Fluorine-based surface active agent

Abstract

To provide a perfluoropolyether compound expressing excellent surface tension reduction performance, and expressing excellent foamability and foam stability not only during diluting fresh water but also during diluting sea water, and a fluorine-based surface active agent including the compound.SOLUTION: A perfluoropolyether dicarboxylic acid compound or a salt thereof is expressed by the following formula (1). In the formula, Rf1 represents a 1-4C perfluoroalkyl group. R1 represents a substituted or unsubstituted 1-10C hydrocarbon group. R2 represents a substituted or unsubstituted 1-6C hydrocarbon group. R3 and R4 are same or different and each represent a substituted or unsubstituted 1-4C hydrocarbon group. n is an integer of 0-5.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a fluorosurfactant. [Background technology]

[0002] Fluorosurfactants are additives that have a high surface tension reducing ability and, when mixed with fire extinguishing agents, coating compositions, etc., provide excellent penetration, wettability, leveling, surface functionality, etc., and various types of fluorosurfactants have been proposed to date. In general, fluorosurfactants consist of compounds that have, in the same molecule, a perfluoroalkyl group for realizing surface tension reducing ability and a philic group that contributes to affinity for various compositions.

[0003] Conventional fluorosurfactants have used straight-chain fluorine-containing surfactants with six or more carbon atoms, which have high surface orientation and cohesive properties and can reduce surface tension with a small amount added. However, in response to fluorine regulations, replacement of these surfactants is being promoted.

[0004] Patent Document 1 discloses a betaine surfactant having a perfluoropolyether as a main skeleton. However, the compound described in Patent Document 1 has a drawback in that it has low foaming property and foam stability when diluted with seawater. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 3,839,425 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention provides a perfluoropolyether compound that exhibits excellent surface tension reducing ability and also exhibits excellent foaming properties and foam stability not only when diluted with fresh water but also when diluted with seawater, and a fluorine-based surfactant containing said compound. [Means for solving the problem]

[0007] In order to solve the above problems, the present inventors have conducted extensive research and have found that a perfluoropolyether dicarboxylic acid compound represented by formula (1) exhibits excellent surface tension reducing ability, and also exhibits excellent foaming properties and foam stability not only when diluted with fresh water but also when diluted with seawater.

[0008] The present invention has been completed based on these findings, and includes the following broad aspects. [Section 1] A perfluoropolyether dicarboxylic acid compound or a salt thereof represented by the following formula (1): [ka] (In the formula, Rf1 is a perfluoroalkyl group having 1 to 4 carbon atoms. R 1 R is a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms. 2 R is a substituted or unsubstituted hydrocarbon group having 1 to 6 carbon atoms. 3 and R 4 are the same or different and each is a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and n is an integer of 0 to 5. [Section 2] Item 2. The perfluoropolyether dicarboxylic acid compound or a salt thereof according to item 1, wherein the molecular weight of the perfluoropolyether dicarboxylic acid compound represented by formula (1) is in the range of 400 to 1,700. [Section 3] R 3 and R 4 and are the same or different and are linear alkylene groups having 1 to 4 carbon atoms, or a salt thereof. [Section 4] 4. The perfluoropolyether dicarboxylic acid compound or a salt thereof according to any one of items 1 to 3, wherein n is an integer of 0 to 3. [Section 5] Item 5. A fluorine-based surfactant comprising the perfluoropolyether dicarboxylic acid compound or a salt thereof according to any one of items 1 to 4. [Section 6] Item 5. A composition comprising the perfluoropolyether dicarboxylic acid compound or a salt thereof according to any one of items 1 to 4. [Section 7] Item 5. A coating material comprising the perfluoropolyether dicarboxylic acid compound or a salt thereof according to any one of items 1 to 4. [Section 8] Item 5. A fire extinguishing agent comprising the perfluoropolyether dicarboxylic acid compound or its salt according to any one of items 1 to 4. Effect of the Invention

[0009] According to the present invention, it is possible to provide a perfluoropolyether compound that exhibits excellent surface tension reducing ability, and also exhibits excellent foaming properties and foam stability not only when diluted with fresh water but also when diluted with seawater, and a fluorine-based surfactant containing said compound. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing a presumed mechanism by which the compound of the present invention has excellent foaming properties and foam stability when diluted with fresh water. [Diagram 2] FIG. 1 is a schematic diagram showing a presumed mechanism by which the compound of the present invention has excellent foaming properties and foam stability when diluted with seawater. [Diagram 3] The evaluation criteria for foamability in the examples are as follows. [Figure 4] The evaluation criteria for foam stability in the examples are shown below. [Diagram 5] FIG. 1 is a conceptual diagram showing drainage at the plateau border of a foam. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The perfluoropolyether dicarboxylic acid compound according to the present invention is represented by the following formula (1).

[0012] [ka]

[0013] (In the formula, Rf1 is a perfluoroalkyl group having 1 to 4 carbon atoms. R 1 R is a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms. 2 R is a substituted or unsubstituted hydrocarbon group having 1 to 6 carbon atoms. 3 and R 4 are the same or different and each is a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and n is an integer of 0 to 5. In formula (1), Rf1 is a perfluoroalkyl group having 1 to 4 carbon atoms, and is preferably a linear perfluoroalkyl group having 1 to 4 carbon atoms. The linear perfluoroalkyl group can improve foaming properties and foam stability when diluted with seawater. Examples of the perfluoroalkyl group having 1 to 4 carbon atoms include a trifluoromethyl group, a perfluoroethyl group, a perfluoro-n-propyl group, a perfluoro-isopropyl group, a perfluoro-n-butyl group, a perfluoro-isobutyl group, a perfluoro-sec-butyl group, and a perfluoro-tert-butyl group.

