MX2008009558A - Thickened fluid composition comprising chlorine dioxide - Google Patents

Abstract

This invention relates to a stable composition and method of making a thickened fluid composition comprising chlorine dioxide. The stable composition includes a mixture containing a chlorite, an acid source, and a thickener component. At least one of the chlorite, the acid source and the thickener component is in particulate form. In an embodiment, the mixture may be a unitary solid body wherein chlorine dioxide is generated upon interaction with an aqueous medium, such as water. A free halogen source may also be added to the mixture in some cases.

Description

COMPOSITION OF THICKENED FLUID COMPRISING CHLORINE DIOXIDE FIELD OF THE INVENTION This invention relates to chlorine dioxide compositions. In particular the invention relates to a thickened chlorine dioxide composition and a method for preparing the invention.

BACKGROUND OF THE INVENTION Chlorine dioxide at low concentrations (ie, up to 1,000 ppm) has long been recognized as useful for the treatment of odors and microbes, see US Pat. No. 6,238,643. Its use is particularly advantageous where the microbes and / or organic odorants are thought to be controlled in and around food products, since the chlorine dioxide functions without the formation of undesirable side products such as chloramines or chlorinated organic compounds which can be produced when elemental chlorine is used for the same purpose or similar. For example, if a low concentration of chlorine dioxide gas can be kept in contact with fresh products for several days during shipment from the farm to the local vendor, the deterioration regime of the product may decrease. In addition, the chlorine dioxide gas is also considered generally safe for human contact at low concentrations that are effective for deodorization and most antimicrobial afflictions. Additional uses of chlorine dioxide are exemplified in the patents described herein as well as methods for forming chlorine dioxide. The Patent of E.U.A. No. 2,071,091, describes an improved fungicide and bactericide, and an improved sterilization process using chlorous acid and the salts of chlorous acid. The term "chlorous acid and the salts of chlorous acid" includes aqueous solutions of soluble chlorite salts that have been acidified to an acidic pH. These solutions contain mixtures of chlorine dioxide and chlorite anions with the ratio of chlorine dioxide to chlorite being higher when the pH of the solution is lower. This process requires a relatively high degree of expert user to handle and measure alkali chlorine and acid. The requirement for an acidic pH limits the utility of this process when the pH of the preferred solution is alkaline and the resulting solution is contaminated with sodium chloride and by-products of the acid solution. The Patent of E.U.A. No. 2,071,094, describes deodorizing compositions in the form of partitions comprising a dry mixture of a soluble chlorite, an agent acidifying, a filling of lower solubility. The generation of chlorine dioxide begins as the septum dissolves in the water. This process is suitable for non-expert users, but still requires that the resulting solution be produced at an acidic pH and is still contaminated with the solution byproducts of the reagents. In addition, the low-solubility, inert filler leaves a paste of insoluble residue that is difficult to handle and dispose of. The Patent of E.U.A. No. 4,585,482, discloses a long acting biocidal composition comprising a chlorine dioxide that releases the compound and a hydrolysable organic acid generating polymer. The methods are described for producing encapsulated dry polymer microcapsules containing said compositions and water so that the resulting dry materials release chlorine dioxide gas. The main purpose of the polymer encapsulation film of the '482 Patent is to provide hard free-flowing particles, and to protect them against water loss from the interior of the microcapsule. The suppression of the microcapsules in water could produce a chlorine dioxide solution. In addition to being used to treat odors and microbes, chlorine dioxide can also be used in oral care preparations, nipple disinfectants and wound dressings. The Patents of E.U.A. Nos. 5,944,528, and 6,479,037, discloses a teeth whitening composition that includes a first formulation having a chlorine dioxide precursor and a second formulation having an acidulant capable of generating chlorine dioxide upon contact with the precursor. In a modality, the two formulated portions can be mixed uniformly before placing the complete mixed composition in an ethylene vinyl acetate dental guard commonly manufactured for application to the teeth. Alternatively, one of the first and second formulations can initially be applied to the teeth before application to the remaining formulation. The Patent of E.U.A. No. 4,330,531, describes germicidal immaterial and an applicator for dispensing germicidal compositions containing chlorine dioxide. The Patent of E.U.A. No. 5,200,171, describes a preparation and method for oral health. Patent '171 discloses a stable mouth rinse or dentifrice composition containing stabilized chlorine dioxide and phosphates, the phosphates being present in a range between about 0.02% -3.0%. The stabilized chlorine dioxide is formed using an activation inhibitor, the phosphates, to lower the pH at the time the oral preparation is used in the mouth. The Patent of E.U.A. No. 6,312,670 discloses tooth bleaching compositions having compounds containing hydrogen peroxide and bleaching methods teeth. The composition is capable of being administered by means of a dental guard. The Patent of E.U.A. No. 6,312,408, describes a safe tooth whitener for enamel and method of use. The dental bleach includes a whitening agent and a thickening agent. The whitening agent is usually a peroxide and the thickening agent is polyvinylpyrrolidone. Whitening can take place using a dental guard. The bleach can be placed against a flexible strip that is placed on the teeth that will be bleached. The Patent of E.U.A. No. 6,379,685 discloses aqueous acid chlorite nipple sterilizer with improved emollient that provides shelf life, sanitizing ability and tissue protection. The composition can be mixed using two parts, a simple chlorite solution and an acid. The Patent of E.U.A. No. 5,597,561 discloses adherent disinfectant compositions and methods for use in disinfecting the skin. The disinfectant composition is directed to the prevention of microbial infections and comprises a protic acid, a metal chlorite and a gelling agent which, when combined, provide an effective adherent matrix that acts as a disinfectant barrier to prevent the transmission and spread of microbial infections .

