MXPA01000021A - Treatment of airborne microorganisms - Google Patents

Abstract

A method of disinfecting or sanitising a space occupied by airborne microorganisms and/or viruses, which method comprises directing into the space liquid droplets from a spray device containing a disinfecting or sanitising composition, a unipolar charge being imparted to the said liquid droplets by double layer charging during the spraying of the liquid droplets from the aerosol spray device, the unipolar charge being at a level such that the said droplets have a charge to mass ratio of at least +/- 1 x 10-4 C/kg.

Description

TREATMENT OF AIR COVERED MICROORGANISMS The present invention relates to the treatment of microorganisms and viruses carried in the air. Disinfectants and sanitary compositions based on essential oils are known, for example, from U.S. Patent No. 5403587. This patent relates to antimicrobial compositions for use in the disinfection and / or cleaning of hard surfaces such as countertops, mosaics, porcelain products, such as sinks, toilets, floors, windows, food additives, glassware, dishes as well as dental and surgical instruments. The compositions comprise: a) an anti-microbial effective amount of an essential oil capable of dissolving or dispersing in an aqueous vehicle and having antimicrobial properties when incorporated into an aqueous carrier; b) a solubilizing or dispersing amount of a sufficient solubilizing agent or dispersion to form an aqueous solution or dispersion of the essential oil in an aqueous vehicle; and c) a sufficient amount of water to reach 100% by weight. Essential oils established as useful in the invention in accordance with that disclosed in the North American Patent No. 5403587 include oils obtained from thyme, lemon verbena, lemon, orange, anise , clove of spice, roses, lavender, citronella, eucalyptus, mint, camphor, sandalwood and cedar. The compositions of the North American Patent No. 5403587 are established as being capable of being formulated with conventional impellers for dispersion as aerosols from conventional pressure vessels. The impellents which may be employed include isobutane, n-butane, propane, dimethyl ether and mixtures thereof, as well as chlorofluorohydrocarbons, fluorohydrocarbons and mixtures thereof. It is known that it is difficult to treat microorganisms carried in the air. In general, it is not easy to completely eliminate them from a particular space, such as the space defined by a room. In addition, any aggressive form of treatment, such as the use of a spray of a composition that is toxic to microorganisms, will probably represent a danger to the health of humans or animals within the treated space. Bacteria, viruses, and fungal spores can be considered as particles when they are carried in the air, especially since they are frequently fixed or frequently associated with dust particles. In the case of the use of an aerosol spray device, a liquid composition containing a disinfectant is sprayed in the form of small droplets in the space to be disinfected. However, a low collision rate between small droplets of liquid and microorganisms in the air results in ineffective destruction of microorganisms. The practical consequence of this inefficiency is that the disinfectant composition must be used in a large quantity, which causes a risk to health. There are other possible side effects which include, in the case of the use of a perfumed composition, a strong perfume resulting since it is required to employ a considerable amount of disinfectant composition and / or a limited selection of fragrances. An aerosol spray type device would be more effective if the small aerosol spray droplets had a higher collision rate with the microorganisms. We have now developed an improved method to disinfect a space or to render it sanitary. In accordance with the present invention there is offered a method for disinfecting or returning sanitary a space occupied by microorganisms and / or viruses carried in the air, said method comprises the directing in the space small drops of liquid from a spraying device that it contains a disinfectant or sanitary composition, a unipolar charge being provided to said small drops of liquid by double-layer loading during the spraying of the small drops of liquid from the spraying device, the unipolar charge being at a level such that said small droplets have a charge to mass ratio of at least +/- 1 x 10"5 C / kg The disinfectant or sanitary composition that is sprayed in the present method invention contains at least one antimicrobial agent Examples of such antimicrobial agents are essential oils such as thyme, lemon verbena, lemon, orange, grapefruit, yeast, oregano, anise, clove, cinnamaldehyde, cinnamon, carbacrol, roses, lavender, citronella, eucalyptus, peppermint, camphor, sandalwood, Siberian pine needle, Scots pine, tea, juniper, rosewood, patchouli, vetiver, cedar and mixtures thereof Other antimicrobial agents that may be employed in the present invention include bactericides , for example quaternary ammonium compounds such as for example alkyldimethylbenzylammonium saccharinate and benzalkonium chloride, or fungicides such as clotrimazole, miconazole nitrate, organoest compounds year, organic acids, halogenated phenols, quaternary ammonium compounds, 8-hydroxyquinoline, diamidines, organic mercury derivatives and parabens. It is preferred that the unipolar charge provided to the small drops of liquid be generated only by the interaction between the liquid within the atomization device and the atomization device itself as the liquid is sprayed therefrom. Particularly, it is preferred that the way how a unipolar load is provided to the small droplets of liquid is not even partially based on the connection of the device