Background of the Invention Fire extinguishing foams of various types, typically formed from concentrates, are known for use against fires of polar and non-polar flammable liquids such as hydrocarbon solvents, gasoline, kerosene, crude oil, and the like.

Often these foams additionally provide the ability to form a film on the surface of a liquid. Such a film not only helps to extinguish the fire but can inhibit re-ignition of the flammable liquid once the fire has been extinguished by the foam.

Aqueous film forming foam (AFFF) concentrates are concentrated aqueous solutions that can be diluted and used to extinguish flammable liquids (i. e., Class B) fires. These concentrates can contain fluorinated surfactants, fluorine-free surfactants, foam stabilizers, and other various additives. Based on industrial convention, these concentrates are generally designated as 1%, 3%, or 6% concentrates. The significance of this numerical designation is that the concentrate can be formed into a fire-fighting premix composition by diluting the designated parts by volume concentrate (i. e., 1,3, or 6) with sufficient water such that the parts water plus the parts concentrate will equal 100. For example, 3 parts by volume of a 3% concentrate is diluted with 97 parts of fresh or sea water to form a premix. In practice water is typically delivered through a fire hose and from 1 to 6 parts by volume of the premix are inducted by venturi effect into 94 to 99 parts of water, to form a premix. The premix is then converted into a foam by use of an air-aspirating nozzle located at the outlet of the fire hose. The resulting thick,

mobile foam blanket achieves rapid knockdown, control, extinguishment and resistance to reignition of the flammable liquid. A vapor-sealing film drains from the foam to rapidly spread over the flammable fuel surface, acting as a barrier between the fuel surface and the oxygen-containing air.

Amine oxide surfactants having a fluorocarbon moiety are generally known in the art. British Patent Specification 1,302,612 discloses amine oxides of the general formula: (Rf) lQmCnR2nN (R') 2->0 wherein Rf is a saturated fluorinated non-aromatic radical in which the carbon atoms are substituted only by fluorine, chlorine or hydrogen atoms with no more than one hydrogen or chlorine atom for every two adjacent carbon atoms. The use of such fluorocarbon surfactants in fire-fighting compositions is discussed.

U. S. Pat. No. 3,772,195 (Francen) describes an aqueous concentrate composition useful for suppressing vaporization of a liquid hydrocarbon comprising (a) a film-forming component comprising a water soluble fluorinated surfactant; (b) a synthetic, imputrescible, hydrocarbon-congruous, water soluble, organic, fluorine-free surfactant; (c) a water-soluble stabilizer selected from the group consisting of alkyl ethers of alkylene glycol and glycerol; and (d) up to 95 weight percent water.

U. S. Pat. No. 4,983,769 (Bertocchio) discloses fire-fighting compositions containing a perfluoroalkyl amine oxide of the formula: CnF2n+l (CH2) aso2N (Rl) (CH2) pN (CH3) 2-->O wherein CnF2n+l is a straight or branched perfluorinated chain, n is a whole number from 1 to 20, a is a whole number from 2 to 10, RI is either a hydrogen atom or an alkyl group, and p is a whole number from 2 to 10.

Cleanup and disposal of fluorinated surfactants in AFFF agents is becoming an increasingly important issue in view of the resistance of the

fluorocarbon backbone to undergo chemical or biological degradation. The ability to remove such agents from the environment in an efficient manner will help to prevent the possibility of contamination of the soil or ground water with these agents, allowing stringent environmental safety standards to be maintained.

A need exists in the art for effective foamable fire-fighting compositions that have desirable properties with respect to storage stability, foaming and spreading qualities, burnback, and the like, and that can be removed from the environment after being used to extinguish a fire.

Summary of the Invention The invention provides a fire-fighting composition made up of : (a) a compound of the formula (I) wherein Q is SO, or CO; RI is H; C, 6alkyl or C, 6alkyl substituted by halogen, OH, SH, C, 6 alkoxy, C, 6 alkylthio, NO,, CN or NRR'wherein R and R'are independently H or C, 6 alkyl; R2 and R3 are independently C, 6alkyl; C, 6alkyl substituted by halogen, OH, SH, C-6 alkoxy, Cl 6alkylthio, NO2, CN or NRR'wherein R and R'are independently H or C1-6 alkyl ; or R2 and R3 may join to form a 5 to 7 membered heterocyclic ring that may contain one or more additional hetero atoms and that may be substituted by one or more C, 6 alkyl groups; n is 2 to 6; and Rf is a substantially fluorinated C8, 8 alkyl group; (b) an effective amount of fluorine-free surfactant; (c) an effective amount of organic solvent; and (d) water.

In addition the invention provides fire-fighting compositions made up of: (a) a compound of the formula (II):

wherein Q is SO, or CO; R4 is H; C, 6 alkyl or C, 6 alkyl substituted by halogen, OH, SH, C, 6 alkoxy, C, 6 alkylthio, NO,, CN or NRR'wherein R and R'are independently H or C, 6 alkyl; R5 and R6 are independently C1-6 alkyl ; C, 6 alkyl substituted by halogen, OH, SH, C1-6 alkoxy, C1-6 alkylthio, NO2, CN or NRR'wherein R and R'are independently H or C, 6 alkyl; or R5 and R6 may join to form a 5 to 7 membered heterocyclic ring that may contain one or more additional hetero atoms and that may be substituted by one or more C, 6 alkyl groups; n is 2 to 6; and Rf is a substantially fluorinated C, 0 20 cycloalkyl, or a C8, 8 alkyl interrupted by one or more-O-or-S-atoms; (b) an effective amount of fluorine-free surfactant; (c) an effective amount of organic solvent; and (d) water.

A concentrate of the fire-fighting composition preferably contains from about 0.5 to 12 wt-% of one or more compounds of formulas (I) or (II). This concentrate composition can be diluted with salt or fresh water, typically 1,3, or 6 parts by volume of the fire-fighting concentrate per 99,97, or 94 parts water, respectively, to form a premix composition that preferably contains from about 0.01 to 0.12 wt-%, more preferably from about 0.03 to 0.10 wt-% of one or more of the compounds of formulas (I) or (II).

