U.S. patent application number 11/490817 was filed with the patent office on 2006-12-07 for product dispensing systems.
Invention is credited to Michael Ernest Garrett.
Application Number | 20060272537 11/490817 |
Document ID | / |
Family ID | 34812306 |
Filed Date | 2006-12-07 |
United States Patent
Application |
20060272537 |
Kind Code |
A1 |
Garrett; Michael Ernest |
December 7, 2006 |
Product dispensing systems
Abstract
In a dispensing system for dispensing a product form a canister,
which comprises a solid/gas arrangement in which the gas is
absorbed onto the solid under pressure and desorbed therefrom when
the pressure is released and in which the solid comprises activated
carbon and the gas comprises one or more of nitrogen, oxygen, (or
mixtures thereof including air) carbon dioxide, nitrous oxide and
argon, the container has valve means to allow the gas adsorbed onto
the carbon to be desorbed and effect product dispense.
Inventors: |
Garrett; Michael Ernest;
(Wiking, GB) |
Correspondence
Address: |
KLAUS J. BACH
4407 TWIN OAKS DRIVE
MURRYSVILLE
PA
15668
US
|
Family ID: |
34812306 |
Appl. No.: |
11/490817 |
Filed: |
July 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/GB05/00145 |
Jan 17, 2005 |
|
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11490817 |
Jul 21, 2006 |
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Current U.S.
Class: |
102/367 ;
222/183; 222/399; 222/95 |
Current CPC
Class: |
B65D 83/663
20130101 |
Class at
Publication: |
102/367 ;
222/399; 222/183; 222/095 |
International
Class: |
F42B 12/46 20060101
F42B012/46 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2004 |
GB |
0401512.9 |
Apr 8, 2004 |
GB |
0407991.9 |
Aug 27, 2004 |
GB |
0419135.9 |
Aug 27, 2004 |
GB |
0419137.9 |
Dec 2, 2004 |
GB |
0426490.9 |
Claims
1. A dispensing system for dispensing a product from a canister,
comprising a solid/gas arrangement in which the gas is adsorbed
onto the solid under pressure and desorbed therefrom when the
pressure is released and in which the solid comprises activated
carbon and the gas comprises at least one of nitrogen, oxygen (or
mixtures thereof including air), carbon dioxide, nitrous oxide and
argon, the container having valve means to allow the gas adsorbed
onto the carbon to be desorbed for generating a pressure in the
container and effect product dispense.
2. A dispensing system according to claim 1, wherein the gas
comprises carbon dioxide.
3. A dispensing system according to claim 1, wherein the dispensing
system is incorporated into a canister in which the product to be
dispensed is held under gas pressure.
4. A dispensing system according to claim 3, wherein the container
includes individual compartments and the product and the solid/gas
arrangement of the dispensing system are present in the different
compartments in the canister.
5. A dispensing system according to claim 4, wherein the different
compartments are separated by a fixed partition.
6. A dispensing system according to claim 5, wherein the different
compartments are solid/gas and product compartments divided by a
partition and a one-way valve is disposed in the partition for
controlling the floe of gas from the solid/gas compartment into the
product compartment.
7. A dispensing system according to claim 4, wherein a one-way
valve is arranged in the carbon container to prevent back flow of
the gas from the solid/gas compartment in order to allow the
introduction of carbon dioxide into the solid/gas compartment and
retain it therein prior to use of and during use of the system.
8. A dispensing system according to any one of claim 4, wherein a
single valve is provided in the partition adapted to operate
separately as a pressure sensitive valve in either direction
depending on the requirements of the system.
9. A dispensing system according to claim 1, wherein the product
and the solid/gas arrangement of the dispensing system of the
invention are arranged in different compartments in the canister
which are separated by a displaceable partition impermeable to the
gas.
10. A dispensing system according to claim 9, wherein the
displaceable partition is in the form of a bag for holding the
product.
11. A dispensing system according to claim 9, wherein the
displaceable partition is in the form of a piston slideable
disposed within the canister.
12. A dispensing system according to claim 1, wherein the product
is exposed to gas pressure only upon its dispense.
13. A dispensing system according to claim 12, wherein the desorbed
gas pressure acts directly on a product to effect product dispense
by urging the product through a dip tube extending into the product
in the canister.
14. A dispensing system according to claim 12, wherein the desorbed
gas pressure acts indirectly on the product to effect product
dispense by impingement onto a piston slideably mounted in a
canister body or part thereof.
15. A dispensing system according to claim 12, in which the
desorbed gas is conducted through a mixing structure wherein by
fluid dynamic (fluidic) action a vacuum is formed into which the
product is drawn.
16. A dispensing system according to claim 15 in which the desorbed
gas is caused to flow through a venturi to which the product
container can be linked to effect product dispense.
17. A dispensing system according to claim 12, wherein valve means
are provided to release the pressure applied directly or indirectly
to the product to effect its dispense when the canister is not
being used.
18. A dispensing system according to claim 1, wherein the activated
carbon is held in a carbon chamber which is proximate to a
dispensing block.
19. A dispensing system according to claim 18, wherein the
dispensing block and the carbon container are joined by being made
as an integrally formed unit.
