extension and the outer perimeter of said container.

8. A container of oldable sheet material having a thermoplastic surface that becomes activated adhesively when subjected to heat, said container comprisin in combination, a body, a top closure on said body, iirst and second pairs of opposed bottom closure panels connected to said body, a side seam panel extension secured to one of said tirst pair of bottom closure panels and having an inner edge and a projecting end, said second pair of bottom closure panels lbeing triangular in shape and infolded between said body and said iirst pair of bottom `closure panels, two pairs of triangular fold-back panels each pair of which is connected to a respective one of said triangular bottom panels, said fold-back panels being lfolded against t-he inside surface of said irst pair of opposed bottom closure panels and with adjacent edges of each said pair of fold-back panels abutting each other, a tuck-in iiap integral with one of said iirst pair of bottom closure panels and inserted between the other bottom closure panel of said rst pair land the fold-back panels thereagainst, said tuck-in flap having an overlapped edge, an overlap flap integral with and extending over the other one of said iirst pair of bottom closure panels, said overlap iiap extending over and beyond Isaid tuck-in iiap, said overlap iiap having a relieved portion substantially complemental to said projecting end of said side seam panel extension, and means defining blocking indentations in said rst pair of bottom closure panels at the overlapped edge of said tuck-in flap and at said inner edge and projecting end of said side seam panel extension.

9. A blank for a container as defined in claim 5, having an overlapping flap integral with one of said iirst pair of bottom closure panels.

10. A blank for a container `as defined in claim 5, having a tuck-in ap integral with one of said iirst pair of bottom closure panels.

References Cited in the tile of this patent UNITED STATES PATENTS 1,924,529 Wellman Aug. 29, 1933 2,189,431 Moore Feb. 6, 1940 2,324,757 Bedey July 20, 1943 2,362,862 Sidebotham Nov. `14, 1944 2,461,251 Ball lFeb. 8, 1949 2,501,852 Ringler Mar. 28, 1950 FOREIGN PATENTS 676,531 Great Britain July 30, 1952 UNITED STATES PATENT OFFICE CERTIFICATE 0E CORRECTION Patent Noo 3y 120335 February 4V 1964 Harry Bo Egleston et al.7

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should resid as Corrected below.

Column 9q line 52 after "Container," insert means defining blocking line 53 strike out "means definingm; line 54, strike out "blocking"a Signed and sealed. this 23rd day of June 1964e (SEAL) Attest:

ERNEST WQ SWIDER EDWARD J. BRENNER Atesting Officer Commissioner of Patents

Claims

1. A CONTAINER OF PAPERBOARD OR THE LIKE HAVING AN OVERALL SURFACE OF THERMOPLASTIC MATERIAL THAT BECOMES ADHESIVE WHEN SUBJECTED TO HEAT, SAID CONTAINER COMPRISING, IN COMBINATION, A TUBULAR BODY, A TOP CLOSURE OVERLYING SAID BODY, FIRST AND SECOND PAIRS OF OPPOSED BOTTOM CLOSURE PANELS CONNECTED TO SAID BODY, SAID SECOND PAIR OF BOTTOM CLOSURE PANELS BEING TRIANGULAR IN SHAPE AND INFOLDED BETWEEN SAID BODY AND SAID FIRST PAIR OF BOTTOM CLOSURE PANELS, TWO PAIRS OF TRIANGULAR FOLD-BACK PANELS EACH PAIR OF WHICH IS CONNECTED TO A RESPECTIVE ONE OF SAID TRIANGULAR BOTTOM PANELS AND TO RESPECTIVE ONES OF SAID FIRST PAIR OF OPPOSED BOTTOM CLOSURE PANELS, SAID FOLDBACK PANELS ALSO HAVING CUT EDGES AND BEING FOLDED AGAINST THE INSIDE SURFACE OF SAID FIRST PAIR OF OPPOSED BOTTOM PANELS, THE COMBINED LENGTH OF SAID FOLD-BACK PANELS ALONG SAID OPPOSED BOTTOM PANELS OF SAID FIRST PAIR BEING GREATER THAN THE LENGTH OF THE BASE OF THE ADJOINING TRIANGULAR BOTTOM PANEL WHEREBY SAID FOLD-BACK PANELS ARE CROWDED TOGETHER ALONG THEIR CUT EDGES UPON INFOLDING AND SEALING OF SAID BOTTOM CLOSURE PANELS.