[0014] -(C3F6O) in formula (1) n The -C3F6- in the - moiety may be -CF2CF2CF2-, -CF(CF3)CF2-, or -CF2CF(CF3)-, with -CF2CF2CF2- or -CF(CF3)CF2- being preferred, and -CF(CF3)CF2- being more preferred.

[0015] In the formula (1), -C2F4- in the -C2F4CO- portion may be -CF2CF2- or -CF(CF3)-, with -CF(CF3)- being preferred.

[0016] R 1 is a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms. It is preferably a single bond or a substituted or unsubstituted divalent hydrocarbon group having 1 to 8 carbon atoms, and more preferably a single bond or a substituted or unsubstituted divalent hydrocarbon group having 1 to 6 carbon atoms.

[0017] Examples of the substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms include a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted alkenylene group having 2 to 10 carbon atoms, a substituted or unsubstituted cycloalkylene group having 4 to 10 carbon atoms, a substituted or unsubstituted arylene group having 6 to 10 carbon atoms, and a substituted or unsubstituted aralkylene group having 7 to 10 carbon atoms.

[0018] Preferably, it is a substituted or unsubstituted alkylene group having 1 to 8 carbon atoms, a substituted or unsubstituted alkenylene group having 2 to 8 carbon atoms, a substituted or unsubstituted cycloalkylene group having 4 to 8 carbon atoms, a substituted or unsubstituted arylene group having 6 to 8 carbon atoms, or a substituted or unsubstituted aralkylene group having 7 to 8 carbon atoms, more preferably a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, a substituted or unsubstituted alkenylene group having 2 to 6 carbon atoms, a substituted or unsubstituted cycloalkylene group having 4 to 6 carbon atoms, or a substituted or unsubstituted arylene group having 6 carbon atoms, still more preferably a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, and particularly preferably a (unsubstituted) alkylene group having 1 to 6 carbon atoms.

[0019] Examples of the unsubstituted alkylene group having 1 to 10 carbon atoms include linear alkylene groups having 1 to 10 carbon atoms (e.g., methylene, ethylene, trimethylene, tetramethylene, and pentamethylene); branched alkylene groups having 3 to 10 carbon atoms (e.g., 1-methylethylene, 2-methylethylene, 1-ethylethylene, 2-ethylethylene, 1-methylpropylene, 2-methylpropylene, 1,1-dimethylpropylene, 1-hexylpropylene, 1-hexylbutylene, and 1-octylethylene).

[0020] Examples of the unsubstituted alkenylene group having 2 to 10 carbon atoms include linear alkenylene groups having 2 to 10 carbon atoms (e.g., ethenylene group, propenylene group, etc.); branched alkenylene groups having 3 to 10 carbon atoms (e.g., 1-ethylethenylene group, 1,2-dimethylethenylene group, 1-butylethenylene group, 1-hexylethenylene group, etc.).

[0021] Examples of the cycloalkylene group having 4 to 10 carbon atoms include a cyclobutylene group, a cyclopentylene group, a 2-methylcyclopentylene group, a cyclohexylene group, a 1,3-dimethylcyclohexylene group, a 1-ethylcyclopentylene group, and a cyclohexanedimethylene group.

[0022] Examples of the arylene group having 6 to 10 carbon atoms include an o-, p- or m-phenylene group, a 2,4-naphthylene group, a biphenylene group, and a tolylene group.

[0023] Examples of the aralkylene group having 7 to 10 carbon atoms include a phenylmethylene group, a diphenylmethine group, a 1-phenylethylene group, an o-phenyleneethyl group, and a naphthylmethylene group.

[0024] R 2 are the same or different and are substituted or unsubstituted hydrocarbon groups having 1 to 6 carbon atoms. They are preferably substituted or unsubstituted hydrocarbon groups having 1 to 4 carbon atoms, more preferably substituted or unsubstituted alkyl groups having 1 to 4 carbon atoms, and more preferably (unsubstituted) alkyl groups having 1 to 4 carbon atoms.

[0025] Examples of the hydrocarbon group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an allyl group, a benzyl group, a cyclopentyl group, a cyclohexyl group, and a phenyl group.

[0026] R 3 and R 4 are the same or different and are substituted or unsubstituted hydrocarbon groups having 1 to 4 carbon atoms. They are preferably substituted or unsubstituted divalent hydrocarbon groups having 1 to 4 carbon atoms, more preferably substituted or unsubstituted alkylene groups having 1 to 4 carbon atoms, and more preferably (unsubstituted) linear alkylene groups having 1 to 4 carbon atoms. 3 and R 4 are preferably the same.

[0027] Examples of the divalent hydrocarbon group having 1 to 4 carbon atoms include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a 1-methylethylene group, a 2-methylethylene group, an ethenylene group, and a propenylene group.

[0028] R 1 ~R 4 In the above, when the hydrocarbon group has a substituent, examples of the substituent that replaces a hydrogen atom in the hydrocarbon group include a halogen atom, a hydroxyl group, a thiol group, an amide group, a guanidide group, a nitro group, a cyano group, a dialkylamino group, an alkoxy group, an alkylthio group, an aryloxy group, a halogenated alkyl group (the number of halogen atoms is preferably 1 to 10, more preferably 1 to 7. When the group has a plurality of halogen atoms, they may be the same or different.), an alkylcarbonylamino group, an alkyloxycarbonylamino group, and the like. When the hydrocarbon group has a substituent, the number of the substituents is preferably 1 to 5, more preferably 1 to 3. When the group has a plurality of substituents, the substituents may be the same or different. The compound represented by formula (1) according to the present invention is a dicarboxylic acid compound, and therefore does not include a carboxyl group as a substituent.