20. A dispensing system according to claim 19, in which the carbon
chamber is situated beneath the dispensing block in a normal
upright orientation of the canister.
21. A dispensing system according to claim 1, wherein a pressure
regulator is provided to regulate the gas pressure released from
the adsorbent of the dispense system of the invention to a
predetermined pressure level.
22. A dispensing system according to claim 21, wherein the carbon
dioxide is injected into the carbon container in liquid form.
23. A dispensing system according to claim 22, wherein a double
valve arrangement is employed for measuring exact quantities of
liquid carbon dioxide present between two valves positioned in a
delivery tube of constant cross-section.
24. A dispensing system according to claim 1, wherein a separate
bleed of gas is directed into the dispensing valve or block and,
therein, to mix with the product being expelled therefrom in order
to effect a greater dispersion of the dispensed product.
25. A dispensing system according to claim 1, wherein the activated
carbon is present in the form of pellets or torroids.
26. A dispensing system according to claim 1, wherein the activated
carbon is kept in contact with a blanketing atmosphere prior to its
placement in the canister.
27. A dispensing system according to claim 26, wherein the
blanketing atmosphere comprises the adsorbed gas itself.
28. A dispensing system according to claim 1, wherein the product
is pre-treated with adsorbed gas prior to, or during, its
introduction into the canister.
Description
[0001] This is a Continuation-In-Part Application of International
Application PCT/GB2005/000145 filed Jan. 17, 2005 and claiming the
priority of GB applications 0401512.9, 0407991.9, 0419135.9,
0419137.9 and 0426490.9 filed Jan. 23, 2004, Apr. 8, 2004, Aug. 27,
2004, Aug. 27, 2004 and respectively, Dec. 2, 2004.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to systems for dispensing
substances from containers and, more particularly, to such systems
employing a very simple but effective two phase solid/gas
adsorption/desorption mode of operation.
[0003] A large number of products are on the general market
packaged in canisters--some of which cause the product to be
dispensed therefrom in the form of small or atomized particles and
are therefore commonly referred to as `aerosols`--which can be
dispensed from the canister by means of a pressurized gas (or
vapor) which is generated in situ in the canister and acts as a
dispensing or propellant gas. Such products include ones for
personal care including hair sprays, shaving creams, deodorants and
the like and ones for household use including cleaning substances,
room fragrances, insect repellents and the like, and many more.
[0004] In some cases, such products are admixed with the
pressurized gas in the canister and the operation of a (typically)
push-down operating valve causes both the product and the gas to be
dispensed from the pack by means of the gas pressure via a `dip
tube` extending into the product and linked to a nozzle which is
commonly associated with the release valve, all of which are
commonly contained in a dispense assembly or dispense block.
[0005] In other cases, the product and pressurized gas are
separated from each other within the canister. Typically, some form
of divider or membrane is present in the canister, for example, one
in the form of a bag containing the product which is sealingly
attached to the canister internal wall in the vicinity of the
release valve; the gas is present between the divider and the
internal walls of the pack, i.e. surrounding the bag and the gas
pressure in turn exerts pressure on the product in the bag.
[0006] Alternatively, the divider may be a piston which slides
within the canister with the product on one side and a gas on the
other side and which acts to drive the product from the canister by
the action of gas pressure.
[0007] Whichever type of pressure pack is adopted will depend on
the nature of the product and the use to which it is to be put and
on the nature and properties of the propellant gas, in particular
whether the propellant gas might react with the product or whether,
for example, it might be flammable or odorize the product.
[0008] The use of chlorofluorocarbons (CFCs) previously became very
popular as propellant gases for such product dispense canisters in
that they can be readily condensed and vaporized in a reversible
manner responsive to the surrounding pressure. This was followed by
the use of hydrofluorocarbons (HFCs) and also
hydrochloroflurocarbons (HCFCs) which were regarded as being
somewhat more environmentally friendly.
[0009] However, more recently, such propellant gases have in
general been phased out owing to their acknowledged environmentally
harmful properties, in particular ozone depletion of the upper
atmosphere.
[0010] Alternative propellant gases which have been commonly used
are certain hydrocarbon gases including liquid petroleum gases
(LPGs) such as propane and butane. Such gases, however, are by
their nature extremely flammable, are environmentally harmful in
some respects and in addition can introduce an odour into the
product being dispensed.
[0011] It is known that numerous attempts have been made to replace
LPG propellant gases with gases such as air, nitrogen, carbon
dioxide and the like. These attempts have largely been effected
simply by utilizing a pressurized gas within the canister; in
practice, the canister valve is depressed to propel the product
from the canister in the general manner described above.
[0012] However such attempts have been largely unsuccessful due to
the large pressure changes in the canister during use, commonly
leading to reduced dispense characteristics at low pressures and a
loss of pressure before full product dispense which results in a
slow dispense of the last product from the canister.
[0013] In addition, it is known that there has been considerable
effort to develop further alternative propellant systems for such
product dispense. For example, there is disclosed in European
Patent Application No. 385 773 the use of two-phase gas/solid or
gas/liquid or three phase gas/liquid/solid propellant systems in
which the solid is a polymer having molecular microvoids occupied
by the gas or gas/liquid under pressure and the gas is released
therefrom when the pressure of the system is reduced.
