US3431140A - Oil and water repellent textiles - Google Patents

Description

United States Patent 3,431,140 OIL AND WATER REPELLENT TEXTILES Michael Thomas Beachem, Somerset, N.J., assignor to American Cyanamid Company, Stamford, Conn., a

Corporation of Maine N0 Drawing. Filed June 30, 1965, Ser. No. 468,553 U.S. Cl. 117-121 4 Claims Int. Cl. D06m /30, 15/36 ABSTRACT OF THE DISCLOSURE Oil and Water repellency are imparted to textiles by applying about 0.25% to 5% of a poly-bis(polyfluoroalkoxy)phosphonitrile of the formula OR I l P =N Lie 1.

where R is alkyl (C C substituted by at least two fluorine atoms on each carbon atom except the one attached to oxygen and n is a number between and 12,000.

This invention relates to a method of imparting oil and water repellency to textile materials. The invention further relates to textile materials having improved oil and water repellent properties. More particularly, the invention relates to a method of imparting oil and water repellency to textile materials employing a poly[bis(polyfluoroalkoxy)phosphonitrile] and to the textile materials so treated.

Many methods and materials useful for imparting durable water repellency to textile materials are known. The materials useful for imparting water repellency, however, are generally not effective for imparting oil repellency since surface energy (surface tension) requirements differ for oil repellency. Moreover, chemicals having the proper surface energy characteristics to be considered for use as oil. repellents for textiles do not always impart oil repellency thereto because they lack the proper bonding characteristics, i.e., they do not properly orient on the textile surface nor have the ability to become durably aflixed to the treated textile.

Polyfluorinated carbon chains possess the required surface energy characteristics for use as oil and water repellents on textiles. Thus, compounds containing such chains and a hydroxyl or sulfonic acid group on one end have been chemically bonded to acrylic acid to form esters or to an aminoalkoxyacrylate to form sulfonamides. Subsequent emulsion polymerization of such reaction product monomers gives rise to polymers which impart oil and water repellency when applied to textile materials.

For imparting effective oil and water repellency to textile materials, it has been said that the fluorocarbon chain of the treating agent must have a minimum of four fluorinated carbon atoms, the carbon atoms of the chain must be completely fluorinated and the chain must be terminated by a -CF group. Moreover, the fluorinated carbon chain must be chemically attached to a backbone or bonding group which provides the physical or chemical bond between the treating agent and the textile material substrate. This backbone or bonding group influences the durability of the oil and water repellency in that it largely determines the degree of orientation and packing of the fluorinated carbon chains on the textile material. See Grajeck and Petersen, Oil and Water Repellent Fluorochemical Finishes For Cotton, Textile Research Journal, vol. 32, April 1962, pp. 320-331.

A textile treating agent has now been discovered which 3,431,140 Patented Mar. 4, 1969 not only imparts excellent oil and water repellency to textile materials but also overcomes certain disadvantages of the prior art fluorochemical treating agents. In particular, a class of oil and water repellents for textile materials has been discovered which is effective even though the fluorinated carbon chains contain less than four carbon atoms and are incompletely fluorinated.

Since these new textile finishing agents may be prepared from more simple fluorocarbon compounds, they offer the advantage of not requiring expensive and degradative fluorination processes which often result in excessive cost of manufacture of the treating agent. Moreover, the new finishing agents are useful for treatment of synthetic fiber textiles as well as cotton or cotton-synthetic fiber blends. A further advantage is avoidance of the cost and complexities of emulsion polymerization since the new class of finishing agents may be prepared by reacting a prepolymer with a fluoroalcohol.

These and other features and advantages of the invention will become more apparent from the detailed description hereinafter.

Accordingly it has been discovered that excellent oil and water repellency is imparted to textile materials by treatment with polymeric compounds containing polyfluoro carbon chains chemically bonded to phosphonitrile radicals to form a poly[bis(polyfiuoroalkoxy)phosphonitrile] or polymer mixture thereof represented by wherein n is a positive integer of at least about 25, preferably in the range of 25 to about.12,000, and R is an alkyl group, straight or branched chain, containing 2 to 18 carbon atoms inclusive. Said alkyl group is substituted by fluorine such that 0 to 2 fluorine atoms are attached to the carbon atom alpha to the oxygen atom and at least 2 fluorine atoms are attached to each of the other carbon atoms. From the foregoing it will be evident that the simplest value for R is -CH CF H. The textile treating agents of the invention thus include compounds wherein the fluorinated carbon chain contains less than four carbon atoms and is less than perfiuorinated and wherein the terminal carbon atom or atoms are substituted by two or three fluorine atoms.-

While phosphonitrile chloride polymers and polyfluorinated alcohols are known, the application of the polymeric product obtained by reaction of these two entities to textile materials to impart oil and water repellency is novel and provides substantial advantages over known treating agents as already described. Thus, the capacity of a single polyfluorinated carbon atom in the alkyl chain of the compounds of the present invention to produce effective oil repellency where heretofore four or more polyfluorinated carbon atoms have been employed, has the two-fold advantage of permitting the use of short, more economical polyfluorinated carbon chains and, at the same time, permits use of abundant and readily produced polyfluorinated alcohol reactants.

