IL32098A - Fire-fighting foam - Google Patents

Description

MD.21019/2102.θ/21386/23 5θ/211ι-51 This invention relates to novel compositions for making aqueous foams suitable for applying to burning materials, especially to burning liquids for example hydrocarbon fuels, in order to extinguish flames and prevent reignition* It is known to use aqueous foams in fire-fighting, either alone or together with finely-divided dry fire-extinguishing chemicals, for example sodium and potassium bicarbonates. The latter extinguish lames when dispersed into the combustion zone but reignition is always possible as long as an exposed surface of fuel remains. To prevent this it is useful to smother the surface with a foam, which if it is continuous and stable under the local prevailing conditions can much reduce the chance of reignition occurring,, Among known foams for this purpose are those based on ~ materials derived from proteins and often described as protein foams. They are not ineffective and are relatively cheap, but require to be spread in thick, heavy layers that are easily ruptured. Since protein foams do not flow readily they have no self-healing properties hence rupture of the foam layer exposes fresh areas of fuel liable to reignite. Protein foams are often rendered unstable and made to collapse by some of the finely-divided chemical powders used to extinguish the flames, particularly when these chemicals have been treated with certain free-flowing or anti-caking agents for example silicones.

Also known for fire-fighting are foams based on surface-active agents containing perfluoroalkyl groups in the molecule. Such foams are stable in the presence of silicone-coated powdered materials, for example sodium and potassium bicarbonates, they spread readily and quickly re-form after rupture.

We have now discovered that certain fluorine-containing surface-active agents derived from tetrafluoroethylene oligomers can in aqueous solutions be readily foamed to give foams having good stability, good compatibility with fineOy-divided fire-extinguishing chemicals such as sodium bicarbonate, high resistance to attack by flame or by burning fuels, and good flow properties over the surface of hydrocarbon fuels.

Vie have also found that some surface-active agents derived from branched tetrafluoroethylene oligomers and containing branched perfluoro groups are particularly effective when incorporated in foams derived from ether foam-producing materials.

The oams are thereby rendered more mobile giving them greater sealing and re-sealing properties and making them able to 3pread more quickly over a surface, whilst preserving or even increasing their thermal stability and increasing their resistance to burning when in contact with hydrocarbon fuels and fires involving water-miscible solvents such as alcohols. The foams are also rendered more stable to contact with dry chemical powder extinguishers, A further advantage of the addition of the surface active agents derived from oligomers is that they impart to foams increased tolerance to fuels especially to petrol.

Thus according to the present invention there X3 provided a method of producing a fire-extinguisliing foam which comprises foaming an aqueous composition comprising a surface-active agent derived from a branched oligomer of tetrafluoroethylene (G^^)n wherein n is an integer equal at least to 1+, There is further provided a composition comprising at least one surface-active agent derived from a branched oligomer of tetrafluoroethylene wherein n is an integer equal at least to . and at least one further agent, not derived from a branched oligomer of tetrafluoroethylene, for producing a fire-fighting foam, As a further aspect of the invention there is provided a method of fighting a fire which comprises applying to the fire a foam produced from an aqueous composition comprising a surface-active agent derived from a branched oligomer of tetrafluoroethylene (Gg?^)a wherein n is an integer equal at least to · The branched oligomers of tetrafluoroethylene may be produced for example by the process described in B,P. 1,082,127· A variety of different structures may be produced but in general terms all the oligomers are highly-branched perfluoroolefins.

For example, the fluorocarbon group in from which the pentamer oxybenzene surface-active agents are derived, appears to have the following structure °2F5 °F3 CP, - 0 - c » c - \ C2P5 CP3 Similarly, the fluorocarbon group in CgF-^O.CgH.., is derived from tetramer having the following structure CF,CF„ - G - C - CP-CP, 3 2 j 2 .5 CP^ In the case of hexamer derivatives, the structures are based on a number of mixed isomers of hexamer. Evidence or the structure of two of the isomers for hexamer is consistent with the following structures CJ?, CP CP, ll / CP, - C - C - 3 / CPgCP, CP, °2P5 The surface-active agents of this invention are derived from the tetrafluoroethylene oligomers by a variety of chemical reactions, all designed to attach suitable hydrophilic groups to the carbon skeleton of the oligomer. In certain reactions, for example those described in U.K. Specification Nos. 1,130,822 and l,¾.8,if86, nueleophiles containing reactive hydrogen atoms or other reactive atoms abstract fluorine from the oligomer molecule and make a covalent link between the oligomer and the nucleophile.