[0014] There is additionally disclosed in a further European Patent
Application No. 502 678 the use of a three phase gas/liquid/solid
propellant system in which the solid is a material such as a foam
or a fibrous mass having open voids occupied by the gas/liquid
under pressure and the gas is released therefrom when the pressure
of the system is reduced.
[0015] It is known that efforts to develop such prior systems were
based primarily on the preferred embodiments described in these
European applications, namely the use of a gas/liquid/solid system
in which carbon dioxide as the gas was dissolved in acetone as the
liquid which itself occupied voids in a solid.
[0016] The use of acetone as the liquid in such a system would
generally mean that it was useful only in canisters employing a
membrane, for example a bag containing the product, in order to
separate the propellant system from the product to be dispensed.
However, acetone is an aggressive chemical and it is also known
that it was found that the use of acetone in such systems tended to
cause problems associated with chemical attack of the membrane
material and leakage of the acetone through and around the membrane
and resulting failure of the membrane.
[0017] A further prior attempt to produce a product dispense system
utilizing gas pressure is disclosed in UK Patent Specification No.
1 542 322 in which a propellant gas, including propane/butane,
certain CFCs and carbon dioxide, is adsorbed onto a solid with the
dispense gas pressure being produced in situ during use of the
system by means of bringing the solid into contact with a
propellant displacing agent--preferably water--in order to release
the adsorbed gas. As such, the system as a whole is necessarily
very complex due in particular to the need to employ the propellant
displacing agent during use and provide means to bring it into
contact with the solid.
[0018] It is therefore the object of the present invention to
provide an improved aerosol propellant system that overcomes the
problems associated with currently available systems.
SUMMARY OF THE INVENTION
[0019] In a dispensing system for dispensing a product form a
canister, which comprises a solid/gas arrangement in which the gas
is absorbed onto the solid under pressure and desorbed therefrom
when the pressure is released and in which the solid comprises
activated carbon and the gas comprises one or more of nitrogen,
oxygen, (or mixtures thereof including air) carbon dioxide, nitrous
oxide and argon, the container has valve means to allow the gas
adsorbed onto the carbon to be desorbed and effect product
dispense.
[0020] It has now been found that the use of a new system not
involving polymeric materials and not involving troublesome liquids
or displacing agents and being more suitable for commercially
viable assembly into the aerosol canister can provide an efficient
sorption/desorption propellant system for product dispense.
[0021] In accordance with the invention, there is provided a
dispensing system for dispensing a product from a canister, which
comprises a solid/gas arrangement in which the gas is adsorbed onto
the solid under pressure and desorbed therefrom when the pressure
is released and in which the solid comprises activated carbon and
the gas comprises one or more of nitrogen, oxygen (or mixtures
thereof, including air), carbon dioxide, nitrous oxide and argon,
the container having valve means to allow the gas adsorbed onto the
carbonto be desorbed and effect product dispense.
[0022] The gas is preferably carbon dioxide in view of its
generally superior adsorption characteristics in relationto
activated carbon as an adsorbent.
[0023] The term `adsorbed gas` used herein refers to the gas used
in the invention.
[0024] It has been surprisingly found that such a system, despite
its simplicity, can provide the basis for an efficient, safe,
reliable and reproducible system for product dispense.
[0025] It has been found in particular that the new dispense system
can provide--by means of careful selection of the type of activated
carbon employed, the amount of carbon, the initial pressure and
therefore the amount of gas adsorbed on the carbon--a low pressure
change during intermittent use between an initial product dispense
and full product dispense from a canister.
[0026] The pressure change afforded by the invention between a
`full` and `empty` canister is such that the canister in which it
is positioned can maintain an effective discharge of the product
with an effective and acceptable controlled spray pattern in terms
in particular of its being uniform and/or homogeneous with a
predetermined particle size and distribution.
[0027] Systems of the invention have been shown to be particularly
suited to the dispensing of products from small, hand-held
`aerosol` canisters, for example ones having a 200 or 300 ml
capacity. The term `aerosol` when used herein includes any
hand-held dispensing devices for the delivery of product whether or
not the product is actually atomized or whether or not it incurs
any other form of product break-up.
[0028] In the implementation of the invention, and a first
embodiment thereof, the dispensing system is preferably
incorporated into a canister in which a product to be dispensed is
held under gas pressure. In such an embodiment, carbon dioxide
desorbed from the carbon adsorbent pressurizes the canister and
maintains the pressure therein generally and during actuation of
the canister dispensing valve in particular.
[0029] Preferably, the product and the solid/gas arrangement are
present in separate compartments in the canister. This is primarily
to keep the product and the solid apart from each other in order to
hold the solid in a predetermined part of the canister and/or to
ensure in particular that the product, which may for example be in
aqueous or other type of solution, does not contaminate the solid
and thereby detract from its efficiency of adsorption.
