WO2009039565A1

WO2009039565A1 - Valve housing for an aerosol valve assembly

Info

Publication number: WO2009039565A1
Application number: PCT/AU2008/001414
Authority: WO
Inventors: Max Reynolds
Original assignee: Max Reynolds
Priority date: 2007-09-25
Filing date: 2008-09-24
Publication date: 2009-04-02

Abstract

A valve housing (16) for an aerosol valve assembly (10) for an aerosol container having a compressed gas propellant in a head space above a product to be dispensed, whereby the valve housing (16) includes; a valve chamber (20) through which product being dispensed passes and a vapor tap (23) in communication with the head space of the container for introducing gas from the head space into the valve chamber (20) to mix with product being dispensed; wherein the vapor tap has a diameter of 100µm or less.

Description

VALVE HOUSING FORAN AEROSOLVALVE ASSEMBLY

The present invention relates to valve housing for a valve assembly for use with an aerosol dispenser using a compressed gas as a propellant. In particular, the present invention relates to valve housing for use with an aerosol dispenser using Nitrogen as a prope\iant The present invention also relates to a valve assembly including the valve housing.

BACKGROUND OF THE INVENTION

Aerosol dispensers are well known and typically include a container holding a liquid, powder gel, foam, oil or other product to be dispensed. The container also holds a propellant under pressure which provides force to expel the product from the container. The principle propellants used in aerosol containers are gaseous hydrocarbons which when under the pressure in an aerosol container, are present mainly as a liquid. The product is typically dissolved and/or dispersed in the liquid hydrocarbon. The container has a head space which is filled by the gaseous hydrocarbon. As the product and liquefied hydrocarbon are dispensed from the container and the product level falls in the container, more of the liquid propellant turns to gas thereby keeping the pressure within the container relatively constant over the lifetime of the container. This relatively constant pressure typically allows a consistent spray performance to be obtained. Compressed gases may also be used as propellants. Compressed gases are not present as a liquid and are principally present in compressed gaseous form in the head space of the container. When the aerosol nozzle is actuated, the pressure of the gas "pushes" the product from the can. As the product level falls, there is a decrease in pressure as the head space increases in volume. This decrease in pressure results in a decrease in spray performance over the lifetime of the container. Spray characteristics which may be influenced include spray pattern, particle size and the like. In particular, spray particle size is dependent upon pressure and actuator design. As the pressure drops, the particle size increases. In some instances, the particle size increases such that the aerosol spray is ineffective for its intended use. Further, the gas supply is often exhausted before the entire product has been dispensed. The above decrease in performance with a decrease in pressure is particularly problematic when nitrogen is the propellant. The reason for this is that carbon dioxide and nitrous oxide may be at least partially soluble in a liquid product. In this case, as the liquid level decreases, nitrous oxide which can also be a health risk if inhaled or carbon dioxide comes out of solution and enters the head space, thereby at least partially alleviating the drop in pressure.

In the light of the above difficulties with compressed gas propellants, liquefied hydrocarbons have been the propellant of choice in the aerosol industry. Compressed gas propellents have however found use in applications such as fire extinguishers where the flammability of the hydrocarbons prevents their use and products such as furniture polish which does not require small droplet break up.

A significant disadvantage of liquefied hydrocarbons, apart from their flammability is that they are detrimental to the environment and significantly contribute to green house gasses. They change into Ozone and carbon dioxide with a volume 3 times greater than the original aerosol. Ozone is also a health hazard causing upper respiratory and lung diseases. Thus, it is desirable to be able to replace liquefied hydrocarbon propellants with compressed gas propellants and in particular nitrogen. However, in light of the above disadvantages, such replacement is not considered to be commercially or practically viable. It is therefore an object of the present invention to provide a valve housing and valve assembly for use with a compressed gas propellant in an aerosol container which may at least partially overcome the above disadvantages or provide the public with a commercial or useful choice.

SUMMARY OF THE INVENTION According to a first broad form of the invention, there is provided a valve housing for an aerosol valve assembly for an aerosol container having a compressed gas propellant in a head space above a product to be dispensed, whereby the valve housing includes; a valve chamber through which product being dispensed passes and a vapor tap in communication with the head space of the container for introducing gas from the head space into the valve chamber to mix with product being dispensed; wherein the vapor tap has a diameter of 100μm or less. It will be appreciated that the valve housing of the invention may be used with any suitable valve assembly for an aerosol container. These assemblies include any type of assembly whereby product is dispensed though a valve housing. Typically, the product outlet of a valve chamber is sealed by a gasket. When the actuator is depressed it allows product and gass to be forced out of the container by the pressure of the compressed gas. The product outlet may be associated with a valve stem in the case of a male type valve or a valve seat in the case of a female type valve.