In addition to the uses and methods cited above, the present assignee also developed and patented a method for generating chlorine dioxide. The present assignee manufactures tablets that generate Aspetrol® chlorine dioxide described in the Patents of E.U.A. Nos. 6,699,404 and 6,432,322. Tablets are used in a wide array of applications such as oxidizing compounds to hide odors, deodorize areas, disinfect, treat and / or purify water, etc. These patents describe solid bodies for preparing highly converted solutions of chlorine dioxide when added to water. The solid body comprises a metal chlorite such as sodium chlorite, a source of acid such as sodium bisulfate and optionally a source of free halogen such as the sodium salt of dichloroisocyanuric acid or a hydrate thereof. The Patent of E.U.A. No. 6,238,643, also issued to the present assignee, describes a method for producing an aqueous solution of chlorine dioxide from the reaction of chlorine dioxide generating components. The components that generate chlorine dioxide are a metallic chlorite and an acid forming component that does not react to produce chlorine dioxide in the substantial absence of water. The components that generate chlorine dioxide are arranged in a membrane that is permeable to water and / or water vapor but impermeable to the components that they generate chlorine dioxide contained in it. The membrane containing the components that generate chlorine dioxide is immersed in a liquid so that the chlorine dioxide can generate and pass out through the membrane in the liquid that forms the aqueous solution of chlorine dioxide. The patents cited above describe uses and methods for forming chlorine dioxide solutions. Despite being effective for many different purposes, the non-thickened, current and liquid consistency of many of these solutions limit the potential uses of the solution and often require a concerted effort from a user to ensure the solution is applied in an effective manner. . For example, in teeth whitening applications the majority of professionally monitored domestic tooth whitening compositions act by oxidation. These compositions are dispensed in a customized teeth whitening guard for direct use by a patient. Normally, these guards should be kept in the patient's mouth for a period often greater than about 60 minutes, and some times as long as 8 to 12 hours in order to produce some result. In addition, the limitations for using liquid, non-thickened chlorine dioxide solutions are evident when the solution is used in cleaning, sanitizing or disinfecting a surface or substrate, e.g., medical instruments.

For example, some methods to apply the chlorine dioxide solution to medical instruments require that the instrument be immersed in the solution. This method of application requires that a large amount of the solution be spent in order to be effective on the instrument. The solution can also be used as a sprayer to clean, sanitize or disinfect a substrate or area. However, this method of application also presents the problem where the liquid solution may be bled or introduced into unintended areas and may be ineffective in the desired area. The gaseous chlorine dioxide sprayer or non-thickened liquid may also be less substantial and require the user to perform repeated spraying applications. Problems in the art such as the liquid consistency of the solution and the concerted effort required for the user to apply the solution to a substrate or surface can be overcome by using thickened chlorine dioxide solutions. Thickened mixtures of chlorine dioxide are well known in the art as well as aqueous solutions of chlorine dioxide. Thickened mixtures of chlorine dioxide are produced by adding thickening agents such as clays, polymers, gums, etc. to aqueous solutions of chlorine dioxide to produce the mixtures of thickened aqueous fluids and plastic pseudos. The advantage of the thickened mixtures that They include chlorine dioxide is the best adhesion to vertical surfaces and reduced volatility of chlorine dioxide in relation to the unthreaded chlorine dioxide solution. The volatility of chlorine dioxide is reduced because the transfer of masses of chlorine dioxide from the interior of the thickened mixture to the surface is inhibited. There is a need to generate chlorine dioxide at high concentrations. It has been difficult to produce the generation of such high concentrations of chlorine dioxide. Many methods have been used in the matter to produce different forms of chlorine dioxide. One method for manufacturing a viscous chlorine dioxide mixture has been to produce an aqueous solution thickened with sodium chlorite and a second thickened aqueous acid solution and combine the two thickened solutions in the correct ratio at the time of use. Another method involves producing, at the point of use, an aqueous solution of chlorine dioxide using any of the means known in the art (chlorine dioxide generating equipment, mixing solutions of sodium chlorite and acid, mixing chlorite solutions). of sodium, acid and halogen source, etc.) and then adding one or more thickening agents to the chlorine dioxide solution. However, in all cases, the user is required to measure and mix relatively concentrated sodium chlorite and acid solutions in the field at the point of use, and This requires a relatively high degree of training and experience. A mixture of thickened chlorine dioxide is desired to have the consistency required to remain on a surface or substrate for any time and to be effective thereon without requiring much concerted effort from the user. The present invention provides a stable composition and method for forming a thickened mixture comprising chlorine dioxide at high concentrations. The new composition and method provides a way to combine particulate constituents with an aqueous medium to produce the concentrated viscous chlorine dioxide mixture. This invention provides high-yield, non-thickened mixtures of chlorine dioxide and overcomes the drawbacks of the prior art.

SUMMARY OF THE INVENTION This invention relates to a stable composition for forming chlorine dioxide. The composition includes a mixture containing ingredients that form chlorine dioxide such as chlorite, an acid source, and a thickener component, and optionally water, wherein the ingredients are combined so that they are non-reactive. In an embodiment of at least one of the chlorite, the acid source and the thickener component is a particulate form. In other embodiment of this invention, the composition may be a unitary anhydride body wherein the chlorine dioxide is generated by the interaction with water. Alternatively, one or more components of the mixture may be present in an aqueous medium, such as water, while the components are in a non-reactive state; for example, the reactive components are treated with a stabilizing component to avoid immediate reaction in water.

