Biocide compositions comprising quaternary ammonium and urea and methods for their use   

The present application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/061,266, filed on Jun. 13, 2008, the disclosure of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present application relates generally to biocide compositions, and more particularly relates to biocide compositions including quaternary ammonium and urea.

BACKGROUND OF THE INVENTION

Biological contamination by pathogens such as bacteria, fungus, algae and viruses may cause significant problems in a variety of products and processes. Unfortunately, the locations and conditions in which biological contamination occurs may create obstacles to treating the contamination. For example, contamination may occur (1) at temperatures at which traditional biocides are unstable; (2) in locations such as crevices, pockets, and pores that are too difficult to reach with traditional biocides; (3) in products such as a food that are not permitted to come in direct contact with traditional biocides; and (4) in the presence of organic matter that may destroy or breakdown the effectiveness of traditional biocides.

It would therefore be desirable to provide biocide compositions and methods of treating pathogens that overcome one or more of these limitations. The compositions and methods may be inexpensive, may require low levels of non-toxic biocide, may be stable and effective at high and low application temperatures, may have enhanced wetting properties, may provide effective treatment over a wide range of pH, and/or may provide effective treatment in a wide variety of products and processes.

SUMMARY

The present application thus provides improved methods for preparing biocide compositions and improved methods for treating and/or preventing biological contamination using a biocide composition comprising at least one quaternary ammonium compound and urea. In accordance with an embodiment of this invention, it has now been discovered that drying urea, and thereafter combining at least one quaternary ammonium compound and urea may produce a potent biocide composition that is stable at high temperature and able to chemically treat biological contamination in a variety of difficult to reach locations. As used herein, stable means the biocide remains effective as a biocide with substantially the same potency as when first made and the biocide components do not substantially separate from one another.

DETAILED DESCRIPTION

The biocide compositions described herein are useful in treating and/or preventing many types of biological contamination. Non-limiting examples of contamination suitable for treating and/or treating include bacteria, fungus, algae and viruses. In an embodiment, the biocide composition may comprise urea and a quaternary ammonium compound. In another embodiment, the biocide composition may comprise urea and a plurality of quaternary ammonium compounds.

Urea has a chemical formula of (NH2)2CO. In an embodiment, the biocide composition comprises urea that is substantially free of impurities. In a particular embodiment, the biocide composition comprises urea that is pharmaceutical grade.

Quaternary ammonium compounds, also known as “quats,” are alkyl dimethyl benzyl ammonium chlorides. Quats have a structure in which a nitrogen atom (N) is covalently bonded to two methyl groups (CH3), one benzyl group (CH2C6H5), and one alkyl chain (R) to form a positively charged cation that may be stabilized by a negatively charged chlorine (Cl) ion. According to an embodiment of the present invention, in a dry form, the biocide composition may be stabilized and non-ionic or neutral due to the association of the quat cation with the chlorine ion. When the biocide composition is diluted in water, the chlorine molecule may detach from the anion.

In a preferred embodiment, the quat has the following structure:

The alkyl chain (R) may have a length in the range of about eight carbons (C8H17) to about eighteen carbons (C18H37). Non-limiting examples of suitable alkyl chains include C8H17, C9H19, C10H21, C11H23, C12H25, C13H27, C14H29, C15H31, C16H33, C17H35, and C18H37. In a particular embodiment, the biocide composition comprises a quaternary ammonium compound in which the alkyl chains have a chain length that is substantially identical in each of the quat molecules. In another embodiment, the biocide composition comprises one or more quaternary ammonium compounds in which the length of the alkyl chain varies between the quat molecules.

In an embodiment of this invention, the quat/urea biocide composition comprises one or more quaternary ammonium compounds in which the alkyl chain has a length in the range of about 12 carbons to about 18 carbons. For example, according to an embodiment, about 50 to about 100% by weight of the one or more quaternary ammonium compounds present in the quat/urea biocide composition have an alkyl chain has a length in the range of about 12 carbons to about 18 carbons. According to another embodiment, about 50 to about 100% by weight of the one or more quaternary ammonium compounds present in the quat/urea biocide composition have an alkyl chain has a length in the range of about 14 carbons to about 16 carbons. Furthermore, according to a certain embodiment, 60% by weight of the one or more quaternary ammonium compounds present in the quat/urea biocide composition have a C16H33 alkyl chain, 30% by weight of the one or more quaternary ammonium compounds present in the quat/urea biocide composition have a C14H29 alkyl chain, 5% by weight of the one or more quaternary ammonium compounds present in the quat/urea biocide composition have a C12H25 alkyl chain, and 5% by weight of the one or more quaternary ammonium compounds present in the quat/urea biocide composition have a C18H37 alkyl chain.

