EP0621057A1 - Emulsifier for portable fire extinguishers - Google Patents

Abstract

An emulsifier according to the invention consists of an aqueous solution containing by weight: (a) 1 to 15% of at least one fluorinated betaine (b) 1 to 20% of at least one fluorinated amine oxide (c) 2 to 8% of at least one alkyl glucoside (d) 2 to 10% of at least one other anionic, non-ionic or amphoteric hydrocarbon surface-active agent (e) 20 to 50% of at least one mono-or diethylene (or propylene) glycol monoalkyl ether, the content of fluorinated compounds (a) and (b) being between 5 and 25% and the weight ratio (a + b)/(c + d) being between 1 and 2.

Description

The present invention relates to the field of fire extinguishing and more particularly relates to foam concentrates for portable water spray extinguishers.

One of the well-known means for extinguishing fires of hydrocarbon liquids consists in projecting onto the hearth a foam obtained by mixing under high pressure water and an emulsifier based on surfactants. Most foam concentrates available on the market can be divided into two main categories depending on the nature of the foaming base. In a first family of foam concentrates, the foaming base generally consists of a hydrolyzate of animal proteins (hair, horns, hooves, hemoglobin). To this protein base can be added fluorosurfactants to obtain a fluoroprotein foam concentrate; such emulsifiers are described, for example, in patents GB 1,280,508, GB 1,368,463, US 4,424,133, EP 49,958, US 4,460,480, FR 2,230,384, GB 2,011,784 and WO 8803425.

In the other large family of foam concentrates, the foaming base is composed of a mixture of hydrocarbon-based surfactants. Fluorinated film-forming surfactants can also be incorporated. In the latter type of emulsifiers, known in the art as AFFF emulsifiers, the presence of the fluorinated surfactant makes it possible to produce a foam which, by decantation, forms an aqueous film floating above the surface of the hydrocarbon. The purpose of this aqueous film is not only to extinguish the fire, but also to prevent a possible re-ignition of the surface of the hydrocarbon. Emulsifiers of this type have been described in numerous patents, in particular the following: GB 1 258 299, US 5 085 786, FR 2 347 426, US 3 957 657, FR 2 040 316, US 4 350 206, FR 3 562 156, FR 2 148 442, FR 2 407 724, FR 2 385 413, US 3 772 195, FR 2 397 847, US 3 661 776, US 3 839 425, FR 2 103 669, US 3 957 657, US 3 963,776 and FR 2,296,625.

où

• CE = coefficient d'étalement en mN/m
• γH α = tension superficielle de l'hydrocarbure
• _Ys = tension superficielle de la composition extinctrice après dilution de l'émulseur
• _Yi = tension interfaciale entre l'hydrocarbure et la composition extinctrice après dilution de l'émulseur

In order to obtain good resistance to re-ignition, the foam concentrate after dilution with water and addition of air must produce a foam forming, by decantation, an aqueous film which spreads over the entire surface of the hydrocarbon and with the highest possible thermal stability. The condition of thermodynamic equilibrium necessary to form the aqueous film is linked to the spreading coefficient (CE) which must be positive.

or

• CE = spreading coefficient in mN / m
• γH α = surface tension of the hydrocarbon
• _Ys = surface tension of the extinguishing composition after dilution of the foam concentrate
• _Yi = interfacial tension between the hydrocarbon and the extinguishing composition after dilution of the foam concentrate

Although the spreading coefficient must be positive, care must be taken that the interfacial tension ( _Yi ) is not too low in order to avoid emulsification of the hydrocarbon by the extinguishing composition or too great thinning of the film aqueous. The emulsification of the hydrocarbon by the extinguishing composition risks in fact causing the entrainment of part of the hydrocarbon inside the extinguishing foam, of contaminating the latter and of igniting it.

Another important factor vis-à-vis the re-ignition phenomenon is the thermal resistance of the aqueous film. In this respect, an excessive spreading speed leads to the formation of a very thin film which is not very resistant to heat; conversely, the films most resistant to heat are those with the slowest speed of formation. It is therefore important to find a compromise between the spreading speed and the thermal resistance of the aqueous film, this property being essential for obtaining good resistance to re-ignition. Indeed, the aqueous film which removes the hydrocarbon vapors can at any time, for example by stirring, be separated from the foam from which i is derived and be found directly in contact with an ignited part. If its thermal resistance is too low, the film can be destroyed and release hydrocarbon vapors which ignite immediately and continue to destroy the rest of the film.

