GB1591292A

GB1591292A - Method of improving fluorinated surfactants

Info

Publication number: GB1591292A
Application number: GB53942/77A
Authority: GB
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1976-12-30
Filing date: 1977-12-28
Publication date: 1981-06-17
Also published as: DE2758013B2; GB1591293A; DE2758013C3; AU517771B2; NL7714204A; CH634873A5; DE2759790C2; BR7708741A; MX148221A; FR2376208B1; FR2376208A1; JPS6254533B2; BE862459A; DE2758013A1; CA1102652A; JPS5385787A; AU3199477A

Abstract

The surface-tension properties of aqueous solutions of fluorinated surfactants are improved by adding to solutions of these surfactants at least one of the components (1) and (2), in which (1) is a fluorinated synergist of the formula (Rf)nTmZ, in which Rf is straight-chain or branched perfluoroalkyl having 1 to 18 carbon atoms, or perfluoroalkyl having 1 to 18 carbon atoms which is substituted by perfluoroalkoxy having 2 to 6 carbon atoms, n is 1 or 2, T is a divalent group of the formula -R3- or -R3SCH2CHR1-, in which R3 is straight-chain or branched alkylene having 6 to 12 carbon atoms, alkylenethioalkylene or alkyleneiminoalkylene having 2 to 12 carbon atoms, in which the nitrogen atom is secondary or tertiary, and R1 is hydrogen or alkyl having 1 to 12 carbon atoms, where T, if n is equal to 2, is substituted by an additional R radical, Z is a neutral or polar group of the formula -CONR2R4, -CN, -CONR2COR4, -SO2NR2R4 , -R3O2CR2 and -CO2R2, in which R2 and R4, independently of each other, denote hydrogen, or alkyl having 1 to 12 carbon atoms which is optionally substituted once or more than once by -OH, -COCH3, -SH or -CONH(CH3), and R3 has the meaning indicated, m is 0, 1 or 2, and, if m is 0, n can only be 1, where the fluorinated synergist possesses a solubility in water of less than 0.01% by weight at 25 DEG C, and (2) is a magnesium salt.R

Description

(54) METHOD OF IMPROVING FLUORINATED SURFACTANTS (71) We, CIBA-GEIGY AG, a Swiss body corporate, of Basle, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- Numerous surfactant applications depend on the attainment of low surface tensions. Whereas conventional hydrocarbon surfactants can attain surface tensions of as low as 23 dynes/cm, fluorinated surfactants are unique in that they can attain surface tensions of 15-20 dynes/cm, and at best of 14.5 dynes/cm. Such extremely low surface tensions are, however, only reached at high concentrations of fluorinated surfactants and only with highly specific structures. Since fluorinated surfactants are exceedingly expensive, it is imperative that the lowest surface tension is attained with the minimum quantity of surfactants.

The problem of attaining the lowest possible surface tension with fluorinated surfactants has been the subject of innumerable patents and publications, which detail specific and idealized structures having such properties.

In all cases the preferred candidate surfactants have distinctive and highly specific structures, which if varied even slightly often drastically alter the attainable surface tensions. A fundamental reason that the attainment of a minimal surface tension at the lowest practicable use level is not easily answered is that the surface tension decreases as the fluorinated tail increases, while the solubility generally decreases so markedly when even one -CF2- group is added that precipitation of the sparingly soluble fluorosurfactant frequently occurs.

It has long been known that the surface tension of hydrocarbon surfactants, which at best is 26-27 dynes/cm, can be depressed to 23 dynes/cm with sparingly soluble alcohols. In fact, the adventitious nature of this effect is so marked that surface tension curves of conventional commercial surfactants frequently have minima unless the surfactant is scrupulously purified.

Bernett and Zisman, J. Phys. Chem., 65, 448 (1961), teach that synergistic mixtures of conventional hydrocarbon surfactants and fluorinated 1, 1-dihydro alcohols can be prepared which attain low surface tensions with smaller concentrations of the fluorinated agent. The resultant solutions are, however, unstable and the fluorinated alcohols are, moreover, volatile and acidic. With the ammonium salt of a perfluorononaoic acid, the fluorinated 1,1,-dihydroalcohols are not sufficiently soluble and eventually form gelatinous precipitates.

In a further effort to prepare better surfactants the prior art suggested preparing magnesium salts of anionic perfluorinated surfactants (Shinoda et al, J.

Phys. Chem., 76, 909 (1972)) and magnesium salts of hydrocarbon anionic surfactants (Reichenberg, Trans. Faraday Soc., 43, 467 (1947)). It has been found, however, that when a magnesium salt is added to an aqueous solution of a fluorinated surfactant, preferably an anionic fluorinated surfactant, a further substantial lowering of the surface tension of the solution results. The aqueous solutions may contain further ingredients such as fluorinated synergists.

The present invention provides a method of improving the surface tension properties of a solution of a cationic, anionic, non-ionic, amphoteric or mixed function fluorinated surfactant which comprises adding.to the said surfactant solution a component (1) which is a fluorinated synergist of the formula (Rf)nTmZ wherein R, is a straight or branched chain perfluoroalkyl of I to 18 carbon atoms or said perfluoroalkyl substituted by perfluoroalkoxy of 2 to 6 carbon atoms, nis I or2, T is a divalent group -R3- or a group -R3SCH2CHR1- where R3 is straight or branched chain alkylene or haloalkylene of 1 to 12 carbons, arylene of 6 to 12 carbons, alkylenethioalkylene or alkyleneiminoalkylene of 2 to 12 carbons where in said imino group the nitrogen atom is secondary or tertiary and R, is hydrogen or alkyl of I to 12 carbons, Z is a neutral or a polar group which is -CONR1R2, -CN, -CONR, COR2 -SO2NR1R2, -R3(O2CR1) or -CO2R where R, and R2 are independently hydrogen, alkyl of 1 to 12 carbons or alkyl substituted with one or more -OH, -COCH2, -SH or -CONH(CH3), and R3 is as defined above, m is 0, 1 or 2, the fluorinated synergist having a solubility in water at 250C below 0.01% by weight, and, optionally, component (2) which is a magnesium salt.

In one preferred embodiment of the present invention the fluorinated synergist only is added to the solution of the fluorinated surfactant. It is, however, also possible to add to said solution, in particular one containing an anionic fluorinated surfactant, a magnesium salt together with the fluorinated synergist.