A further substantial advantage of the invention is the economy and facility of preparation of the treating agents. Thus, the known water and oil repellents result from emulsion polymerization of monomers containing the polyfluorinated carbon chains. Such polymerization is difficult to initiate and control, results in too wide a range of molecular weight in the polymer, and leads to residual monomer as well as hydrolysis products. Also, purification of the emulsion polymerization product is impractical. The present invention, however, makes use of a preformed backbone or bonding polymer to which are thereafter attached the polyfluorinated carbon atoms. No emulsion polymerization is required and thus the problems of emulsion polymerization are avoided or minimized.

The poly[bis(polyfluoroalkoxy)phosphonitriles] used in the method of the invention are prepared starting with polyphosphonitrile chlorides obtained by reaction and polymerization of phosphorus pentachloride and ammonium chloride by well-known methods. The resulting polymer is then reacted with a slight excess, e.g., 125% molecular equivalent, of a lithium, sodium, potassium, magnesium or calcium salt of a polyfiuoroalcohol having the desired polyfluorinated carbon chain to produce the modified polymer. The resultant product is a polymeric mixture. This polymeric mixture as well as the process for preparation is the subject of US. Patent No. 3,370,- 020 of H. R. Allcock and R. Kugel. Although the polymeric mixture and method of preparation form no part of the present invention, the disclosure of the aforementioned patent is incorporated herein by reference for purposes of completeness.

One diiference between the treating agents of the instant application and those disclosed and claimed in the aforementioned patent is the wider range of molecular weight of the former. Thus n of the formula in the aforementioned patent ranges from about 350 to 1500, whereas n in the present application may range as low as about 25, the precise range and upper limit for optimum performance being only a matter of choice to one skilled in the art, given the present disclosure.

The higher molecular weight range of the polymeric mixture of the aforementioned patent is obtained by fractionally precipitating in a. conventional manner the polymeric material resulting from reaction of the fluoroalcoholate with the preformed phosphonitrilic chloride polymer so as to remove lower molecular weight polymer from the polymeric mixture. For purposes of the present invention, the fractional precipitation disclosed in the aforementioned patent need be carried out only to the extent required for removal of very low molecular weight polymers, i.e., polymers wherein n is less than about 25, from the polymeric mixture. Other than the extent to which fractional precipitation is effected, the manner of preparation of the treating agents of the present invention is substantially the same as disclosed in said aforementioned patent.

It follows from the above that for purposes of imparting oil and water repellency to textile materials, relatively crude polymeric reaction product mixtures may be employed. However, if desired the polymeric mixture may be further fractionally precipitated and purified so as to obtain treating agents of higher and narrower molecular weight range.

For the success of the method of the invention it is important that the treating agents be substantially free of chlorine since such presence seriously impairs performance and causes textile damage. The use of excess metal polyfluoroalcoholate insures freedom from chlorine by removing the chlorine in the polyphosphonitrilic chloride reactant.

The alcohols that may be used to react with polyphosphonitrilic chloride include singly or in admixture 2,2-difluoroethanol;

2,2,2-trifluoroethanol;

2,2,3,3,3-pentafluorol-propanol;

1, 1,1,3 ,3 ,3 -hexafluoro-2-propanol;

1, l,1,2,3,3,3-heptafiuoro-2-propanol; 2,2,3,3,4,4,4-heptafluorol-butanol;

2- (trifluoromethyl) -2,3,3 ,S-tetrafluorol-propanol 2,2,3,3,4,4,5,5,5-nona.fluorol-pentanol; 3-(trifluoromethyl)-2,2,3,4,4,4-hexafluoro-l-butanol; 2,2,3,3,4,4,5 ,5 ,6,6,6-undecafiuorol-hexanol; 4-(trifiuoromethyl)-2,2,3,3,4,5,5,5-octafiuoro-l-pentanol; 2,2,3,3,4,4,5 ,5 ,6,6,7,7,7-tridecafluorol-heptanol 4 5-(trifluoromethyl)-2,2,3,3,4,4,5,6,6,=6-decafluoro-1- hexanol; 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafiuoro-1-octanol; 6-(trifiuoromethyl)-2,2,3,3,4,4,5,5,6,7,7,7-dodecafiuorol-heptanol; 1,l-dihydroperfluoro-l-dodecanol; 1, 1-dihydroperfluorol-octadecanol;

as well as similar alcohols and isomers including those wherein one of the three fluorine atoms on a terminal carbon atom is replaced by a hydrogen atom.

