WO2003020326A1

WO2003020326A1 - Methods, devices and compositions for the sustained release of chlorine dioxdie

Info

Publication number: WO2003020326A1
Application number: PCT/US2002/027369
Authority: WO
Inventors: Patrick H. Kilawee; Daniel N. Tallman; Leonard John Kadlec; John E. Thomas
Original assignee: Ecolab Inc.
Priority date: 2001-08-28
Filing date: 2002-08-27
Publication date: 2003-03-13
Also published as: WO2003020326B1; CA2457344C; EP1418952A1; CA2457344A1

Abstract

A device and method for cleaning and deororizing a unit having an enclosed space not otherwise easily accessible for cleaning and doedorizing. A variety of containers holding compositions for generating an antimicrobially active gas may be employed therein. One such container includes a unitary container housing having a plurality of sealed compartments. Each compartment contains a composition for generating an antimicrobially active gas upon exposure to moist air. The container may be employed in other applications as well.

Description

METHODS, DEVICES AND

SUSTAINED RELEASE OF CHLORINE DIOXDIE

FIELD OF THE INVENTION The present invention relates to improvements in systems for the sustained release of chlorine dioxide.

BACKGROUND OF THE INVENTION

Chlorine dioxide in low concentrations, i.e. up to 1,000 ppm, has long been recognized for its utility and effectiveness as an antimicrobial, i.e. fungicide or bactericide, and as a deodorant. In the presence of relatively low concentrations of chlorine dioxide, odiferous chemicals are oxidized to compounds which have essentially no odor. Such compounds include, for example, aldehydes, amines and thiols which are oxidized respectively to alcohols or acids, nitro compounds or various intermediates such as nitroso compounds, and to disulfides or oxides of sulfur. At higher levels than required for deodorizing, chlorine dioxide may act as an antimicrobial.

It is particularly useful where it is desirable to reduce the antimicrobial population and reduce noxious odors on and around foodstuffs for several reasons. First of all, chlorine dioxide generation does not result in the noxious byproducts such as chloramine or chlorinated organic compounds that can be produced when elemental chlorine is utilized for the same or similar purposes. Secondly, chlorine dioxide gas is also generally considered as safe for human contact at concentrations effective for deodorization and for most antimicrobial applications because the required concentrations are so low. Thus, if a low concentration of chlorine dioxide gas can be maintained in contact with fresh produce for several days during shipping from the farm to the local retailer, the rate of spoilage of the produce can be decreased.

Chlorine dioxide generation may also be employed for reducing antimicrobial populations and deodorizing around units which have automatic water flow systems such as automatic ice making machines. One such problem that occurs in such units is the formation and build-up of various biological growths including molds, yeast, fungi, slimes, other microbiological growths, and so forth. These microbiological growths, molds, yeast, fungi, and slimes form on the water-ice system surfaces, and can impede the flow of water through the system and can cause decreased heat transfer efficiency, particularly on the evaporator plates nd"ice"foWiny by as the type described in US 5,289,691. However, the automatic cleaning/sterilizing system as described therein, does not address the fouling that may occur on the inside of the unit in the upper head portion above the condenser/ice making unit. Cleaning of a head portion in this type of machine may require removal an access panel by means of multiple screws. Cleaning the corners of the head space manually can be difficult as parts of the ice making machine required for operation such as the water pump, are located in this area further compounding the difficulty of cleaning. Furthermore, the head space is a better incubating environment for microbial growths than the ice bin itself because the temperature is higher and the humidity is high. In this type of application, it may be desirable to generate chlorine dioxide on a much smaller scale and may involve removal

There are several methods which have been suggested for generation of chlorine dioxide. One method is to use a solid mixture of a metal chlorite and an acid in a liquid, aqueous environment. A second method combines a metal chlorite and a solid acid where chlorine dioxide gas is released under dry conditions. A third system employs the combination of a metal chlorite and a solid organic anhydride to generate a high concentrated flow of chlorine dioxide which must be diluted with a constantly flowing stream of inert gas. Such solid reagent systems, however, have a couple of disadvantages.

Typically, upon mixing there is a sudden, highly concentrated stream of chlorine dioxide generated, and the mixture of reactants, if not properly contained and kept moisture free, produce chlorine dioxide prematurely reducing the shelf life of the reactants.

Methods for the controlled release of chlorine dioxide gas have been developed for purposes of both deodorization and for reduction of microbial populations. For instance, US 6238643 describes a method of producing an aqueous solution of chlorine dioxide from the reaction of a metal chlorite and an acid forming component which do not react to produce chlorine dioxide in the substantial absence of water. The reactants are separated from liquid water by a membrane which allows the controlled passage of liquid water and/or water vapor into contact with the reactants.

The chlorine dioxide thus generated passes out through the membrane into the liquid water to produce the desired aqueous solution.

US 6077495 describes a method, composition and system for generating chlorine dioxide gas in a controlled release manner by combining at least one metal chlorite and a dry solid hydrophilic material that

^yi presence of water vapor, but does not react with the metal chlorite in the substantial absence of liquid water or water vapor to produce chlorine dioxide gas in a sustained amount of from about 0.001 to 1,000 ppm. US 5091107 describes methods and devices for the production of controlled quantities of chlorine dioxide at concentrations which are effective to function as a deodorant or a germicide whereby aqueous chlorite compositions such as aqueous sodium chlorite are brought into contact at a controlled rate through capillary means, e.g. a wick with an absorbent pad containing acid or other reactant which will react with the chlorite and form chlorine dioxide.

US 5974810 describes a method and composition for producing ice having substantially no undesirable taste and odor characteristics comprising freezing ice in the presence of chlorine dioxide gas.

US 6077495 describes a method, composition, and system for generating chlorine dioxide gas in a controlled release manner.

