WO2025140943A1

WO2025140943A1 - Spray product

Info

Publication number: WO2025140943A1
Application number: PCT/EP2024/087592
Authority: WO
Inventors: Merion Evans; Louise Ombler McMaster
Original assignee: Unilever Global IP Ltd; Unilever IP Holdings BV; Conopco Inc
Current assignee: Unilever Global IP Ltd; Unilever IP Holdings BV; Conopco Inc
Priority date: 2023-12-27
Filing date: 2024-12-19
Publication date: 2025-07-03
Anticipated expiration: 2026-06-27

Abstract

A spray product comprising a liquid base composition; a propellant; and a dispenser to mix the components into an aerosol on exit from said dispenser; the propellant comprising a liquified gas propellant and a compressed gas; and the dispenser comprising a valve with a VPT in the housing; wherein a narrowed lower section of the valve stem is below the VTP in the valve housing when the valve stem is fully depressed.

Description

Spray Product

Field of Invention

The present invention is in the field of spray products, in particular spray products that require a reduced content of liquified gas propellant gas in the formulation to be sprayed.

There is a desire to minimise the quantity of hydrocarbons and other aerosol propellants emitted into the atmosphere in order to reduce global warming. Also, there is a desire to avoid the emission of gases that may harm the ozone layer, such as certain chlorofluorocarbons. These desires have led to research into spray dispensers that can operate effectively with reduced content a liquified gas propellant gas, whether hydrocarbon or other, in the formulation to be sprayed. The present invention focusses on the use compressed gas to partially replace conventional liquified gas aerosol propellant.

There are numerous publications describing aerosol products with a reduced content of liquified gas propellant.

EP 753,561 A1 (P&G, 1997) discloses an aerosol package comprising “ozone friendly” propellants, such as compressed gas or nitrogen, amongst other options.

US 8,191,739 B1 (AMREP Inc., 2012) discloses an aerosol dispenser that is pressurised by both compressed gas and liquified gas and which is suitable for foaming products.

WO 2022/012947 A1 (Unilever, 2022) discloses aerosol products having reduced VOC content wherein the propellant comprises a compressed gas and 5 to 15% by weight of a liquefied gas and wherein the pressure in the container is from 9x10⁵ to 11x10⁵ Pa.

WO 2022/013362 A1 (Unilever, 2022) discloses aerosol hair care products comprising a spraying device having a valve with a restricted tail piece of diameter 0.50 to 0.55 mm and a vapour phase tap of diameter from 0.30 to 0.34 mm. US 2023/278505 A1 (P&G, 2023) discloses spray devices for antiperspirant or deodorant compositions with a compressed gas propellant.

General Description

It is an object of the present invention to enable the production of a high quality spray with a reduced need for a liquified gas propellant gas in the formulation to be sprayed.

It is a further object of the present invention to provide a spray product using both compressed gas and liquified gas propellant gas as propellant.

It is a further object of the present invention to provide a spray product that produces a good quality spray.

It is a further object of the present invention to provide a spray product that has a low tendency for valve blockage, particularly with liquid base compositions comprising particulate matter.