to an external load induction device such as, for example, a relatively high voltage source or well to an internal load-inducing device, such as a battery. With an arrangement of this type, the atomization device is completely autonomous and therefore suitable for use in industrial, institutional and domestic environments. Preferably, the atomization device is a domestic pressure atomization device that does not have an electric circuit and that could be handled manually. Typically, such a device has a capacity within a range of 10 ml to 2000 ml and can be operated manually or through an automatic drive mechanism. A particularly preferred household device is a manual aerosol can. Preferably, therefore, the ratio between the charge and the mass of the small droplet is at least +/- 1 x 10"4 C / kg and is provided to the small droplets as a result of the use of a spray device with at least one of the characteristics of the material of the actuator, size and shape of the orifice of the actuator, diameter of the immersion tube, the characteristics of the valve and the formulation of the disinfectant or sanitary composition contained within the aerosol atomization device being selected in such a way that this ratio between charge and mass of small droplet is achieved by means of a double layer charge that provides the unipolar charge to the small droplets during the spraying itself of the small drops of liquid from the orifice of the aerosol spray device As a consequence of the method of the present invention, microorganisms and / or viruses carried in the air can be eliminated with considerable efficiency compared to known spray methods. Particularly, a much smaller amount of sanitizing or disinfecting agent is required than in the case of the prior art. This result is achieved due to the unipolar load provided to the small drops of liquid from the aerosol spray. This load has two effects. Small individual droplets are attracted to microorganisms and / or viruses, including microorganisms fixed on dust particles. Since all the small drops carry the same charge of polarity, they repel each other. Therefore, there is little or no coalescence of the small droplets and, in contrast, such droplets tend to disperse to a large extent compared to the small drops without charge. In addition, if the forces of charge repulsion within the small droplets is greater than the surface tension force of the small droplets, the small droplets charged in several small charged droplets of smaller size (exceeding the Rayleigh limit) are fragmented. This process continues until the two forces equalize or until the small drop has completely evaporated. Microorganisms carried in the air, including microorganisms fixed on dust particles, are usually electrically isolated from their surroundings and typically are at a potential that is the same as the potential of their environment. In this situation, a microorganism isolated within a cloud of electrically charged small droplets of liquid will probably cause a distortion of the configuration of the electric field generated by the small droplets in such a way that the attraction of the small droplets towards the microorganism is improved. In fact, the microorganism is focused by a small drop of liquid. This improvement in the interaction between the small charged droplets and the microorganisms is due to the combined effect of the additional diffusion forces generated within the cloud of small droplets charged by the electric field, which causes a modification of the trajectory of each small drop in such a way that each small droplet g is directed towards a microorganism. In general, the liquid composition sprayed into the air by the use of the aerosol spray device is preferably a mixture of water and hydrocarbon, or an emulsion, or a liquid which is converted into an emulsion by stirring the device. atomization before use, or during the spraying process. While it is known that all liquid aerosols carry a negative or positive net charge as a result of double layer loading or the fragmentation of small liquid drops, the charge provided to the small drops of liquid sprayed from standard devices is only order of +/- 1 x 10"9 to 10 ~ 5 C / kg The invention is based on the combination of several characteristics of the design of an aerosol spray device in order to increase the load of the liquid as it is sprayed at from the aerosol spray device A typical aerosol spray device comprises: 1. An aerosol can containing the composition to be sprayed from the device and a liquid or gaseous impeller; 2. A dip tube that extends into the can, the top end of the dip tube is connected to a valve; 3. A drive device placed above the valve that can be depressed for the purpose of operating the valve; 4. An insert provided in the drive device comprising an orifice from which the composition is roela. The preferred aerosol spray device for use in the present invention is described in WO 97/12227. It is possible to provide higher loads to the small droplets of liquid by choosing aspects of the aerosol device that includes the material, shape and dimensions of the drive device, the drive device insert, the valve and the dip tube and the characteristics of the liquid to be sprayed in such a way that the required level of charge is generated as the liquid is dispersed in the form of small drops. Several characteristics of the aerosol system increase the double-layer loading and the exchange of charge between the liquid formulation and the surfaces of the aerosol system. These increases are caused by factors that can increase the turbulence of the flow through the system, and increase the frequency and speed of contact between the liquid and the internal surfaces of the container and valve and drive system.