Patent Specification Nos. 1,155, 607 In other copending U.lv. k^ d hhkl 14 ' Mi and , 176, 492 bfcf-> /$~f reactions are described wherein the oligomer structure is modified; the nucleophilic attack removes some carbon and fluorine atoms and the resulting oligomer residue, besides being smaller, is observed to contain one or more hydrogen atoms attached to the remaining carbon atoms.

The surface-active agents of this invention are among those described in the above applications or are related to or derived from the products described therein and may contain anionic, cationic, amphoteric or neutral hydrophilic groups, For example the surface active agent which can be described as tetraf luoroethylene pentameroxybenzene sodium sulphonate, can be made by a reaction betv/een pentamer (C F^)-. and N OO^H^SO^Na, to give the product and sodium fluoride ; it can also be made by reacting pentamer and phenol in the presence cf a base to give sulphonating the latter with oleum to give C-, ~F, Λ00>Η, S0,H and then neutralising this with sodium alkali. 19 o h- j Both tetramer and hexamer can react with phenol to give respectively sulphonic acids and their sodium salts can be made in a similar manner.

The corresponding potassium and lithium, ammonium or tetraalkyl ammonium salts can be made by the same or a similar route. The acids or the corresponding acid chlorides may be reacted with suitable diamines e.g. aliphatic diamines containing 1-6 carbon atoms, to form an amide link at one end of the diamine, the free amine being subsequently quaternised to form a cationic centre.

For example compounds having the formula A ∞ay ¾e made from oligomer oxybenzene sulphonic acid chlorides and aliphatic amines. In such compounds n may be 2+., 5 or 6 m may be from 1 to 6, preferably 3 X, Y and Z may be the same or different and represent alkyl groups, preferably methyl or ethyl groups and A is any anion preferably an anion derived from a quatemisation reaction.

The quatemisation reaction may be conducted with an alkyl halide preferably an alkyl bromide or iodide or an alkyl sulphate preferably dimethyl sulphate. Anions may be exchanged subsequently if desired, and therefore the surface-active agents used may contain any anion which allows adequate solubility in water.

Examples of surface active compoundsfor use as foaming agents which may be made from the appropriate oligomer/cxybenzene sulphonic acids or acid chlorides are G8F15OC6¾.S°3 N^ derived from the tetramer CgE'^ C10i'l9OC6H-|.S03 M¾+ derived rom ^ pentamer C10?2o G10F10C6H S02,H^CH2^3 N+ ^CH ^3 I_ derived ^0111 the pentamer 1QF2Q The reaction of oligomers with the methyl esters of sodium p-hydroxy benzoic rfefohbi-6 acid and the hydrolysis of the product to give oligomer oxybenzoic acid is also described in U.K. Patent No. 1,130,822, From such oxybenzoic acid derivatives of tetramer, pentamer or hexamer, a range of surface-active agents may be made, for example salts having the formula a is 5 or 6, M may be an alkali metal, preferably sodium, potassium or lithium, the ammonium group, tetraalkyl ammonium, preferably tetramethyl or tetraethyl ammonium, or any other basic group capable of forming salts with benzoic acids for example an aliphatic amino group or a pyridinium group.

•Other surface-active agents may be prepared from the oligomer oxybenzoic acids by reaction of the carboxylic acid (or optionally the acid chloride) with molecules having an I\T-H group, preferably a primary or secondary amino grou » Thus oligomer oxybenzamide derivatives may be made and if the molecules so added contain hydrophilic groups, for example carboxylic acid or salts thereof, in addition to the N-H group surfece-Eictive compounds are made -without further reaction. For example compounds may be made from amino acids having the formula in which L is an alkyl group and M may be a hydrogen atom, an alkali metal atom an ammonium group or tetraalkyl ammonium group.

Alternatively hydrophilic groups may be attached by subsequent reactions, for example by quatemisation of the free amino group when an aliphatic diamine is used, to make compounds of general formula C2nF^-:|OC6H^COM-l(CH2)mN+(XYS) A"* in which m may be a small integer preferably from 1 to 6, X, Y and Z which may be the same or different are alkyl groups preferably methyl or ethyl and A may be any anion obtained from the quatemisation reaction as hereinbefore specified.

