MXPA01000010A - Inhalation of aerosol actives - Google Patents

Abstract

A method of reducing the inhalation of airborne/respirable particles or droplets having a diameter of less than 10 micrometres, produced by spraying liquid droplets from a spray device, which method comprises imparting a unipolar charge to the liquid droplets by double layer charging during the spraying of the droplets from a spray device, the unipolar charge being at a level such that the droplets have a charge to mass ratio of at least +/- 1 x 10-4 C/kg, whereby at least 10%by volume of the airborne respirable particles or droplets having a diameter of less than 10 micrometres in the vicinity of the mouth, nose or upper respiratory tract do not enter the lungs.

Description

INHALATION OF ACTIVE AEROSOL-TYPE SUBSTANCES The present invention relates to a method for reducing inhalation of sprayed compositions in the atmosphere, particularly compositions sprayed from an aerosol spray device. Spray aerosol compositions produce potential health / breathing hazards through the inhalation of particles or small sprayed drops. It is known that, for example, particles known as PM10 (defined herein as particles with a particle size less than 10 microns) can travel deep into the respiratory tract. A typical aerosol spray device produces small droplets of liquid with a range of small droplet diameters, but usually a proportion of the small droplets has a small drop diameter of less than 10 micrometers. We have now developed a method through which the inhalation of aerosol compositions can be reduced. In accordance with the present invention, there is provided a method for reducing inhalation of airborne / breathable particles or small airborne / breathable droplets having a diameter of less than 10 micrometers, produced by the spraying of small droplets of water. liquid from a spraying device, said method comprises the supply of a unipolar charge to the small droplets of liquide by double layer loading during the spraying of the small drops from a spraying device, the unipolar charge is at a level such that the small droplets have a charge to mass ratio of at least +/- 1 x 10"4 C / kg, so at least 10% by volume of respirable particles or small drops carried in air that have a diameter of less than 10 micrometers in the vicinity of the mouth, nose or upper respiratory tract do not enter the lungs, it is preferred that the unipolar Small drops of liquid are generated only by the interaction between the liquid within the spray device and the spray device itself as the liquid is sprayed therefrom. Particularly, it is preferred that the shape with which a unipolar load is provided to the small droplets of liquid is not even partially based on the connection of the spraying device to any external device that induces the load, such as for example an external source of relatively high voltage, or an internal device that induces charging, such as a battery. With this arrangement, the spray device is totally autonomous making it suitable for use in industrial, institutional and domestic situations. Preferably, the spraying device is a domestic pressure spraying device that has no electrical circuit but can be manually operated. Typically, said device has a capacity within a range of ID ml to 2000 ml and can be manually operated, or b: .en through an automatic drive mechanism. A particularly preferred household device is a manual aerosol can. Preferably, therefore, the charge to mass ratio of +/- 1 x 10 ~ 4 C / kg is given to the small droplets of liquid resulting from 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 dip tube, the characteristics of the valve and the formulation of the composition contained within the aerosol spray device being selected in such a way that This relationship between charge and mass of small droplets is achieved by means of double layer loading by providing the unipolar charge to the small droplets during the actual spraying of the small droplets of liquid from the orifice of the aerosol spray device. As a result of the method of the present invention, the small droplets of liquid forming the aerosol spray produced by the spray device carry an electrostatic charge. Small charged droplets will try to disperse as a result of mutual rejection and will preferably move to surfaces that have an opposite charge or a neutral charge, such as the face, nose, or upper respiratory tract, instead of penetrating the lungs of humans or animals in the vicinity of the aerosol spray. The greater the load on the small droplets of liquid forming the spray, the more easily they will be deposited in the nose, mouth or upper respiratory tract. The flow rate of the liquid product supplied from the spraying device will also have an effect on the quantity deposited at lower flow rates by encouraging a greater deposit than the higher flow rates. The method of the present invention has application in relation to all or most of the aerosol spray devices currently in use, examples are sprays for paint application, anti-sweat agents, hair sprays, insecticides, products for the horticulture, agents to freshen the air, waxes and polishing agents, oven cleaners, starches and finishes for cloth, shoes and leather care products, glass cleaners as well as various other products for home use, in institutions, in offices and in industrial areas. The method of the present invention prevents at least 10%, preferably at least 25%, more preferably at least 40%, preferably even more at least 75% by volume and especially at least 85% by volume of airborne particles having a size smaller than 10 micrometers that penetrate into the lungs. The particles carried in the air may comprise either the small liquid droplets per se, or b in may comprise particles produced as the small droplets break or evaporate after spraying. In general, the liquid composition sprayed into the air using the spray device is a mixture of water and hydrocarbon, or emulsion, or a liquid converted to an emulsion by agitation of the spray device before use, or during the spray process. While it is known that all liquid aerosols carry a negative charge or a net positive charge as a result of a double-layer charge, or due to the fragmentation of the small liquid droplets, the charge provided to the small droplets of the liquid sprayed Starting from standard devices is only in the order of +/- 1 x 10 ~ 8 to 1 x 10 ~ 5 C / kg. This invention is based on the combination of various design features of an aerosol spray system in order to increase the liquid loading during spraying 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 sprayed. A 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 including 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. Such 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 sprayed liquid 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 for the purpose of increasing 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 load levels in the liquid sprayed from the container. A narrow dip tube, for example approximately 1.27 mm in 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 sprayed from the aerosol device than a water alone formulation or a formulation of hydrocarbon only. It is preferred that a liquid composition for use in the present invention contain an oil phase, an aqueous phase, a surfactant and an impellent. Preferably, the oil phase includes a C9 C12 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. The small? Photo of liquid sprayed from the atomizing device. Spray 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, fumed silica, or a predetermined amount of a volatile material such as, for example, menthol or naphthalene. 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 lateral 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; Figure 6 illustrates the results obtained in Example 2; and Figure 7 illustrates the results obtained in the Example. With reference to Figures 1 and 2, an aerosol atomizing device according to the present invention is shown. Said device comprises a can 1, formed of a lacquered or unlacquered tin or aluminum plate or the like 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 tube end 7 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 18 is manually depressed, it pushes the valve rod 14 downwards against the action of the spring 15 as shown in Fig. 2 in such a way that the seal ring 24 already it does not close the side opening 17. In this 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 head sprayed 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 bore 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 flowing to the tank. through 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 valve stem bore 16 with the tailpiece bore 12 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 immersion 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, a cross-section through the drive device insert of the apparatus of Figures 1 and 2 is shown on an enlarged scale. For simplicity, the perforation 23 is shown in the form of a single cylindrical aperture. 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 driving device insert and the liquid running 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 would allow only low fluid flow rates. Thus, for example, it is pose to employ driving device insert drilling configurations (i) wherein the drilling outlet 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 exit is generally in the form of a cross; (v) where the openings together define an outlet in the form of concentric rings; and combinations of these configurations. Particularly preferred are drive device insert drilling configurations wherein a tongue-like portion protrudes into the liquid flow stream and can be vibrated in this manner. 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 pose configuration of a swirl chamber 35 of the drive device insert 22 is shown. The swirl chamber includes 4 side channels 36 equally spaced and tangential relative to an 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 towards 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 A formulation for air freshening was produced in the following manner :. 83% by weight of an isoparaffin solvent was introduced into a mixing vessel and stirred. 0.2% by weight of butylhydroxytoluene was added to the vessel as a corrosion inhibitor and stirring continued until a homogeneous mixture was obtained. Then, in turn, 5% by weight of polyglycerol oleate emulsifier and 11.8% by weight of a fragrance component were added and then applied continuously until a homogeneous mixture was obtained.