AFFF foam concentrates which are generally used with fire hoses are not suitable in a portable extinguisher designed to be carried and used by hand and which, in working order, has a mass less than or equal to 20 kg. In a portable fire extinguisher, the amount of water available to dilute the foam concentrate to the use concentration (0.5 to 6%, most often 1 to 3%) is limited and generally set at 6 or 9 liters , while in the application system by means of a lance the quantity of water available is not limited. Therefore, to meet the certification standards for foaming liquids for hydrocarbon fires, a foaming agent for portable fire extinguisher must be much more efficient than a conventional foaming agent for fire hoses. For example, to obtain the certification of a 6 liter extinguisher for type 144 B fires, the portable extinguisher must extinguish with only 6 liters of foam concentrate solution diluted to 3% (French standard) S61-900), while in the case of extinction with a fire hose the maximum available quantity of foam concentrate solution diluted to 3% may be up to 28.5 liters (French standard S60-220) or 22 , 3 liters (UL 162 standard).

• (a) de 1 à 15 % (de préférence 2 à 12 %) d'au moins une bétaïne fluorée de formule générale :
  
• (b) de 1 à 20 % (de préférence 3 à 15 %) d'au moins un oxyde d'amine fluorée de formule générale :
  
• (c) de 2 à 8 % (de préférence 3 à 6 %) d'au moins un alkylglycoside de formule générale :
  
• (d) de 2 à 10 % (de préférence 3 à 8 %) d'au moins un agent tensio-actif non fluoré anionique, non-ionique ou amphotère autre que ceux de la formule III ;
• (e) de 20 à 50 % (de préférence 30 à 45 %) d'au moins un monoalkyléther de mono- ou di-éthylène (ou propylène)glycol ;

The present invention now relates to an emulsifier for portable fire extinguishers, characterized in that it consists of an aqueous solution containing by weight:

• (a) from 1 to 15% (preferably 2 to 12%) of at least one fluorinated betaine of general formula:
  
• (b) from 1 to 20% (preferably 3 to 15%) of at least one fluorinated amine oxide of general formula:
  
• (c) from 2 to 8% (preferably 3 to 6%) of at least one alkyl glycoside of general formula:
  
• (d) from 2 to 10% (preferably 3 to 8%) of at least one non-fluorinated anionic, nonionic or amphoteric surfactant other than those of formula III;
• (e) from 20 to 50% (preferably 30 to 45%) of at least one monoalkyl ether of mono- or di-ethylene (or propylene) glycol;

the total content of fluorinated compounds a and b being between 5 and 25% (preferably between 7 and 18%) and the weight ratio (a + b) / (c + d) being between 1 and 2 (preferably between 1.3 and 1.7).

• - R_f et R_F, identiques ou différents, représentent chacun un radical perfluoroalkyle, linéaire ou ramifié, contenant au moins 6 atomes de carbone, de préférence de 6 à 16 atomes de carbone ;
• - m et m', identiques ou différents, sont chacun un nombre entier allant de 0 à 6, de préférence égal à 0 ou 2,
• - X et X', identiques ou différents, désignent chacun un groupe CO ou S0₂, de préférence un groupe S0₂;
• - R et R', identiques ou différents, représentent chacun un atome d'hydrogène ou un radical méthyle ou éthyle ;
• - n et n', identiques ou différents, sont chacun un nombre entier allant de 1 à 5, de préférence égal à 3 ;
• - R¹, R^1', R² et R^2', identiques ou différents, représentent chacun un radical méthyle ou éthyle ;
• - p est un nombre entier allant de 1 à 5, de préférence égal à 1 ou 2 ;
• - Y⊖ désigne un groupement SO₃⊖, OSO₃⊖, ou COO⊖;
• - q est un nombre entier allant de 1 à 6, de préférence égal à 1 ou 2 ;
• - R³ représente un radical alkyle, linéaire ou ramifié, contenant de 6 à 18 atomes de carbone, de préférence 8 à 14 atomes de carbone.