The free amino group of a diamine may be converted to an ampholytic group by reaction with a beta-lactone preferably beta-propiolactone whereby compounds of formula C2Fn-lOC6¾.COml(CH2^Μ^ΟΚ,,ΟΟθ" or C2n^10C6H^S02N?l(GH2)mN+( )CH2CH2C00" may be made, wherein n and m are as hereinbefore specified and XY may be alkyl groups preferably methyl or ethyle The oxybenzene derivative may be itself a basic group for example the group -OCgH^CHgNXY ton which X, Y may be hydrogen or alkyl) and it may be attached to the oligomer residue by similar reactions to those described hereinbefore, Hydrophilic groups may be attached at the basic end by quaternisation of the -ΜΧΓ group or by reaction with a lactone to form compounds of formula σ2 Ρ2+-η-1∞6\αΗ2Ν+^ΧΥ^σΗ2σΗ2σ0°" wherein n, X, Y, Z and A are as hereinbefore specified. Examples of compounds which are used as surface-active agents produced from the tetrafluoroethylene pentamer by the reactionsdescribed are C10F190C6H^C0ie(CH2)5 N+(CH3)3 i" C10P19OC6¾.C!ON ^3 )CH2C00" K+ Analogous compounds may in all cases be formed from the tetraraer or the hexamer of tetrafluoroethylene if desired.

In U.K. Patent No. 1,148,-4.86 there are described reactions betvreen tetrafluoroethylene oligomers and amines which eliminate H to form compounds of formula Y be the same or different and are hydrogen, alkyl or aryl groups, Once a basic derivative of the oligomer ha3 been formed surface-active compounds may be made by similar reactions to those hereinbefore described for the oligomer phenol derivatives which terminated in a basic nitrogen-containing group.

Compounds of general formula made in which R is a hydrophilic group made from a diamine as described above or from a glycol by an analogous reaction.

The diamine may be for example an aliphatic diamine which may be converted to hydrophilic groups of formula ~m(CH2)mN+(XYZ) A" or -Ml(CH25mN+( Y)CH2CR"2C0O~ in which m is from 1 to 6, XYZ may be the same or different and may be chosen from hydrogen or alkyl, preferably methyl or ethyl groups, A is an anion obtained from the quaternisation reaction preferably bromide or iodide.

If a glycol is attached to the oligomer the hydrophilic nature of the group R may be obtained for example by condensation of ethylene glycol or polyethylene glycol. Thereby surface-active agents from the tetramer, pentamer, and hexamer having trie formula C2nF- n-l0^C¾C¾^^z~^ mB^' be Taa^3 vhere z *ηβ eg ee of polymerisation of the ethylene glycol prei'erably an integer from 1 to 20 and T is a terminal group preferably methyl or h droxyl.

The reactions between pentamer and alkali metal sulphites or Pat. Specification No 1 155, 607 bisulphites described in may be employed to produce surface-active derivatives of tetrafluoroethylene pentamer having the general formula CgHP^. SO^R.

The group R may be hydrogen, a metal for exarnple an alkali metal, or a nitrogen containing ion for e arnple ammonium or tetraalkyl ammonium. The structure of the fluorocarbon chain appears to be of the form (C^^^ ^3) C,CK 81 c(cpj) wherei one unsaturated carbon atom carries a hydrogen atom rather than a fluorine atom or a fluorinated alkyl radical.

Examples of surface-active agents 'which may be used to produce foams are C^SO" Na+ C9^16S03 K+ ο9¾3ο |Ν+(σ2Η5) ] The sulphonic acid may be used as an intermediate to prepare other surface-active compounds by methods similar to those described for oxybenzene sulphonic acid. For example aulphonamide derivatives may be prepared having the formula preferably example by quaternisation of a nitrogen atom, neutralisation vrit alkali of a carboxylic or sulphonic acid or by polymerisation of ethylene glycol.

Examples of compounds which may be prepared include the compounds C9HFl6S02KH(CH2)3N+(CH3)3I A reaction of pentamer with alkalis described in U.K.

