GB2233395A

GB2233395A - Improvements in or relating to aerosol type dispensers.

Info

Publication number: GB2233395A
Application number: GB8914442A
Authority: GB
Inventors: Hazel Pool; Arthur Richard Speed
Original assignee: Reckitt and Colman Products Ltd
Current assignee: Reckitt Benckiser Healthcare UK Ltd
Priority date: 1989-06-23
Filing date: 1989-06-23
Publication date: 1991-01-09
Anticipated expiration: 2009-06-23
Also published as: ATE93477T1; DK0479796T3; HK1008003A1; FI916034A0; EP0479796A1; FI91737C; AU5660490A; NO915026D0; EP0479796B1; JPH04505903A; DE69002949D1; ES2044589T3; IE902249L; IE902249A1; DE69002949C5; FI91737B; PT94445A; HK1008002A1; GB2233395B; CA2060662C

Abstract

Dispensing arrangements, comprising a gas-pressurized container for a material to be dispensed with a valve actuable to open a discharge passage through the valve and through a valve and a valve actuator to an actuator discharge outlet, are well known in the art. The invention proposes a non-liquefied gas-pressurized dispensing arrangement capable of being used with relatively low initial gas pressures, and of discharging a relatively high percentage of the dispenser contents with an acceptable spray pattern. The proposed dispensing arrangement attains these advantages by arranging the cross-sectional area of the valve port (17c) to be many times greater than the cross-sectional area of the actuator outlet (22a). In one recited embodiment the actuator outlet has a cross-sectional area in the region of 0.049 mm<2> whilst the total cross-sectional area of the valve ports, the valve having four ports, is some sixteen times greater.

Description

"IMPROVEMENTS IN OR RELATING TO DISPENSERS" This invention relates to dispensers and, more specifically, to the dispensing of flowable materials from gas-pressurised containers.

It is well known in the art to dispense flowable materials from a container having a valve-controlled outlet by charging the container with the flowable material and a pressurising gas, whereupon the gas forms a head space above the liquid. To dispense the flowable material the container is placed in a position where the inlet to the valve opening is below the material/gas interface whereupon, when the valve is opened, the pressurised gas propels the flowable material through the valve to discharge.

When the container is to be used erect the valve is conveniently located in the upper regions of the container and a dip tube within the container extends from the valve to the lower regions of the container so that, whilst the container is erect, the dip tube inlet is below the material/gas interface until substantially the whole of the material content of the container has been dispensed.

In one well known and widely used dispensing arrangement the valve is opened by depressing an actuator and the valve port opens to a chamber within the actuator from which the material is dispensed through a discharge outlet in the actuator.

Such a material dispensing arrangement is, hereinafter, referred to as "a dispensing arrangement of the type defined".

It should be noted that in a dispensing arrangement of the type defined the material flowing through the dip tube passes through a first restriction, defined by the valve port, and then through a second restriction defined by the actuator discharge outlet. Other restrictions may be imposed by the valve housing, tail piece and dip tube.

In some constructions for dispensing arrangements of the type defined the valve may include more than one valve port and/or the actuator may have more than one discharge outlet.

Throughout this specification the term " cross-sectional area of the valve port" shall mean the cross-sectional area of the valve port in a single valve port arrangement and the sum of the cross-sectional areas of all the valve ports in a multiport valve port arrangement and the term "cross-sectional area of the discharge outlet" shall mean the cross-sectional area of the actuator outlet in a single actuator outlet arrangement and the sum of the cross-sectional areas of all the actuator outlets in a multi-outlet arrangement.

One inherent problem with dispensing arrangements of the type defined resides in providing a pressurising gas capable of maintaining sufficient pressure throughout the life of the container as to propelling at least the greater part of the material content from the container.

The above problem appeared to have been overcome by the use of the so-called "liquefied gases", that is to say gases at normal temperature and pressures which condense at relatively low pressures above atmosphere, generally between one and twelve atmospheres gauge. This is often reduced to the order of three atmospheres gauge by the presence of other components in the formulation. When such liquefied gases are used in a dispensing arrangement of the type defined vaporization of the liquefied gas establishes the gas space at a pressure sufficient to propel the material contents out of the container and, as material content is discharged and the volume of the gas space increases, the liquefied gas vaporizes within the container thus to maintain a substantially uniform material-propelling gas pressure in the head space until substantially all the material content has been discharged.

The liquefied gases in being readily usable with a wide range of products, in allowing containers to be charged with material contents often in excess of 70% of the container volume and in allowing the use of relatively cheap low pressure container in a wide variety of materials, have substantially dominated the dispensing industry for the past forty years.

However, the liquefied gases, and in particular the chlorofluorocarbons (CFCs), have now been recognised as harmful to the environment or having other undesirable features and the dispensing industry has been forced to seek alternative systems, essentially using compressed gases virtually all of which remain in their gaseous phase for all operating parameters of the container (hereinafter referred to as "nonliquefied gases").

Gases obey the gas laws, at stable temperature the pressure reduces proportional with increase in volume and for non-liquefied gases the initial gas content must be sufficient to maintain a pressure adequate to propel an acceptable volume of the container material content up the dip tube and through the valve.