SUMMARY OF THE INVENTION

The present invention relates to improvements in systems for the generation of antimicrobially active gases, in particular, chlorine dioxide. In one embodiment, the present invention describes a method and device for reducing the population of microbes in units which have enclosed spaces not easily accessible for cleaning/deodorizing in a convenient and efficient manner. An example of such a unit is the head portion of an ice machine.

More particularly, the unit of the present invention has an interior and an exterior. The unit also has an access port which may be opened from the exterior of the unit to permit placement and replacement of a container which is permeable to liquid water or water in vapor form and which contains a composition for generating an antimicrobial active gas upon exposure to water or water in vapor form. The unit has a device for holding the container which is accessible through the access port which retains the container within the interior of the unit at a location which is exposed to ambient air within the interior of the unit.

In some embodiments of the present invention, the unit has a top and a front and the holder is in the front or top of the unit. The unit may also have sides and/or a back or bottom in which the holder may be placecr.^'l,Sαirably]^,fniS^lnβrøef'isFin^,'a -^ '"' ^{, '3}" convenient location which is easily accessible.

In one particular embodiment, the container is in the form of a sachet, bag or packet, and the composition generates chlorine dioxide gas upon exposure to water in vapor form or moisture.

The container may also be in the form of a unitary container housing which has a plurality of pockets which are independently openable, each pocket containing a composition for producing an antimicrobially active gas upon exposure to water or water vapor such as from ambient air. Suitably, the composition is a dry solid, but liquids may be employed as well, although it will probably require separation of the reactants until use. Dry/liquid combinations of reactants may also be employed. The unit may also include an indicator device activated upon each placement or replacement of the container, which provides a signal on the exterior of the unit when the container needs replacement. The present invention is particularly useful in enclosed units wherein it is difficult to access the interior for cleaning and sanitizing. For instance, the device is useful in refrigeration units, storage lockers of any type wherein access is not easily gained, and so forth.

In another embodiment, the present invention relates to a container in which the compositions for generating an antimicrobially active gas are divided into a plurality of separate portions, each of which is contained in a separate sealed compartment of a unitary container housing. The sealed compartments are sequentially unsealed to expose the contents to the environment around the container housing in response to a predetermined stimulus event. The container can be employed in combination with the holding device described above.

The present invention, in another embodiment relates to a device for the generation of an antimicrobially active gas including a unitary container housing having a plurality of sealed compartments each of which contains a composition which will gradually release chlorine dioxide upon exposure to moist air, a compartment opener operable on the unitary container housing to open a compartment in sequence in response to an opening signal and a controller operable to periodically issue a opening signal to the opener. Again, the device may be employed in combination with the holder, described in some of the embodiments above. The reactants may be in solid form.

only Zsilje ^g compartment is required. The reactants may also be in liquid form, or one reactant may be a liquid and one reactant a solid. If at least one reactant is in liquid form, a barrier may be provided between the reactants, thus requiring two compartments be opened in order to allow the reactants to mix.

In one embodiment, the present invention relates to a device and method for the controlled and sustained release of an antimicrobially active gas including a power supply, an electrical switch, a plurality of conductors, a controller and a container having a top and bottom and housing a plurality of sealed pockets. Each pocket contains the gas generating composition of the present invention. The conductors are connected to the electrical switch and each terminate in an electrode. Each electrode is attached to a sealed pocket. The controller is operatively connected to the power supply and to the electrical switch, and is capable of directing the switch to apply power sequentially to each conductor for a first predetermined time interval. There is a second predetermined time interval between each application of power to each conductor.

Using the device as described above allows for sequentially supplying power to each of the conductors for a first predetermined time interval such that the sealed pockets may be opened sequentially. There is a second predetermined time interval between each application of power to each conductor. Upon application of power to the conductors and thus to each electrode, the sealed pockets open, exposing the contents to atmospheric moisture thereby initiating the gas generating reaction.

The device may be placed in the holder of the enclosed units described above. The methods, devices and compositions of the present invention are particularly useful for the controlled and sustained release of chlorine dioxide over a period of time for reducing antimicrobial populations, and for deodorizing.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of an ice machine showing one embodiment of the present invention.

Fig. 2 is a different view of the same ice machine as shown in Fig. 1.

Fig. 3 is a perspective view of an embodiment of the device of the present invention. Fig. 4 is a perspective view of an alrern i fc rvM'Me^eM the present invention.

Fig. 5 is a schematic of one embodiment of a device according to the present invention. Fig. 6 illustrates an embodiment of a container which may be used in the present invention.

Fig. 7 illustrates an alternative embodiment of a container which may be used with the device of the present invention.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

While this invention may be embodied in many different forms, there are described in detail herein specific embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. The present invention is directed to devices, methods, and compositions for the controlled and sustained release of a deodorizing and/or antimicrobially active gas over a period of time. The reactants and device of the present invention are designed such that the release of the gas is accomplished at a rate which results in low concentrations of the gas being released over an extended period of time. The rate and duration of the release of gas may be controlled using the composition and device of the present invention. This is controlled by controlling the exposure rate of a chemical composition to conditions which trigger the reaction which produces the gas, such as ambient moisture.

Fig. 1 illustrates one embodiment in which a device according to the present invention is employed in combination with an ice producing machine shown generally at 10. The head portion 25 of ice machine 10 houses an access port 12 which provides access to the interior (not shown) of the ice machine. Ice machine 10 also has a holder 15 for holding a container which has a composition that generates an antimicrobial active gas upon exposure to water or water in vapor form. The holder 15 in this embodiment is in the form of a drawer which slides easily through the access port 12 and into the interior (not shown) of the head portion 25 of the ice machine 10. Fig. 1 also shows the front access panel 27 which would require removal on a much more regular basis for sanitizing/deodorizing of the

inVhiad''pόftϊiiri^,'i5 without the access port 12 and holder 15 of the present invention.

