Note: Descriptions are shown in the official language in which they were submitted.
W096l02439 P~,u~ .. "~
~ ~9~
FLEXIBLE BARRIER MEMBER USEFUL IN AEROSOL DISPENSERS
5This application is a continuation-in-part of United
States Patent Application Serial No. 08~253,143, filed June 2,
1994, titled "Flexible Barrier Member Useful In Aerosol
Dispensers", which in turn is a cnntinn7tion-in-part of United
States Patent Application Serial No. 08~084,638, filed June
1029, l9g3, titled "Flexible Barrier Member Useful In Aerosol
Dispensers."
Backqround of the Invention
1. Field of the Invention
15This invention relates to pressurized dispenser
packages, such as aerosol pa~k~g~, wherein the product to be
dispensed and the pressure-generating media, i.e. the
propellant, are ~;ntainPd in isolation through separation on
opposite sides of a barrier. An aerosol package of this type
20is generally referred to as a "barrier pack" aerosol package.
2. Descri~tion of the Prior Art
Aerosol barrier packs of the prior art have been of
at least three general types. In the piston-type barrier pack
25the barrier is a piston-like ~u nnPnt that is mounted in the
container in sliding relation to the inside surface of the
container. The product to be dispensed is disposed on the
valved side of the piston and the propellant, which generates
pressure within the container, is on the opposite side of the
W0 96~0243g !~ r~ 4
2195~~~
piston. In Aerosol Handbook, Second Edition, 19~32, there is
described a piston-type aerosol dispenser marketed by American
Can Company under the trade-name nMira-Flo". In the Mira-Flo
dlspenser the piston skirt is designed to seal against the
sides of the container to prevent the propellant gas from
passing into the product chamber on the other side of the
piston. Actuation of the aerosol discharge valve causes a
reduction in pressure in the product cha~ber thereby resulting
in the pressure in the propellant chamber urging the piston
toward the discharge valve and causing the discharge of
product through the discharge valve. Examples of a piston-typc
barrier pack are described in United States Patent Nos.
3,022,923, 3,756,476 and 3,929,132.
In a second type of aerosol barrier pack, a flexible,
collapsible bag is affixed within the ~nt~;nPr opening either
to the aerosol discharge valve or to the bead of the container
opening. The Con~;n~nt~l Can Company in the late 1960's
introduced an aerosol barrier dispenser known as the "Sepro-
Can~. The Sepro-Can includes an interior plastic product bag
having an opening that is attached to the valve opening at the
top of the container. The side walls of the bag extend along
the side walls of the container and are pleated like an
accordion 90 the bag can collapse inward and upward under the
influence of pressure in the rc-~;n~Pn of the container as the
bag is emptied. Patents which illustrate a barrier paok of
the second type are set forth in U.S. Patent Nos. 3,7a8,521,
3,896,g70 and 4,067,49g. Modifications of barrier packs of
the second type include attaching the bag to the siùe wall of
WO9G/0243g 219 5 4 ~ a4
.
-- 3
the container or to the joint formed between the side wall of
the container and the top of the container.
A third type of prior art barrier pack is an unfolding
cup-shaped barrier wherein the barrier has an outer wall
terminating in a sealing flange, said outer wall being
disposed contiguous to the inner wall of the container. The
inner wall of the barrier is initially folded withir. the outer
wall, the inner wall terminating in an end closing portion.
The barrier is contained in a valved aerosol container and
sealed at the joint formed between the sidewall and the bottom
end closure of the container. Product is admitted through the
valved opening of the container and propellant through a port
in the bottom end closure of the ~n~;n~r. Actuation of the
valve reduces the pressure in the product compartment and
results in the inner wall of the barrier unfolding from within
the outer wall of the barrier and causing the end-closing
portion of the inner wall of the barrier to advance and
thereby urge the product toward the discharge valve. A patent
which illustrates the third type of prior art barrier pack is
U.S. Patent No. 3,109,463.
A problem with the piston-type barrier pack of the first
type is the imperfect seal between the side skirt of the
piston and the side wall of the container which allows
propellant to seep into the product with consequent discharge
of propellant during product discharge as well as
contamination of the product with propellant. Also, it is not
uncommon for aerosol containers to be dented and thus lose
their true circumferential shape, with the consequence that
~v096/0~39 ~ PCT~S9~97~
~195~0~ ~
-- 4
the piston is incapable of axial movement within the container
past the aberrant configuration.