Pat. Spec. No.1, 176 492 4 1/ φφΙίφ. ffyc/J pfflj tul may be used to produce surface-active agents having the fomula - Q, wherein Q is a hydro philic group. In these compounds the structure of the CgF^ group is believed to be \ cp5 - c - The surface-active agent may be, for example, a carboxylic acid (when Q is a hydroxyl group), a salt of carboxylic acid (for example a sodium or potassium salt, an ammonium salt or a quaternary ammonium salt), an amide (when Q is an amino group) or an N-substituted amide. Alternatively, Q may be an es erifying group containing a hydrophilic unit for example a £>olyoxymethylene chain, a polyoxyethylene chain or an alkyl group containing a cationic or anionic centre.

V Examples of oompoun&s derived from which may he used to produce foams include C6F13CH2COO"Na+ or Cg ^CI^COCfK+ C6P13CH2-C0O-(CHgCJHgO)gOHgCI^OGHj OgF^OHgCOMH(CH2)^(CH^)gCHgCHgCOO- and compounds having formula Cg?13CH2COm(CH2)t +(XYZ) A" where m is an integer from 1 to 6 preferably equal to 3 XYZ are alkyl groups which may be the same or different and are preferably methyl or ethyl A** is an anion derived from a quaternisation reaction and compounds having the formula C6P-3CH2COOCH2CH2N+(C2n5)2L~ which may be obtained by the quaternisation of in which L is an allcyl group preferably methyl or ethyl and A is a group capable of becoming an anion preferably bromide, iodide or allcyl sulphate.

In preparing the aqueous foams from any of the foregoing oligomer derivatives surface-active agents can be used individually or as mixtures. Mixtures are often useful for achieving maximum desired foam properties. Foam improvers can, if desired, be included in the solutions of surface-active agents, for example cellulose ethers, alkali carboxymethyl celluloses, polyalkylene oxides, polyalkylene glycol's, hydrolysed proteins, solubilised glues and synthetic non-fluoro chemical surface-active agents and foam boosters. In the use of foams against fires a concentrated solution of the surface-active agents and foam improvers is often diluted at the site of the fire using any convenient water supply available. Any of the foamable compositions disclosed herein may be diluted with any natural water including sea water.

In preparing foams the oligomer-based surface-active agents are conveniently used in aqueous solutions at concentrations of 0.10^ to 5f by weight, preferably 0,25^ to 1.0?*, of the composition immediately prior to foaming. A convenient concentration of foam improver is ϋ.05^ to ~L,Cf by weight of the composition prior to the concentration being less than the oligomer based surfactants foaming. To generate the foam the solution may be blown with a non-inflammable gas, for example nitrogen or a fluorocarbon propellant, or merely agitated for example by a rotary propeller or whisk. The invention is not restricted to these ranges because concentrated solutions are often prepared.

In compositions where the oligomer-based surface-active agent is present together with a further agent for producing a fire- fighting foam the other agent may be for example derived from a protein, a modified protein, a hydrophilic macromolecular compound Optionally based upon cellulose) or a synthetic surface-active agent. The further foaming agent when derived from a protein may contain for example glues, stabilised derivatives of albumins or globulins, or hydrolysed derivatives of protein containing materials such as blood, soya bean, or keratin. The further foaming agent when derived mainly from synthetic materials may include for example soaps, ammonium or sodium lauryl sulphate ammonium or sodium lauryl ether sulphates, alkyl benzene sulphonates, alkyl naphthalene sulphonates and may be fire-fighting formulations based on any of these materials.

Foams made from many of the macromolecular coaipounds hereinbefore described, for example protein derivatives, are often relatively stiff but they can be rendered more mobile by the presence of another surface-active agent, and if the other surface- active agent is a compound based upon oligomers of tetrafluoro ethylene as exemplified herein the fire-fighting properties of the foams are improved.

The foaming agent not derived from branched oligomers of tetrafluoroethylene is often used for fire-fighting purposes at a concentration in water of between 0fcl$? to 6.O by weight usually at between 0.51^ and .57': by weight of the foaming ingredient when that agent is based on a protein,.

