BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] This invention relates to the manufacture and dispensing of plastic bags and more
particularly to.a manufacturing method and arrangement of multiple plastic bags from
which open bags are dispensed individually and which presents an conspicuous retrieval
point for each bag.
2. Description of the Related Art
[0002] Plastic bags have become the preferred means for packaging goods sold in shops and
markets throughout the world. As manufacturing techniques become more sophisticated,
bags have become extremely thin, complicating their storage, dispensing and use. Currently,
it is known to stack multiple thin film plastic bags and bond them together at one
or more points so that the assembled stack of bags can be stored and displayed neatly.
The bonded portions are typically not part of the bag itself but part of a bag root
from which each bag breaks away at perforations between the bag and bag root.
[0003] Typically, the consumer or clerk grasps any convenient portion of the bag and exerts
pulling force to break the perforations and separate a bag from the bag root. This
motion does not usually open the bag. The thin film from which bags are constructed
is inherently flimsy and prone to static charge. The limp nature of the film combined
with static charges cause the inner layers of the bag to cling together, making opening
of the bag inconvenient and time consuming. Frequently, opening the bag requires extensive
manipulation that potentially contaminates the bag. Additionally, the user frequently
grasps and retrieves more than one bag. This often results in unused bags being thrown
away.
[0004] There is a need' in the art for an arrangement for dispensing plastic bags which
is not only practical for transportation and display but also overcomes the inconveniences
associated with bag retrieval and opening as described above.
SUMMARY OF THE INVENTION
[0005] Briefly stated, a preferred embodiment of the invention comprises the manufacture
of a thin film plastic bag where the body of the bag is high-density polyethylene
(HDPE) with a strip of low-density polyethylene (LDPE) applied to a portion of front
and back outside surfaces of the bag. The LDPE has a lower melting point than the
HDPE. The invention then utilizes the different melting points to form an easily breakable
bond connecting the outside surfaces of adjacent bags in a stack. Thus, when a first
bag is retrieved from the stack of bags, it draws with it the front side of the following
bag while the bond to the next bag restrains the rear side. In this manner, the clerk
or consumer is always presented with an obvious and conveniently graspable portion
of an already open bag for retrieval. Physical manipulation, i.e., shaking, blowing
or rubbing is not required to open the bag, lowering the chances of contamination.
Bags are retrieved individually, overcoming the common problem in the prior art where
multiple bags are retrieved in error.
[0006] In accordance with a further aspect of the invention, a flexible separation tab is
attached to the stack of bags in a position to separate the front and back portions
of the top bag in the stack. The separation tab deflects from this position as the
top bag is retrieved, then moves back into place separating the front and back portions
of the following bag. The separation tab may be brightly colored to indicate a highly
visual and well defined retrieval point. Thus, a clearly delineated retrieval point
is presented, eliminating the grasping of multiple bags.
[0007] In accordance with another aspect of the invention, the inventive composite HDPE/LPDE
bag and bonding method may be applied to known hanging bag arrangements as well as
stacks of bags that are dispensed from a box or other container. In either configuration,
a clearly defined retrieval point is presented to the clerk/consumer and bags are
dispensed open and one at a time.
[0008] It is an object of the present invention to provide a new and improved plastic bag,
arrangement for dispensing plastic bags and manufacturing method for plastic bags
and plastic bag dispensing arrangements which ensure the dispensing of individual
bags that are open and ready for use.
[0009] Another object of the present invention is to provide a new and improved thin film
plastic bag that permits a stack of the bags to be assembled in which retrieval of
a bag opens the following bag.
[0010] A further object of the present invention is to provide a new and improved dispensing
arrangement of plastic bags which presents a clearly defined retrieval point to the
user.
