Easy-open bag pack, method of forming and system

A system for suspending a pack of thermoplastic bags, loading bags, removing loaded bags and for automatically opening the next bag preparatory to loading it by having a pack of handled bags suspended from laterally spaced elongated rods of a rack. A novel gradually releasably adherent bond is created between the rear wall of a leading bag and the front wall of a following bag in the bag pack. As the leading bag is removed from a bag rack, the bond will gradually and fully open the mouth and body of the following bag for loading.

FIELD OF THE INVENTION 
The present invention is concerned with a pack of bags of the thermoplastic 
film type wherein each bag is in the layflat condition. It is also 
concerned with a method of forming bags and bag packs and a system 
utilizing the bag packs. More particularly, the present invention relates 
to a pack of bags wherein each bag is treated, structured and used so that 
the foremost bag is always in an opened or partially opened condition and, 
therefore, ready for filing without substantial time lost accessing the 
bag mouth of each bag. 
BACKGROUND OF THE INVENTION 
Since the commercial introduction of the plastic film grocery bag in this 
country, its acceptance has steadily grown because of its many advantages 
over kraft paper grocery bags. The many advantages connected with 
present-day plastic grocery bags include their ability to be unaffected by 
water, the fact that they are not as bulky as paper grocery bags, are less 
expensive and stronger than paper bags, as well as the fact that most have 
carrying handles, making them easier to use. 
However, because of the inherent lack of rigidity of the plastic film 
employed in the manufacturing of these bags, special means are required 
for suspending packs of plastic bags and for holding the foremost bag in a 
pack in a position conducive to filling the bag. As may be readily 
appreciated, long lines at the checkout counter of a supermarket are 
annoying to the customers and baggers. If a bagger utilizing plastic bags 
has to fumble to open each bag, productivity suffers. 
In certain bag dispensing systems wherein the bag pack is used in 
conjunction with a suspension and dispensing means, the use of plastic 
bags will outperform paper grocery bags from an ease-of-handling and time 
standpoint. There is, however, always room for improvement, and any 
innovation which will cut down handling time and/or in any way facilitate 
the use of such bags amounts to a significant advance in the art. 
Disclosures which relate to improvements in plastic grocery bags and 
dispensing systems include U.S. Pat. No. 4,165,832 to Kuklies et al., 
which describes packs of thermoplastic grocery sacks wherein the 
individual bags are designed to be held in registration by being thermally 
welded together at a suspension tab member which extends from the center 
region of the bag mouth. While this type of unitization is effective in 
maintaining the sacks in secure uniform registration at the bag mouth 
region, they do not keep the handles in registration. Such a bag pack is 
structured to be suspended from the center of the pack and it is awkward 
during dispensing and bag filling to deal with the loose unsecured handles 
particularly in bag packs containing over 100 bags in the pack. 
U.S. Pat. No. 4,676,378, issued to Baxley et al., discloses a technique for 
suspending a pack of bags from the handles of the bags in the bag pack. 
The suspension points are located intermediate the top and the bottom of 
the handles. This is accomplished by threading each stack of handles onto 
anchored spaced parallel suspension rods through a suspension orifice in 
each handle. This means or manner of suspension permits individual bags to 
be opened with one swipe of the hand, leaving the bag in its opened 
condition, i.e., front panel separated from the back panel, with the 
handle loops spread open and suspended from the suspension rods. This 
broad means will be the suspension means involved in the instant 
invention. 
The Baxley et al. patent also discloses a technique for automatically 
opening the next bag in a suspended bag pack as a loaded bag is removed 
from the system. This is essentially the same technique as is disclosed in 
U.S. Pat. No. 4,106,734, issued to Walitalo, which teaches suspending 
handle-less bags from suspension rods and utilizing an adhesive area just 
below the bag mouth on the front of each bag in the pack. This arrangement 
causes the next adjacent bag in the pack to be in separable adhesive 
contact with the bag that precedes it. Thus, after a bag is loaded and 
during removal of the loaded bag from the rack, the front panel of the 
following bag will tend to follow along a short distance before release. 