A problem with barrier packs of the second type wherein
the barrier is affixed to the valve or valve opening of the
container is that the barrier collapses in a manner to cause
pocketirg of the product within the collapsible barrier with
consequent undesirable diminution of the evacuatior. of the
product from the container.
Ir. the third type of prior art barrier pack described
0 hereir., the unfolding cup-shape barrier does not advance
progressively and uniformly against the inner wall of the
c~n~iner but tends to pocket and entrap product against the
wall or within pockets formed in the barrier itself as it
unfolds Attempts to solve these problems have included
adding an additional rigid piston to the end-closing portion
of the inner wall, or adhering the outer wall of the barrier
in peelable fashion to the inner wall of the cnn~in~r.
Generally, barriers of the third type can be difficult to
form, as well as to insert into and seal with the container.
There is, therefore, a need for a flexible
product/propellant barrier for an aerosol container that is
easy to manufacture and ship, that is easy to insert into and
seal to the container, that prevents leakage of the fluids
from one compartment to the other compartment, and that does
no~ pocket and therefore preclude evacuation of significant
amounts of the product to be discharged
WO96102~39 ~ Q j- r~u.,,.,~"~4
-- 5
SummarY of the Invention
The present invention relates to an impro~ement in the
third type of barrier pack. In its broadest aspect, the
present invention concerns a unitary flexible and expandable
barrier for use in a plural-zoned, valved pressure container
wherein the barrier has a shaped spatial form having
sufficient rigidity to maintain its shape prior to insertion
into and use in a plural~zoned, valved pressure conta;n~r.
The barrier comprises a flexible and ~p~n~hle wall portion
having an outer wall segment and an inner wall segment
connected by an angled fold, the free terminal end of the
outer wall segment forming a sealing means and the terminus of
the inner wall segment distal to the fold extending into a
central piston region that closes the barrier. In a preferred
form, the outer wall segment is steeply frustoconical in shape
and terminates at its free end in a sealing means, and the
inner wall segment is disposed in juxtaposed relation to the
inner surface of the outer wall and in steeply frustoconical
shape opposite to the frustoconical shape of the outer wall
segment so as to form a small acute angle between the outer
wall segment and the inner wall segment; the terminus of the
inner wall segment distal to the fold being closed by a
central piston region to thereby complete the unitary barrier
member. Further, the inner wall segment is sufficiently
flexible to permit the inner wall segment and said central
piston region to move in an axially downward direction under
the influence of product pressure when the barrier is top
sealed within a container, to assume a more or less phallic
~V096/02439 21 ~ 5 ~ v e~ 4
-- 6
configuration. Still further, the outer and inner wall
segments have sufficient flexibility and expandability to
extend outwardly under the influence of product pressure to
substanaially conform to the inner surface of the container.
When the outer wall segment is sufficiently thicker and more
rigid than the inner wall segment, the outer wall segment will
tend to continue to subst~nt;Ally conform to the inner surface
of the container, and the flexible inner wall segment will
invert within the outer wall segment under the influence of
propellant pressure to subs~ntiAlly return the barrier to
approximately its shape as initially disposed in the
container. Thereafter, the inner wall segment and central
pistor. area will stretch radially outwardly and upwardly to
substantially evacuate the product in the container. When the
outer wall 6egment is less thick and less rigid, the inner
wall segment and central piston will move axially upward under
the influence of propellant pressure, followed by both the
outer and inner wall segments crumpling tightly together and
moving upward. In this latter instance, at least ir. the case
of low ViscDsity products, product will be substantially
evacuated from the C~n~in~r.
By virtue of having sufficient rigidity to maintain its
shape prior to insertion into the container, as well as the
presence of the tapered outer wall segment, the barrier of the
present invention is very easily insertable into the top of
the container. By virtue of the tape.red outer and inner wall
segments, the barrier is nestable with like barriers for
conver.ience and cost savings in shipping. Further, the
wo g6l(~2439 21 9S~ O S P~ 4
- 7 -
nesting facilitates fast and simple machine feeding of stacked
barriers sequentially into the containers.
