Zirconium Compounds in VaterRepellents for Fabrics w.'. B. BLUMENTHAL Sational Lead Company, Niagara Falls,
T
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iV. Y .
application of T h e development of water-repellent treatments for were obtained by impregfabrics, based on the use of zirconium salts, is reviewed nating textiles with metal zirconium chemicals to briefly, and some limitations of the salts are noted. Exhydroxides, drying, and the improvement of textiles perimental work is reported in which i t is shown that then superposing a coathas attracted attention for zirconium salts used alone render textiles somewhat a t least half a century. Ining of wax, as by immerswater repellent, and when used i n conjunction with soaps ing in a solution of paraffin vestigators have reported and wax emulsion, a very high quality of water-repellence wax in carbon tetrachloride their effects in dyeing ( 1 , results. Tater repellence so imparted is generally lost 14, 18), silk weighting ( 7 , (6). 3Iuller noted that 12, 15), white pigmenting tj? laundering or dry cleaning the fabric but may be zirconyl acetate servei: as stabilized to some extent by treatment with an additional (I?), and flameproofing an emulsifier of waxes and solution of a metal salt having a strongly acid hydrolysis. (16). The most extensive fatty materials and pre.1 mechanism for the repellence of water by the treated and successful application pared water-repellent baths has been to water repelfahric is propounded. from which other emulsifylence. The rudiments of ing agents were eliminated (IO,12). this technology were described by White (19),who outlined a number oi methods for the All the foregoing processes specified the use of zirconium salts water-repellent treatment of textiles a ith raie eaith salts, which exhibit acid reactions in water. Von Mater (8, 9) developed a method of treating fabrics in a bath containing a soluble among which he included zirconium saltb. TThite treated fabrics double carbonate of alkaline reaction, such as ZrOCOa. (NH4)*x-ith either: CO, plus a soluble soap. He found that after a fabric had been 1. A solution of a iaie raith soap in an organic solvent, such dipped into such a bath and then dried, insoluble zirconium soap as gasoline or turpentine was left on the fibers and the fabric m-as water repellent. 2. An aqueous alkali soap solution, followed by a solution of The theory of viater repellence has been studied in great detail a rare earth salt and a useful summary of such studies i j presented in a report by 3. d n aqueous fatty acid eniulsion (which might also contain other emulsified matter, such as rubbei 01 v axea), followed by a Rowen and Gaglia.rdi ( I S ) . This report shows the water repelsolution of a rare earth salt lence of a fabric to depend both on physical condit'ions-such as 4. An aqueous solution of x raie eaith salt, then an alkaline fiber radii, distances betlveen fibers, roughness of the surface, and solution to form the hydroxide, carbonate, or phosphate of the surface porosity-and on the adhesive forces between the surface rare earth in the fiber, then an allcalinr soap solution and water. It is the last of these factors xhich is altered by a The water repellence depended essentially on the impregnation water-repellent t'reatment. The angle of contact between the periphery of a droplet of of the fabric with an insoluble metal soap. The use of the rare water and a surface on which it lies is a measure of the adhesive metals was asserted to be more satisfactory than the earlier use forces between the water and the surface. Figure I represents a of aluminum because aluminum compounds tend t o dissolve in droplet of water lying on a solid surface and making the angle of alkaline water (such as soap solutions used in laundering) with contact,, 8. formation of aluminates, whereas the rare earth compounds do not, Therefore, they generally endure more satisfactorily on When R is 90" or more, wat,er repellence is generexposuie to a ater. Oxides and similar gelatinous compounds of ally high, and when e is rare earth metals impart a certain amount of water repellence to considerably below 90O it fabrics, even in the absence of soap radicals (20). is relatively slight. This Doser, Bayer, and Hintzmann ( 2 ) found it advantageous to is explained by the diareplace the fatty acid by an aIomatic o-hydroxy carboxylic acid grams in Figure 2 which containing a substituent which imparts hydrophobic qualities represent idealized crossto the molecule. For example, a fabric is soaked briefly in an sectional views of fabrics, aqueous solution of stearyl-p-aniinosalicylic acid, then washed Figure 1. The Contact Angle, a t high magnification, I n and dried. I t is then found to be water repellent and retains its 0, between Water Drop and ~i~~~~2-4 the position of water repellence, according t o those authors, even when boiled Solid Surface the droplet of water which in a soap solution containing 3 grams per liter of soda in addition makes a large contact to the soap. These same investigators later patented a process angle Kith the fibers is shoim, and the equilibrium position of the ( 3 ) for rendering textiles water repellent by immersing them in a lower boundary is above the cloth, as represented by lines A d . zirconium acetate solution containing emulsified wax and variWhen the water makes a l o v contact angle with the fibers, thc ants thereon. The zirconium compound \vas thought t o fiu the boundary stands below the cloth, as represented by line RB, penewax to the textile and a high degree of water repellence was tration has occurred, and the fabric is not water repellent (IS). thereby attained. I n a later patent specification these investigaIt is also obvious that when the force of adhesion is low (high tors stated that certain advantages resulted from the use of some contact angle), droplets of n-ater will readily be shed by the fatty acid in the bath, and the leaching of the treated fabric with cloth when its surface is not horizontal, and the droplet can easily hot water or alkaline solution t o remove hydrophilic substances ( 4 ) . be brushed off. Edelstein found that water-repellent finishes of good durability
640
INDUSTRIAL AND ENGINEERING CHEMISTRY
April 1950
The water-repellent formulas developed by the investigators cited have not proved entirely satisfactory for general industrial use. Some of the proposed organic agents were too expensive; those procedures requiring a series of dippings with drying in between were time-consuming and uneconomical; and the water repellence has always been found to deteriorate rapidly when the fabric was laundered or dry cleaned (IS). I n recent years the problem of preparing a more satisfactory mrater-repellent treatment has engaged the attention of many laboratories, and numerous preparations have been offered on the market for the water-repellent treatment of textiles. Studies were undertaken by the author t o (1) evaluate the quality of water repellence obtained with certain zirconium compounds, (2) improve the utility of these compounds by developing new formulations which are easy to apply and which coat the fabric with films that are both highly water repellent and durable, and (3) t o investigate the mechanism whereby the zirconium agents produce their typical water-repellent effects.
