U.S. patent application number 09/808572 was filed with the patent office on 2002-09-19 for plastic trash bag with odor control and method of making.
Invention is credited to Franzen, Richard J., Hughes, Paul C., Lorang, Kevin M..
Application Number | 20020132070 09/808572 |
Document ID | / |
Family ID | 25199139 |
Filed Date | 2002-09-19 |
United States Patent
Application |
20020132070 |
Kind Code |
A1 |
Franzen, Richard J. ; et
al. |
September 19, 2002 |
Plastic trash bag with odor control and method of making
Abstract
A plastic trash bag with odor control is formed of a bag having
a pair of opposed sides joined together along longitudinal edges
and at one end, the bag being longitudinally folded such that one
bag side defines a pair of adjacent facing surfaces. A generally
uniform dusting of odor-absorbing particles is disposed on at least
the adjacent facing surfaces.
Inventors: |
Franzen, Richard J.; (St.
Paul, MN) ; Hughes, Paul C.; (Bossier City, LA)
; Lorang, Kevin M.; (Victoria, TX) |
Correspondence
Address: |
Neal L. Rosenberg, Esq.
AMSTER, ROTHSTEIN & EBENSTEIN
90 Park Avenue
New York
NY
10016
US
|
Family ID: |
25199139 |
Appl. No.: |
09/808572 |
Filed: |
March 14, 2001 |
Current U.S.
Class: |
428/35.2 ;
427/180 |
Current CPC
Class: |
B65F 7/00 20130101; B65F
1/0006 20130101; B65F 2210/102 20130101; Y10T 428/1334
20150115 |
Class at
Publication: |
428/35.2 ;
427/180 |
International
Class: |
B65D 001/00 |
Claims
I claim:
1. A plastic trash bag comprising: (A) a bag having a pair of
opposed sides joined together along longitudinal edges and at one
end, said bag being longitudinally folded such that one bag side
defines a pair of adjacent facing surfaces; and (B) a generally
uniform dusting of odor-absorbing particles on said adjacent facing
surfaces.
2. The bag of claim 1 wherein the other bag side is relatively free
of said odor-absorbing particles.
3. The bag of claim 1 wherein the other bag side defines a pair of
oppositely facing surfaces, and a generally uniform dusting of
odor-absorbing particles is also disposed on said oppositely facing
surfaces.
4. The bag of claim 1 wherein said odor-absorbing particles are
baking soda (sodium bicarbonate) particles.
5. The bag of claim 1 wherein said odor-absorbing particles are
baking soda particles mixed with a relatively small quantity of a
flow-control additive.
6. The bag of claim 1 wherein said bag is polyethylene.
7. The bag of claim 1 wherein said bag is polyethylene having a
relatively small quantity of odor-absorbing material therein.
8. A plastic trash bag comprising: (A) a polyethylene bag having a
pair of opposed sides joined together along longitudinal edges and
at one end, said bag being longitudinally folded such that one bag
side defines a pair of adjacent facing surfaces; and (B) a
generally uniform dusting of odor-absorbing baking soda particles
on said adjacent facing surfaces, the other bag side being
relatively free of said odor-absorbing particles.
9. A method of making a plastic trash bag in the form of a
longitudinally folded flat tubular web sealed at one end, the
method including the step of applying, prior to longitudinal
folding of the bag, a generally uniform dusting of odor-absorbing
particles to one of the bag sides which will define a pair of
adjacent facing surfaces after longitudinal folding of the bag.
10. The method of claim 9 wherein the uniform dusting is applied
immediately prior to longitudinal folding of the bag.
11. The method of claim 9 wherein, after application of the uniform
dusting, the bag is longitudinally folded and sealed at one
end.
12. The method of claim 9 wherein the uniform dusting is applied
electrostatically.
13. The method of claim 9 wherein the uniform dusting is applied to
only the one of the bag sides.
14. The method of claim 9 wherein the odor-absorbing particles are
baking soda (sodium bicarbonate) particles.
15. The method of claim 9 wherein the odor-absorbing particles are
baking soda particles mixed with a relatively small quantity of a
flow-control additive.