By way of example, characteristics of the drive device can be optimized in order to increase the load levels in the liquid sprayed from the container. A small hole in the drive device insert, of a size of 0.45 mm or less, increases the charge levels of the sprayed liquid through the drive device. The choice of material for the drive device can also increase the load levels in the sprayed liquid from the device with material, for example nylon, polyester, acetal, PVC and polypropylene tending to increase the load levels. The geometry of the hole in the insert can be optimized in order to increase the load levels in the liquid as it is sprayed through the drive device. Inserts that promote mechanical rupture of the liquid offer a better load. The drive device insert of the atomization device can be formed from a conducting material, semiconductor insulator or static-dissipater. The characteristics of the immersion tube can be optimized in order to increase the levels in the liquid sprayed from the container. A narrow immersion tube, for example of approximately 1.27 mm internal diameter, increases the charge levels in the liquid, and the material of the dip tube can also be changed in order to increase the load. The characteristics of the valve can be selected in order to increase the ratio between load and mass of the liquid product as it is sprayed from the container. A small tailpiece hole in the cover, approximately 0.65 mm, increases the ratio between the load and the mass of the product during spraying. A small number of holes in the rod, for example 2 x 0.50 mm, also increases the load of the product during spraying. The presence of a vapor phase tap helps to optimize the charge levels, a large orifice vapor phase tap, for example from about 0.50 mm to 1.0 mm generally provides higher levels of charge. Changes in product formulation can also affect load levels. A formulation containing a mixture of hydrocarbon and water, or an emulsion of a non-miscible hydrocarbon and water, will provide a higher charge to mass ratio when relieved from the aerosol device than a water alone formulation or a formulation of hydrocarbon only. It is preferred that the microorganism treatment composition for use in the present invention comprises an oil phase, an aqueous phase, a surfactant, an antibacterial or antiviral agent and an impellent. Preferably, the oil phase includes a C 9 C 2 hydrocarbon preferably present in the composition in an amount of 2 to 10% w / w. Preferably, the surfactant is glyceride oleate or a polyglycerol oleate, preferably present in the composition in an amount of 0.1 to 1.0% w / w. Preferably, the impeller is liquefied petroleum gas (LPG) which is preferably butane, optionally in admixture with propane. The impeller may be present in an amount of 10 to 90% w / w depending on whether the composition is contemplated for spraying in the form of a "wet" composition or in the form of a "dry" composition. In the case of a "wet" composition, the impeller is preferably present in an amount of 20 to 50% w / w, preferably in an amount of 30 to 40% w / w. Small droplets of liquid sprayed from the aerosol spray device will generally have diameters within a range of 5 to 100 micrometers, with a peak of small droplets of approximately 40 micrometers. The liquid that is sprayed from the aerosol spray device may contain a predetermined amount of a particulate material, for example, smoked silica, or a predetermined amount of a volatile material such as, for example, menthol or naphthalene.

