US3031335A - Oil-and water-resistant fabrics and method for their production - Google Patents

Description

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April 24, 1962 L. SEGAL ETAL OIL AND WATER-RESISTANT FABRICS AND METHOD FOR THEIR PRODUCTION Filed Aug. 1, 1958 Perfluoromono-corboxylic Add or Sch Aluminum or Zirconium Sul'i INVENTORS LEON SEGAL LEOPOLD LOEB VERNE W. TRIPP ROBERT L. CLAYTON, JR.

ATTORNEY United States Patent ()fifice 3,031,335 Patented Apr. 24, 1962 OIL- AND WATER-RESISTANT FABRICS AND METHOD FOR THEIR PRODUCTION Leon Segal, Metairie, La., Leopold Loeb, Louisville, Ky., and Verne W. Tripp, Marrero, and Robert L. Clayton, Jr., Metairie, La., assignors to United States of America as represented by the Secretary of Agriculture Filed Aug. 1, 1958, Ser. No. 752,683 18 Claims. (Cl. 117-69) (Granted under Title 35, US. Code (1952), see. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant snblicenses for such purposes, is hereby granted to the Government of the United States of America.

application is a continuation-impart of application Serial No. 663,857, filed June 5, 1957, now abandoned.

This invention relates to stain-resistant fabrics and to a process for producing them. More particularly, it relates to and has the objective of the production of cellulosic fabrics which are resistant to soil, grease, oil, and water borne stains.

It is known that hydrophobic and oleophobic surfaces can be produced by depositing on a base a monolayer of a chromium coordination complex of a fluorocarbon acid.

According to this invention, textile fabrics of improved waterand oil-repellency are produced by a two-step process involving the immersion of the fabric in a solution of a salt, such as, aluminum acetate, zirconium nitrate, or zirconium butoxide, drying the fabric, and then immersing the dried fabric in a solution of a perfiuoromonocarboxylic acid, such as perfiuoro-octanoic acid, perfluorodecanoic acid, or one of their salts, In a prefer-red form, the invention involves the use of the acid dissolved in a highly polar solvent, such as, ethanol.

The resultant product, where a cellulosic fabric is treated, is repellent to both oil and water and is thus highly resistant to water, oil, and grease-borne soil and stains. This effect is due to the presence on the cellulose fiber of an activated substrate (the residue of the water soluble salt) which attracts the carboxylic end' of the acid molecule, leaving a highly oriented surface of CF groups which are both oleophobic and hydrophobic.

The single FIGURE of the drawing shows an exaggerated view of a transverse cross section of a fiber treated according to this invention. As illustrated, the fiber has a first coating of an aluminum or zirconium salt and a coating, over the first one, of the perfluoromonocarboxylic acid or one of its salts.

Where an acidic salt, such as, zirconium nitrate, is used, it is desirable to neutralize the acidity before treating the fabric with the perfluoro acid. This is accomplished by immersing the fabric, which has been partially dried after treating with the salt solution, in an alkaline solution, such as for example, aqueous ammonia, followed by drying of the neutralized fabric.

The invention is further illustrated by the following examples:

Example 1 A sample of bleached 80 square cotton fabric was steeped in a 1.0 normal aqueous solution of aluminum acetate. After removal from the bath, the impregnated fabric was airdried. A portion of the dried fabric showed a slight degree of hydrophobicity, but no oil-repellency. A second portion of the dried fabric was put aside for use in Example 2, below.

The remaining .dried fabric was immersed for a period of less than 30 seconds in a 0.5% solution of perfiuoro- 2 decanoic acid in alcohol and again air-dried. After drying, the perfluorodecanoic acid treated fabric was found to be extremely hydrophobic and oleophobic according to the tests described in Example 2, below.

Example 2 (a) Drops of water and of mineral oil were placed on the portion of the dried, aluminum acetate impregnated fabric which was set aside in Example 1. The oil spread and penetrated the body of the fabric, indicating no oleophobic properties. The water drops initially assumed a spherical shape, indicating a high contact angle at the solid-liquid interface. However, after a few moments, the water drops also spread and penetrated the body of the fabric, indicating poor water-repellency.

(b) Drops of water and mineral oil were placed on portions of the dried fabric after the treatment with perfluorodecanoic acid. The drops of water remained spherical for a number of hours until they evaporated, while the drops of mineral oil remained spherical indefinitely.

These tests indicate the great waterand oil-repellency produced by the two-step treatment, and also that the hydrophobic effect is not produced by the presence of basic aluminum salts, aluminum hydroxide, and aluminum oxide which are essentially hydrophobic materials.

Example 3 The same procedure as Example 1 was followed except that a 0.2 normal aqueous solution of the aluminum salt was used in the first step. This sample showed substantially the same oiland water-repellency as that of Example 1.