16. The method of claim 9 wherein the bag is polyethylene.
17. The method of claim 9 wherein the bag is polyethylene having a
relatively small quantity of odor-absorbing material therein.
18. A method of making a plastic trash bag in the form of a
longitudinally folded flat tubular web of polyethylene sealed at
one end, the method including the step of electrostatically
applying, immediately prior to longitudinal folding of the bag, a
generally uniform dusting of odor-absorbing baking soda particles
to only the one of the bag sides which will define a pair of
adjacent facing surfaces after longitudinal folding of the bag.
19. The method of claim 18 wherein a generally uniform dusting of
odor-absorbing particles is applied to exposed surfaces of the bag
subsequent to longitudinal folding of the bag.
20. A wrap comprising a plastic film having on at least one surface
thereof a generally uniform dusting of odor-absorbing baking soda
particles.
21. The wrap of claim 20 wherein said film has said dusting on each
surface thereof.
22. The wrap of claim 20 wherein said film has said dusting on only
one surface thereof.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to plastic trash bags, and
more particularly a plastic trash bag provided with odor control
enhancements and a method of making a plastic trash bag with odor
control enhancements.
[0002] Typically, plastic trash bags are formed by extruding a
continuous tube of polyethylene plastic, from a molten source of a
heated polyethylene blend, to form a "bubble" of polyethylene. The
bubble is then cooled and collapsed to form a flat web of
overlapping plies. The tubular envelope and web are continuously
moved along a path from the extruder until the individual bags are
sealed, perforated or severed, rolled and packaged.
[0003] There is a widespread belief in the plastic trash bag
industry that the user or consumer of plastic trash bags considers
the odor associated with trash bags and their use to be an
undesirable characteristic. Obviously, odors may arise from a
number of possible sources associated with plastic trash bags, such
as the contents of the bag, the polyethylene material used to
manufacture the bag, and residual matter on the inside of a can or
container lined by the trash bag. Residual matter may not have been
cleaned from the container after prior use.
[0004] One attempt to alleviate consumer dissatisfaction with odors
associated with trash bags involved introducing substances carrying
a perfumed scent into the polyethylene formulation from which the
trash bags are extruded. These attempts merely mask the odor; they
do not reduce the concentration or intensity of the odor. Such
solutions typically require that the manufacturer provide a variety
of different scents in order to meet consumer preferences. Even
when scented material is present, it will mask primarily odors
emanating from substances within the bag and, if the odor is
produced by an unclean can, for example, scented bags may have less
effectiveness in masking odors.
SUMMARY OF THE INVENTION
[0005] The present invention contemplates applying a generally
uniform dusting of baking soda (sodium bicarbonate) or like
odor-absorbing particles on at least the exterior surface of a
tubular web of polyethylene or similar plastic during the process
of manufacturing the bag. The baking soda is preferably applied by
deposition from an electrostatic sprayer. The baking soda
substantially uniformly coats at least one surface of the web prior
to folding of the web longitudinally with the two coated
half-surfaces adjacent and facing each other. The coated, folded
web is then sealed, perforated and wound onto a roll or packed
singly.
[0006] By applying the baking soda to one surface of the web and
then folding the web before subsequent processing, the baking soda
remains as a topical coating on what eventually will be a portion
of the exterior surface of the bag. Subsequent processing--for
example, pulling via nip rolls, supporting the web with fixed bars
or rollers, sealing and perforating--does not disturb the baking
soda because the baking soda coating is sandwiched between and
protected by the longitudinally folded sides of the web. Thus, when
the bag is unfolded for use, the baking soda is still present on a
portion of the exterior surface of the bag. The baking soda is
effective primarily to absorb and thereby reduce odors emanating
from within the container in which the bag is placed for use and
from the bag material itself. By applying the baking soda to both
exterior surfaces of the web and then folding the web, the baking
soda is not disturbed on a portion of the exterior surface of the
bag, although it may be slightly disturbed on the other
portion.
