Hermetically sealed carton

In accordance with the present invention a paperboard container is provided with a hermetic end closure. The manufacturers flap, which is of unique construction, is foldably connected to an adjacent ungussetted panel. During the folding sequence, the manufacturers flap is sealed to a gussetted panel and the gussets at either end of the container are then caused to be moved outwardly to form projecting wings, and then the inner surfaces of the rib panels are brought into juxtaposed alignment for sealing engagement to form a continuous and uninterrupted hermetic closure.

BACKGROUND OF THE INVENTION 
This invention relates to paperboard containers in general, and in 
particular to an improved hermetic closure for paperboard containers. 
Paperboard containers are now being used to package a wide variety of 
organic products, especially processed foods. These containers must be 
siftproof, stackable, and resistant to air, liquids, and insect 
infestation. Packages which are to be sold in supermarkets should also be 
sturdy and pilfer-proof, and have a relatively long shelf life. 
The packages most commonly used to meet these requirements have been 
multi-layer containers consisting of a paperboard box and a flexible sheet 
of hermetically sealable material. The flexible sheet has been used either 
as a liner for the box, as in French Pat. No. 1,247,747, or as an overwrap 
for it. Single-layer coated paperboard containers, though less expensive 
and easier to manufacture, are seldom seen outside the dairy case due to 
the difficulty of making a closure which is both hermetic and flat enough 
to be stackable. 
It is therefore an object of the present invention to provide a hermetic 
closure for a paperboard container. 
It is another object of the present invention to provide a novel low-cost 
paperboard container which is sift-proof, pilfer-proof, air resistant, 
durable and resistant to infestation by insects. 
It is yet another object of the present invention to provide a paperboard 
container with a long shelf life and superior stacking strength.

SUMMARY OF THE INVENTION 
In accordance with the present invention a paperboard container is provided 
with a hermetic end closure. The manufacturers flap, which is of unique 
construction, is foldably connected to an adjacent ungussetted panel. 
During the folding sequence, the manufacturers flap is sealed to a 
gussetted panel and the gussets at either end of the container are then 
caused to be moved outwardly to form projecting wings, and then the inner 
surfaces of the rib panels are brought into juxtaposed alignment for 
sealing engagement to form a continuous and uninterrupted hermetic 
closure. 
DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawings, wherein like reference characters designate 
like parts throughout the several views, there is shown in FIG. 1A a prior 
art blank for a container having gable-top clsoures at both ends. Since 
the two end closures are identical, only one will be described in detail; 
the description applying equally to either end. The blank, 100a, is 
vertically divided by score lines 202, 203, 204a, 201a, into four side 
panels 120, 130, 140, 110, alternately gussetted and ungussetted, and a 
manufacturers flap 160. Each of these five panels is further divided by 
horizontal score lines 205 and 206 into the familiar body, roof, and rib 
sections of a gable-top blank. Thus, gussetted panel 110 consists of a 
body panel 111, a roof section consisting of triangular end panel 112 
attached to a triangular foldout panels 113 and 114 along diagonal score 
lines 208 and 209, and a rib section comprising rib panels 115 and 116 
joined along short vertical score line 210. Similarly, gussetted panel 130 
consists of a body panel 131, a triangular end panel 132 joined to 
triangular foldout panels 133 and 134 along diagonal score lines 211 and 
212, and rib panels 135 and 136 joined along score line 213. Ungussetted 
panel 120 consists of body panel 121, roof panel 122, and rib panel 123, 
while ungussetted panel 140 consists of body panel 141, roof panel 142, 
and rib panel 143. In much the same manner, the manufacturers flap 160 
consists of a side sealing flap 161, a side roof flap 162, and a side rib 
flap 165. 
Before proceeding with a description of the blank of the present invention, 
it should be noted that the conventional practice in the prior art was, 
and still is, to make the manufacturers flap as narrow as possible in 
order to conserve material. Also, the manufacturers flap is almost always 
attached to a gussetted panel so that fewer score lines are required on 
the side roof and rib flaps. This prior art practice is readily seen by 
refering to FIG. 1A, wherein manufacturers flap 160 is depicted as being 
relatively narrow with respect to panels 110 and 130. 