As the gas pressure depends upon the volume of the material content in the container the container with its valve and actuator arrangement must be designed to safely withstand the initial high gas pressure as will exist when the container is fully charged with its material content.

It is however believed that by careful design of the dispensing arrangement and by reducing the charge of material content to not more than 70%, and more preferably not more than 65%, of the container volume a dispensing arrangement can be designed to meet the above propellant requirements with the initial gas pressure little more than 100 p.s.i.

However, the liquefied gases used with certain material contents, solvents for material contents or additives offer a further advantage in that the said liquefied gases can be dispersed through the material content in the container.

As the material content passes through the actuator outlet the entrained liquefied gas will vaporize, breaking up the discharging material into discrete particles and blowing the particles apart to form a relatively constant spray pattern.

This advantage is particularly useful when the material content is a liquid, whereupon vaporization of the liquefied gas leaving the actuator outlet breaks the liquid material content into fine droplets, particularly advantageous for many applications such as hair spray, air fresheners and liquid insecticides. Additional breakup can be achieved by bleeding propellent gas into the liquid stream from the vapour phase.

It will now be appreciated that whilst, as stated above, it is possible to design a container of the type defined to allow non-liquefied gases to propel an acceptable part of the material content to discharge such a design cannot, with the current state of the art, provide acceptable discharge characteristics of the material content propelled through the actuator outlet.

The reasons for this are, as will be apparent from the foregoing description, that the pressure of the non-liquefied gas propellant will be continuously reducing as material content is discharged from the container and without liquefied gas in the material being dispensed there can be no " blowing apart" of the material being dispensed. This reduction in pressure also reduces the flow rate of the material being dispensed. The present invention seeks to provide a dispensing arrangement of the type defined capable of affording a substantially constant discharge characteristics for a material being dispensed for the greater part of the life of the container.

According to the present invention there is provided a dispensing arrangement of the type defined intended for use with non-liquefiable gases characterised in that the crosssectional area of the valve port is greater than the crosssectional area of the actuator outlet.

Preferably the cross-sectional area of the valve port is greater than twice the cross-sectional area of the actuator outlet, more preferably the cross-sectional area of the valve port is greater than five times the cross-sectional area of the said actuator outlet and most preferably the said crosssectional area of the valve port is greater than ten times the cross-sectional area of the actuator outlet.

In a preferred embodiment in accordance with the invention the actuator outlet has a diameter of 0.25 mn, giving 2 a cross-sectional area in the region of 0.049mm2and the valve port comprises four ports, each having a diameter of 0.5mn 2 giving a total cross-sectional area of 0.7854 mm.

The invention will now be described further, by way of example, with reference to the accompanying drawings in which, Fig. 1 shows a vertical cross-section through a valve system for a dispensing arrangement in accordance with the present invention, Fig. 2 shows a view of the valve port arrangement, on an enlarged scale with respect to Fig 1, with the valve port open, and Fig. 3 shows, graphically, how the discharge rates through a fixed valve port differ with different actuator outlets for a liquid material having a viscosity of 510 cps.

Referring to Figs 1 and 2 the valve system is supported by a conventional cup 11, intended to close the opening in a container C, and generally comprises a body 12, rigidly crimped to the cup 11 within the container C, with an actuator/valve assembly supported by the body 12 and axially displaceable relative thereto.

The body 12 is a body of revolution defining a large bore 13 with a small through bore 14, axially aligned with and opening to the bore 13. A dip tube T is attached to the outer cylindrical surface of the wall defining the bore 14 and extends into the container C to open in the lower regions of the said container C.

The body 12 includes an annular flange 15 at that radial end to which the bore 14 opens and an annular, flexible, resilient gasket 16 has its radially outermost parts clamped between the flange 15 and the cup 11.

A valve stem 17, with a blind bore 17a, extends through a clearance bore in the cup 11, through the bore in the gasket 16, and terminates in an integral annular block 1Tb within the bore 13, having a diameter larger than the diameter of the bore in gasket 16. A coil compression spring 18 acts on the block 17b and continuously urges the block 17b against the gasket 16. The valve stem 17 has an actuator button 19 secured thereon.

The valve stem is a friction fit in the bore of the gasket 16 and includes a valve port, defined by a radial opening 17c in the wall of the valve stem 17 opening to the bore 17a. The valve port 17c is so located from the block 17b that said valve port 17b is closed by the gasket 16 when the gasket is unflexed (as shown in Fig 1) and is open to the bore 13 when the actuator button 19 is depressed, thereby forcing the valve stem 17 into the body 12 and flexing the gasket 16 inwardly of the container as shown in Fig 2.

At its end entered into the actuator button 19 the bore 17a of valve stem 17 opens to a chamber 20, which may include a conventional swirl block 21, and an exit passage 19a from the chamber 20 is closed by an insert plate 22 in the actuator which has an aperture 22a there through defining the actuator discharge outlet.

The valve arrangement described thus far is of a conventional design, with the actuator button 19 released the spring 18 urges the valve block 17b and stem 17 upwardly to the position shown in Fig. 1 where the gasket 16 is sealing the valve port 17c.