The surface tension of cationic, anionic, non-ionic amphoteric or mixed function fluorinated surfactants is improved by the use of a fluorinated synergist regardless of the specific structure of the surfactant. For the purpose of illustration the fluorinated surfactants can be represented by the general formula (Rt)nAmQ wherein Rf, n and m are as defined above and Q is a water solubilizing group which is an anionic, cationic, non-ionic or amphoteric moiety, or a combination of such moieties, A is a multivalent linking group, preferably a divalent group such as alkylene of 1 to 12, and preferably of 1 to 4, carbon atoms; arylene, alkyl substituted phenylene or the group C0H4YC6H4 where Y is alkylene of 1 to 4 and preferably methylene, oxygen or sulfur, sulfonamidoalkylene or carbonamidoalkylene.

Typical anionic groups of Q are carboxylic, ammonium or metal carboxylate where the metal is an alkali or alkali earth metal, especially sodium, potassium, calcium or magnesium, sulfinic or sulfonic acid group or ammonium or a metal salt thereof or phosphonic (OP(OH)2) or phosphoric (OP(OH)3) acid group or ammonium or metal salt thereof. Typical cationic groups of Q are -NH2, -NHR where R is lower alkyl (of I to 4 carbons), -NR'X where R3 is hydrogen or lower alkyl and X is an anion such as a halide, especially chloride, sulfate, phosphate or hydroxyl. Typical non-ionic groups of Q are amine oxides and groups derived from polyethylene oxide and mixed polyethylene oxide- polypropylene oxide polyols.

Typical amphoteric and mixed groups are respectively -N(CH3)2C2H4CO2 and -N(CH3)(C2H4CO2H) 0.

The mixed group surfactants are those fluorinated surfactants which within the same molecule contain anionic and cationic moieties or anionic and non-ionic moieties or cationic and non-ionic moieties or cationic and amphoteric moieties or anionic and amphoteric moieties or non-ionic and amphoteric moieties. The above mentioned classes of fluorinated surfactants are also exemplified in German Offenlegungsschrift No. 2 656 677.

A is a multivalent linking group, preferably a divalent group such as alkylene of I to 12 and preferably of 1 to 4 carbon atoms; arylene such as phenylene, alkyl e.g. of I to 4 carbon atoms substituted phenylene or the group CeH4YCeH4 where Y is alkylene of I to 4 and preferably methylene, oxygen or sulfur; sulfonamide alkylene and carbonamidoalkylene.

The R, group can be, as stated above, broadly a perfluoroalkyl of 1 to 18 carbons, but preferably it is perfluoroaliphatic of 5 to 12 carbon atoms.

It should be noted that in some instances more than one Rf group may be bonded through multivalent linking groups A to a single Q group and in other instances, a single R, group may be linked through a multivalent linking group A to more than one polar solubilizing group Q.

The synergist component terminates in a covalently bonded group TmZ which is not critical as such. However, the overall solubility property as determined by the interrelationship of the moieties Rf, T and Z is important in establishing the effectiveness of the synergist. It is generally necessary that the combination of the fluorinated radical and the terminating group be so balanced that the solubility of said synergist in water at 250C is minimal, generally below 0.01% by weight. In the case of R,-surfactant/R,-synergist compositions, the solubility of the composition should be at least 0.1% by weight and in order to function affectively as a useful composition should provide a surface tension below 28 dynes/cm, preferably below 23 dynes/cm in aqueous/solvent solution.

The fluorinated synergistic compound generally has a very limited solubility in water, but an enhanced solubility in the presence of the fluorinated surfactant. The critical aspect of the invention is that diverse fluorinated surfactants can be used for purposes of the invention, which surfactants do not have idealized surface active properties. The synergistic additive effectively permits the resultant compositions to have markedly superior surface properties.

Consequently, the major component of these compositions may be a fluorinated surfactant which is chosen not on the basis of unique surface properties but on the basis of its economic feasibility of synthetic availability. In fact, it may contain a mixture of fluorinated telomer derived end groups from C4F9- to C14F29-, be derived from fluorinated surfactants with highly branched tails, which do not generally exhibit good surface properties, or may contain some degree of hydrogen or chlorine substitution.

Because the synergistic additive is neutral, it is compatible with anionic, cationic, non-ionic or amphoteric structures, all of which give compositions with improved properties. This permits the choice of a fluorochemical surfactant type for an application independent of its surface properties and more nearly based on its price and availability.

The fluorochemical synergists are generally inexpensive and are readily attainable fluorochemical derivatives. They too may contain a mixture of fluorinated telomer derived end groups from C4F9- to C14F29-, but preferably the lower, more soluble homologs. While the syner ists can have diverse functionalities, the most effective synergists are neutral yet contain highly polar functions and most preferably polar functions that can be solubilized by hydrogen bonding. Strongly acidic or basic, corrosive or volatile, or otherwise unstable fluorochemical derivatives are not recommended as synergists for purposes of this invention.

This invention is also directed to a method of lowering surface tension of an aqueous solution of an alkali metal salt of an anionic fluorinated surfactant by adding thereto together with the synergist from 0.1 to 5 equivalents per equivalent of said anionic surfactant of a magnesium salt which is magnesium sulfate, magnesium nitrate, magnesium chloride or magnesium acetate.

Although all above listed magnesium salts are very effective in lowering the surface tension, magnesium sulfate is preferred from an economic and corrosion standpoint. Also from the economic (cost/performance) standpoint it is preferable that the magnesium salt is used in the amount of 1 to 4 equivalents per equivalent of the anionic surfactant, and most preferably in the amount of 1.5 to 2.5 equivalents.

Furthermore, the magnesium salt lowers the surface tension most effectively if the surfactant solution is made using distilled or deionized water to low hardness water, that is, water containing less than 5 mg/l of minerals, in other words, having less than 5 ppm (parts per million) of minerals.

The method of this invention is effective especially with fluorinated anionic surfactants, regardless of the chemical structure. Preferred anionic fluorinated surfactants are carboxylic acids and salts thereof, sulfonic acids and salts thereof, phosphonates, phosphates, related phosphoro derivatives and salts thereof.

The present invention also provides an aqueous surfactant composition having improved surface properties which contains a mixture of a cationic, anionic, nonionic, amphoteric or mixed function fluorinated surfactant and component (1) a fluorinated synergist of the formula (Rf)nTmZ wherein R, is a straight or branched chain perfluoroalkyl of I to 18 carbon atoms or said perfluoroalkyl substituted by perfluoroalkoxy of 2 to 6 carbon atoms, n is 1 to 2, T is a divalent group -R3- or a group -R3SCH2CHR1- where R3 is straight or branched chain alkylene or haloalkylene of I to 12 carbons, arylene of 6 to 12 carbons, alkylenethioalkylene or alkyleneiminoalkylene of 2 to 12 carbons where in said imino group the nitrogen atom is secondary or tertiary and R, is hydrogen or alkyl of 1 to 12 carbons, Z is a neutral or a polar group which is -CONR1R2, -CN, -CONR1COR -SOJR1R , -R3(O2CR1) or -CO2R where R1 and R2 are independently hydrogen, alkyl of 1 to 12 carbons or alkyl substituted with one or more -OH, -COCH3, --SH or -CONH(CH3), and R3 is as defined above, m is 0, 1 or 2, the fluorinated synergist has solubility in water at 250C below 0.01% by weight, and, optionally, component (2) a magnesium salt.