[0030] In some instances, the compartments may be separated by
means of a wholly or substantially impermeable membrane. This
membrane may take the form of a flexible bag which is sealingly
attached either to the interior wall of the canister or to the
canister operating valve or dispense block and which in use holds
the product to be dispensed. The solid/gas arrangement is generally
positioned within the canister outside the bag such that pressure
is exerted on the exterior of the bag when pressure therein is
released on actuation of the valve and a product is dispensed via
the valve through a nozzle. An elastic material may be employed to
form the bag. Furthermore, the membrane, whether of elastic or
non-elastic material may be used and may be sealingly attached to
any relevant part of the canister interior.
[0031] The substantially impermeable membrane may alternatively
take the form of a piston slidably mounted in the canister interior
with the gas/solid arrangement on one side of the piston and the
product to be dispensed on the other side such that actuation of a
dispense valve causes pressure from gas desorbed from the solid to
move the piston and urge the product to be dispensed from the
canister via the valve.
[0032] In other instances, the compartments may be separated by
means of a fixed partition. Such a fixed partition may usefully be
positioned in any useful part of the canister and preferably
include the base thereof, to form the solid/gas arrangement
compartment therein. It can, for example, be a concave-shaped disc
in a `flat` canister base or one of greater concavity than the
(usually) concaveshaped canister base (as viewed from the exterior
of the canister). It may advantageously be crimped to the canister
between the canister wall(s) and its base to form an annular
compartment between the disc and the base.
[0033] The solid compartment may also be in the form of a container
or `widget`that may be fixed to the canister (or part thereof) or
allowed to be free within the canister interior.
[0034] In addition, the carbon container may be associated with the
canister dip tube, for example by being mounted around the dip tube
for ease of assembly of the canister generally and the positioning
of the container therein and, separately to allow for a ready
filling of the container with adsorbed gas via the dip tube and via
a one-way valve therebetween.
[0035] Generally, the product and the solid/gas arrangement of the
dispensing system of the invention are present in individual
compartments in the canister, which are separated by a partition
which may be fixed or displaceable. This keeps the product and the
solid apart from each other in order to hold the solid in a
predetermined part of the canister and/or to ensure in particular
that the product, which may for example be in aqueous or other type
of solution, does not contaminate the solid and thereby detract
from its efficiency of adsorption.
[0036] With a fixed partition, for example the substantially rigid
wall of the carbon container, it is generally required that the gas
from the solid/gas compartment can flow into the product
compartment, but not vice versa, and this can readily be effected
by having a one-way valve in the partition.
[0037] Equally, there is a general need to provide means to allow
the introduction of carbon dioxide into the solid/gas compartment
prior to use of and during use of the system; this can also be
effected by a one-way valve to prevent back flow of the gas from
the solid/gas compartment.
[0038] Each one-way valve should be designed such that it operates
only under a certain applied pressure, for example a small fraction
of 1 bar; otherwise the valve does not open.
[0039] With certain valve designs, it is possible for a single
valve to operate separately as a pressure sensitive valve in either
direction depending on the requirements of the system.
[0040] In such embodiments, the container for the carbon should
have one-way valve means in order to allow the carbon dioxide to be
desorbed from the solid and pass into the product compartment when
the pressure in the canister falls, ie on operation of the canister
dispensing valve, and thereby maintain canister pressures at
predetermined levels for further use of the aerosol.
[0041] In all cases, the one-way valve means may be made from any
material and be of any suitable form including ones incorporated
integrally into the body of the carbon container. One form which is
particularly useful may comprise an upstanding valve body
terminating in a parallel, double plate arrangement--preferably
formed integrally with the wall of a product bag or fixed
partition--such that the plates act as a closed valve in their
usual position but which can move under their inherent resilience
to an open position by virtue of gas pressure impinging thereon in
a predetermined (single) direction, ie from the interior of the
carbon container; such a valve is sometimes referred to as a
`sphincter` valve.
[0042] The one-way valve advantageously is formed integrally with
the partition and is preferably made from a plastic material, for
example PET or silicone rubber.
[0043] With a displaceable partition, this will generally be
impermeable to the gas and may take the form, for example, of a bag
for holding the product or a piston slideable within the canister
with the desorbed gas from the carbon deforming the bag or moving
the piston within the canister under the increased gas pressure
applied thereon during actuation of the dispensing valve.
[0044] In different embodiments of the invention, the dispensing
system may be implemented with a product not held before its
dispense under gas pressure. In such embodiments, the desorbed gas
is not used to effect product dispense until it is required in use.
These embodiments may be put into effect by restraining the gas
pressure in the solid/gas container and effecting its release
therefrom via valve means only when required during product
dispense.
[0045] In these different embodiments of the invention, the
desorbed gas may be used to effect product dispense by: [0046] i)
causing the desorbed gas pressure to act directly on a product to
effect product dispense, for example by urging the product through
a dip tube inserted into the product in the canister, or [0047] ii)
causing the desorbed gas pressure to act indirectly on the product
to effect product dispense, for example by its acting on a piston
slideably supported in a canister body or part thereof, or [0048]
iii) causing the desorbed gas to effect product dispense by fluid
dynamic (fluidic) action through the formation of a vacuum into
which a product is drawn, sucked or otherwise urged, for example by
causing desorbed gas to flow through a venturi in which the gas
flow is increased and the pressure is decreased in the `throat`0
thereof, ie a partial vacuum is formed, and to which the product
container can be linked to effect product dispense.