[0007] Moreover, one embodiment of the present invention
contemplates incorporating odor-absorbing materials within the
blend of polyethylene prior to extrusion of the tubular web. These
chemicals are capable of absorbing, and therefore controlling,
odors emanating from the contents within the bag. The combination
of the exterior baking soda and odor-absorbing ingredients within
the bag material cooperate to produce an effective overall
reduction of unpleasant odors associated with a plastic trash bag
and its use.
[0008] More particularly, the present invention encompasses a
plastic trash bag comprising a bag having a pair of opposed sides
joined together along longitudinal edges and at one end, the bag
being longitudinally folded such that one bag side defines a pair
of adjacent facing surfaces. A generally uniform dusting of
odor-absorbing particles is disposed on the adjacent facing
surfaces.
[0009] The other bag side is either relatively free of the
odor-absorbing particles or defines a pair of oppositely facing
surfaces, with a generally uniform dusting of odor-absorbing
particles also being disposed on the oppositely facing surfaces. In
a preferred embodiment, the odor-absorbing particles are baking
soda (sodium bicarbonate) particles, preferably mixed with a
relatively small quantity of a flow-control additive, and the bag
is polyethylene, preferably polyethylene having a relatively small
quantity of odor-absorbing material therein.
[0010] The present invention further encompasses a method of making
a plastic trash bag in the form of a longitudinally folded flat
tubular web sealed at one end. The method includes the step of
applying, prior to longitudinal folding of the bag, a generally
uniform dusting of odor-absorbing particles to one of the bag sides
which will define a pair of adjacent facing surfaces after
longitudinal folding of the bag.
[0011] In a preferred embodiment, the uniform dusting is applied
immediately prior to longitudinal folding of the bag, and, after
application of the uniform dusting, the bag is longitudinally
folded and sealed at one end. The uniform dusting is applied
electrostatically, preferably to only the one of the bag sides.
BRIEF DESCRIPTION OF THE DRAWING
[0012] The above and related object, features and advantages of the
present invention will be more fully understood by reference to the
following detailed description of the presently preferred, albeit
illustrative, embodiments of the present invention when taken in
conjunction with the accompanying drawing wherein:
[0013] FIG. 1 is a diagrammatic or schematic view of a plastic bag
manufacturing line for practice of the present invention;
[0014] FIG. 2 is a diagrammatic view of an electrostatic spray
applicator for applying baking soda to the moving web, as seen in
FIG. 1; and
[0015] FIG. 3 is a fragmentary diagrammatic or schematic view of an
alternative plastic bag manufacturing line for practice of the
present invention.
[0016] Like reference numerals will be used to refer to like parts
in the various views.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
[0017] Referring to FIG. 1, there is shown, partially in
diagrammatic or schematic form, apparatus for making plastic bags,
the apparatus being commonly referred to in the industry as a
"blown film line." Such facilities are large and typically rest on
a floor, as represented by the horizontal line 10. The drawing of
the blown film line of FIG. 1 includes only those principal parts
to which reference need be made to understand the present
invention. Moreover, except for the baking soda applicator
incorporated into the blown film line and specifically illustrated
in FIG. 2, the apparatus shown in FIG. 1 is otherwise conventional
and known to persons skilled in this art. Thus, a more detailed
description of the structure and components of the apparatus such
as a drive motor, controls, transmission, etc. need not be given
for an understanding of the present invention by those skilled in
the art.
[0018] Hopper 11 contains a blend of polyethylene material and
suitable additives out of which the bags are made. Conventional LLD
(linear low density) polyethylene material, including conventional
coloring concentrates, slip and calcium carbonate in known
quantities and percentages, provide the basic blend. To this
mixture is added, in the preferred embodiment of the present
invention, an odor-absorbing material in the range of 2-6 percent
by weight of the combined polyethylene blend. A suitable
odor-absorbing additive is molecular sieves known as gas absorber
concentrate, and in particular, a product available under the
tradename GAG-1000-3 from Polyfil Corp. of Rockaway, N.J. Another
suitable odor-absorbing additive is available under the tradename
Code PM 111 76E4 from Techmer PM of Rancho Dominguez, Calif.