In a preferred form of the invention the outer wall
segment is thicker and more rigid than the inner wall segment;
the inner wall segment also is of slightly less length than
the outer wall segment; and the sealing means is a radially
extending flange which acts as a gasket between the top of the
sidewall of the container and the top closure of the
con~;n~r. The central piston region also may be thicker than
the inner wall segment.
A particularly advantageous material for barriers is
polyethylene ter~phth~l~te ~PET). Where permeation across the
barrier is a concern, the barrier of the present invention may
utilize a unitary multi-layer configuration. Such multi-layer
configurations, their materials of constructior. and their
manufacture, are well known to those skilled in the art.
Generally, in a three-layer ~ystem, the inner layer is a
material that prevents transport of propellant and product
therethrough and the outer layers are inert to the propellant
and product.
Brief Descri~tion of the Drawin~s
Eigure 1 is an elevational cross-sectional view of an
embodiment of the barrier of this invention.
Figure 2 is an elevational cross-sectional view of the
~ barrier of Figure 1 positioned within an empty aerosol
cnnt~;n~r with. the top opening of the container shown in
schematic and the aerosol valve not showr
W096/02439 ~ ~ r~-"~ ,. "~
21g~d~0~ --
Figure 3 is a schematic view of the barrier of this
invention within an aerosol ~nt~;n~r showing the barrier ir.
a pQsition after loading of the product into the container but
prior to introducing propellant to the container.
Figure 4 is a schematic view of the barrier of this
invention within an aerosol container after the product has
been partially evacuated from the container.
Figure 5 is a schematic view of the barrier of this
inventior. within an aerosol container after the product has
been further evacuated and the barrier has inverted to the
shape as initially present in the aerosol container, also
showing in dotted-line a full evacuation of product.
Figure 6 is a partial cross-sectional view of a
multilayered barrier of the present invention.
Figure 7 shows barriers of this invention in a nestirg
relation.
Figure 8 is a schematic diagram of the several steps used
in fabricating the barrier pack of this invention from a
plastic sheet.
Figure 9 is a schematic of the thermoforming equipment
used in forming the barrier pack of this invention.
~etailed ~escri~tion of the Invention
Referring now to the drawings, Figure 1 shows a unitar~
barrier generally designated at lQ, as it is initialiy formed,
said barrier having a wall 11 comprising a flexible and
~pRn~Rh1e outer wall segment 12 and a flexible and ~p~n~Rhle
inner wall segment 14 connected by a fold 15, the outer wall
WO9610~439 2 19~0~ P~ "~4
segment 12 terminating in a sealing flange 15. At the
terminus 18 of the inner wall segment 14, central piston
region 20 extends inwardly to close the barrier. It should be
noted that the outer wall segment 12 has a steeply
frusto-conical shape ~t~n~;nr~ from the sealing flange 16 to
the fold 15, and that the inner wall segment 14 has a steeply
frustoconical shape oppositely directed to the outer wall
segment 12 extending from the fold 15 to the central piston
region 20.
The outer wall segment 12, including the sealing flange
15, is sufficiently thick and rigid to impart a shaped spatial
form to the barrier and causes the barrier to be free-standing
and ready for insertion into the container.
It has been found that a barrier formed of PET with the
fOllowing ~i r;onC has performed satisfactorily as a barrier
in a pressurized container:
Sealing Flange Th;rkn~s - .007~
Outer Wall Segment Thirkn~,cc .007-,
adjacent the flange narrowing to .004
at the fold
Inner Wall Segment Thickness - .004
adjacent the fold narrowing to .002
adjacent the central piston region
Central Pi.ston Region - .002~ at the joinder
of the inner wall segment and the central
piston region and increasing to .004"
immediately within the aforesaid joinder and
thickening to .007" at the center area of the
piston
~ength of Outer Wall Segment - 3 1/8"
~ength of Inner Wall Segment - 2 19/32"
Container used with aforedescribed PFT
barrier was a 202 x 50~ straight sided
W096l02439 . ,~ 4
2 1 ~
- 10 -
can which is 2 1/8" in diameter and 5
9/16~ in length.
