Fluorinated Nonionic Surfactants

U.S. Pat. No. 3,621,059 describes amides derived from hexafluoropropylene oxide polymer acids and polyalkylene oxide having the formula: ##STR3## wherein R.sub.f is a perfluoroalkyl radical having one to eight carbon atoms, n is an integer of zero to 100; R.sup.1 is an alkylene radical having two to 12 carbon atoms; R.sup.2 is hydrogen or an alkyl radical having one to four carbon atoms; R.sup.3 is hydrogen or an alkyl radical having one to four carbon atoms, at least one of R.sup.2 and R.sup.3 in each repeating unit being hydrogen; y is an integer of one to 60; R.sup.4 is hydrogen or an alkyl radical having one to four carbon atoms, and R.sup.5 is hydrogen or an alkyl radical having one to six carbon atoms. These amides function efficiently as surfactants and emulsifying agents. All these surfactants are derived from hexafluoropropylene oxide.

Albrecht et al. in the U.S. Pat. No. 2,915,554 disclose perfluoro alkanesulfonamides having the formula: ##STR4## in which R.sub.f is a perfluoroalkyl group having from four to twelve carbon atoms; R.sup.6 is a member of the group consisting of hydrogen, lower alkyl radicals and R.sup.7 and R.sup.7 in a polyoxyalkyl group having the formula: ##STR5## in which m is an integer from 2 to 3, n is a number from 2 to about 20, and each R" is hydrogen or a methyl radical.

These sulfonamides serve as surface-active agents. The presence of an SO.sub.2 group is required in all cases.

Other nonionic fluorochemical surfactants have been described in German Offenlegungsschriften Nos. 2215388; 2261681.

It has now been found that a large variety of useful nonionic fluorinated surfactants can easily be prepared without the necessity of an alkylation reaction and without the need for preparing an intermediate perfluoroalkyl substituted acid, by base catalyzed addition of an R.sub.f -substituted thiol to the maleic or fumaric half ester or half amide containing a hydrocarbon, polyethylene oxide or polysiloxane group in the ester or amide moiety. It is a further advantage, and contributing to the superiority of these novel compounds, that they can be especially tailored for specific systems, that is, their compatibility with a given system, be it aqueous or organic, can be optimized, and even structural elements can be matched, by selecting the proper nonionic derivative for the synthesis.

Synthesis of these novel surfactants is conveniently carried out in two steps: the first involves the ring-opening reaction of maleic anhydride with a polyether, polyester diol, diamine or polysiloxane derivative which may be either an alcohol or a primary amine [and may also contain hydrophobic segments such as aliphatic or aromatic hydrocarbon groups or polypropylene oxide segments]. The second step consists of a base catalyzed addition of a perfluoroalkyl substituted thiol onto the maleic double bond, carried out in a suitable solvent or in bulk.

The novel surfactants contain a carboxy group and are soluble in dilute mineral acid solution and thus behave like non-ionic surfactants. At basic pH, the carboxy groups contribute to increased solubility.

This invention is directed to the perfluoroalkyl substituted half esters and amides having the formula: ##STR6## wherein

R.sub.f is straight or branched chain perfluoroalkyl of 4 to 18 carbon atoms or said perfluoroalkyl substituted by perfluoroalkoxy of 2 to 6 carbon atoms,

R.sup.1 is branched or straight chain alkylene of 1 to 12 carbon atoms, alkylenethioalkylene of 2 to 12 carbon atoms, alkyleneoxyalkylene of 2 to 12 carbon atoms or alkyleneiminoalkylene of 2 to 12 carbon atoms where the nitrogen atom contains as a third substituent, hydrogen or alkyl of 1 to 6 carbon atoms,

X is oxygen or NH,

y is 1 or zero,

Q is a polyether or polyester diradical moiety having a molecular weight of 300 to 5000 or a polysiloxane having 5 to 80 repeating units, and

A is hydrogen, hydroxyl, amino, alkoxy of 1 to 21 carbons, phenoxy, alkylphenoxy of 7 to 20 carbons, dialkylamino where each alkyl has 1 to 18 carbons or the group ##STR7##

Preferably R.sub.f is a straight or branched chain perfluoroalkyl of 6 to 12 carbon atoms, R.sup.1 is alkylene of 1 to 6 carbons and most preferably ethylene, y is zero, Q is a polyalkylene oxide having from 10 to 50 repeating units, such as polyethylene oxide, and A is hydroxyl, amino, methoxy or alkylphenoxy of 7 to 15 carbon atoms.