FIG. 1 depicts a container blank 100 modified in accordance with the 
present invention. Since the two end closures are identical, only one end 
thereof will be described in detail, it being understood that the 
description applies equally to either end. 
Gussetted panel 110 consists of first body panel 111 and attached thereto 
along horizontal score line 205 is a roof section consisting of first 
triangular end panel 112 attached to a first pair of triangular fold-out 
panels 113 and 114 along diagonal score lines 208 and 209. Surmounting 
panels 113 and 114, and extending therefrom along horizontal score line 
206, are first and second rib panels 115 and 116, respectively, which are 
joined together along vertical fold line 210. 
Gussetted panel 110 is foldably connected to ungussetted panel 120 along 
vertical score line 201. Panel 120 consists of second body panel 121 which 
is connected to a first roof panel 122 along horizontal score line 205. 
Roof panel 122 is connected to third rib panel 123 along horizontal score 
line 206. 
Gussetted panel 130 is foldably connected to ungussetted panel 120 along 
vertical score line 202. Panel 130 consists of third body panel 131 and 
attached thereto along horizontal score line 205 is a roof section 
consisting of second triangular end panel 132 attached to a second pair of 
triangular fold-out panels 133 and 134 along diagonal score lines 211 and 
212. Surmounting panels 133 and 134, and extending therefrom along 
horizontal score line 206, are fourth and fifth rib panels 135 and 136, 
respectively, which are joined together along vertical fold line 213. 
Ungussetted panel 140 is foldably connected along vertical score line 203 
to panel 130. Panel 140 consists of a fourth body panel 141 and foldably 
connected thereto along horizontal score 205 is a second roof panel 142. 
Roof panel 142 is foldably connected to sixth rib panel 143 along 
horizontal score line 206. 
Manufacturers flap 150 is foldably connected to ungussetted panel 140 along 
vertical fold line 204. Flap 150 consists of side sealing flap 151 which 
is foldably connected to a side roof flap, consisting of triangular end 
panel 152 and triangular foldout panel 153 joined along diagonal score 
line 214. Side rib panel 155, which is the seventh rib panel, is foldably 
connected to panel 153 along horizontal score line 206. 
In accordance with the present invention, manufacturers flap 150, as shown 
in FIG. 1, is foldably connected to ungussetted panel 140 along score line 
204. The width of seventh rib panel 155 is substantially equal to one-half 
the width of body panel 131, while side sealing flap 151 has the same 
dimensions as body panel 131. In an alternate embodiment, the width of 
manufacturers flap 150 can be substantially equal to one-half of the width 
of body panel 131, along its entire length, without adversely affecting 
the cartons construction or the ease of folding. When this alternative 
manufacturers flap construction is employed in the asceptic packaging of 
sterile milk, for example, it is preferred to skive the manufacturers flap 
in accordance with Haas et al., U.S. Pat. No. 3,495,507. It is apparent, 
that the dimensions of side rib panel 155 would be unaffected by halving 
the width of the manufacturers flap 150. It is the placement of the 
manufacturers flap and the dimensions of its side rib flap, which when 
combined with the folding sequence hereinafter described, serve to produce 
the improved hermetic seal of the subject invention. 
Blank 100 also differs from blank 100a in that the former has an additional 
panel, cover panel 124, attached along horizontal score line 207 to a rib 
panel selected from the group consisting of third rib panel 123 and sixth 
rib panel 143. In the illustrated embodiment, the cover panel 124 is 
attached to rib panel 123. Alternatively, cover panel 124 could be 
selected for attachment to rib panel 143 without affecting the invention. 
As will be shown later, the cover panel provides a flat, attractive 
closure, and greatly increases the stacking strength of the finished 
container. 