In the formulas I, II and III above, the different symbols have the following meanings:

• - R _f and R _F , identical or different, each represents a perfluoroalkyl radical, linear or branched, containing at least 6 carbon atoms, preferably from 6 to 16 carbon atoms;
• - m and m ', identical or different, are each an integer ranging from 0 to 6, preferably equal to 0 or 2,
• - X and X ', identical or different, each denote a group CO or S0 ₂ , preferably a group S0 ₂ ;
• - R and R ', identical or different, each represent a hydrogen atom or a methyl or ethyl radical;
• - n and n ', identical or different, are each an integer ranging from 1 to 5, preferably equal to 3;
• - R ¹ , R ^{1 '} , R ² and R ^2' , identical or different, each represent a methyl or ethyl radical;
• - p is an integer ranging from 1 to 5, preferably equal to 1 or 2;
• - Y⊖ denotes a group SO ₃ ⊖, OSO ₃ ⊖, or COO⊖;
• - q is an integer ranging from 1 to 6, preferably equal to 1 or 2;
• - R ³ represents an alkyl radical, linear or branched, containing from 6 to 18 carbon atoms, preferably 8 to 14 carbon atoms.

dans lesquelles R⁴ représente un radical alkyle, linéaire ou ramifié, contenant de 8 à 18 atomes de carbone, r est un nombre entier allant de 1 à 16, M désigne un ion métallique alcalin ou ammonium quaternaire et M' un ion métallique alcalin.By way of non-limiting example, the non-fluorinated surfactant (d) can be chosen from the compounds of the following formulas:

in which R ⁴ represents an alkyl radical, linear or branched, containing from 8 to 18 carbon atoms, r is an integer ranging from 1 to 16, M denotes an alkali metal ion or quaternary ammonium and M 'an alkali metal ion.

As nonlimiting examples of monoalkyl ethers (e), there may be mentioned the monoethyl or monobutyl ether of ethylene glycol and the monobutyl ether of diethylene glycol, the latter being preferred.

• - comme constituants (a), un mélange de bétaïnes fluorées de formule :
  
  
  dans laquelle x est un nombre entier pair allant de 6 à 16, la teneur du mélange en bétaïne à radical C_sF₁₃ étant d'au moins 50 % en poids;
• - comme constituant (b), l'oxyde d'amine fluorée de formule :
  
• - comme constituant (d), un amido éther propionate de formule (IV-6), un alkyl (3-iminodipropionate de formule (IV-8) ou une alkylamidopropylbétaïne de formule (IV-10).

More particularly preferred emulsifiers are those which contain:

• - as constituents (a), a mixture of fluorinated betaines of formula:
  
  
  in which x is an even whole number ranging from 6 to 16, the content of the mixture of betaine with C _s F ₁₃ radical being at least 50% by weight;
• - as constituent (b), the fluorinated amine oxide of formula:
  
• - As constituent (d), an amido ether propionate of formula (IV-6), an alkyl (3-iminodipropionate of formula (IV-8) or an alkylamidopropylbetaine of formula (IV-10).

The foam concentrates according to the invention can be prepared by simple mixing of the various constituents until homogenization. To accelerate the homogenization, one can operate by heating to a temperature between room temperature and that of boiling of the mixture, preferably at a temperature between 30 and 60 ° C.

The pH of the foam concentrate is advantageously stabilized at a value at least equal to 7 (preferably between 8 and 10) by means of a weak base, for example ammonia or an organic base such as diethanolamine, triethanolamine, urea.

• - un agent antigel comme l'éthylèneglycol ou le propyléneglycol,
• - un co-solvant, par exemple un alcool inférieur (C1 à C4),
• - un anticorrosif tel que le tolyltriazole ou le nitrite de sodium,
• - un conservateur tel que le benzoate de sodium, le fomaldéhyde, l'o-phénylphénol ou le dichlorophène.

If desired, various additives such as:

• - an antifreeze agent such as ethylene glycol or propylene glycol,
• - a co-solvent, for example a lower alcohol (C1 to C4),
• - an anticorrosive such as tolyltriazole or sodium nitrite,
• - a preservative such as sodium benzoate, fomaldehyde, o-phenylphenol or dichlorophene.

The foam concentrates according to the invention can be used in a portable fire extinguisher in an amount of 0.5 to 6 parts by weight (preferably 1 to 3 parts) of foam concentrate per 100 parts by weight of water.