The method of the present invention, in addition to killing microorganisms, also accelerates the natural process of precipitation of particles carried in the air by indirectly charging the particles, thus enabling a rapid and convenient improvement of the air quality. A can for a typical aerosol spray device is formed of aluminum or of a lacquered or unlacquered tin plate or the like. The drive device insert can be formed, for example, of acetal resin. The side opening of the valve stem can typically be in the form of two openings of diameters of 0.51 mm. The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic cross section through an aerosol spray apparatus in accordance with the present invention; Figure 2 is a diagrammatic cross section through the valve assembly of the apparatus of Figure 1; Figure 3 is a cross-section through the drive device insert of the assembly illustrated in Figure 2; Figure 4 shows the configuration of the orifice of the spray head shown in Figure 3 when viewed in the direction A; and Figure 5 shows the configuration of the swirl chamber of the spray head shown in Figure 3 when viewed in the direction B. With reference to Figures 1 and 2, there is shown an aerosol spray device of according to the present invention. Said device comprises a can 1, formed of an aluminum or tin plate lacquered or unlacquered or similar in a conventional manner, which defines a reservoir 2 for a liquid 3 having a conductivity such that the small drops of the liquid can carry a proper electrostatic charge. Also within the can is a gas under pressure which is capable of pushing the liquid 3 out of the can 1 through a duct system comprising a dip tube 4 and a valve and a drive device assembly 5. The dip tube 4 includes an end 6 terminating in a peripheral part of the can bottom 1 and another end 7 connected to the tail part 8 of the valve assembly. The tailpiece 8 is fixed through a mounting assembly 9 installed in an opening in the upper part of the can and includes a lower portion 10 defining a tailpiece orifice 11 where the end 7 of the tube is connected. 4. The tailpiece includes a perforation 12 of a relatively narrow diameter in a lower portion 11 and a relatively wider diameter in its upper portion 13. The valve assembly also includes a rod tube 14 mounted within the bore. 12 of the tailpiece and positioned to be axially displaced within the bore 12 due to the action of the spring 15. The valve rod 14 includes an internal bore 16 having one or more side openings (bore holes) 17 ( see Figure 2). The valve assembly includes a drive device 18 having a central bore 19 which houses the valve rod 14 in such a manner that the bore 16 of the rod tube 14 is in communication with the bore 19 of the drive device. A passage 20 in the drive device extending perpendicularly relative to the bore 19 joins the bore 19 with a recess including a post 21 in which a spray head is mounted in the form of an insert 22 including a bore 23 in communication with the passage 20. A ring 24 of elastomeric material is provided between the external surface of the valve stem 14 and, usually, this seal ring closes the side opening 17 in the valve stem 14. The construction of the valve assembly is such that when the actuating device 13 is manually depressed, it pushes the valve rod 14 downwardly against the action of the spring 15 as shown in Fig. 2 in such a way that the seal ring 24 already does not close the side opening 17. In this In position, a path is provided from the reservoir 2 to the perforation 23 of the spray head in such a way that the liquid can be pushed, under the pressure of the gas in the can, towards the spray head through a duct system comprising the dip tube 4, the tailpiece bore 12, the valve stem bore 16, the drive device bore 19 and the passage 20. A hole 27 (not shown in Figure 1) is provided in the wall of the glue piece 8 and constitutes a vapor phase socket whereby the gas pressure in the tank 2 can act directly on the liquid that flows through of the valve assembly. This increases the turbulence of the liquid. It has been found that an increased load is provided if the diameter of the hole 27 is at least 0.76 mm. Preferably, the lateral opening 17 joining the perforation 16 of valve stem with perforation 12 of tailpiece has the shape of two holes, each with a diameter not greater than 0.51 mm in order to increase the generation of electrostatic charge. In addition, the diameter of the dip tube 4 is preferably as small as possible, for example 1.2 mm, in order to increase the load provided to the liquid. Also, the charge generation is increased if the diameter of the tailpiece hole 11 is as small as possible, for example, no more than about 0.64 mm. Referring now to Figure 3, an enlarged scale is shown, a cross section through the drive device insert of the apparatus of Figures 1 and 2. For simplicity, the perforation 23 is shown in the form of a single cylindrical opening in this Figure. However, the perforation 23 preferably has, for example, the configuration illustrated in Figure 4. The apertures in the perforation 23 are indicated by the reference number 31 and the portions defining the apertures in the perforation are indicated through of the reference number 30. The total peripheral length of the portions defining the openings in the perforation outlet is indicated by L (in mm) and a is the total area of the opening in the perforation outlet (in mm2) and the values of L and a are indicated in the Figure 4. L / a is greater than 8 and this condition is especially suitable for load development since it means an increased contact area between the drive device insert and the liquid passing through it. Many different configurations can be adopted in order to produce a high L / a ratio without reducing the cross-sectional area to a value that will allow only low fluid flow rates. So, for example, it's l > it is possible to employ driving device insert piercing configurations (i) wherein the piercing outlet 5 comprises a plurality of segment-type openings (with or without a central opening); (ii) where the outlet comprises several openings of the sector type; (iii) where the openings together form an outlet in the form of