As indicated above, the molecular weight of the treating agents is not especially critical for imparting oil and water repellency and may vary over wide limits. Thus, the weight average molecular weights may range from about 6 ,000 to 3,000,000 or higher, preferably from about 1,000,000 to 2,500,000, as determined by intrinsic viscosity measurements in acetone at 30 C.

The poly[bis(polyfiuoroalkoxy)phosphonitrile] polymeric mixture is applied to the textile material by first preparing a solvent solution or aqueous dispersion of the treating agent. Suitable solvents include acetone, tetrahydrofuran, ethyl acetate, ethylene glycol dimethyl ether, methyl ethyl ketone, dimethylformamide, and the like. Aqueous dispersions may be made by any convenient procedure, many being known in the art. Choice of dispersant can influence performance and while anionic dispersions are best for W001 at low pH, cationic or non-ionic dispersions are best for other fiber types as well as wool at high pH. In general, such dispersants should be chosen not only for their power to disperse the polymer but also such as not to afiect the oil and water repellency. Convenient methods of preparing aqueous dispersions include dissolving the polymeric mixture in a solvent and then adding the dispersant and water or dissolving the polymeric mixture in a solvent, then adding water and thereafter adding dispersants separately to oil and water phases. The details of these and other procedures will be obvious to those skilled in the art given the instant disclosure.

The solvent solution or aqueous dispersion of poly- [bis(polyfluoroalkoxy)phosphonitrile] treating agent is then applied to the textile material by any convenient method such as dipping, padding, spraying, soaking, steeping, and the like, under proper conditions of control. The amount of poly[bis(polyfiuoroalkoxy)phosphonitrile] agent applied will vary from about 0.25% to about 5.0%, based on the dry weight of fabric, depending upon the nature of the textile and polymer, whether or not ancillary agents are employed, the level of effectiveness desired and other factors. A particularly useful range has been found to be from 0.5% to 2.0%, based on the dry weight of the fabric.

The textile materials suitable for treatment may contain singly or in blends of two or more, cotton, viscose, wool, acetate rayon, nylon, polyester, acrylic, polyvinyl chloride, ramie, jute, polypropylene fibers and the like. The textile materials may be in the form of fibers, filaments, yarns, unwoven, woven or knitted fabrics, as well as completed garments or apparel.

Following application of the oil repellent of the present invention, it is necessary only to allow for removal of the application medium to achieve durable oil and water repellency. Such removal may be accomplished at ambient conditions by air drying or at elevated temperatures in ovens circulating hot air. When aqueous dispersions or non-flammable solvent solutions of the treating agents are employed, use of ovens at temperatures up to about 250 F. for about 1 minute, preferably at 225 F. for two minutes, has been found effective. The drying time will vary inversely with the drying temperature. For example, at lower drying temperature, e.g., about F., drying time may be as long as about 4 hours. However, it is desirable to avoid conventional curing conditions since these may adversely aifect oil and water repellency and other fabric qualities.

It is within the scope of the present invention to employ with the oil and water repellents auxiliary additives or finishing agents as desired provided said materials do not interfere with or detract from the oil and water repellent properties.

In order that the present invention may be more completely understood, the following examples are given in which all parts and percentages are parts by weight unless otherwise specified. These examples are set forth primarily for the purpose of illustration and any specific enumeration of detail contained therein should not be interpreted as a limitation on the case except where indicated in the appended claims.

PREPARATION OF POLYMER MIXTURE A Two hundred parts of phosphonitrilic chloride trimer, previously recrystallized from n-heptane, are degassed and sealed in a suitable, thick-walled reaction vessel and heated to 250 C. for 4 hours. Polymerization is terminated at this time since a glass ball, one-half inch in diameter, ceased to flow, when the vessel is inverted, due to the increased viscosity of the molten mass. Termination is effected by cooling the vessel to room temperature. The resulting polymeric mixture is then dissolved in 1000 parts of dry benzene. A solution of sodium 2,2,2-trifluroethoxide is prepared by the slow addition to 81.7 parts of sodium to 355 parts, of 2,2,2-trifiuoroethanol in 1500 parts of diethyl ether. A further 35.5 parts of 2,2,2-trifiuoroethanol are added to complete the reaction. This solution is then added dropwise to the stirred polymer mixture solution and the resulting mixture is stirred and refluxed for 14 hours and stirred at 25 C. for 40 hours. The mixture is then neutralized with concentrated hydrochloric acid and the solids are filtered off, washed with methanol and water and dried. The residue is a polymer mixture. It is dissolved in acetone, filtered through a fritted filter disc, and precipitated into benzene. This procedure is repeated twice.