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a stable chlorine dioxide formation composition and method for forming a thickened fluid composition comprising chlorine dioxide. The present invention departs from the chlorine dioxide forms of the prior art which can be thickened and liquid or gaseous. The prior art forms of chlorine dioxide have limited applications due to their consistency. The consistency of the prior art forms of chlorine dioxide often requires a user to make a concerted effort to ensure that the particular type of chlorine dioxide form is maintained on a intended surface. The thickened chlorine dioxide of the present invention, on the other hand, provides better adhesion to many substrates and surfaces than non-thickened chlorine dioxide solutions. The surfaces verticals are best served by thickened chlorine dioxide provided they are used alone or with some kind of chlorine dioxide support device. The thickened chlorine dioxide may exhibit reduced volatility of chlorine dioxide relative to unthreaded chlorine dioxide solutions. The term "stable", as used herein, is meant to mean that the components used to form chlorine dioxide, i.e., the chlorine dioxide forming ingredients, are not immediately reactive with one another to form chlorine dioxide. In any case the components / ingredients can be combined in any form, such as sequentially and / or simultaneously, while the combination is stable until CIO2 is generated. The term "non-reactive", as used herein, is meant to mean that a component or ingredient as used is not immediately reactive with other components or ingredients present to form chlorine dioxide. The phrase "thickened fluid composition" encompasses compositions that can flow under stress of applied stress and that have an apparent viscosity when flowing which is greater than the viscosity of the corresponding aqueous chlorine dioxide solution of the same concentration. It is understood that this covers the entire spectrum of thickened fluid compositions, including: fluids exhibiting Newtonian flux (wherein the rate of shear rate at shear stress is constant and independent of shear stress), thioxotropic fluids (which require a minimum yield stress to overcome before flow and which also exhibit shear thinning with sustained shear stress), pseudoplastic fluids and plastics ( which require that a minimum yield stress be exceeded prior to flow and that also exhibit shear stress shear with sustained shear stress), pseudoplastic fluids and plastics (which require the minimum yield stress to be exceeded prior to flow), fluid compositions dilantante (which increases in apparent viscosity with increasing shear rate) and other materials that can flow under applied yield stress. The phrase "apparent viscosity" is defined as the ratio of shear stress to shear rate in any group of shear conditions that results in the flow. The apparent viscosity is independent of the shear stress for Newtonian fluids and varies with shear rate for non-Newtonian fluid compositions. The chlorine dioxide-forming composition comprises a mixture containing a metal chlorite, an acid source, a thickener component and optionally a free halogen source, wherein these ingredients are combined inone way so that they are not reactive. In one embodiment, at least one of the chlorite, the acid source, and the thickener component is a solid constituent. The solid constituent includes particles, a unitary solid body or a combination of both. Thus, the mixture can, for example, contain a particulate solid metal chlorite, optionally a source of solid particulate acid, optionally a halogen source free of particulate solid, and optionally one or more particulate solid thickeners. , the mixture is a solid body comprising a metal chlorite, a source of acid and optionally a source of free halogen, with solid particulate thickeners. In yet another embodiment, the mixture may be in the form of particles of a powder (for example by grinding) and mixed in a layer of thickener component thus forming a thickened matrix. The thickened matrix is then disposed on a dental strip which is then adhered to a malleable wax for use on the teeth. The mixture generates a thickened aqueous chlorine dioxide when added to an aqueous medium. The aqueous medium comprises water alone or water with additional components such as an acid source or a source of chlorite anion (but not both together), one or more thickening agents, and a source of free halogen when the aqueous medium does not contain a source of chlorine anions. The term "particulate material" is defined as all solid materials. The particulate materials are interspersed with each other to contact each other in some way. These solid materials include particles that comprise large particles, small particles or a combination of large and small particles. The metal chlorite used in the present invention can generally be any metal chlorite. Preferred metal chlorites are alkali metal chlorites, such as sodium chlorite and potassium chlorite. The alkaline earth metal chlorites can also be used. Examples of alkaline earth metal chlorites include cerium chlorite, calcium chlorite, and magnesium chlorite. The most preferred metal chlorite is sodium chlorite. The acid source may include salts of inorganic acid, salts comprising the anions of strong acids and cations of weak bases, acids that can release protons in solution when contacted with water, organic acids, and mixtures thereof. The acid source in particular applications of the present invention is preferably a particulate solid material that does not substantially react with the metal chlorite during the Dry storage, however, reacts with the chlorite of metals to form chlorine dioxide when in the presence of the aqueous medium. As used herein, the term "acid source" shall mean a solid particulate material that by itself is acidic or produces an acidic environment when in contact with liquid and metal chlorite. The acid source can be soluble in water or substantially insoluble in water. Preferred acid sources are those that produce a pH of less than about 7, more preferably less than about 5. Examples of the preferred water-soluble substantially acid-forming source components include, but are not limited to, soluble solid acids in water, such as boric acid, citric acid, tartaric acid, water-soluble organic acid anhydrides such as maleic anhydride, and water-soluble acid salts such as calcium chloride, magnesium chloride, magnesium nitrate, lithium chloride , magnesium sulfate, aluminum sulfate, sodium acid sulfate (NaHS04), sodium diacid phosphate (NaH2P04), potassium acid sulfate (KHS04), potassium dihydrogen phosphate (KH2P04), and mixtures thereof. The most preferred acid source formation component is sodium acid sulfate (sodium bisulfate). The formation components of water soluble acid source Additional features will be known to those skilled in the art and are included within the scope of the present invention. As used herein, the term "free halogen source" or "halogen free source" means a compound or mixtures of halogen releasing compounds upon reaction with water. As used herein, the term "free halogen" means halogen released by a source of free halogen. In one embodiment the free halogen source is a source of free chlorine and the free halogen is free chlorine. Suitable examples of free halogen source used in the anhydride compositions include dichloro isocyanuric acid and salts thereof such as sodium dichloro isocyanurate and / or the dihydrate thereof (alternatively referred to as the sodium salt of dichloroisocyanuric acid and / or the dihydrate thereof and hereinafter collectively referred to as "NaDCCA"), trichlorocyanuric acid, hypochlorous acid salts such as sodium, potassium, and calcium hypochlorite, bromochlorodimethylhydantoin, dibromodimethylhydantoin, and the like. The preferred source of free halogen is NaDCCA. The chlorine dioxide formation composition is such that when added to liquid water, it will produce a thickened solution of chlorine dioxide and, if a free halogen source, free halogen is present. In one embodiment, if free halogen is present, the concentration of free halogen, in particular free chlorine, in the solution being: (a) less than the concentration of chlorine dioxide in the solution on a weight basis and the ratio of the concentration of chlorine dioxide to the sum of the dioxide concentrations of chlorine and chlorine anion in the solution is at least 09.25: 1 by weight; or (b) equal to or greater than the concentration of chlorine dioxide in the solution on a weight basis and the ratio of the concentration of chlorine dioxide to the sum of the chlorine dioxide and chlorite anion concentrations in the solution is of at least 0.50: 1 by weight. Suitable thickeners for producing mixtures of aqueous thickened and pseudo plastic fluids of chlorine dioxide include clays, polymers, gums, etc. The thickeners can be in the form of particles or they can have the form as an aqueous medium. Examples of polymers include superabsorbent polymers and polyacrylate polymers. Laponite clays, attapulgite clays, bentonite clays are suitable clays and illustrative forms include xanthan gums and guar gums. In this invention, the mixture remains stable for some period of time. The stability is attributed to the maintenance of the anhydrous mixture and / or using stabilizing components.