The invention further provides methods of fighting fires by diluting with water, aerating, and applying to the surface of a liquid fire, an effective amount of a fire-fighting composition as described above.

Fluorinated amine oxide surfactants useful in the fire fighting compositions of this invention adsorb strongly from an aqueous solution onto materials commonly encountered in the ground, for instance nutrient sludge, various types of soil, sand, clay, bacteria surfaces, and the like. This adsorption is so strong that in some cases virtually no fluorinated surfactant can be detected in the water that remains after use, as measured indirectly by surface tension reduction or directly by chromatographic or by fluorine analysis. Thus, nearly quantitative removal of the fluorinated amine oxide surfactants from the environment can be accomplished, potentially preventing the fluorinated surfactant from contacting subsurface groundwater, greatly reducing groundwater contamination and foaming problems.

As used herein, the term"alkyl"includes both straight-chain and branched alkyl groups of all sizes. Examples of such alkyl groups include straight chain groups such as methyl, ethyl, n-propyl n-octyl, n-nonyl etc., as well as branched groups such as i-propyl, sec-butyl, i-butyl, tert-butyl, iso-octyl, t-octyl, n- decyl, etc. When the alkyl group is interrupted by one or more-O-or-S-atoms, this interruption can take place in a branch or at a branching point, as well as in the long chain of the alkyl group. This definition applies both to fluorinated and non- fluorinated alkyl groups.

The term"substantially fluorinated,"as in a substantially fluorinated hydrocarbon moiety indicates that at least about 75 percent, preferably at least about 85 percent, more preferably at least about 95 percent of the hydrogen atoms of the hydrocarbon moiety are replaced by fluorine atoms. Optionally, remaining hydrogen atoms can be replaced by other halogen atoms, such as by chlorine atoms.

Detailed Description The fluorinated amine oxide surfactants useful in the fire-fighting compositions of the invention have formulas (I) and (II): wherein Q is SO2 or CO; RI is H; C, 6alkyl or C, 6alkyl substituted by halogen, OH, SH, Cl 6 alkoxy, C, 6 alkylthio, NO,, CN or NRR'wherein R and R'are independently H or C1-6 alkyl ; R2 and R3 are independently C, 6 alkyl; C, 6 alkyl substituted by halogen, OH, SH, Cl 6 alkoxy, C, 6 alkylthio, NO2, CN or NRR'wherein R and R'are independently H or C1-6 alkyl ; or R2 and R3 may join to form a 5 to 7 membered heterocyclic ring that may contain one or more additional hetero atoms and that may be substituted by one or more C, 6 alkyl groups; n is 2 to 6; and Rf is a substantially fluorinated C8-18 alkyl group; wherein Q is SO2 or CO; R4 is H; Cl 6 alkyl or C, 6 alkyl substituted by halogen, OH, SH, C1-6 alkoxy, C1-6 alkylthio, NO2, CN or NRR'wherein R and R'are independently H or C, 6 alkyl; R5 and R6 are independently Cl 6 alkyl; C,. 6 alkyl substituted by halogen, OH, SH, C1-6 alkoxy, C1-6 alkylthio, NO2, CN or NRR'wherein R and R'are independently

H or Cj. g alkyi; or R5 and R6 may join to form a 5 to 7 membered heterocyclic ring that may contain one or more additional hetero atoms and that may be substituted by one or more C, 6 alkyl groups; n is 2 to 6; and <BR> <BR> Rf is a substantially fluorinated C, cycloalkyi, or C8 8alkyl interrupted by one or more-O-or-S-atoms. Preferably, Rf is fully fluorinated.

When R2 and R3 or R5 and R6 join to form a heterocyclic ring, that ring may be saturated or unsaturated and may contain one or more additional hetero atoms in the ring, such as O, S, or N. Examples of suitable heterocyclic rings include morpholine, thiomorpholine, piperidine, piperazine, pyridine, 1,2- diazine, 1,3-diazine, 1,4-diazine, pyrrole, pyrrolidine, imidazole, pyrazole, thiazole, isothiazole, oxazole, isoxazole, triazole, tetrazole, and the like. These rings may be unsubstituted or substituted by one or more C, 6 alkyl groups.

The fluorinated amine oxide surfactants useful in the invention may be prepared by treating an alcoholic solution of the appropriate fluorinated carboxamidoamine or sulfonamidoamine precursor with hydrogen peroxide. This reaction may be carried out at elevated temperatures, for example at about 60° to 70°C. After reaction, excess hydrogen peroxide may be decomposed with activated carbon, palladium/carbon or manganese dioxide, followed by filtering to remove the unconsumed solids.

The fluorinated carboxamido-or sulfonamido-amine precursor may be commercially available or may be prepared by reaction of the appropriate perfluorinated sulfonyl or carbonyl fluoride with a diamine that contains both a primary nitrogen and a tertiary nitrogen in the presence of an acid scavenging tertiary amine such as triethylamine. The reaction is preferably carried out in an organic solvent such as an aromatic or aliphatic hydrocarbon or ether solvent.

Examples of appropriate solvents include toluene, heptane, isopropyl ether, tetrahydrofuran and the like. The solvent is removed before the precursor is reacted to form the amine oxide surfactant used in the invention.

The fluorinated amine oxide can be present in the fire-fighting composition of the present invention in any amount that will provide a composition

capable of effectively extinguishing and securing a flammable liquid fire (e. g., in the case of a premix composition) or, in the case of a concentrate composition, the amine oxide can be present in an amount that when diluted and foamed, will provide such a fire-fighting composition. Preferably, the fire-fighting concentrate compositions of the invention contains from about 0.5 to 12 wt-% fluorinated amine oxide surfactant, based on the total weight of the concentrate. The amount of fluorinated amine oxide surfactant in a concentrate composition will of course depend on the designated concentration of the concentrate (i. e., whether it is a 1,3, or 6% concentrate). As an example, a 1% concentrate can preferably contain from about 3 to 12 wt-% fluorinated amine oxide surfactant. Also preferably, the premix composition (the diluted concentrate) contains from about 0.01 to 0.12 wt-%, more preferably from about 0.03 to 0.1 wt-% fluorinated amine oxide surfactant, based on the total weight of the premix composition.