FIGS. 2 and 2A show the partially assembled boxes formed in the first step 
of the folding sequence from the blank of FIGS. 1 and 1A, respectively. In 
FIG. 2A, blank 100a is folded along score lines 201a, 202, 203, 204a to 
form a tube, with the outer surface of manufacturers flap 160 being 
heat-sealed to the inner surface of ungussetted panel 120. 
In FIG. 2, blank 100 is folded along score lines 201, 202, 203, 204 to form 
a substantially rectangular tube, and the outer surface of manufacturers 
flap 150 is heat-sealed to the inner surface of gussetted panel 110. 
FIG. 3 is an interior view of the tube, taken along the line 3--3 in FIG. 
2, which shows more clearly the placement of manufacturers flap 150. As is 
indicated in FIG. 3, side sealing flap 151 completely overlies body panel 
111, so that the free edge of flap 151 lies in the score line 201. Panels 
152 and 153 overlie panels 112 and 113, respectively, but as shown in FIG. 
3, the preferred embodiment, triangular end panel 152 is slightly smaller 
than triangular end panel 112, which it overlies, so that score line 209 
is not covered. This facilitates folding during later stages of the 
sequence. Since the width of seventh rib panel 155, is slightly greater 
than first rib panel 115, it completely covers rib panel 115 and the free 
edge of 155 lies in score line 210. 
FIG. 4A shows the second stage in the prior art folding sequence. Rib 
panels 115 and 116 are pinched together and outward along line 210, while 
rib panels 135 and 136 are pinched outward along line 213. Roof panels 122 
and 142 are folded in along score line 205 to form a roof for the 
container. Triangular end panel 112 extends out beyond the side of the 
box, and panels 113 and 114 fold down along score lines 208 and 209 to 
overlie it, forming a projecting wing. In like manner, panels 132, 133 and 
134 form a projecting wing with edges defined by lines 211 and 212. 
Finally rib panels 123 and 143, 115 and 116, 135 and 136 are juxtaposed in 
paired relationship and heat-sealed together to form an upstanding rib. 
FIG. 5A shows the disposition of the manufacturers flap after the second 
step in the folding sequence. Since flap 160 has been affixed to an 
ungussetted panel, the two are folded as one. Side roof flap 162 is 
infolded along with roof panel 122, and side rib flap 165 is trapped 
between panels 123 and 143. 
While bonding of the rib panels is intended to form a continuous hermetic 
closure, an inspection of FIG. 6A reveals that the placement of side rib 
panel 165 creates a gap in the seal. By the application of tremendous heat 
and pressure, panels 123 and 143 can be bonded along their entire lengths, 
but panels 165 will, nonetheless, continue to exert a separating force 
that will eventually cause the seal to rupture. Thus, a closure formed in 
accordance with the prior art has, at best, a brief and uncertain 
duration. The gap in the seal and the attendant problems arising therefrom 
are apparent from a careful examination of French Pat. No. 1,247,747, 
which represents the deficiencies in hermetic closures of the prior art, 
which this invention overcomes. 
FIG. 4 illustrates the second step in the folding sequence as it is applied 
to the container blank of the present invention. Panels 112, 113 and 114, 
which together form a gusset, are pinched together, and panels 132, 133 
and 134, which together also form a gusset, are pinched together, to form 
a pair of projecting wings which extend outwardly beyond the perimeter of 
the container, while roof panels 132 and 142 are folded along line 205 to 
form a roof. The rib panels are then brought into juxtaposed paired 
alignment for sealing. Second rib panel 116 is sealed to seventh rib panel 
155, third rib panel 123 is sealed to sixth rib panel 143, and fourth rib 
panel 135 is sealed to fifth rib panel 136, thus forming a continuous and 
uninterrupted upstanding multi-ply rib which provides a hermetic closure 
extending the width of the container. In the present invention, however, 
as is shown most clearly in FIG. 3, in contrast to the prior art, the 
seventh rib panel 155 lies between panels 115 and 116 with its free edge 
in score line 210 at the extreme end of the rib. The raw edge of rib panel 
115, as can be seen in FIG. 5, is on the outside of the container. 