The barrier had a 1~ taper to each of the outer and inner wall
segments, 12 and 14, respectively, to form a fold 15 providing
an included angle of 2~ between the outer and inner wall
segments, 12 and 14. It is believed that a 3G taper to each
of the inner and outer wall segments will also function
satisfactorily. The central piston region for the
above-described barrier had a configuration as showr.in Figure
1, wherein the terminus 18 at the perimeter of the pist.on had
a depth of 0.188" and a radius of .063~1. The sealing flange
16 for the described barrier had a turning radius into outer
wall segment 12 of .078".
Figure 2 shows the barrier 10 inserted in a valved
pressure contAinPrl generally designated as 22, having inner
wall surface 23, and permanently ~oined to the c~nt~n~r 22
through the sealing flange 16 by an appropriate crimping of
the flange 16 between the joint formed by the upper end 25 of
the sidewall of the ront~in~r 22 and the perimeter of the
upper closure 27 of the container 22. Without intention to
limit the type of pressure container (aerosol) with which the
barrier pack of this invention may be usefully employed, it
has been found particularly useful when employed with an
aerosol container commonly referred to as a "necked-in"
container. A sealable port 28 is provided in the bottom
closure 26 for introduction of propellant. ~ manually
actuable valve (not shown) is positioned in a manr.er well-
wo 96,0243g 2 1 9 ~ 4 0 5 P~ "~
-- 11 --
known to those skilled in the art in the opening 29 of the
pressure container 22.
In Figure 2, the barrier lO divides the interior of the
cnnt~;nPr 22 into a plural zoned pressure container; the upper
zone 33 for receiving the product to be dispensed and the
lower zone 35 for receiving the propellant. Generally, the
container manufacturer will insert the barrier 10 into
container 22, and seal the barrier to the c~nt~;npr as
described above. A product filler will thereafter fill the
product and propellant into the respective chambers 33 and 35.
After sealing flange 16 between the top portion of the
container 22 and the upper sidewall of the container 22,
product is introduced into the product zone 33 to cause the
barrier 10 to fully expand downwardly within the r~nt~;nor 22
to substantially conform to the inner surface 23 of the
container 22, such as is shown in Figure 3. During the
filling of the product into the ~nt~;nPr it may be necessary
to provide a means for evacuating air in the propellant and/or
product zone. After introducing propellant into the
propellant zone 35, the c~ntA;nPr is ready to function to
discharge product through actuation of the aerosol valve
positioned in the ~nt~in~r opening 29.
Figure 2 shows a configuration for annexing the barrier
}Q to the container 22. Figure 2 shows the barrier pack 10
having a terminal flange 16 extending from the outer wall
segment 12. The flange 15 fits tightly between the flanges 25
and 27. The seam is formed by rolling the flanges 25, 27 and
16 toward the side wall 12 to form a rolled seam by techniques
W046/0~3~ P~~ 4
219540~ .
- 12 -
known to those skilled in the art. The thickness and length
of the sealing flange 16 is dictated by the requirements of
rolled seams, which may vary by type of ~n~in~r and rolling
equipment. The sealing flange 16 may be thicker than the
contiguous outer wall segment 12. Th.e sealing flange 16 may
function as a gasket in sealing the barrier to the base of the
container. If necessary, an adhesive may be provided ~.o the
components that are to be roll seamed.
Figure 3 shows the barrier in an initial position a short
period of time after loading the container with product. ~pon
continuous or intermittent actuation of the valve disposed in
the top opening of the pressurized container, product will be
evacuated from the container by lowering the pressure in the
product zone 33 and causing the greater pressure in the
propellant zone 35 to begin to invert the inner wall 14 of the
barrier 10 within the outer wall 12 and thereby force the
product through the discharge valve of the container. As
product is evacuated from the container 22, the inner wall
segment 14 and the central piston region 20 move. axially
toward the aerosol discharge valve as the barrier inverts, a
shown in Fig. 4.
If the outer wall segment 12 has a sufficient thickness
throughout from the terminal flange 16 to the fold 15, then
the outer wall segmer.t will continue to substantially conform
to the inner surface 23 of the container wal7 throughout the
product evacuation shown schematically in Figures 4 and 5.