Surface-active agents based upon tetrafluoroethylene oligomers accox-ding to this invention may be added to the aqueous solution prior to foaming at a concentration of between 0.001 and 0.1/' preferably between 0.01/^ and 0.C3/' by weighte Compositions which are concentrated forms of these solutions with or without water may be prepared ready for dilution with water prior to generating the foam« Examples of the surface-emotive agents which improve the properties of non-fluorocarbon-based fire-fighting foams include the compounds + Na C6¾C¾C0° C6P15CH2COO + i ^ When the non-fluorocarbon-based foaming agent is derived from a protein or a modified protein the surface-active agent added preferably contains an anionic group attached to the tetrafluoroethylene oligomer residue, for example an. anionic group such as cioFi9oc6V°3 C,F ,CILS00 or In the foamable compositions comprising an oligomer-based surface-active agent and a further agent conventionally employed in making fire-fighting foams, that further agent may contain a fluorocarbon chain not derived from branched tetrafluoroethylene oligomers. These fluorochemical agents are usually derived from compounds containing straight-chain or substantially straight-chain perfluoroalkyl groups of -+.-32 carbon atoms in length for example derived from perfluorooctanoic acid, and ^-trifluoromethyl perfluoro-n-octanoic acid.

The total concentration, of fluorochemical surface-active agents in the aqueous composition that is to be foamed is suitably from 0.1^ to 5?; by weight preferably 0, 25f' : to 1.0^ but concentrated solutions up to 5Qf may be prepared suitable for dilution. The weight ratio in -the mixture of those agents vrhose molecules are derived from tetrofluoroethylene oligomers to those agents Λ?ηο8β molecules have ?luorocJ-kyl groups no^ derived from branched tetra- iioneti 'lene aligners is from 100:1 to 1:1 preferably from 20:1 to 5:1.

The foams containing surface-active agents derived from branched tetrafluoroethylene oligomers described herein are observed to possess improved properties valuable for fire-fighting purposes. In addition to the improvements in the mobility of the foam imparted by the oligomer-based surface-active agent, striking improvements in the ability of the foam to resist flames has been observed. Also the foaming power of many foaming agents used in fire-fighting is severely impaired by the presence of petrol or other hydrocarbon fuel particularly hot or burning petrol. The foams and foamable compositions of this invention possess particularly good petrol tolerance and therefore show greatly improved fire-fighting performance against petrol fires compared with other foams which do not contain any fluorochemical.

The foams and foamable compositions disclosed herein are also compatible Yf h dry chemical fire-extinguishing agents for example fire-extinguishing compositions which include sodium bicarbonate, potassium bicarbonate, ammonium phosphate, potassium chloride, potassium sulphate or the fire-extinguishing comoositions which Pat. No.1, 168, 092 * are the subject of our U.K. ^Φ^ϋit The dry powder extinguishing agents often do not prevent reignition of hot solids in a fire and the foams of this invention may be applied to blanket the hot solids and prevent possible reignitione Thus foams containing tetra luoroethylene oligomer-based surface-active agents, either as main constituent or as a secondary modifying constituent to other foams, form a useful supplementary fire-fighting system to the attack with clry powder extinguishing agents.

The invention is illustrated but not limited by the following examples in which the parts and percentages are by weight unless otherwise stated.

Examples The evaluation of surface-active agents derived from tetra-fluoroethylene oligomers for use as, or additives to, fire-figkting foams was conducted by assessing the following five properties of the test foam: (i) foaming power and foam stability (ii) ability to resist flames (iii) mobility of foam and re-seal properties (iv) tolerance to petrol (v) compatibility with finaly-divided fire- extinguishing dry powders (a) The foaming power and foam stability were evaluated by measuring the "quarter drainage time" (the time in seconds required for 2jo of the original liquid content of a foam, made by foaming 100 ml of solution to an expansion of 8 times, to drain away and collect as liquid at the base of the foam). (b) Ability to resist flames was measured by determining "bum-back time", (the time in seconds required for a given volume of foam exposed to a petrol flame to break down or disappear). The apparatus for measuring the "burnback time" consists of an 8-inch diameter circular brass dish 2 inches deep divided into two equal compartments by a vertical partition located along a diameter.