Furthermore, according to certain embodiments of the present invention, the quat/urea biocide composition is substantially dry when made and while stored so that the quat/urea biocide composition remains stable and non-ionic or neutral due to the association of the quat cation with the chlorine ion. Thus, according to certain embodiments of the present invention, the quat/urea biocide composition comprises water in an amount no more than about 3% by weight of the quat/urea biocide composition, or no more than about 2% by weight of the quat/urea biocide composition, or no more than about 1% by weight of the quat/urea biocide composition. As will be explained in more detail below in the description of certain embodiments for making the biocide composition, the one or more quats and urea are dried before they are mixed together and the one or more quats and urea are combined in a manner and in a weight ratio so that the urea and the one or more quats may bind into a single product, the urea may become chelated, and/or the one or more quats may become encapsulated in the urea, the biocide composition may be stabilized and non-ionic or neutral due to the association of the quat cation with the chlorine ion, and the orientation of the biocide at interfaces may be substantially perfect so the biocide composition may impart a substantially reduced surface tension to water when added to water to form an aqueous solution. According to certain embodiments, the one or more quats and urea are present in the biocide composition in amounts based on a weight ratio of the one or more quats to urea from about 10:90 to about 90:10, or from about 20:80 to about 60:40, or from about 30:70 to about 50:50, or a weight ratio of about 40:60.

According to an embodiment of this invention, a method of making the biocide composition may comprise the steps of drying the urea and then combining the one or more quats and the urea to form a biocide composition. According to another embodiment of this invention, a method of making the biocide composition may comprise the steps of drying the one or more quats and urea and then combining the one or more quats and the urea to form a biocide composition. According to an embodiment, the method also may include removing solvent from the combined quat and urea composition and/or granulating the composition.

According to an embodiment, the step of drying the one or more quats and urea may include separately drying the one or more quats and urea. In a particular embodiment, the urea is heated to a temperature in a range from about 80 to about 120° C., or about 90 to about 110° C., or to a temperature of about 100° C., and, separately from the urea, the one or more quats are gradually heated to a temperature of up to about 50° C., or to a temperature from about 30 to about 40° C. Thus, according to an embodiment, the one or more quats may be heated over a period of about 30 to about 120 minutes while gradually increasing the temperature at a rate of about 0.2 to about 1.5° C. per minute. As a result of the gradual heating, the one or more quats may be substantially dried without affected the stability of the quat molecules.

According to a particular embodiment, the drying of quats may take place at a very low level of humidity. Alternatively, if humidity level is above about 10%, the drying treatment may take place after a step of adding organic solvent to the quats. In other words, an organic solvent may be added to the one or more quats before heating the one or more quats. According to particular embodiments, the organic solvent may include an alcohol, glycol, ketone, or combinations thereof. In a particular embodiment, the organic solvent comprises ethylene glycol, acetone, methanol, isopropanol, glycerines or combinations thereof. According to certain embodiments, the ratio of the amount of organic solvent to the amount of quats may be in a range from about 1:2 to about 1:4 by weight or about 1:3 by weight. According to an embodiment, the one or more quats may be dried under a vacuum. Suitable sources of heat for heating the one or more quats may include a variety of sources known to those skilled in the art. According to one embodiment, the urea may be heated by light such as emitted by heating lamps.

According to an embodiment, the step of drying the urea comprises drying the urea until the urea comprises water in an amount no more than 10% by weight of the urea, or no more than 5% by weight of the urea, or no more than 1% by weight of the urea. According to an embodiment, the step of drying the one or more quats comprises drying the one or more quats until the one or more quats comprises water in an amount no more than 3% by weight of the one or more quats, or no more than 0.5% by weight of the one or more quats, no more than 0.2% by weight of the one or more quats.