The compounds of this invention can be conveniently prepared by a two-step method. The first step consists of a condensation reaction of an alcohol, diol, amine or a diamine with maleic or itaconic anhydride to yield intermediates of formulae ##STR8##

Said intermediates can also be prepared through transesterification with lower-alkyl esters of maleic, fumaric or itaconic esters such as mono- and dimethyl esters of maleic fumaric or itaconic acids. The most useful starting material for the intermediate of structure III is maleic anhydride. Methyl-maleic acid and chloromaleic acid derivatives can be used in the process of this invention, but give unpractically low yields of the desired end-product.

In the second step a base catalyzed addition reaction of perfluoroalkyl alkylene thiol R.sub.f --R.sup.1 --SH and an intermediate of formula III or IV is carried out.

The group Q is a polyether, polyester or siloxane diradical. Following are illustrative examples of polyether diradicals:

Examples of polyester-diol diradicals are those derived from diacids and diols, for instance alkylene glycol polyadipate, polysebacate, polyisophthalate, polyorthophthalate, polyterephthalate, polymaleate, polyglutarate and the like; such polyester diols may be based on a mixture of several diols and diacids and are commercially available as polyurethane prepolymers in a molecular weight range from 400-5000.

Examples of polysiloxanes are: ##STR12##

Examples of the alcohols, diols and amines useful in the preparation of intermediates III and IV are listed below:

polyethylene oxide, MW 200-5000

polypropylene oxide, MW 200-5000

methoxy polyethylene oxide, MW 500-2500

poly-tetramethylene oxide, MW 3000-6000

poly(ethylene-co-propylene oxide) block polymers (PLURONICS and Reverse PLURONICS from BASF-Wyandotte)

ethoxylated alkyl phenol (IGEPALS-TRITONS from GAF Corp. and Rohm and Haas Corp.) where alkyl group is octyl or nonyl and the ethoxylated group contains from 5 to 50 ethylene oxide units

ethoxylated primary and secondary amines (Ethomeen, Armour Chemicals) of 8 to 20 carbons

ethoxylated fatty acids and amides (Ethomids, Armour Chem.) of 8 to 20 carbons

alkoxylated alcohols and diols of 8 to 20 carbons

bis-2-amino propyl)ethers of polyethylene oxide and polypropylene oxide (Jeffamine ED and D; Jefferson Chem 6).

Siloxane diols and triols (Code 1248, Q4- 3557m Q4- 3667; DOW Corning Corp.)

Ethoxylated mercaptans of 8 to 20 carbons

The perfluoroalkyl thiols employed in the preparation of the compounds of this invention are well known in the prior art. For example, thiols of the formula R.sub.f --R.sup.1 --SH have been described in a number of U.S. Pat. Nos. including 2,894,991; 2,961,470; 2,965,677; 3,088,849; 3,172,190; 3,544,663 and 3,655,732.

Thus, U.S. Pat. No. 3,655,732 discloses mercaptans of formula

where

R.sup.1 is alkylene of 1 to 16 carbon atoms and R.sub.f is perfluoroalkyl and teaches that halides of formula R.sub.f --R.sup.1 --hal are well known; reaction of R.sub.f I with ethylene under free-radical conditions gives R.sub.f (CH.sub.2 CH.sub.2).sub.a I while reaction of R.sub.f CH.sub.2 I with ethylene gives R.sub.f CH.sub.2 (CH.sub.2 CH.sub.2).sub.a I as is further taught in U.S. Pat. Nos. 3,088,849; 3,145,222, 2,965,659 and 2,972,638.