The upper edge of the partition is in the same plane as the rim of the dish but its lower edge terminates above the bottom of the dish. 500 ml petrol are poured into the dish and one compartment is then filled evenly with a layer of foam on the petrol up to the rim. The petrol in the other compartment is set alight; one thus has a fixed volume of foam exposed to an approximately constant source of heat. The time taken for the foam to disappear completely and the petrol to burn freely in both compartments is the "burnback time", (c) The mobility of the foams was assessed by visual observation, and also by comparing the shear strength of foams prepared under identical conditions,, (d) The tolerance to petrol was assessed partly by observing performance in the ''burnback" test, when an improved "burnback time" indicated an improved tolerance to heat and hot fuel.

See also test (f) below. (e) Compatibility of foams generated from fluorochemicals alone,with finely-divided fire-extinguishing powders is measured empirically by sprinkling 3g. of sodium bicarbonate surface-treated with compounds known to the art, for example stearates, palmitates and silicones, on to 36 sq. inches of foam and observing whether or not the foam collapses. See also test (g), (f) The petrol tolerance was also measured by the following test.

The foam was injected into the base of a column of petrol 6 inches to 12 inches in height and passed through the petrol in a turbulent manner picking up petrol as it ascended. The foam arriving at the surface of the petrol contained some petrol at a concentration depending on the height of column through which the foam had risen. The contaminated foam was collected and divided into two portions. (i) One portion was poured into a -inch diameter steel pan, and a flame was held near the surface of the foam and the burning characteristics noted.

A, (ii) The other portion was frozen, powdered in a mortar, and allowed to warm up, the petrol and water phases separated, and the % petrol measured. (g) Ability to resist flames with and without dry powder extinguishing agents -was assessed by measuring the time for the foam to be destroyed in the following manner, referred to as the "Indoor Powder Compatibility Test", 350 cc of a motor grade petrol were placed in an open-top steel pan having dimensions 10-inch x 5-inch x 2-inch deep containing a vertical gauze screen located 1-inch from one side of the pan and extending from the base of the pan vertically. The partition was made of 16 mesh steel gauze.

The foam for test was poured into the large compartment, lOg of a fire-extinguishing powder were then sifted on to the foam surface. The petrol was ignited and the time for complete foam destruction was recorded as the "burnback time". The procedure was repeated but no powder was added and the time measured again for complete foam destruction. (h) A U.K. Ministry of Defence Test (Specification DEP 12+.20) was also used to demonstrate the general fire-fighting efficiency of foams. 8 oz of powder are distributed over the surface of gallons of petrol contained in a tray 3-ft diameter and I-inch deep. The petrol is ignited and allowed to burn for 60 seconds before application of the foam at a rate of 0,35 gallon liquid per minute (0.05 gal/sq,ft./min). The foam of expansion ratio 8 is produced from a solution of protein concentrate (equivalent to 1<¾ protein). It is discharged from a 9/32-inch diameter nozzle placed 8-ft from the centre of the fire, and is directed to fall into the centre of the tray.

Three radiometers are placed round the fire to measure the radiation intensity. The fire is considered to be controlled when its intensity is reduced to lOfe of the value shown at the end of the 60-second preburn. (j) Re-sealing properties in the presence of oligomer-based surfactant were demonstrated by the following test. t At the conclusion of the test outlined above, a small area of fuel (approx. 6-inch x 6-inch) was exposed by opening the foam blanket. The fuel was reignited, and the foam blanket spread across the exposed fuel extinguishing the flames. This did not occur in the absence of the oligomer-based surfactant.

Example 1 Several surface-active -agents derived from tetrafluoro-ethylene oligomers were prepared as 0,25% "by weight aqueous solutions and results obtained for fire-fighting properties as shown in Table 1. Hydroxypropyl cellulose was added to some of the solutions as detailed in Table 1 at a concentration of 0.05 by weight.

Table 1 Example 2 Tables 2 and 3 show the results of fire-fighting evaluation tests for surface active agents added to a 2$ protein foam. The concentration of fluorine compound was 0,02 by weight.

Table 2 Table 3 Petrol^Tolerance Test (f) Table - Indoor Powder Compatibility Test (g) * Petrol containing lO^o industrial methylated spirits Table 5 General Fye-Fighting Bfficiency Tests ( ) and (,i e 3 The results of fire-fighting tests on foams made from 0.25 aqueous solutions of the surface-active agent together vith a foam improver are shown in Table 6.