[0011] These and other objects, features, and advantages of the invention will become readily
apparent to those skilled in the art upon reading the description of the preferred
embodiments, in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012]
Figure 1 is a front plan view of a hanging dispensing arrangement of bags in accordance
with the present invention;
Figure 2 is an exploded view of an arrangement of bags to be dispensed from an enclosure
in accordance with the present invention; and
Figure 3 is a sectional end view through one full bag and a partial second bag illustrating
the bond between outside bag layers in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] Referring more particularly to Figures 1 through 3, wherein like numerals refer to
similar parts, Figure 1 illustrates a hanging dispensing arrangement 10 of film bags
2 in accordance with the present invention. The bags 2 are primarily manufactured
from high-density polyethylene (HDPE). The HDPE preferably has a molecular weight
in the range of between .935 and .95. HDPE of this molecular weight will typically
have a softening/melting point in a range of from 135°C to 160°C. HDPE bags of conventional
thickness have proven to be practical for purposes of implementation of the present
invention.
[0014] In accordance with one aspect of the present invention, during extrusion of the bags
a layer of low-density polyethylene (LDPE) 1 Is applied to a portion of both primary
outside surfaces, i.e., the front and back outside surfaces of each film bag 2. The
LDPE preferably has a molecular weight in the range of approximately .92 or less.
LDPE having this molecular weight will typically have a softening/melting point in
the range of from 90°C to 105°C. The LDPE is preferably applied in a layer thickness
of less than .002mm and more preferably less than .001 mm.
[0015] The bags are manufactured using common extrusion and partial combination. These methods
of plastic bag manufacture are well known and understood by those of skill in the
art. During bag manufacture the LDPE is included during extrusion of the bag material.
The HDPE and LDPE are extruded at the same time. The LDPE material is then partially
combined on the outside of the HDPE bag material to form an external layer. At the
extrusion stage, the bag material may extruded as a tube or as a sheet. The LDPE is
preferably applied in a strip along a portion of the bag material that will be positioned
at the median of thefinished bags. Thus, in accordance with one aspect of the present
invention, when the bags are stacked and cut, the LDPE strip preferably coincides
with the center of the bag opening.
[0016] Figure 3 is a sectional view through one bag and a partial second bag. The bag body
2 is constructed of HDPE, which in this case is extruded as a tube. A strip of LDPE
1 is partially combined or bonded to opposite outside surfaces of the HDPE tube. The
tube is folded, cut and formed into bags as described herein. Heat is applied to form
a bond 7 between the external LDPE portions 1. The temperature applied is in a range
to partially melt the LDPE but is insufficient to soften or melt the HDPE bag body
2. The inside surfaces of the bag, being constructed of HDPE, remain free of each
other.
[0017] Individual bags 2 are cut from the extruded tube or formed from the sheet bag material
as is known in the art. The illustrated bags 2 are formed from an extruded tube of
bag material and are of the type having symmetrical handles on either side of an opening.
An area of the extruded tube above the opening and between the handles is utilized
as a bag root 4. In manufacturing steps, perforations 5 are. provided between the
bag root 4 and the bag 2, while a seal 16 is applied to the top of the handles and
the bottom of the bag. Some of the HDPE material is removed and recycled into additional
bags. Of course the invention as herein described is compatible with other bag configurations.
[0018] Melted through holes 6 connect all the bag roots 4. Individual bags 2 separate from
the connected bag roots at the perforations 5. The 'through holes 6 permit the dispensing
arrangement 10 to be hung in a convenient location for use by the consumer or clerk
as is currently known in the art.
[0019] Figure 1 illustrates a hanging arrangement for dispensing bags 2. In accordance with
one aspect of the present invention, the bags are stacked in multiples of approximately
50 to 300, although other smaller or larger stacks may be desirable. Heat and pressure
are applied to the stacked bags in a location corresponding to the LDPE film portion.
As an example: For a stack of 100 bags manufactured from HDPE film of .007mm thickness
with an LDPE layer of less than .001mm thickness, heat is applied by means of heated
pressure points disposed on opposite sides of the stack. The configuration and position
of the heated pressure points determines the configuration and position of the resulting
bond 7 between bag outside surfaces. A temperature of approximately 100°C is applied
for a period of approximately 30 seconds. As a result, a bond 7 is formed between
the LDPE layers joining only the outside surfaces of adjacent bags in the stack.
[0020] The bag bodies comprised of HDPE have a higher melting point than the LDPE layer.