[0049] In these separate embodiments of the invention, it may be
advantageous --especially in regard to paragraphs i) and ii)
above--to provide valve means to release the pressure applied
directly or indirectly to the product to effect its dispense when
the canister is being used.
[0050] Use of the separate embodiments with an unpressurized
canister is particularly useful in the case of a product in which
the propellant gas can dissolve.
[0051] In all embodiments, the carbon is advantageously held in a
container which is preferably proximate to the dispensing block,
for example by being attached thereto or may be less firmly linked,
for example via a tube through which the carbon dioxide can be
introduced into the container.
[0052] In such preferred embodiments, the dispensing block itself
advantageously incorporates a canister dispensing valve and
passageways linking the interior of the canister with the exterior
thereof via the valve. As such, the dispensing block, together with
the carbon container, can readily and effectively be sealingly
inserted into an aperture in the canister during canister
assembly.
[0053] In particular, the linkage of the container to the
dispensing block generally allows firstly for a ready operation of
the pressure pack and secondly allows for a simple mode of
manufacture and assembly of the aerosol canister by allowing for
the dispensing block--incorporating the canister dispensing valve,
necessary passageways linking the interior of the canister with the
exterior thereof, and also the carbon container linked thereto--to
be inserted into an aperture in the canister, ideally the top of
the canister, advantageously in a single assembly step.
[0054] The invention therefore allows canisters of standard designs
to be employed without modificationto the body thereof in order to
suit implementation of the invention generally and to include
canisters made of either steel or aluminum or other material.
[0055] In preferred embodiments, the dispensing block and the
carbon container are advantageously joined, for example by being
made as an integrally formed unit, for example with the carbon
container being situated beneath the dispensing block in a normal
upright orientation of the canister. It is also advantageous for a
dip tube to depend from the dispensing block, preferably being
positioned centrally (axially) in the carbon container and, during
use of the propellant system, extending into the body of the
canister which includes the product to be dispensed.
[0056] The container for the carbon can be, for example, made of a
flexible plastic/polymer material in the form of a bag or
alternatively be cylindrical in shape and advantageously made from
a more rigid material, again preferably from a plastic/polymer
material. The container is preferably cylindrical in shape.
[0057] In general, it is preferred for the carbonto be placed in
the container prior to the final assembly of the canister, ie prior
to insertion of the dispensing block and into the product itself to
which the container is linked into the canister aperture as
described above.
[0058] The product to be dispensed by the system of the invention
is commonly inserted into the canister via a dip tube depending
from the dispensing block and through which, during use of the
aerosol, the product is dispensed via the dispensing valve in the
reverse direction. The solid/gas container is advantageously linked
to the dispensing block, for example by being positioned co-axially
about the dip tube and as such can be regarded as an integral part
of the dispensing block. In such cases, the block as a whole can
therefore readily be placed in a canister aperture simultaneously
during assembly of the canister.
[0059] Means must also be provided for the introduction of the gas
under pressure into the carbon container in order to cause it to be
adsorbed onto the carbon and subsequently desorbed therefrom on
operation of the dispensing valve. This can be effected, for
example, by providing a suitable route via the dispensing block
into the container interior and including (as described above) a
one-way valve to prevent back flow of the gas.
[0060] Overall, therefore, and in all embodiments of the invention,
the product dispensing system provides a simple and effective way
of utilizing gas desorbed from the adsorbent per se in order to
provide a sufficient gas volume to produce an initial gas pressure
and thereafter to maintain gas volumes, and necessary gas
pressures, to enable a complete product dispense to be
effected.
[0061] In all embodiments of the invention, a pressure regulator
may be used to regulate the gas pressure released from the
adsorbent of the dispense system of the invention to a
predetermined pressure level or within a predetermined range of
pressure. For example, a 10 bar(a) pressure provided by desorbed
gas may be regulated to produce propellant gas at 3 bar(a).
[0062] With regard to the gas, it should be introduced into the
dispensing system under pressure and which will be adsorbed onto
the carbon such that its molecules are much more closely packed
together than in the usual gaseous form at the same temperature and
pressure.
[0063] This means that, when the gas is introduced under pressure
into a "gas space" surrounding the carbon, considerably more gas
will be adsorbed onto the carbon. Consequently, as the system is
activated, typically by actuating the pressure release valve, there
will in practice be only a relative and surprisingly small pressure
reduction within the system which, in use of the system, therefore
allows for the effective dispensing of all of the product.
[0064] In preferred embodiments utilizing carbon dioxide gas, it is
injected initially under pressure in liquid form, for example down
a dip tube depending from or integrally formed with the valve
block.
[0065] Adding the carbon dioxide in this way will generally produce
a mixture of carbon dioxide snow and cold carbon dioxide gas.
[0066] Using carbon dioxide in the form of a liquid or snow can in
practice at least partially thermally balance the heat of
adsorption of the carbon dioxide onto the carbon and maintain
temperatures close to ambient.
[0067] A double valve arrangement may be employed for measuring
exact quantities of liquid carbon dioxide present between two
valves positioned in a delivery tube of constant cross-section so
as to define the required volume of gas needed for each canister as
they pass along a conveyor assembly line. This is preferably
effected by closing the upstream valve once the required volume of
carbon dioxide is present between the valves and allowing the
volume to `vaporize`, and to urge the stream of snow/gas into the
canister.
