EP0569590B1

EP0569590B1 - Method for creation of positive pressure of sorbed gas in an aerosol package

Info

Publication number: EP0569590B1
Application number: EP92915519A
Authority: EP
Inventors: Anatoly Yakovlevich Stolyarevski; Aleksandr Sergeevich Doronin
Original assignee: INTERNATIONAL CENTER OF SCIENTIFIC CULTURE WORLD
Current assignee: INTERNATIONAL CENTER OF SCIENTIFIC CULTURE WORLD
Priority date: 1991-06-29
Filing date: 1992-06-26
Publication date: 2000-03-01
Anticipated expiration: 2012-06-26
Also published as: WO1993000277A1; EP0569590A4; DE69230723T2; ATE190031T1; RU2016820C1; DE69230723D1; EP0569590A1

Abstract

The invention relates to packaging techniques, namely to methods of creation of positive pressure for discharging the content of a package and is directed to providing for uniform flow rate of the atomized substance, increasing the efficiency, as well as decreasing the adverse effect on the environment of the use of the aerosol packages. An aerosol package, in the working cavity of which a positive pressure of a sorbed gas is created when it is used, comprises a sealed receptacle (1) filled with a substance (liquid) (9) to be atomized and provided with a gas cushion containing a sorbed gas, for instance CO2. The receptacle is connected to the atomizing nozzle (5) through a tube (13) whose input is located below the level of the substance (9) to be atomized. The package also comprises a sorbent (11) contained in a cavity (10) isolated from the outside atmosphere outside the receptacle (1) and from the substance (9) to be atomized, whereas the cavity (10) is connected hydraulically to the gas cushion. As sorbent is used a substance which has a higher absorption capacity for the sorbed gas than the substance (9) to be atomized, for instance the activated carbon or zeolite. The method allows to decrease the adverse effect of the human activity on the environment. <IMAGE>

Description

Field of Art

The invention relates to packaging techniques and can be used, for instance, in aerosol packages, purposed for applying paint and varnish coatings, in medicine, mainly for breast diseases prophylaxis and treatment and local anaesthesia, in perfumery, and also in housekeeping for spraying different household chemical substances etc.

Prior Art

One of the global problems is an increasing adverse effect of the human activity on the environment, and in particular, the deflection of the protective ozone layer under the influence of chlorine-containing substances, the usage of which was limited by the Montreal Protocol. Due to this reason, the alternative technical methods for creation of positive pressure within the package are being proposed in order to decrease or eliminate the hazardous effect on the environment.

In the art are known methods for creation of positive pressure for gaseous substances within the working cavity of aerosol package (European Patent Application EP - A - 385773, Int. Cl. F17C 11/00, 1990 and French Application No. 2 331 485, Int. Cl. B31/10, 1977).

European Patent Application EP - A - 385773 discloses a gas storage and dispensing system for the substantially reversible storage of a gas. Said gas storage and dispensing system comprising a polymeric material having molecular microvoids occupiable by the gas to cause the polymeric material to form a two-phase gas/solid reversible sorption gas storage system which will tend to sorb increasing quantities of gas in increasing ambient gas pressure, and tend to desorb previously sorbed gas with decreases in ambient gas pressure. Gas, which comprises carbon dioxide, can be used as propellant. Besides this, according to this document, a dispenser can comprise a semi-permeable barrier enclosing the gas storage and dispensing system, the semi-permeable barrier being permeable to propellant gas but substantially impermeable to the non-gaseous component or components of gas storage and dispensing system whereby the semi-permeable barrier passes the propellant gas to pressurise the product by direct contact while maintaining the non-gaseous component or components of the gas storage and dispensing system out of direct contact with the product. According to this document in variants, illustrated in fig. 1 -4 the opportunity of use of absorption capacity of the atomized liquid to provide decrease of the range of the change of initial and ultimate pressure in the sealed package is not provided. Decrease of this range provides in its turn the efficiency of quality of spraying in the proposed method.

Besides, as the mean of separation of sorbent and atomized substance an hydrophobic membrane 460 (p. 15, line 13-25) is used. This membrane does not prevent penetration of vapors of the atomized liquid through it in to the sorption system 30. Penetration of vapors of the atomized liquid through the membrane, particularly aromatie substances from the atomized deodorant liquid, will cause to rapid decrease of their quantity in the composition of the atomized liquid. This result to worsen consumer capacity (quality) of deodorant.

Besides, in the known method acetone is one of the elements in the composition of the sorption system 30. Vapors of acetone can penetrate through a hydrophobic membrane 460 so that to change the composition of the atomized subtance, worsening consumer capacity of the package.