In a first aspect of the invention, there is provided a spray product comprising (i) a liquid base composition; (ii) a propellant; and (iii) a dispenser to mix components (i) and (ii) into an aerosol on exit from said dispenser (iii); the propellant (ii) comprising a liquified gas propellant and a compressed gas; and the dispenser (iii) comprising a reservoir for components (i) and (ii); a valve comprising a valve housing comprising a vapour phase tap (VPT) and a restricted tail piece (RTP), the valve housing containing a valve stem and a valve spring located around a narrowed lower section of the valve stem; a valve chamber exterior to the valve stem and within the valve housing; a means to transfer the liquid base composition to the valve housing via the RTP; a stem orifice between a valve stem central channel and the valve chamber; an actuator button associated with the valve stem, pressure upon which moves the valve stem and opens the valve by unblocking the stem orifice; wherein, opening of the valve allows entry into the valve chamber of liquid composition via the RTP and propellant via the VPT; and wherein opening the valve entails the valve stem being lowered; the narrowed lower section of the valve stem being below the VTP in the valve housing when the valve stem is fully depressed. A critical aspect the first aspect of the invention is the axial positioning of the VPT relative to the valve stem. It is important that the VTP is above the lower narrowed lower section when the valve is actuated, and the valve stem is depressed. I.e., it is critical that the narrowed lower section of the valve stem is completely below the VTP when the valve stem is fully depressed. In some preferred embodiments, valve stem is completely below the VTP even when the valve stem is partially depressed. Indeed, in some particularly preferred embodiments, the narrowed lower section of the valve stem is completely below the VTP both when valve stem is depressed and when it is not depressed at all.

In a second aspect of the invention, there is provided a method of topical application of a cosmetic composition comprising the use of a spray product according to the first aspect of the invention. This equates to the use of a spray dispenser as described in the first aspect of the invention for the topical application of a cosmetic composition. In this second aspect of the invention, particular benefits arise when the composition is applied to the underarm areas of the human body, due to the sensory benefits resulting from the good spray quality.

Detailed Description

Spray products of the invention are typically hand operated. In preferred embodiments, they may be used to spray household care formulations, personal care formulations or medicinal formulations. Spray products of the invention are preferably used with household care or personal care formulations and more preferably with personal care formulations, particularly those applied to the surface of the human body because of the good sensory properties of the sprays typically generated.

Herein, medicinal spray products include inhalers, products for topical treatment of skin disorders, for topical sanitization, for topical wound dressing and for topical treatment of systemic conditions, this list being non-exhaustive, but each option listed being a specific possible application of the present invention.

Herein, household care formulations include hard surface cleaners, room fresheners, laundry products and plant care products, this list being non-exhaustive, but each option listed being a specific possible application of the present invention. Herein, personal care formulations include deodorants and antiperspirants, perfumes, hair care formulations, oral care formulations, and skin care formulations including sunscreens and make-up formulations, this list being non-exhaustive, but each option listed being a specific possible application of the present invention.

Herein, orientation terms such as “horizontal/vertical”, “upper/lower” and “upward/downward”, refer to the dispenser and/or components thereof when the dispenser is oriented in an upright manner, with the exit orifice located towards the top, unless otherwise defined.

Herein, “actuation” refers to depression of the actuator button resulting in opening of the valve and release of the contents of reservoir as an aerosol.

Herein, the term “spray quality” refers to the extent of droplet breakup achieved on use of the aerosol products. It is desirably to achieve relatively high droplet breakup, such that the spray contains less than 10% of droplets greater than 100 microns in diameter and preferably less than 5% of such droplets.

Herein, the “surface of the human body” should be understood to mean the skin and any hair present thereupon.

Herein, any feature of a particular aspect or embodiment of the present invention may be utilized in any other aspect of the invention. Any feature described as ‘preferred’ should be understood to be particularly preferred in combination with a further preferred feature or features. Any feature stated as preferred in a particular aspect or embodiment of the invention should be understood to be a preferred feature in the other aspects or embodiments of the invention.

Herein, the word ‘comprising’ is intended to mean ‘including’ but not necessarily ‘consisting of’ or ‘composed of’, i.e. it is used non-exhaustively.

Herein, methods and uses should preferably be understood to be cosmetic methods/uses, i.e. non-therapeutic methods/uses. Likewise, compositions of the invention are preferably cosmetic compositions, i.e. non-therapeutic. Herein, all percentages, parts, and ratios are by weight, unless otherwise indicated.

Herein, references to an amount of a material or materials refer to the total amount of material(s) of the type indicated.

Numerical ranges expressed in the format ‘x to y’ are understood to include x and y, unless specified otherwise.