Samples prepared according to Examples 1 and 3 were soiled with synthetic (simulated natural) and also with dry (carbon particle) soils by tumbling in a laboratory soiling device. The soil resistance was evaluated by measuring the light reflectance of these samples as com pared with an unsoiled control and a similarly soiled, untreated control. The reflectance of the unsoiled con trol was found to be 92%. When synthetic soil was used this value dropped to 34% for the untreated sample. Both the treated samples dropped only to 56%. When dry soil was used the control soiled to a reflectance of 36%; that of sample 2 was 52% while that of sample 1 was 58%.

Example 4 In order to minimize the possible degrading effect on the fabric by aluminum acetate, the same procedure as in Example 3 was followed except that 1.5 equivalents of sodium acetate were incorporated into the alcoholic per-fluorodecanoic acid solution. A sample treated in this manner has substantially identical oil, water, and soil resistance as that described for the preceding example. The heat degrading property of the sample was evaluated by heating it for 24 hours at degrees C. An untreated control subjected to this degree of heat exposure lost 11% of its strength as measured on a standard laboratory fabric breaking strength tester. A sample treated with 0.2 normal aluminum acetate alone lost 45% of it sstrength. However the sample treated in the manner described in thisexample suffered a loss of only 20%.

Example 5 The same procedure as Example 1 was followed except that an aqueous solution of 5% zirconium nitrate was used in place of the aluminum acetate solution, and the fabric was neutralized after partial drying by brief immersion in a 0.7% aqueous ammonia solution with subsequent removal and drying. Samples treated in this manner had substantially the same oil, water, and soil resistance as those previously described.

3 Example 6 Cotton sheeting was padded to as close to 100% Wet pickup as possible with aqueous 0.5, 0.25, and 0.1 molar aluminum acetate solutions. The aluminum acetate was prepared by double decomposition of aluminum sulfate and barium acetate. After air-drying, the impregnated fabrics were padded with 1% perfiuorooctanoic acid solution (made up with 95% ethyl alcohol) to as close to 100% wet pick-up as possible (usually 80-90%), airdried, then heated in a forced draft oven at 110 C. for 30 minutes. The dry fabrics were repellent to oils and water. Similar treatments were applied to cotton print cloth with similar results. Treated cotton sateen and treated cotton-rayon whipcord showed low repellency. Material treated with 0.5 molar aluminum acetate alone was not oilor water-repellent.

Example 7 Excellent repellency to oils was obtained by using a solution of perfluoro-octanoic acid on cotton sateen and cotton-rayon whipcord impregnated with 0.5 molar aluminum acetate as in Example 6.

Example 8 0.5 and 1.0% for the perfiuoro-octanoic acid failed to bestow any oil-repellency.

Example 9 Qualitative filter paperwas immersed in solutions made by taking aqueous 0.5 molar aluminum acetate solution in equal volumes with 1%, 0.5%, and 0.1% alcoholic perfluoro octanoic acid solutions and air-dried or ovendried. The treated filter papers were repellent to oils and water placed on the surfaces. Substitution of perfiuorobutyric acid failed to bestow oil-repellency. The 0.5 molar aluminum acetate and the 1% perfiuoro-octanoic acid solutions in volume ratios of 1:1 and 1:4, respectively, were boiled down to a thick white solution or a white waxy paste which was smeared on the filter paper, followed by airand oven-drying. The treated filter papers were highly repellent to oils and water. Oil failed to spread on the surface of the stainless steel blade which was coated with the dried paste, although a drop spread rapidly on an uncoated portion.

Example 10 The clear solution that resulted when 5% zirconium butoxide in isopropanol (prepared by dilution of 50% zirconium butoxide in butanol and stabilized against decomposition by atmospheric moisture by inclusion of acetonyl acetone) was mixed in equal volume with 1% perfiuoro-octanoic acid in isopropanol was applied to qualitative filter paper which was then airand over-dried. The treated paper was highly repellent to oils and water. Whereas untreated filter paper became soaked and had little strength when water was applied, the treated paper similarly exposed to water was not wetted and retained high strength.

We claim:

1. Theprocess for producing a fabric resistant to soil, grease, oil, and water-borne stains which comprises immersing the fabric in a solution of a salt selected from the group consisting of aluminum acetate, zirconium nitrate and zirconium butoxide, drying the fabric, and immersing the dried fabric in a solution of perfiuorodecanoic acid to produce on the fibers of said fabric an active substrate having attracted thereto the carboxyl end of the molecule of said perfiuorodecanoic acid, thereby providing a highly oriented surface of CF groups which is both hydrophobic and oleophobic.

2. The process of claim 1 wherein the solution of the salt is an aqueous solution of aluminum acetate.

3. The process of claim 1 wherein the solution of the salt is an aqueous solution of zirconium nitrate.

4. The process of claim 1 wherein the perfiuorodecanoic acid is dissolved in a highly polar organic solvent.

5. The process of claim 4 wherein the organic solvent is ethanol.

6. The process for producing a fabric resistant to soil, grease, oil, and water-borne stains which comprises immersing the fabric in an aqueous solution of aluminum acetate, drying the fabric, and then immersing the fabric in a solution containing sodium acetate and perfiuorodecanoic acid to produce on the fibers of said fabric an active substrate having attracted thereto the carboxyl end of the molecule of said perfiuorodecanoic acid, thereby providing a highly oriented surface of -CF;, groups which is both hydrophobic and oleophobic.