When the sulfonamide nitrogen of the fluorinated amine oxide surfactant is substituted by hydrogen the surfactant can exist in one of several ionic forms. These different forms are illustrated by formulas (III), (IV) and (V) below: (Protonated Foam) (metal salt form)

wherein M is an alkali metal or alkaline earth metal, preferably Na or K. Although illustrative formulas (III), (IV) and (V) as shown are based on the structure of formula (I), similar salt forms of the fluorinated amine oxide can exist for compounds of formula (II) as well.

The amount of each ionic form of the fluorinated amine oxide surfactant found in an aqueous composition varies with the pH of the composition.

At a pH of about 4.6 or below, there is essentially no metal salt formation. The amount of salt increases to about 50% at a pH of about 6.5, and at a pH of 9.3 or above the fluorinated amine oxide surfactant exists almost entirely in the salt form.

At the preferred pH of about 8, the surfactant is about 70% in the salt form.

The compositions of the invention also include an effective amount of a fluorine-free surfactant. These surfactants may be nonionic, anionic, amphoteric, or a mixture of these types, with amphoteric and anionic surfactants being generally preferred. In general, fluorine-free surfactants useful in the inventive compositions have a hydrophilic/lipophilic balance (HLB) greater than or equal to about 10.

Non-fluorinated surfactants (particularly hydrocarbon surfactants) can be added to the fire-fighting compositions of the present invention for a number of reasons. For example, the presence of non-fluorinated hydrocarbon surfactant is desired to make clear, stable sea water premixes, because in the absence of non-fluorinated surfactants, sea water premixes tend to foam poorly and can precipitate or phase out the fluorinated surfactant.

Useful nonionic fluorine-free surfactants include ethylene oxide- based nonionic surfactants, for example ethoxylated alcohols such as CkH2k+lO (C2H40) mH wherein k is an integer between about 8 and 18 and m is greater than or equal to about 10; ethoxylated alkylphenols such as

wherein p is an integer between about 4 and 12 and m is greater than or equal to about 10 (e. g., TritonTM X-305, a 30-mole ethoxylate of a branched chain octylphenol, commercially available from Union Carbide Corp., Danbury, Connecticut); and block copolymers of ethylene oxide and propylene oxide (e. g., Pluronic F-77 surfactant, which contains about 30% by weight of polymerized ethylene oxide, commercially available from BASF Corp., Parsippany, New Jersey).

Representative anionic fluorine-free surfactants include alkyl sulfates, for example, sodium n-octyl sulfate (e. g., Sipex OLS, commercially available from Rhone-Poulenc Corp., Cranbury, New Jersey) and sodium decyl sulfate (e. g., Polystep B-25, commercially available from Stepan Co. of Northfield, 111.); alkyl ether sulfates of the general formula CjH2j+l (OC2H4) gOS03Na; alkyl aryl sulfonates of the general formula CjH2j+,- C6H4SO3Na; alkyl sulfonates of the formula CjH2j+l S03Na, wherein j is between 6 and 10 inclusive and g is between 1 and about 10 inclusive (e. g., WitcolateTM 7093, an alkyl ether sulfate where j is 6-10 and g averages about 2, commercially available from Witco Corp., Chicago, Illinois); and imidazole-based surfactants such as those described in U. S. Pat. No. 3,957,657 (Chiesa, Jr.), which is incorporated herein by reference.

Useful amphoteric surfactants include those which comprise a hydrocarbon chain with a length in the range from about 8 to 14 carbon atoms.

Examples of such hydrocarbon chains include caprylo (Cg), capro (C, o), lauro (Cl2), or coco (C, z_, 4). Specific such amphoteric surfactants include hydroxysultaines (e. g., cocoamidopropyl hydroxysultaines; alkyl ether hydroxypropylsultaines); dipropionates (e. g., disodium cocoampho dipropionates, disodium capryloampho dipropionates, sodium laurimino dipropionates); diacetates (e. g., disodium

cocoampho diacetates); acetates (e. g., sodium lauroampho acetates, sodium cocoampho acetates); propionates (e. g., sodium cocoampho propionates, sodium capryloampho propionates; capro amphocarboxy propionates, amino propionates); betaines (e. g., lauramidopropyl betaines, cocamidopropyl betaines); amidopropylsultaines (e. g., cocoamidopropyl sultaines); and hydroxy-substituted amphoteric sulfonates (e. g., sodium capryloampho hydroxypropyl sulfonates)..

Preferred commercially available amphoteric surfactants include the following: Mirataine H2C-HA (sodium laurimino dipropionate, C12H25N+(H)(CH2CH2COO-)(CH2CH2COO-Na+)); MiranolTM C2M-SF Conc. (sodium cocoampho propionate, C11-13H23-27CONHCH2CH2N+(CH2CH2COO-)(CH2CH2COOH)(CH2CH2OH)); MirataineTM CB (cocamidopropyl betaine, C11-13H23-27CONHCH2CH2CH2N+(CH3)2CH2COO-)); Mirataine TM CBS (cocoamidopropyl hydroxysultaine, C11-13H23-27CONHCH2CH2CH2N+(CH3)2(CH2CH (OH) CH, S03-)); MiranolTM JS Conc. (sodium caprylampho hydroxypropyl sulfonate, C7Hl5CONHCH2CH2N (CH2CH2OH) (CH2CH (OH) CH2SO3-)Na+) ; MiranolTM JAS-50% (sodium capryloampho propionate, <BR> <BR> C7HI5CONHCH2CH2N+ (CH2CH2COO-) (CH2CH2COOH) (CH2CH20H));<BR> <BR> MiranolTM J2M-SF Conc. (disodium capryloampho dipropionate,<BR> <BR> C7H, 5CONHCH2CH,, N- (CH2CH2COO-) (CH2CH, COO- Na-) (CHCH20H)) ; Mirataine BB (lauramidopropyl betaine, C11H23N(CH3)2CH2COO-; and Rewoteric AM CAS-15 (cocoamidopropyl sultaine, C11-13H23-27CONHCH2CH2CH2N+(CH3)2(CH)2nCOO-).