The performance of the foam concentrates according to the invention can be evaluated by the following tests

Spreading test

This test, which indicates the speed of formation of the aqueous film on the surface of the hydrocarbon, is carried out by pouring 50 ml of hydrocarbon (heptane) into a Petri dish (diameter: 11.5 cm), the outer face of which is painted black so that you can watch the film. When the surface is stationary, 0.1 ml of a 3% aqueous emulsifier solution is deposited using a micropipette. The solution should be applied dropwise starting from the center and making an eccentric movement. The stopwatch is started when the first drop is deposited and stopped when the film has covered the entire surface of the hydrocarbon. We note the time. If the total recovery is not obtained in less than a minute, the percentage of surface covered after one minute is noted.

The spreading is satisfactory if the total recovery is obtained in less than 30 seconds, preferably between 5 and 25 seconds.

Thermal resistance test

The evaluation of the thermal resistance of the aqueous film is obtained by measuring the Limit Temperature of Film Stability (TLSF). This test, which can only be carried out if the entire surface of the hydrocarbon is covered by the film, is carried out in a brass measuring container with a diameter of 6.5 cm and a total volume. 100 ml, placed on a thermostated heating plate. In this container, 80 ml of hydrocarbon (heptane) are poured and, when the surface is stationary, 0.1 ml of an aqueous solution of 3% foam concentrate is deposited therein as indicated for the spreading test. After 60 seconds, the end of a thermometer is placed in contact with the aqueous film and a flame about 1 cm above the film. The thermostat is set for a temperature increase of 4 ° C / min. The temperature (TLSF) at which the ignition of the hydrocarbon occurs is noted.

A good foam concentrate should lead to a TLSF higher than 35 ° C, preferably higher than around 40 ° C

Spreading

The overrun (or expansion rate) is the ratio of the volume of foam produced from a 3% aqueous solution of foam concentrate to the initial volume. To determine the overrun, 100 ml of 3% aqueous emulsifier solution is introduced into a 1 liter test tube, then the solution is beaten for one minute at the rate of one beat per second using a perforated circular piston (30 holes of 5 mm in diameter representing 25% of the surface) and fixed in its center to a metal rod.

A satisfactory foam concentrate must lead to an expansion at least equal to 8.

Surface and interfacial tensions

The surface tension (y _s ) with tap water and the interfacial tension (γ) with heptane are measured using a LAUDA tensiometer in accordance with ISO 304 and ISO 6889 standards, but operating at 25 ° C.

• * A = Mélange de bétaïnes fluorées de formule :
  
  
  ayant la composition pondérale suivante:
  
  
  utilisé sous forme de solution aqueuse à 45 %.
• e B = Oxyde d'amine fluorée de formule :
  
  
  commercialisé par la Demanderesse sous forme de solution hydroalcoolique à 40 %.
• •C = Alkyl (C₈ et C₁₀)-glucoside commercialisé sous forme de solution aqueuse à 70 % par la Société UNION CARBIDE sous la dénomination Triton BG 10.
• • D1 = Alkyl (C₈ et C₁₀) amidoéther propionate de formule :
  
  
  commercialisé sous forme de solution aqueuse à 50 % par la Société REWO sous la dénomination Re- woteric AMVSF
• • D2 = N-lauryl-β-iminodipropionate de formule :
  
  
  commercialisé en solution aqueuse à 30 % par la Société HENKELsous la dénomination Deriphat 160C.
• • D3 = Alkyl (C₁₂ et C₁₄)-amidopropylbétaïne de formule :
  
  
  commercialisé en solution aqueuse à 30 % sous la dénomination Ampho-tensid B4 par la Société ZSCHIMMER et SCHWARTZ.
• • D4 = Décyl éther sulfate de formule :
  
  
  utilisé en solution aqueuse à 30 %.
• • E = Mono-n.butyléther du diéthylèneqlycol:
  

In the following examples which illustrate the invention without limiting it, the percentages indicated are expressed by weight and the main constituents used are designated, for simplicity, by the following abbreviations:

• * A = Mixture of fluorinated betaines of formula:
  
  
  having the following weight composition:
  
  
  used in the form of a 45% aqueous solution.
• e B = Fluorinated amine oxide of formula:
  
  
  marketed by the Applicant in the form of a 40% hydroalcoholic solution.
• • C = Alkyl (C ₈ and C ₁₀ ) -glucoside sold in the form of a 70% aqueous solution by the company UNION CARBIDE under the name Triton BG 10.
• • D1 = Alkyl (C ₈ and C ₁₀ ) amidoether propionate of formula:
  
  
  marketed in the form of a 50% aqueous solution by the company REWO under the name Rewoteric AMVSF
• • D2 = N-lauryl-β-iminodipropionate of formula:
  
  
  marketed in 30% aqueous solution by the company HENKEL under the name Deriphat 160C.
• • D3 = Alkyl (C ₁₂ and C ₁₄ ) -amidopropylbetaine of formula:
  
  
  sold in 30% aqueous solution under the name Ampho-tensid B4 by the company ZSCHIMMER and SCHWARTZ.
• • D4 = Decyl ether sulfate of formula:
  
  
  used in 30% aqueous solution.
• • E = Mono-n.butyl ether of diethylene glycol:
  

EXAMPLE 1

a) By mixing the appropriate quantities of the abovementioned commercial products at 40 ° C. with moderate stirring, an emulsifier according to the invention is prepared, the active ingredient contents of which are as follows:

• - température de congélation: -22 ± 2°C
• - masse volumique: 1,065
• - viscosité: 18 mPa.s
• - indice de réfraction: 1,414
• -γ_s (3 % eau de ville): 16,4 mN/m
• - γi (3% eau de ville/heptane): 2,5 mN/m
• - point éclair (en coupe fermée): 50 °C

This composition, brought to pH 9.3 by addition of diethanolamine, has the following characteristics:

• - freezing temperature: -22 ± 2 ° C
• - density: 1.065
• - viscosity: 18 mPa.s
• - refractive index: 1.414
• -γ _s (3% city water): 16.4 mN / m
• - γi (3% city water / heptane): 2.5 mN / m
• - flash point (in closed section): 50 ° C

• - étalement: 20 secondes
• - TLSF: 47°C
• - foisonnement: 10,2

Subjected to the tests described above, this foam concentrate leads to the following performances:

• - spreading: 20 seconds
• - TLSF: 47 ° C
• - expansion: 10.2

90 ml of this foam concentrate are placed in the cartridge of a 6 liter portable fire extinguisher, then its effectiveness is tested on a heptane 144 B hearth (standard NF S61-900). The extinction was obtained with excellent behavior in the face of the phenomenon of re-ignition. In fact, if after the extinction the floating aqueous film is broken and ignites the hydrocarbon vapors brought into contact with the air, the film is reformed immediately and completely covers the surface of the hydrocarbon again, thus extinguishing the hearth nascent.

b) By way of comparison, two emulsifiers (b1) and (b2) not in accordance with the present invention were prepared and brought their pH to 8.5 by means of diethanolamine.

Their composition and performance are summarized in the following table:

In the thermal resistance test (TLSF), the foam concentrates (b1) and (b2) prove to be less efficient than the foam concentrate of example 1-a.

EXAMPLE 2

Example 1-a is repeated, but the proportions of the various constituents are modified and / or the surfactant D1 is replaced by the compound D2.

The following table indicates the composition and the performances of three foam concentrates thus obtained.

EXAMPLE 3

The procedure is as in Example 1-a, but a part of the ether E is replaced by monoethylene glycol (hereinafter MEG) and the proportions of the various surfactants are varied.

Four emulsifiers are thus prepared which are brought to pH 8.5 by addition of diethanolamine. Their composition and performances are collated in the following table.

EXAMPLE 4

The procedure is as in Example 1-a, but a part of the ether E is replaced by monoethylene glycol and at least one of the surfactants D2, D3 and D4 is used in place of D1 and / or instead of alkylglucoside C.

• - 5 émulseurs selon l'invention (4a, 4b, 4c, 4d et 4e)
• - 5 émulseurs non conformes (4f, 4g, 4h, 4i et 4j)

qu'on porte à pH 8,5 au moyen de diéthanolamine avant d'effectuer les tests.Ten different foam concentrates are thus prepared:

• - 5 foam concentrates according to the invention (4a, 4b, 4c, 4d and 4e)
• - 5 non-compliant foam concentrates (4f, 4g, 4h, 4i and 4d)

which is brought to pH 8.5 by means of diethanolamine before carrying out the tests.