The step of combining the one or more quats and urea may comprise essentially any method known in the art. In a particular embodiment, the method comprises spraying the one or more quats onto or over the urea and then mixing the one or more quats into the urea. As a result of the high temperatures and low percentage of water in the one or more quats and urea, the quats may be quickly absorbed in the urea to create a paste. In an embodiment of this invention, the one or more quats may be added to the urea gradually while mixing with the urea or by adding one portion of the one or more quats after another to the urea while mixing the quats into the urea after each portion of the one ore more quats is added to the urea. In a certain embodiment, after the one or more quats have been combined with the urea, the composition may be further dried so as to remove any solvents present in the composition. According to a particular embodiment, the one or more quats and urea are mixed substantially homogeneously throughout the biocide composition.

According to a particular embodiment, the method of obtaining the composition may further include granulating the composition. The step of granulating the quat and urea biocide composition may comprise essentially any method known in the art. In a particular embodiment, the biocide composition is granulated by forcing the composition through a screen.

In accordance with a certain embodiment of the present invention, the quat/urea biocide composition may be packaged in a substantially water vapor impermeable packaging so that the biocide composition stays dry and stable until used. Examples of suitable water vapor barrier packaging such as metal foils and polymer laminates are well known. One such embodiment, for example comprises a co-extruded polyolefin and EVOH laminate.

The composition and/or method of obtaining the biocide may have a substantial effect on the properties of the resulting composition. The composition and/or method may cause the urea and the one or more quats to bind into a single product, the urea to become chelated, and/or the one or more quats to become encapsulated in the urea. Although the exact mechanism by which this enhances the composition is unknown, it is believed that the treatment may (1) increase the stability and shelf-life of the biocide; (2) increase the temperature stability of the biocide; (3) increase the pH range in which the biocide is stable; (4) increase the stability of the biocide in the presence of organic matter; (5) increase the ability of the biocide to reduce surface tension in aqueous environments; and/or (6) leave a film on a treated surface for residual biocidal effect. In a particular embodiment, the biocide may be stored in stable condition for up to five years in a dry state or up to one year while dissolved in a liquid.

According to an embodiment, the quat/urea biocide may be added to water to form an aqueous solution. The amount of the quat/urea biocide present in the aqueous solution may vary depending on the intended application, but generally is present in the aqueous solution in an amount from about 0.001 to about 2% by weight of the aqueous solution or about 0.01 to about 2% by weight of the aqueous solution, or about 0.1 to about 2% by weight of the aqueous solution, or about 0.5 to about 1% by weight of the aqueous solution. According to an embodiment, an aqueous solution comprising the quat/urea biocide may have a surface tension which is less than about 90% of the surface tension of water, or less than about 75% that of water, or less than about 60% that of water or less than about 56% that of water. In other words, according to an embodiment, an aqueous solution comprising the quat/urea biocide may have a surface tension less than about 65 dynes/cm2, less than about 54 dynes/cm2, less than about 42 dynes/cm2, or less than about 40 dynes/cm2. According to an embodiment, an aqueous solution of the quat/urea biocide may have a surface tension from about 39 to about 64 dynes/cm2, or from about 39 to about 54 dynes/cm2, or from about 39 to about 42 dynes/cm2.

Table 1 below presents a correlation between concentration of a quat/urea biocide in aqueous solution to surface tension of the solution and between concentration of quats in the aqueous solution to surface tension of the solution. The quat/urea biocide used to generate the data in Table 1 comprised 60% by weight urea and 40% by weight quaternary ammonium compounds in which 60% of the alkyl chains are C14H29, 30% of the alkyl chains are C16H33, 5% of the alkyl chains are C12H25, and 5% of the alkyl chains are C18H37.

TABLE 1 Concentration % by Surface Tension % PPM Quats weight quat/urea biocide Dynes/cm2 of Reduction 0 Water 71.7 0.00 4 0.001 64 10.74 40 0.01 53.5 25.38 400 0.1 42 41.42 2000 0.5 40 44.21 4000 1 39 45.61 8000 2 40.5 43.51

According to embodiments of this invention, the proportions of the one or more quats and the urea in the biocide composition and the drying and mixing parameters of the quat/urea biocide and the amount of quat/urea biocide added to water to form an aqueous solution are balanced such that the surface tension of the aqueous biocide solution is sufficiently less than that of water so that the aqueous biocide solution is very dispersible on surfaces of articles to be treated with the aqueous biocide solution. These factors may vary within the ranges described herein to achieve the desirable balance when quats having different alkyl chain lengths are used.