MirataineTM, MiranolTM, and Mirapon hydrocarbon surfactants are all commercially available from Rhone-Poulenc Corp., Cranberry, New Jersey; Rewotericz hydrocarbon surfactants are commercially available from Witco Corp., Greenwich, Connecticut. The above mentioned preferred amphoteric surfactants are especially effective in combination with the fluorinated amine oxide surfactants of this invention to formulate superior AFFF agents. Not only is the

foamability of the agents greatly improved, but the surface tensions of the premixes made from the concentrate compositions are very low, for example below about 17 dynes/cm, and the interfacial tension at about 2.0 to 3.5 dynes/cm is optimum for film formation. This allows the fire-fighting compositions to form thick and stable non-emulsified aqueous films which spread well over the fuel or other liquid, leading to exceptional fire-fighting performance.

In general, the fluorine-free surfactant can preferably be present in the fire-fighting concentrate composition of the invention in an amount from about 1 to 30 wt-%, based on the total weight of the concentrate.

Additional non-surfactant components may optionally be added to the fire-fighting compositions of the present invention. Solvents may be present to facilitate solubilization of the fluorinated amine oxide surfactant and/or the fluorine-free surfactant in water. Suitable solvents include, ethylene glycol, glycerol, diethylene glycol monobutyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol monomethyl ether, and hexylene glycol. These solvents may also act as foam stabilizers and freeze-protection agents. The amount of solvent used is typically between about 5 wt-% to 50 wt-% of the concentrate composition.

Stabilizers and thickeners may also be added to the fire-fighting concentration to further enhance foam stability after aeration of the premix.

Examples of useful stabilizers and thickeners include partially hydrolyzed proteins, starches, polyvinyl resins (e. g., polyvinyl alcohols, polyvinylpyrrolidone, polyacrylamides and carboxyvinyl resins), alkanolamide surfactants, long chain alcohols, polyethylene glycol, guar gum, and locust bean gum. In particular, polysaccharide resins and biogums such as xanthan gum can be incorporated as foam stabilizers in fire-fighting compositions intended to be used on polar solvent fires such as alcohols, ketones, esters and ethers. Additionally, other additives may be useful to improve polar solvent resistance, including fluorochemically modified oligomeric acrylates or polymers.

Corrosion inhibitors, buffers, antimicrobial or other preservative agents, and divalent ion salts may also be employed. Additional components that

may be added to the fire-fighting compositions of this invention are detailed in U. S. Pat. Nos. 5,085,786 (Alm et al.) and 3,772,195 (Francen), both of which are incorporated herein by reference.

The total amount of solids attributable to non-surfactant components, if such components are present, should be such that the concentrate composition maintains its foamability, and that the density of the foam prepared is less than 0.5glCc, preferably less than 0.2glcc. Generally the amount of solids attributable to non-surfactant components such as stabilizers, thickeners, corrosion inhibitors, buffers, antimicrobial agents, and divalent ion salts will be less than about 20% by weight, preferably less than about 10% by weight, of the concentrate.

The concentrate compositions of the invention are highly storage stable. They pass U. S. Government specification MIL-F-24385C, which requires that foaming and film-forming properties of concentrates not be adversely affected if the concentrate and its fresh and sea water premixes are stored at 65°C for 10 days. These conditions are designed to simulate a room temperature storage period of approximately 10 years.

The fire-fighting compositions of the invention are generally provided as 1 %, 3% or 6% concentrates, which, as described above means they can be diluted with 99%, 97%, or 94% by volume water respectively, to form a fire- fighting premix composition. Although the concentrates are conventional within the industry, fire-fighting compositions of any useful concentration may be prepared.

The fire-fighting concentrates of the invention are used by diluting an appropriate amount of the concentrate with water, forming a foam, and applying the foam to a burning liquid. In practice, sea water or fresh water is typically delivered through a fire hole under pressure, to induct or inject from about 1 % to 6% by volume of the fire-fighting concentrate into the hose by venturi effect to form a premix. This premix is aerated by use of an air aspirating nozzle located at the outlet of the hose, forming foam. The foam is applied to a body of burning fuel

or another flammable liquid and spreads quickly to blanket the surface for rapid extinguishment of the fire.

As the foam on the surface of the flammable liquid drains, an aqueous film is formed which will tend to reform if disturbed or broken. This aqueous film prevents reignition of the fire by sealing in flammable vapors, and sealing out air.

Fire-fighting compositions that contain the fluorinated amine oxide surfactants of the invention strongly adsorb to substrates comprising sludge, various types of soils, sand, clay and other substrates. For example, if a fire- fighting composition of the present invention is contacted with such a substrate, the aqueous solution that drains from the substrate can have a very low concentration of fluorinated amine oxide surfactant, for example from about 0 to 50 ppm (parts per million). The balance of the fluorinated amine oxide surfactant has adsorbed onto the substrate, and can be recovered, for example, by removing that portion of the substrate that has adsorbed surfactant, drying the substrate, and extracting the fluorinated amine oxide surfactant with organic solvents. The fluorinated amine oxide surfactants can then be isolated and recovered. This feature, which allows the surfactant to be removed from the ground and prevents the surfactant from reaching groundwater, minimizes the potential effects that these compounds, if not collected, would have on the environment.

The invention is further described by the following examples, which are understood to be illustrative only and do not limit the claimed invention.

Test Methods The following test methods and procedures were used to evaluate the performance of the fluorinated amine oxide surfactants and AFFF agents made therefrom: Foam Expansion and Drain Time: Foam expansion, defined as the volume of foam produced divided by the volume of liquid used to produce the foam, is determined as described in U. S. Government Military Specification MIL- F-24385, Revision F. In this test, a standard National Foam System 2 gal/min (7.6

L/min) nozzle is used to generate foam from a 3% premix (i. e., 3 parts of concentrate mixed with 97 parts of water) contained in a 2 gal (7.6 L) stainless steel pressurized tank. The foam is deflected off a 45° backstop into a 1-L tared graduated cylinder, and the weight of the cylinder plus foam is recorded in grams.

The foam expansion is calculated by dividing the actual volume (mL) (i. e., not the nominal 1-L volume) of the graduate by the weight (g) of the foam.