[0029] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0030] Examples of the alkyl moiety of the dialkylamino group, alkoxy group, alkylthio group, halogenated alkyl group, alkylcarbonylamino group, and alkyloxycarbonylamino group mentioned above as the substituent include linear or branched alkyl groups having 1 to 12 carbon atoms, such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, 1-ethylpentyl group, heptyl group, octyl group, and 2-ethylhexyl group. The number of carbon atoms in the alkyl group is preferably 1 to 8.

[0031] In addition, the aryl moiety of the aryloxy group exemplified as the above-mentioned substituent includes aryl groups having 6 to 10 carbon atoms, such as a phenyl group and a naphthyl group.

[0032] Also, R 1 ~R 4 In the above, the hydrocarbon group having a substituent may have a divalent group containing at least one heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom between carbon atoms of the hydrocarbon group. The number of heteroatoms may be preferably 1 to 10, more preferably 1 to 6. Examples of the divalent group containing at least one heteroatom include -O-, -N<, -S-, -SO2-, -(C=O)-, -(C=O)O-, -O(C=O)-, -NH(C=O)-, -(C=O)NH-, -NH(C=O)O-, -O(C=O)NH-, etc. When such a divalent group is between carbon atoms of the hydrocarbon group, the hydrocarbon chain is interrupted by this group. In addition, R 1 ~R 4 In the above, such a divalent group is inserted between the carbon atoms of the hydrocarbon group, so that R 1 ~R 4 may have a structure having a hetero ring.

[0033] In formula (1), n ​​is an integer of 0 to 5. n is preferably an integer of 0 to 3, more preferably an integer of 1 to 3, further preferably 1 or 2, and particularly preferably 1. When n is within the above range, excellent surface tension reducing ability is exhibited. When n exceeds 5, the water solubility of the compound represented by formula (1) may decrease. In one embodiment, from the viewpoint of foamability, n is preferably an integer of 0 to 2, more preferably 1 or 2, and particularly preferably 1.

[0034] The molecular weight of the perfluoropolyether dicarboxylic acid compound represented by the formula (1) is preferably 400-1,700, more preferably 500-1,500, and further preferably 600-1,200.

[0035] Specific examples of the perfluoropolyether dicarboxylic acid compound represented by formula (1) include, but are not limited to, the following:

[0036] [ka]

[0037] As the perfluoropolyether dicarboxylic acid compound represented by formula (1), the compounds represented by the above formulas (1-2), (2-1), (2-2) and (4-2) are preferred, and the compounds represented by formulas (2-1) and (2-2) are more preferred.

[0038] In a preferred embodiment, the perfluoropolyether dicarboxylic acid compound represented by formula (1) can be in the form of a salt. Examples of the salt include lithium salt, sodium salt, potassium salt, calcium salt, magnesium salt, ammonium salt, alkanolamine salt, and amine salt. Among these, sodium salt and potassium salt are preferred. By making it into a salt, hydrophilicity can be increased, and stability in water can be increased.

[0039] The perfluoropolyether dicarboxylic acid compound represented by formula (1) of the present invention or a salt thereof can be produced, for example, by a method including the following (Step i) and (Step ii). (Step i) A step of reacting a perfluoropolyether compound represented by the following formula (2) with a diamine represented by the following formula (3) to synthesize an amide compound. (Step ii) A step of reacting the amide compound obtained in (Step i) with an alkyl carboxylic acid compound.

[0040] [ka]

[0041] [In the formula, Rf1 is a perfluoroalkyl group having 1 to 4 carbon atoms. 5is a substituted or unsubstituted hydrocarbon group. n is an integer of 0 to 5.

[0042] [ka]

[0043] [In the formula, R 1 R is a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms. 2 are the same or different and each is a substituted or unsubstituted hydrocarbon group having 1 to 6 carbon atoms.] Rf1 and n in formula (2) are the same as defined in formula (1).

[0044] In formula (2), R 5 is a substituted or unsubstituted hydrocarbon group, preferably a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, more preferably a substituted or unsubstituted hydrocarbon group having 1 to 12 carbon atoms, and particularly preferably a substituted or unsubstituted hydrocarbon group having 1 to 6 carbon atoms.

[0045] Examples of the unsubstituted hydrocarbon group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, an allyl group, a benzyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, and a phenyl group. Preferred are a methyl group, an ethyl group, a tert-butyl group, and a benzyl group, and particularly preferred is a methyl group.

[0046] R 5 In the case where the hydrocarbon group has a substituent, the substituent is R 1 ~R 4 The substituents described above in the above can be used without any particular limitation.

[0047] Specific examples of the perfluoropolyether compound represented by formula (2) include, but are not limited to, the following:

[0048] [ka]

[0049] The perfluoropolyether compound represented by formula (2) can be obtained as a commercial product, for example, CAE-500, CAE-600, or CAE-1000 (all manufactured by Sinochem Corporation).

[0050] R in Equation (3) 1 , R 2 is the same as defined in equation (1). Specific examples of the compound represented by formula (3) include N-methylaminoethylamine, N-methylaminopropylamine, N-methylaminobutylamine, N-methylaminopentylamine, N-methylaminohexylamine, N-ethylaminoethylamine, N-ethylaminopropylamine, N-ethylaminobutylamine, N-ethylaminopentylamine, N-ethylaminohexylamine, N-propylaminoethylamine, N-propylaminopropylamine, N-propylaminobutylamine, N-propylaminopentylamine, N-propylaminohexylamine, N-isopropylaminoethylamine, and N-isopropylamino. Propylamine, N-isopropylaminobutylamine, N-isopropylaminopentylamine, N-isopropylaminohexylamine, N-butylaminoethylamine, N-butylaminopropylamine, N-butylaminobutylamine, N-butylaminopentylamine, N-butylaminohexylamine, N-phenylaminoethylamine, N-phenylaminopropylamine, N-phenylaminobutylamine, N-phenylaminopentylamine, N-phenylaminohexylamine, N-(2-hydroxyethyl)ethylenediamine, N-(2-hydroxyethyl)-1,3-propanediamine, etc. are included, but are not limited thereto. Among these, N-methylaminoethylamine, N-methylaminopropylamine, N-ethylaminoethylamine, N-isopropylaminoethylamine, N-butylaminoethylamine, and N-isopropylaminopropylamine are preferred, and N-methylaminoethylamine and N-methylaminopropylamine are more preferred.