In the embodiment shown in Fig. 1, the access port/holder is in the form of a slot/drawer. However, any access port and holder may be utilized in the present invention to provide easy access to the interior of an enclosed space. For instance, removable trays, pivoting pockets, slots, pocket doors, swinging doors, and so forth may be utilized. The access port/holder must allow air to flow around the container and must not be enclosed so that the gas may escape into the interior of the enclosure.

The access port/holder may suitably be provided on the front, top or side panels of the enclosed unit.

Fig. 2 shows an expanded view of the same ice machine 10 as shown in Fig. 1. The holder 15 in this embodiment also shows an indicator device 35 which is activated upon placement or replacement of the container holding the composition that generates the antimicrobial active gas upon exposure to water or water in vapor form. This indicator device 35 may be in the form of a red/green LED, for instance.

Fig. 3 shows a more expanded view of the holder 15 designed for holding a container having the gas generating composition of the present invention. As can be seen from the figure, the holder 15 further has perforations 30 which allow escape of the gas into the interior (not shown) of the head portion 25 of the ice machine 10. Fig. 4 shows an alternative embodiment of the present invention in which the holder 17 for holding the container having the gas generating composition of the present invention is located on the top surface 40 of the head portion 25 of the ice machine 10. The holder 17 in this instance sits inside of the access port (not shown) which cannot be seen. In this figure, the access panel 27 has been removed making the interior 35 of the head portion 25 of the ice machine 10 clearly visible. As can be seen, the interior 35 of the head portion 25 houses a water pump 45 among other things.

Ice machines of the type described above are found in US 5289691, US 5408834, US 5586439, US 5787723, US 5878583, US 6196007 B, and so forth, each of which is incorporated by reference herein in its entirety. These ice machines are intended for exemplary purposes only. One of skill in the art would understand that various modifications could be made to the ice machines described herein, and that other completely different configurations could be utilized without departing from the scope of the present invention. The device of the present invention is αesi'grleα-so^'al rø allovv efasj aetee s to the interior of an otherwise enclosed space not easily accessible for cleaning and deodorizing. Such device may be utilized in any enclosed area or machine where mold, mildew, fungi, yeast, or other bacteria may be problematic. The device may also include an indicating device or change out indicator such as a timing device which signals the need to replace the container. The indicator may provide some sort of signal in response to a predetermined time interval between openings of the access port, for instance. The device may be activated upon each placement or replacement of the container, and provides an indicator signal on the exterior of the unit when the container needs replacement. This may be in response to a predetermined time interval between openings of the access port.

The signal may be an alarm or a green/red LED that, after given time interval. The change out indicator may be provided on the front of the unit, or may be held by a secondary holder inside the first holder. As shown in Figs. 1-3, above, the indicator may be provided as a display on the front of the holder which in the embodiments shown in Figs 1-3, is in the form of a drawer.

Another method of indicating the need to change the container is to use a sticker whereby the dates for the required change are indicated.

Or, for certain gaseous substances, a detector or sense may be utilized to monitor the amount of gas in the head space inside the interior of the ice machine and when the concentration becomes too low, an alarm will sound or an LED may indicate the low concentration with a red/green color change.

While one particular embodiment described above illustrates the use of some of the inventive concepts of the present invention in a refrigeration unit, i.e. ice machine, it is important to note that the present invention may be utilized in any enclosed space not easily accessible for sanitizing/deodorizing.

Fig. 5 is a schematic diagram illustrating one embodiment of a device 50 according to the present invention The device 50 has a container 100 having a plurality of pockets 180. In this embodiment container 150 is shown with a 12-pocket configuration. The container may house any number of pockets from one on up.

Preferably, the container will house between about 4 and 30 pockets Figs 6 and 7 show alternative embodiments of the container of the present invention having 16 and 10 pockets consecutively. Such containers may have anywhere from one pocket on up. Suitably, the number of pockets may be between aDout'4'arid

limited as such.

The term pocket may also be hereinafter used interchangeably with compartment, reservoir, recess, cell, cup, dish, cavity, and the like, only to mention a few.

Figs. 6 and 7 show a unitary container 100 having a series of individual pockets 180, each of which holds the composition of the present invention. The containers 100 suitable for use herein may be, for example, configured similarly to an egg carton, ice cube tray, or the like. This invention is not limited in scope to any particular type of packaging or container which may be used in accordance herewith providing that the packaging or container is suitable for use with the device herein. Any type of package or container capable of being made to protect the composition of the present invention from the environment, in particular moisture, may find utility herein. There is an endless array of packaging and one of ordinary skill in the art would understand that the configuration, materials, and so forth of the container may be easily changed without departing from the scope of the present invention. The container or package should be configured such that it may be sealed in such a manner that the contents are protected from exposure to the environment, in particular, contact with moisture is prevented. The container suitable for use with the device described herein is generally formed from one or more materials that can be shaped and sealed to form at least one pocket which holds the gas generating composition of the present invention, and a top for sealing the composition in the pocket. Suitably, the base or bottom of the container 100 has a plurality of pockets for holding the composition of the present invention.

One specific type of package which may find utility herein is a "blister pack", a term of art known to those of ordinary skill. A blister pack system is typically described as a blister to which a lid or backing of the same or a different material may be tightly fitted and sealed near the outer perimeters of the blister and or lid, and by virtue of the outer perimeters of the blister and lid being continuously sealed to the backing material. The sealed blister prevents outside moisture in the form of vapor from coming into contact with the composition of the present invention. Examples of this type of packaging suitable for use herein may be found in rø-58u3 ^!aΛ "fj-l 000691 %™^ which are incorporated by reference herein in its entirety.