a grill or grid; (iv) where the output is generally in the form of cross; (v) where the openings together define an outlet in the form of concentric rings; and combinations' of these configurations. Driven insertion drilling configurations are particularly preferred wherein a tongue-like portion protrudes into the stream of liquid flow and can be vibrated in this way. This property of vibration can cause a turbulent flow and improve the separation of electrostatic charge from the double layer, allowing a greater load to move in the volume of the liquid. Referring now to Figure 5, a plan view of a possible configuration of a swirl chamber 35 of the drive device insert 22 is shown. The swirl chamber includes 4 lateral channels 36 equally spaced and tangential to one another. area central 37 surrounding the perforation 23. In use, the liquid pushed from the reservoir 2 by the gas under pressure travels along the passage 20 and hits the channels 36 in a normal manner with respect to the longitudinal axis of the channels. The positioning of the channels is such that the liquid tends to follow a circular motion before entering the central area 37 and thence to the perforation 23. As a consequence, the liquid is subjected to a substantial turbulence that increases the electrostatic charge in the liquid. The following examples illustrate the invention. EXAMPLE 1 An aerosol disinfectant composition was prepared from the following components:% weight / weight Ethanol 54 Silicone surfactant 0.1 Antibacterial agent selected 0.8 among those listed below Water 17.2 Liquid petroleum gas 28 The composition was introduced into a can tin plate aerosol with valve assemblies comprising a polyethylene immersion tube 4 of 3 mm, a hole 11 of tailpiece of 0.64 mm, a socket 27 of vapcr phase of 0.64 mm, and 4 x 0.61 mm lateral openings of valve stem. The drive device 18 was a type Cosmos equipped with an insert 22 of drive device 0.51 / 0.66 mm Aqua (both supplied by Precision Valve). The antibacterial agent can be any suitable material. By way of example, an essential oil may be used, including one or more of the following: lemon verbena, lemon, orange, yeast, spice clove, thyme, oregano, cinnamaldehyde, cinnamon and / or carvacrol. A preferred amount of the antibacterial agent in the composition is from 0.2 to 0.25% w / w. The level of charge of the small droplets expelled from this can was artificially raised to a load to mass ratio of approximately -1 x 10 ~ 4 C / kg by applying a 10 kv load to the can seam from a high voltage power source. By pressing the drive device 18, a thin layer of small droplets of liquid having a charge to mass ratio of -1 x 10 ~ 4 C / kg and a flow rate of about 1.2 g / sec was obtained. The small drops quickly dispersed in the air. The aerosol spray device described above was compared to a known standard aerosol spray device loaded with the same aerosol formulation. The protocol that we mentioned below was followed. A suspension of Micrococcus luteus containing approximately 109 colony forming units / ml in water is prepared. HEPA filtered air is supplied to an environmental test chamber with a volume of 28 cubic meters. The bacterial suspension is applied to the test chamber with an atomizer for 60 seconds and is distributed around the chamber for an additional 60 seconds with a re-circulation fan. An agar slit sampler is activated for 2 hours, obtaining samples after 1, 15, 30, 60 and 120 minutes. The slit plates are collected on agar. The plates are tested, incubated and the colonies are counted in order to offer the control results (which are the average of 3 experiments). The above procedure is repeated 3 times, however, before activating the agar slit sampler, the electrostatically charged test product is sprayed into the test chamber for 10 seconds. This is repeated again three times with the conventional non-loaded test product. The results obtained from the roclo products loaded and not loaded are compared (after taking into account the control results) and it is demonstrated in this way that there is a significant increase in the antibacterial performance with the electrostatic product. EXAMPLE 2 The test organism Micrococcus lutens (ATCC NCTC) obtained from culture was used as a final suspension containing approximately 109 colony forming units / ml in water. The test chamber had a volume of 28 m3 with filtered HEPA air supply and extracted air. The equipment in the chamber was controlled remotely from a control room. Bacteria were sprayed from a collision atomizer for 60 seconds and mixed with the ambient air for an additional 60 seconds by the use of a fan. Five totally glass impact detectors (AGÍ) were activated in the following times: 1, 4, 29, 59 and 119 minutes after the release of the bacteria. Each impact detector collected air from the test chamber for one minute. After the first impact detector has finished its sampling, a spray-dried test disinfectant was released into the chamber from an aerosol can. The test formulation was as follows: Component% weight / weight Butane 40 35 Sorbitan mono-oleate 1 Luisa herb oil 7 Sodium nitrite 0.12 Triethylene glycol 2.5 Soft water 54.38 The spray was released for 10 seconds. The performance of the uncharged aerosol composition was compared to the same aerosol composition with load applied artificially to the can. The voltage applied to the can was -3kV, thus achieving an aerosol with a load to mass ratio of -1.3 x 10 ~ 4 C / kg. The effect of applying the charge to the aerosol on the concentration of microorganisms carried in the air was recorded by the following AGI. The number of bacteria collected in the AGI was evaluated by removing 0.1 ml of liquid from the AGI and by placing it on an agar plate, this was replicated once. The plates were then incubated at a temperature of 30 ° C for 72 hours. The colonies were counted and the average of the two plates appears in the results given below: Results Table 1: Number of Micrococcus lutens collected in the impact detector. Applied load AGÍ 1 AGÍ 2 AGÍ 3 Aerosol 1 minute 14 minutes 29 minutes No 3225 70 5 Si 3533 20 0.8 Applied load AGÍ 4 AGÍ 5 To aerosol 59 minutes 119 minutes No 0.8 0 Yes 0.8 0 15 20

Claims (15)