Of special interest are those compositions which contain a mixture of said fluorinated surfactants and the fluorinated synergists, or a mixture of an anionic fluorinated surfactant, a fluorinated synergist and a magnesium salt.

Further preferred are those compositions which contain an alkali metal salt of the anionic fluorinated surfactant and 0.1 to 5 equivalents per equivalent of the surfactant of a magnesium salt which is magnesium sulfate, magnesium nitrate, magnesium chloride or magnesium acetate together with the synergist. In these compositions magnesium sulfate is the most suitable species.

The resultant fluorinated synergist/fluorinated surfactant and synergist/fluorinated surfactant/magnesium salt compositions of this invention can be used advantageously in place of conventional fluorinated surfactants for all purposes for which conventional fluorinated surfactants are recommended.

Naturally, various synergist/surfactant mixtures will be preferable for special considerations. For example, while cationic or anionic surfactant derived compositions may exhibit special substantivity, amphoteric or non-ionic fluorosurfactants may be more preferable for compatibility with the overall formulation.

Thermal or hydrolytic stability considerations may lead to the choice of particularly stable functionalities for both synergist and surfactant, e.g. acid plating baths; non-ionic surfactant derived compositions may have special utility in nonaqueous or low foaming formulations; cationic surfactant derived compositions may be particularly synergistic with disinfectants. These examples are merely exemplary of the synergistic compositions, and preferred compositions should be chosen with due regard to the actual application. These compositions, just as conventional fluorochemical surfaciants, are useful for improving or imparting properties such as wetting, penetration, spreading, levelling, foam stability, flow properties, emulsification, dispersion, and oil and water repellency. Based on these unique properties are numerous applications, some of which follow. Although applications are suggested for a particular use area, the general applicability of each concept is to be inferred for other applications.

Plastics and Rubber Industry Emulsifying agent for polymerization, particularly fluoromonomers As a latex stabilizer To aid in the preparation of agglomerates of powdered fluorocarbon polymers In synergistic mixtures with hydrocarbon surfactants to wet low energy surfaces including natural and synthetic rubbers, resins, plastics As an adjuvant for foam applications and as foaming agents to aid in leak detection As a foam additive to control spreading, crawling, edge buildup As a mold release agent for silicones In refractory processes As an antimist film former Additive for elimination of trapped air in plastic laminates Wetting agent for resin molds fdr definition, strength Hot-melt additive for oil and grease repellency Resin additive for improved wetting of and bonding with fillers Flow modifier for extruding hot melts: spreading, uniformity, anticratering Adjuvant for resin etchant Mold release agent, demolding agent Retarder for plasticizer migration or evaporation Internal antistatic agent for polyolefins Antiblocking agent for polyolefins Petroleum Industry Wetting assistant for oil well treatments, drilling muds As a film evaporation inhibitor for gasoline, jet fuel, solvents, hydrocarbons Lubricating, cutting oil improver, to improve penetration times In extreme pressure lubricants Oil spill collecting agent Additive to improve tertiary oil well recovery Textile and Leather Industries Soil release and soil proofing agent Oil/water repellent textile and leather treatment Wetting agent to improve coverage and penetration of pores of substrates Antifoaming agent in textile treatment baths Wetting agent for finish-on-yarn uniformity Penetrating agent for finishes on tow, heavy denier fibers Emulsifying agent/lubricant for fiber finishes Cleaner/metal treating agent for polymerization equipment Flow modifier for spinning of hot melts, solutions Additive for fabric finishes for spreading, uniformity Wetting agent for dyeing Penetration aid for bleaches Wetting agent for binder in nonwoven fabrics Paint, Pigment and Finishing Industries Levelling, anticratering adjuvant for finishes and paints Adjuvant for control of soiling Agent to control differential evaporation of solvents Leveling agent for floor waxes Adjuvant for waxes to improve oil and water repellency Adhesion improver for oily or greasy surfaces To combat pigment flotation problems Improver for automotive finishes, based on water-based coatings in which the pigments are rendered nonreactive Pigment grinding aid to promote wetting, dispersion, color development Foam generator substance for the application of dyes, inks Electrolytic conversion coatings Mining and Metal Working Industries In cleaning agents for property improvement Additive for solvent cleaning Additive for metal pickling baths to increase bath life and acid runoff Additive for chrome electroplating: surface tension reduction, foaming Additive for soldering flux, especially for electronic circuitry Protective agent for coatings (tarnish resistance, grease repellency) Corrosion inhibitor Additive for etchant solution for improved definition To form antimist films and anticondensation surfaces Plastic preplate and silicon etchant technology In soldering flux for microelectronics to reduce foaming In chemical roughing agent solutions, prior to galvanization As a colloidal dispersion aid for magnetic solids Protective coatings for aluminum and as an antiblocking agent Wetting agent for leaching copper ores and as a froth flotation agent To promote ore wetting and quicker breaking of the protective oxide layer Pharmaceutical Industry Improve the properties and penetration of antimicrobial agents Improve the properties of biochemicals, biocides, algicides, bacteriocides and bacteriostats Improve the strength, homogeneity, and reduce the permeability of encap sulated materials Emulsify fluorochemical blood substitutes Agriculture and Forestry Wetting agent for herbicides, fungicides, weed killers, hormone growth regulators, parasiticides, insecticides, germicides, bactericides, nematocides, microbiocides, defolients and fertilizers As an ingredient in chemosterilents, insect repellents and toxicants For wettable powder pesticides and chemical powders Corrosion inhibitor for chemical applicators Wetting agent for foliage Wetting additive for live stock dips, or to wet sheep skins during desalina tion Wetting adjuvant for manufacture of plywood veneer Penetrant for preservative impregnation Pulping aid For cleaning tubes in paper making, dyeing Grease/oil repellents for paper Fire Fighting Wetting agent for fighting forest fires Ingredient for AFFF, aqueous film forming extinguishing agents (foams) Component of fluoroprotein foams Additives to dry chemical extinguishing agents Agent in aerosol-type extinguishers Wetting agent for sprinkler water Automotive, Building Maintenance and Cleaning Wetting agent for cleaning compositions Additive for alkaline cleaners Glass cleaner Wetting agent for automobile waxes Adjuvant to improve oil/water repellency of wax Lubricant/corrosion inhibitor for antifreeze Rinse-aid for car washes In dry cleaning compositions and solvent cleaners, for water displacement and foaming. May improve soil suspension and decrease redeposition Foaming agents for pipe cleaning Anti-mist film foamer for glass and plastics In foams for dust suppresion Cleaner for building exteriors For acidic concrete cleaners Air entrainment additive for low density concrete Bubble foamer for air tracing, in ventilating systems Household, Cosmetic and Personal Products Rinse-aid for dishwashing Liquid polishing compositions Floor polish levelling agent Additive for alkaline oven cleaners Synergistic improver for disinfectants Carpet cleaners Synergistic wetting agent in detergent formulations Additive for protective coatings on metals (tarnish resistance, grease resistance) Gloss and antistatic improver Hair shampoo ingredient Shaving foam ingredient Oil and water repellent cosmetic powders ingredient Ingredient of lotions or creams for skin or hair Ingredient of skin protection creams Photography and Graphic Arts Printing ink additive for ink flow and levelling, both aqueous and solvent based Wetting agent for writing inks To combat pigment flooding and flotation in printing inks To form ink repellent surfaces for waterless lithoplates, or electrographic coatings Prevent reticulation of gelatin layers and improve uniformity Assist in film drying Improve film coatings and reduce "contraction flecks" Wetting, levelling, anti-cratering assist agent Surfactant for developer solutions Photoemulsion stabilizer Prevent photo-lubricant agglomeration Coating aid in the preparation of m-ultiple layer film elements Antistatic wetting agent for film coatings Antifogging agent for films Bonding agent for fillers and fluoropolymer films In coatings for nematic liquid crystal cells Illustrative examples of Rf-anionics which can be used in the compositions of this invention are the below shown acids and their alkali metal salts. Preferred anionic groups are carboxylate and sulfonate. The anionic surfactant should generally contain 3045% of carbon bound fluorine in order to attain suitable solubility properties. The anionic surfactant may be present as free acid, an alkali metal salt thereof, ammonium, or substituted ammonium. The following patent numbers appearing in parenthesis are patents which more fully disclose the represented class of compounds.