This action causes each following bag to more or less automatically open 
as a filled bag is removed. 
U.S. Pat. No. 4,796,759, issued to Schisler, is directed to a pack of 
thermoplastic film handled grocery sacks. A hole is present in each handle 
so as to receive a rod therethrough designed to support the bag pack by 
the handles. A center support tab extends from the mouth of each bag and 
the tabs are joined together by welding or gluing to secure the bags in a 
pack. A line of perforations separate the support tab from the bag mouth. 
Below the perforation line of each bag is a "glued or welded localized 
zones 9" which ensures connection between the rear wall of one bag and the 
front wall of the next bag and so on through the bag pack. Above this 
point 9, the welded-together support tabs maintain the bags in 
registration and the localized glued or welded zones 9 assists in opening 
the bags during the dispensing and loading of the same. This construction 
also has the disadvantage that no provision is made for maintaining the 
handles in registration. 
While these techniques of enhancing the system of suspending, dispensing 
and filling grocery sacks have merit, those involving adhesives have the 
disadvantage of leaving each bag with a more or less localized tacky 
region on the outside surface of each bag. As may be appreciated, the use 
of adhesives introduce an additional messy step into the manufacturing 
process. 
U.S. Pat. No. 5,335,788 to Beasley discloses self-opening polyethylene film 
bag stacks which do not utilize a separate adhesive layer between bags in 
the stack. At least an upper portion of the outer surface of the front and 
rear walls of each of the bags in the bag stack are corona treated. At 
least one compressed area extends transversely through the bag stack in 
the upper portion of the bags such that the stack has a decreased 
thickness in the localized area and so that adjacent outer wall corona 
treated surfaces defined by the localized compressed area are releasably 
adhered together. 
Other advances include U.S. Pat. No. 4,811,417, issued to Prince et al., 
which shows a bag pack having vertical slit support handles therein, 
wherein the handles are melt-bonded together at the top by means of a 
heated pin device. 
In U.S. Pat. No. 4,989,732, which is incorporated herein by reference in 
its entirety for all that it discloses, there is described a system for 
suspending and dispensing grocery sacks. The bag packs are suspended 
through orifices in the handles by a pair of spaced parallel cantilevered 
rods. Dispensing of the bags in a manner which will cause the next 
following bag to be partially opened upon removal of a lead bag is 
facilitated by the provision of pressure bonded areas in the handles and 
in the region of the bag mouth. As a lead bag is removed the next adjacent 
bag tends to follow along for a short distance during which the front 
panel of the bag separates from its rear panel. When the lead bag finally 
releases from the following bag, the next bag is in a partially opened 
condition so that the supermarket bagger can easily access the interior of 
the bag. 
Application Ser. No. 07/529,806, filed on May 29, 1990, which is a 
continuation-in-part of application Ser. No. 07/495,070, filed on Mar. 19, 
1990, the contents of which are incorporated herein by reference, 
discloses a thermoplastic film bag pack comprising a plurality of the bags 
stacked in at least general registration in a layflat condition, each of 
the bags comprising a bottom, side walls and an open mouth top portion, 
the open mouth portion comprising handles located at opposite end regions 
thereof, at least a portion of the external surface of the film of the 
open mouth and handles region having been subjected to a corona discharge 
treatment to such an extent that the pressure and cutting action forming 
the bag mouth and handles will cause adjacently facing corona discharge 
treated cut-edge regions to releasably adhere together until a moderate 
force separates them. 