According to an embodiment, the quat/urea biocide may be stable at pH levels in the range from about 3 to 11 and at temperatures of from about −3° C. to about 100° C., or from about 15° C. to about 100° C., or from about 15° C. to about 80° C., or from about 60° C. to about 80° C.

According to embodiments of this invention, quat/urea compositions may be used to disinfect a variety of articles or environments. The concentration and frequency of application may vary from one application to another. A drawback of quats, however, is that they are not stable in the presence of heat, and even at temperatures below 50° C., tend to break down and lose their biocidal properties.

Thus, according to an embodiment of this invention, a method for treating an area with a biocide comprises applying a quat/urea biocide as described hereinabove to an article or environment. According to a certain embodiment the method of applying the biocide may comprise applying the quat/urea biocide in an aqueous solution such as is described hereinabove. In particular embodiments, the quat/urea biocide is heat resistant and is stable at higher temperatures and, therefore, the method may include applying the quat/urea biocide at application temperatures up to about 100° C., or from about 15° C. to about 100° C., or from about 40° C. to about 100° C., or from about 60° C. to about 100° C., or from about 80° C. to about 100° C. Therefore, according to particular embodiments, the one or more quats are present in the aqueous solution in a concentration in a range of about 0.3 ppm to about 20000 ppm, or about 1 ppm to about 10000 ppm, or about 4 ppm to about 8000 ppm, or about 40 ppm to about 8000 ppm, or about 400 ppm to about 8000 ppm, or about 2000 ppm to about 4000 ppm. According to embodiments of this invention, methods of applying the biocide include but are not limited to immersion, spraying, fogging, drenching, or fumigation with an aqueous solution of the biocide or distributing the biocide in dry particulate form.

Method of Treating Chicken Carcasses with the Biocide Composition

Generally described, chickens may be processed in an automated system while hanging from shackles on a conveyor. In particular, the shackled birds may be stunned, slaughtered, bled, scalded to loosen the feathers, plucked, eviscerated, chilled, and then removed from the conveyor for butchering and packaging.

Unfortunately, the hot scalding may open pores on the skin and loosen the flesh so as to allow pathogens to penetrate the carcass. Furthermore, the chilling may close the pores and tighten the flesh so as to trap the pathogens within the carcass. It therefore would be desirable to provide a method of treating pathogens in chicken carcasses at the high temperatures of the scalding and in the small crevices within the carcass. The methods may be inexpensive, may require low levels of non-toxic biocide, and/or may provide effective treatment of carcasses in the presence of high levels of organic material.

It has now been discovered that the quat/urea biocide compositions of the present application may be used during the processing of chicken carcasses. Due to the method of obtaining the biocide, the biocide may effectively treat pathogens in the presence of high levels of organic contamination, at high temperatures, and/or in a variety of difficult to reach locations. Furthermore, the method of treating the carcasses may remove pathogens from the chickens, prevent spoilage of the chicken carcasses, and extend the shelf life of the processed chicken.

The method may include the step of applying a hot aqueous biocide solution to a chicken carcass, the hot aqueous biocide solution comprising a quat/urea biocide as described hereinabove and scalding water. According to embodiments of this invention, the biocide composition may comprise urea and quaternary ammonium as described above, and the biocide composition may be obtained using the methods described above. According to embodiments, the scalding water may have a temperature from about 40 to about 80° C. Surprisingly, despite that fact that the biocide composition comprises quaternary ammonium, it may remain stable in the hot scalding water. Furthermore, the quat/urea biocide may reduce the surface tension of the hot scalding water as explained hereinabove so as to penetrate the pores and crevices of the chicken carcass.

According to particular embodiments, the quat/urea biocide composition is present in the hot aqueous biocide solution in an amount from about 0.0025 to about 0.3% by weight of the aqueous solution or about 0.01 to about 0.3% by weight of the aqueous solution, or about 0.0625 to about 0.125% by weight of the aqueous solution, or about 0.0125 to about 0.05% by weight of the aqueous solution or in an amount of about 0.025% by weight of the aqueous solution. Therefore, according to particular embodiments, the one or more quats are present in the aqueous solution in a concentration in a range of about 10 ppm to about 1200 ppm, or about 25 ppm to about 500 ppm, or about 50 ppm to about 200 ppm, or in an amount of about 100 ppm.