U.S. Pat. No. 3,655,732 further discloses compounds of formula

where

R.sup.1 and R.sup.11 are alkylene of 1 to 16 carbon atoms, with the sum of the carbon atoms of R.sup.1 and R.sup.11 being no greater than 25; R.sub.f is perfluoroalkyl of 4 through 14 carbon atoms and X is --S-- or NR'" -- where R'" is hydrogen or alkyl of 1 through 4 carbon atoms.

U.S. Pat. No. 3,544,663 teaches that the mercaptan

where

R.sub.f is perfluoroalkyl of 5 to 13 carbon atoms, can be prepared by reacting the perfluoroalkyl alkylene iodide with thiourea or by adding H.sub.2 S to a perfluoroalkyl substituted ethylene (R.sub.f --CH.dbd.CH.sub.2), which in turn can be prepared by dehydrohalogenation of the halide R.sub.f --CH.sub.2 CH.sub.2 --hal.

The reaction of the iodide R.sub.f --R.sup.1 --I with thiourea followed by hydrolysis to obtain the mercaptan R.sub.f --R.sup.1 --SH is the preferred synthetic route. The reaction is applicable to both linear and branched chain iodides. Many useful perfluoroalkoxyalkyl iodides are described in Australian Application No. 36868 filed Apr. 24, 1968, of general formula

where

m is 1-3.

Particularly preferred herein are the thiols of formula

where

R.sub.f is perfluoroalkyl of 6 to 12 carbon atoms. These R.sub.f -thiols can be prepared from R.sub.f CH.sub.2 CH.sub.2 I and thiourea in very high yield.

Illustrative examples of preferred perfluoroalkylalkylenethiols are:

especially preferred perfluoroalkylalkylenethiols are:

and mixtures thereof.

Synthesis of the novel nonionic surfactants is most conveniently carried out in two steps: the first step consists of reacting the cyclic anhydride, most commonly maleic anhydride, with the hydroxy or amino substituted nonionic compound either in bulk or in a common dry and aprotic solvent; useful solvents include ketones, such as acetone and methylethyl ketone; ethers, such as diethylether or ethylene glycol - dimethylether, or tetrahydrofuran; esters, such as ethyl acetate or methyl Cellosolve acetate; amides, such as dimethylformamide or N-methyl pyrrolidone. While amines react rapidly at room temperature, hydroxy compounds have to be heated for several hours to 50.degree.-100.degree. C. The second step involves addition of the perfluoroalkyl alkylene thiol to the intermediate maleic half ester or half amide in the presence of basic catalysts, such as triethylamine, pyridine, or tetramethyl ammonium hydroxide. Addition of the thiol to the mixture often leads to heterogeneous, 2-phase system, which will turn into a homogeneous solution, as the reaction proceeds. This reaction step is preferably carried out between 30.degree. and 75.degree. C. under a nitrogen blanket and with good stirring.

The compounds of this invention can also be prepared by reversing the order of reactions described above; that is, first carry out the base catalyzed addition of a perfluoro substituted thiols to maleic anhydride followed by the ring opening with the hydroxy or amino substitute nonionic compound.

Such fluorochemical surfactants are useful to improve or impart properties such as: wetting, penetration, spreading, leveling, 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 inferred for other applications.

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 mound release agents, for silicones, etc.

In refractory processes

As an anti-mist film former

Additive for elimination of trapped air in plastic laminates

Wetting agent for resin molds for 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, anti-cratering

Adjuvant for resin etchant

Mold release agent, demoulding agent

Retarder for plasticizer migration or evaporation

Internal antistatic agent for polyolefins

Antiblocking agent for polyolefins

As a film evaporation inhibitor for gasoline, jet fuel, solvents, hydrocarbons

In extreme pressure EP lubricants

Soil release and soil proofing agent

Oil/water repellent textile and leather treatment

Wetting agent to improve coverage and penetration of pores of substrates

Anti-foaming 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

Leveling, anti-cratering 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 non-reactive