The use of a vapor tap in a valve housing used in a valve assembly for use with liquefied gas propellents is known. Such vapor taps are used to facilitate mixing of the propellent and fluid being dispensed and can reduce particle size. The diameter of these known vapor taps is in the range of 300μm to 600μm and they are obtained by laser drilling using a CO₂ laser. The use of conventional vapor taps with valve assemblies for use with compressed gas propellants simply leads to a rapid loss of propellant and drop in pressure. In practice, the level of propellant required to maintain a workable pressure is lost when about one third of the fluid material remains in the container. It is generally believed by those of skill in the aerosol arts that any use of a vapor tap with a compressed gas would lead to an unacceptably rapid decrease in pressure. The present inventor has surprisingly and unexpectedly observed that when a valve housing of the invention is used in a valve assembly for dispensing fluid from an aerosol container using a compressed gas as a propellant, it is possible to achieve a substantially uniform particle size throughout the lifetime of the container. The present inventor believes that such consistency has not been able to be achieved.

The vapor tap may suitably be located in any part of the valve housing, providing that the vapor tap allows for communication between the head space and the valve chamber such that gas may pass from the head space through the vapor tap and into the valve chamber to mix with product being dispensed. Typically the valve housing has a side wall and the vapor tap is located in the side wall. The vapor tap is typically drilled using a laser capable of drilling a spot size

100μm or less. Preferred laser systems are a triple YAG laser operating at 355nm and a UV copper vapor laser operating at 255nm. Hole sizes varying between about 10μm to about 100μm can be drilled. A preferred technique for drilling holes is the technique of trepanning which is known to those of the laser drilling arts.

The valve housing of the present invention may find particular application for use with nitrogen as a propellant.

According to a further broad form of the invention there is provided a valve assembly for an aerosol container having a compressed gas propellant in a head space above a product to be dispensed, the valve assembly including a valve housing having a valve chamber through which product being dispensed passes and a vapor tap in communication with the head space of the container for introducing gas from the head space into the valve chamber to mix with product being dispensed; wherein the vapor tap has a diameter of 10Oμm or less.

According to a further broad form of the invention, there is provided an aerosol container having a compressed gas propellant above a product to be dispensed, the container including a valve assembly including a valve housing having a valve chamber through which product being dispensed passes; and a vapor tap in communication with the head space of the container for introducing gas from the head space into the valve chamber to mix with product being dispensed; wherein the vapor tap has a diameter of 100μm or less.

The valve housing and assembly of the present invention may be used in the construction of aerosol containers for the dispensation of any suitable product.

Preferred products are those whose use is under conditions where it is preferred that the propellant is neither flammable nor toxic. Such applications include but are not limited to cooking oil, bomb release insecticides, fly sprays, industrial sprays, air fresheners, deodorants, oven sprays, oral sprays, medicinal and therapeutic sprays and the like.

The aerosol container of the invention typically has a dip tube diameter within the range of about 0.5mm to about 4mm. The container has an actuator with an exit orifice typically having a diameter of between about 0.3mm to about 4mm.

Typical pressures within a full aerosol container are between about 800KPa to about 1200KPa. It will be appreciated by those of ordinary skill in the art that the above parameters may be varied depending upon the desired spray profile, density and viscosity of product and the like.

It will also be appreciated that the spray particle size will vary with the application. Typically, 'space sprays' such as fly sprays and the like have particle sizes of between about 30 to 50 micron. Preferably at least about 75% most preferably at least about 95% of such a spray is delivered between these particle sizes.

BRIEF DESCRIPTION OF THE FIGURE

Figure 1 shows a cross section of a preferred aerosol can of one form of the invention; and Figure 2 shows a cross section of the top section of a valve assembly for an aerosol can.

DETAILED DESCRIPTION OF THE FIGURE

Figure 1 shows a preferred aerosol can 2 of the present invention. The can

2 has a valve assembly 10 that will be explained in further detail with respect to Figure 1 below. The can 2 has a dip tube 3 attached to the lower portion of the valve assembly 10. A dispensing nozzle 4 with an exit orifice 5 is attached to the upper portion of the valve assembly 10.