Despite these advances in the art, it would be a significant advance if 
further handling time reductions or improvements which, in any way, 
facilitate the use of such bags could be accomplished. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there is provided a thermoplastic 
film bag pack comprising a plurality of bags stacked in at least general 
registration in a layflat condition, each of the bags comprising a bottom 
wall, a front wall, a rear wall, gusseted side walls and an open mouth top 
portion, the mouth portion having double film loop handles at opposite 
ends thereof, the handles being integral extensions of the front, rear and 
side walls, each of the walls having an interior and exterior surface, 
wherein at least a portion of each the external surfaces of the front and 
rear walls are subjected to a corona discharge treatment to an extent 
effective to cause adjacently facing corona discharge treated surface 
portions of adjacent bags within the bag pack to releasably fuse to each 
other upon a localized application of force, the force applied by 
contacting the bag pack with at least a first pair of anvil means, the 
pair of anvil means including a lower anvil means positioned to contact 
the bottom bag of the bag pack within the corona discharge treated surface 
portion of the bottom bag and an upper anvil means substantially aligned 
with the lower anvil means and positioned to contact the top bag of the 
bag pack within the corona discharge treated surface portion of the top 
bag, the pair of anvil means having a force applied thereto effective to 
cooperatively form at least one releasable fused region within the corona 
discharge treated surface portions of each bag of the bag pack. 
The present invention is also concerned with a method of forming a pack of 
gusseted, polyethylene film, integrally-extended handle bags comprising: 
(a) providing a collapsed tube of polyethylene film; (b) corona discharge 
treating at least a portion of the external surfaces of the tube; (c) 
forming side gussets in the tube; (d) transverse-sealing the tube at 
bag-length distances apart to form a series of end-sealed gusseted 
pillowcases; (e) separating and stacking a plurality of the pillowcases in 
at least general registration; and (f) severing all the film layers along 
a line so as to form integrally extended double film loop handles and an 
open mouth region in each bag and simultaneously or sequentially forming 
handle support orifices in each handle; and (g) applying localized 
pressure to at least one end of the stack by contacting the stack with at 
least a first pair of anvil means, the pair of anvil means including a 
lower anvil means positioned to contact the bottom bag of the stack within 
the corona discharge treated surface portion of the bottom bag and an 
upper anvil means substantially aligned with the lower anvil means and 
positioned to contact the top bag of the stack within the corona discharge 
treated surface portion of the top bag, wherein the pressure applied 
thereto is effective to cooperatively form at least one releasable fused 
region within the corona discharge treated surface portions of each bag of 
the stack. 
This invention further concerns a method for forming a gradually releasably 
adherent bond between bags in a bag pack, each bag in the bag pack having 
a mouth and two handles, comprising: a) providing a bag pack comprised of 
individual bags having exterior surfaces, the exterior surfaces having at 
least one corona discharge treated region; b) positioning the bag pack 
between at least a first pair of anvil means, the anvil means comprising 
an upper anvil means and a lower anvil means; wherein the upper anvil 
means comprises a concave-surfaced anvil having a cross section 
substantially encompassing the lower anvil means and the lower anvil means 
comprises at least two tangentially aligned convex-surfaced anvils; c) 
compressing the bag pack between the at least one pair of anvil means in 
the at least one corona discharge treated region to form at least one 
gradually releasable fused region connecting a rear wall of a leading bag 
to the front wall of a following bag in the bag pack; wherein the 
gradually releasable fused region comprises fused zones and a non-fused 
zone; wherein the fused zones have substantially the same strength as a 
non-compressed region of the bag pack. 
It is particularly preferred to create this gradually releasable adherent 
bond between bags using four fused releasable regions arranged in two 
pairs. An upper pair is positioned just below the bag mouth with one fused 
releasable region directly below each bag handle. A second lower pair is 
positioned directly below the first pair at a distance of about 5.08 cm (2 
in). It has been found that this arrangement of four fused releasable 
regions results in the full opening of the entire body of the bag. This 
ability is a significant improvement over the prior art which is effective 
to open only the area near the bag mouth. 