[0019] The blend is fed from hopper 11 into a horizontal extruder
12, where it is heated to approximately 400.degree. F. From the
extruder 12, the molten blend is forced through a vertically
elongated die 13 which forms the molten material into a continuous
tube of closed cross-section about a core of compressed air. Then
the tube is passed through an air ring which forces chilled air
onto the exterior of the tube.
[0020] After the polyethylene tube exits the vertically elongated
die, it forms a continuous enlarged cylindrical structure referred
to as a "bubble" in the industry. The bubble is formed and expanded
by compressed air. As the polyethylene tube travels vertically in
the form of a cylindrical bubble, the polyethylene material cools
and increases in rigidity and strength. The polyethylene tube
continues to travel at a constant speed and constant tension,
driven by a set of primary nip rolls (and other nip rolls which are
controlled to follow the primary nip rolls) to maintain a constant
tension on the material throughout the process (nip rolls not
shown).
[0021] The polyethylene tube then enters a device 20 referred to in
the industry as an "A-frame structure." The A-frame 20 includes
opposed first and second side planar members which are open at the
base to receive the bubble and then converge inwardly in the form
of an "A" to form a narrow exit slot at the top. The polyethylene
tube, as it moves upwardly, eventually contacts the opposing inner
surfaces of the side members of the A-frame. The side members
thereupon transition the cylindrical cross-section of the tube
initially to an elliptical shape and cross-section, and eventually
to a planar shape, collapsing the tube to a flat web configuration
comprising two overlying, contacting plies. The collapsed web-like
tube exists the A-frame 20, being pulled by the pair of primary nip
rolls.
[0022] Eventually, the web enters a folding frame 50 which folds
the web longitudinally--that is, so that the edges of the flattened
web are brought to overlie one another, creating a four-ply web
with a first lateral edge formed by the two original edges of the
two-ply web and a second lateral edge which is the folded
longitudinal centerline of the original two-ply web.
[0023] After leaving the folding frame 50, the web enters a second
or exit set of nip rolls (not shown) preceded by a
tension-maintaining apparatus (not shown) which maintains a
substantially constant tension on the web between the primary nip
rolls and the exit nip rolls.
[0024] After the web leaves the exit nip rolls, it passes through a
bag machine 60 which applies the bottom seal (or "heat weld") by
means of a heated bar on a rotating cylinder, as is generally
known. As the heat seal is applied to the web after it is
longitudinally folded, it produces a heat welding of the gathered
bag material. Thus, the web comprises four overlapping plies when
the heat weld is applied. This produces a bag bottom which has a
so-called "flat bottom" configuration. A perforation (providing a
tear line between adjacent bags) is also provided before the web
leaves the bag machine 60.
[0025] The web then passes through a winder 70 where it is wound
into a coreless roll. The rolls are then removed from or ejected by
the winder, and placed into a carton or a sleeve for packaging.
Alternatively, the web may be wound on cores, if desired.
[0026] As earlier indicated, the "blown film line" as described
hereinabove is conventional in the art for production of a flat
bottom bag.
[0027] The "blown film line" is also conventional in the art for
production of a bag with a "star bottom" configuration which is
believed to provide a greater strength in the bottom of the bag and
a more uniform, reliable seal than the flat bottom configuration.
The blown film line is substantially as described above except
that, as the bubble travels through the A-frame structure 20, the
bubble also travels over opposing gusset boards which fold the
lateral sides of the bubble inward to form two facing (almost
contacting) gussets. Thus, instead of a flat web configuration
comprising two overlying contacting plies, the tube leaving the
A-frame 20 comprises four overlying contacting plies, the two
additional tube plies being formed by the gusset folds. The web is
folded over once more by the folding frame 50 to create an
eight-ply web instead of the four-ply web described above. While
the gusset folds are clearly exterior surfaces of the bag when the
bag is in use and typically form 50% of the exterior surface of the
bag in use (excluding the bottom), during the travel of the bag
along the blown film line the gussets are "hidden" by the exterior
surface of the bag and may be ignored for the purposes of the
present invention. Accordingly, the present invention will be
described hereinbelow in the context of a flat bottom bag, although
clearly the principles thereof are equally applicable to a star
bottom bag.