The 25% drain time for the foam, also described in U. S. Government Military Specification MIL-F-24385, is defined as the amount of time after foam collection for 25% of the weight (i. e., volume) of foam to drain to the bottom of the graduate (read as milliliters in the graduated cylinder, assuming a specific gravity of 1.0).

Film-Forming and Sealing: The Film-Forming and Sealing Test determines whether an AFFF premix is capable of forming a stable film on n- heptane. In this test, an inverted No. 8 flathead screw is placed in the center of a 10 cm diameter glass petri dish containing 40 mL of n-heptane (>99% purity, surface tension = 20.4 dynes/cm). An aqueous film is generated on the n-heptane surface by gently applying dropwise 0.75 mL of test premix solution from a 1 mL disposable syringe to the tip of the inverted screw over an approximately 30 to 60 second time period. Two minutes after applying the first drop of premix solution, a small flame is moved approximately 0.5 inch (1.3 cm) over the n-heptane surface for about 10 seconds. For a good vapor seal, no sustained ignition shall result, though a small intermittent flash is permitted.

Surface Tension (ST): Surface tensions of aqueous surfactant solutions and 3% AFFF premixes were measured in units of dynes/cm using a K-12 Processor Tensiometer and 665 DosimatTM measuring method with Software K 122, available from Kruss GmbH, Hamburg Germany. The surface tension should be as low as possible for the premix to have its maximum film-forming effectiveness.

Interfacial Tension (IT): Interfacial tensions (in dynes/cm) of the interface formed between 3% premixes and n-heptane (>99% purity, surface tension = 20.4 dynes/cm) were measured using a K-12 Processor Tensiometer.

The interfacial tension should be as high as possible to produce thick, stable films and to avoid emulsification of the fuel, yet should be sufficiently low to allow for a positive spreading coefficient.

Spreading Coefficient (SC): The Spreading Coefficient (in dynes/cm), is calculated from the surface and interfacial tension values measured with the premixes as follows: SC = ST (fuel)- [ST (premix) + IT (premix/fuel)] A positive Spreading Coefficient is a minimum requirement for the premix to form a vapor sealing aqueous film on the surface of the fuel.

Critical Micelle Concentration (CMC): The critical micelle concentration is defined as the concentration at which further surface tension is no longer lowered with increasing levels of surfactant. To determine CMC, surface tension is measured as a function of surfactant concentration using a K-12 Processor Tensiometer in conjunction with a 665 Dosimat automatic surfactant injection device (also commercially available from Kriss GmbH). Surface tension is then plotted vs. log concentration and the data points are connected. The resulting curve has a nearly horizontal flat portion at concentrations above the CMC and has a negative steep slope at concentrations below the CMC. The CMC is calculated as that concentration of the curve where the flat portion and steep slope connect.

Fire Extinguishment and Burnback Test: The fire test procedure used to evaluate AFFF agents in the examples is outlined in the U. S. Department of Defense Military Specification No. MIL-F-24385, Revision F, Section 4.7.13.2.

According to this procedure, 3.0 gallons of a 3.0% (vol) premix is made by mixing 3 volumes of a 3% concentrate with 97 volumes of synthetic sea water (the sea water being made in accordance with ASTM Du 141). The premix is poured into a tank with attached hose and foam nozzle, and the filled tank is pressurized. Then 15 gallons (57 L) of aviation gasoline is poured onto a water base contained in a 50 ft2 (4.7 m2) circular pit. After the gasoline is ignited and allowed to preburn for 10

seconds, an operator aggressively attacks the fire using foam generated from the premix by passing the premix through a National Foam System air-aspirating nozzle at a flow rate of 2.0 gal/min. The percent extinguishment of the fire is recorded at every 10 second mark until the fire is fully extinguished. Also, the exact extinguishment time is recorded. The efficiency of fire extinguishment is quantified as the"40 second summation,"which is defined as the sum of the percent extinguishment values recorded at the 10,20,30 and 40 second marks.

After extinguishment, the foam is continually applied to the pit until the 90 second mark, at which time the premix solution is exhausted.

Within 60 seconds after extinguishment, a one foot diameter circular pan containing burning gasoline is placed at the center of the circular pit. The time for 25% (12.5 ft2, or 1.16 m2) of the foam-covered area to become reinvolved in flames is measured and is recorded as the"25% burnback time." SURFACTANT GLOSSARY Fluorinated Amine Oxide Surfactants F-1 : CgF17SO2NHC3H6N (CH3) 2-->O was prepared using the following procedure.

116.8 g (0.2 mol) of CgF17SO2NHC3H6N (CH3) 2 (made as described in Example 1 of U. S. Pat. No. 2,759,019 except that 3- (N, N- dimethylamino) propylamine was substituted for beta-diethylaminoethylamine) and 100 g of ethanol were added to a 3-necked round-bottom flask equipped with stirrer, thermometer and water condenser. The mixture was stirred, heated to 65- 70°C, and 45.2 g (0.4 mol) of 30% aqueous H202 was added over a one hour period. The resulting solution was heated and stirred at 70°C for a total of 12 hours. 0.4 g of decolorizing/activated charcoal was added, and the mixture was gently refluxed for one hour. The refluxed mixture was filtered through CeliteTM filter agent (commercially available from Aldrich Chemical Co., Milwaukee Wisconsin), and the filtrate was evaporated to dryness to produce a waxy solid. 1H

NMR analysis in D2O/KOD confirmed that conversion to the desired amine oxide was greater than 99%.

F-2 to F-15: The following fluorinated amine oxide surfactants were made using the same general procedure as with F-1: F-2: C10F21SO2NHC3H6N (CH3) 2-->O F-3: C9F19CONHC3H6N (CH3) 2-->O F-4: CnF23CONHC3H6N (CH3) 2-->O F-5: C4F90 [CF (CF3) CF20] 2CF (CF3) CONHC3H6N (CH3) 2-->O F-8 : C6F13S02NHC3H6N (CH3) 2-->O F-9: C6F13C2H4SO2NHC3H6N (CH3) 2-->O F-10: C7F15CONHC3H6N (CH3) 2-->O

F-15: C5F1 loC2F4C (o) N (H) C3H6N (CH3) 2-->o Hydrocarbon Surfactants H-1: Sipex OLS, 33% active solution of sodium n-octyl sulfate, commercially available from Rhone-Poulenc Corp., Cranbury, New Jersey.

