BACKGROUND

[0001] Aqueous film forming foam (AFFF) compositions are useful for extinguishing a range of fire types including liquid fires and tire fires. AFFF compositions have long relied on fluorine based surfactants. There is an increasing desire to reduce or eliminate the use of fluorine compounds in many applications, including AFFF compositions.

BRIEF DESCRIPTION

[0002] Disclosed is a method of making a fire extinguishing composition comprising: forming a first aqueous solution of potassium acetate, potassium formate or a combination of thereof; forming a second aqueous solution comprising a biocide, a bio- surfactant, and an optional corrosion inhibitor; combining the first aqueous solution with the second aqueous solution to form a third aqueous solution and mixing until the third aqueous solution is transparent; adding a chelating agent to the transparent third aqueous solution and mixing to form a transparent fourth aqueous solution.

[0003] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the potassium acetate may be present in an amount of 1 to 40 weight percent (wt%) based on the total weight of the fourth aqueous solution.

[0004] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the potassium formate may be present in an amount of 1 to 40 weight percent (wt%) based on the total weight of the fourth aqueous solution.

[0005] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the total amount of potassium salts in the fourth solution may be 30 to 55 wt%, based on the total weight of the fourth aqueous solution.

[0006] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the second aqueous solution may be formed by mixing the biocide and bio-surfactant with water.

[0007] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the second aqueous solution may further comprise one or more of butyl carbitol and a dye.

[0008] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the third aqueous solution may be mixed for at least 8 hours at 20-35°C. [0009] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the chelating agent may be an alkyl diamine tetraacetic acid.

[0010] In addition to one or more of the features described above, the fourth aqueous solution may have a pH of 7-8.

[0011] In addition to one or more of the features described above, the fire

extinguishing composition may be free of any fluoro surfactant.

[0012] Also disclosed is a fire extinguishing composition made by the method described above.

[0013] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the composition may have potassium acetate is present in an amount of 1 to 40 weight percent (wt%) based on the total weight of the fourth aqueous solution.

[0014] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the composition may have potassium formate is present in an amount of 1 to 40 weight percent (wt%) based on the total weight of the fourth aqueous solution.

[0015] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the composition may have a total amount of potassium salts in the fourth solution of 30 to 55 wt%, based on the total weight of the fourth aqueous solution.

[0016] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the second aqueous solution may further comprise one or more of butyl carbitol and a dye.

[0017] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the chelating agent may be an alkyl diamine tetraacetic acid.

[0018] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the fourth aqueous solution may have a pH of 7-8.

[0019] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the fire extinguishing composition may be free of any fluorosurfactant. [0020] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the chelating agent may be ethylene diamine tetraacetic acid.

DETAILED DESCRIPTION

[0021] A detailed description of one or more embodiments of the disclosed method and composition are presented herein by way of exemplification and not limitation.

[0022] A method of making a fire extinguishing composition comprises: forming a first aqueous solution of potassium acetate, potassium formate or a combination thereof; forming a second aqueous solution comprising a biocide, a bio-surfactant and an optional corrosion inhibitor; combining the first aqueous solution with the second aqueous solution to form a third aqueous solution and mixing until the third aqueous solution is transparent; adding a chelating agent to the transparent third aqueous solution and mixing to form a transparent fourth aqueous solution.

[0023] Potassium acetate has the formula KCEfiCOO. When present, the potassium acetate may be present in an amount of 1 to 40 weight percent (wt%) based on the total weight of the fourth aqueous solution. Within that range the amount of potassium acetate may be 5 to 30 wt%, or 10 to 20 wt%.

[0024] Potassium formate has the formula KHCOO. When present, the potassium formate may be present in an amount of 1 to 40 wt% based on the total weight of the fourth aqueous solution. Within that range the amount of potassium formate may be 5 to 30 wt%, or 10 to 20 wt%. In some embodiments the amount of potassium formate is less than the amount of potassium acetate. The total amount of potassium salts in the fourth aqueous solution may be 30 to 55 wt%, based on the total weight of the fourth aqueous solution.

[0025] The first aqueous solution may be formed by first dissolving the potassium acetate in water and then adding the potassium formate and stirring until dissolved. The solution may be heated at 30-35°C while stirring. If insoluble impurities are present the solution may be filtered.

[0026] The second aqueous solution may be formed by combining a biocide, a bio surfactant and an optional corrosion inhibitor with water. In some embodiments, the biocide and bio-surfactant are added first and stirred, optionally followed by a corrosion inhibitor.

The second aqueous solution may further comprise one or more of butyl carbitol and a dye.

[0027] An exemplary biocide is Kathon CG/ICP manufactured by Rohm and Hass. Kathon CG/ICP comprises 5-chloro-2-methyl-4 and 2-methyl-4-isothiazolin-3-one in an inert inorganic salt solution of magnesium chloride and magnesium nitrate. The biocide may be used in an amount of 1 to 5wt%, based on the total weight of the fourth aqueous solution.

[0028] Exemplary corrosion inhibitors include MAXHTB OA3090 available from PCC Chemax, sodium tolytriazole and combinations thereof. When present, the corrosion inhibitor may be used in an amount of 0.1 to 5 wt%, based on the total weight of the fourth aqueous solution.

[0029] Exemplary bio-surfactants include non-ionic alkyl glycosides. An exemplary non-ionic alkyl glycoside is APG 325N available from BASF. The non-ionic alkyl glycoside may be used in an amount of 1 to 10 wt%, based on the total weight of the fourth aqueous solution.

[0030] The second aqueous solution is combined with the first aqueous solution, while stirring at 20 to 35°C. Elpon combination of the two aqueous solutions the mixture will become cloudy - indicating a reaction. After stirring for more than 30 minutes, the mixture will become transparent, forming the third aqueous solution. The chelating agent is then added to the transparent third aqueous solution. Upon addition of the chelating agent the mixture will become cloudy and there may be the visual appearance of bubbles - indicating a reaction. The mixture is stirred at 20-35°C for at least 8 hours until the mixture is clear and forms the fourth aqueous solution.

[0031] Exemplary chelating agents include an alkyl diamine tetraacetic acid such as ethylene diamine tetraacetic acid (EDTA). Preferably the alkyl diamine tetraacetic acid is in the acid form. When a salt form of the alkyl diamine tetraacetic acid is used the storage stability of the mixture may be reduced as solids may form over time. The chelating agent may be used in an amount of 1 to 5 wt%, based on the total weight of the fourth aqueous solution.

[0032] The resulting fire extinguishing composition shows excellent foaming behavior and has a pH of 7-8 without the addition of any additional acid. Additionally the composition remains stable at low temperatures such as -20 to -40 °C. The fire extinguishing composition is free of any fluorosurfactant.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms“a”,“an” and“the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or“comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

[0034] While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.