[0051] The step (step i) of reacting the perfluoropolyether compound represented by formula (2) with the diamine represented by formula (3) can be represented, for example, by the following reaction formula.

[0052] [ka]

[0053] In the above reaction formula, Rf1, n, and R in the amide compound represented by formula (4) 1 , R 2 is the same as defined in equation (1).

[0054] In the above reaction, the amount of the diamine represented by formula (3) used is preferably 1 to 2 parts by mol, and more preferably 1 to 1.5 parts by mol, per 1 part by mol of the perfluoropolyether compound represented by formula (2).

[0055] The reaction temperature in the above reaction is usually from 0° C. to 100° C. or the boiling temperature of the solvent.

[0056] The reaction time is usually 1 to 48 hours, preferably 1 to 20 hours.

[0057] Examples of the reaction solvent include methanol, ethanol, isopropanol, tetrahydrofuran, diethyl ether, ethyl acetate, acetonitrile, acetone, methyl ethyl ketone, etc. When a solvent is used, the amount of the solvent used is usually 100 parts by mass or less, preferably 0.2 to 50 parts by mass, per part by mass of the perfluoropolyether compound represented by formula (2). Two or more kinds of solvents can be mixed and used as necessary.

[0058] If necessary, the reaction may be carried out in an atmosphere of an inert gas such as nitrogen, argon, or helium that does not affect the reaction.

[0059] After completion of the reaction, impurities (e.g., unreacted raw materials) can be removed by washing with an organic solvent, the reaction solution can be concentrated, or the like to obtain the amide compound represented by formula (4). If necessary, further purification can be performed using a known method.

[0060] The step (step ii) of reacting the amide compound represented by formula (4) (the amide compound obtained in (step i)) with an alkyl carboxylic acid compound can be represented, for example, by the following reaction scheme.

[0061] [ka]

[0062] In the above reaction scheme, R in formula (5) 3 , R in Equation (6) 4 is the same as defined in equation (1).

[0063] X1 in formula (5) and X2 in formula (6) are the same or different and each represents a leaving group. The leaving group is a group that leaves during a reaction, and includes, but is not limited to, an iodine atom, a bromine atom, a chlorine atom, a methylsulfonyloxy group (-OSO2CH3), a p-toluenesulfonyloxy group (-OSO2C6H5CH3), a trifluoromethylsulfonyloxy group (-OSO2CF3), and the like, with a bromine atom or a chlorine atom being preferred.

[0064] M1 in formula (5) and M2 in formula (6) are the same or different and each represents a hydrogen atom, an alkali metal, an amine base, or an ammonium base. Examples of the alkali metal include lithium, sodium, and potassium. Examples of the amine base include trimethylamine, triethylamine, benzylamine, methylbenzylamine, dimethylbenzylamine, monoethanolamine, diethanolamine, triethanolamine, morpholine, and pyridine.

[0065] The alkyl carboxylic acid compound represented by formula (5) or (6) is preferably a haloalkyl carboxylate. Examples of the haloalkyl carboxylate include, but are not limited to, sodium chloroacetate, sodium 3-chloropropionate, sodium 4-chlorobutyrate, sodium 5-chlorovalerate, sodium bromoacetate, sodium 3-bromopropionate, sodium 4-bromobutyrate, and sodium 5-bromovalerate.

[0066] In the above reaction, the total amount of the alkyl carboxylic acid compounds represented by formula (5) and formula (6) used is preferably 2 to 10 molar parts, more preferably 2 to 5 molar parts, per 1 molar part of the perfluoropolyether compound represented by formula (4).

[0067] The reaction is carried out in the presence of a base, which may include organic bases such as triethylamine, tributylamine, pyridine, 4-dimethylaminopyridine, diazabicyclononene, and diazabicycloundecene, inorganic bases such as sodium hydride, potassium hydride, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and cesium carbonate, alkali metal alkoxides such as sodium methoxide, sodium ethoxide, and potassium tert-butoxide, and organic lithiums such as methyllithium and butyllithium.

[0068] The reaction temperature in the above reaction is usually from 0° C. to 100° C. or the boiling temperature of the solvent.

[0069] The reaction time is usually 1 to 48 hours, preferably 1 to 20 hours.

[0070] Examples of the reaction solvent include water, methanol, ethanol, isopropanol, tetrahydrofuran, diethyl ether, ethyl acetate, acetonitrile, acetone, methyl ethyl ketone, etc. When a solvent is used, the amount of the solvent used is usually 100 parts by mass or less, preferably 0.5 to 50 parts by mass, per part by mass of the perfluoropolyether compound represented by formula (4). Two or more kinds of solvents can be mixed and used as necessary.

[0071] If necessary, the reaction may be carried out in an atmosphere of an inert gas such as nitrogen, argon, or helium that does not affect the reaction.

[0072] After the reaction is completed, impurities (e.g., unreacted raw materials) are removed by washing with an organic solvent, the reaction liquid is concentrated, or the like to obtain a perfluoropolyether dicarboxylic acid compound represented by formula (1). If necessary, further purification may be performed using a known method.