The stabilizing components that can be used in the present invention to inhibit the premature reaction of the mixture between them are coatings or encapsulation materials disposed on one or more of the particulate constituents of the invention. These stabilizing components are designed to be slowly, and not immediately, soluble. Preferred coatings or encapsulating materials include, for example, oleophilic materials and, more preferably, hydrophobic (water insoluble) polymeric materials. Other non-limiting examples of encapsulation or coating materials that can function as a stabilizing component include gums, resins, waxes and conventional edible mineral oils. Such stabilizing coating materials avoid immediate reactions between the mixture and the aqueous medium. The stabilized components can be activated for immediate reaction by techniques known to those of ordinary skill in the art such as rupture of the components or removal of the stabilizing components to expose the component to an aqueous medium for example, by stirring and heating. The term "hydrophobic" or "insoluble in water" as used herein with respect to organic polymers refers to an organic polymer having a Water solubility less than about one gram per 100 grams of water at 25 ° C. Non-limiting examples of suitable water-insoluble polymers, alone or in combination with one or more other components, used herein include polyvinyl acetate, polyacrylamide, polyvinyl chloride, polystyrene, polyethylene, polyurethane and the like. Non-limiting examples of suitable oleophilic coatings or encapsulating materials include paraffin, mineral oil, edible oils such as peanut oil, coconut oil, palm oil or sunflower oil, oleophilic organic esters such as silomano myristate, or isopropyl palmitate, edible polysiloxanes, and the like. Encapsulating materials containing a mixture of paraffin and waxes are also suitable stabilizing components. The etabilizanate component can stabilize one or more of the components of the mixture. In one example, at least one of the components is aqueous and two others are stabilized. When the solid body form of the anhydride composition is used to produce the chlorine dioxide in water of the present invention, the solid particulate components are collectively arranged in a body, such as a unitary body, and then added to the aqueous medium. . The solid bodies are treated in the Patents of E.U.A. commonly assigned Nos. 6,432,322 and 6,699,404 and are incorporated herein by reference. Therefore, a method for forming the thickened C102 mixture involves combining the solid body with solid particulate thickeners, or thickener components / agents, and then adding both to the water. In the present, C102 is produced by the solid body and the mixture is thickened by the thickening agents to produce the thick mixture of C102. In an alternative method, the thickener can be incorporated directly into the solid body. The solid bodies comprise a metal chlorite such as sodium chlorite, a source of acid such as sodium bisulfate, optionally a source of free halogen such as the sodium salt of dichloroisocyanuric acid or a hydrate thereof, and optionally a thickener. Preferably the solid body contains less than about 1% free by weight weight, which can be converted to 100 degrees centigrade. The solid body is suitable for producing an aqueous chlorine dioxide solution when immersed in water and thick chlorine dioxide when a thickener is incorporated directly into the solid body or added as a separate component from the solid body. However, similar to particulate materials Individuals listed above, not all constituents of the solid body are immediately soluble in water. As used in the prevete, the term "solid body" means a solid form, preferably a porous solid form or a tablet comprising a mixture of inorganic granular particles, wherein the size of the particulate ingredients is substantially smaller than the solid body size. Said solid bodies can be formed by a variety of means known in the art, such as tabletting, partitioning, extrusion, concretion, granulation and the like. The preferred method for forming such solid leathers is by compression, also known as tabletting. For reasons of convenience, hereinafter references to tablets and tablet formation should be understood to represent solid bodies made by any method. To produce the solid bodies, the metal chlorite comprises an alkali metal or alkaline earth metal chlorite, preferably sodium chlorite, and more preferably technical grade chlorite which nominally comprises 80% by weight of sodium chlorite and 20% by weight of salts stabilizers such as sodium hydroxide, sodium carbonate, sodium chloride, sodium nitrate and / or sodium sulfate. Suitable acid sources include inorganic acid salts, such as sodium (sodium bisulfate), potassium acid sulfate, sodium dihydrogen phosphate and potassium dihydrogen phosphate; salts comprising the anions of strong acids and cations of weak bases, such as aluminum chloride, aluminum nitrate, cerium nitrate, and iron sulfate; acids that can liberate protons in solution when contacted with water, for example, a mixture of the ion exchange form of molecular sieve acid ETS-10 (see U.S. Patent No. 4,853,202) and sodium chloride; organic acids, such as citric acid and arturic acid; and mixtures thereof. Preferably, the acid source is a source of inorganic acid, and more preferably is sodium bisulfate. The pore size and pore volume scales required to facilitate the desired degree of conversion of chlorite anion to chlorine dioxide will depend on many factors, e.g., the particular combination of reagents in the tablet, the size of the tablet , the shape of the tablet, the water temperature, the desired degree of conversion of chlorite anion to chlorine dioxide, the desired amount of free halogen to be supplied in the solution, etc. Consequently, it is not thought that there is an optimum range only of pore sizes or volumes of chlorine that will produce an optimum result.