When the actuator button 19 is depressed the block 17b is displaced downwardly away from the gasket 16, the gasket 16 deflects into the bore 13 exposing the valve port 17c and, under the action of the propellant pressure gas in container C, container contents are driven up the dip tube T into the bore 13 and therefrom through the valve port 17c, up the blind bore 17a to the chamber 20 and therefrom along the passage 19a and through the actuator outlet 22a to discharge.

In the conventional arrangement for non-liquified gases the cross-sectional area of the valve port 17c would be similar to the cross sectional area of the actuator outlet 22a but, in accordance with the present invention, this relationship is disregarded and the actuator outlet will have a very much smaller cross sectional area than the valve port.

Thus, for the illustrated example using a nonliquefied gas, such as nitrogen, a liquid material content charging 50% to 60% of the container volume and the gas space charged to an initial pressure of 100 p.s.i., the actuator outlet 22a may conveniently have a cross-sectional area of 2 0.049 mm 2and the valve port, conveniently four ports 17c on a common plane at right angles to the axis of the stem 17, may 2 conveniently have a cross sectional area of 0.78 mm Such proportions have been shown in practice to allow a substantially uniform discharge rate throughout substantially the whole of the life of the container, with a relatively fine droplet size in a wide spread distribution spray pattern compatible with that obtainable by a liquefied gas dispensing arrangement.

Fig. 3 shows, graphically, the effects of varying the cross-sectional area of the actuator outlet relative to a fixed valve port, the rate of discharge in grams is plotted vertically and the number of ten second sprays obtainable is plotted horizontally.

The fixed valve port was defined by four valve ports, each of 0.5 millimetre diameter, giving a total cross-sectional 2 area of 0.79 mm2.

Table 1 shows the arrangements of the actuator outlet cross-sectional areas.

TABLE 1 GRAPH. NUMBER DIAMETER CROSS-SECTIONAL OUTLET AREA OF OUTLETS OF OUTLET AREA OF OUTLET RELATIVE TO (mm) ( k VALVE PORT AREA A 1 0 6 0.283 .361 B 1 0.5 0.196 .25 C 1 0.45 0.159 .203 D 1 0.4 0.126 .16 E 1 0.3 0.071 .09 F 1 0.25 0.049 .0627 Fig. 3 clearly shows that as the cross-sectional area of the actuator outlet is reduced the rate of distribution became more uniform and, contrary to what one would expect with a continuously falling propellant gas pressure, Graphs E and F gave substantially uniform rates of discharge for more than 90% of the material contents.

It was also observed that as the cross-sectional area of the valve port increased relative to the cross-sectional area of the actuator outlet the more consistent became the area covered by the spray pattern throughout the life of the container.

Table 2 shows the result of one such such trial carried out with a constant actuator outlet cross-sectional 2 area of 0.49 inn and varying the cross-sectional area of the valve port.

TABLE 2 Cross-sectional Spray area Spray area Spray area area of covered with covered with covered with valve port full container k full container sq. millimetres sq. cms. container full by sq.cms k full 0.7068 422 123 29% 0.1590435 638 232 36% 0.19583 540 302 56% 0.282744 651 464 71% 0.39166 596 421 71% 0.7833 798 592 74% It will be noted from Table 2 that the percentage of the area of the spray button covered by the full container by the quarter full container increased with increase in the difference between the cross-sectional area of the valve part and that of the actuator outlet. As the area covered can be taken as indicative of the spray distribution, the results obtainable by utilizing valve port cross-sectional areas many times larger than that of the actuator outlet are closely comparable with the results obtainable by liquefied gas dispensers.

Claims

MAIMS

1. A dispensing arrangement of the type defined characterised in that the cross-sectional area of the valve port is greater than the cross-sectional area of the actuator outlet.

2. A dispensing arrangement according to claim 1 characterised in that the cross-sectional area of the valve port is greater than twice the cross-sectional area of the actuator outlet.

3. A dispensing arrangement according to claims 1 or 2 characterised in that the cross-sectional area of the valve port is at least five times greater than the cross sectional area of the actuator outlet.

4. A dispensing arrangement according to claim 1, 2 or 3 characterised in that the cross-sectional area of the valve port is at least ten times greater than the cross-sectional area of the actuator outlet.

5. A dispensing arrangement according to any of the preceding claims characterised in that the actuator outlet has 2 a cross-sectional area of from 0.02 mm to 0.126 rmn2

6. A dispensing arrangement according to any of the preceding claims characterised in that the actuator has a single outlet having a diameter of 0.25 mm.

7. A dispensing arrangement according to any of the preceding claims characterised in that cross-sectional area of 2 the valve port is from 0.196 mm2 to 1.57 mm.

8. A dispensing arrangement of the type defined according to any one of the preceding claims charged with a nonliquefied gas.

9. A dispensing arrangement according to claim 8 characterised in that the gas is nitrogen.

10. A dispensing arrangement according to claim 8 characterised in that the gas is carbon dioxide.

11 A dispensing arrangement substantially as hereinbefore described with reference and as illustrated in Figs. 1 and 2 of the accompanying drawings.