French application No. 2331485 (Int. Cl. B65B31/10, 1977) discloses an aerosol package in which an atomized product is located in a first chamber of the aerosol package, a second chamber contains solid sorbent and propellant, the second chamber being provided with a changing valve and means for passing propellant to the first chamber.

However, the known aerosol package does not provide the following factors:

first, means for separating a sorbent from volatile substances and/or vapors contained in the atomized liquid. Particularly, gaseous aromatic agents of deodorants and medicines can penetrate through a hydrophobic membrane to the chamber with a sorbent and be sorbed. As the result, composition of the atomized liquid can change which is inadmissible from the point of providing useful properties of the aerosol package. The same requirement also refers to any valve means used to pass desorbed propellant from the second chamber to the first chamber.

second, means for providing a constant quantity of a sorbent in the second chamber. Failure to meet this requirement results in carrying away a portion of grains or activated carbon by a propellant to the first chamber during discharge of a propellant from the second chamber to the first chamber through valve means which causes unplanned desorption of the propellant from the sorbent, i.e. a pressure rise inside the aerosol package and deterioration of liquid spraying uniformity. Furthermore, tests proved that particles of solid sorbent, in flow, can block up valve means and this will violate the first requirement above. The conventional means for maintaining a constant quantity of the solid sorbent are as follows:

use of solid sorbent in a form of a firm monoblock;
location of grained sorbent in an additional gas-tight shell;
use of firm particles, the mean diameter thereof exceeding the diameter of an input orifice in the valve means;
mounting a gas-permeable filter at the input of valve means (said filter made, for example, of foam plastic, wire net, cloth, etc).

third, using as a sorbent of the atomized liquid having lower absorption properties with respect to propellant, than that of the solid sorbent, which provides for:

improvement of atomizing owing to dispersing a propellant when atomizing liquid saturated with the propellant;
increase of extent of filling the aerosol package with the liquid to be atomized without deterioration of spraying, owing to redistribution of the propellant between the chambers, and thereby reducing the second chamber volume with respective increase of the first chamber volume;
improvement of the aerosol package operation safety at various weather conditions in service (for example, from 0°C to 55°C), owing to reduction of the pressure inside the aerosol package at heating thereof (thermal shocks) due to sorption by liquid sorbent of the propellant overflown from the second chamber to the first one through the valve means, which complies with the two requirements above.

FR-A-2596139 (Int. Cl. F17C5/00, 1987) discloses a method for charging an aerosol package with a propellant, carbone dioxide. This technical solution, fails to provide a separation of a sorbent from the atomized liquid. Lack of such separation results in negative effects described above. Besides, in such package a valve can be blocked with sorbent particles which leads to failure of the package as a whole.

GB-A-1322 942 (Int. Cl. F17C11/00, 1973), discloses a variant of an aerosol package structure comprising separated liquid propellant and an atomized liquid, in which spraying is accomplished by injection. This method of spraying is less economical, because it requires extensive accommodation of propellant during usage of the package. Furthermore, the structure does not exclude interaction of the atomized substance with the ambient air inside the package, which is inadmissible in the aerosol packages used for varnishes and paints, medicines and cosmetics.

Known in the art is the device for expelling substances from pressurized containers (International Application PCT/EP90/0S842, publication WO 91/07620, Int.Cl. F17 C11/00, 1991).

The aforementioned application discloses an aerosol package structure comprising separated propellant source and atomized liquid. The propellant is hydrogen in a form of a hydride of an appropriate element, particularly, metal hydrides. Under the pressure drop in a container with atomized liquid, hydrogen escapes through a valve 5 to a cavity 4, maintaining pressure in a working space of the package. Metal hydrides are chemical compounds in which hydrogen molecules form a chemical compound with metal. Heat of metal hydride synthesis reactions is comparable with heat of chemical reactions (10 - 100 kilocalories per mole). Heat of physical adsorption is 1 - 5 kilocalories per mole for simple molecules. The aforementioned systems attain equilibrium at entirely different pressure and temperature values. Particularly, for typical metal hydrides MnNi₅ - H and FeTi - H indicated in the application as basic examples, dependence of equilibrium dissociation pressure on temperature causes either a prohibitive pressure (over 1.5 Mpa) from safety point (package destruction) at the maximum working temperature 55°C, as in the case of MnNi5 - H system, or insufficient pressure (below 0.3 Mpa) to provide atomizing at working temperature 20°C and below, as in the case of some FeTi - H systems.

At the same time, high values of dissociation energy of metal hydrides result in insufficient rates of hydrogen discharge (about 1% per min) which prevents to maintain working pressure when the package is being emptied.