H-2: MiranolTM C2M-SF, 39% active solution of disodium cocoampho dipropionate, commercially available from Rhone-Poulenc Corp., Cranbury, New Jersey.

H-3: MiranolTM JS, 49% active solution of sodium caproampho hydroxypropyl sulfonate, commercially available from Rhone-Poulenc Corp., Cranbury, New Jersey.

H-4: MiranolTM S2M-SF, 39% active solution of caproampho carboxypropionate, commercially available from Rhone-Poulenc Corp., Cranbury, New Jersey.

H-5: MirataineTM CBS, 43.5% active solution of cocoamidopropyl hydroxysultaine, commercially available from Rhone-Poulenc Corp., Cranbury, New Jersey.

H-6: MirataineTM CB, 30% active solution of cocoamidopropyl betaine, commercially available from Rhone-Poulenc Corp., Cranbury, New Jersey.

H-7 : MirataineTM COB, 30% active coco/oleamidopropyl betaine, commercially available from Rhone-Poulenc Corp., Cranbury, New Jersey.

H-8 : TritonTM X-305,70% active polyethoxylated (30) octylphenol, commercially available from Union Carbide Corp., Danbury, Connecticut.

H-9 : MiranolTM C2M-Conc. NP, 50% active disodium cocoampho diacetate, commercially available from Rhone-Poulenc Corp.

H-10: Miranol HMA, 38% sodium lauroampho acetate, commercially available from Rhone-Poulenc Corp.

H-11: Rewoteric AM CAS-15,50% cocoamidopropyl sulfobetaine, commercially available from Witco Corp., Greenwich, Connecticut.

H-12: MiranolTM Ultra C-32,39% sodium cocoampho acetate, commercially available from Rhone-Poulenc Corp.

H-13: Rewoteric AM HC, 50% coco sulfobetaine, commercially available from Witco Corp.

H-14: Mirapon Excel 825,30.5% sodium cocoampho acetate, commercially available from Rhone-Poulenc Corp.

H-15: MiranolTM CM-SF Conc., 37% sodium cocoampho propionate, commercially available from Rhone-Poulenc Corp.

H-16: MiranolTM JAS-50,50% sodium capryloampho propionate, commercially available from Rhone-Poulenc Corp.

H-17: MiranolTM J2M-SF Conc., 38.5% disodium capryloampho dipropionate, commercially available from Rhone-Poulenc Corp.

H-18: Mirataine BB, 30% lauramidopropyl betaine, commercially available from Rhone-Poulenc Corp.

H-19: MirataineTM JC-HA, 42% proprietary aminopropionate, commercially available from Rhone-Poulenc Corp.

H-20: Mirataine Tm BET 0-30, 30% oleamidopropyl betaine, commercially available from Rhone-Poulenc Corp.

H-21: MirataineTM ASC, 42.5% alkylether hydroxypropyl sultaine, commercially available from Rhone-Poulenc Corp.

H-22: Mirataine H2C-HA, 30% sodium laurimino dipropionate, commercially available from Rhone-Poulenc Corp.

H-23: MiranolTM J2M Conc., 49% disodium capryloampho diacetate, commercially available from Rhone-Poulenc Corp.

H-24: MiranolTM BM Conc., 38% disodium lauroampho diacetate, commercially available from Rhone-Poulenc Corp.

EXAMPLES Examples 1-7 and Comparative Examples C1-C11 In Examples 1-7 and Comparative Examples C1-C8, fluorinated amine oxide surfactants F-1 through F-15 were dissolved in deionized water at various solids concentrations and the surface tension of each resulting aqueous surfactant solution was measured. Then the critical micelle concentration (CMC) was determined for each surfactant. The CMC for each surfactant and the

corresponding surface tension are presented in Table 1; an asterisk (*) indicates low surfactant water solubility (i. e., a solubility of 500 ppm or less).

Adsorption of each fluorinated amine oxide surfactant to nutrient sludge was measured using the following test procedure, which is a modification of the USEPA Aerobic aquatic biodegradation inoculum medium. A large batch of test nutrient sludge having a suspended solids count in the range of 1700-2100 mg/L was allowed to aerated for one day. The molecular weight for each fluorinated amine oxide was calculated to determine the proper amount of each surfactant (mg) to add to 500 mL of nutrient sludge to give a concentration of approximately 1 millimolar. This calculated amount of surfactant was weighed into a glass vial, and 20-25 mL of water that was purified through a MilIiQTM Ultra Purification System (available from Millipore, of Bedford, MA) was then added. The vial was then capped and was shaken until the surfactant dissolved or overnight (about 16 hours), whichever was sooner. The resulting aqueous surfactant solution was then quantitatively transferred to a NalgeneTM 1-L Erlenmeyer flask along with 500 mL of the aerated nutrient sludge. The flask with its contents was placed for 2 minutes on an orbital shaker set at 100-130 rpm. After shaking, the suspended solids were allowed to settle for about 2 minutes. The liquid was then separated from the solids using one of two equivalent techniques: (1) After shaking, the suspended solids were allowed to settle for about 2 minutes, and a 5-1 OmL aliquot of the supernatant liquid was filtered using a plastic syringe equipped with a 45 micron filter; (2) Immediately after shaking, a 5-10 mL aliquot of the test solution was transferred to a 15 mL centrifuge tube, the contents in the tube was centrifuged to separate the solids from the liquid portion, and the liquid was then decanted off.

The surface tension of the filtrate or decantate was measured using a K-12 Process Tensiometer, and the value was recorded as the surface tension after day 0 (actually, after 2 minutes) in Table 1. After each surface tension measurement had been completed, each of the sludge/surfactant-containing flasks was placed back on the shaker. After 1,7,14 and 28 day intervals, the filtering and surface tension measuring processes were repeated for the contents of each flask. The surface tension values measured after days 14 and 28 are presented in Table 1. An entry of"N/R"indicates that the surface tension measurement was not taken on that particular day.