Carboxylic Acids and Salts thereof RfCOOH (Scholberg et al, J. Phys. Chem. 57, 923-5 (1953) Rf(CH2)1-20COOH (German 1,916,669) RfO(CF2)2-20COOH (German 2,132,164) RfO(CF2)2~20(CH2)2~20COOH (German 2,132,164) RfO(CH2),~20COOH (U.S. 3,409,647) R,SO2N(C2N5)CH2COOH (U.S. 3,258,423) RfO(CF2O)3CF2COOH (French 1,531,902)

(French 1,537,922) RfO[CF(CF(CF3)CF2O]CF(CF3)CON(CH3)CH2COOH (U.S. 3,798,265) (C2F5)2(CF3)CCH2COOH (British 1,176,493) C10F19OC6H4CON(CH3)CH2COOH (British 1,270,662) Rf(CH2)1-3SCH(COOH)CH2COOH (U.S. 3,706,787) Rf(CH2)1-12S(CH2)1-17COOH (German 2,239,709; U.S. 3,172,910) Sulfonic Acids and Salts Thereof RfSO3H (U.S. 3,475,333) RfC6H4SO3H (German 2,134,973) Rf(CH2)1-20SO3H (German 2,309,365) RfSO2NHCH2C6H4SO3H (German 2,315,326) RtSO2N(CH3)(C2H4O)1 20SO3H (South African 693,583) RfCH2CH2OCH2CH2CH2SO3H (Canadian 842,252) RtOC8H4SO3H (German 2,230,366) C12F23OC6H4SO3H (German 2,240,263) (C2F5)3CO(CH2)3SO2H (British 1,153,854) CF3(C2Fs)2CO(CH2)3SO3H (British 1,153,854) (C2F5)2(CF3)CCH = C(CF3)SO3H (British 1,206,596) RfOCF(CF3)CF2OCF(CF3)CONHCH2SO3H (U.S. 3,798,265) Rf(CH2)1 or O2-(C2H4O)1-12-SO3H (German 2,310,426) Phosphonates, Phosphates, Related Phosphoro Derivatives, and Salts Thereof RfPO(OH)2 (Rf)2PO(OH) (German 2,110,767) RfSO2N(Et)C2H4OPO(OH)2 (German 2,125,836) RfCH2OPO(OH)2 (German 2,158,661) C8F16OC8H4CH2PO(OH)2 (German 2,215,387) RfOC ,H4CH2PO(OH)2 (German 2,230,366) Others (and Salts Thereof) RfSO2N(CH3)C2H4OSO3H (German 1,621,107) R,C6H4OH (U.S. 3,475,333) Rf(CH2)1-20S2O3Na (German 2,115,139) Rf(CH2)1-20SO2N(CH3)CH2CH2S2O3Na (German 2,115,139) Rf....SO2H (U.S. 3,562,156) Illustrative examples of Rrcationics and Rf-amphoterics which can be used in the compositions of this invention are described in Table lc and Ib, but also include compounds more fully disclosed in the following patents.

United States 2,727,923, 2,759,019, 2,764,602, 2,764,603, 3,147,065, 3,207,730, 3,257,407, 3,510,494, 3,630,951, 3,681,413, 3,681,441, 3,759,981, 3,766,274, 3,828,085, 3,839,425, 3,933,819, 3,941,705, 3,957,657 German 1,925,555, 2,013,104, 2,119,302, 2,120,868, 2,127,232, 2,132,164, 2,165,057, 2,215,387, 2,219,642, 2,224,653, 2,230,366, 2,236,729, 2,239,709, 2,315,326, 2,325,855, 2,337,638, 2,357,916, 2,438,868, 2,523,402 British 1,270,662, 1,288,678, 1,289,436 French 2,035,589, 2,128,028 Belgium 788,335, 801,585 Illustrative examples of Rrnonionics which can be used in the compositions of this invention are described in Table Id, but also include compounds more fully disclosed in the following patents.