[0068] The gas may also be charged into the container in the form
of solid carbon dioxide which is easy to handle and affords the
benefits described above for liquid carbon dioxide.
[0069] In general, it is beneficial to charge the gas into the
container by means other than a `bung hole` in the base of the
canister as the presence of a bung hole may lead to gas leakage
during storage/use of the canister.
[0070] Activated carbons are well known per se and have the
advantage that they are relatively inexpensive; they are
non-polymeric substances. In general, activated carbons are
manufactured from a variety of carbonaceous materials including (1)
animal material (blood, flesh, bones, etc), (2) plant materials
such as wood, coconut shell, corn cobs, kelp, coffee beans, rice
hulls and the like and (3) peat, coal, tars, petroleum residues and
carbon black.
[0071] Activation of the raw carbonaceous materials can be effected
in a variety of known ways including calcining at high temperature
(eg 500.degree. C. -700.degree. C.) in the absence of air/oxygen
followed by activation with steam, carbon dioxide, potassium
chloride or flue gas at, say, 850.degree. C. to 900.degree. C.,
followed by cooling and packaging.
[0072] Selected activated carbons are suitable for use in the
systems of the invention, for example ones having a density of from
0.2 g/cm.sup.3 to 0.55 g/cm.sup.3, preferably 0.35 g/cm.sup.3 to
0.55 g/cm.sup.3.
[0073] The quantity of carbon required in implementing the
invention will vary depending on parameters including the gas
employed, the initial and final pressures during the dispense of
product, the nature of the product and its physical characteristics
and the desired properties of the dispensed product. As such, the
carbon may advantageously occupy from 5 to 95% of the canister
interior volume.
[0074] In the case of a standard size (300 ml) canister, it is
preferred for many product types to have a carbon content of from 5
to 30% of carbon (by volume) which generally equates, for selected
carbons, to the presence of 10 to 60 ml of carbon, more preferably
30 to 50 ml of carbon, for example 40 ml of carbon.
[0075] With other product types, especially those of relatively
high concentration of active ingredient(s), the carbon content may
usefully be from 30 to 95%, preferably from 60 to 90%.
[0076] In the case of the higher concentration products in
particular, but also generally, the product dispensed from the
nozzle of a canister incorporating a system of the invention may
advantageously be improved by causing a separate bleed of gas to be
directed into the dispensing valve or block and therein to mix with
the product being expelled therefrom in order to effect a greater
dispersion of the dispensed product.
[0077] Such improvements are especially useful with more
concentrated and/or more viscous products which might otherwise be
difficult to disperse adequately for obtaining an effective spray
pattern or whatever.
[0078] In preferred embodiments of the invention, the activated
carbon is present in the form of one or more pellets or torroids,
ie in a much larger size than the granules in which it is normally
supplied, for example of a size of at least 0.5 cm in length or
greater. Such pellets or torroids may be fabricated by sintering or
other binding processes and preferably will allow for a much larger
surface area for the carbon dioxide and therefore a commensurately
larger and more effective gas release on a reduced pressure.
[0079] The pellets or torroids can advantageously be manufactured
as sticks or tubes and/or with surface ribs or grooves or with
apertures therethrough; all such forms can be capable of aiding
adsorption/desorption of the gas.
[0080] In general, specific ways of treating and/or handling the
carbon are important aspects of the invention and may be essential
for the implementation of dispensing systems of the invention.
[0081] In particular, it has been found that there may be a
propensity for the required properties of the carbonto degrade
after the carbon activation process. Such degradation may include
adsorption sites on the carbon being blocked by a gas or gases
present in the atmosphere present around the carbon and which
cannot subsequently be displaced by the gas that is to be adsorbed
as the working gas in the dispensing systems of the invention.
Although the blocking process may be reversible in certain cases,
displacement by the preferred gas may not be effected completely
and therefore would detract from the subsequent adsorption of the
gas. In some instances, desorption of the initially held gas may be
aided by high temperature and/or vacuum.
[0082] In accordance with preferred aspects of the invention,
therefore, the activated carbon is held, advantageously from the
time of its production, under a blanketing atmosphere; this
atmosphere may comprise the adsorbed gas itself, or a gas or gases
(including mixtures with the adsorbed gas) that do not prevent the
adsorbed gas subsequently occupying the carbon adsorption sites, in
particular by virtue of being held at the adsorption sites on the
carbon less strongly than the adsorbed gas.
[0083] Certain gases, including water vapor, are more strongly held
at the carbon adsorption sites than the adsorbed gas and carbon
dioxide in particular and therefore should be rigorously excluded
from the atmosphere around the carbon; subsequent attempts to
dislodge the strongly held gases will not be successful.
[0084] Although some gases are less strongly held at the adsorption
sites than carbon dioxide and other adsorbed gases, they may still
interfere with the subsequent adsorption efficiency characteristics
of the adsorbed gas and should be avoided as blanketing gases.
