Aqueous fire-fighting foams with reduced fluorine content
Aqueous film forming firefighting composition concentrates are provided that contain an effective amount of a monomelic zwitterionic or anionic C 6 perfluoroalkyl surfactant having a molecule weight less than 800 daltons. The compositions also contain an effective amount of a foam stabilizing agent, and an effective amount of at least one non-fluorinated surfactant. The composition has less than 0.8% F, and is substantially free of any surfactant containing a perfluoroalkyl group containing more than 6 carbon atoms. The composition meets Military Specification MIL-F-24385F.
1. An aqueous film-firefighting composition concentrate comprising:
(a) an effective amount of a monomeric C 6 perfluoroalkyl surfactant having a structure represented by the formula I:
R f —X—Y-L-Z I:
wherein R f is C 6 straight or branched chain perfluoroalkyl;
X is C 2 -C 12 straight or branched chain alkylene, or C 2 -C 12 straight or branched chain alkenylene containing 1 or 2 alkene moieties;
Y is selected from the group consisting of:
—S—CH 2 CH(R 1 )CON(R 2 )—, —O—CH 2 CH 2 —N(R 3 )(R 4 )—; —O—CH 2 CH(OR 5 )CH 2 —N(R 3 )(R 4 )—; —O—CH 2 CH(OR 5 )CH 2 —S—; —S—CH 2 CH(OR 5 )CH 2 —N(R 3 )(R 4 )—; and —S—CH 2 CH(OR 5 )CH 2 —S—;
L is C 2 -C 12 straight or branched chain alkylene, where one carbon atom in the chain optionally is replaced by —N(R 6 )(R 7 )—; and
Z is —OSO 3 − , —SO 3 − , or —CO 2 − ,
wherein R 1 , R 2 , R 3 , R 4 , R 6 and R 7 , independently are H or straight or branched chain C 1 -C 6 alkyl, and R 5 is H or straight or branched chain C 1 -C 6 alkyl or trialkylsilyl;
(b) an effective amount of a foam stabilizing agent, and
(c) an effective amount of at least one non-fluorinated surfactant,
wherein said composition has less than 0.8% F, and is substantially free of any surfactant containing a perfluoroalkyl group containing more than 6 carbon atoms and wherein said composition meets Military Specification MIL-F-24385F.
2. The composition according to claim 1 wherein said non-fluorinated surfactant is an anionic surfactant.
3. The composition according to claim 1 , wherein said foam stabilizing agent is a glycol ether.
4. The composition according to claim 1 , further comprising a corrosion inhibitor.
5. The aqueous film-firefighting composition concentrate according to claim 1 ,
wherein said composition does not contain an effective amount of a perfluorinated surfactant that does not conform to formula I.
6. The composition according to claim 1 , wherein Y is —S—CH 2 C(R 1 )CON(R 2 )—.
7. The composition according to claim 6 , wherein R 1 is H or straight chain alkyl and R 2 is H.
8. The composition according to claim 1 , wherein Y is —O—CH 2 CH 2 —N(R 3 )(R 4 )—.
9. The composition according to claim 8 , wherein R 3 and R 4 are H or methyl.
10. The composition according to claim 1 , wherein Y is —O—CH 2 CH(OR 5 )CH 2 —N(R 3 )(R 4 )—.
11. The composition according to claim 10 , wherein R 3 and R 4 are H or methyl, and R 5 is H or trialkylsilyl.
12. The composition according to claim 1 , wherein Y is —O—CH 2 CH(OR 5 )CH 2 —S—.
13. The composition according to claim 12 , wherein R 5 is H or trialkylsilyl.
14. The composition according to claim 1 , wherein Y is —S—CH 2 CH(OR 5 )CH 2 —N(R 3 )(R 4 )—.
15. The composition according to claim 14 , wherein R 3 and R 4 are H or methyl, and R 5 is H or trialkylsilyl.
16. The composition according to claim 1 , wherein Y is —S—CH 2 CH(OR 5 )CH 2 —S—.
17. The composition according to claim 16 , wherein R 5 is H or trialkylsilyl.
18. The composition according to claim 1 or claim 5 , further comprising an alkylpolyglycoside in the amount of 0.3 to 7%.
19. The composition according to claim 1 or claim 5 , further comprising a polysaccharide gum in an amount of 0.1 to 5%.
20. The composition according to claim 5 , comprising a plurality of perfluoroalkyl surfactants of the formula I.
21. The composition according to claim 1 or claim 5 , wherein said foam stabilizing agent is present in an amount of 1-50%, said non-fluorinated surfactant is present in an amount of 0.1 to 30% and said perfluoroalkyl surfactant or mixture of surfactants of formula I is present in an amount of 0.5 to 20%.
22. A fire-fighting foam, comprising a composition according to claim 1 or claim 5 , and an aqueous liquid.
23. The foam according to claim 22 , wherein said aqueous liquid is brackish water or seawater.
24. A method of making a fire-fighting foam, comprising foaming a composition according to claim 1 or claim 5 with an aqueous liquid.
25. The method according to claim 24 , wherein said aqueous liquid is brackish water or seawater.