The final purified polymer mixture is a flexible, white solid with a softening point of 243 C. and a crystalline melting point of 238 C. The glass transition temperature is 18 C., and the T value is 405 C. in air and 420 C. in nitrogen. The intrinsic viscosity, in acetone at 30 C., is 1.92 dl./g., the number average molecular weight by osmotic pressure is 90,000 and the weight average molecular weight is 1,700,000i500,000 corresponding to an n value of about 6,000 in the structural formula representing the finishing agents of the present invention.

The infrared spectrum shows a peak at 1265 cm? which is indicative of P=N bonding, while the nuclear magnetic resonance P spectrum shows a single peak at +8.9 p.p.m. This is consistent with a linear, phosphonitrilic polymer structure. X-ray diffraction photographs show that the polymer mixture is crystalline.

Analysis.Theory for PNO F C H C.20.6; H, 1.65; N, 5.77; P, 12.76; F, 46.9; Cl, 0. Found: C, 20.28; H, 1.95; N, 5.73;P, 12.99; F, 47.21; Cl, 0.

Example 1 A 5% solution of polymer mixture A in dimethylformamide is applied to white 80 x 80 cotton percale by padding. A microset laboratory padder is employed and a wet pickup of 80% is obtained, depositing 4% solids of polymer on fabric. The treated fabric is dried for two minutes at 225 F. in a hot air circulating oven.

The treated fabric is tested for water repellency in accordance with American Association of Textile Chemists and Colorists Spray Test, Method 22-1952, and for oil repellency by the 3M Test, Textile Research Journal, vol. 32, April 1962, pp. 323324, initially and after a wash in a household washer, utilizing a regular cycle, hot wash-warm rinse setting, employing an anionic-type household detergent and a ballast load. The results obtained are given below.

TABLE I Water Repelleuey Oil Repelleney Fabric Initial Washed Initial Washed Untreated 0 0 0 0 Treated 70 70 70 This example shows that good oil and water repellency is obtained with polymer mixture A notwithstanding the short fluorinated carbon chain.

Example 2 TABLE II Water Repellency Oil Repellency Fabric Initial Washed Initial Washed Percale. 70 70 80 60 Poplin. 80 80 60 0 This example shows that the concentration of polymer required to give good oil and water repellency may be considerably less than shown in Example 1 and varies with fabric type and history. It also shows that oil and water repellency vary independently.

Example 3 A polymeric mixture of substantially the same molecular weight range as polymer mixture A is prepared from a phosphonitrilic chloride prepolymer and l,1,1,3,3,3-hexafluoro-2-propanol in substantially the same manner as described for polymer mixture A. The product, a poly- [bis(hexafiuoroisopropoxy)phosphonitrile], exhibits a critical surface tension of 16.7 dynes/cm., measured as described in J. Colloid Sci. 5, 514 (1950) and Textile Research I. 32, 320-331 (1962), as compared to 19.7 dynes/ cm. for polymer mixture A. Since the oil repellent characteristics of a compound improve as critical surface tension decreases, the polymer of this example imparts substantially equivalent or superior oil and water repellency to fabrics treated with the agent in the manner of Examples l and 2.

Example 4 lZiNl Lin wherein n is an integer of at least about 25 and R is alkyl (C -C substituted by 0 to 2 fiuorine atoms on the 7 8 carbon atom attached to the oxygen atom and by at least References Cited two fluorine atoms on all other carbon atoms. UNITED STATES PATENTS 2. Textile material as in claun 1 wherein R is 3,096,207 7/1963 Cohen 117-121 X CH CH 3. Textile material as in claim 1 wherein R is 5 WILLIAM D- MARTIN, Primary Examiner. CFC! THEODORE G. DAVIS, Assistant Examiner. -g US. Cl. X.R.

4. Textile material as in claim 1 wherein R is --CH CF CF CF @2 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION March 4, 1969 Patent No. 3,431,140 Dated Inventor(s) Michael Thomas Beachem It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the claims Column 7 line 4 Claim 2 "-CH CH d CH CF should T63. 2 3

SIGNED AND SEALED Nov 181969 (SEAL) Attest:

Edward M. Fletcher, Ir.

Gummissioner of Patents Attcsting Offiww WILLIAM E- 'SOHUYLER, JR.