[0073] Moreover, the salt of the perfluoropolyether dicarboxylic acid compound represented by the formula (1) can be obtained by neutralization with various bases such as sodium hydroxide, lithium hydroxide, potassium hydroxide, calcium hydroxide, and the like.

[0074] The perfluoropolyether dicarboxylic acid compound represented by formula (1) or its salt can be used as a fluorosurfactant by itself, but can also be used as a fluorosurfactant (fluorosurfactant composition) which is a composition containing water and / or an organic solvent. The composition may contain one of the perfluoropolyether dicarboxylic acid compounds represented by formula (1) or their salts alone, or may contain two or more of them in combination. As the water, various types of water such as pure water, fresh water, and seawater can be used. As the organic solvent, for example, hexylene glycol, isopropyl alcohol, ethylene glycol, N-methylpyrrolidone, N,N-dimethylformamide, propylene glycol monomethyl ether acetate, methyl ethyl ketone, ethyl acetate, normal butyl acetate, etc. can be used.

[0075] The content of the perfluoropolyether dicarboxylic acid compound represented by formula (1) or a salt thereof in the above fluorosurfactant composition is, for example, about 1 to 60 parts by mass, and preferably about 10 to 50 parts by mass, relative to 100 parts by mass of the total amount of the fluorosurfactant composition.

[0076] The above-mentioned fluorosurfactant composition may be appropriately blended with rust inhibitors, catalysts, antibacterial agents, flame retardants, surfactants, defoamers, thickeners, viscosity regulators, leveling agents, ultraviolet absorbers, preservatives, antifreeze agents, wetting agents, pH adjusters, stabilizers, light resistance stabilizers, weather resistance stabilizers, neutralizers, matting agents, drying accelerators, foaming agents, non-tacky agents, deterioration inhibitors, etc., within the range that does not impair the object of the present invention. These may be used alone or in combination of two or more. Each of these additives may be used within the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the total amount of the fluorosurfactant composition.

[0077] The perfluoropolyether dicarboxylic acid compound or its salt represented by formula (1) of the present invention has excellent surface tension reducing ability, and is therefore useful as a fluorosurfactant. The perfluoropolyether dicarboxylic acid compound or its salt represented by formula (1) preferably has a surface tension of 30 mN / m or less, more preferably 20 mN / m or less, when made into a 0.1% by mass aqueous solution. If the surface tension is 30 mN / m or less, the surface tension reducing ability is excellent. In addition, if the surface tension is 20 mN / m or less, it can be used as a substitute for a linear fluorosurfactant having 6 or more carbon atoms, and therefore is more preferable. In this specification, the surface tension is measured by the Wilhelmy method (liquid temperature 20°C) described in the examples.

[0078] In addition, the perfluoropolyether dicarboxylic acid compound or its salt of the present invention has excellent surface tension reducing ability even at a low concentration, and is therefore useful as a fluorosurfactant. It is preferable that the aqueous solution concentration of the perfluoropolyether dicarboxylic acid compound or its salt represented by formula (1) is 0.1 mass% or less, and the surface tension of the aqueous solution is 30 mN / m or less. It is more preferable that the aqueous solution concentration is 0.05 mass% or less, and the surface tension of the aqueous solution is 30 mN / m or less. If the perfluoropolyether dicarboxylic acid compound or its salt has excellent surface tension reducing ability even at a low concentration, the amount of the fluorosurfactant of the present invention added can be reduced, which is preferable.

[0079] Furthermore, the perfluoropolyether dicarboxylic acid compound or its salt of the present invention has excellent foaming properties and foam stability when diluted with fresh water and seawater. The reason why such effects are obtained is unclear, but the following is assumed.

[0080] It is assumed that the compound of the present invention contains two carboxylic acid groups (anionic functional groups) in the hydrophilic group, and thus intermolecular electrostatic repulsion between the hydrophilic groups is strong. It is also known that the viscosity of the compound of the present invention increases as the concentration of the active ingredient increases, and that the viscosity tends to decrease when the pH is increased or when a metal salt is added. From this, it is believed that intermolecular interactions such as hydrogen bonds are generated. It is believed that such electrostatic repulsion and intermolecular interactions result in higher foaming properties and foam stability when diluted with fresh water compared to monocarboxylic acid compounds (Figure 1).

[0081] In addition, when diluted with seawater, the structure has two carboxylic acid groups (anionic functional groups) in the hydrophilic group, so that it is possible to maintain the amphoteric structure even when it forms an ion pair with the magnesium ions or calcium ions contained in seawater, and it is assumed that this improves foaming properties. Furthermore, the amphoteric structure that forms an ion pair with magnesium ions or calcium ions weakens the electrostatic repulsion between the hydrophilic groups, while allowing the compound of the present invention to densely adsorb to the foam surface, so that a strong foam film with a high fluorine ratio can be formed, and foam stability is thought to be improved (Figure 2).

[0082] The perfluoropolyether dicarboxylic acid compound or a salt thereof, and the fluorosurfactant (fluorosurfactant composition) containing the same of the present invention have excellent surface tension reducing ability as described above, and therefore can be suitably used as an additive for various materials in which aqueous solvents or organic solvents are used, such as paints, fire extinguishing agents, various cleaning agents for industrial and commercial use, coating materials, release agents, etc.

[0083] For example, when the perfluoropolyether dicarboxylic acid compound or its salt of the present invention is used as an additive for coating, the perfluoropolyether dicarboxylic acid compound or its salt is preferably contained in an amount of 0.01 to 10 parts by mass, more preferably 0.05 to 1 part by mass, per 100 parts by mass of the coating composition. If the amount added is within the above range, the surface tension can be sufficiently reduced, and the desired leveling property can be obtained.