The specification of the cited prior art fails to mention that the atomized liquid possesses absorption capacity.

Well known is a method of creation of positive pressure for gaseous carbone dioxide (CO2) within the working cavity of aerosol package DE-A-36 25561, (Int. Cl. B65D 88/14, 1988). The method comprises the desorption of CO2, which is dissolved in sorbent, i.e. the liquid to be atomized. The said method is based on creation of big quantity of working gas above the level of liquid to be atomized and due to this in order to increase the fullness of the package (i.e. amount of liquid to be atomized) it is necessary to produce a package with bigger volume and thicker walls. In other words, to increase its materials consumption. Whereas, according to this method, for increasing the package fullness and decreasing nonuniformal flow rate of the substance to be atomized, the working gas must be dissolved in the said substance. i.e. the atomized substance must possess an absorption capacity for the working gas, that limits the range of substances which can be atomized by means of this method.

Disclosure of the Invention

The main objective of the invention is to increase the efficiency of spraying due to usage of volumetric dispersion effect, that is production of drops of smaller dimension and maintaining of this increased degree of dispersion in the process of the aerosol package usage, increased degree of the package charging with spraying product due to decrease volume of the gas cushion of the propellant, extension of the product and propellant range, which can be dispersed by this method.

The said objective is achieved according to claim 1 by the method of creation of positive pressure in an aerosol package for spraying a gas-saturated product, including placing a product containing a sorbent to be sprayed and gas sorbed in the sorbent in the aerosol package, and by further providing inside the aerosol package a sealed casing containing a nonspraying sorbent and gas sorbed therein and comprising means for allowing gas desorbed from the nonspraying sorbent to release from the sealed casing into the aerosol package when pressure inside the sealed casing exceeds pressure outside the sealed casing at value of designated pressure differential, the nonspraying sorbent being activated charcoal and/or zeolite having a higher absorption capacity for gas than the sorbent to be sprayed, and preventing the sprayed sorbent and/or its vapors from entering the sealed casing and the nonspraying sorbent from escaping the sealed casing, thereby creating a positive pressure inside the aerosol package for dispensing the gas-saturated product.

It is possible a variant where both activated carbon and zeolite are used as nonspraying sorbent.

It is possible a variant where a solid phase of sorbed gas is used to charge said nonspraying sorbent.

It is possible a variant where a liquid phase of sorbed gas is used to charge said nonspraying sorbent.

It is possible a variant where the means for allowing desorbed gas out of the sealed casing is a spring valve.

The said method of creation a positive pressure in an aerosol package decreases an adverse effect on environment of the use of aerosol packages. Besides, fluctuations of the positive pressure of desorpted gas in the gas cavity during the process of spraying are relatively small due to the high sorption capacity of the working gas in the unchangeable quantity of sorbent, that makes it possible to provide evenness of the spraying substance, that is expecially important in varnish-dye covering.

Low values of the initial excess pressure of the sorbent gas and its excess pressure reduction in the gas capacity of the working volume make it possible the increase package filling degree of she spraying substance as well as package production economy because of the material capacity reduction, for example, by means of the thin-walled package usage.

The usage of sorption of the residual substances ( working gas, praying substances ) in sorbent decreases corrosion and other processes taking place in waste package, i.e. makes it possible to decrease harmful waste into the atmosphere and waste package influence upon the environment.

Package loading with sorbent gas, for example, with CO2 just in a solid phase makes package loading operation easier.

Elimination of the interaction between spraying substance and sorbent while turning over ( shaking, etc ) the package enlarges the quantity of the used sorbents.

It's also necessary to point out that this method enlarges the range of climate zones of the usage and/or storage working range and aerosol package exloitation because of the possibility of the sorbent usage with demanded characteristics.

In this method while operating a unit accordingly it is possible to have the dispersed liquid temperature different from the sorbent and environment temperature that is obtained by means of the dispersion of sorbent and spraying liquid as well as by means of heat isolation and/or heat absorbtion characteristics of sorbent.

Brief Description of the Drawings

On the drawings:

Figure 1: is an illustration of a sorbent positioning at the periphery of the working volume of the aerosol package.
Figure 2: is an illustration of a sorbent positioning in the inner case of the the aerosol package, isolating sorbent from dispersed substance, as well as of the sorbent positioning in the top part of the working volume above the dispersed liquid level.