Pigment grinding aid to promote wetting, dispersion, color development

Foam generator substance for the application of dyes, inks

Electrolytic conversion coatings

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

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 anti-blocking agent

Wetting agent for leaching copper ores and as a fresh flotation agent

To promote ore wetting and quicker breaking of the protective oxide layer

Improve the properties and penetration of anti-microbial agents

Improve the properties of biochemicals, biocides, algicides, bacteriocides, and bacteriostats

Improve the strength, homogeneity, and reduce the permeability of encapsulated materials

Emulsify fluorochemical blood substitutes

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 desalination

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

Wetting agent for fighting forest fires

Ingredient of AFF, aqueous film forming extinguishing agents

Component of fluoroprotein foams

Additives to dry chemical extinguishing agents

Agent in aerosol-type extinguishers

Wetting agent for sprinkler water

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 wases

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 supression

For acidic concrete cleaners

Bubble foamer for air tracing, in ventilating systems

Rinse-aid for dishwashing

Liquid polishing compositions

Floor polish leveling 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

Printing ink additive for ink flow and leveling, 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, leveling, anti-cratering assist agent

Surfactant for developer solutions

Photoemulsion stabilizer

Prevent photo-lubricant agglomeration

Coating aid in the preparation of multiple 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

The examples below are presented for illustrative purposes only and do not limit the scope of the invention. In the examples the surface tension was measured with a DuNouy tensiometer at 0.1% concentration in water at 25.degree. C.

Synthesis of: ##STR14##

2.5 g (0.0255 mol) maleic anhydride in 2.5 g methyl-ethyl ketone were added to 25 g (0.025 mol) polyethylene oxide of molecular weight MW=1000 and stirred for 12 hours at 75.degree. C. under a nitrogen blanket. At this time, infrared analysis showed no anhydride bands left at 1780 cm.sup.-1 and 1850 cm.sup.-1.

11.8 g perfluoroalkyl-ethylmercaptan* (0.025 mol) of average molecular weight 478 were added together with 0.2 g triethylamine as catalyst (0.002 mol) and the mixture stirred for 12 hours at 50.degree. C. The initially opaque white mixture turned clear after three hours. The clear solution was dried in vacuo at 80.degree. C. for 5 hours. The product is a soft wax which is soluble in water.

Using the procedure of Example 1, compounds of structure ##STR15## were prepared with hydroxy compounds listed below.

Surface tension was measured for each sample, including Example 1 for a 0.1% solution in water.

Using the procedure of Example 1, compounds of structure: ##STR17## was prepared with the amino compounds listed below.

Maleic anhydride (0.0255 moles, 2.5 g) dissolved in 10 g acetone was added to Carbowax-600 (0.0255 moles, 15.3 g) and stirred overnight with triethylamine catalyst (2.5 moles %).

Infrared spectrum showed no anhydride bands left at 1780 cm.sup.-1 and 1850 cm.sup.-1.

1,1,2,2-tetrahydroperfluorooctyl mercaptan (0.0255 m, 9.64 g) was added and the reaction was stirred at room temperature for 2 days before TLC showed no unreacted mercaptan. The clear solution was dried under vacuum to give 23.0 g of a clear white oil (83.8% yield).

Infrared analysis was consistent for the structure.

Surface tension of a 0.1% solution in water was 27.7[dynes]/cm.

Maleic anhydride (0.0255 moles, 2.5 g) was added to Jeffamine ED-900 (0.01275 moles, 11.86 g) in 10 g acetone and the reaction was stirred for 24 hours (IR shows no anhydride bands at 1780 cm.sup.-1 and 1850 cm.sup.-1).

1,1,2,2-tetrahydroperfluorooctyl mercaptan was added and the reaction was stirred overnight at room temperature. TLC showed no traces of unreacted mercaptan.

The clear yellow solution was dried under vacuum to give 26.17 g of a clear yellow viscous oil (99.7% yield).

Infrared analysis was consistent for the structure.

A 0.1% solution in water together with 0.1% Triton X-100 had a surface tension of 23.8[dynes]/cm.

Example 1 is repeated using the following R.sub.f -thiols: ##STR21## to give the corresponding water soluble surfactants.