Herein, except in the specific embodiment or where otherwise explicitly indicated, all numbers in this description and claims indicating amounts of material, physical properties of materials and/or use are to be understood as modified by the word “about”.

The liquid base composition is preferably free flowing. This aids the flow of the composition through the dispenser and its atomisation to produce a high quality spray.

The liquid base composition is preferably a suspension of particulate solid in a liquid. Such compositions are particularly difficult to spray using a propellant system according to the present invention, due to potential blockage issues. This problem is addressed admirably by use of the features of the present invention, in particular the preferred and more preferred features.

The liquid base composition is more preferably a suspension of particulate solid in carrier oil. The concentration of particulate solid in the carrier oil is preferably from 5 to 40% of the liquid base composition.

In preferred embodiments, the liquid base composition is a cosmetic composition, suitable for topical application to the surface of the human body. In such compositions, it is preferred to have a suspension of a particulate cosmetic active in the carrier oil.

Herein, carrier oil is an organic material that is a liquid at ambient conditions and is non- miscible with water. The carrier oil may be composed of a mixture of component oils.

In preferred embodiments, the carrier oil may also be a masking oil, serving the purpose of reducing visible deposits when the composition accidentally comes into contact with clothing, for example. The liquid base composition is preferably anhydrous, containing less than 0.5% free water and preferably less than 0.1 % free water. Herein, “free water” is all water excluding that contained as water of hydration in any solid components present in the base compositions.

The liquid base composition is preferably non-ethanolic, containing less than 0.5% ethanol and preferably less than 0.1 % ethanol.

When employed, the carrier oil may be selected from any of those known in the art, although hydrophobic carrier oils are preferred. Suitable carrier oils include silicone oils and nonsilicone oils, although it is preferred that the liquid base composition is free of silicone oil in some embodiments.

When a particulate solid is present in the liquid base composition, it preferably has a mean particle size (D50) of less than 100 microns and preferably at least 6 microns. More preferably, the mean particle size is from 6 to 25 microns, and most preferably it is from 7 to 15 microns. This is particularly true when the particulate solid is cosmetic active. The reason for these preferences is to reduce likelihood of valve blockage.

Herein, mean (D50) particle sizes may be measured using (laser) light scattering techniques, for example using a Mastersizer instrument, obtainable from Malvern Instruments. Such instruments are set to produce a volume plot and a lens is selected in accordance with the maker's instructions to accommodate the expected particle size distribution, (or various lenses can be tested until the best lens is identified). Measurements are made by methods known in the art.

Preferred cosmetic actives, when employed, are antiperspirant actives and preferred antiperspirant actives are astringent aluminium salts, such as aluminium chlorohydrate (ACH) or aluminium sesquichlorohydrate (ASCH).

The propellant comprises a liquified gas propellant and a compressed gas. Typically, the compressed gas and a portion of the liquified gas propellant sit in a headspace above the liquid base composition. A further portion of the liquified gas propellant is typically dissolved in the liquid base propellant. The weight ratio of compressed gas to liquefied gas is preferably from 0.1 : 99.9 to 10: 90, more preferably from 0.5: 99.5 to 8: 92, still more preferably from 1: 99 to 6: 94 and most preferably from 1: 99 to 4: 96; this aiding spray quality and the longevity of spray quality.

Prior to first use, the pressure exerted by the total propellant within products according to the invention is preferably from 85 to 125 psig (0.59 to 0.86 MPa) at 25°C, these pressures assisting with good spray quality and delivery.

Preferred compressed gases are inert, i.e. unreactive materials. A particularly preferred inert compressed gas is nitrogen. Other suitable inert gases are carbon dioxide, helium and argon; although these gases are less preferred for practical reasons, in particular their greater expense.

Preferred liquified gas propellants are blends of propane, butane and/or isobutane, with the less preferred addition of an HFC.