As FIG. 6 clearly indicates, the rib panels are positioned in such a manner 
that no disruptive forces are acting upon the seal. Consequently, a 
complete and long-lasting hermetic closure is easily and readily formed 
and maintained. 
In the preferred embodiment, a flat roof with a central upstanding rib is 
obtained by making the height of roof panels 122 and 142 one-half the 
width of the gussetted body panels 111 and 131. For certain purposes, 
e.g., to conserve materials in a substantially cubical container or to 
form a peaked roof, it may be desirable to vary the heights of panels 122 
and 142. Such variations do not impair the effectiveness of the seal and 
are included within the scope of the invention. 
FIG. 7 illustrates the third step in the folding sequence of the present 
invention. Either the third rib panel 123 or the sixth rib panel 143, 
which are sealed together to form the central portion of the upstanding 
multi-ply rib, is then selected and folded at right angles about score 
line 206 to overlie in a substantially flat relationship, either roof 
panel 122 or roof panel 142, depending upon whether the third or sixth rib 
panel is selected. As depicted in FIG. 7, rib panel 123 is folded 
substantially normal to its prior upstanding position to overlie in 
substantially flattened relationship roof panel 122 to which it is then 
sealed. The projecting wings are then folded upwardly and cover panel 124 
is also folded upwardly. 
The seven rib panels, as pictured, are all the same height. This feature, 
while desirable, is not necessary to the invention. It is necessary, 
though, that the selected rib panel, either 123 or 143, be the same height 
as roof panel 122 or 142, so that, at the completion of the third step in 
the folding sequence, score line 207 lies along an outside edge of the 
box. FIGS. 8 and 9 are cutaway views showing more clearly the disposition 
of the various panels at this stage. 
FIG. 10 shows the fourth step in the folding sequence. The projecting 
wings, shown as upstanding in FIG. 7, are now folded inwardly and 
downwardly at right angles resulting in rib panel 115 of one wing and 136 
of the other wing being sealed to and overlying flattened rib panel 143, 
whereby a substantially flat closure is formed. Panels 142 and 143 will 
buckle inwardly slightly to accommodate the wings. 
FIG. 11 shows the fifth and final step in the novel folding sequence of the 
subject invention. Cover panel 124 is folded down along score line 207 and 
over said flattened rib panels and sealed to roof panel 142 to cover the 
entire top of the container. Thus, a flat and seamless covering is 
provided for the closure. The coverting panel also protects the hermetic 
seal underneath from pilferage and breakage during handling. 
Cross-sectional views 12 and 13 show the disposition of the various panels 
beneath the cover in the finished container. As they indicate, the novel 
closure herein presented leaves no raw edges on the inside of the 
container. Furthermore, the triangular wings reinforce the corners of the 
box, making them virtually uncrushable, and giving the container, as a 
whole, exceptional stacking strength. 
The subject container can be made of paperboard coated on one or both sides 
with a thermoplastic substance, such as polyethylene. Alternatively, the 
container can be made of uncoated paperboard having applied thereto a 
heat-sealable material arranged in a particularized pattern to conform 
with the folding sequence described herein, in order to effect a hermetic 
seal. 
Although no opening feature is shown, any opening suitable for a hermetic 
package, such as a tear strip or a single-severable score line, could be 
employed. The dimensions of the container may be varied to suit the 
product, and the shape of the manufacturers flap (excluding its rib 
portion) adapted accordingly. Other modifications will occur to those 
skilled in the art, and while one embodiment has been discussed in detail, 
it is not intended that the invention be limited to that embodiment. 
The terms and expressions that have been employed herein are used as terms 
of description and not of limitation, and there is no intention in the use 
of such terms and expressions to exclude any equivalents of the features 
shown and described or portions thereof, but it is recognized that various 
adaptations are possible within the scope of the invention as claimed.