Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
I
; PAPERBOARD CONTAINE~ WITH
~` M _LDED BOTTOM CLOSURE
Technical Field
05
This invention relates generally to thermoplastic
coated, liquid carrying paperboard containers and, more
particularly, to an improved thermoplastic coated paperboard
container bottom closure for eliminating edge wicking
throuqh the panel edges Gf the interior container.
Background Art
Coated paperboard containers have been widely used for
packaging milk and other liquid products which do not
require a long shelf life~ These containers have raw edges
because the blanks therefor are cut from large sheets or
rolls. These raw edges are subject to wicking or pene-
tration of the wall panels by the product in a container.
This wicking action eventually weakens the container and
does not permit the container to be used for packaging
liquids which may be stored for long periods of time as, for
example, juices, syrups and the like.
One satisfactory arrangement for eliminating such
internal bottom raw edges is that shown and described in
Miller et al U.S. patent no. 3,412,922. However, on
particular models of forming, filling and sealing machines,
it is desirable to not have to first break along a score
line and then fold back a tab portion of an underlying
bottom panel as a separate operation prior to the folding of
the two outer bottom panels, as is the case in the Miller e~
al arrangement. Another known arrangement is shown and
described in Miller et al U.S. patent no. 3,294,310, wherein
distal half of the "tuck-in" edge portion of the underlying
bottom panel is folded around a score line across the entire
width thereof, prior to completing the folding, tucking and
sealing thereof.
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Di~clo3ure o~ the Inven~lon-
Accordingly, a general object of the invention is to
provide an improved coated paperboard container in which the
raw edges inside of the container have been eliminated so as
to provide a container having a long shelf life.
Another object of the invention is to provide a coated
paperboard container in which a central tab has been formed on
an otherwise non-tuck type underlying bottom panel, and which
is automatically folded under in the forming process to form
a sealed edge in the center of the bottom closure which is
impervious to moisture, and wherein edge wicking action is
eliminated.
Still another object of the invention is to provide a
means for eliminating edge wicking in a coated paperboard
container by folding under a central tab portion formed on a
closure panel without any adjacent free cut edges which would
present a jamming problem on carton forming machines.
The present invention meets the above~defined objects
by providing a method of forming a liquid-carrying container
from a one-piece, flat, thermoplastic coated, paperboard blank
including four body panels and a side seam flap, and four
bottom closure panels, wherein two alternate bottom panels are
triangular gusset panels, and the remaining panels are
rectangular in shape, with one of khe rectangular panels having
a centrally located fold-back tab formed on the edge thcreof,
and the other rectangular panel including an edge extension for
overlapping the other rectangular panel on the outside thereof,
the method comprising the following steps: providing the fold-
back tab with a score line aligned with the edge of the one
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rectangular panel; folcling -the blank in ha].f and securing the
side seam flap to the adjacent body panel edye portion; forminy
the folded blank into a four-sided tubular blank such that the
respective triangular and rectangular panels are oppositely
disposed; placing the tubular blank on a rotatable mandrel;
breaking the two oppositely disposed triangular panels
inwardly; folding the two oppositely disposed rectangu]ar
panels toward each other over the triangular panels; bending
the fold-back tab backwardly along the score line toward and
into contact with its interconnected rectangular panel as the
fold-back tab abuts against the free edge of the extension of
the other rectangular panel as the latter extension
progressively overlaps the one rectangular panel and fold-back
tab; and sealing the bottom closure substantially across the
total length of the overlapped portions of the rectangular
panels.
These and other objects and advantages of the invention
will be apparent when reference is made to the following
description and accompanying drawings.
2U Brief De~cription of the Drawin~s
Figure 1 is a lay-out plan view of the inside surface
of a thermoplastic coated paperboard blank from which a
container bottom closure of the present invention is formed;
Figure 2 is a plan view o~ a side seamed blank made from
the blank shown in Figure l;
Figures 3, 4 and ~ are fragmentary perspective views
illustrating sequentially three of the steps involved in
forming the bottom closure of the present invention;
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Figure 6 is a view of the inside face of the completed
bottom closure; and
Figure 7 is an enlarged sectional view taker. along the
05 plane of the line 7-7 of Figure 6, and looking in the
direction of the arrows.
Best Mode of Carrying Out the Invention
Referring now to the drawings in greater detail,
Figure 1 illustrates the inside surface of a container blank
10. The container blank 10 is separated into three general
groups by staggered score lines 12 and 14. The group above
staggered score line 12 is referred to as top closure group
16. The group between staggered score lines 12 and 14 are
referred to as body group 18. The group below staggered
score line 14 is referred to as bottom closure group 20.
The container blank 10 is defined on its sides by side edges
22 and 24 and is separated vertically by a series of score
lines 26, 28, 30 and 32. The score lines 26, 28, 30 and 32
divide the group body 18 into side wall panels 34, 36, 38
and 40 and side seam flap 42.
Triangular end panels 44 and 46 are connected at the
score line 12 to the upper ends of the side wall panels 34
and 38, respectively. A first pair of fold-back panels 48
and 50 are connected to diagonal score lines 49 and 51 which
define the triangular end panel 44, and a second pair of
fold-back panels 52 and 54 are connected to diagonal score
lines 53 and 55 which define the triangular end panel 46. A
pair of inner rib panels 56 and 58 are connected to the
outer edges of the fold-back panels 48 and 50, respectively,
by score lines 57 and 59. A pair of inner rib panels 60 and
62 are likewise connected to the outer edges of the
fold-back panels 52 and 54, respectively, by score lines 61
and 63.