1. CLAIMS 1.
2. A method to disinfect or return sanitary a space occupied by microorganisms and / or viruses carried in the air, said method comprises the fact of directing to the space small droplets of liquid from a device of atomization containing a disinfectant composition or sanitary, a unipolar charge being provided to said small droplets of liquid by a double layer charge during the spraying of the small drops of liquid from an aerosol atomizing device, the unipolar charge is at a level such that said small droplets they have a charge to mass ratio of at least +/- 1 x 10"4 C / kg 2.
3. A method according to claim 1, wherein the atomization device is an aerosol atomizing device. method according to claim 1 or according to claim 2, wherein the disinfectant or sanitary composition is an emulsion.
4. 4. A method according to any of the preceding claims, wherein the small droplets of liquid have a diameter within a range of about 5 to 100 microns.
5. 5. A method according to any of the preceding claims, wherein the unipolar charge is provided to the small drops of liquid only • by the interaction between the liquid and the atomization device, without providing any load from an internal or external load induction device.
6. 6. A method according to claim 5, wherein the ratio between the load and the mass of the small • Drops of at least +/- 1 x 10 ~ 4 C / kg are provided to 10 the small droplets as a result of the use of an aerosol spray device with at least one of the characteristics of the material of the drive device, the size and shape of the orifice of the drive device, the diameter of the tube of 15 dipping, the characteristics of the valve and the formulation of the disinfectant or sanitary composition contained within the aerosol spray device being selected in order to achieve said ratio between load and mass of the small drop by 20 a double layer charge that provides the unipolar charge to the small droplets during the actual spraying of the small drops of liquid from the orifice of the aerosol atomization device.
7. 7. A method according to any of the preceding claims, wherein the disinfectant or sanitary composition comprises an oil phase, an aqueous phase, a surfactant, an agent • antibacterial, a fungicide or an antiviral agent, and an impellent.
8. 8. A method according to claim 7, wherein the antibacterial or antiviral agent is an essential oil selected from thyme, lemon verbena, lemon, orange, grapefruit, yeast, oregano, anise, clove • spice, cinnamaldehyde, cinnamon, carbacrol, rose, 10 lavender, citronella, eucalyptus, peppermint, camphor, sandalwood, juniper, Siberian pine needle, Scots pine, tea, rosewood, patchouli, vetiver, cedar and mixtures of same.
9. 9. A method according to claim 7, wherein the antibacterial agent is a quaternary ammonium compound.
10. 10. A method according to any of claims 7 to 9, wherein the oil phase includes a C9-C2 hydrocarbon.
11. 11. A method according to claim 10 wherein the C9-Ci2 hydrocarbon is present in the composition in an amount of 2 to 10% w / w.
12. 12. A method according to any of claims 7 to 11, wherein the surfactant is oleate 25 of glyceryl or a polyglycerol oleate.
13. 13. A method according to any of claims 7 to 12, wherein the surfactant is • found in the composition in an amount of 0.1 to 1.0% weight / weight.
14. 14. A method according to any of claims 7 to 13, wherein the impeller is liquefied petroleum gas.
15. 15. A method according to claim 14, wherein • the impellent is present in the composition in an amount of 20 to 50% w / w. fifteen twenty 25