Compositions – Fire-extinguishing – Foam or gas phase containing
Reexamination Certificate
2000-01-18
2002-08-20
Toomer, Cephia D. (Department: 1714)
Compositions
Fire-extinguishing
Foam or gas phase containing
C528S328000, C162S066000, C427S411000, C252S002000
Reexamination Certificate
active
06436306
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to novel perfluoroalkyl-substituted amino acid derivatives and their use in water dispersible polymeric foam stabilizers for aqueous, alcohol-resistant, polar fire fighting foam formulations (AR-AFFF), and for textile and paper oil-proofing finishes. More particularly it relates to oligomers or copolymers of an aliphatic diamino acid with 3 to 10 carbon atoms such as lysine with a chain extender and having at least two perfluoroalkyl groups attached to nitrogen atoms.
BACKGROUND OF THE INVENTION
Aqueous Fire-Fighting Foam (AFFF) formulations contain water-soluble fluorosurfactants along with hydrocarbon surfactants. They are effective in extinguishing non-polar solvent fires. When an AFFF formulation comes in contact with a burning hydrocarbon fuel, the water, which contains both fluoro- and hydrocarbon surfactants, drains from the foam and forms a thin film on top of the burning fuel. This film does not sink, but due to its low surface energy (<18 dynes/cm, which is lower than that of heptane), it spontaneously spreads across the surface of the burning fuel. There it acts as a vapor suppressant and, in combination with the aqueous foam, extinguishes the fire and prevents reigniton of the fuel. It is important in this application that the foam have a long foam life on the hot fuel; otherwise the fuel can reignite, an event called bumback. A long foam life which provides bumback resistance is achieved by having a foam which is “wet”, that is hydrated, and from which water can drain down onto the surface and replenish the seal. On a non-polar fuel like gasoline, this task is simple since water and the water-soluble surfactants are not soluble in the fuel.
This task is considerably more difficult on polar fuels like isopropanol and acetone. Besides the fluoro- and hydrocarbon surfactants found in conventional AFFF formulations, an Alcohol-Resistant (=AR) AFFF formulation contains a water-soluble but polar-solvent insoluble fluorochemical—also referred to as “alcoholophobic”—foam stabilizer (as described in this invention) along with a polysaccharide such as xanthan gum. When these additional materials come in contact with a burning polar fuel fire, they precipitate and give rise to a membrane which protects the foam from dissolving in the polar solvent. This membrane creates a vapor barrier which extinguishes the fire and prevents reignition of the fuel along with keeping the foam hydrated.
Polysaccharides and/or high molecular weight synthetic polymers may be used in AR-AFFF formulations without a fluorochemical foam stabilizer and provide about the same efficacy. The problem with a foam concentrate containing only polysaccharides and/or high molecular weight synthetic polymers is that its viscosity is high, and the concentrate behaves in a thixotropic manner. It is difficult to use a high viscosity foam concentrate since it is hard if not impossible to pump it through a fire nozzle. AR-AFFF formulations containing fluorochemical foam stabilizers require much lower amounts of polysaccharides and/or high molecular weight synthetic polymers, thus lowering the viscosity of the foam concentrate. Additionally, foam concentrates containing fluorochemical foam stabilizers in AR-AFFF formulations tend to behave in a Newtonian manner.
Fire fighting foam stabilizers containing at least one perfluoroalkyl group and water-solubilizing functionalities such as carboxy and amido groups are described in U.S. Pat. Nos. 4,460,480 and in 5,218,021.
French patent application 2,637,506-A describes an alcoholophobic and oleophobic fire extinguishing foam concentrate which contains a polyhydroxy-polyamine containing at least one quaternary N atom and/or a polysaccharide which is chemically bonded to highly fluorinated C
4
-C
20
alkyl groups, instead of containing the fluorosurfactant and the polysaccharide or other alcoholophobic agent separately in the concentrated mixture.