The barrier then returns to approximately its initial shape as
shown in Fig. 5, followed by radial and axial stretching of
W09C102439 21 9 ~ ~ O ~ r~ l/U~ 4
- 13 -
inner wall segment 14 and central piston region 20 to the
dotted line configuration shown in Fig. 5 to obtain
substiantially complete product evacuation from the container.
To obtain this action, the thickness of outer wall segment 12
likely will need to be substantially greater than the .007"
thickness referenced above; without wishing to in any way be
limited, the thickness may be of the order of .020" to .025"
from flange 16 to fold 15, or sufficient to obtain the full
inversion of the inner wall segment within the outer wall
segment shown in Fig. 5. With this thicker outer wall segment
more viscous products may be fully evacuated from the
container without significant pocketing. The inner wall
segment will still remain thin and flexible.
If the outer wall segment 12 has a thickness of the order
of .007", the transition from Fig. 4 to nearly complete
product evacuation will result in both inner and outer wall
se~ tc 12 and 14 crumpling inwardly and tightly together,
and moving upwardly. In this instance, using water as a
simulated product, substantially complete product evacuation
was obtained from a test set-up without significar.t pocketing.
Where more viscous products are used, however, it is expected
that the thicker outer wall segment 12 will need to be
utilized to obtain the full product evacuatior. without
significant pocketing.
It has been observed that the frustoconical configuratior
of the inner wall segment 14 results in the inner wall segment
14 progressively inverting in an axial direction within the
outer wall segment 12, where outer wall segment 12 is
WO 96102439
- 2193~0~ ~
sufficiently thick, to cause the progressive advance of the
product. to the discharge valve and a minimization of the
capture or entrapment of product in pockets.
The tapering of the outer wall segment. facilitates the
invagination of the barrier of the present invention into the
pressurized container. The presence of the tapering of botn
the outer and inner wall segments, and at small angles, also
allows maximum nesting of the barriers for convenience and
cost savings in shipping the barriers from a manufacturins
site to the site of the container manufacturing operation. At
the container manufacturing site, the stacks of nested
barriers facilitate fast and easy feeding of the barriers
sequentially into the containers. Fach nested barrier may be
pulled from its stack into its intended container under the
influence of an initial vacuum in the container shell, each
barrier as it is inserted into its container shutting off the
vacuum; alternatively each nested barrier may be blown by air
from its stack into the intended C~nt~in~r. The next
cor.tainer shell is fed under the stack of nested barriers, and
the identical action continues for the next contairler and next
barrier. C~ntRin~rs continue to be sequentially fed under the
nested stacks of barriers, and the nesting provides for a high
speed and very simple feeding operation.
In order to overcome the problem of permeation of
propellant and~or product through the barrier found in prior
art dispensers, the flexible barrier in accordance with the
present invention is optionally made of a multilayered
materiai. Figure 6 shows a wall construction consistins of an
W096l02439 ~1 9 5~ P~l/uv ~ ~4
- 15 -
inner layer 102 designed to prevent transport of propellant
and product. Layer 102 is sandwiched between outer layers 104
and 106 that are inert to propellant or product in contact
with the outer layers. Adhesive layers 10& and 110 are
optionally provided, or alternatively the inner and outer
layers 102, 104 and 106 may be fused together by heat or other
means. In one embodiment, the inner layer 102 is a gas
barrier layer and the outer layers 104 and 106 are aqueous or
organic fluid barrier layers. The gas barrier layer may be
made of PET, ethylene vinyl alcohol, polyvinylalcohol,
polyvinylidene chloride, polyacrylonitrile, cellophane or
other similarly suitable materials. The outer layers may be
made of PET, polyethylene, (especially high density
polyethylene) polypropylene, polytetrafluoroethylene,
polybutane, surlyn ionomer, butyl rubber, polyvinylidene
chloride, polychlorotrifluoroethylene, Penton,
polyvinylfluoride or other similarly suitable materials.
Ethylene vinyl alcohol and polyvinyl alcohol are preferred gas
barrier materials and high density polyethylene is a preferred
aqueous or organic fluid barrier material.
Any propellants known in the art may be used with the
dispenser and flexible barrier of the present inver.tion. The
barrier of the present invention requires smaller amounts of
liquified propellants than required in non-barrier pack
aerosol systems and in certain barrier pack systems using
compressed gases, thus allowing the economic use of more
expensive propellants. The present system lends itself to a
WO 96,1U243~ ~ ~
~ ~,
2 1~S ~ 16 -
maximization of the amour.t of product to be dispensed from a
given cnnt~ i n~r .