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A pair of outer roof panels 64 and 66 are connected at
the score line 12 to the upper ends of the wall panels 36
and 40, respectively. A pair of outer sealing rlb panels 68
and 70 are connected at score lines 69 and 71 to the upper
05 ends of the roof panels 64 and 66, respectively. A complete
description of the top closure group 16 is not necessary in
order to understand the principles of the present invention.
However, reference is made to U.S. Patent 3,270,940 which
issued September 6, 1966 for a complete description of a top
closure group similar to top closure group 16.
Insofar as the bottom closure group 20 is concerned, a
pair of outer panels 74 and 76 are connected by the score
line 14 to the lower ends of the side wall panels 34 and 38,
respectively. A pair of triangular in-fold panels 78 and 80
are likewise connected by the score line 14 to the lower
ends of the side wall panels 36 and 40, respectively. A
pair of fold-back panels 82 and 84 are connected by diagonal
score lines 83 and 85, respectively to the panel 7~, and a
pair of fold-back panels 86 and 88 are connected by diagonal
score lines 87 and 89, respectively, to the panel ao. A
rectangular fold-back tab 90 is connected by a horizontal
score line 92 to the panel 74.
An extension 94 is formed on the panel 76 for over-
lapping a portion of the panel 74 as will be explained. A
chamfered edge 96 is formed on the extension 94 to coincide
with a chamfered edge 98 formed on the end of the side seam
flap 42. Except for the fold-back tab 90, the extension 94,
and the chamfer 98, the free edge of the bottom closure
group 20 is a straight line 99.
When the container blank 10 is being prepared for
assembly as a container it will be side seamed by having the
roof panel 66, the side wall panel 40 ad the infold panel 80
and its associated fold-back panels 86 and 88, along with
the side seam flap 42, folded about the score line 30,
moving their inside surfaces into contact with the inside
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surfaces of the triangular end panel 46, the side wall panel
38 and the outer panel 76, with the side seam flap 42
extending past the score line 28.
05 The triangular end panel 44, the side wall panel 34 and
the bottom panel 74 will be rotated about the score line 26
so their inside surfaces will move toward the inside surface
of the roof panel 64, the side wall panel 36 and the infold
panel 78 and the associated fold-back panels 82 and 84. The
side edge 22 will then be substantially aligned with the
score line 32, and its associated edge portion will be
aligned with and in contact with the outside surface of the
side seam flap 42. The outside surface of side seam flap 42
is secured to the inside surface of the various panel
members positioned along the side edge 22. This can be
accomplished in many ways. One of the preferred methods is
heat sealing which will establish a surface bond between the
adjacent members. The container blank 10 can then be opened
into tubular form as illustrated in Figure 3.
In normal production operations the bottom closure
group 20 will be closed and sealed, the contents will be
passed into the ~ubular container member and then the top
closure group 16 will be closed. The forming of the side
seam blank and the closing of the top closure group is
covered in detail in the above mentioned U.S. Patent
3,270,940.
The diagonal edges 96 and 98 of the bottom panel 76 and
the side seam flap 42 are provided so that when the bottom
closure is construc~ed there will not be an extra layer of
paper since the panel 76 will not e~tend over the side seam
flap 42, but, rather, will enter into positlve vertical
alignment with the panel 7~ sealed in between, as may be
noted in Figure 6.
More specifically, completion of the formation of the
bottom closure 20 is illustrated sequentially in Figures
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3-6. Starting with the blank in the open-ended tubular form
illustrated in Figure 3, khe triangular in-fold panels 78
and 80, and their associated fold-back panels 82, 84, 86 and
88, as well as the outer panels 74 and 76 are first broken
05 inwardly, as shown in Figure 4. They are then subjected to
fairly inkense heat, rendering the outer and inner layers of
plastic material, such as polyethylene, adhesively active.
By referring to Figure 5, it may be noted that
prebreaking of the tab 90 along the score line 92 is not
re.quired in the typical forming operation on a forming,
filling and sealing machine, inasmuch as the tubular blank
(Figure 3) is mounted on a mandrel 100 which is shown in
Figure 5 rotating in a counterclockwise rotation. This
causes the outer panel 76 to be bent further downwardly
about the score line 14 upon contacting a fixed forming shoe
102. A tucking finger 104 is thereupon pivoted about a
pivot pin 106 in a clockwise direction, causing the outer
panel 74 to bend downwardly about the score line 14, bringing
the tab 90, but not the panel 74, into contact with the free
edge 108 of the extension 94 of the outer panel 76. Thus,
no jam-up between the panels 74 and 76 are possible, and the
tab 90 is efficiently bent backwardly about the score line
92 to become flattened against the panel 74 beneath the
extension 94 where it becomes sealed. With the tab 90
confined between the underlying integral outer panel 74 and
the overlying outer panel 76, there are no raw edges within
the bottom closure 20, but rather a sealed edge 92, as seen
from inside the container (Figure 6). On the outside of the
container ~Figure 7), a continuous seal is now formed
between the extension 94 and the panel 74 adjacent the tab
90, running the full width of the extension 94. This,
therefor, eliminates any chance for channel leaks to occur
along the edges of the covered tab 90.
The raw edge 24 along the length of the side seam flap
42 may also be eliminated by using the folded-over edge
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arrangement shown and descrlbed in Miller et al Patent
No. 3,412,922, and forming no part of the present invention.
Industrla ~ plicability
05
It should be apparent that the invention provides a
simplified, efficient means for eliminating raw panel edges
on the inside surfaces of the bottom closure.
While but one embodiment of the invention ha.s been
shown and described, other modifications thereof are
possible.