7. The process for producing a fabric resistant to soil, grease, oil, and water-borne stains which comprises immersing the fabric in an aqueous solution of zirconium nitrate, neutralizing the fabric in a dilute aqueous alkaline solution, and treating the neutralized fabric with a solution of perfluorodecanoic acid to produce on the fibers of said-fabric an active substrate having attracted thereto the carboxyl end of the molecule of said perfiuorodecanoic acid, thereby providing a highly oriented surface of CF groups which is both hydrophobic and oleophobic.

8. The process for producing a fabric resistant to soil, grease, oil, and water-borne stains which comprises immersing the fabric in an aqueous solution of zirconium nitrate, partially drying the fabric, neutralizing the partially dried fabric with a dilute aqueous alkaline solution, drying the neutralized fabric and then immersing the fabtie in a solution of perfiuorodecanoic acid to produce on the fibers of said fabric an active substrate having attracted thereto the carboxyl end of the molecule of said perfiuorodecanoic acid, thereby providing a highly oriented surface of CF groups which is both hydrophobic and oleophobic.

9. The process of claim 8 wherein the dilute aqueous alkaline solution is a solution of ammonium hydroxide.

10. The process for producing a fabric resistant to soil, grease, oil, and water-borne stains which comprises immersing the fabric in a solution of a salt selected from the group consisting of aluminum acetate, zirconium nitrate, and zirconium butoxide, drying the fabric and immersing the dried fabric in a solution of perfluorooctanoic acid to produce on the fibers of said fabric an active substrate having attracted thereto the carboxyl end of the molecule of said perfiuoro-octanoic acid, thereby providing a highly oriented surface of --CF;, groups which is both hydrophobic and oleophobic.

11. The process of claim 10 wherein the solution of the salt is an aqueous solution of aluminum acetate.

12. The process of claim 10 wherein the solution of the salt is an isopropanol solution of zirconium butoxide.

13. A soil, grease, oil, and water-stain resistant fabric having the surface of the fibers thereof coated with an active substrate comprising a salt selected from the group consisting of aluminum acetate, zirconium nitrate, and zirconium butoxide and a coating on said salt of a compound selected from the group consisting of perfluorooctanoic acid, perfluorodecanoic acid, and salts thereof wherein the carboxyl ends of the molecules of said compound are attracted to said active substrate, thereby providing a highly oriented surface of -CF groups which is both hydrophobic and oleophobic.

14. The fabric of claim 13 wherein aluminum acetate is coated with perfluoro-octanoic acid.

15. The fabric of claim 13 wherein aluminum acetate is coated with perfluorodecanoic acid.

16. The fabric of claim 13 wherein zirconium nitrate is coated with perfluorodecanoic acid.

17. The fabric of claim 13 wherein zirconium butoxide is coated withe perfluoro-ootanoic acid.

18. A process for producing a fabric resistant to soil, grease, oil, and water-borne stains which comprises immersing a fabric ina solution of a salt selected from the group consisting of aluminum acetate, zirconium nitrate, and zirconium butoxide, drying the fabric, and immersing the fabric in a solution of perfluoromonocarboxyl compound selected from the group consisting of perfluoroootanoic acid, perfluonodecahoic acid, and salts thereof to produce on the fibers of said fibric an active substrate having attracted thereto the carboxyl end of said perfiuoromonocarboxyl compound, thereby providing a high 1y oriented surface of -CF;; groups which is both hydrophobic and oleophobic.

References Cited in the file of this patent UNITED STATES PATENTS Schroeder Nov. 3, Doser Feb. 27, Schwartz Mar. 25, Edelstein July 6, Diesslin et a1. Sept. 4, Figdor Apr. 14, Reid Dec. 15,

FOREIGN PATENTS Great Britain Apr. 18,

Claims (1)

1. THE PROCESS FOR PRODUCING A FABRIC RESISTANT TO SOIL, GREASE OIL, AND WATER-BORNE STAINS WHICH COMPRISES IMMERSING THE FABRIC IN A SOLUTION OF A SALT SELECTED FROM THE GROUP CONSISTING OF ALUMINUM ACETATE, ZIRCONIUM NITRATE AND ZIRCONIUM BUTOXIDE, DRYING THE FABRIC, AND IMMERSING THE DRIED FABRIC IN A SOLUTION OF PERFLUORODECANOIC ACID TO PRODUCE ON THE FIBERS OF SAID FABRIC AN ACTIVE SUBSTRATE HAVING ATTRACTED THERETO THE CARBOXYL END OF THE MOLECULE OF SAID PERFLUORODECANOIC ACID, THEREBY PROVIDING A HIGHLY ORIENTED SURFACE OF -CF3 GROUPS WHICH IS BOTH HYDROPHOBIC AND OLEOPHOBIC.

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