Detailed Description

The given method can be realised in package for different substance dispersion ( spraying ). The construction of the aerosol unit is a sealed capacity 1, made as a cylindrical case 2 ( referring Fig. 1 and Fig. 2 ) with a bottom 3 and a cover 4, which is hermetically connected with a dispersion head 5 and a valve 6. As it is shown in Figure 1 inside of the outer case 2 there is an inner casing 7 with a working volume 8, filled with dispersed substance 9 ( liquid ).

In the cavity 10 between the outer case 2 and the inner casing 7 there is an activated charcoal ( it can be zeolite ) as a sorbent 11. At the top part of the inner casing 7 there are some holes 12 ( windows, etc. ) by the help of which the working volume 8 is communicated with the cavity 10. In the working volume 8 from its bottom up to the top there is a tube 13 for delivery of the dispersed liquid 9 to the inlet of the dispersion head 5. At the bottom 3 there is a charging valve 14 for the sorbent and sorbent gas. As sorbent gas there can be used carbon dioxide ( CO2 ) highly used in aerosol packages that answers ecological demands, put to sorbent gases of package, as well as - hydrocarbons, ethers and etc. In Figure 2 there is shown another possible positioning of the sorbent 11 inside the inner casing 7 of the package and/or at the top part of the working volume 8 above the dispersed ( spraying ) liquid level 9. It is also possible to position the sorbent 11 out of the outer case 2 of the package, but in this case it must be put in a separate sealed cavity, communicating by means of a supply main of the desorption gas with a gas cavity of the working volume ( it is not shown in the drawing ). In the top part of the case 2 there is set a charging valve 15 for a dispersed substance. Charging valves 14 and 15 can be set at any convenient place on the outer case 2. The movement schemes of the desorption gas and dispersed substance are shown by arrows in the drawing.

As the dispersed substance 9 there can be used different liquids, emulsions, suspensions and fine- dispersed powders. In the latter case dispersed substance supply 9 is provided by means of creating a pseudo-liquated layer by bringing desorption gas, desorpted from the sorbent 11, at the moment of pressure lavering in the working volume 8 when opening the valve 6 of the dispersion head 5.

The desorption gas can be brought to the working volume 8 as from the communicated with the working volume cavity 10 where there is a sorbent 11, by the way, this cavity can be got by a ring space between the inner casing 7, containing the dispersed substance 9, and the outer case 2 of the package ( see Fig. 1 ), and - from the sorbent 11, situated just in the working volume 8 ( see Fig. 2 ). As energy supply, necessary for gas desorption, from the package environment is carried out it is important to provide a thermal contact between the outer case 2 of the package and the substance of sorbent 11, which is enough for gas to exhaust with a sufficient speed, creating dynamics of recovery of demanded pressure in the working volume 8 at the moment after the package action that is to say immediately after the termination of a regular rate of spraying.

Package filling is carried out by the dispersed substance 9 and sorbent 11 and then, for example, by CO2, brought inside the cavity 10 with the sorbent either at a gas state ( at a lower temperature and heat exhaust from the package ) or as liquid ( also at a low temperature, for example, about-73 C), or as a solid phase - in a state of "dry ice".

In two latter variants ( see Fig. 2 ) it is not practically necessary to fulfill heat exhaust from the package ( about 1.5 kJ/g CO2 ), because heat absorption takes place in phase conversion of CO2 from a liquid or solid state to a sorption state.

Package filling is made taking into account, for example such quantity of CO2 supply into the sorbent cavity which is possible to be absorpted in sorbent in given loading conditions .

Sorbent volume in CO2 is determined in this case as by a sorbent type and by a demanded pressure ( P ) of CO2 in the working volume at a given operation temperature ( for example, 17 C ). For a typical value of the demanded pressure at a level of 0.15 MPa the volume ( a ) of such sorbent as activated charcoal ( type AΓ) is about 33 g of CO2 for 100 g of coal at a temperature ( t ) of 17 C. But taking into account possible increasing of initial pressure in the package up to, for example, 0.2 MPa and/or operating characteristics keeping while changing operating temperature in the given limits, the initial rate of sorbent filling by CO2 is larger, i.e. it consists of 50 g of CO2 for 100 g of sorbent.

Correlation of a and P at a constant temperature t is described by the sorption isotherm equation by Freundlich (see Timofeev D.P. "Sorption Kinetics", M Publishing House of the Academy of Sciences of the USSR, 1962, p.95-98 ). In a = In K + 1/N * In P , where a - sorbent volume by the dissolved working gas in it. P - working gas pressure,K and N - Freundlich constants, determined by the sorbent type.