Within each pocket or "blister" is the composition of the present invention. The pocket may contain any amount of composition suitable for the particular use to which it is being put. However, for many applications, an amount of about 1 g to about 100 g in each pocket or blister will be sufficient. However, for other applications, gallon size containers, drums, and so forth may be used depending on the size of the operation.

The package or container useful herein may include a lower part having a cavity defining a composition holding receptacle, i.e. pocket 180, the composition being disposed within the receptacle, and a covering material which covers the cavity thereby enclosing the product in the container in such a way that it is impermeable to water or water vapor.

The bottom member or backing and the covering material of the container may be made of the same or of a different material. In this embodiment, the top material may be any material which may be opened through the use of an electrical current that generates heat by building of resistance in an electrode, or by heat, such as by heating a wire Suitably, in this embodiment, the top is in the form of a film or the like which is capable of being melted upon application of an energy source such as an electric current or heat. Suitably, the top is in the form of a thm film or laminate that is comprised of a polymeric material. The laminate has at least a first layer and a second layer, but may have more layers as well.

The polymeric material suitable for use herein may be any polymeric material known for use in film or laminate form such as polyolefins including polyethylene and polypropylene and copolymers and terpolymers thereof, ethylene and propylene alpha olefin copolymers and terpolymers, polyesters such as MYLAR7, cellophane, SARAN7, and so forth.

The base or bottom of the container may be manufactured of any material that is or can be made impermeable to water or water vapor including polymeric materials, laminates or composites including those having polymeric materials, paper products such as cardboard, and so forth by molding. Paper products may require further treatment, lamination, a coating, or similar for providing a moisture-proof barrier. The bottom portion of the container may be polymeric in nature Examples of materials suitable for use include polyolefins such as low density polyethylene '( ,DPE),'hϊgh density polyethylene (HDPE) and polypropylene, polystyrene, and so forth. The container base may be made by thermoforming, molding, extrusion, and so forth. Metals such as an aluminum may also find utility herein but they may tend to be corrosive. To enclose the product in such a way that it is sufficiently impermeable to water or water vapor, the covering or top may be sealed to the container 100 in such a way that each individual pocket 180 is sealed. Preferably, the covering material is in the form of a film or laminate (not shown) wherein a single piece covers and seals all of the pockets 180. The film or laminate may be in whole or in part made of polymeric materials. If it is in the form of a laminate, it may also include a foil-type of material, for instance. The seal may be formed by heat sealing or adhesively, for example. Any method known to those of skill in the art for providing an adequate seal may find utility herein. The method of sealing should provide a moisture-proof barrier thus protecting the composition within the pocket from premature exposure to ambient moisture Each individual pocket 180 may be sequentially unsealed to expose the contents to ambient moisture to initiate the gas forming reaction. This may be accomplished through the use of an electrical circuit having a series of conductors 240 and electrodes 260, each conductor 240 terminating at an individual pocket 180. A conductor 240 runs from an electrical switch box 220 or similar device to the center of each pocket 180 and terminates in an electrode 260. The conductor may be in the form of a wire such as a 20-gauge wire. Higher gauge wires may be used, as well as lower gauge wires. However, wires having a smaller diameter, i.e. higher gauges, may have more of a tendency to break with heat. An electrical charge may be sent to each individual electrode 260 at a different time. Each conductor 240 is terminated with an electrode 260. Electrode 260 is in contact with the material covering each pocket 180. If one reactant is a liquid, and a barrier (not shown) is provided between reactants in each pocket 180, then two electrodes 260 may be provided to each pocket, one which may open the pocket 180 itself, and one which would open the barrier, allowing the reactants to intermix. In this embodiment, either one or two conductors 240 may be provided to each pocket. If two conductors 240 are provided, then an electrical charge may be sent to each electrode 260 at substantially the same time. If one conductor 240 is provided, it may branch at the end into two conductors 240. In this instance, a single electrical charge would be requirld'to pen b'o'M

barrier.

If one reactant is a liquid, and a barrier (not shown) is provided between reactants in each pocket 180, then two electrodes 260 may be provided to each pocket, one which may open the pocket 180 itself, and one which would open the barrier, allowing the reactants to intermix. In this embodiment, either one or two conductors 240 may be provided to each pocket If two conductors 240 are provided, then an electrical charge may be sent to each electrode 260 at substantially the same time. If one conductor 240 is provided, it may branch at the end into two conductors 240 In this instance, a single electrical charge would be required to open both the pocket 180 and the barrier.

If the covering material is in the form of a film, it may be attached to the film. If the covering material is in the form of a laminate, electrode 260 may be sandwiched in between the layers of the laminate Alternatively, electrode 260 may be sandwiched in between the covering material (not shown) and the bottom part of container 150 where the seal is formed. Resistance is created m the electrode 260 at the termination of each conductor 240 The resistance thus created causes the conductor 240 to heat up and melt the film or laminate thus opening pocket 180 and exposing the contents to the atmosphere. The resistance created at the terminal end in each cell causes the wire to heat up, thereby melting the polymeric film or laminate The contents are exposed to ambient moisture, thus starting the reaction to release chlorine dioxide

Switch 220, in this embodiment, is in turn in communication with a microprocessor 140 which is in turn connected to a power supply 120 which may be in the form of a DC or an AC power source including a 24V AC power supply or a 9-volt battery, for instance. Microprocessor 140 may have program memory 160 as well as a timing device 200. The timing device 200 in this embodiment 200 is shown in the form of a real time clock, but may be in the form of a counter, or other timing device Microprocessor 14 may be further equipped with a reset button (not shown) to be used when the entire contents of all of the pockets 180 have been spent and the container 150 may be changed At periodic intervals, the microprocessor 140 directs electricity to each conductor 240 in sequence The time interval will ordinarily depend on the length of time for the reactants of each pocket 180 to be used The microprocessor 140 may also be connected to a timing device and/or to a

'''^' " concentration of gas. The monitor may produce a signal that will indicate when the reaction in the compartment is spent, or when chlorine dioxide concentration is too low, and thus when the next compartment should be unsealed. The device may also include a monitor and signal for change out of the container itself to notify the use when the entire container requires changing. The signal may be in the form of an alarm or LED, for instance.