Alcoholophobic fire fighting foam stabilizers containing at least one perfluoroalkyl group along with poly-quatemary ammonium and carboxy functionalities are described in world patent applications WO 90/02110 A1 and WO 90/03966 A1 along with publications by S. Szönyi in Fire Safety Journal, 16, pp. 353-365 (1990) and Progress in Colloid & Polymer Science, 81, 136-139 (1990).
Since quatemary ammonium groups cause incompatibility with the anionic surfactants used in fire fighting formulations, further improvements have been described in WO 94/18245. This reference teaches compounds which contain a combination of at least two perfluoroalkyl groups, amino groups other than quaternary ammonium groups, carboxylic groups and other water-solubilizing groups attached to amino groups.
S. Szönyi, Corn. Joum. Com. Esp. Deterg., 22, pp.297-304 (1991) a refers to a commercial state-of-the-art alcoholophobic foam stabilizer, MX30, as a perfluoroalkylated polyamino acid. However, from the various Szönyi references discussed above it appears that MX30 is a polyamine derivative with perfluoroalkyl and COOH groups attached to amino nitrogens via a linking group.
U.S. Pat. No. 4,606,973 discloses aminoethylmethacrylate-acrylic acid copolymers in which the amino groups have been reacted with perfluoroalkyl carboxylic acids.
Japanese patent application S59-230566 describes foam stabilizers useful for polar solvents which contain an anionic or amphoteric fluorosurfactant, polyethylenimine of MW 4,000 to 100,000, and a polybasic acid compound.
U.S. Pat. No. 3,769,307 claims perfluoroalkylsubstituted polyethylenimine compositions and the preparation thereof. This patent also claims the use of such compounds as textile finishes providing oleophobic properties. German Offenlegungsschrift 2 018 461 describes surface-active agents and foam stabilizers for polyurethane foams which are polyethylenimines substituted by one or more perfluoroalkyl groups, as well as perfluoroalkyl-substituted polyamines containing up to 16 carboxy or sulfonic acid groups and/or hydrophilic amide groups. Although not directed toward foam stabilizer compounds for polar solvent fire fighting foams, the composition of this patent is described as very soluble in alcohol/water mixtures, but poorly soluble in alcohol (=“alcoholophobic”) and water itself, making it a candidate for such foam stabilizers. Indeed, the above-mentioned WO 94118245 reference describes the synthesis of a perfluoroalkyl- and carboxy-substituted polyethylenimine from tetraethylene-pentamine, a perfluoroalkyl acyl chloride and chloroacetic acid.
U.S. Pat. No. 5,750,043 also describes foam stabilizers containing polyamines wherein the amino groups are partially or completely substituted by perfluoroalkyl groups as well as hydrophilic groups, such as carboxy groups.
Effective foam stabilizers on polar solvents have to be essentially insoluble in these solvents. Most commonly used are polyamines which are N-substituted by perfluoroalkyl and carboxy groups, such as those described above. The present invention discloses a new class of poly-perfluoroalkyl- and carboxy-substituted amines in which the carboxy groups are attached to a carbon atom and which are the reaction products of oligomers or copolymers of an aliphatic diamino acid having 3 to 10 carbon atoms, such as lysine, a chain-extender such as epichlorohydrin, a dihalide or an aliphatic diepoxide, an amino-reactive allyl compound, and a perfluoroalkyl iodide.
A class of non-polymeric amphoteric compounds which contain R
F
-, acid and amino groups, and which are useful to impart oil repellency to paper products are di-R
F
-ramino acids obtained by reaction of an amino acid, allyl glycidyl ether and an R
F
-iodide as described in U.S. Pat. No. 5,491,261. However, these compounds are not oligomers or polymers.
It has now been discovered that by a similar synthetic route, polymeric R
F
-amino acids of the type which are useful as foam stabilizers for polar solvent fire-fighting foams, and which contain a plurality of R
F
groups as well as amino, and carboxy or other hydrophilic groups, can conveniently
Ciba Specialty Chemicals Corporation
Mansfield Kevin T.
Toomer Cephia D.
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