The invention also relates to a system for suspending a pack of bags, for 
loading bags, for removing loaded bags and for automatically opening the 
next bag preparatory to loading comprising; a pack of bags suspended on a 
rack, the rack comprising a pair of laterally-spaced, elongated support 
rods having leading ends; the bag pack comprising a plurality of bags 
stacked in at least general registration in a layflat condition, each of 
the bags comprising a bottom wall, a front wall, a rear wall, gusseted 
side walls and an open mouth top portion, the mouth portion having double 
film loop handles at opposite ends thereof, the handles being integral 
extensions of the front, rear and side walls, each of the walls having an 
interior and exterior surface, wherein at least a portion of each the 
external surfaces of the front and rear walls are subjected to a corona 
discharge treatment to an extent effective to cause adjacently facing 
corona discharge treated surface portions of adjacent bags within the bag 
pack to releasably fuse to each other upon a localized application of 
force, the force applied by contacting the bag pack with at least a first 
pair of anvil means, the pair of anvil means including a lower anvil means 
positioned to contact the bottom bag of the bag pack within the corona 
discharge treated surface portion of the bottom bag and an upper anvil 
means substantially aligned with the lower anvil means and positioned to 
contact the top bag of the bag pack within the corona discharge treated 
surface portion of the top bag, the pair of anvil means having a force 
applied thereto effective to cooperatively form at least one releasable 
fused region within the corona discharge treated surface portions of each 
bag of the bag pack the fused region releasably adhering until a moderate 
force causes separation; aligned mounting orifices in association with the 
handles located between the top and base of the handles; the pack mounted 
on the support rods through the orifices so that during removal of a bag 
from the bag pack at least a portion of the mouth and handle region of the 
front wall of the next bag will follow the bag being removed for a short 
distance before separation thereby opening the next bag rendering it ready 
for loading. 
Therefore, it is an object of the present invention to provide a pack of 
thermoplastic film grocery sacks having integrally extended handles with 
support means in association with the handles. 
It is another object of the present invention to provide a system for 
suspending a pack of bags, for loading bags, for removing loaded bags and 
for automatically opening the next bag preparatory to loading. 
It is a further object of the present invention to provide a method of 
forming a pack of gusseted, polyethylene film, integrally-extended handle 
bags. 
Still another object of the present invention is to provide a bag pack 
having releasable fused zones which are created without substantial 
weakening or deformation of the material making up the walls of the 
individual bags in the bag pack. 
Another object of the present invention is to provide a large, gradually 
releasably adherent connection between a leading bag and a following bag 
in a bag pack. 
Still a further object of the present invention is to provide a plurality 
of gradually releasable adherent connections between bags in a bag pack so 
as to fully open a following bag as a leading bag is removed from the bag 
pack. 
Yet another object of the present invention is to provide a releasable 
fused region between bags in a bag pack wherein the region contains fused 
and non-fused zones. 
Other objects and the several advantages of the present invention will 
become apparent to those skilled in the art upon a reading of the 
specification and the claims appended thereto.

DETAILED DESCRIPTION OF THE INVENTION 
In FIG. 1 there is shown a partial segment of a bag pack 10. The lower part 
of the bag pack is as shown in FIG. 2 and its details are conventional in 
structure and, thus, form no part of the invention disclosed herein. Pack 
10 is shown suspended from rack 12. To accomplish this, the handles 11 are 
threaded onto parallel arms 14 by way of optionally curved orifices 16. 
The individual bags of the bag pack shown have double-film loop handles by 
virtue of the fact that the bags were made from gusseted pillowcases as is 
well known in the art. FIG. 2 shows handles 11 of bag 30 almost fully 
extended on support arms 14. FIG. 1 shows cut line 24, which defines the 
inboard configuration of the handles, the bag mouth region and a center 
tab region used for center support of the bag pack. The center tab region 
includes an orifice 20 utilized for receipt of a suspension member, such 
as a tongue 22. A separate tab is in association with the front and rear 
panels of each bag at the mouth region. The front tab has, near the base 
thereof, a severance line 18 which may be a continuous severance or there 
may be a small tie connection 19 at each end. In either case, the strength 
of the material holding the front portion of the bag to the hanger tab 
area must be small enough to allow the "fusion" of the film layers to 
cause the attached areas to break on the trailing bag. This severance line 
permits a supermarket bagger to gain easy access to the front panel of the 
first bag in a pack preparatory to loading the bag. The rear tab is 
connected by a perforation line to the back panel of each bag. 