[0084] In addition, for example, when the fluorine-based surfactant of the present invention is used as an additive for a fire extinguishing agent, it is preferable to include 0.01 to 10 parts by mass of a perfluoropolyether dicarboxylic acid compound or its salt, more preferably 0.05 to 1 part by mass, relative to 100 parts by mass of the fire extinguishing agent composition. If the amount added is within the above range, the surface tension can be sufficiently reduced, and the desired fire extinguishing effect can be obtained. In addition, even if not only fresh water but also seawater is used as a solvent (dilution water) for diluting the perfluoropolyether dicarboxylic acid compound or its salt, it is possible to exhibit excellent foaming properties and foam stability, and sufficient fire extinguishing performance. EXAMPLES

[0085] The present invention will be further described below with reference to examples, but the present invention is not limited thereto. ( 1 H-NMR analysis conditions) Equipment: JNM-ECZ400S manufactured by JEOL Ltd. Frequency: 400MHz Deuterated solvent: deuterated methanol Reference peak: tetramethylsilane was set at 0.00 ppm.

[0086] (Materials used) Terminally methyl esterified perfluoropolyether:

[0087] [ka]

[0088] CAE-500, manufactured by Sinochem: (n=0) molecular weight 344.08 CAE-600, manufactured by Sinochem: (n=1) molecular weight 510.10 CAE-1000, manufactured by Sinochem: (n=3) molecular weight 842.15 Diamines: NMAEA: N-methylaminoethylamine NMAPA: N-methylaminopropylamine Haloalkyl carboxylates: Sodium chloroacetate Comparative Example Compound 1: Betaine-type surfactant (synthesized with reference to US 3839425)

[0089] [ka]

[0090] Comparative Example Compound 2: Anionic surfactant synthesized from CAE-600 and L-tyrosine

[0091] [ka]

[0092] CAE-600 (2.82g, 0.00553mol), L-tyrosine (1.00g, 0.00552mol), 1,8-diazabicyclo[5.4.0]undecene-7 (1.64g, 0.0108mol), and methanol (2.82g, 0.0881mol) were added to a 50mL eggplant flask equipped with a stirrer, and the mixture was stirred at 60°C for 2 hours. Hydrochloric acid and metaxylene hexafluoride were added to the reaction solution, and the reaction solution was separated into layers. After separating the lower layer, the upper layer was extracted with metaxylene hexafluoride. The lower layer and the extract were placed in an eggplant flask, and the solvent was removed using a rotary evaporator, and 3.61g (yield: 99.0%) of an amino acid-modified perfluoropolyether compound was recovered.

[0093] Thereafter, the same mole amount of sodium hydroxide as the amino acid modified perfluoropolyether compound was added to form a sodium salt, and water and hexylene glycol were then added to adjust the concentration to 30% by mass (water:hexylene glycol = 1:1, weight ratio) to obtain comparative compound 2.

[0094] (Synthesis Example 1) Preparation of perfluoropolyether dicarboxylate potassium salt 1 (Example compound 1) Perfluoropolyether dicarboxylic acid potassium salt 1 (Example compound 1):

[0095] [ka]

[0096] 1. Synthesis of amide compounds using CAE-500 and NMAPA 5.00 g of CAE-500 (0.0145 mol), 1.35 g (0.0153 mol) of NMAPA, and 2.53 g of IPA were added to a 50 mL recovery flask containing a stirrer, and the mixture was heated and stirred at 60° C. for 3 hours. After cooling, the IPA and unreacted NMAPA were removed using a rotary evaporator, and 5.33 g (0.0133 mol) of the amide compound was recovered.

[0097] 2. Quaternization of amide compounds In a 50mL three-necked flask containing a stirrer, 5.33g (0.0133mol) of the above amide compound, 2.91g (0.0250mol) of sodium chloroacetate, 2.50g of water, and 5.00g of IPA were added and heated and stirred at the reflux temperature of the solvent for 1 hour. While continuing to heat and stir, 4.98g (0.0125mol) of a 10wt% aqueous solution of sodium hydroxide was added dropwise. The mixture was heated and stirred for a total of 6 hours.

[0098] Then, 2.91 g (0.0250 mol) of sodium chloroacetate was added to the reaction solution, and the mixture was heated and stirred at the reflux temperature of the solvent for 1 hour. While continuing to heat and stir, 4.98 g (0.0125 mol) of a 10 wt % aqueous solution of sodium hydroxide was added dropwise. The mixture was heated and stirred for a total of 6 hours.

[0099] Thereafter, potassium carbonate was added to the reaction solution, and the mixture was stirred to separate the reaction solution into layers. The upper layer containing the target product was separated, and the solvent was removed using a rotary evaporator to recover 6.60 g (0.0131 mol, yield: 98.2%) of Example Compound 1.

[0100] The obtained Example Compound 1 1 H-NMR is as follows: 1 H-NMR(CD3OD)δ(ppm):d 1.8-2.1ppm(2H,m), 3.3ppm(3H,s), 3.4-3.6ppm(2H,t), 3.7-3.9ppm(2H,t), 4.1ppm(4H,s)

[0101] (Synthesis Example 2) Preparation of perfluoropolyether dicarboxylate potassium salt 2 (Example compound 2) Perfluoropolyether dicarboxylic acid potassium salt 2 (Example compound 2):

[0102] [ka]

[0103] 1. Synthesis of amide compounds using CAE-600 and NMAEA 5.01 g of CAE-600 (0.00981 mol), 0.775 g of NMAEA (0.0105 mol), and 2.57 g of IPA were added to a 50 mL recovery flask containing a stirrer, and the mixture was heated and stirred at 60° C. for 3 hours. After cooling, the IPA and unreacted NMAEA were distilled off using a rotary evaporator, and 5.21 g (0.00943 mol) of the amide compound was recovered.