[0085] In the case of carbon dioxide as the adsorbed gas, the
blanketing atmosphere preferably includes or comprises carbon
dioxide itself. This can be especially advantageous in the
implementation of the invention in dispensing systems when the
carbon dioxide is preferably adsorbed onto the carbon at elevated
temperatures. Other suitable gases include helium and hydrogen
which are generally capable of being displaced from the adsorption
sites by carbon dioxide. The potential use of other blanketing
gases can be established by a skilled adsorption scientist on a
theoretical or practical basis.
[0086] Adsorption is an exothermic process in which considerable
amounts of heat may be generated. The adoption of these preferred
embodiments with a blanketing atmosphere that includes carbon
dioxide itself is beneficial in that it allows an initial level of
adsorption of carbon dioxide to occur--together with a dissipation
of the generated heat--prior to the use of the carbon in dispensing
systems of the invention. This can lead to significant advantages
from the resultant lower amounts of heat generated when the
remaining carbon dioxide is adsorbed under pressure in subsequent
high speed production of canisters incorporating the dispensing
systems of the invention.
[0087] With all adsorbed gases, the blanketing of the carbon is
preferably effected from the time of cooling and is preferably
maintained continuously up to the time of (final) assembly of the
canisters in which the dispensing systems are employed. To achieve
this, the use of containers for holding the blanketed carbon is
required in order to isolate the carbon from undesirable gases.
[0088] In any event, the carbon granules or pellets or torroids may
advantageously be pre-saturated with carbon dioxide (or other
adsorbed gas) prior to use in order to improve the adsorption
parameters. The granules/pellets/torroids may be advantageously
cooled in such pre-saturation processes by use of cooled carbon
dioxide, for example solid carbon dioxide or snow being in contact
with the granules or pellets.
[0089] In preferred embodiments and as stated above, the carbon
granules/pellets/torroids are usefully kept in contact with a
source of carbon dioxide or other adsorbed gas, especially cold
gas, liquid or snow, prior to placement in a canister and this may
provide sufficient adsorbed gas for use in the system without the
need to add further amounts of gas.
[0090] In the case of certain products, it has been found that it
may be useful for optimum dispense characteristics to pre-treat the
product with adsorbed gas prior to, or during, its introduction
into the canister. This can be especially useful in the case of
highly soluble gases such as carbon dioxide, ie `pre-carbonation`.
Such a process is more useful in the case of product to be admixed
with the adsorbed gas in the canister; it may, however, also apply
to product present in the canister separated from the adsorbed gas
by a moveable partition including a bag whether or not the
partition allows for a certain leakage of gas therethrough.
[0091] Working canisters incorporating the product dispense systems
of the invention have been made to good effect in terms in
particular of initial and final gas pressures during full product
dispense as exemplified below with carbon dioxide adsorbed gas in
particular: TABLE-US-00001 Canister volume 300 ml Carbon volume 50
ml `Free` canister volume 250 ml Liquid product volume 225 ml
Initial gas pressure 6 bara Final gas pressure 4 bara (following
full product dispense)
[0092] Tests on a canister containing a larger carbonto product
volume ratio resulted in a proportionately lower change between
initial and final pressures.
[0093] All tests were conducted using activated carbon samples
treated and handled with a carbon dioxide blanketing atmosphere
from the time of cooling during production of the carbon.
[0094] Tests with other adsorbed gases produced similar results
depending on the adsorption characteristics of the individual
gases.
[0095] The invention will be described below in greater detail with
reference, by way of example only, to the accompanying
drawings.
Brief Description of the Drawings
[0096] FIG. 1 shows a schematic vertical section through a canister
incorporating a dispensing system of the invention;
[0097] FIG. 2 shows a sectional view through the canister of FIG. 1
along the line II-II; and
[0098] FIG. 3 shows a schematic vertical section through a canister
of different design to that of FIG. 1 incorporating a dispensing
system of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0099] With reference to the drawings and to FIG. 1 in particular,
there is shown a canister 1 incorporating a pressure pack
dispensing system of the invention. The canister 1 comprises a
cylindrical main body portion 2, a circular base portion 3 of
concave shape (external view) and a circular top portion 4 of
convex shape (external view), all made of aluminum alloy
material.
[0100] The base portion 3 is sealingly crimped around its periphery
to the lower edge of the main body portion 2 in a manner known per
se for aerosol canister in particular.
[0101] Sandwiched and sealingly held within the crimped structure
between the main body portion 2 and the base portion 3 is a
circular partition 5 made of plastic and having a greater concavity
shape than the base portion 3.
[0102] The base portion 3 has a small circular "bung" 6 at its
centre made of rubber (or other elastomer) and the partition 5 has
an upstanding one-way valve 7 allowing for the flow of fluid from a
compartment 8 formed between the base portion 3 and the partition 5
and into the upper compartment containing the substance to be
dispensed but not vice-versa.
[0103] The one-way valve 7 comprise two upstanding plates 9, 10
(see FIG. 2) which are formed integrally with the partition 5 and
which, by virtue of the relative positioning of the plates 9, 10
and the nature of the plastic material from which they are made,
are biased to lie adjacent each other in the vicinity of their ends
furthest from the partition 5.