The essence of the invention is the provision of a system which permits the 
automatic opening of a following bag during the removal of a loaded bag. 
This is accomplished by causing at least some part of the upper regions of 
the outside surfaces of each bag to lightly adhere to one another in 
chain-like fashion. The aggressiveness of the adhesion should only be 
enough to break any front tab connection to the front wall of the 
following bag and cause the upper portion of the front wall to follow the 
upper portion of the back wall of the bag being removed, for a short 
distance, such as that shown in FIG. 2. 
Referring now to FIG. 3, this phenomenon is accomplished by pretreating the 
external surfaces of the flattened tubular bag stock polyethylene film 
material with corona discharge 36 and coupling this with pressure applied 
by contacting the bag pack 10 with at least a first pair of anvil means 
60, the pair of anvil means including a lower anvil means 64 positioned to 
contact the bottom bag of the bag pack 10 within the corona discharge 
treated surface portion of the bottom bag and an upper anvil means 62 
substantially aligned with lower anvil means 64 and positioned to contact 
the top bag of the bag pack 10 within the corona discharge treated surface 
portion of the top bag. As may be appreciated, the pair of anvil means 60 
are brought together to contact the bag pack 10 and a force is applied 
thereto which is effective to cooperatively form a releasable fused region 
54 (see FIG. 1) within the corona discharge treated surface portions of 
each bag of bag pack 10. When the corona discharge treatment region at 
least involves the upper region of what will become the top front and back 
of the bag, plus the aforementioned application of force, the automatic 
bag opening will result during use of the packs according to the present 
system. 
The strength of the adhesion of the releasably fused regions is 
comparatively small. Yet, small as it is, it is strong enough to break any 
properly designed tab ties 19 located at the ends of severance line 18. 
For example, with about 0.45-0.75 mil films,, tab ties of up to 4.76 mm ( 
3/16 in) are easily broken. Thus, the force necessary to break the adhesion 
is also comparatively small. This force is supplied by the drag caused by 
the full weight of the entire following bag, by the drag of the handle 
film material against the support rod material and/or by the resistance 
caused by the turned-up ends 26 of the support rods 14. As shown in FIG. 
2, bag 28 has separated from bag 30 by reason of one or all of these 
causes and bag 32 remains adhered to bag 30 but is in the early stage of 
opening. 
FIG. 3 illustrates schematically the formation of the treated bag packs. A 
convoluted roll 34 of a flattened tubular film is the precursor for the 
individual bags. This film material can be any thermoplastic material 
which can be treated with corona discharge and be utilizable in the system 
of the present invention. A suitable class of materials are the 
polyethylenes generically, including homopolymer polyethylene of high, 
intermediate or low density, linear low density copolymers of ethylene and 
another C.sub.3 -C.sub.10 alpha-olefin (LLDPE), and any blends of the 
foregoing. The thickness of the film is that normally used for grocery 
bags and may range from about 0.3 to about 1.5 mils greater. A preferred 
thickness is from about 0.45 to about 0.75 mils. Any size bag is 
contemplated but the 1/6 barrel size bag and smaller is preferred. 