[0028] According to one preferred embodiment of the present
invention, prior to entering the folding frame 50, the web passes
an applicator 40, to be described further below, which applies
particulate sodium bicarbonate (NaHCO.sub.3, commonly called
"baking soda") in the form of dispersed individual particles shown
at 43, to one surface of the double-ply web, in the region
designated 42, but only on the side of the web adjacent the
applicator 40. The one surface of the double-ply web is coated with
baking soda particles substantially uniformly and completely.
Thereafter, the web is folded longitudinally in the folding frame
50, as described above, so that the coated half-surfaces are facing
and the baking soda particles thereon will not be disturbed (e.g.
removed) by further processing.
[0029] Sufficient coating of the web with baking soda may be
achieved by placing the applicator 40 further upstream of the
folding frame 50, but it is preferred to locate the applicator 40
immediately upstream of, and adjacent to, the folding frame 50, as
illustrated. The reason for this is to avoid having the baking
soda-coated surface of the web contact any guide roller or pass
through nip rollers. Any contact with rollers may create a tendency
to deposit the baking soda on the rollers, and, because of its
nature, the baking soda would tend to cake and obstruct the free
movement of the web through such rollers. By folding the web
immediately after applying the baking soda thereto, the uniformity
of the applied coat is maintained, even though the web may undergo
subsequent handling or processing. In particular, contact between
the baking soda and rollers is avoided in this manner.
[0030] On the other hand, it is also advantageous to apply the
baking soda to the web shortly after it is cooled (for example,
while it is still about 120.degree. F.) so that the baking soda
particles become "stuck" on the warm bag and thus are less likely
to become dislodged therefrom by subsequent processing of the web.
Optimum placement of the applicator 40 downstream of the A-frame 20
and upstream of the folding frame 50 may be empirically determined
for any given blown film line with a minimum of routine
experimentation.
[0031] Referring now to FIG. 3, where it is not necessary to form a
bottom of the bag by first folding the web and then heat-welding
the bottom, the bottom of the bag material may be heat-welded (and,
if desired, perforated) in a bag machine 60A before entering the
folding frame 50A, in which case the applicator 40A is preferably
still placed immediately upstream of the folding frame 50A, but in
this example downstream of the welding and perforating operation
sites of the bag machine 60A.
[0032] Where deposition of the baking soda on the rollers is not
deemed to be problematic, the baking soda may be applied to both
surfaces of the double-ply web. This may be done by use of a single
applicator 40 positioned to distribute the baking soda
substantially uniformly and completely on both surfaces of the
double-ply web or by use of two applicators, the applicator 40 as
described hereinabove and a second like applicator 40' (indicated
in phantom line in FIG. 1) for substantially uniformly and
completely coating with baking soda the opposite surface of the
double-ply web. This applicator 40' applies the particulate sodium
bicarbonate in the form of dispersed individual particulates to the
opposite surface of the double-ply web, so that both surfaces of
the double-ply web become substantially uniformly and completely
coated with baking soda particulates.
[0033] In those instances where the possible adverse effects of
contact between the rollers and the baking soda are not
anticipated--that is, there is no adverse effect on the rollers due
to the deposition of baking soda thereon from the web and there is
no disturbance of the uniform and complete coating of the baking
soda on the web by contact with the rollers--the applicator 40 or
applicators 40, 40' may be located anywhere after formation of the
double-ply web. However preferably the applicator 40 is disposed
immediately prior to the folding frame 50, and the applicator 40'
is disposed immediately prior to the bag machine 60 or, as
illustrated, winder 70. Preferably applicator 40' is downstream of
applicator 40 and preferably downstream from as much as possible of
the blown film line equipment as possible. Applicator 40' is
illustrated in FIG. 1 as being disposed after the folding frame 50
and bag machine 60 and just before the winder 70.
[0034] While a single applicator 40 may be used to apply the baking
soda simultaneously to both exposed surfaces of the double-ply web,
preferably a pair of applicators 40, 40' are used, one deployed on
either side of the moving web, one upstream of the other.
[0035] Where desired, baking soda may also be applied to the
interior of the bag to assist in neutralization of odors emanating
from the materials placed within the bag.