Within the ability of one skilled in the art, the pore size and pore volume of a tablet vary to achieve the desired result with respect to the characteristics of the chlorine dioxide solution. For example, the pore size and pore volume can be varied by varying the particle size of the powder used to prepare the tablet or by varying the compaction force used to form the tablet or by varying the particle size and the compaction force. Larger dust particles will generally reproduce larger pores and more pores in the tablet. The strength of compaction or growth will generally reduce both the size and volume of the pores in the tablet. Tablets of one embodiment of the invention have been observed to rapidly produce a highly converted solution of molecular chlorine dioxide, meaning that the conversion ratio (chlorite anion to chlorine dioxide) is 0.25 or above. Preferably, the conversion ratio is at least 0.50, more preferably at least 0.60, and more preferably at least 0.75. The term "conversion ratio" used herein means the calculated ratio of the concentration of free chlorine dioxide in the product solution to the sum of the free chlorine dioxide plus the concentrations of chlorite ions in the solution of product. In addition, the chlorine dioxide solution is produced rapidly in a safe and controlled manner; and when the concentration of chlorine dioxide thus produced is at normal use levels (approximately from 0.1 to about 1,000 ppm, preferably from about 0.5 to about 200 ppm, by weight) in normal tap water, the solution will not contain substantially free chlorine or other free halogen and will have a generally neutral pH. The term "rapidly produced" as used herein means that the production of total chlorine dioxide is obtained in less than about 8 hours, preferably in less than about 2 hours and even more preferably in less than about 1 hour. The term "no free chlorine or other free halogen" used herein means that the concentration of free chlorine or other free halogen in solution is less than the concentration of chlorine dioxide in said solution, more preferably less than 1/4 the concentration of chlorine dioxide, and more preferably not greater than 1/10 the concentration of chlorine dioxide, on a weight basis. The term "generally neutral pH" used herein means that the pH is higher than that normally required to form substantial concentrations of chlorine dioxide in solution (i.e. pH greater than about 2) and lower than the pH at which the pH is known. chlorine dioxide disproportionate in solution (ie, pH below about 12). Preferably, the pH of the resulting solution is between about 4 and 9 to minimize the potential for corrosion of materials with which the solution comes into contact. More preferably, the pH of the resulting solution should be in the range of about 5-9, and more preferably in the range of about 6-9; ideally the pH will be 7. In certain cases, it may be advantageous to produce chlorine dioxide in a solution that is almost at a higher pH or a pH lower than about pH 7. The solid bodies can be used to supply chlorine dioxide in said solutions without materially changing the pH of the solution when the concentration of chlorine dioxide is at normal usage levels. For example, if a solid body is used to produce chlorine dioxide in a normal laundry detergent solution, it is advantageous for the detergent solution to be at alkaline pH (i.e., > 9) where the detergent works best . The solid body can be used for that purpose. In such cases, however, it is preferred that the pH of the resulting detergent / chlorine dioxide solution be below about 12, as the chlorine dioxide is degraded to a pH greater than about 12.

It is often advantageous that the free halogen concentration of the resulting solution is low, since free halogen can lead to corrosion of materials in which the solution comes in contact and the free halogen can react with organic materials to produce toxic halogenated hydrocarbons . Due to the ability of the solid body to produce highly converted solutions of chlorine dioxide in the absence of a free halogen source, it is possible to use sufficiently low amounts of a free halogen source in the solid body tablet formulation to accelerate the reaction of formation of chlorine dioxide without contributing excessive amounts of free halogen to the resulting solution. In other situations, the presence of a relatively high concentration of free chlorine or other free halogen in solution may be acceptable. In such situations, it is possible to use the solid bodies to produce very highly converted aqueous solutions of chlorine dioxide wherein the ratio of the concentration of chlorine dioxide in solution to the sum of the chlorine dioxide and chlorite anion concentrations is greater than 0.5 on a weight basis. In these cases, the concentration of free chlorine or other free halogen in solution may be equal to or even greater than the concentration of chlorine dioxide in solution on a weight basis.

If desired, the tablets may contain additional optional ingredients, which may be useful, for example, to aid in the tabletting process, to improve the physical or aesthetic characteristics of the tablets produced and to aid in the solubilization of tablets and tablets. / o to produce the chlorine dioxide obtained. Such ingredients include but are not limited to fillers such as attapulgite clay and sodium chloride; the formation of tablet diets and lubricants; stabilizers; colorants; cake antiforming agents; desiccant agents such as calcium chloride and magnesium chloride; pore forming agents such as inorganic swelling clay, e.g., Laponite clay available from Southern Clay Products, Inc., and a frame framework initiator that can react with one or more other constituents in the formulation for produce a porous framework structure of low solubility in which the reactions of chlorine dioxide formation can proceed. Effervescent agents such as sodium bicarbonate can be included in small amounts, e.g., about 1 to about 50% by weight based on solid body weight, but these effervescent agents can reduce the conversion of chlorite anion to dioxide. chlorine accelerating the rupture and dissolution of the tablet.

The two general types of tablet devices are included in the tablet form of the present invention. One type of device comprises tablets that are completely soluble in water, and the preferred formulation of said tablets comprises sodium chlorite of technical grade powder, a source of dry powder acid, preferably sodium bisulfate and a non-reactive thickener. As mentioned before, thickeners can be incorporated directly into the solid body or added as a separate component from the solid body. "Additional dry powdered ingredients such as magnesium chloride can optionally be added to further improve the yield and production rate of chlorine dioxide." The dry powder ingredients are mixed and the resulting powder mixture is compressed into a die of tablets at sufficient strength to produce a substantially intact tablet, typically about 70.3-703 kg / cm.sup.2 The resulting tablets are stable during storage while the tablets are protected from exposure to water (either liquid or vapor) .The tablets produce rapidly A highly converted solution of free chlorine dioxide when immersed in water The second type of device comprises tablets that are not completely soluble in water at a high rate.