Because of the fact that at the lower value of P of the working range and at the residual value a the quantity of CO2 supplied during the operation time of the package, must be sufficient for practically full displacement of the dispersed substance, it means that when having CO2 density equal to 300 1/kg ( at the pressure of 0.15 MPa and at t=17 C ), it is nessary to desorpt about 3 g of CO2 in order to displace 1 l of the dispersed liquid. Having difference of the initial and final volume of a of CO2 equal to 50-35=15 g per 100 g sorbent, it means that the quantity of sorbent must be not less than 30 g. Having filling density of sorbent at the level of 600 g/l, the volume, filled with sorbent, must not be less than 0.05 l.

Everything described above refers to the offered technical decision when the whole initial volume of sorbent is used for its supplement to the working volume. It means that there must be provided stable conditions of conservation of the sorbent quantity during operation time and, of course, - necessary heat supply to the whole volume of it ( sorbent ).

It stands to reason, that when spraying fine-dispersed powders, as it was described above, some quantity of CO2 will escape from the package at the time of powder moving to the spraying zone and to the package environment and this fact will demand usage of more specific quantities of sorbent than these given above.

In order to prevent correlations ( for example, when the package is turned over ) of the dispersed substance 9 and sorbent 11, when such a combination of them is used that the said correlation can provide an undesirable change of their characteristics, working gas supply from the cavity 10 with the sorbent 11 to the working volume 8 ( see Fig. 1 ) is fulfilled only when some given differential pressure between these spaces is obtained, that can be fulfilled by means of the work of the spring valve ( as the work of the valve 6 of the dispersion head 5 ), which opens the inlet of the working gas from volume 8 only at a lower pressure in the working volume ( for example, on the state of sraying ) and/or at an increased pressure in the cavity 10 of sorbent ( for example, at temperature increasing in this cavity ).

An important quality of the usage of sorbent with an absorption capability higher in comparison with that of the dispersed substance, is an opporunity to prevent a package working gas ( after the operation usage of this package ) escapement into the environment, for example, when the case is damaged ( because, in particular, of corrosion ). This opportunity is obtained by means of the environment temperature decreasing, for example, when transporting utilised package into cold climate zones. When necessary it is even possible to organize a processing treatment of utilised package in such a way that when package opening takes place, the temperature decreases up to the value, when the considerable part ( up to 80-90 % ) of the working gas is again sorpted in sorbent and that's why can be used again as well as sorbent itself.

The demanded decreasing of the temperature is determined by the following dependence ( see: Stolyarevskii A.Y. "Secondary Energy Accumulation" in the Collection "Atomic - Hydrogen Energetics and Technology", edition 4, M. Energy - Edition, 1982, p. 95 ): In P = - A * ( t + 273 ) ** ( - 1 ) + B where A and B - are parameters of the given sorbent, P - residual pressure of the unsorpted gas.

According to the invention as sorbent there can be used activated charcoal, characterised by a rather high absorption capability as for as CO2 is concerned and relatively low price, as well as zeolite, the characteristics of which can provide higher pressure P at a given working temperature.

Finding of grade and/or combination of different sorbent types among activated charcoal and/or zeolite ( for example, charcoal + zeolite) permits to optimise operation condition.

For convenient loading of the package there can be used liquid sorbents as well as in combination with solid ones in the state of which there can be used some organic combinations, in particular, dimethylethertetraethylenealcohol or halogenides.

Claims

A method of creation of positive pressure in an aerosol package (1) for spraying a gas-saturated product, including placing a product containing a sorbent (9) to be sprayed and gas sorbed in the sorbent in the aerosol package, characterized by further providing inside the aerosol package a sealed casing (10) containing a nonspraying sorbent (11) and gas sorbed therein and comprising means (12) for allowing gas desorbed from the nonspraying sorbent (11) to release from the sealed casing into the aerosol package (1) when pressure inside the sealed casing (10) exceeds pressure outside the sealed casing (10) at value of designated pressure differential, the nonspraying sorbent (11) being activated charcoal and/or zeolite having a higher absorption capacity for gas than the sorbent (9) to be sprayed, and preventing the sprayed sorbent and/or its vapors from entering the sealed casing (10) and the nonspraying sorbent (11) from escaping the sealed casing (10), thereby creating a positive pressure inside the aerosol package (1) for dispensing the gas-saturated product.
The method according to claim 1 wherein both activated carbon and zeolite are used as nonspraying sorbent (11).
The method according to claim 1 wherein a solid phase of sorbed gas is used to charge said nonspraying sorbent (11).
The method according to claim 1 wherein a liquid phase of sorbed gas is used to charge said nonspraying sorbent (11).
The method according to claim 1 wherein the means for allowing desorbed gas out of the sealed casing (10) is a spring valve.