Note: Descriptions are shown in the official language in which they were submitted.
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RECLOSABLE CONTAINER ~ITH GRIP STRIP
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In reclosable plastic bags or other con-
tainers, particularly those containing a zipper type
l~ reclosable closure such as taught in Patent 4,263,079,
,, the container usually carries lips located above the
reclosable closure feature, which lips are required to
~ be grasped between the thumb and a finger, for example,
'~ and pulled to open the closure. Some degree of force
is necessary to open the closure, which is relatively
secure to avoid accidental opening. Since such bags
are often found in the kitchen, it is not uncommon for
one's fingers to be greasy. Since lips of such bags
ar~ commonly formed from smooth films such as those
formed of polyolefin resin, the ease with which the
lips of the bag can be grasped and kept hold of while
pulling during opening can be easily negated when the
fingers are greasy. Attempts to solve the lip grasping
problem have generally included one, two or three large
ribs, which are close to the same size as the closure
` elements themselves, such as illustrated in U.S. Patent
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4,363,345, for ~xample. Such large ribs are purported
; to improve gripping o~ t~e container lips by the user
during the opening and loading of the container.
However, use of large ribs has been found to cause some
forming complications because of their size, in that
undulations can occur during extrusion. Such large
ribs have also been found in many instances not to be
as comfortable to the user as they might be, some
effort is required on the part of the user to locate
the large ribs and such large ribs require considerable
amount of resin material to form especially if more
than one or two of them are employed.
Applicants have found that a far more desir-
able, improved arrangement îs where the size and the
number of protuberances are in between those that are
merely employed for roughening a surface as a spacing
means for nonblocking and those ribs which are large
and small in number, such as previously designed to aid
in gripping of lips of reclosable plastic bags.
The present invention is an improvement to
reclosable plastic containers, such as bags, ensuring
ease of grasping of the lips of bags both from a loca-
tion and securing standpoint, the improvement simul-
taneously leading to ease of manufacture of such con-
tainers containing such improved grasping feature,
hereinafter called grip strips. This improvement is
accomplished by modifying -the lip of a reclosable bag
by including on opposed surfaces thereof a plurality of
generally parallel small ridges in order to provide a
large area of ridged surface to grip the top or lip of
th~ bag when opening or filling the bag. It has also
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been found that when a larger number of ridges are
used, the ridges can be considerably smaller than when
a single rib is employed and still produce an improved
gripping surface. It has further been found that a
plurality of small ridges are easier to produce than
fewer large ribs. Small ridges require less
modification to the die when added to the film by
extrusion. In addition, small ridges can be produced
by other techniques than extrusion such as by
0 embossing, and a plurality of such small ridges can
also provide reinforcement for the lip of the bag. It
has been discovered that a series of generally parallel
ridges presenting a gripping edge or edges and being
about 0.002 to 0.009 (preferably 0.003 to 0.005) inches
(.05 to .23, preferably .08 to .13 mm) in height and
spaced at a density of about 7 to 24 (preferably 12 to
16) ridges per lineal inch (2.54 cm) of film in the
region above the reclosable feature would provide the
20 advantages of this invention.
In particular, the present invention resides in
a reclosable container having clo~ure elements provided
in an upper lip portion of opposing side walls of the
25 container, sections of the lip portion above the
closure elements each containing a grip strip, said
grip strip comprising three or more ridges extending
substantially along the length thereof, each of the
ridges being generally parallel to one another and
3 having a height of no greater than 0.009 inches (0.23
mm) and no less than 0. 002 inches (0. 05 mm).
The invention also resides in a reclosable,
flexible container made from thermoplastic film or
35 sheet stock, comprising a container body having a pair
of opposing side walls which are sealed at one end and
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which provide an opening at the opposite end, a closure
. device adjacent the open end of said container, said
closure device comprising releasably interlocking male
and female profiles integral with the walls and
positioned on the inner surfaces of the side walls in a
facing relationship, said male and female profiles
being separable from each other by drawing the profiles
apart and being interlockable by pressing the profiles
together, and opposed flange portions on the upper
~ exposed edges of the side walls above the profiles
which may be gripped and drawn apart to separate the
interlocked profiles from each other to open the
container, wherein at least one of said opposed flange
portionY is provided with a plurality of parallel
gripping ridges, said ridges having a height of from
0.05 mm to 0.23 mm and being spaced from each other at
a density of from 7 to 24 ridges per lineal inch (2.75
to 9.5 ridges per cm) of film above the closure device.
