Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
F-6047 1 -
EXPANSIBLE GROCERY SACK
The present invention relates to a thermoplastic
film grocery sack having handles which are integral
extensions of the walls thereof.
A more or less standard size grocery sack having
its origins in the once-familiar kraft paper gro~ery
sack is the 1/6 barrel size bag. Originally, the cubic
capacity of this bag was approximately 1440 cubic
inches. In present day thermoplastic film grocery
sacks, this volume is somçwhat less. It has been one
of the objects over the years to realize the most bag
volume employing the least amount of bag film for
obvious economic considerations. In U.S. Patent No~
4,554,192, this object was achieved by eliminating the
so-called "trapped gusset" in the bottom of the bag.
By employing diagonal seals in the bottom of the bag,
maximum usable volumetric efficiency could be achieved.
As resin quality has improved and film gauge has
decreased, increased volumetric capacity can be
achieved by economically employing more square inches
of thermoplastic film.
It is an object of the present invention to
present a thermoplastic film grocery sack which is
capable of increasing in girth during use and,
therefore, provide more capacity.
It is another object of the present invention to
provide such a bag which, in addition to increased
volumetric capacity, has the ability to carry more
weight.
The present invention is concerned with a
thermoplastic film bag comprising bottom, front, rear
and gusseted side walls, an open mouth top portion,
said mouth portion having loop handles as integral
extensions of said walls at opposite ends thereof, and
having the improvement comprising including at least
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one pleat extending from the sack bottom to the
uppermost region of the bag.
Fig. l is a front elevation view of the
thermoplastic sack of the present invention;
Fig. 2 is an end view taken along the lines 2-2 of
Fig. l partly expanded;
Fig. 3 is a front elevation view of a fragment of
an alternative version of the bag structure of the
present invention;
Fig. 4 is an end view taken along the lines 4-4 of
Fig. 3 partly expanded;
Fig. 5 is a front elevation view of another form
of the bag structure of the present invention; and
Fig. 6 is an end view taken along the lines 6-6 of
Fig. 5 in partly expanded form.
During the manufacture of the grocery sacks of the
present invention, by placing pleats in the bag
structure, it can be appreciated that a bag of a given
lay-flat dimension can be obtained which, during use,
can expand in girth to yield a greater volume than
would otherwise be obtainable. As employed herein, the
term "pleat" is intended to include all forms of known
pleats. In general, a pleat is a fold made by doubling
material over on itself. In cross-section, pleats can
somewhat res@mble a Z-fold, a W-fold, a V-fold, etc.
The invention contemplates employing at least one pleat
somewhere along a longitudinal top-to-bottom line of a
bag or a plurality of pleats longitudinally located
about the girth of the bag.
Figs. 1 and 2, for example, show a thermoplastic
grocery bag lO having loop handles 12 as integral
extensions of rear walls ll, front walls 13 and side
walls 21. The handles are sealed at the top along line
18 and the bag bottom is sealed along line 20. A
cutout in the bag structure along lines 15 defines the
handle shape in the open-mouth portion. The side walls
21 are inwardly extended to form a gusset along line
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22. The handles are shown including a suspension
orifice 14 illustrated as beiny a straight cut
extending through all 4 or more film layers of the
handle. It is t~ be understood that this orifice can
have any shape which does not material weaken the
strength of the handles. Each of the 4 gusset folds on
opposite sides of the bag are shown to have included
therein pleats 16 which extend from the bottom seal 21
to the handle seal 18. As shown, the pleats are
approximately one-half the width of the gusset fold on
each side of the bag. Thus, in a bag having 3-inch
gussets on each side, the pleats contribute an
additional one and a half inches of film width. During
the loading of such a bag, while opposite ends o~ the
pleats are confined, the central region of the bag in
the handle areas can expand in girth to accommodate an
increased volumetric load. The bag of Fig. 1 can
include an optional tab member at the center of the bag
mouth in order to accommodate the suspension of bag
packs and the dispensing of individual ba~s therefrom.
Bags of the type shown in Fig. 1, collected into a bag
pack arrangement, can be conveniently suspended from 2
elongated parallel rods by threading the pack through
orifices 14. Other conventional means of suspending
and dispensing the bag packs are also contemplat~d,
such as those described in U.S. Patent No~ 4,165,832.
Figs. 3 and 4 show, in fragmented form, a bag
which is, in all essential respects, the same as that
shown in Fig. 1 except that a variation in the use of
pleats is shown. The bag 20 of Figs. 3 and 4 show the
use of a plurality of external pleats 26 extending from
top seal 18 to bottom seal 20. These pleats are
somewhat in the nature of "accordion" pleats which can
permit girth expansion to the cumulative width of the
individual pleat dimensions. In addition, it will be
appreciated that the plurality of pleat folds will add
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F-6047 - 4 -
substantially to the strength of the bag in the region
of the handles.
Figs. 5 and 6 illustrate a bag 30 which, in all
essential respects, is the same as those illustrated in
Figs. 1-4 except that a plurality of pleats 36 are
shown extending longitudinally in the front and rear
walls of the bag Prom the bottom seal 20 to bag mouth
15. These pleats will permit girth expansion of the
bag during filling. Considerable tear resistance in
the bag mouth region can be obtained by impressing a
horizontal seal 38 near the bag mouth in the front and
rear walls of the bag.
As indicated above, the number of pleats in the
bags of the present invention can range from 1 to a
plurality of specifically located pleats. The pleats
can be located in the gusseted side walls, in line with
the handles in the front and rear faces of the bag, in
the front and rear faces of the bag extending from the
bottom to the open mouth top portion, or the pleats may
be located around the entire girth of the bags. The
dimensions of the fold will be dictated by
considerations of numbers of square inches of
thermoplastic film employed in each bag versus the gain
in strength and desired girth expansibility. A
preferred use includes one or two pleats in each gusset
fold.
Bags of the structures described can be formed by
employing any suitable thermoplastic material, ~uch as
a polyolefin, and more particularly~ polyethylene of
any gauge. Gauges ranginy from about 0.25 to about 5
mils are contemplated. In employing the term
"polyethylene" it is employed generically to include
all forms of polyethylene, including low density
polyethylene, linear low density copolymers of ethylene
and another alpha-olefin, high density polyethylene,
mixtures and blends of the same. The contemplated bags
of the present invention can be formed by utilizing
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conventional bag making technology modified by the
inclusion of folding means to include pleats where
desired in the bag structure.
The method of preparing the subject bags can
comprise:
(a) forming a tube of a thermoplastic film;
~b) collapsing said tube while simultaneously
forming therein 2 oppositely disposed, parallel gus~ets
and employing pleat forming means to form pleats in the
collapsed tube;
(c) forming transverse sealing and severing seams
at bag length distances apart across and through said
collapsed tube;
(d) collecting the resulting structures in a
stack; and
(e) forming a handle and bag mouth opening at one
end of the stack. During this latter operation,
appropriate suspension orifices can be formed in the
handles of the bag pack.
Although the present invention has been described
with preferred embodiments, it is to be understood that
modifications and variations may be resorted, without
departing from the spirit and scope of this invention,
as those skilled in the art can readily understand.
Such modifications and variations are considered to be
within the purview and scope of the appended claims.