These non-completely soluble tablets are designed to have (or produce) a low solubility or slowly soluble framework structure in which the chlorine dioxide formation reactions can proceed to complete substantially prior to the dissolution of the porous structure. Generally the tablets of this second type convert a greater proportion of their chlorite anion precursor chemistry to chlorine dioxide compared to the fully soluble tablets described above. The preferred formulation for this second type of tablet device comprises particulate sodium chlorite powder, particulate sodium bisulfate powder, calcium chloride particulate powder and a non-reactive thickener. A particulate powder clay such as Laponite clay can optionally be added to further improve the yield and production rate of chlorine dioxide. At present, Laponite clay that is optionally incorporated directly into the solid body can not be used as a thickener to form thickened chlorine dioxide solution. When used in tablets, Laponite clay is trapped in the pores of the low solubility or slowly soluble porous structure of the second tablet and is not released into the bulk solution which could allow the clays to aggregate and form a medium viscous Laponite clay can still be used to form the thickened chlorine dioxide solution by adding the clay as a separate component with the solid body to the water. In these second types of tablets, the polymers or gums can also be used as thickeners to form the thickened chlorine dioxide solution. The polymers or gums, unlike the Laponite clay, can be added directly to the tablet of the second type or, alternatively, the gums or polymers can be added as a separate component together with the solid body to the water. As with tablets of the first type, the powdered particulate ingredients are mixed and the resulting powder mixture is compressed in a tablet die at a force sufficient to produce a substantially intact tablet, typically about 70.3-703 kg / cm2. The resulting tablets are stable during storage while the tablets are protected from exposure to water (either liquid or vapor). When immersed in water, the tablets rapidly produce a highly converted solution of free chlorine dioxide. Tablets of this second type generally provide more efficient conversion of chlorite anion to chlorine dioxide compared to tablets of the first type. It is thought that this occurs because the structure of low porous solubility provides a favorable environment for the Chlorine dioxide formation reactions proceed until the reagents are substantially finished. The formation of chlorine dioxide tablets of the second type of device is thought to occur substantially within the favorable environment of the pore space of the pore structure of low solubility (or slowly soluble) and is thickened simultaneously with the thickeners. Since the favorable pore structure of this framework appears to remain substantially intact during this reaction time, substantially all of the chlorite anion has an opportunity to react and form chlorine dioxide under favorable conditions within the pores. This increases the conversion of chlorite to chlorine dioxide. In contrast, a device of the first type dissolves in the bulky solution at the same time that chlorine dioxide is produced. Since it is thought that reactants will only react to a practically useful regime under concentrated conditions (such as those existing within the pores of the tablets), the fraction of the corito that dissolves in the bulky solution before the conversion to dioxide chlorine will remain substantially like chlorite and not be converted to chlorine dioxide under the generally dilute conditions of the bulky solution. The porous structure of low solubility of the preferred composition of the second type of device tablet comprises a structure initiator such as a compound of low solubility such as calcium sulfate, calcium phosphate, aluminum phosphate, magnesium phosphate, ferric sulfate, ferric phosphate or zinc phosphate; or an amorphous material of low solubility such as silica-alumina gel, silica-magnesium gel, silica-zirconia gel, or silica gel; and additionally may include a clay or other substantially insoluble structure or pore initiator such as Laponite clay. Calcium sulfate is preferably formed from the reaction between calcium cations e.g., calcium chloride constituent and sulfate anions derived from sodium bisulfate constituent. Other sources of calcium cations such as calcium nitrate can be used as well as other sources of sulfate anions such as magnesium sulfate. Preferably, phosphate anion is provided by the use of soluble phosphate compounds such as sodium phosphate, sodium acid phosphate, sodium diacid phosphate, the corresponding potassium phosphate salts, as well as other soluble phosphate salts. Preferably the silica alumina gel is formed from the reaction between sodium silicate and aluminum sulfate. Preferably, silica-magnesium gel is formed from the reaction between sodium silicate and magnesium sulfate. Preferably, silica-zirconia gel is formed from the reaction between sodium silicate and zirconyl sulfate. He Silica gel is preferably formed from the reaction between sodium silicate and the acidity of the solid acid source. The additional solid acid component may be required to compensate for the alkalinity of the sodium silicate constituent. The preferred clay, Laponite clay, is insoluble as supplied and is not released into the bulky solution. A swelling clay is trapped within the pores and increases the pore structure of the porous structure forming cracks and cavities as it swells. As previously stated, the Laponite clay is trapped in the low soluble or slowly soluble porous frame structure of the second tablet and therefore does not leak into the surrounding water to form a viscous medium. We have found that the formation of the porous structure of low solubility, eg, calcium sulfate, calcium phosphate, aluminum phosphate, etc., structures in situ via chemical reaction is particularly advantageous and that the yield of dioxide chlorine of the tablets wherein the structure formed in situ is significantly better (nominally 25% better) than the tablets in which the structure material constitutes the initial powder formulation. The presence of the clay in addition to the structure material provides only a small improvement over the use of the structure material, without the clay.

The term "porous structure of low solubility or slowly soluble" used herein means a porous solid structure that remains substantially undissolved in the product solution during the period of production of chlorine dioxide. It is not necessary for the porous structure to remain completely intact during the reaction time to form chlorine dioxide. One aspect of this invention includes tablets of the second type in which the tablet disintegrates into substantially insoluble (or slowly soluble) granules that release chlorine dioxide in solution. This is acceptable, it is thought, because the size of the granules is still large relative to the size of the pores within the pore space of the granules, so that the necessary concentrated reaction conditions exist within the space of the pores despite the decomposition of the structure into granules. Normally, the structure initiator will be present in an amount of about 10 to about 90% by weight, based on the weight of the solid body. In high-type tablet devices, it is preferred that the powdered ingredients are dried before mixing and tabletting in order to minimize the chemical interaction between the tablet ingredients.