The barrier pack of this invention as described at pagec
9 and lO hereof is presently manufactured utilizing a forming
process generally referred to as thermoforming. The
thermoforming technique for manufacturing plastic shapes from
a sheet of the plastic material is well-knowr. in a general
sense. Specific modifications of the general techniques are
used to tailor the thermoforming process to the forming of a
particular shape. The schematic diagram of Figure 8 shows
the several steps involved in the forming of the barrier packs
of this invention. In step 1, the plastic sheet materialr
PET, for e~ample, having a thickness of .025~, is passed
through a dry heat zone (oven) to bring the PET to a forming
temperature of 250~-330~F. It is desirable to have the PET at
285~-300~F., that is, to avoid the extremes of the 250~-330~F.
range. The PET material found suitable for forming the
barrier packs is biaxially oriented and suitable for deep draw
thermoforming.
2a The barrier pack of this invention is a deep drawn part
and thus is susceptible to '~webbing", i.e. the formation of a
fold of excess material at the mold base and the barrier side
wall. ~here "webbing" is a concern, carefui control of the
temperature of the plastic sheet material is critical.
Moreover, with temperature control and avoidance of a
temperature above the distortion temperature of the plastic
sheet material, a degree of plastic memory is retained by th*
W096l02439 2~ 0,~ J4
~ ~ .
- 17 -
plastic material, this memory aiding in the preclusion or
removal of the ~lwebbing" problem.
In step 2, the pre-heated PET sheet is moved to the
forming station ~thermoformer), whereat the PET sheet is
prestretched using a ~plug assist~ for the initial forming of
the inner wall segment and the pistor region of the barrier
pack and using a "ring" to partially form the outer wall
segment. Also see Eigure 9. The ~'ring~ assists in the
avoidance of l'webbing". The ~plug assist~' and "ring" are
mounted on the upper movable platen (top base plate) of the
thermoformer equipment, directly across from the lower movable
platen ~base plate) on which the mold is mounted. After
disposing the heated plastic sheet between the upper and lower
platens, the forming operation is ,-_ nred by moving the
platens toward each other to sandwich the heated sheet.
During the course of moving the platens until their ultimate
contacting against each other, the "plug assist" and ~ring~
draw the sheet into and around the interior cavity surface of
the mold to force the heated PET sheet to conform and contact
the mold at the fold joining the outer wall segment and the
inner wall segment and at the base of the "ring~. The ~ring~
in forcing the PET plastic sheet against the base plate of the
thermoforming equipment effects an annular seal around the
mold. After effecting the seal, vacuum is applied to the mold
to cause the PET plastic sheet to be drawn against the mold
surface and thereby complete the final shaping of the PET
plastic sheet.
WO 96/02439 . ~, I/u.,,~ 4
?.,~ 95 ~o5
- 18 -
The mold is water cooled, teflon coated aluminum, heat
conductive, and the ~plug assist" and "ring'~ are fine-grained
wood covered with felt to avoid scuffing and sticking of the
formed part.
After adequate cooling, the upper and lower platens are
separated and the formed sheet transported to the trimming
station ~step 3) whereat cutting dies trim the formed parts.
The formed parts are ejected to a stacker and the trimmed
residue at the sealing flange is ground for recycling and
reclaiming in the plastic sheet extrusion process.
It is believed that biaxial orientation of the plastic
during the extrusion of the plastic sheet to be thermoformed
decrease the permeation of the barrier material.
To manufacture a barrier with a thick outer wall segment
12 from the terminal flange 16 to the fold 15 as described at
page 12, line 13 through page 13, line 4, it may be necessary
to resort to "blow molding" processes utilizing controlled
parisons of the appropriate configuration. Such manufacturing
techniques are well within the skill of the art.
While the invention has been particularly shown and
described with respect to illustrative and preferred
embodiments thereof, it will be understood by those skilled in
the art that the foregoing and other changes in form and
details may be maàe therein without departing from the spirit
and scope of the invention which should be limited only by the
scope of the appended claims.