[0104] As such, the one-way valve 7 will open by parting the plates
9, 10 when there is, in use, an excess pressure in the compartment
8 over that in the interior of the remainder of the canister 1.
[0105] The plates 9, 10 will not part and the valve 7 will
therefore not operate in the opposite direction as any excess
pressure in the canister 1 will not cause such parting by virtue of
the shape of the adjacent ends of the plates.
[0106] The top portion 4 is sealingly crimped around its periphery
to the upper edge of the main body portion 2 again in a manner
known per se for aerosol canisters in particular.
[0107] Positioned centrally of the top portion 4 in an aperture
thereof is an operating valve system 11 comprising a valve seat 12
against which a ball valve member 13 is in its "closed" position
held but which can be unseated in its "open " position by
depression of an operating button 14 against the action of a spring
15. Release of the button 14 causes re-seating of the valve member
13 by means of the spring 15.
[0108] A tube 16 depends downwardly from the valve system 11 and a
discharge line for the substance to be dispensed is formed from the
lower end of the tube 16, through the tube 16 itself and via the
valve mechanism to a discharge port 17 in the operating button
14.
[0109] In the manufacture of the canister 1, activated carbon 18 is
included in the compartment 8 between the base portion 3 and the
partition 5 and the substance to be dispensed is charged into the
canister 1 above the partition 5 via the aperture in the top
portion prior to installation of the valve system 11.
[0110] With the valve system 11 in place, carbon dioxide gas or
liquid is loaded into the compartment 8 by means of a needle
injection through the rubber bung 6, causing its adsorption into
the activated carbon 18 in the compartment 8. The carbon dioxide
gas pressure in the compartment 8 equalizes the pressure in the
canister 1 surrounding the substance to be dispensed via the
one-way valve 7.
[0111] In use of the canister 1, the carbon dioxide pressure
generated by the pressure pack system of the invention will, when
the operating button 14 is depressed, urge the substance being
dispensed from the canister 1 via the tube 16 and the valve system
11 and the discharge port 17.
[0112] With reference to FIG. 3, there is shown a canister 31
incorporating a pressure pack dispensing system of the invention.
The canister 31 comprises a cylindrical main body portion 32, an
integrally formed circular base portion 33 of concave shape
(external view) and a circular top portion 34 of convex shape
(external view), all made of an aluminum alloy material.
[0113] Positioned centrally of the top portion 34 is an aperture 35
and sealingly held therein is a dispensing block 36 having a main
passageway 37 therethrough and an associated valve 38 for allowing,
in use, product to be dispensed from the interior of the canister.
Biasing means, for example a spring (not shown), urges the valve
towards a closed position.
[0114] The passageway 37 is linked at one end to a reciprocatable
valve actuating hollow tube 39 and at the other end to a `dip` tube
40 extending into the main body portion 32.
[0115] An operating cap 41 is positioned over the dispensing block
36 and movement (depression) thereof towards the body portion 32
actuates the hollow tube 39 and causes opening of the valve 38.
[0116] A further passageway 42 in the dispensing block 36 has an
opening adjacent the operating cap 41 and extends into the interior
of a canister 44 attached to the dispensing block 36 and forming an
integral unit therewith.
[0117] A one-way valve 45 is present in the passageway 42 to allow
flow of fluid into the container 44 but not vice versa. A further
one-way valve 46 is present in the base of the container 44 to
allow flow of carbon dioxide from the container 44 and into the
canister 31 when the pressure in the canister falls below that of
the container 44.
[0118] In assembling the canister including the pressure pack of
the invention, the dispensing block 36 (to include the dip tube 40
and the linked container 44) is sealingly inserted into the
aperture 35 in the canister top portion in a single assembly
step.
[0119] The canister is filled with liquid product to be dispensed
via a needle inserted into the hollow tube 39 and operates to open
the valve 38 against the action of the biasing means in order to
allow the liquid to flow through the passageway 37 and dip tube 40
and fill the canister up to the product level 47.
[0120] The container 44 is pre-packed with activated carbon held
under an atmosphere of carbon dioxide since its production and
additionally pre-flushed with carbon dioxide. After insertion of
the dispensing block, etc into the aperture 35 and product into the
canister interior, a source of carbon dioxide gas under pressure is
attached to the passageway 42 for pressurization of the container
44 via the one-way valve 46 and to cause the adsorption of the
carbon dioxide onto the activated carbon in the container. The
presence of the further one-way valve 46 allows the carbon dioxide
to pressurize the head space above the product in the canister 31
until the respective pressures are substantially equalized.
[0121] The operating cap 41 is then fitted over the dispensing
block and the aerosol canister is ready for use. Depression of the
operating cap 41 moves the tube 39 and actuates the valve 38 to
allow product to pass up the dip tube 40 and be dispensed from the
canister via the passageway 37, the tube 39 and a passageway (not
shown) in the operating cap 41 to a nozzle 48 in the cap 41, all
under the carbon dioxide gas pressure present in the head
space.
[0122] Resulting loss of carbon dioxide pressure in the head space
is replenished by an automatic flow of gas from the container 44
via the one-way valve 46. Pressure in the container 44 itself is
maintained by desorption of further gas from the activated
carbon.
* * * * *