United States 2,723,999, 3,621,059, 3,721,700, 3,883,596, 3,952,075, 1,925,555, 1,966,708, 2,160,852, 2,215,386 German 2,215,388, 2,230,366, 2,244,028, 2,250,718, 2,325,855, 2,334,346, 2,337,638, 2,501,239 British 1,130,822, 1,148,486, 1,155,607, 1,176,492 Belgium Netherlands Japanese (early publication) 817,369 7,009,980 75-157,275 Illustrative examples of Rf-synergists which can be used in the compositions of this invention are given in Table 2 and also include: C8F17SO2NH2 C8F17SO2N(C2H5)CH2CHOHCH2OH C8F17SO2N(CH3)CH2CHOHCH2OH C6F17SO2N(CH2CH2OH)2 C8F17SO2N(CH2CH2SH)2 C6F13CH2CH2SCH2CH2CONHCH2OH C8F17SO2N(CH2)C10H20CH2OH C7F15CON(C2H5)CH2CH2OH CF3C8F10SO2N(C2H5)CH2CH2OH C3F7O(C3F6O)2CF2CON(CH3)C3H6OH C8F17SO2N(C4H9)CH2CHOHCH2OH

C8F17SO2N[CH2CH2CON(CH3)H]2 Also (C2F5)2(CF3)C-CH3CON(R)CH2CH2OH wherein R is H, Ch3, C2H5 or CH2CH2OH disclosed in British Specification No. 1,395,751; Rf(Ch2CFR1)mCH2CH2CN wherein F1 = H or F, m = 1-3 as disclosed in British Specification No. 1,429,279; and compounds of the general structure: Rf~CH2CH2-SOxCmH2mA as described in Ferman DOS 2,344,889 wherein x is 1 or 2, Rf is as described above, m is 1 to 3 and A is carboxylic ester, carboxamide or nitrile.

The following Examples further illustrate the present invention.

Experimental Part Tables la through Id list Rranionic, amphoteric, cationic, and nonionic surfactants and Table 2 lists Resynergists which are used in the examples following the tables.

The commercially available surfactants used in the examples are: F-1, which is an alkali metal salt of a perfluoroalkylsulfonic acid F-2, which is a perfluoroalkanesulfonamido alkylenemonocarboxylic acid salt as disclosed in U.S. 2,809,990 F-3, which is a cationic quaternary ammonium salt derived from a perfluoro alkanesulfonamidoalkylenedialkylamine as disclosed in U.S. 2,759,019, namely, C8F17SO2NHC3H6N(CH3)3I F-4, which is a nonionic perfloroalkanesulfonamido polyaklylene oxide derivative F-5 and F-6, anionics derived from linear perfluoroalkyl telomers F-7, an amphoteric carboxylate derived from linear perfluoroalkyl telomers F-8, a cationic quaternary ammonium salt derived from linear perfluoroalkyl telomers F-9, a nonionic derived from linear perflor TABLE la Fluorinated Anionic Surfactants used in Examples 1 to 95

Rf Surfactant Name Formula A1 2-Methyl-2-(3-[1,1,2,2-tetra- RfCH2CH2SCH2CH2CONHC(CH3)2CH2SO3Na hydroperfluoroalkylthio pro- wherein: %C6F13 %C8F17 %C10F21 pionamide)-1-propanesulfonic acid, sodium salt 39 41 13 A2 as above 44 42 10 A3 as above 52 35 8 A4 as above 60 36 4 A5 as above 32 42 21 A6 as above 27 44 23 A7 as above 20 48 26 A8 as above, 45% 100 A9 as above, 45% 100 A10 as above, 100% 100 A11 | 1,1,2,2-Tetrahydroperfluoro- | RfCH2CH2SO3K alkylsulfonate, potassium wherein: 20 40 20 salt A122 Perfluoroalkanoic acid, potassium salt RfCOOK 32 62 6 A13 A8, magnesium salt %C6F13 100 A14 | F-1 A15 F-2 A16 F-S A17 F-6 A18 F-9 A19 F-10 A20 C8F17SO2N(C2H,)CH2CO2K A21 | | C8F17SO3K A22 C8Fl7SO2NHCH2 C6H4SO3Na Rf is a mixture consisting principally of C6 F13, C8F,7, and CloF2l in the approximate ratio 2:2:1 or as stated. 35% solution in 17.5% hexylene glycol - 47.5% water or as otherwise stated.

2 Approximate homolog distribution.

TABLE ib Fluorinated Amphoteric Surfactants used in Examples 1 to 95

Rf Surfactant Name or Formula Formula A23a N-[3-(dimethylamino)propyl]-2 and 3- %C6F13 %C8F17 %C10F21 (1,1,2,2-tetrahydroperfluoroalkylthio) succinamic acid, 60% solids 32 36 22 A23b ditto 39 41 13 A23c ditto 44 42 10 - + A24 C6F13SO2N(CH2CO2)C3H6N(CH3)3 0+ 0 A25 | C6F13CH2CH2SCH2CH2N(CH3)2CH2CO2 O 9 A26 C8F17C2H4CONH(CH2)3N(CH3)2CH2CH2CO2 - + A27 C F SO N(C H SO )C H N(CH ) (C H OH) A27 C6 F13SO2N(C3H6SO3) C6H6N(CH2)2 (C2H4OH) - + A28 C8F17CH2CH(CO2)N(CH3)3 - + A29 C, F3SO2N(CH2 CH2 CO2)C3H6N(CH3)2CH2 CH2OH A30 F-14 (Du Pont) + A31 C7F15CONHC3H6N(CH3)2CH2CH2CO2 TABLE ic Fluorinated Cationic Surfactants used in Examples 1 to 95 Rf-Surfactant Name or Formula + A32 C8F17SO2NHC3H6N(CH3)3Cl + A33 C8F17SO2NHC3H6N(CH3)2C2H5OSO2OC2H5 + A34 C8F17SO2NHC3H6N(CH3)3I + A35 C7Fls CONHC3H6N(CH3)3CI + A36 C8F17SO2NHC3H6N(CH3)2CH2C6H5Cl + A37 C8F17SO2N(CH3)C3H6N(CH3)3I

+ A39 C6F13CH2CH2SCH2CH2N(CH3)3I A40 F-3 A41 F-8 A42 F-i 5 (J CJ) TABLE id Fluorinated Non-ionic Surfactants used in Examples Rf-Surfactant Name or Formula A43 F-4 A44 F-9 A45 F-13 TABLE 2 Rf-Synergists used in Examples