The composition and performance of these different foam concentrates are gathered in the following table:

Examination of the results shows that in the absence of alkylglucoside (4g, 4h, 4i and 4d emulsifiers) a satisfactory spreading and / or a high TLSF is not obtained, but that this hydrocarbon cosurfactant alone (foam concentrate 4f) leads to insufficient expansion.

Claims (12)

1. Foam concentrate for portable fire extinguishers, characterized in that it consists of an aqueous solution containing by weight: (a) from 1 to 15% of at least one fluorinated betaine of general formula:

in which Rf represents a linear or branched perfluoroalkyl radical containing at least 6 carbon atoms, m is an integer ranging from 0 to 6, X represents a CO or SO _{2 group} , R represents a hydrogen atom or a radical methyl or ethyl, n is an integer ranging from 1 to 5, R ¹ and R ² , identical or different, each represent a methyl or ethyl radical, p is an integer ranging from 1 to 5, and Y ° represents a group SO ₃ ⊖, OS0 ₃ ⁹ or COO⊖; (b) from 1 to 20% of at least one fluorinated amine oxide of general formula:

in which the symbols R _F , m ', n', X ', R', R ^{1 '} and R ^2' respectively have the same general meanings as R _f , m, n, X, R, R ¹ and R ² ; (c) from 2 to 8% of at least one alkylglucoside of general formula:

wherein q is an integer ranging from 1 to 6 and R ³ represents an alkyl radical, linear or branched, containing from 6 to 18 carbon atoms; (d) from 2 to 10% of at least one non-fluorinated anionic, nonionic or amphoteric surfactant other than those of formula III; (e) from 20 to 50% of at least one monoalkyl ether of mono- or di-ethylene (or propylene) glycol;
the total content of fluorinated compounds a and b being between 5 and 25% and the weight ratio (a + b) / (c + d) being between 1 and 2. 2. foam concentrate according to claim 1, characterized in that it contains from 2 to 12% of fluorinated betaine (s), 3 to 15% of fluorinated amine oxide (s) , 3 to 6% of alkyl glucoside (s), 3 to 8% of surfactant (s) other than those of formula III, and 30 to 45% of monoalkyl ether (s) of mono- or di-ethylene (or propylene) glycol. 3. foam concentrate according to claim 1 or 2, wherein the total content of fluorinated compounds is between 7 and 18%. 4. foam concentrate according to one of claims 1 to 3, wherein the weight ratio (a + b) / (c + d) is between 1.3 and 1.7. 5. An emulsifier according to one of claims 1 to 4, in which the radicals R _f and / or R _F contain from 6 to 16 carbon atoms, m and / or m is equal to 0 or 2, n and / or is not equal to 3, p is equal to 1 or 2, q is equal to 1 or 2, and the radical R ³ contains from 8 to 14 carbon atoms. 6. foam concentrate according to claim 5, containing a mixture of fluorinated betaines of formula:

in which x is an even whole number ranging from 6 to 16, the content of the mixture of betaine with radical C _s F ₁₃ being at least 50% by weight. 7. An emulsifier according to claim 5 or 6, in which the amine oxide is the compound C ₆ F ₁₃ -CH ₂ CH ₂ -

8. An emulsifier according to one of claims 1 to 7, in which the non-fluorinated surfactant (d) is chosen from the compounds of formulas:

in which R ⁴ represents an alkyl radical, linear or branched, containing from 8 to 18 carbon atoms, r is an integer ranging from 1 to 16, M denotes an alkali metal ion or quaternary ammonium and M 'an alkali metal ion. 9. foam concentrate according to one of claims 1 to 8, wherein the ether (e) is the monobutyl ether of diethylene glycol. 10. Emulsifier according to one of claims 1 to 9, stabilized at a pH at least equal to 7, preferably between 8 and 10. 11. Emulsifier according to one of claims 1 to 10, further comprising an alcoholic co-solvent, an antifreeze, a preservative and / or an anti-corrosion agent. 12. Use of a foam concentrate according to one of claims 1 to 11 in a portable fire extinguisher, in an amount of 0.5 to 6 parts by weight, preferably 1 to 3 parts, of foam concentrate per 100 parts by weight of water.