The application of the hot aqueous biocide solution may clean the carcass and loosen the feathers, and the biocide in the hot biocide aqueous solution may destroy the pathogen on the carcass. The step of applying the hot aqueous biocide solution may comprise spraying or blasting the hot aqueous biocide solution onto the chicken carcass. Alternatively, the step of applying the hot aqueous biocide solution may comprise immersing the chicken carcass into the hot aqueous biocide solution.

In a particular embodiment, the step of applying the hot aqueous biocide solution comprises immersing the chicken carcass into the solution while suspended from a conveyor. The conveyor may move the carcass through the solution, and a pump may move the solution in a direction that is countercurrent to the movement of the carcass.

According to particular embodiments, the temperature of the hot aqueous biocide solution when applied to the chicken carcasses is in a range of about 40° C. to about 80° C., or about 50° C. to about 80° C., or about 60° C. to about 70° C., or is about 65° C. Furthermore, the pH of the mixture may be in a range of about 3 to about 11, and/or hardness of the water may be up to about 850 ppm CaCO3 or up to about 550 ppm CaCO3.

According to a certain embodiment of this invention, a method for disinfecting chicken carcasses comprises applying an aqueous solution of the quat/urea biocide comprising quats in an amount of about 800 ppm to a poultry slaughter plant environment by fogging the environment once or twice per day, applying an aqueous solution of the quat/urea biocide comprising quats in an amount of about 200 ppm to food contact surfaces such as grinders, mixers, blenders, choppers, piping conveyers, tables, workstations, tanks, tubs, barrels, tote boxes, smoke sticks, hooks, and the like, by spraying or immersion, applying an aqueous solution of the quat/urea biocide comprising quats in an amount of about 400 ppm to non-food contact surfaces such as walls, columns, floors, ceiling light fixtures, ducts, sinks, trash barrels, drums, non-processing machinery, and the like, by spraying or immersion, applying an aqueous solution of the quat/urea biocide comprising quats in an amount of about 400 ppm to boots, gloves, uniforms, and the like, by spraying or immersion, scalding chicken carcasses with a hot aqueous solution of the quat/urea biocide at a temperature of about 65° C. comprising quats in an amount of about 15 ppm, washing the chicken carcasses after further the chicken with a hot aqueous solution of the quat/urea biocide at a temperature of about 65° C. comprising quats in an amount of 50 ppm, chilling the poultry carcasses in an aqueous solution of the quat/urea biocide comprising quats in an amount of about 50 ppm, storing the chicken carcasses in cooled rooms disinfected with an aqueous solution of the quat/urea biocide comprising quats in an amount of about 800 ppm, and shipping the disinfected packaged chicken carcasses in transportation vehicles disinfected by an aqueous solution of the quat/urea biocide comprising quats in an amount of about 400 ppm by spraying such vehicles.

Methods of applying the quat/urea biocide to chicken carcasses in chicken slaughter plants according to certain embodiments of the present invention are set forth in Table 2. The application information in Table 2 is for a quat/urea biocide comprising 60% by weight urea and 40% by weight quaternary ammonium compounds in which 60% of the alkyl chains are C14H29, 30% of the alkyl chains are C16H33, 5% of the alkyl chains are C12H25, and 5% of the alkyl chains are C18H37. The quat/urea biocide is mixed with water and applied as an aqueous solution. Concentration means amount of quat/urea biocide in the aqueous solution in grams per liter.

TABLE 2 USE DOSE APPLICATION NOTE Disinfection of areas 2 g/L fogging approximately 8 cc/m3 Disinfection of 1 g/L spray approximately 1 liter equipment and surfaces of solution for 15 square meters Disinfection of boots 1 g/L direct to the water change solution each by immersion third day Disinfection of pre- 1 g/16 liters of water direct application 7,000 to 10,000 birds chillers per 1000 liters Disinfection of chiller 1 g/16 liters of water direct application 7,000 to 10,000 birds per 1000 liters Disinfection of 1/gL spray or direct do not dry hands with worker\'s hands application towels Disinfection of baskets 1 g/L direct application or

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