Figure 2 shows a cross section of the valve assembly 10 for the aerosol can shown in Figure 1. The assembly 10 has a steel mounting cup 11 which is crimped at the periphery thereof to the can walls. A rubber gasket 12 provides a seal between the mounting cup 11 and the can. The valve assembly 10 includes a valve stem 14, a valve gasket 15, a valve housing 16 and a spring 17. The valve stem 14 extends though a central opening within the mounting cup 11 and is moveable relative to the mounting cup 11 and the valve housing 16 between a closed position and a dispensing position. The valve stem is biased towards the closed position by spring 17. The valve housing 16 has a valve chamber 20 for receiving product to be dispensed. Product can enter the valve chamber 20 from the dip tube through passageway 21 in the tubular lower end 18 of valve housing 16. The valve stem

14 has a dispensing passage 22 located in the upper portion thereof. The dispensing passage 22 is in communication with the dispensing nozzle 4. The valve stem 14 has a dispensing orifice located in the side thereof (not shown).

When the valve stem 14 is in the closed position, the dispensing orifice is sealed by valve gasket 15. When the valve stem 14 is depressed into the dispensing position, the seal is broken and the dispensing orifice is in fluid communication with valve chamber 20 and product can flow into the dispensing passage 22.

The valve housing 16 also includes a vapor tap 23 located in the side wall 24 of the valve chamber 20. The vapor tap 23 is a narrow bore hole having a diameter of between about 10μm to about 100μm. It will be appreciated that in use, the valve housing 16 is located in the head space of the aerosol can. The vapor tap 23 is therefore in communication with the gas in the head space. When product is being dispensed, compressed gas in the head space of the container can enter the valve chamber 20 through vapor tap 23 and mix with the product therein.

Example A valve assembly illustrated above was mounted to a convention aerosol can and charged with nitrogen compressed gas as a propellant to an initial pressure of 1000KPa. The product in the can was cooking oil. The diameter of the vapor tap was 10μm.

The particle size of the aerosol spray was between about 50μm to about 80μm.

The particle size and pressure within the can over the lifetime of the can is shown in Table 1.

TABLE 1

It will be appreciated that the valve housing and assembly of the present invention allows compressed gases and in particular nitrogen to be used as propellants in aerosol containers without the observed decrease in spray performance over the life time of the container as seen with conventional valve assemblies. This enables compressed gas propellents to be used in a wider variety of applications. Increased usage of compressed gas propellants also offers significant environmental advantages as it can reduce the levels of hydrocarbons released into the atmosphere. A further advantage of a compressed gas sch as nitrogen is its lack of flammability and toxicity. Still further, nitrogen is a renewable resource.

It will be appreciated that various changes and modifications may be made to the invention as described and claimed herein without departing from the spirit and scope thereof.

Claims

1. A valve housing for an aerosol valve assembly for an aerosol container having a compressed gas propellant in a head space above a product to be dispensed, whereby the valve housing includes; a valve chamber through which product being dispensed passes and a vapor tap in communication with the head space of the container for introducing gas from the head space into the valve chamber to mix with product being dispensed; wherein the vapor tap has a diameter of 100μm or less.

2. The valve housing of claim 1 , wherein the vapor tap has a diameter of between about 10μm and about 50μm.

3. The valve housing of claim 1 or claim 2, wherein the valve housing has a side wall and the vapor tap is located in the side wall.

4. A valve assembly for an aerosol container having a compressed gas propellant in a head space above a product to be dispensed, the valve assembly including a valve housing having; a valve chamber through which product being dispensed passes and a vapor tap in communication with the head space of the container for introducing gas from the head space into the valve chamber to mix with product being dispensed; wherein the vapor tap has a diameter of 100μm or less.

5. The valve assembly of claim 4, wherein the vapor tap has a diameter of between about 10μm and about 50μm.

6. The valve assembly of claim 4 or claim 5 wherein the valve housing has a side wall and a bottom wall and the vapor tap is located in the side wall.

7. An aerosol container having a compressed gas propellant in a head space above a product to be dispensed, the container including a dip tube, a dispensing orifice and valve assembly with a valve housing having; a valve chamber through which product being dispensed passes and a vapor tap in communication with the head space of the container for introducing gas from the head space into the valve chamber to mix with product being dispensed; wherein the vapor tap has a diameter than 100μm or less.

8. The valve assembly of claim 4, wherein the vapor tap has a diameter of between about 10μm and about 50μm.

9. The valve assembly of claim 4 or claim 5 wherein the valve housing has a side wall and the vapor tap is located in the side wall.

10. The container of claim 5, wherein the compressed gas is nitrogen.

11. The container of claim 6, wherein the particle size of dispensed aerosol particles is between about 30μm to about 80μm over at least 90% of the lifetime of the container.

12. The aerosol container of any one of claims 7 to 11 wherein the dip tube has a diameter between about 0.5mm to 4mm.

13. The aerosol container of any one of claims 7 to 12 wherein the exit orifice has a diameter between about 0.3mm to about 4mm.

14. The aerosol container of any one of claims 7 to 13, wherein the aerosol container of between about 800KPa to about 120KPa.