When employed, preferred HFCs have from 2 to 4 carbon atoms. A commercially acceptable HFC is HFC-152a, otherwise known as R152a and having the chemical name 1,1- difluroethane (DFE). However, it is preferred that compositions according to the invention are free of HFC in order to minimise greenhouse gas content.

When employed, preferred HFCs have from 2 to 4 carbon atoms. A commercially acceptable HFC is HFC-152a, otherwise known as R152a and having the chemical name 1,1- difluroethane (DFE).

Other HFCs that may be employed are hydrofluoroolefins (HFOs), such as 1, 3,3,3- tetrafluoropropene, otherwise known as HFO-1234ze.

The base to propellant ratio is preferably from 30: 70 to 80: 20, more preferably from 40: 60 to 80: 20, and most preferably from 50: 50 to 80: 20. Reasons for these preferences relate to spray quality.

The reservoir for the liquid base composition and propellant is simply the internal volume of a typical aerosol can, minus the space taken by the other components of the dispenser described herein. The valve comprises a valve housing comprising a vapour phase tap (VPT) and a restricted tail piece (RTP), the valve housing containing a valve stem and a valve spring located around a narrowed lower section of the valve stem.

The VPT is an orifice in the valve housing, which allows vapour to enter the valve housing when the valve is opened (vide infra). Typically, the vapour entering through the VPT comes from a headspace above the liquid base composition in the reservoir.

The RTP is an orifice in the valve housing, typically at its bottom end leading and towards a tail piece beyond. The RTP allows liquid base composition to enter the valve housing when the valve is opened.

The valve stem is a key component of most commercial valves. Depression of the valve stem by an associated actuator button opens the valve by unblocking the stem orifice, which is a conduit between a central channel within the valve stem and the inner volume of the valve housing, known as the valve chamber. Typically, the stem orifice is blocked by a stem gasket which surrounds an upper part of the valve stem when the valve is in its closed position. The stem gasket also serves to seal off the valve chamber at its upper end. The valve chamber is the volume within the valve housing which is exterior to valve stem.

In some embodiments, the rotational alignment of the VPT and the stem orifice is important to the quality of spray generation. It is preferred that the VPT and stem orifice are radially out of alignment, preferably to an extent of from 30 to 180°, more preferably to an extent of from 60 to 180°, and most preferably to an extent of from 90 to 180°. Without wishing to be bound by theory, it is understood that adding radial movement as well as vertical movement to the vapour entering from the VPT before its exit through the stem office enhances mixing with the liquid base composition and, hence, spray quality.

The valve stem comprises a narrowed section at its lower end. This narrowed section is surrounded by the valve spring which serves to return the valve stem to its original position when downward pressure upon it is removed. The valve spring is a conventional coil spring.

The narrowed section of the valve stem is preferably tapered, reducing in diameter in a downward direction; this can aid the fitting of the valve spring thereon. In preferred embodiments, the valve spring is held away from the bottom of valve housing by one or more shelves protruding inwards from the lower inner surface of the valve housing. This serves to create a space into which the valve spring cannot descend, which can aid mixing of the propellant and the liquid base composition during actuation.

Another preferred feature is that the valve spring is never fully compressed, even when the valve stem has been depressed to its maximum extent. By leaving spaces between the coils of the spring, it is believed that mixing of the propellant and the liquid base composition may be enhanced (during actuation of the valve).

The outer diameter of the narrowest part of the section is preferably from 50 to 80% that of the widest part of the valve stem outer diameter, ignoring amy splines thereon (vide infra). This creates space for optimal mixing of the liquid base composition and the propellant and subsequent good quality spray generation.

The means to transfer the liquid base composition to the valve housing via the RTP preferably comprises a dip tube. This is attached to the tail piece of the valve housing and serves to transfer the liquid base composition from the bottom of the reservoir to the valve chamber via the RTP. This is a common feature of many aerosol dispensers.