[0104] 2. Quaternization of amide compounds In a 50mL three-necked flask containing a stirrer, 5.21g (0.00943mol) of the above amide compound, 2.16g (0.0181mol) of sodium chloroacetate, 2.50g of water, and 5.00g of IPA were added and heated and stirred at the reflux temperature of the solvent for 1 hour. While continuing to heat and stir, 3.62g (0.00905mol) of a 10wt% aqueous solution of sodium hydroxide was added dropwise. The mixture was heated and stirred for a total of 6 hours.

[0105] Then, 2.16 g (0.0181 mol) of sodium chloroacetate was added to the reaction solution, and the mixture was heated and stirred at the reflux temperature of the solvent for 1 hour. While continuing to heat and stir, 3.62 g (0.00905 mol) of a 10 wt % aqueous solution of sodium hydroxide was added dropwise. The mixture was heated and stirred for a total of 6 hours.

[0106] Thereafter, potassium carbonate was added to the reaction solution, and the mixture was stirred to separate the reaction solution into layers. The upper layer containing the target product was separated, and the solvent was removed using a rotary evaporator to recover 6.38 g (0.00903 mol, yield: 95.7%) of Example Compound 2.

[0107] The obtained Example Compound 2 1 H-NMR is as follows: 1 H-NMR(CD3OD)δ(ppm):d 3.1ppm(3H,s), 3.3-3.5ppm(2H,t), 3.6-3.8ppm(2H,t), 4.1ppm(4H,s)

[0108] (Synthesis Example 3) Preparation of perfluoropolyether dicarboxylate potassium salt 3 (Example compound 3) Perfluoropolyether dicarboxylate potassium salt 3 (Example compound 3):

[0109] [ka]

[0110] 1. Synthesis of amide compounds using CAE-600 and NMAPA 150g of CAE-600 (0.297mol), 27.2g (0.309mol) of NMAPA and 75g of IPA were added to a 500mL recovery flask containing a stirrer, and the mixture was heated and stirred at 60℃ for 3 hours. After cooling, the IPA and unreacted NMAPA were removed using a rotary evaporator, and 165g (0.291mol) of the amide compound was recovered.

[0111] 2. Quaternization of amide compounds In a 1L three-necked flask containing a stirrer, 100g (0.177mol) of the above amide compound, 41.1g (0.353mol) of sodium chloroacetate, 50g of water, and 100g of IPA were added and heated and stirred at the reflux temperature of the solvent for 1 hour. While continuing to heat and stir, 70.6g (0.167mol) of a 10wt% aqueous solution of sodium hydroxide was added dropwise. The mixture was heated and stirred for a total of 6 hours.

[0112] After that, 41.1 g (0.353 mol) of sodium chloroacetate was added to the reaction solution, and the mixture was heated and stirred at the reflux temperature of the solvent for 1 hour. While continuing to heat and stir, 70.6 g (0.167 mol) of a 10 wt % aqueous solution of sodium hydroxide was added dropwise. The mixture was heated and stirred for a total of 6 hours.

[0113] Thereafter, potassium carbonate was added to the reaction solution, and the mixture was stirred to separate the reaction solution into layers. The upper layer containing the target product was separated, and the solvent was removed using a rotary evaporator to recover 106 g (0.150 mol, yield: 85.0%) of Example Compound 3.

[0114] The obtained Example Compound 3 1 H-NMR is as follows: 1 H-NMR(CD3OD)δ(ppm):d 1.8-2.1ppm(2H,m), 3.3ppm(3H,s), 3.4-3.6ppm(2H,t), 3.7-3.9ppm(2H,t), 4.1ppm(4H,s)

[0115] (Synthesis Example 4) Preparation of perfluoropolyether dicarboxylate potassium salt 4 (Example compound 4) Perfluoropolyether dicarboxylate potassium salt 4 (Example compound 4):

[0116] [ka]

[0117] 1. Synthesis of amide compounds using CAE-1000 and NMAPA 5.00 g of CAE-1000 (0.00739 mol), 0.684 g (0.00776 mol) of NMAPA, and 2.74 g of IPA were added to a 50 mL recovery flask containing a stirrer, and the mixture was heated and stirred at 60° C. for 3 hours. After cooling, the IPA and unreacted NMAPA were removed using a rotary evaporator, and 4.97 g (0.00678 mol) of the amide compound was recovered.

[0118] 2. Quaternization of amide compounds In a 1L three-necked flask containing a stirrer, 4.97g (0.00678mol) of the above amide compound, 1.59g (0.0136mol) of sodium chloroacetate, 2.50g of water, and 5.03g of IPA were added and heated and stirred at the reflux temperature of the solvent for 1 hour. While continuing to heat and stir, 2.73g (0.00683mol) of a 10wt% aqueous solution of sodium hydroxide was added dropwise. The mixture was heated and stirred for a total of 6 hours.

[0119] After that, 1.59 g (0.0136 mol) of sodium chloroacetate was added to the reaction solution, and the mixture was heated and stirred at the reflux temperature of the solvent for 1 hour. While continuing to heat and stir, 2.73 g (0.00683 mol) of a 10 wt % aqueous solution of sodium hydroxide was added dropwise. The mixture was heated and stirred for a total of 6 hours.

[0120] Thereafter, potassium carbonate was added to the reaction solution, and the mixture was stirred to separate the reaction solution into layers. The upper layer containing the target product was separated, and the solvent was removed using a rotary evaporator to recover 5.09 g (0.00574 mol, yield: 84.6%) of Example Compound 4.