The effect of the same surface-active agent at a concentration of 0.02/2 on a 1.3$ protein foam is shown in Table 7· Table 6 Table 7 jTest (a) Quarter Bunback Foam prainage Time Time (mins) (mins) Protein 10 1.5 Protein + C(C 5)S0~ il 7 3.0 Table 8 Petrol Tolerance Test (f) Table 9 Indoor Powder Compatibility Example 4 suits of fire-fighting tests of foams made from 0.25;$ aqueous solutions of surface-active agents of the general formula CgP^CH2C0- are shown, in Table 10. A foam improver, hydroxypropyl cellulose was included as indicated by the concentrations shown in Table D.

The effect of 0.02 by weight of the same surface-active agents on a 1,3% protein foam is shown in Tables 11, 12 and 13.

Table 10 0*25% Aqueous Solutions Table 11 Table 12 Petrol Tolerance Test (f) Petrol Foam Pickup Burning Characteristics l«3/« Protein alone 10 Burns readily, extinguished 20 sees. tl 30 " burnt to destruction " + 0.02 C2F5)2(GF3) 10 Difficult to ignite, extinguished GCHgCOO Na 0 sees. fi it ti tt it , 50 " " " I sees.

Table 13 Indoor Powder Compatibility Test (p) Example 5 A protein solution (l»3- "by weight) was foamed with and without an added concentration of by weight of each of the surface-active agents and test (c) was applied to each foam separately.

The foamed protein solution without added surface-active agent gave a sti f foam with poor ability to flor. The foams prepared from the protein solution containing 0.02^ by weight of the surface-active agents were less stiff and flowed more readily. The shear strength of the protein foam was approximately three times the shear strength of the protein foams containing the fluorochemical surfactants.

Example 6 Compositions -trere prepared containing mixtures of the two surface-active agents one containing a straight perfluoroalkyl chain as follows: (i) 05? of O^F^OCgH^SO" Na > of n-C7P15CONEi(CH2)3N+(CH5)5l" all percentages by weight.

Both mixtures had good compatibility with finely-divided sodium bicarbonate treated with knovm free-f la»ving agents, for example silicones or stearates. Quarter drainage times (a) and bumback times (b) were measured for aqueous solutions containing 0.02^ by weight of the mi ture and 0.05> by weight of a hydroxypropylcellulose as foam improver. The results are presented in Table V Table V+ Test (a) Test (b) Quarter Burnback Time Drainage Surface-active Agent (sees) Time (sees) Composition (i) ¾0 50 Composition (ii) 120 195 n-C-J115C0NH (CH2 ) ^ (CH^ ) ^ ^E^OO" 2 Ο 225 420 . 390

Claims (1)