Table 1

ST, FC dynes/CMC, ST after day: Ex. Surf. cm ppm 0 1 7 14 28 1 F-1 15. 5 22 15. 6 51. 5 N/R N/R 56.1 2 F-2 16. 5 500* 16. 2 71. 6 71. 2 71.5 71.6 3 F-3 16. 5 50 16. 5 70.3 71.3 4 F-4 17. 7 20* 18. 7 71.7 71.7 5 F-5 16. 5 22 16. 0 71.3 N/R N/R 71.5 6 F-6 19. 3 1000 19. 8 40. 6 N/R N/R 35. 7 7 F-7 15. 5 22 15. 5 17.8 N/R N/R 50.7 C1 F-8 15. 8 100 15. 8 29. 8 N/R N/R 30. 0 C2 F-9 20. 0 600 15. 2 32.0 N/R N/R 28.5 C3 F-10 15. 0 100 15. 6 23. 8 19. 4 19. 6 21. 8 C4 F-ll 20. 0 600 20. 0 34.7 32.6 C5 F-12 18. 1 800 19. 5 23.7 24.1 C6 F-13 16. 3 500 16. 3 24. 8 24. 7 22. 3 21. 8 C7 F-14 16. 7 100 16. 8 28.9 N/R N/R 29.0 C8 F-15 15.6 140 15.8 26. 0 N/R 28.2 26.5 The data in Table 1 show that nearly all of the fluorinated amine oxide surfactants, both inside (F-1 to F-7) and outside (F-8 to F-15) of this invention, provide good surface tension reduction in water, some at very low critical micelle concentrations. However, only fluorinated amine oxide surfactants of this invention (F-1 to F-7) also strongly adsorbed to the sludge (Examples 1-7). The increased surface tension measurements of these solutions by day 28 indicate that the fluorinated amine oxide surfactant had adsorbed onto the substrate, and were no longer in solution. For instance, the concentration of fluorinated amine oxide surfactant F-1 in aqueous solution with the sludge was reduced from the initial concentration of about 600 ppm, to a measured concentration of less than 5 ppm, thus effectively removing the fluorinated compound from the aqueous solution and minimizing its potential effect on the environment.

In a second experiment using surfactant F-1 of Example 1, the nutrient sludge-fluorochemical complex was found to be quite stable, even after autoclaving. The measured surface tension of solution from a one-day complex sample, before autoclaving was 66 dynes/cm, indicating an aqueous surfactant concentration of under 1 ppm. The samples were autoclaved at 121 °C and 15 psi (776 Torr), for 15 minutes (total of one hour cycle time which includes warmup, autoclaving, and cool down), was 50 dynes/cm, indicating an aqueous surfactant concentration of approximately 1 ppm. This is in contrast to the surfactant concentration before contacting with the nutrient sludge, where the measured surface tension was 15.6 dynes/cm, at an aqueous surfactant concentration of approximately 600 ppm.

Examples 8-15 Examples 8-15, formulated to be 3% fire-fighting concentrate compositions contained the following ingredients, including 1 wt-% of hydrocarbon surfactants H-1 (short chain ionic surfactant), H-2 through H-7 (amphoteric surfactants) or H-8 (nonionic surfactant): 3% AFFF Concentrate (% solids by weight) : 1.5%-fluorinated amine oxide surfactant F-1, CgF 17S02NHC3H6N (CH3) 2-->O 4.0%-hydrocarbon surfactant H-1, sodium n-octyl sulfate 1.0%-hydrocarbon surfactant (varied from H-1 to H-8) 25.0%-dipropylene glycol n-propyl ether remainder-deionized water and surfactant co-solvents (to add up to 100%) (pH of each concentrate was adjusted in a range of 8.3 using glacial acetic acid) Three parts by volume of the resulting concentrates were diluted with 97 parts by volume of synthetic sea water (ASTM D1141-52) to form sea water premixes which were evaluated for AFFF performance using the following

laboratory tests: Foam Expansion and Drain Time, Film-Formation and Sealability, Surface Tension and Interfacial Tension. The AFFF concentrate formulations and test results from the 3% sea water premixes are presented in Table 2.

Table 2 Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. 8 9 10 11 12 13 14 15 Hydrocarbon H-1 H-2 H-3 H-4 H-5 H-6 H-7 H-8 Surfact.: Lab Performance Test: Foam 8.0 8.5 7.6 8.6 8.5 8.9 8.5 7. 6 Expansion 25% Drain 252 276 252 258 275 264 260 260 Time (seconds) Film-Forming Fail Pass Fail Pass Pass Pass Pass Pass &Sealing Surf. Tens. 16.3 16.2 16.2 16.4 16.4 16.8 16.5 16.4 (dynes/cm) Int. Tens. 2.6 2.0 3.1 (dynes/cm) The data in Table 2 show that useful AFFF concentrates can be made by incorporating fluorinated amine oxide surfactant F-1 with a variety of hydrocarbon surfactants. The combination of F-1 with hydrocarbon surfactant H-1 (sodium n- octyl sulfate, a short chain anionic surfactant having a carbon chain length of 8) and amphoteric hydrocarbon surfactants H-2, H-4, H-5 or H-6 (MiranolTM C2M- SF, MiranolTM S2M-SF, MirataineTM CBS, or MirataineTM CB) gave especially good foam properties and thick, stable, vapor-suppressing aqueous films; all desirable fire-fighting qualities.

Example 16 In Example 16, a 3% AFFF concentrate containing fluorinated amine oxide surfactant F-l, short chain ionic hydrocarbon surfactant H-1, and anionic hydrocarbon surfactant H-2 was formulated as follows (% solids by weight): 3% AFFF Concentrate 1.5%-fluorinated amine oxide surfactant F-1 2.0%-hydrocarbon surfactant H-1 3.0%-hydrocarbon surfactant H-2 25.0%-dipropylene glycol n-propyl ether remainder-water pH adjusted to 8.3 with 25% aqueous sodium hydroxide.

3% fresh water premixes and 3% sea water premixes were prepared, and the resulting premixes were evaluated in the laboratory for Foam Expansion and 25% Drain Time, Film-Formation and Sealability, Surface Tension and Interfacial Tension. The Fire Extinguishment and Burnback Test was also run with each premix.