The film material is passed in the direction of arrow 52 between two 
oppositely disposed corona discharge treaters 36 positioned so as to treat 
the outside surfaces of the collapsed tube. The treatment can be 
intermittent so as to treat a designated region or regions of the film or 
it may be a continuous treatment affecting all of the outside of the bag 
or that of a narrower stripe restricted to, e.g., the upper-center region 
of the bag. Corona discharge treatment equipment is readily available 
commercially. Appropriate equipment can be obtained from Solo Systems 
Inc., Garland, Tex.; Corotec Corp., Collinsville, Conn.; and others. The 
film should be treated to a surface tension level of at least about 38 
dynes/cm, in accordance with ASTM Standard D2578-84. A range of between 
about 40 to about 50 is preferred. Using Solo Systems equipment, each 
treater can have an air gap of 0.060 inch when treating LLDPE film of 
about 0.65 mils. The treatment area can include a center region of the 
film about 11 inches wide, treated to 40-44 dynes/cm, as is particularly 
preferred. 
After this degree of treatment, the tube is passed through a gusseter 38 
which includes a gusset of from about 3 to about 5 inches into the 
collapsed tube. The tube proceeds to a transverse heat seal means 40 of 
conventional design which imposes heat seals 50 at bag length distances 
apart. Such a heat seal means is usually a resistance strip or bar, 
positioned to put a transverse seal across the gusseted tube at bag length 
distances apart. The sealed tube then proceeds to a combination of 
differential speed rollers which separates the tube into end-sealed 
gusseted pillowcases 44. The pillowcases are then stacked to the 
appropriate number desired, e.g., 50, 75, 100, 125, etc., and, either in 
line or at a remote location, a cutting device 48 applies pressure and 
cuts one end of the stack so as to remove plastic, leaving the shape of 
handles, a bag mouth and center suspension tabs in the bag pack. This 
cutting device 48 may also include means for including a suspension 
orifice in the handles of the bags. The orifice can be of a variety of 
shapes, e.g., a circle, part of a circle with a flap remaining therein, a 
curve of less than one-quarter of a circle, a straight slit, a teardrop 
cutout, a zig-zag orifice, etc. As shown in FIG. 1, handle suspension 
orifice 16 is a curved slit facing inward of the handles so that any 
tendency to tear will propagate toward the inner edge of the handles 
rather than to the center thereof where it would weaken the handles. 
Also, either in line or at a remote location, to releasably fuse the 
treated surfaces of adjacent bags to each other, a localized force is 
applied. As indicated above, the force is applied by contacting bag pack 
10 with at least a first pair of anvil means 60, the pair of anvil means 
60 including a lower pack 10 within the corona discharge treated surface 
portion of the bottom bag and an upper anvil means 62 substantially 
aligned with the lower anvil means 64 and positioned to contact the top 
bag of the bag pack within the corona discharge treated surface portion of 
the top bag. Following bringing the anvil means in close contact with each 
other, the bag pack 10 being in between the upper and lower anvil means 62 
and 64, the pair of anvil means 60 then have a force applied which is 
effective to cooperatively form at least one releasable fused region 54 
within the corona discharge treated surface portions of each bag of the 
bag pack 10. It has been found that for a stack of 100 bags composed of 
low density polyethylene a force of about 9,764-12,205 kg/m.sup.2 
(2000-2500 lb/ft.sup.2) is required to create the releasable fused region. 
This amount of force is much less than that disclosed in the prior art. 
Turning now to FIG. 6, a side view of the novel upper and lower anvil means 
62, 64 is shown just before they contact the bag pack 10. The lower anvil 
means is positioned below the bag pack 10 and comprises a plurality of 
tangentially aligned anvils. As shown and particularly preferred, the 
lower anvil means 64 includes at least three convex-surfaced anvils 
triangularly aligned. The upper anvil means 62 is positioned above the bag 
pack. It includes a concave-surfaced anvil having a cross-sectional 
diameter which substantially encompasses the lower anvil means 64. FIG. 7 
is a sectional view showing the relationship between the upper anvil means 
62 and the lower anvil means 64. If the upper anvil means 62 were lowered 
to physically contact the lower anvil means 64 such contact would take 
place at three points A, B, and C. Of course during the formation of the 
bag pack 10, the upper and lower anvil means never physically contact each 
other. 