[0036] The baking soda is suitably applied to the web by an
electrostatic sprayer to be described further below. The advantages
of using an electrostatic applicator are that the particles of
baking soda are uniformly dispersed and therefore applied in a more
uniform coating. Further, the electrostatically charged particles
have a greater tendency to adhere to the polyethylene material of
the bag due to the electrostatic attraction force.
[0037] Turning now to FIG. 2, one form of applicator 40 is shown.
The applicator of FIG. 2 is referred to in the industry as an
"electrostatic sprayer," and it is commercially available under the
tradename Series 500 Electrostatic Sprayer from Oxy-Dry Corporation
of Itasca, Ill. The applicator 40 includes an enclosed hopper or
housing 54 which provides a hopper for a supply of the baking soda
powder. Bridging or caking of the powder within housing 54 is
prevented by an internal air blower (not shown). An etched roller
55 is mounted within the housing 54 and driven by a motor (not
shown) to rotate in a clockwise direction.
[0038] The surface of the roller 55 is etched to form a series of
spaced pockets or cells of uniform size and spacing. The cells pass
beneath the supply of baking soda powder in hopper 54 as the roller
55 rotates and becomes filled with baking soda. A doctor blade (not
shown) removes excess powder from the cells as the roller 55
rotates. Thus, the etched roller 55 accurately meters the delivery
of baking soda. The interior of the housing 54 is pressurized and
provides air flow, referred to as an "air curtain," to assist in
delivering the powder to the desired area 42 of the moving web.
[0039] As the roller 55 rotates, it passes by a tube 57, referred
to as a "blast-off" tube, which applies an electrostatic charge to
the powder in the etched cells. The powder is then delivered from
the roller 55 as a stream of separated, charged particles 43,
attracted to the moving web by the electrostatic charge. The
particles 43 are deposited on the web in an uniform coating, and
they adhere to the web due to the electrostatic charge.
[0040] As the roller 55 continues to rotate, it passes a second
tube 59 which forces pressurized air against the surface of the
roller 55 to remove any residual powder and thereby prevent
build-up of powder on the surface of the roller 55.
[0041] A suitable baking soda for use with the electrostatic
sprayer is available under the tradename Product Code 3DF Baking
Soda from Church & Dwight Corporation. Preferably 0.5-3.0
percent fumed silica is added as a flow control additive. A
suitable flow control additive is available under the tradename
Product Code TS-610 Treated Fumed Silica from Cabot
Corporation.
[0042] While electrostatic applicators are preferred, clearly
non-electrostatic applicators may alternatively be used in the
practice of the present invention.
[0043] While the principles of the present invention have been
shown and described in connection with the formation of a bag by
the "bubble" technique, clearly the principles of the present
invention may be applied as well to bags formed by other techniques
as well. Thus, the principles apply to bags formed by the "cast"
technique, wherein a flat sheet of plastic material is laid out,
folded longitudinally, and the edges then welded shut to form a
web. The web is subsequently passed through a folding frame, a bag
machine and a winder. Use of the cast technique facilitates the
application of the baking soda to the interior of bag (prior to the
longitudinal folding of the sheet of plastic material and the
subsequent welding of the longitudinal edges) as well as the
application of the baking soda to the exterior of the bag.
Manufacture of a bag by the cast technique is conventional in the
art and, accordingly, need not be described herein in further
detail.
[0044] While the principles of the present invention have been
expounded above with regard to plastic trash bags, clearly they are
also applicable to plastic films (not bags) of the type
conventionally used to wrap articles such as foods. The film is
preferably polyethylene, polypropylene or polystyrene. Depending
upon the particular articles to be wrapped, a generally uniform
dusting of the baking soda particles is disposed on a surface of
the film (the surface facing the article, the surface facing away
from the article, or both). When the article is a foodstuff,
preferably the dusting is disposed only on one surface of the
film.
[0045] Now that the preferred embodiments of the present invention
have been shown and described in detail, various modifications and
improvements thereon will become readily apparent to those skilled
in the art. the spirit and scope of the present invention is to be
construed broadly and limited only by the appended claims, and not
by the foregoing specification.
* * * * *