Results from lab evaluations and fire tests are given in Table 3, along with the minimum requirement for passing each test according to MIL-F-24385F Military Specification.

Table 3 3% Fresh 3% Sea Spec. Lab Performance Test : Foam Expansion (ratio) 9.0 8.4 5.0 25% Drain Time (seconds) 246 275 2150 Film-forming & Sealing Pass Pass Pass Surface Tension (dynes/cm) 16.2 16.6 17.0 Interfacial Tension (dynes/cm) 3.8 3.7 < 5.0 Fire Extinguishment & Burnback Test: 40 Second Summation (%) 330 320 Extinguishment Time (sec) 40 41 50 25% Burnback Time (sec) 390 389 2 360

The data in Table 3 show that the fire-fighting premixes passed the military specification fire test, even though the concentrate contained only 1.5% (wt) solids of fluorinated amine oxide surfactant F-1, and the resulting premixes contained only 0.045 wt-% solids of fluorinated amine oxide surfactant F-1. This is in contrast to the AFFF formulation given in British Patent Specification 1 302 612 at page 8 which contained 0.12% (wt) solids of C7F 15cONH (cH2) 3N (CH3) 2-->O (fluorochemical amine oxide surfactant F-10) in the premix. It is also in contrast with the AFFF formulation given in U. S. Pat. No. 3,772,195 (Francen) at col. 15, lines 34-67, which contained 0.24% (wt) solids of C6F13SO2NHC3H6N(CH3)2-- >O (fluorochemical amine oxide surfactant F-8) in the premix.

Examples 17 and Comparative Examples C 12-C 13 In Examples 17 and Comparative Examples C 12-C 13, fire tests were run to compare the fire-fighting performance of 3% sea water premixes made from AFFF concentrates containing fluorinated amine oxides both inside and outside of this invention. Concentrates also contained hydrocarbon surfactants H-1 and H-2.

In Example 17, the concentrate contained fluorinated amine oxide F-1, CgFl7S02NHC3H6N (CH3) 2-->O, which is within this invention.

In Comparative Example C12, the concentrate contained fluorinated amine oxide F-8, C6F13SO2NHC3H6N(CH3)2-->O, which is outside of this invention.

In Comparative Example C 13, the concentrate contained fluorinated amine oxide F-10, C7Fl5CONHC3H6N (CH3) 2-->O, which is also outside of this invention.

In each case, the pH of the concentrate was adjusted to a pH of approximately 8, using acetic acid or sodium hydroxide as appropriate.

Formulations and fire test performance values for Example 17 and Comparative Examples C 12 and C 13 are presented in Table 4.

Table 4 Percent by Weight in : Component in Concentrate: Ex. 17 C. Ex. C12 C. Ex. C13 Fluorinated Amine Oxide F-1 1. 50------ Fluorinated Amine Oxide F-8---2. 00--- Fluorinated Amine Oxide F-10------1.50 Hydrocarbon Surfactant H-1 2.00 2.00 2.00 Hydrocarbon Surfactant H-2 3.00 3.00 3.00 Diethylene Glycol Monobutyl Ether 20.00 20.00 20.00 Deionized Water, Surfactant Solvents 73.50 73.00 73.50 Fire Extinguishment & Burnback Test: (3% sea water premixes) 40 Second Summation (%) 329 < 160 250 Extinguishment Time (sec) 32 > 90 89 25% Burnback Time (sec) 440 not run 130 The data in Table 4 show that the fire-fighting premix containing fluorinated amine oxide surfactant F-1 (Example 17) was clearly superior to the premix containing either fluorinated amine oxide surfactant F-8 (Comparative Example C12) or fluorinated amine oxide surfactant F-10 (Comparative Example C13) at controlling, extinguishing and securing the fire.

Examples 18-35 The same lab formulation procedure and evaluation tests were repeated as presented earlier in Examples 8-15 and Table 2, except this time a different series of hydrocarbon amphoteric surfactants (H-9 to H-24, repeating H-1 as a control) was evaluated. In other words, the same 3% AFFF concentrate was employed, and again each hydrocarbon amphoteric surfactant was incorporated into the test concentrate at 1 % solids by weight. The same lab evaluation tests were run except the Film-Forming and Sealing Test was not performed. Results, presented in Table 5, also include a listing of the amphoteric hydrocarbon surfactant group.

Table 5

HC Amphoteric Foam 25% D. T. Surf. Tens. Int. Tens. Ex. Surf. Group Exp. (sec) (dynes/cm) (dynes/cm) 18 H-9 diacetate 8. 5 252 16. 6 1.6 19 8.524317.21.1acetate 20 8.825316.52.9amidopropyl- sultaine 21 H-12 acetate 8. 8 257 16. 8 1.6 23 H-14 acetate 8. 7 244 16. 7 1.6 24 H-15 propionate 9. 1 270 16. 7 13 25 H-16 propionate 7. 6 244 16. 4 3.6 26 H-17 dipropionate 7. 2 251 16. 0 3.6 27 H-18 betaine 9. 3 260 16. 6 2. 3 28 H-19 propionate 6. 6 256 16. 5 4.2 29 H-20 betaine 7. 7 242 16. 2 1.9 30 H-21 hydroxy-5. 8 243 16. 0 2. 8 sultaine 31 H-22 propionate 8. 8 235 173 2. 5 32 H-23 diacetate 7. 6 250 16. 0 3.9 33 H-24 diacetate 8. 5 256 18. 0 1.2 34 H-13 unsubstituted 8. 7 253 17. 3 I. 5 sultaine 35 H-l (anionic HC) 7. 2 239 16. 5 4.5 The data in Table 5 show that the amphoteric hydrocarbon surfactants of this invention imparted generally good performance to the 3% AFFF concentrate.

In Example 34, Hydrocarbon H-13, an unsubstituted sultaine outside of this invention, performed relatively poorly, giving a surface tension greater than 17 dynes/cm and an interfacial tension of less than 2 dynes/cm. In Example 35, where no amphoteric hydrocarbon surfactant was used, poorer foam properties and too high an interfacial tension resulted.