The mixture constituted the oil phase of the final product. 6% by weight of this oil phase was caused in a tin-coated aerosol can of the type described with reference to Figures 1 and 2, having a spray head drilling configuration as shown in Figure 4 and a Spray head swirl camera configuration as shown in Figure 5. The drive insert was formed of acetal resin. The lateral opening 17 of the valve stem had the form of 2 openings of 0.51 mm, the hole of taking of the vapor phase 27 had a diameter of 0.76 mm, the hole of the tail pipe 11 had a diameter of 0.64 mm and the diameter of immersion tube 4 was 3 mm. 59% by weight of the soft water was then added to the can and subsequently the valve assembly was adjusted on the can. 35% by weight of butane in the can was introduced through the valve assembly to achieve a pressure of 28,124 kg / m2 (40 psi). When pressing the drive device 18, a fine spray of small droplets of liguid with a value between race and mass of -1 x 10 ~ 4 C / kg and a flow rate of approximately 2.5 g / sec was obtained. The small drops quickly dispersed in the air. The aerosol spray device described above was compared to an aerosol spray device known as a standard, loaded with the same agent formulation to cool the air. It was found, by the same amount of spray, the amount of small drops of inhaled fluid was significantly lower with the device up compared to the known standard device. EXAMPLE 2 A model head with a conductive surface and oral orifice tube was placed in a cabinet (2mJ) and connected to ground. Pieces of filter paper (grade 4) of a size of 1.5 cm2 were fixed on the face on the left side of the nose, the right eye and the right side of the mouth. In each test, 7 g +/- 0.35 g of aerosol product was introduced into the cabin by means of a 3-second spray. The aerosol was introduced into the cabin from a position 1.4 m behind and 0.25 m above the head of the model. The product used in these tests had the composition provided below: Ingredient% weight / weight Bioallethrin 0.241 Bioresmethrin 0.046 Butylated hydroxytoluene 0.005 Deionized water 51.15 Fluorescein 0.05 H55 (propane / butane mixture 26% w / w (Boral)) 40,000 Norpar 13 (Exxon ) 7.500 Perfume 0.100 Polyglycerol Oleate 0.900 After spraying, the cabinet was left for 10 minutes and the filter paper was removed. Fluorescein is not very soluble in water, and therefore a phosphate buffer (pH 7, 0.1 M Na2HPO + NaH2P04H20) was used to extract the fluorescein from the filter paper. 5 ml of buffer was added to the paper and left for 24 hours. The paper was then removed and the sample was tested in a fluorimeter. The fluorimeter was set to zero reading when the buffer was only present in the cuvette. Known concentrations of product were made in phosphate buffer for use as calibration samples. The product was sprayed in a bottle and 40 mg was taken. Ten ml of buffer was added, and 5 ml of this was removed and placed in another flask and 5 ml of buffer was added to obtain a second concentration of 20 mg / 10 ml. Additional dilutions were carried out in the same way in such a way that concentrations of 10, 5, 2.5, 1.25 and 0.625 gm / 10 ml were obtained. These known concentrations and their fluorescence readings were then used to find the regression line. The equation of the line was then used to determine the amount of product present in the sample tests after the fluorescence reading. This value was then divided by the amount of product sprayed in the test to obtain a value of the amount of product that comes into contact with the face per gram of sprayed product and thus eliminate any effect of a slightly variable length of the spray. A charged aerosol was produced artificially by applying -10 kV to the can, since the presence of fluorescein made it difficult to load the dew naturally. This produced an aerosol with a charge to mass ratio of -4 X 10 ~ 4 C / kg. This was compared to an unloaded spray of the same composition. As shown in figure 6, the uncharged sprays deposited an average of 0.115 mg of product / g sprayed (n = 12, s = 0.064) on the papers on the face. Charged sprinkles deposited 63% more product on the face compared to non-charged sprays. 0.305 mg product / g spray was collected (n = 12, s = 0.172). The difference is significant to P <; 0.05 (t = 3.59, 22df). EXAMPLE 3 Following the procedure described in Example 2 to 3, a second spray of the following composition was tested. Ingredient% weight / weight Isopar G 4.996 Butylated hydroxytoluene 0.013 Polyglycerol oleate 0.299 Perfume 0.702 Propane / butane mixture 58.94 Fluorescein 0.05 A charged aerosol was artificially produced by applying -10 kV to the can, which produced an aerosol with a ratio between load and mass of -2.4 X 10 ~ 4 C / kg. This was compared to an unloaded spray of the same composition. As shown in Figure 7, a non-loaded spray deposits an average of 0.099 mg of product / g spray (s = 0.032) on targets on the face. Charged sprinkles deposited 73.5% more product on the face compared to the uncharged sprinkles, 0.374 mg of product / g spray was collected (s = 0.09). The difference is significant P < 0.05 (t = 9.85, lOdf).