[0121] The obtained Example Compound 4 1H-NMR is as follows: 1 H-NMR(CD3OD)δ(ppm):d 1.8-2.2ppm(2H,m), 3.3ppm(3H,s), 3.4-3.7ppm(2H,t), 3.8-4.0ppm(2H,t), 4.1ppm(4H,s)

[0122] Example 1 Example compound 1 synthesized in Synthesis Example 1 was diluted with ion-exchanged water to prepare a concentration of potassium perfluoropolyether dicarboxylate 1 of 0.05 mass%, 0.1 mass%, or 0.5 mass% in terms of solid content. Then, the surface tension was measured at each concentration. The results are shown in Table 1.

[0123] In addition, Example Compound 1 was diluted with ion-exchanged water or synthetic seawater to a solid content of 0.1% by mass to prepare a test liquid for foaming and foam stability tests. Then, 50 g of the test liquid was added to a 100 mL vial, and the foaming and foam stability were confirmed from the foam volume immediately after shaking for 1 minute and the change in foam volume after standing at 20°C for 120 minutes. The results are shown in Table 1.

[0124] (Surface tension measurement) Equipment: Surface tension meter DY-300 (Kyowa Interface Science Co., Ltd.) Condition: Wilhelmy platinum plate method Liquid temperature: 20℃ Evaluation criteria ◎:20mN / m or less ○: More than 20mN / m and less than 30mN / m △: More than 30mN / m and less than 40mN / m ×: Greater than 40 mN / m

[0125] (Foaming evaluation) The evaluation criteria for foaming ability were set as follows based on the volume of foam immediately after shaking for 1 minute (Figure 3). ◎: The volume of the foam is greater than the volume of the liquid. ○: The foam volume is more than 50% and less than 100% of the liquid volume. △: The foam volume is 50% or less of the liquid volume. ×: No foaming.

[0126] (Foam Stability Evaluation) The evaluation criteria for foam stability were set as follows, based on the foam volume percentage (%) after standing at 20°C for 120 minutes, when the foam volume immediately after shaking for 1 minute was taken as 100% (Figure 4). ◎:80% or more. ○: More than 60% but less than 80%. △: Between 40% and 60%. ×: Less than 40%.

[0127] (Examples 2 to 4, Comparative Examples 1 and 2) The surface tension, foaming property and foam stability were evaluated in the same manner as in Example 1, except that the compounds shown in Table 1 were used. The results are shown in Table 1.

[0128] [Table 1]

[0129] The results of Examples 1 to 4 reveal that the compounds of the present invention have excellent surface tension reducing ability. In particular, the compounds of Examples 2 and 3 (repeating unit n=1 in the perfluoropolyether portion) were found to exhibit excellent surface tension reducing ability compared to the compounds of Examples 1 and 4.

[0130] In addition, from the results of Examples 1 to 4, it was found that the compounds of Examples 1 to 3, in particular, had high foaming properties when diluted with ion-exchanged water and synthetic seawater. The reason for such an effect is unclear, but the following is expected. Foaming properties are affected by the adsorption speed of the surfactant to the air taken into the liquid. The perfluoropolyether chain of the compound used in Example 4 is longer than that of the compounds of Examples 1 to 3, and the molecule is curved via the ether, so it is considered that the adsorption density to the foam film interface is difficult to increase and the adsorption speed is low. As a result, it is considered that the compound of Example 4 has lower foaming properties than the compounds of Examples 1 to 3.

[0131] Furthermore, from the results of Examples 1 to 4, it was found that all of the compounds had high foam stability when diluted with ion-exchanged water and synthetic seawater. In particular, the compounds of Examples 2 and 3 had higher foam stability than the compounds of Examples 1 and 4. The reason for such an effect is unclear, but the following is expected. One of the factors that affect foam stability is the suction of liquid at the plateau border (the part where the bubbles are in contact) (Figure 5). At the plateau border, the pressure difference between the inside of the bubble and the lamella causes the liquid to flow (drain) toward the lamella with low pressure, resulting in a thinner foam film. Here, the pressure difference between the inside of the bubble and the lamella depends on the radius of curvature of the interface and the surface tension of the liquid, as shown in the Laplace formula below. It is presumed that the surface tension of the solution is lower in the compounds of Examples 2 and 3 than in the compounds of Examples 1 and 4, so the pressure difference between the inside of the bubble and the lamella is smaller, which delays drainage, resulting in better foam stability.

[0132]

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Claims

1. A perfluoropolyether dicarboxylic acid compound or a salt thereof represented by the following formula (1): 【Chemistry 1】 (wherein, Rf １ R is a perfluoroalkyl group having 1 to 4 carbon atoms. １ R is a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms. ２ R is a substituted or unsubstituted hydrocarbon group having 1 to 6 carbon atoms. ３ and R ４ are the same or different and are substituted or unsubstituted hydrocarbon groups having 1 to 4 carbon atoms; and n is an integer of 0 to 5.

2. 2. The perfluoropolyether dicarboxylic acid compound or a salt thereof according to claim 1, wherein the molecular weight of the perfluoropolyether dicarboxylic acid compound represented by the formula (1) is in the range of 400 to 1,700.

3. R ３ and R ４ and are the same or different and are linear alkylene groups having 1 to 4 carbon atoms, or a salt thereof.

4. 2. The perfluoropolyether dicarboxylic acid compound or its salt according to claim 1, wherein n is an integer of 0 to 3.

5. A fluorosurfactant comprising the perfluoropolyether dicarboxylic acid compound or its salt according to claim 1.

6. A composition comprising the perfluoropolyether dicarboxylic acid compound or its salt according to claim 1.

7. A paint comprising the perfluoropolyether dicarboxylic acid compound or its salt according to claim 1.

8. A fire extinguishing agent comprising the perfluoropolyether dicarboxylic acid compound or its salt according to claim 1.

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