General Procedures for Forming and Testing the Tablets of the Invention Tablet Formation: The individual chemical components of the tablet formulation are dried before use. The desired amount of each component is carefully weighed in a plastic bottle. In the following examples, the formulations are given on a weight percent basis. The bottle containing all the components of the tablet formulation is stirred to uniformly mix the components. The contents of the bottle are emptied into a die of approximate size (e.g., a diameter of 13 mm for a tablet of 1 g). The plug is placed in the die and the contents are pressed into a pellet using a hydraulic laboratory press. The maximum force read on the press gauge was 907.18 kg unless otherwise noted. This force in the tablet punch can be converted to 0.07 kg / cm2, if the area of the cap face is in era2 (usually 1329 cm2 for a 1 g tablet). The resulting tablet is removed from the die and placed in a closed plastic bottle until it is used (usually within 10 minutes). Tablet Performance: The tablet is placed in a volumetric flask or container filled with a known amount of water current. The evolution of chlorine dioxide starts immediately as evidenced by bubbles and the appearance of a yellow color. The tablet was allowed to react until it was complete. The term of the reaction depends, in part, on the type and size of the tablet. Normally the reaction time is 2 hours or less if 1 g of tablet is partially insoluble and 0.5 hr if a 1 g tablet is completely soluble. When the reaction is complete, the flask / container is agitated in order to mix the contents. Then the content is analyzed. Normally, chlorine dioxide is measured by UV-Vis spectrometry, using four wavelengths (the average value is reported.) Chlorite and chlorine are usually measured by titration of 25 ml of chlorine dioxide solution using equivalent procedures those found in the text, Standard Methods for the Examination of Water and Wastewater, 19th Edition, 81995) pages 4-57 and 4-58 This text was published jointly by the American Public Health Association, The American Water Works Association and Water Environment Federation The publication office is American Public Health Association, Washington, DC 200005. Total oxidotes are measured by titration using the Brinkmann Autotitration System, 716 DMS Titrino equipped with a massive platinum electrode (Brinkmann Part No. 6.0415.100). method is a iodometric titration in an acid medium based on the oxidation of iodine to iodine and its subsequent reaction with the titrant, sodium thiosulfate. The normal procedure was as follows. One hundred milliliters of chlorine dioxide solution and a stir bar were placed on a stirrer and 2 g of potassium iodide (Reagent Crystals) and 10 ml of a 1N solution of sulfuric acid (Mallinckrodt) were added with stirring. The resulting solution was titrated with 0.1N thiosulfate solution (Aldrich Chemical Co.). The end point was determined automatically by the Brinkmann Titrino software. That end point is used to calculate the concentration of total oxidants in the sample. The pH of the original chlorine dioxide solution was measured using a pH electrode either in the "as-is" solution and / or diluted with sufficient water to give approximately a concentration of 10 ppm of chlorine dioxide. Another method for producing thickened mixtures having a high concentration of CIO2 (> 10 ppm), includes providing as the particulate solid particulate solid sodium chlorite and particulate solid thickener and then combining the particles with an aqueous solution. Acid that has enough acidity in excess. The pH of the resulting mixture is < 4 subsequent to the addition of the particulate constituent. Still another alternative may comprise a source of solid acid in particles such as constituent in particles and a sodium chlorite solution containing one or more thickening agents as the aqueous medium. The pH of the resulting mixture after mixing the particulate material is < 4. Other variations are also within the scope of this invention. The thickened fluid composition comprising chlorine dioxide can be made instantaneously by combining the mixture with the aqueous medium. Alternatively, the mixture and the aqueous medium can be retained in a dispensing unit before use and allows the two constituents to combine when dispensed. The dispensing unit may comprise a single housing unit having a separator or divider integrated with the housing to the mixture and the aqueous medium only meets after being dispensed from the dispensing unit. Alternatively, the dispensing unit may comprise a single housing unit having a frangible separator or splitter which initially separates the mixture and the aqueous medium but which allows the mixture and the aqueous medium to mix when the frangible splitter is made to penetrate. Yet another variation in the dispensing unit involves a dispensing unit containing at least two individual frangible containers, one for the mixture of constituents and the other for the aqueous medium; the individual frangible containers are broken by the application of pressure. These and other dispensing units are fully described in the U.S. Patent. No. 4,330,531 and are incorporated herein by reference. Chlorine dioxide has stabilized uses for bleaching textiles and pulp to make paper, deodorizing, disinfecting, sanitizing and sterilizing surfaces or spaces. The present invention can furthermore be used in wound dressings, environmental cleansing, dental / oral care substances, germicidal material, tooth bleaching compositions, and personal lubricants among a variety of other applications. Other uses include oxidizing compounds that hide odor, treat cooling towers, water for emergency drinking, recycled water for car washes, water softeners as well as animal confinement facilities; and non-porous food contact surfaces and utensils. The present invention can also be used in typical industrial applications such as food processing plants, breweries, and food handling establishments, recirculating cooling water systems and in general water treatment facilities. When the composition is used as a therapeutic membrane such as wound dressings it may further include a polymerizable fluid composition comprised of polymerizable organic compounds and photoinitiators. The Patent of E.U.A. 5,597,561 describes an example of a thickened wound dressing. The '561 patent is directed to an adherent disinfectant composition that includes metal chlorites and other ingredients in the composition. The composition '561 provides an effective adherent matrix that acts as a disinfectant barrier to prevent the transmission and spread of microbial infections. When the composition is used in teeth whitening compositions, the composition can be arranged in a dental guard where the composition can be placed against the surface of the teeth via the guard. The composition remains in contact with the tooth surface for a predetermined time. The dental surface is bleached through the oxidative action of chlorine dioxide on chromophores trapped within the acquired thin membrane, enamel and tooth dentin structures. Although not required, the teeth whitening composition may select flavors and sweeteners incorporated in the composition. Alternatively, the composition can be used in tooth whitening compositions via a dental strip or monolithic cover. The cover is a matrix comprised of particulate chlorine dioxide formation components arranged in a thickener such as a super-absorbent polymer. The matrix or cover can configured in the form of a strip so that it can be handled and applied directly to the teeth or adhere to a strip of malleable wax or other sheet material for application on the teeth. The mixture of thickened chlorine dioxide is formed on the cover upon contact with water or other aqueous medium. In order to demonstrate the invention, some examples are shown below.