Herein, the diameters of the VPT, RTP and stem channel are the minimum cross-sectional distances across these channels. Each of these channels is preferably cylindrical and may be of uniform diameter or tapered (tapered being the preferred option for the VTP and the stem orifice).

The VPT is preferably of diameter from 0.2 to 0.9 mm, more preferably from 0.2 to 0.6 mm and most preferably from 0.3 to 0.5 mm.

The RTP is preferably of diameter from 0.2 to 1.2 mm, more preferably from 0.4 to 0.7 mm and most preferably from 0.45 to 0.65 mm.

The ratio of the diameters of the VTP and RTP is preferably from 1 : 2 to 1 : 1 , more preferably from 1: 1.5 to 1: 1, and most preferably from 1 : 1.6 to 1: 1: 1.2. The ratio of the areas of the VTP and RTP is most preferably from 1: 1.63 to 1: 1.244. The stem orifice is preferably of diameter from 0.2 to 0.6 mm and more preferably from 0.3 to 0.5 mm.

The above preferred orifice sizes and ratios aid with the quality of spray generation and sometimes the longevity of good quality spray generation, bearing in mind the loss of compressed gas on each actuation of the dispenser. This is particularly true for the VTP to RTP ratio, where it is preferred that the RTP diameter is equal to or greater than the diameter of the VTP. In this way, the quantity of base liquid composition entering the valve chamber can be kept relatively high relative to the quantity of vapour. This leads to enhanced mixing and, hence, improved spray quality. It can also enhance the longevity of the spray product since there is a danger that the quantity of propellant, in particular the compressed gas, on each actuation is reduced relative to the quantity of liquid base composition released.

In preferred embodiments, the valve housing, containing the valve stem and the valve spring, and a stem gasket are crimped onto a valve cup, which is in turn crimped onto an opening in the reservoir, together with a cup gasket, the stem gasket and the cup gasket providing a gas-tight seal between the associated components.

In preferred embodiments, the valve stem comprises one of more vertical splines protruding radially from its outer surface at a position above the narrowed lower section of said valve stem. These serve to enhance the mixing of the vapour entering the valve chamber via the VPT and the liquid base composition entering via the RTP, thereby enhancing spray quality. Without wishing to be bound by theory, it is understood that the vertical splines increase the proportion of vertical movement of the mixture produced from the vapour from the VTP and the liquid base composition entering via the RTP and that this enhances breakup of the liquid base composition and hence spray quality.

The radial alignment of the vertical splines relative to the VPT may lead to improved spray quality. It is preferred that the VPT is radially aligned to penetrate the valve housing between the vertical splines protruding from the outer surface of the valve stem above its narrowed lower section. Enhanced mixing of the propellant and liquid base composition is believed to result. In an alternative embodiment, vertical splines extend radially inwards from the inner surface of the valve housing. This has all the benefits referred to for the splines protruding radially outwards from the outer surface of the valve stem referred to above. In addition, it is easier to achieve radial alignment of the VPT between the splines, which is a particularly preferred feature in this alternative embodiment.

In particularly preferred embodiments, the vertical splines referred to in the paragraph immediately above protrude at least 50% of the remaining radial distance towards inner surface of the valve housing.

In preferred embodiments, the spray produced by the dispenser is a fine spray having a Sauter mean droplet size (D[3,2]) of less than 100 microns, preferably from 10 to 100 microns, more preferably from 10 to 70 microns, and most preferably from 10 to 60 microns.

;ific Embodiment and further detailed

The invention will now be further described by reference to a specific embodiment. The following figures illustrate this embodiment. The specific embodiment is intended to clarify the invention but not to limit the invention.

The following descriptions is of particular elements of the dispenser (1) each being suitable for use with the present invention. Each may be used with each of the other features of the spray product herein described both independently and collectively (including pairings of any two or more features).

Figure 1 is a vertical cross-section of a valve (2), valve cup (3) and other components (described further herein). In this Figure, the valve (2) is in its closed position.