Rf Synergist Name Formula RfCH2CH2SCH2CH2CONH2 wherein: B1 3-[1,1,2,2-tetrahydroperfluoroal- %C6F13 %C8F17 %C10F21 kylthio]propionamide 65 23 5 B2 as above 67 10 1 B3 as above 80 1.4 1 B4 as above 71 23 2 BS as above 35 36 20 B6 as above 100 B7 as above 100 RfCH2CH2SCH2CH2CN B8 3-[1,1,2,2-tetrahydroperfluoroal- wherein: kylthio]propionitrile 40 42 12 B9 as above 100 B10 as above 100 RfCH2CH2SCH2CH(CH3)CONH2 B11 2-methyl-3-[1,1,2,2-tetrahydroper- wherein: fluoroalkylthio]propionamide 40 42 12 B12 as above 100 B13 N-[2-(2-methyl-4-oxopentyl)]3- RfCH2CH2SCH2CH2CONHC(CH3)2CH2COCH3 [1,1,2,2-tetrahydroperfluoroal- wherein: kylthio propionamideJ 40 42 12 B14 as above | 100 B15 N-methylol-3-[1,1,2,2-tetrahydro perfluoroalkylthio]propionamide 100 B16 perfluorooctanamide 100 (C7F15CONH2) RfCH2CH2SCH2CH2CONHC(CH3)2CH2COCH3 wherein: B17 perfluorooctanonitrile %C6F13 %C8F17 %C10F21 100 (C7F15CN) B18 N-methyl-perfluorooctane (C,F17SO2NHCH2) sulfonamide 100 B19 N-methyl, N-hydroxyethyl (C8F17SO2N(CH3)CH2CH2OH) perfluorooctane sulfonamide 100 B20 1,1,2,2-tetrahydroperfluoroalkyl- 100 (RfCH2CH2SCH2CH2OCOCH3) thioethylacetate B21 2-iodo,1,1,2,3 ,3-pentahydroper- C6F13CH2CIIICH2CN fluorononyl nitrate Examples 1 to 16.

Fluorinated surfactants of the diverse types shown in Table 3 were compared at the same dilution in the presence of a-typical R,-synergist B6, with and without added megnesium sulfate. As is shown without exception, the observed surface tension is markedly reduced in the presence of Rf-synergist.

When the Rf-synergist is used on the various surfactants in conjunction with magnesium sulfate not only are all the observed surface tensions markedly reduced, but the effect on Rranionic surfactants is especially pronounced.

The test solutions exhibit varying degrees of clarity and, significantly, many of the solutions are clear. It has been found that the addition of small quantities of conventional hydrocarbon surfactants to the cloudy compositions will frequently improve their compatibility.

TABLE 3 Effect of Rf-Synergists on Rf-Surfactants Rf-Surfactant ..................... Variable .......................... 1.67%4 Rf-ynergist ......................... B6 .......................... 0.33% Solvent ........................................................... 25% Magnesium Sulfate Heptahydrate ...................................... 0.6 %

Example Surface Number Rf-Surfactant Rf-Synergist MgSO4.7 H2O Tension Clarity, none + - 35 c 5 1 F-1 - - 26.0 " anionic + - 18.4 a " + + 15.7 a 2 F-2 - - 20.4 b " anionic + - 18.8 c " + + 17.1 c 3 F-3 - - 18.5 " cationic + - 15.8 " + + 15.8 4 F-9 - - 26.0 " anionic + - 22.8 b " + + 20.0 5 F-13 - - 22.7 c " non-ionic + - 21.1 c " + + 21.8 c 6 F-15 - - 28.5 " cationic + - 24.2 " + + 22.9 7 F-5 - - 18.3 " anionic + - 17.1 a " + + 16.9 b 8 F-6 - - 19.3 " anionic + - 17.9 b " + + 17.9 c 6% dilution in distilled water; corresponds to 0.1% Rf-surfactant and 0.02% Rf-synergist Inredient present (+), absent (-) Clarity: - = clear; a = opalescent; b = slight precipitate; c = precipitate 4 Ingredients corrected for dilution as necessary; 100% actives 5 Filtered solution for measurement of surface tension.

TABLE 3 (Continuation) Example Surface Number Rf-Surfactant Rf-Synergist MgSO4.7 H202 Tension1 Clarity 9 F-7 - 17.8 - amphoteric + - 16.3 + + 16.3 - 10 F-9 - - 20.8 " non-ionic + - 18.1 b 3 + + 18.0 a 11 F-8 - - 19.9 " cationic + - 15.6 b " + + 15.8 12 A23b - - 19.7 amphoteric + - 16.7 + + 16.1 13 A12 - - 24.9 anionic + - 21.6 c + + 16.1 c 14] Al - - 2839 - anionic + - 21.4 b + + + 17.1 15 A8 - - 29.6 anionic + - 23.4 b + + 15.6 16 A13 - - 19.6 anionic + - 15.8 6% dilution in distilled water; corresponds to 0.1% Rf- surfactant and 0.02% Rf-synergist Ingredient present (+), absent (-) Clarity: - = clear; a = opalescent; b = slight precipitate; c = precipitate Examples 17 to 24.

Table 4 shows that Rf-synergists of widely diverse types will all effectively depress the surface tension of a typical R,-surfactant from its initial surface tension of 28.9 dynes/cm (see Table 3).

Surface tensions of 15-17 dynes/cm are generally attainable, a remarkable depression of 11-13 dynes/cm. Even in the absence of magnesium salt, substantial synergist effects are observed. With rare exception, surface tension values as low as 15-16 dynes/cm at such low fluorinated surfactant concentration have not previously been reported. In fact, these low synergistic surface tensions approach 14.5-15.0 dynes/cm, which is believed to be the lowest theoretically attainable value for an aqueous fluorosurfactant.

TABLE 4 Effect of Rf-Synergist Types Anionic Rf-Surfactant ............................. A1 .............. 1.67% Rf-Synergist ..................................... Variable ......... Solvent ......................................... E4 .............. 25% Magnesium Sulfate Heptahydrate ..................................... 0.5%

Example Surface Number Rf-Synergist Concentrate % MgSO4.7H2O Tension Clarity4 17 B6 0.33 - 21.4 b + 17.1 b 18 B9 0.33 - 18.8 b + 17.5 1.10 - 18.3 + 15.0 19 B12 0.33 - 21.1 + 17.6 b 1.10 - 23.3 b + | 15.8 | 20 B14 0.33 - 21.9 b + 18.3 b 1.10 - 19.4 b + 16.8 21 B18 0.33 f 20.1 6 + 16.6 22 B19 0.33 f 19.4 - + 18.8 23 B17 0.33 + 18.2 b 24 B21 0.33 - 18.5 + 16.2 1 Ingredients corrected for dilution as necessary; 100% actives 2 Ingredient present (+), absent (-) 6% dilution in distilled water corresponds to 0.10% Rf-surfactant, and 0.02% Rf-synergist for 0.33% Rf-synergist; 0.067% Rf-synergist for 1.1% Rf-synergist 4 Clarity: clear; b - slight precipitate Examples 25 to 30.