The practice of the present invention includes varying the size of the 
upper and lower anvil means as needed given the bag material and bag 
selected. For the arrangement shown in FIG. 7, the diameter of the upper 
anvil means may be about 145% that of each anvil of the anvils making up 
the lower anvil means. An upper anvil means of diameter 20.3 mm (0.800 in) 
used with three lower anvils of diameter 14 mm (0.550 in) has been found 
to be very effective in the practice of this invention. Use of such large 
diameter anvils to form a releasable fused region 54 is unprecedented in 
the prior art and provides many advantages as described herein below. It 
should be well understood that the anvil sizes stated herein are intended 
as non-limiting examples. It is well within the capability of a person of 
ordinary skill in the art to vary the configuration, number, and placement 
of upper and lower anvil means to achieve the proper releasable fused 
region 54 for a particular application. 
The scope of the present invention includes creating a gradually releasably 
adherent bond between bags in a bag pack by creating a suitable number of 
releasable fused regions 54 in as many locations as necessary to ensure 
the complete and efficient opening of a following bag in a bag pack by a 
leading bag thereof. In a particularly preferred bag pack 10, as is shown 
generally in FIG. 1 and in more detail in FIG. 5, the use of a first and 
second pair of anvil means 60 is required to form first and second 
releasable fused regions 54 within the corona discharge treated surface 
portions of the bag. The releasable fused regions are preferably located 
below the mouth 24 and handle 11 region of the bags. 
The dimples 56 within the releasable fused regions 54 have the same general 
configuration as the lower anvil means, i.e. three circles in tangential 
alignment. (See FIG. 5) However, the dimples are significantly different 
in that they are separated by a non-fused zone 59. It can be seen that 
despite the tangential contact between the anvils in the lower anvil 
means, the dimples formed thereby do not tangentially contact each other. 
Rather the dimples are closely spaced. (The dimples shown in FIG. 5 have 
been shown enlarged relative to the rest of the bag for clarity.) The 
releasable fused regions 54 therefore comprise fused zones and a non-fused 
zone. The fused zones are comprised by the dimples 56. The non-fused zone 
59 can be defined as any non-fused area bounded on either side by a fused 
zone. 
The combination of large dimple size and the presence of non-fused zones in 
the releasable fused region 54 provide exceptional performance in an easy 
open grocery bag pack. It has been observed that the separation of the 
back wall of a leading bag from the front wall of a following bag occurs 
gradually in a controlled fashion in the bag pack of the present 
invention. It has been observed that the fused portions of the bag walls 
gradually peel apart as the lead bag pulls open the following bag in a bag 
pack. This phenomenon can also be referred to as gradual linear separation 
because the bag walls separate along a horizontal line that travels from 
the top to the bottom of the releasable fused region 56. In contrast, 
prior art releasable connections such as that described in U.S. Pat. No. 
5,335,788 to Beasley separate all at once and tend to pop apart. In the 
practice of the Beasley patent, the entire bonded area of the releasable 
connection separates suddenly potentially detracting from bag opening 
performance. Moreover, the system disclosed in the Beasley patent is 
effective to open only the mouth area of the bag. The lower two-thirds of 
the bag body below the bag mouth is not opened. A grocery store attendant 
would still be faced with the additional, time-consuming task of manually 
opening the body of the bag by hand. 
The presence of the non-fused zone in the releasable fused region 54 of the 
present invention reduces the stresses created as the bags in a bag pack 
are separated. Moreover, the dimples 56 of the present invention provide a 
large area upon which to distribute the force necessary to form the 
releasably adherent connection. As a result, significantly less force is 
required to form the dimples and there is no significant deformation of 
the bag material. It follows that the bag pack releasable fused region 54 
can be formed with much less compression of the bag pack than is required 
by prior art methods. The imprint formed on the bag does not result in any 
weakening of the bag wall. The bag wall thickness in the dimple is 
substantially the same as the bag wall thickness outside of the dimple. 