The invention further resides in a method of
forming a reclosable container made from a
thermoplastic film on sheet stock, said container
comprising a container body having a pair of opposing
side walls which are sealed at one end and which
provide an opening at the opposite end, opposed flange
portions on upper exposed edges of the side walls, and
a plurality of gripping ridges formed in a grip strip
on at least one of the upper exposed edges of the side
3 walls, comprising the steps of forming three or more
cut-away sections on an extrusion die adapted to form
said ridges on the film coextruded adjacent said
; ridges, spacing the cutouts a distance so that the
ridges are spaced so as to have at least seven ridges
per lineal inch (2.54 cm) in the width of the grip
33,754-F -3a-
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strip, shaping the cut-aways so as to present a
gripping edge on the ridges, and drawing down the grip
strip so as to maintain generally the gripping edge,
and maintaining at least seven ridges per lineal inch
(2.54 cm) of grip strip.
. The invention is further illustrated by the
following drawings wherein:
~$ ~o Figure 1 is a perspective view of a reclosable
Z bag with improved grip trips of this invention;
' Figure 2 is a side elevational view of the bag
~ of Figure 1 partially broken away to show a grip strip
3 15 on the inside of one lip;
Figure 3 is a partial plan view of an extrusion
die employed for extruding the ridges forming the grip
strip on a lip of the bag shown in Figure 1;
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Figure 4 is an enlarged fragmentary plan view
of the low~r edge of the die plate shown in Figure 3;
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Figure 5 is an enlarged cross-sectional view
of a grip lip having a single ridge as typically
employed in the prior art;
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. Figure 6 is a view like Figure 5 only showing
a grip strip with a plurality of ridges formed in
accordance ~ith the principles of the present invention
and manufactured using the die plate of Figure 3;
Figure 7A - 7E is a cross-sectional view of
various embodiments of grip strips of the present
invention showing some variation in .ridge spacing,
shape and size; and
, Figure 8D shows an enlarged cross-section of
,~ 15 the ridge o 7D, and Figur~ 8E being an enlarged cross-
,; section of the ridge of Figure 7E.
Referring more particularly to Figure 1,
there is shown a container or bag 10 having opposed
side walls 12 and 13, reclosable fastener elements 14,
opposed lips 16 and 18, each opposed lip containing
grip strips 20 and 21 respectively, which grip strips
provide for improved ease of opening and holding the
bag for filling. Figure 2 is a view like Figure 1
showing through a broken away section the inside of
side 13 of the bag 10 with its lip 16 and grip strip
20, the latter comprising a plurality of elongated
generally parallel ridges 22 extending from substan-
tially one edge 15 of the bag to the other edge 17 as a
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strip or band across lip 16 above reclosable fastener
18. Ridges 24 are preferably substan~ially continuous
along their length.
Bag lO can be formed in a process such as
shown and described in U.S. Patent 4,515,647, with the
,, cut-away 30 of a die 29 for grip strip ridges 22 being
located to the outside of the extrusion openings 31 of
each profile extrusion such as shown in fragmentary
Figure 3. Cut-away 30 in the front or lower edge of
the die 29 form teeth-like die projections 32 being
shown in somewhat exaggerated detail for clarity. The
cut-aways 30 which form the ridges 22 of grip strip 20
for example, are shown to be of a triangular configur-
ation so as to provide ridges 22 with a generally tri-
angular configuration, as shown in Figure 6, forexample and described in more detail later.