The device as described above allows each pocket or cell to be opened in series. In this manner, the device provides for a longer term method of releasing antimicrobial and/or deodorizing gas.

Alternatively, the device may have an on/off switch to allow for manual operation. In this embodiment, the switch box 220 may also be connected to a monitor having a signal such as an LED set to the timing device 200 that will indicate when the reaction in the compartment is spent, and thus when the next compartment should be unsealed.

Of course, the container 100 may simply be equipped with a timing device indicating when each pocket should be opened. In this instance, the device can be manually opened without requiring electrodes, battery and so forth.

The description and figures above are intended as exemplary of the present invention only, and are not intended to limit the spirit and scope of the present invention.

Any composition capable of producing an antimicrobially active gas may be utilized in the above described devices and methods of the present invention. Most conveniently, this is accomplished by exposing the composition to liquid water or water in vapor form. Such generation of gas is desirably accomplished in a controlled release manner in amounts effective to reduce microbial populations including mold, yeast, fungi, and other microbes. In some instances, the gas may also act as a deodorant thereby reducing offensive and noxious fumes.

Examples of gases that may suitably be generated in aqueous solution in this fashion include, but are not limited to, chlorine dioxide, halogens including chlorine, bromine and iodine, ozone, ethylene oxide, or other vapor emitting corrosion inhibitors.

Suitably, the compositions useful herein are in the form of dry solids. However, the reactants in a liquid form may also be used or a combination of a solid/liquid may also be employed. If a liquid is empi'oryed ^'specilF Hcautfbris for^{αι ™} keeping the reactants separate may be required such as a barrier membrane, for example.

Typically, generation of a gas in this manner will involve at least two reactants. For example, in some embodiments of the present invention, chlorine dioxide is generated by using a mixture of at least one metal chlorite and at least one second material which is capable of reacting with the metal chlorite to produce chlorine dioxide gas in the presence of water or water vapor, but not in the substantial absence of liquid water or water vapor, typically, an acidic component. At the time of use, the mixture is exposed to atmospheric water vapor resulting in the production of chlorine dioxide gas at a sustained concentration of about 0.025 to about 1000 ppm.

If a metal chlorite is employed in the present invention, any suitable metal chlorite may be employed. Suitably, the metal chlorites are alkali metal chlorites, such as sodium chlorite and potassium chlorite. Alkaline earth metal chlorites can also be employed. Examples of alkaline earth metal chlorites include barium chlorite, calcium chlorite, and magnesium chlorite. Most suitably, the metal chlorite is sodium chlorite. The material for reacting with the metal chlorite is suitably a dry hydrophilic material as described in US 6077495 incorporated by reference herein in its entirety. Examples of such dry solid hydrophilic materials suitable for reacting with the metal chlorites include, but are not limited to, synthetic zeolites, such as A, X, Y, and mordenite; natural zeolites such as chabazite and clinoptilolite; hydrous clays, such as bentonite, kaolin, attapulgite and halloysite; calcined clays, such as metakaolin, spinel phase kaolin, calcined bentonite, calcined halloysite, and calcined attapulgite; acidified synthetic zeolites, such as A, X, Y, and mordenite that have been contacted with one or more acidic solutions containing sulfuric acid, hydrochloric acid, nitric acid, or other acidic compound (e.g. calcium chloride) so that the pH of the resulting aqueous phase of the mixture is below 10.5; acidified natural zeolites such as chabazite and clinoptilolite; acidified clays, such as bentonite, kaolin, attapulgite and halloysite that have been contacted with one or more acidic solutions containing sulfuric acid, hydrochloric acid, nitric acid, or other acidic compounds (e.g. lanthanum chloride) so that the pH of the resulting aqueous phase of the mixture is below 10.5; acidified calcined clays, such as metakaolin, spinel phase kaolin, calcined bentonite, calcined halloysite, and calcined attapulgite that have been contacted with one or more acidic solutions containing sulfuric acid, hydrochloric acid, nitric acid, or other acidic compounds (e.g. acetic acid) so that the pH of the resulting aqueous phase of the mixture 'il below Wsj'sk s, sAch'as ^!i " " " " aluminum sulfate, magnesium sulfate, calcium carbonate, and particularly deliquescent acidic salts, such as calcium chloride, magnesium chloride, lithium chloride, and magnesium nitrate, solid acids, such as boric acid, tartaric acid and citric acid, organic acid anhydrides such as phthalic anhydride, maleic anhydride, succinic anhydride and glutaric anhydride; and mixtures thereof

In one embodiment, the reactants acidified calcined metakaolin clay and sodium chlorite, both of which are in solid form

The mixture of metal chlorite, an acidic material, and any other desired additives may be packaged for shipment and storage in containers made of materials which are resistant to the passage of liquid water and water vapor Examples of such materials include metal cans, glass jars, foil pouches, and barrier layer polymer laminates, as well as the multi-pocket devices described above The mixture of metal chlorite, an acidic material, and any other desired additives may be packaged for shipment and storage in containers made of materials which are resistant to the passage of liquid water and water vapor.