Table 5 shows how in Examples 26 and 27 versus 25 and Examples 29 and 30 versus 28, compositions with Rrsynergist exhibit much lower surface tensions than do the R,-surfactants alone, and certain Rf-surfactant/Rf-synergist mixtures are better than others. The marked improvement in properties Is apparent even at 0.01% concentration and a divalent salt is not present.

TABLE 5 Surface Tension Versus Concentration

Surface Tension (dynes/cm) Example Solids Composition % Solids Number Rf-Surfactant Parts Rf-Synergist Parts 1.0 .1 .01 .001 .0001 25 A1 100 - - - 27 30 42 57 26 Al 75 B1 25 - 16.7 19.8 33.8 51.5 27 A2 82 B2 18 - 16.3 22.1 32.9 54.3 28 A23a 100 - - 20 20 21 28 61 29 A23b 72 B1 25 - 15.1 15.6 27.3 54.2 30 A23c 82 B2 18 - 16.0 16.7 34.0 60.5 The compositions contain 45% solids in 20/80 hexylene glycol/water.

Examples 31 to 38.

Table 6 shows how the CMC plots of the subject compositions are affected by the addition of a preferred R,-synergist. The surface tensions are progressively improved over the entire concentration range as R,-synergist B6 is added, both with and without magnesium ions present. Values with magnesium are considerably better and the solutions are apparently more stable. Approximately 10% of the synergist is sufficient to attain a minimum surface tension.

TABLE 6 Surface Tension Versus Concentration

Surface Tension Solids Composition (dynes/cm) Example Rf-Surfactant Rf-Synergist MgSO4.7H2O % Solids 2,3 Number A3 parts B6 parts parts .1 .01 .001 31 100 - - 28.2 26.6 48.1 32 100 6.6 - 21.7 20.2 41.7 33 100 13.2 - 18.9b 21.4 42.1 34 100 20.0 - 19.0b 20.6 40.0 35 100 - 30 19.7 20.1 43.9 36 100 6.6 30 17.3 16.5 34.7 37 100 13.2 30 16.4 15.7 30.8 38 100 20.0 30 15.8 15.8 30.0 The compositions contain approximately 2% solids in 25/75 butyl carbitol/water 2 Based on Rf-Surfactant A3 3 Clarity: clear unless denoted b, slight precipitate within 1 day.

Examples 39 to 66.

Table 7 shows Examples 39 to 66 can be prepared as compositions which exhibit improved surface properties.

TABLE 7 Other Effective Fluorinated Synergist/Surfactant Compositions

Example Example Number Rf-Surfactant Rf-Synergist Number Rf-Surfactant Rf-Synergist 39 A4 B3 53 A26 B20 40 A5 B4 54 A27 B1 41 A6 B5 55 A28 B15 42 A7 B7 56 A29 B16 43 A9 B8 57 A31 B1 44 A10 B10 58 A32 B1 45 A11 B11 59 A33 B1 46 A19 B13 60 A34 B1 47 A20 B6 61 A35 B1 48 A21 B6 62 A36 B1 49 A22 B17 63 A37 B1 50 A24 B19 64 A38 B1 51 A25 B20 65 A39 B1 52 A26 B21 66 A43 B1 Examples 67-95.

The following tables summarize the results of measurements on example systems of individual anionic fluorochemical surfactants (Table 8) and surfactant/synergist systems (Table 9). Table 10 demonstrates the effect of varying amounts of magnesium.

In preparation for the testing reported in Table 8 solutions of the named surfactants were prepared at 0.1% in distilled water and their surface tensions were measured using the Cenco-Du-Nuoy ring tensionmeter after 5 minutes equilibration. To a fresh aliquot of that solution a stoichiometric amount of magnesium sulfate was added and the surface tension of each solution was again measured. Table 8 shows the depression of the surface tension achieved by using the magnesium salt. TABLE 8

Surface Tension (dynes/cm) Example Number Rf-Surfactant As Is With Magnesium Added Change 67 F-l 26.0 21.5 -5.5 68 F-2 20.4 w 18.3 -2.1 69 F-10 26.0 21.4 -5.6 70 F-5 18.3 17.9 -0.4 71 F-6 19.3 18.8 -0.5 72 A-12 24.9 18.8 73 A-1 28.9 21.4 -7.5 74 A-8 29.6 19.7 75 A-3 28.2 19.7 -8.5 Table 9 shows that when magnesium sulfate is employed in a surfactantsynergist combination, the surface tension is further depressed.

TABLE 9

Surface Tension (Dynes/cm) Example Rf-Surfactant/ Number Synergist Ratio As Is With Magnesium Added Change 76 F-1/B6 5:1 18.4 15.7 -2.7 77 F-2/B6 5:1 18.8 17.1 -1.7 78 F-10 31/B6 5:1 22.8 20.0 -2.8 79 F-5 ZA/B6 5:1 17.1 16.9 -0.2 80 F-6/B6 5:1 17.9 17.9 -0 81 A-12/B6 5:1 21.6 16.1 -5.5 82 A-1/B6 5:1 21.4 17.1 -4.3 83 A-8/B6 5:1 23.4 15.6 -7.8 84 A-1/B6 5:1 21.4 17.3 -4.1 85 A-1/B9 1.5:1 18.3 15.0 -3.3 86 A-1/B12 1.5:1 23.3 15.8 -7.5 87 A-1/B14 5:1 21.9 18.3 -3.6 88 A-1/B18 5:1 20.1 16.6 -3.5 89 A-1/B19 5:1 19.4 18.8 -0.6 90 A-1/B21 5:1 18.5 16.2 -2.3 91 A-3/B6 5:1 19.0 15.8 -3.2 Table 10 shows the relationship between the relative amounts of magnesium salt and surfactant employed and the surface tension depression achieved. The surfactant and the surfactant/synergist concentrations were held constant at 0.01 and the ratio of surfactant to synergist was 6:1.