Example 1 A 250 mg tablet of the composition described in Example 5 of US Patent. No. 6,699,404, was combined with 0.3 grams of ASAP 2000, a super absorbent polymer powder of sodium acrylate supplied by Chemical Corporation of Palatine, Illinois. The above mixture was combined with 20 ml of tap water in a gently stirred transparent glass jar and stored overnight to produce a thick aqueous mixture comprising chlorine dioxide (C102). The mixture was a thickened fluid composition. See Table 1.

Example 2 The procedure of Example 1 was repeated with 0.4 grams of ASAP 2000 acrylate powder. The mixture was a thickened fluid composition. See Table 1.

Example 3 The procedure of Example 1 was repeated with 0.5 grams of ASAP 2000 acrylate powder. The mixture was a thick plastic composition that flowed when inverted. See Table 1.

Example 4 The procedure of Example 1 was repeated with 0.6 grams acrylate powder ASAP 2000. The mixture was a thickened, plastic composition, which flowed when inverted. See Table 1.

Example 5 The procedure of Example 1 was repeated with 0.7 grams of ASAP 2000 acrylate powder. The mixture was a thick plastic composition that flowed when inverted. See Table 1.

Table 1 Table 1 indicates the grams of ASAP used in each example and indicates the consistency of the resulting mixture for Examples 1-5. Table 1 shows that the amount of ASAP refers to the thickened consistency of the mixture.

Example 6 A 250 mg tablet of the composition described in Example 5 of the U.S. Patent. No. 6, 699, 404, was immersed in 20 ml of tap water in a clear glass jar and allowed to react without agitation until dissolved. The solution was then divided into two equal pairs and 3.5 grams of acrylate powder of ASAP 2000 was added to one of the portions (with stirring). Each portion was diluted with 100 ml using tap water. The non-thickened portion was analyzed for C102 concentration by UV / visible spectroscopy using a Spectral Instruments Model 440 UV / visible spectrometer with a direct insertion probe. Both diluted solutions were analyzed for free oxidant concentration by titration of KI / thiosulfate regulated at a pH of 7. The results showed that the non-thickened solution contained approximately 900 ppm C102 (902 ppm C102 by UV / visible spectroscopy and 875 by titration ). The thickened mixture contained 821 ppm of C102 per titration. Based on this result it was concluded that C102 can be stable in a thickened aqueous mixture comprising an organic thickening agent.

Example 7 The Test of Example 6 was repeated and the non-thickened solution contained 1100 ppm CIO2 (1170 ppm per UV / visible spectroscopy and 1062 ppm per titration = .The thickened mixture contained 991 ppm C102 per titration.) Based on this result it was concluded that C102 could be stable in a thickened aqueous mixture comprising an organic thickener.

Example 8 Ten tablets of the composition described in Example 5 of US Pat. No. 6,699,404, were dissolved in 200 ml of tap water to produce a chlorine dioxide solution. To each of seven transparent glass jars added 0.7 grams of ASAP 2000 acrylate powder followed by 20 ml of C102 solution prepared before. Each bottle was gently shaken until a gel formed. The concentration of C102 from a vial was measured immediately by titration and found to be 766 ppm. The rest were hermetically sealed and stored in the dark at room temperature and humidity. At selected time intervals a bottle will be removed from storage and analyzed to determine residual C102 concentration. See Table 2 below.

Table 2 This surprisingly demonstrates the good stability of C102 in the thick mixture. About 25% of C102 was lost from the solution within a week, and the concentration was then substantially discharged.

Example 9 The thick chlorine dioxide provides a way to give controlled release of chlorine dioxide in air. The chemical stability of chlorine dioxide in thick mixtures can be affected by the type of thickener used in the composition. Some thickeners reduce the chemical stability of chlorine dioxide. The chemical stability of chlorine dioxide in thickened mixtures was measured using different thickeners including laponite clay, xanthan gum, guar gum, and brand polyethylene oxide.

Polyox ™. Chemical stability was tested at 0.1% and 1% by weight of thickener concentrations. Table 3 below indicates the retention of chlorine dioxide concentration of the thick chlorine dioxide solution (%) after twenty minutes.

Table 3 The data shows that chlorine dioxide is more stable in some thickeners than others. Here, the twenty-minute mark, the concentration of chlorine dioxide was weakened by 0.1% and 1% by weight concentrations of guar gum, and higher by 0.1% and 1% by weight concentrations of Laponite clay.

Claims (10)

1. - A stable composition for generating a chlorine dioxide containing a thick fluid comprising: a mixture containing a chlorite, an acid source and a thickener component, wherein the components are combined in a non-reactive manner wherein the mixture is Use to generate chlorine dioxide in water.

2. The composition of claim 1, wherein said components are dry solid particulate materials.

3. The composition of claim 1, wherein the mixture comprises a unitary solid body comprising at least two of chlorite, the acid source or the thickening components.

4. The composition of claim 3, wherein the solid body comprises a metal chlorite, an acid source, optionally a thickening component, and optionally a source of free halogen.

5. The composition of claim 3, wherein the solid body comprises a metal chlorite, an acid source, a non-reactive thickener component, and optionally a source of free halogen.

6. The composition of claim 1, wherein the mixture is a combination of thickener components in particles and a unitary solid body comprising the chlorite and the acid source.

7. The composition of claim 1, wherein at least one of the chlorite of the acid source is an aqueous medium and at least one of said chlorite from the acid source was treated with a stabilizing component.

8. - The composition of claim 1, wherein the metal chlorite and the acid source and in a solid matrix comprising the thickener component.

9. A method for forming a thick chlorine dioxide fluid composition comprising the steps of: preparing a solid constituent containing at least one receipt that forms chlorine dioxide in water; provide a thickener component; and combining said solid constituent with said thickener component in water wherein at least a portion of the solid constituent is not immediately soluble in water and wherein said at least one reagent reacts with a second reagent to form chlorine dioxide.

10. The method of claim 9, wherein the thickener component is a particulate material and the solid constituent is a solid body comprising a mixture of metal chlorite, a source of acid, and optionally a source of free halogen.