Alternatively, a self-contained composition for the generation of gas may be utilized in the present invention wherein a shrink-wrapped container is equipped with a battery such as a 9-volt battery, and a circuit. A charge causes the wire to heat and melt the shrink wrap thereby exposing the chemicals to the moisture in the ambient air The battery may be further equipped with a timing device

For many applications, the amount of reactants utilized may suitably be between 50 and lOOg with sodium chlorite being about 5 wt-% of the composition and the acidified clay being about 95 wt-% of the composition In an embodiment in which the device includes a plurality of sections or pouches separated from one another, each pouch may comprise anywhere from about 1 gram up to about 100 grams, but may also be suitably in the range of about 50g to lOOg of reactants As shown in Fig 2, the device may be a 12-pocket pack

Chlorine dioxide delivery in a suitable embodiment maybe about 1-2 ppm in the first several hours, about 0 5 to 1 0 ppm (t₂) after about 24 hours, and levels off to about 0.1 ppm shortly thereafter In the case of the container described above, particularly those having multi-pockets, the circuit may be set with a with a timing device such that the next pouch may be activated daily, every other day, every few days, on a weekly basis, and so forth, or may be set to alanrr'an operator to the'^{' '}fact tnat''a"ne^'w pocket needs to be opened in the case of a container which requires manual opening.

At the time of use, the mixture may then be exposed to atmospheric water vapor resulting in the production of chlorine dioxide gas at a sustained concentration of about 0.025 to about 1000 ppm. The generation of chlorine dioxide using such methods are described, for example, in US 4547381, US 4585482, US 5974810, US 5650446, US 5695814, US 5707739, US 5091107, US 5888528, US 5922776, US 5965264, US 5,980826, US 6046243, US 6077495, and so forth, all of which are incorporated by reference herein in their entirety. Chlorine dioxide can act as an antimicrobial agent by reducing the population of microbes present, and can also act as a deodorant by reducing noxious compounds including, for example, aldehydes, amines and thiols which are oxidized respectively to alcohols or acids, nitro compounds or various intermediates such as nitroso compounds, and to disulfide or oxides of sulfur. The mixture of the metal chlorite and the acidic material may be used as a powder, used as formed shapes, or packaged and retained for use in any material which is gas permeable.

Suitably, the packaging material retained for use is substantially impervious to liquid water, but is permeable to water in vapor form. One particular class of materials suitable for use herein include micro porous nonwoven hydrophobic polymer sheet materials such as TYVEK® nonwoven polyethylene available from DuPont and GORETEX® woven polytetrafluoroethylene available from W.L. Gore & Associates both of which are commercially available. Such materials are typically flexible in nature and are quite suitable for making packages in the form of a sachet, bag or packet.

These materials allow water vapor to enter into the package and react with the mixture and also enable the resulting gas, for instance, chlorine dioxide gas, to be released from the package and enter the atmosphere. Particles larger than about 0.3 microns, for instance, are filtered or blocked, and not allowed to pass through the fabric. Such materials are substantially impervious to water in liquid form. Such materials may require packaging, storage and shipment in a container that would not allow the passage of moisture in any form in order to prevent a premature reaction. Shrink wrap is one form of packaging that may be utilized in

or similar form is used, these could be available in 6-, 12- and 24-pack cases.

Materials that do not allow water to pass in any form may also be utilized in a packaging form that would require opening prior to use. Such a package may be more difficult to utilize because the transfer of water vapor into the package would not be as evenly distributed as in the case of a material permeable to water in vapor form.

In one embodiment, the reactants acidified calcined metakaolin clay and sodium chlorite, both of which are in solid form. The reactants are packaged in a sachet form in either TYVEK® or GORETEX® materials. The amount of reactants utilized may be between 50 and lOOg with sodium chlorite being about 5 wt-% of the composition and the acidified clay being about 95 wt-% of the composition. Chlorine dioxide delivery using this embodiment is about 1-2 ppm in the first several hours, about 0.5 to 1.0 ppm (Wi) after about 24 hours, and levels off to about 0.1 ppm for about 30 days. The sachets would require changing about every 30 days. The rate at which chlorine dioxide is generated will, to a certain extent, depend on the relative humidity of the environment in which the reactants are placed. For instance, the method of the present invention can be conducted under low humidity conditions (e.g. 10% relative humidity) up to 100% high humidity conditions. As previously indicated, the amount of chlorine dioxide gas generated per given amount of the mixture will depend, in part, on the relative humidity of the surrounding atmosphere. In general, higher humidity will result in a higher concentration of chlorine dioxide gas.

The present invention may be utilized in any application where it is desirable to deodorize, or where it is desirable to reduce the population of microbes present including fungi, molds, yeast, slimes, bacteria, and so forth, other microbiological growths, and so forth.

The device and method of the present invention for the generation of antimicrobial gases may be used to treat liquids, solids, and gaseous environments. Examples of gaseous environments which may be treated include those containing noxious and/or objectionable gases such as animal environments, smoke-laden environments (e.g. tobacco smoke) such as nightclubs, exhaust systems from noxious gas producing facilities (e.g. chemical plants), and so forth.

Using the present invention, the amount of chlorine dioxide generated may vary from anywhere between about 0.01 to about 1,000 ppm, with deodorizing typically occurring at the lower end of the concent trbn la^ήgl-ϋF H e aϊ"lu^'θ pit or less. See for example, US 5974810 incorporated by reference herein in its entirety.

The success of the method of the present invention for treating ice machines depends on the level of chlorine dioxide that is present in the head space of the ice machine, i.e. the space above and around the reactants.