Claims (1)

1. CLAIMS A method to reduce the inhalation of airborne particles / droplets / respirables having a diameter of less than 10 micrometers, produced by small droplets of liquid sprayed from a spray device, said method comprises supplying a load unipolar to the small droplets of liquid per double layer charge during the spraying of the small droplets from a spraying device, the unipolar charge is at a level such that the small droplets have a ratio between charge and mass of so less +/- 1 x 10"4 C / kg, so at least 10% by volume of airborne respirable particles or small droplets having a diameter of less than 10 micrometers in the vicinity of the mouth, nose or upper respiratory tract does not enter the lungs A method according to claim 1 wherein at least 25% by volume of respirable particles or small drops carried in Air that have a diameter smaller than 10 micrometers in the vicinity of the mouth, nose or upper respiratory tract do not enter the lungs. A method according to claim 1 wherein at least 40% by volume of respirable airborne particles or droplets having a diameter of less than 10 microns in the vicinity of the mouth, nose or upper respiratory tract do not penetrate In the lungs. A method according to claim 1 wherein at least 75% by volume of breathable particles or small airborne droplets having a diameter of less than 10 microns in the vicinity of the mouth, nose or upper respiratory tract do not penetrate In the lungs. A method according to any of the preceding claims wherein the spray device is an aerosol spray device. A method according to any of the preceding claims wherein the spray device contains an emulsion. A method according to any of the preceding claims wherein the small liquid droplets have a size within a range of 5 to 100 micrometers. A method according to any of the preceding claims wherein the spraying device contains a composition comprising an oil phase, an aqueous phase, a surfactant and an impeller. A method according to claim 8 wherein the oil phase includes a hydrocarbon C.-Ci ?. A method according to claim 9 wherein the C9-C2 hydrocarbon is present in the composition in an amount of 2 to 10% w / w. A method according to any of claims 8 to 10 wherein the surfactant is glyceryl oleate or a polyglycerol oleate. A method according to any of claims 8 to 11 wherein the surfactant is present in the composition in an amount of 0.1 to 1.0% w / w. A method according to any of claims 8 to 12 wherein the impeller is liquefied petroleum gas. A method according to claim 13 wherein the impellent is present in the composition in an amount of 20 to 50% w / w. A method according to any of the preceding claims wherein the unipolar charge is provided to the small droplets of liquid only by the interaction between the liquid and the spraying device, without providing any load through an internal or external inductor device. load. A method according to claim 15 wherein the charge to mass ratio of at least +/- 1 X 10"4 C / kg is provided to the small droplets of liquid 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 dip tube, the characteristics of the valve and the formulation of the composition contained within the device aerosol spray being selected to achieve dec: there is a relationship between charge and mass of small droplets per double layer charge providing the unipolar charge to the small droplets during the actual spraying of the small drops of liquid from the orifice of the spray device of aerosol.