As a result, while the outside surfaces of adjacent bags are joined, the inside surfaces
of. the bags remain separate. Further; the bond formed between the thin LDPE layers
on the outside surfaces of the bags is relatively weak. A thicker LDPE layer would
result in an undesirably robust bond. The LDPE layer is preferably less. than .002mm
in thickness and even more preferably less than .001mm. Thus, when a consumer or clerk
grasps a first bag, the inside surfaces separate easily. The front portion of a first
bag is retrieved by the user while the rear portion of the first bag is held back
via its connection 7 to the following bag. Each bag is opened in a reliable and predictable
manner. Further, during retrieval of a bag, the front portion of the following bag
is pulled away from the. rear layer.
[0021] In accordance with a further particular aspect of the invention, a flexible separation
tab 14 is arranged to maintain the separation between front and rear layers initiated
by retrieval of the previous bag. The separation tab 14 flexes out of the way while
a bag is being retrieved but falls back to maintain the separation between the layers
of the next bag in the stack. The separation tab 14 is preferably solid brightly colored
heavy gage polyethylene. The separation tab clearly indicates where the next bag is
to be grasped and retrieved. The top surface of the next bag will always be sequentially
separated from the stack by the separation tab 14. The separation tab 14 may be fixed
to the bag root (as illustrated), may be clipped on or otherwise arranged to remain
adjacent the bag opening.
[0022] Figure 2 illustrates an alternative dispensing arrangement 20 of bags configured
to be dispensed from a box or other container. The bags incorporated into this arrangement
are for all practical purposes identical to the bags described with respect to the
arrangement of Figure 1. The manufacturing of the bags 2 and formation of the bonds
7 between bags are carried out as described above with reference to the hanging dispensing
arrangement 10.
[0023] In the contained dispensing arrangement 20, the bag root 4 consists of portions adjacent
each handle and a portion adjacent the bag opening. The bags are formed and stacked
as described above. The bag root portions 4 are melted together. The thermal bond
7 is then formed as described above ' with reference to hanging dispensing arrangement
10. The. thermal bond 7 joins the outside surfaces of adjacent bags as previously
discussed. In the illustrated embodiment, the stacked, bonded bags are arranged on
and fixed to a rigid baseboard 9 by the bag roots 4. Perforations 5 are provided between
the bag roots and the bags themselves. Other bag dispensing configurations that may
include other LDPE layer configurations. may to one of skill in the art. The illustrated
embodiments are given by way of illustration only and are not intended to limit the
invention disclosed herein.
[0024] The stacked bonded bags and baseboard 9 are inserted into a box, plastic sack 11
or other container having an opening 12. The opening 12 is arranged so that a retrieval
portion 8 of the top bag protrudes from the opening. The container may be a permanently
mounted, re-fillable dispenser (not illustrated). The clerk or consumer grasps the
retrieval portion 8 to retrieve a bag. The bond 7 between outside layers of the bags
restrains the rear portion of the bag being retrieved. This forces the bag to open
while being retrieved. Each bag separates from the bag roots 4 along perforations
5. The bond 7 pulls the next retrieval portion 8 through the opening breaking the
first perforations 5 adjacent the upper central bag root 4.
[0025] In this illustrated embodiment 20 and in accordance with another aspect of the present
invention, the connection between bag 2 and root 4 formed by perforations 5 adjacent
the upper central bag route is preferably less robust than the connection between
bag 2 and root portions formed by perforations adjacent the handle bag roots 4. The
thermal bond 7 between adjacent bag outside layers thus is strong enough to break
the perforation at the upper central bag root and pull the next retrieval portion
8 through the opening before the bag connections to the handle roots restrain the
bag and break the bond 7. Only the bag being retrieved is touched or exposed to the
atmosphere. This arrangement maintains the stacked bags neatly and in a clean environment.
[0026] The strength of the thermal bond 7 and the connections formed by the perforations
can be adjusted as necessary to provide a desired bag-opening and tear off properties
for a given bag dispensing arrangement. Thermal bonds having a larger surface area
will be stronger than thermal bonds having a smaller surface area. Multiple bonds
are stronger than single bonds. Perforated connections in which the webs of bag material
between perforations are smaller will be weaker than perforated connections in which
the webs of bag material are more substantial. Also, the thickness of the bag film
and thickness of the low melting point layer will affect the strength of the thermal
bond and perforated connections.