The amount of chlorine dioxide in the head space is also dependent on the temperature of the water. When the water temperature is less than about 50° F, considerably less chlorine dioxide is observed in the head space. This of course is a result of the very low vapor pressure of chlorine dioxide. The materials of this invention may also be used to help prevent the incorporation of unwanted substances (including possibly toxic substances) which may affect the taste and odor in ice produced by ice machines, particularly in large volume ice production such as in commercial applications. It is well known that after prolonged use, the ice producing chambers of such ice machines can accumulate microbes (including pathogenic microbes) and microbial films which may emit harmful or unpleasant smelling and tasting gaseous and other byproducts. Such byproducts can accumulate in or on the ice being produced either before, during or after the water freezing process. However, it is believed that, the taste and odor of the ice being produced will be less affected and will not deteriorate to a substantial degree when materials of the present invention are used to generate and maintain a concentration of chlorine dioxide gas from between about 0.01 to about 10.0 ppm, and preferably from about 0.01 to about 1.0 ppm within the ice producing chamber of an ice machine. It is believed that the chlorine dioxide gas produced in accordance with the practice of this invention, destroys the unpleasant smelling and tasting microbial byproducts so that they do not contaminate the ice. At higher concentrations of chlorine dioxide gas, the microbes themselves may be destroyed by the chlorine dioxide gas.

Optionally, other items may be utilized with the present invention. For instance, a desiccant pad may be utilized for moisture removal, sodium bicarbonate may be used for odor removal, a monitoring device for monitoring temperature and humidity, a change out indicator, and so forth. Such items may be easily placed within the interior of enclosed units that are not easily accessible from the exterior of the unit using the present invention. These items could be provided in a secondary holder within the first holder, for instance, or they may be provided in their $wrϊ a'ccy' (ϊrτ/rio'I^'dϊr" ^ -^ ^^'Ά "^:il combination.

If transient high concentrations of chlorine dioxide gas in undesirable, an inert gas stream can be used to reduce the concentration of chlorine dioxide gas in the atmosphere for any of the devices and methods described above.

The present invention is particularly suitable for the treatment of environments on and around foodstuffs including processing plants, storage lockers, transportation vehicles and so forth.

Other environments in which any of the inventive concepts of the present invention may find utility include, but are not limited to, other refrigeration and beverage units including wet bars and soda machines, produce storage lockers, gym lockers, cleaning equipment/supply lockers, lockers in gyms, garbage receptacles, closets, and so forth. Other types of applications in which the inventive concepts may be used include seasonal vacation homes which are often closed up for certain periods of time, bathroom stalls, in restaurants ars such as in the wet bar area, and so forth.

The following non-limiting examples further illustrate the inventive concepts of the present invention.

EXAMPLES

In the following examples, each sachet contained 95% acidic metakaolin calcined clay available from various sources and 5% sodium chlorite. The sachets were manufactured of SENTREX® breathable, water-proof material available from Kimberly-Clark in Neenah, WI.

Example 1

Two 50 g sachets were mounted in the condenser area of a model # Q400 ice machine manufactured by Manitowoc Co. in Manitowoc, WI. The condenser area measured 3.25 cu feet. The ice machine produces 400 lbs of ice per day. Dragger tubes were utilized to measure the chlorine dioxide level in the top of the ice machine and in the door two weeks after installation of the sachets. The concentration of chlorine dioxide was found to be 0.14 p.m

the ice machine.

Example 2

Four 50 g sachets were installed in a Manitowoc Ice Machine Model A400. The chlorine dioxide concentration was measured in the top of the ice machine and in the door 24 hours after installation and 168 hours after installation. The following results were achieved

Table 1

The amount of chlorine remaining in the sachets was measured using titration methods and calculated as a percentage of residual chlorite and found to be 64%, 57%, 83% and 62% remaining.

The above disclosure is intended for illustrative purposes only and is not exhaustive. The embodiments described therein will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto.

Claims

CLAIMS. IF" C TV U S 10 E Ξ 736 '9

1. A unit comprising an enclosed space not easily accessible for cleaning and deodorizing, having an interior and an exterior, the unit comprising an access port in the unit openable from the exterior of the unit to permit placement and replacement of a container permeable to water or water vapor, holding a composition which generates an antimicrobially active gas upon exposure to water or water vapor; and a holder for said container, accessible through the access port, which retains the container within the interior of the unit at a location exposed to the ambient air within the interior.

2. The unit of claim 1 wherein said container comprises: a unitary container housing having a plurality of sealed compartments which become permeable to water or water vapor upon opening, each of said sealed compartments containing a composition which will gradually release an antimicrobially active gas, a compartment opener operable on said unitary container housing to open said compartment in sequence in response to an opening signal and a controller operable to periodically issue a opening signal to the opener.

3. The unit of claim 1 or 2 wherein said gas is a halogen, chlorine dioxide, ozone, or ethylene oxide.

4. The unit of claim 1 or 2 wherein said composition comprises sodium hypochlorite and an acidic component.

5. The unit of claim 1 wherein said holder is a drawer, pivoting pocket, slot or tray.

6. The unit of claim 1 further comprising an indicator device activated upon each placement or replacement of said container, the indicator device providing an indicator signal on the exterior of the unit when the container needs replacement.

7 A unit as in claim 6 wherein said indicator de' ice''p ovitle^,s ϊaiiϊ indicator ^■sighai in response to a predetermined time interval between openings of said access port.

8. A unit as in claim 7 wherein said indicator signal is a light or an alarm activated upon passage of said time interval.

9 The unit of claim 1 said unit having a top and a front wherein said holder is in the top of front of said unit.

10. The unit of claim 1 wherein said container holds from about 50 g to about 500 g of said composition.

11. The unit of claim 1 wherein said container is in the form of a jar, can, pouch, barrier layer polymer laminate package, a container comprising a housing with a plurality of sealed pockets or sachet.

12. The unit of claim 11 wherein said container comprises a housing with a plurality of sealed pockets sealed with a thermoplastic film.

13. The unit of claim 11 wherein said sealed pockets are opened manually or with an electrical signal.

14. The unit of claim 1 or 2 wherein said composition is a solid, a liquid or a combination thereof.

15. The unit of claim 1 wherein said container is comprised of a microporous nonwoven hydrophobic polymer sheet material.

16. The unit of claim 1 wherein said container is comprised of a nonwoven polyethylene or a nonwoven polytetrafluorethylene.