TABLE 10

Surface Tension Depression (dynes/cm) Example Surfactant/ Number Magnesium Level Synergist (A3/B4) 92 None -0 93 0.2 Equivalents 3.8 94 1 Equivalent 4.0 95 5 Equivalents 4.8

Claims

It is pointed out that in our Application No. 79 22282 (Serial No. 1,591,293) we describe and claim a method of improving the surface tension properties of a solution of a cationic, anionic, non-ionic, amphoteric or mixed function fluorinated surfactant which comprises adding to the solution a magnesium salt as well as the compositions of fluorinated surfactant and magnesium salt. WHAT WE CLAIM lS:-

1. A method of improving the surface tension properties of a solution of cationic, anionic, non-ionic, amphoteric or mixed function fluorinated surfactant which comprises preparing the said surfactant solution with a fluorinated synergist of the formula (R,)nTmZ wherein Rf is a straight or branched chain perfluoroalkyl of 1 to 18 carbon atoms or said perfluoroalkyl substituted by perfluoroalkoxy of 2 to 6 carbon atoms, n is 1 or 2, T is a divalent group -R3- or a group -R3SCH2CHR1- where R3 is straight or branched chain alkylene or haloalkylene of 1 to 12 carbons, arylene of 6 to 12 carbons, alkylenethioalkylene or alkyleneiminoalkylene of 2 to 12 carbons where in said imino group the nitrogen atom is secondary or tertiary and R, is hydrogen or alkyl of 1 to 12 carbons, Z is a neutral or a polar group which is -CONR1R2, -CN,-CONR1COR2, -SO2NR1R2, -R3(O2CR1) or -CO2R1 where R, and R2 are independently hydrogen, alkyl of 1 to 12 carbons or alkyl substituted with one or more -OH, -COCH3, -SH or -CONH(CH3), and R3 is as defined above, m is 0, 1 or 2, the fluorinated synergist having a solubility in water at 250C. below 0.01% by weight, and, optionally, a magnesium salt.

2. A method according to claim 1 in which the fluorinated synergist is added to a solution of the fluorinated surfactant.

3. A method according to claim 1 or 2, in which the fluorinated surfactant is of the formula (Rf)nAmQ wherein Rf, n and m are as defined in claim 1, Q is a water solubilizing group which is an anionic, cationic, non-ionic or amphoteric moiety or a combination of such moieties, A is a multivalent linking group.

4. A method according to claim 3 in which A is alkylene of 1 to 12, arylene, alkyl substituted phenylene or the group CeH4YC6H4 where Y is alkylene of 1 to 4 oxygen or sulfur, sulfonamidoalkylene or carbonamidoalkylene.

5. A method according to claim 4 in which A is alkylene of I to 4 carbon atoms or the group C ,H4YC"H4 where Y is methylene.

6. A method according to claim 4, wherein A is phenylene.

7. A method according to any one of claims I to 6, characterised in that the fluorinated groups in both the synergist and the surfactants are perfluoroalkyl of 5 to 12 carbon atoms.

8. A method according to any one of the preceding claims in which the fluorinated synergist but not the magnesium salt is used.

9. A method according to any one of claims I to 7 for improving the surface tension properties of an anionic fluorinated surfactant solution, which comprises preparing the solution with the fluorinated synergist and the magnesium salt.

10. A method according to claim 9 for lowering the surface tension of an aqueous solution of an alkali metal salt of said anionic fluorinated surfactant which comprises adding thereto 0.1 to 5 equivalents per equivalent of the surfactant of a magnesium salt which is magnesium sulfate, magnesium nitrate, magnesium chloride or magnesium acetate.

11. A metnod according to any one of claims I to 7, 9 and 10 in which the magnesium salt is magnesiurn sulfate.

12. A method according to any one of the preceding claims in which the anionic fluorinated surfactant is a carboxylic acid or salt thereof, sulfonic acid or salt thereof, a phosphonate, a phosphate or a related phosphoro derivative or salt thereof.

13. A method according to claim 1 substantially as described in any one of Examples 1 to 24, 26, 27, 29, 30, 32 to 34 and 36 to 66.

14. A method according to claim I substantially as described in any one of Examples 76 to 95.

15. A solution of a fluorinated surfactant whenever prepared by a method as claimed in any one of claims 1 to 14.

16. A solution as claimed in claim 8.

17. A surfactant composition which contains a mixture of a cationic, anionic, non-ionic, amphoteric or mixed function fluorinated surfactant, component (1) which is a fluorinated synergist of the formula (Rf)nTmZ wherein Ref is a straight or branched chain perfluoroalkyl of 1 to 18 carbon atoms or said perfluoroalkyl substituted by perfluoroalkoxy of 2 to 6 carbon atoms, n is 1 or 2, T is a divalent group -R3- or a group -R3SCH2CHR1- where R3 is straight or branched chain alkylene or haloalkylene of 1 to 12 carbons, arylene of 6 to 12 carbons, alkylenethioalkylene or alkyleneiminoalkylene of 2 to 12 carbons where in said imino group the nitrogen atom is secondary or tertiary and R1 is hydrogen or alkyl of 1 to 12 carbons, Z is a neutral or a polar group which is -CONR1R2, -CN, -CONR1COR -SO2NR1R2, -R3(O2CR1) and -CO2R1 where R1 and R2 are independently hydrogen, alkyl of 1 to 12 carbons or alkyl substituted with one or more -OH, -COCH3, -SH or -CONH(CH3), and R2 is as defined above, m is 0, 1 or 2, said synergist having a solubility in water at 25 C. below 0.01% by weight, and, optionally component (2) which is a magnesium salt.

18. A surfactant composition according to claim 17 in which the fluorinated surfactant is of the formula (Rf)nAmQ wherein R,, n and m are as defined in claim 17, Q is as defined in claim 3 and A is as defined in claim 3, 4 or 5.

19. A surfactant composition according to claim 17 or 18 in which the fluorinated groups in both the synergist and the surfactants are perfluoroalkyl of 5 to 12 carbon atoms.

20. A surfactant composition according to any one of claims 17 to 19 which contains component (1) but not component (2).

21. A surfactant composition according to any one of claims 17 to 19 which contains an anionic fluorinated surfactant the fluorinated synergist and the magnesium salt.

22. An aqueous surfactant composition according to claim 21 which contains an alkali metal salt of the anionic fluorinated surfactant and 0. I to 5 equivalents per equivalent of the surfactant of a magnesium salt which is magnesium sulfate, magnesium nitrate, magnesium chloride or magnesium acetate.

23. A surfactant composition according to claim 22 which contains magnesium sulfate.

24. A surfactant composition according to any one of claims 17 to 23 in which the anionic fluorinated surfactant is a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphonate, a phosphate or related phosphoro derivative or salt thereof.

25. A surfactant composition according to claim 17 substantially as described in any one of Examples 1 to 24, 26, 27, 29, 30, 32 to 34 and 36 to 66.

26. A surfactant composition according to claim 17 substantially as described in any one of Examples 76 to 95.