1. 2. What claim A method of producing a foam which comprises foaming an aqueous composition comprising a agent derived from a branched oligomer of n is an integer equal at least to A method as claimed in Claim 1 wherein the agent is derived from the pentamer or of A method as c laimed in Claim 1 or Claim 2 wherein the agent contains branched perfluoroalkenyl A method as claimed in Claim 1 or Claim 2 wherein the agent contains branched A method as claimed in Claim 1 or Claim 2 wherein the agent contains at least one hydrogen atom attached to a carbon atom of a radical originating from the tetrafluoroethylene A method as claimed in Claim wherein the agent is a sulphonic acid derived from the pentamer and having the forjnula or is a salt of the said A method as claimed in Claim 6 wherein the salt is the sodium or potassium A method as claimed in Claim wherein the agent is a sulphonamide derived from the having the formula is hydrogen or an 2 group and R is a hydrophilic A method as claimed in Clafun wherein the agent is derived from the pentamer and has the formula wherein Q is a hydrophilic A method as claimed in Claim 9 wherein the agent is a carboxylic acid derived from the pentamer and having the formula or a salt of the said A method as claimed in Cla im 10 wherein the salt is the or potassium A method as claimed in Claim 9 wherein is the group wherein m is an integer from 1 to 6 Y and which may be the same or are methyl or ethyl and is an anion derived from a quatemisation A method as claimed in Claim 9 wherein is the group A method as claimed in Claim wherein is the group where L is a methyl or ethyl group and A is an atom of bromine or A method as claimed in Claim 9 wherein is the group where z is from 1 to Z j A method as claimed in Claim 3 wherein the agent is a perfluoroallcenyloxybenzene parasubstituted derivative 20 having the formula R is a hydrophilic group and n is 5 or A method as claimed in Claim 16 wherein R is a group where is a hydrogen an alkali metal 25 an ammonium group or a tetraaliyl ammonium A method as claimed in Claim 17 wherein is a sodium atom or a potassium A method as claimed in Claim 16 wherein R is a group where ra is an integer from 1 Y and which may be the same or are methyl or ethyl groups and A is an A method as c laimed in Claim wherein A is an of bromine or A method as claimed in Claim 19 wherein the agent is A method as claimed in 16 wherein R is the group A method as claimed in 16 wherein R is a group where L is an alkyl group and M is a hydrogen an alkali metal an ammanium group or a tetraalkyl ammonium A method as claimed in Claim 23 wherein R is the group where M is an atom sodium or A method as claimed in Claim 3 wherein the agent is a derivative of the formula where n is 5 or Y and which may be the same or methyl or ethyl and A is an A method as claimed in Claim 25 wherein A is an atom of bromine or A method as claimed in Claim 26 wherein the agent is where X and which be the same or different are a methyl or ethyl groups and A is a atom or an iodine A method as claimed in Claim 3 wherein the agent is a compound of the formula n is or 6 and R is a radical derived from a diamine or a A method as claimed in Claim 28 wherein R is a group where m is an integer from 1 m to 6 Y and which may be the same or are methyl or ethyl and is an A method as claimed in Claim wherein A is an atom of bromine or A method as claimed in Cla im 30 wherein the agent is A method as claimed in Claim 28 wherein R is a group where m is an integer from 1 to 6 and L is an A method as claimed in Claim 32 wherein R is the group A method as claimed in Claim 28 wherein R is a group where z is from 1 to A method as claimed in any of the preceding claims wherein the total concentration of agent is from to by weight of the aqueous A method as claimed in Clairi 35 wherein the total concentration of the agent is from to by weight of the aqueous A method as claimed in any of the preceding claims wherein the aqueous composition also comprises a foam A method as claimed in Claim 37 wherein the foam improver is hydroxypropyl cellulose or polyethylene A method as claimed in 3. Claim 37 Claim wherein the concentration of foam improver is from to by weight of the aqueous A method of producing a foam as claimed in Claim 1 and substantially as described A whenever made by a method claimed in any of the preceding A foamable aqueous composition comprising at least one agent having a formul as defined in Claim 16 or in any Claims 19 to 0 or 32 to A composition as claimed in Claim 42 wherein the total concentration of agent is from weight of the aqueous A composition as claimed in Claim 43 wherein the total concentration of agent is from by weight of the aqueous A composition comprising at least one agent derived from a branched oligomer of ethylene is an integer equal at least to and at least one further not derived from a branched oligomer for producing a A composition as claimed in Claim 45 wherein the further agent is an agent based upon a protei or modified composition A as claimed in Claim 45 wherein the further agent is a compound containing from 4 to 12 carbon A composition as claimed in Claim 45 wherein the further agent is a derivative of acid sulphonic A composition as claimed in either of Claims 47 or the weight ratio of those agents derived from branched oligomers to those further agents not derived from branched oligomers is from to A composition as claimed in 4. Claim 49 wherein the weight is from 5 to 20 5 A oompesition as claimed in any of Claims 45 to 50 wherein the agent derived from a branched is a compound as defined in any of Claims to A composition as claimed in any of Claims 45 to 50 wherein the agent derived from a branched oligomer is a compound as defined in Claim or in any of Claims 9 to 1 A composition as in any of Claims 45 to 50 wherein the agent derived from a branched oligomer is a compound as defined in Claim or in any of Claims l6 to A oomposition as claimed in any of Claims 45 to 50 wherein the agent derived from a branched oligomer is a compound as defined in any of Claims 28 to A composition as claimed in any of Claims 45 to 54 which also comprises A composition as claimed in Claim 55 which is an aqueous composition ready for A method of producing a foam which comprises foaming an aqueous composition as claimed in Claim 5 A composition as claimed in Claim substantially as described A composition claimed in 5. Claim 5 and substantially as shown in the A method of fighting a fire which comprises applying to the a produced from an aqueous composition as defined in any of Claims 1 to A method of fighting a fire which comprises applying to the fire a foam produced from an aqueous composition claimed in Claim insufficientOCRQuality