This characteristic is particularly important to the successful use of 
multiple releasable fused regions 54 and affords a bag manufacturer more 
flexibility in placement of the releasable fused regions 54. Prior art 
techniques requiring a force of 5000 lbs or more to compress the stack 
face limitations in the numbers and placement of releasably adherent 
areas. 
The large surface area devoted the formation of the releasable fused region 
54 may also serve to compensate for any deficiencies in the operation of 
the associated manufacturing equipment. Prior art methods or bags using a 
releasably adherent area composed of a single bonding point or even a 
collection of widely space bonding points may suffer serious performance 
problems if such deficiencies are encountered. Increasing the number of 
prior art bonding points is not a desirable solution due to the above 
described tendency of prior art methods to weaken bag film material at the 
bonding points. In its preferred embodiment using three dimples, the 
present invention will function properly to provide a gradually releasable 
fused region even if a proper bond is not created in one of the dimples. 
It has been found that two of the three dimples will provide satisfactory 
opening performance. 
A preferred embodiment of the practice of the present invention is shown in 
the elevation view of a complete bag 80 in FIG. 8 where a four releasable 
fused regions 54 have been used. This preferred embodiment is about 30.5 
cm (12 in) wide and has an overall height of about 56 cm (22 in). The 
corona discharge treated region 82 is shown as the shaded area in FIG. 8. 
The region 82 is about 28 cm (11 in) wide and is centered from side to 
side on the bag. There is provided an upper pair of releasable fused 
regions 54a, 54a' and a corresponding lower pair, 54b, 54b'. The upper 
pair 54a, 54a' is positioned below the bag mouth with one region directly 
below each handle. The lower pair, 54b, 54b' is placed directly below the 
upper pair at a distance of about 5.08 cm (2 in). It has been found that 
this novel arrangement of gradually releasably bonded regions will open 
fully the entire body of the bag. 
It will be noted that the suspension orifices 84 are located at a midway 
position in the handles. This is important for the most efficient 
operation of the system of the present invention. Located midway permits 
the loop of the handles to spread open on suspension rods 14 as shown in 
FIG. 2. Spreading the handle loops in this manner opens the bag. If the 
bags were suspended from the handles from a point above the top seals of 
the handles, as taught by some prior art, the handle loops would not be 
able to spread open because the support rods would be remote from the 
loops. As indicated above, seconds and fractions of a second are extremely 
important when translated into the front end overhead costs of a 
supermarket. Any improvement which saves these short intervals of overhead 
expense is a significant advance in the art. The overall time saved by the 
present invention is considerable. 
FIG. 4 shows in plan view the operation and results of carrying out the 
process of FIG. 3 which culminates in the formation of bag pack 10. As may 
be seen, releasably fused regions 54 have been formed in the bags of bag 
pack 10. 
It is not fully understood why the corona discharge treatment and pressure 
technique results in the efficient automatic opening of a following bag in 
the subject system. Attention is, however, directed to the paper MECHANISM 
OF CORONA-INDUCED SELF-ADHESION 0F POLYETHYLENE FILM by D. K. Owens, 
Journal of Applied Polymer Science Vol. 19, pp. 265-271 (1975). In this 
paper it is postulated that the force of adhesion between corona-treated 
polyethylene films is a hydrogen bond between the hydrogens of enolized 
keto groups in one sheet of film and carbonyl groups in the other. The 
corona treatment across the front and back of each gusseted sack is 
believed to stimulate both the bonding and releasing effect created by the 
dimple design. 
Although the present invention has been described with preferred 
embodiments, it is to be understood that variations and modifications may 
be resorted to, without departing from the spirit and scope of the 
invention, as those skilled in the art will understand. Such modifications 
and variations are considered to be within the purview and scope of the 
appended claims.