In greatly enlarged Figure 4 a land 34 between
cut-aways 30 is purposely not as great as the spacing
"x" between the peaks 25 of adjacent ridges 22. Again,
as seen in the grip strip 20 in Figure 6, as compared
to the cut-aways 30 in die 29, because of the draw down
occurring in the extrusion process, the land area 34
~Figure 4) between cut-aways 30, which form ridges 22,
is greatly extended to the distance roughly shown as
about "x" minus the width "w" of one ridge 22 (Figure
6). Not only is the spacing between the ridges 22
effected by the draw-down in the extrusion process, but
also the particular shape of each of the ridges 22 as
disclosed hereinafter. The cut-away openings 30 can
take various configurations approaching a rectangle,
¦ all the way to a saw tooth type opening, such as a
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right triangular configuration or take the shape of aequilateral triangle. Prefera~ly a shape is desired
which can present at least an edge to be engaged by a
finger or a thumb when gripping the lip to open the bag
containing a grip strip 20, such as shown in gripping
edge 41 of ridge 22 in Figure 8D or gripping edges 42
; of ridge 43 in Figure 8E, which edges are shown slightly
rounded because some rounding occurs in draw-down
during the extrusion process.
Figure 5 illustrates a grip lip 36 of the
prior art which has a film thickness "t" of about two
to three thousandths of an inch (O.05 to 0.08 m~l), and
a grip lip height llhll of from two to five hundredths of
an inch (0.5 -to 1.3 mm). There generally are only one
; 15 or two such ribs 36 on a grip lip.
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In the grip strip cross-section shown in
, Figure 6, the film thickness "t" can be about the same
as that in Figure 5, that is about two to three thou-
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. sandths of an inch thick (0.05 to 0.08 mm), but the
ridges are only about two to nine thousandths of an inch
~ (0.05 to 0.23 mm) tall and they are spaced at a density
: of about 12 to 16 ridges per lineal inch (2.54 cm) of
film across the grip strips width w, which in the
illustration shown in Figure 6 gives a spacing x of
about 0.06 to 0.08 inches (1.5 to 2.0 mm) from tip 23
to tip 23 of adjacent ridges 22.
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Various modifications of this invention are
: shown in Figure 7A - 7E, for example, all on about the
. same scale (50 times actual size) as that used for
Figures 5 and 6, the various ridge heights and ridge
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spacing. While all of these embodiments are operable
(the embodiments of Figules 7B through 7E were actually
made), if there was a preference it would be for the
embodiment of Figure 7D. The number (7) for Figure 7A,
' 5 (12) for Figure 7B, (24) for Figure 7C, (16) for 7D,
and (20) for 7E gives the number of ridges 22 or ridges
43 per inch (2.54 cm) of film being about 7 to 24
' (preferably 12 to 16), 16 ribs per inch (2.54 cm) of
film and with ridges from 0.002 to 0.009 inches (0.05
to 0.23 mm) tall preferably .003 to .005 inches (0.08
to 0.13 mm) tall. If one goes much below 0.002 inches
(0.05 mm) in height ridges became difficult to feel.
While a higher ridge may be easier to feel, it requires
more material to form and is more difficult to form, as
explained earlier.
It has been found that using a plurality of
much smaller ridges 22 as shown in grip strip 2~ o
, Figure 6, that no more material need be used than used
i with a single grip strip on a bag lip such as shown in
Figure 5, and yet several advantages are obtained over
such a configuration. For one it was found that it was
, easier to match the flow velocity of the grip strip
', area with that of the film during extrusion when a
series of small ridges are used and that this essenti-
ally eliminated undulation extrusion problems of the
kind that are experienced when trying to match the
velocity of a single relatively large grip lip rib,
such as rib 36, to that of the flat film being
coextruded therewith. Another advantage of using a
plurality of small ridges is that there was provided
uniform gripping essentially over the entire lip. Not
only does a grip strip according to this invention
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- provide a better feel, but it is more foolproof because
one can grip the lip anywhere and find more than one
ridge upon which t.o engage fingers for pulling zippers
or other reclosable elements apart or holding the bag
even with greasy fingers. In one survey taken, for
example when comparing the grip strip of the present
invention, with the prior art with a single large rib
on each bag lip of those surveyed with dry hands only
'! 29 percent preferred the-prior art grip lip as against
63 percent for the grip strip of this invention, while
8 percent thought that they were about e~ually effective.
With greasy hands, the numbers were 25 percent, 72 per-
cent and 3 percent, respectively showing an overwhelming
preference for the grip strip of this invention~ espe-
cially with greasy hands where the test is the mostsevere.
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