17. A unit as in claim 1 wherein said access poA^''ιlι:cmfigϋed^l'sτJ E'th^Fthe^' corϊterits within the interior of the refrigeration unit, other than said container, may not be accessed therethrough.

18. A unit as in claim 1 wherein said access port and said holder for said container together form a drawer in said unit.

19. A unit as in claim 1 wherein said drawer has a perforated bottom to facilitate access of the interior air within the unit to the container.

20. A unit as in claim 1 wherein said unit is a refrigeration unit.

21. The unit of claim 20 wherein said refrigeration unit is an ice making machine, a soda machine, a refrigerator or a freezer.

22. A unit as in claim 1 wherein said unit is a locker, closet or garbage receptacle.

23. A device for delivering an antimicrobially active gas comprising a unitary container housing having a plurality of sealed compartments each containing a dry composition which will gradually release chlorine dioxide upon exposure to moist air, a compartment opener operable on said unitary container housing to open a said compartment in sequence in response to an opening signal and a controller operable to periodically issue a opening signal to the opener.

24. The device of claim 23 in combination with a holder in an enclosed unit, said holder accessible from the outside of said enclosed unit.

25. The device of claim 24 wherein said holder is in the form of a drawer, pivoting pocket, slot or tray.

26. The device of claim 23 wherein said controller issues an opening signal in response to a timing program. P C S liJ l ii O iii it J! / ...!! H i ^l!'"JI

27. The device of claim 23 further comprising a monitor of gas concentration and said controller is configured to issue a said opening signal in response to a depleted concentration of gas indication received from said monitor.

28. The device of claim 23 wherein each of the compartments is sealed by a thermoplastic film cover, and said compartment opener comprises a heating unit adapted to melt said film cover in response to an opening signal.

29. A unitary container housing having a plurality of sealed compartments each containing a dry composition which will gradually release chlorine dioxide upon exposure to moist air, and each compartment being separately openable to expose its contents to the environment.

30. The container housing of claim 29 further in combination with a holder in an enclosed unit, said holder easily accessible from the outside of the unit.

31. The container of claim 30 wherein said holder is in the form of a drawer, pivoting pocket, slot or tray.

32. The container housing of claim 29 wherein each of the compartments is sealed by a thermoplastic film cover.

33. A device for the sustained release of an antimicrobially active gas comprising: a) a power supply; b) an electrical switch; c) a plurality of conductors connected to said electrical switch each of which terminates in an electrode; d) a controller operatively connected to said power supply and said electrical switch; and e) a container having a top and a bottom" housing W Mhraltt of'sea ed'¹ " " ' ' pockets, each pocket containing a composition which generates an antimicrobially active gas upon exposure to water or water vapor and wherein each electrode is attached to a pocket, wherein the controller directs the switch to apply power sequentially to each conductor for a first predetermined time interval with a second predetermined time interval between each application of power for opening said sealed pockets.

34. The device of claim 33 wherein said top is film or a film laminate having at least a first layer and a second layer.

35. The device of claim 33 wherein said electrode increases in temperature upon application of power to said conductor to a temperature sufficient to melt said film or laminate.

36. The device of claim 33 wherein said electrode is attached to said sealed pocket between said first and said second layer of said film laminate.

37. The device of claim 33 wherein said gas is chlorine dioxide, a halogen, ozone or ethylene oxide

38 The device of claim 33 wherein said composition in said each pocket comprises a metal chlorite and an acidic component.

39. The device of claim 33 wherein said power supply is a 9-volt battery or a 24V AC power source.

40. The device of claim 33 wherein said conductor is a wire of between about 12- gauge and about 30-gauge.

41. A method of generating chlorine dioxide gas comprising: providing a composition which reacts in the presence of water or water vapor to produce an antimicrobially active gas, but does not react in the absence of water or water vapor, and exposing the composition to a moist e^'ri^!VirUnmIn^lt! ^Jl " " " "' " " "^l" ^lb "^J wherein the composition is divided into a plurality of separate portions, each contained in a separate sealed compartment of a container housing, and the sealed compartments are sequentially unsealed to expose the contents thereof to the environment around said container housing in response to a predetermined stimulus event.

42. The composition of claim 41 wherein said composition is a solid or a liquid.

43. The method of claim 41 wherein said gas is chlorine dioxide, a halogen, ozone or ethylene oxide.

44. The method of claim 41 wherein said stimulus event is a time increment.

45. The method of claim 41 wherein said stimulus event is a monitor signal indicative of a depleted concentration of gas

46. The method of claim 41 wherein said sealed compartments are unsealed by an electrical current

47. The method of claim 41 wherein said composition is provided in an enclosed unit having an outside, an inside, and having a holder which is easily accessible from the outside of said unit

48. The method of claim 47 wherein said holder is a drawer, pivoting pocket, slot or tray.

49. The method of claim 47 wherein said enclosed unit is an automatic ice making machine.

50. A method for the sustained release of an antimicrobially active gas comprising the steps of a) providing a container having a plural it 'Of 'sealed 'όftlts' ealEh 'of wfec 1 9ή contains a composition which generates an antimicrobially active gas upon exposure to water or water vapor, a plurality of conductors terminated in an electrode and each electrode attached to at least one of said plurality of said sealed pockets, an electrical switch connected to said conductors which is in turn connected to a power source; and b) sequentially supplying power to each of said conductors for a first predetermined time interval with a second predetermined time interval between each application of power for opening said sealed pockets.

51. The method of claim 50 wherein said container is provided in an enclosed unit having a holder which is easily accessible from the outside of said unit.

52. The method of claim 51 wherein said holder is in the form of a drawer, pivoting pocket, slot or tray.

53. The method of claim 51 wherein said enclosed unit is an automatic ice making machine.