Figure 2 is a is a cross-section as in Figure 1 , but with the valve in its open position.

Figure 3 is an angled view of a valve housing (4) from the top.

Figure 4 is a perspective view of a valve stem (5).

Figure 5 is a horizontal cross-section through the valve at level of the VTP (17). As mentioned above, Figure 1 shows the valve (2) held within a valve cup (3) with the valve (2) in its closed position. In this closed position, a stem orifice (6) is blocked by a valve gasket (7). The valve gasket (7) also serves to seal off a valve chamber (8) present within a valve housing (4) and yet exterior to a valve stem (5).

When the valve is opened (as in Figure 2), the stem orifice (6) serves as a conduit between a valve stem central channel (5CC) and the valve chamber (8). The valve stem central channel (5CC) allows the mixture entering it to pass upwards to an exit orifice (not illustrated) through which the aerosol spray is emitted.

Many of the features described in the following paragraphs appear in both Figure 1 and Figure 2.

The valve stem (5) comprises three sections. At its top, there is a valve stem pipe (5P) surrounding the valve stem central channel (5CC). Below the valve stem pipe (5P) there is a wider section (5W) of diameter such that it extends to relatively close to the inner surface of the valve housing (4) (vide infra). Below the wider section (5W) of the valve stem (5) there is a narrowed section (5N) which is tapered, reducing in diameter in a downward direction. The narrowed section (5N) may be described as frustoconical in shape.

Surrounding the narrowed section of the valve stem (5N) and extending somewhat below and beyond there is a valve spring (9). This serves to return the valve stem (5) to its original position when downward pressure upon it is removed. Vertical movement of the valve spring (9) is prevented at its lower end by shelves (10) protruding inwards from the lower inner surface of the valve housing (4). These shelves (10) are most clearly illustrated in Figure 3 and the lower end of the valve spring (9) sits upon these as illustrated in Figures 1 and 2. These shelves (10) create a space (11) within the valve chamber (8) into which the valve spring (9) cannot descend.

The valve housing (4) is illustrated in Figures 1 , 2, and 3. At its top, there are multiple castellations (12) which enable the valve housing (4) to be held firmly in place when the valve housing (4) and the stem gasket (7) are crimped onto the centre of the valve cup (3).

In the bottom of the valve housing (4) there is a narrow orifice known as a restricted tail piece (RTP) (13). The RTP (13) is a conduit between the valve chamber (8) and a downwardly projecting tail piece (14) that bears a dip tube (15). The dip tube (15) extends from the tail piece (14) to the bottom of the reservoir (not illustrated). A circumferential barb (16) helps retain the dip tube (15) on the tail piece (14).

In the sidewall of the valve housing (4) there is another narrow orifice known as a vapour phase tap (VPT) (17). The VPT (17) is a conduit between the valve chamber (8) and the reservoir volume external to the valve chamber (8). When the dispenser is in use, this reservoir volume is filled by a propellant sitting above a liquid base composition located towards the bottom of the reservoir.

The axial positioning of the VPT (17) is such that it is above the narrowed lower section of the vale stem (5N) at all extents of valve stem (5) depression. I.e., the narrowed lower section of the valve stem (5N) is never moved to a position in which it is level with or above the VTP (17) during depression of the valve stem (5).

Figure 4 further illustrates the valve stem (5) component. As mentioned above, at the top of the valve stem (5), there is a valve stem pipe (5P) surrounding the valve stem central channel (5CC). Below this, there is a wider section (5W) of diameter such that it extends to relatively close to the inner surface of the valve housing (4). This is particularly true of multiple vertical splines (18) that protrude from the outer surface of wider section (5W) of the valve stem (5). These vertical splines (18) aid mixing within the valve chamber (8) by promoting vertical movement of the propellant entering the valve chamber (8) via the VTP (17), rather than just radial movement.