[0027] A preferred embodiment of extruded HDPE bag with LDPE partial layer has been disclosed.
It will occur to those skilled in the art that other bag materials might utilize the
principles of the present invention. For example, a polypropylene bag material with
a layer of LDPE may prove to be a practical embodiment of the invention. Other polymer
films or sheet materials may also be applicable.
[0028] While preferred embodiments of the foregoing invention have been set forth for purposes
of illustration, the foregoing description should not be deemed a limitation of the
invention herein. Accordingly, various modifications, adaptations and alternatives
may occur to one skilled in the art without departing from the spirit and the scope
of the present invention.
1. A plastic bag comprising:
a bag body constructed from a first plastic film having a first melting temperature,
said bag body having front and back outside and inside surfaces; and
a layer of a second plastic film having a second melting temperature,
wherein said layer is deposited on said front and rear outside surfaces and said
second melting temperature is lower than said first melting temperature.
2. The plastic bag of claim 1, wherein said layer is deposited on a portion of said front
and rear outside surfaces.
3. The plastic bag of claim 1, wherein said layer is deposited along a median of said
bag body front and rear outside surfaces.
4. The plastic bag of claim 1, wherein said first plastic film is high-density polyethylene
(HDPE) and said second plastic film is low-density polyethylene (LDPE).
5. A method of manufacturing a dispensing arrangement of plastic. bags, each said bag
having an inside surface comprising a first material having a first melting temperature
and an outside surface at least partially comprising a second material having a second
melting temperature, said second melting temperature being lower than said first melting
temperature, said method comprising the steps of:
arranging a plurality of said bags in a stack with the outside surfaces of each bag
in contact with the outside surfaces of a preceding and a subsequent bag;
applying heat and pressure to said stack, said heat and pressure sufficient to form
a bond between the outside surfaces of adjacent bags without forming a bond between
the inside surfaces of any bags in the stack.
6. The method of claim 5, wherein wheat of approximately 100°C is applied by means of
a heated element.
7. The method of claim 6, wherein said heated element applies a constant pressure to
said stack.
8. A dispensing arrangement of plastic bags having inside and outside surfaces, said
dispensing arrangement comprising:
a plurality of said plastic bags disposed in a stack with said outside surfaces in
contact with each other,
wherein the outside surfaces of adjacent bags in said stack are bonded together
at a first location and said inside surfaces are not bonded together at said first
location.
9. The dispensing arrangement of claim 8, wherein each bag in said arrangement includes
an open end and a closed end and said first location is adjacent said open end.
10. The dispensing arrangement of claim 9, wherein each bag in said arrangement comprises
a bag root connected to said open end by a perforated attachment and said bag roots
are connected to each other, said arrangement further comprising:
a separation tab configured to project into the open end of a top bag in said stack.
11. The dispensing arrangement of claim 10, wherein said separation tab is resiliently
flexible, such that said separation tab deflects during disconnection of said top
bag from said stack and returns to a position projecting into the open end of a top
bag in said stack.
12. The dispensing arrangement of claim 8, wherein said plurality of plastic bags are
surrounded by a container, said container having an opening through which a retrieval
portion of a top bag in the stack protrudes, said opening and said bond configured
such that withdrawal of said top bag pulls a retrieval portion through said opening
after which said bond breaks.
13. A method for manufacturing a plastic bag comprising the steps of:
providing a bag body constructed of a first plastic film having a first melting temperature,
said bag body having inside and outside surfaces; and
bonding a layer of a second plastic having a second melting temperature to the outside
surface of said bag body,
wherein said second melting temperature is lower than said first melting temperature.
14. The method of claim 13, wherein said step of providing comprises extruding said bag
body from HDPE and said step of bonding comprises partial recombination of said second
layer comprising LDPE to the outside surface of said bag body.
15. The method of claim 13, wherein said step of bonding comprises bonding a layer to
only a portion of said outside surface.
16. The method of claim 13, wherein said step of bonding comprises bonding a strip of
LDPE to opposite portions of said outside surface.