Figure 5 is a cross-sectional view of the wider section (5W) of the valve stem (5) and the surrounding valve housing (4). Also illustrated is the VTP (17) in the side wall of the valve housing (4). This is radially aligned to be between the vertical splines (18) protruding from the outer surface of the valve stem wider section (5W). This optimises the flow of propellant into the valve chamber (8) and its mixing with the liquid base composition, thus enhancing spray quality.

Claims

1. A spray product comprising (i) a liquid base composition; (ii) a propellant; and (iii) a dispenser to mix components (i) and (ii) into an aerosol on exit from said dispenser (iii); the propellant (ii) comprising a liquified gas propellant and a compressed gas; and the dispenser (iii) comprising:

• a reservoir for components (i) and (ii);

• a valve comprising a valve housing comprising a vapour phase tap (VPT) and a restricted tail piece (RTP), the valve housing containing a valve stem and a valve spring located around a narrowed lower section of the valve stem;

• a valve chamber exterior to the valve stem and within the valve housing;

• a means to transfer the liquid base composition to the valve housing via the RTP;

• a stem orifice between a valve stem central channel and the valve chamber;

• an actuator button associated with the valve stem, pressure upon which moves the valve stem and opens the valve by unblocking the stem orifice; wherein, opening of the valve allows entry into the valve chamber of liquid composition via the RTP and propellant via the VPT; and wherein opening the valve entails the valve stem being lowered; the narrowed lower section of the valve stem being below the VTP in the valve housing when the valve stem is fully depressed.

2. A spray product according to claim 1, wherein the liquid base composition is a cosmetic composition which is suitable for topical application onto the surface of the human body.

3. A spray product according to claim 1 or claim 2, wherein the liquid base composition is a suspension of particulate solid in a liquid.

4. A spray product according to any one of the preceding claims, wherein the valve housing, containing the valve stem and the valve spring, and the stem gasket are crimped onto a valve cup, which is in turn crimped onto an opening in the reservoir, together with a cup gasket, the stem gasket and the cup gasket providing a gas-tight seal between the associated components.

5. A spray product according to any one of the preceding claims, wherein the VPT is of diameter from 0.2 to 0.6 mm.

6. A spray product according to any one of the preceding claims, wherein the RTP is of diameter from 0.4 to 0.7 mm.

7. A spray product according to any one of the preceding claims, wherein the stem orifice has a diameter of from 0.2 to 0.6 mm.

8. A spray product according to any one of the preceding claims, wherein the ratio of the VPT diameter to the RTP diameter is from 1: 2 to 1: 1.

9. A spray product according to any one of the preceding claims, wherein the valve stem comprises one of more vertical splines protruding radially from the outer surface of the valve stem at a position above the narrowed lower section of said valve stem.

10. A spray product according to any one of claim 1 to 9, wherein vertical splines extend radially inwards from the inner surface of the valve housing at a position above the narrowed lower section of said valve stem.

11. A spray product according to claim 9 or claim 10, wherein the VPT is radially aligned to penetrate the valve housing between the vertical splines.

12. A spray product according to any one of the preceding claims, wherein the valve spring is never fully compressed, even when the valve stem has been depressed to its maximum extent.

13. A spray product according to any one of the preceding claims, wherein the VPT and stem orifice are radially out of alignment, preferably to an extent of from 30 to 180°.

14. A method of producing an aerosol from a liquid base composition and a propellant comprising liquified gas propellant and a compressed gas, wherein the method uses a dispenser comprising the dispenser features disclosed in any one of claims 1 to 13; wherein, opening of the valve allows entry into the valve chamber of liquid base composition via the RTP and propellant from a headspace above the liquid base composition via the VPT; and wherein opening the valve entails the narrowed part of valve stem and the surrounding spring being moved to position not below the VTP in the valve housing.

15. A method according to claim 13 or claim 14, wherein the liquid base composition is a suspension of particulate solid in a liquid.