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A
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Figure 2. Representations of Cross-Sectional Views of Equilibrium Positions of Drops of Water on Repellent ( l e f t ) and Nonrepellent ( r i g h t ) Fibers
I n the work reported here, quality of water repellence was evaluated by the "spray test" ( 6 ) , and laundering resistance was evaluated by subjecting the treated textile to a series of standardized hand launderings, using Ivory soap as the detergent, and determining the spray rating after each laundering. All launderings were performed by the same worker. The 8-inch squares of test cloth were soaped once, then rinsed thoroughly in a large excess of water. The number of launderings which the fabric sustained, before its spray rating fell below 70, was taken as the measure of laundering resistance, Resistance to dry cleaning was evaluated similarly by repeatedly stirring the fabric for 5 minutes in commercial ethylene dichloride, wringing and drying, and determining the spray rating I n this case, likewise, the number of leachings which the fabric sustained before its spray rating fell below 70 was taken as a measure of dry-cleaning resistance. WATER-REPELLENT PROPERTIES OF ZIRCONIUM SALTS
A series of solutions was prepared containing approximately 1 gram of zirconium oxide (ZrOz), in various saline formulas, per 100 ml. of the solution. Eight-inch squares of Indianhead cotton cloth were immersed for 1 minute, each in one of the solutions or baths, then wrung out and dried at 107" C. Table I shows the spray ratings of the respective cloths. All the zirconium salts exert a water-repellent effect, generally preventing the penetration of water through the cloth but not preventing wetting of the exposed surface, The addition of a suitable emulsified wax prevented entirely the wetting of the cloth surface. I n view of the excellent water repellence obtained with Ceremul A, six wax emulsions supplied by the Socony-Vacuum Oil Company were compared, with the results shown in Table 11. All except one were beneficial, but the Ceremul A was best. Experimentation with the proportions of ammonium ziroonyl dicarbonate, ammonium oleate, and Ceremul A showed that best results were obtained using the zirconium salt at the concentration of 1.0 gram of zirconium oxide per 100 ml. and using 1 mole of fatty acid t o 2 of zirconia and 1 gram of wax t o 1 gram of zirconia. (Other organic acids were used satisfactorily in place
641
TABLEI. WATER-REPELLENT EFFECTS OF ZIRCONIUN SALTS, WITH AND WITHOUT
OTHERAGENTS
Contents of Solution Used for Treating Cloth Animoniuni zirconyl dicarbonate [ 1 SHd2ZrO;CO:,?] .-immoniuin zircon1.l dicarbonate T am:noniuin oleateb .\m?nonium zirconyl ;livar&nate f a!nmoniuin oleate -7. wax emulsionc (Ceremul A) Ceremul A alone Zirconium ietraacetate [Zr CzHsOz)4] Zirconvlacetate IZrO(CzHabdz1 Zirsonyl acetate-+ wax emulsionc (Ceremul A) Zirconyl chloride (ZrOClz)
Spray Rating" of Treated Cloth 30.50 60
100 50 60 40 100
50d
sion. d The cloth was severely attacked by the treatment.
of oleic acid-for example, stearic, naphthenic, linoleic, corn oil, acetic, and oxalic.) Subsequently, it was found that the more stable ammonium zirconyl tricarbonate, (NH&HZrO(CO&, could be used in place of the dicarbonate, and the above formulation with the tricarbonate was used in obtaining results described hereafter. This bath is referred t o as bath 1. Gabardine and rayon cloths were treated, by the method described, using bath l, and showed a spray rating of 70. Other samples of the same cloth were laundered with Ivory soap and water and dried, before submitting to the treatment. The latter samples of the cloth showed spray ratings of 95. I n view of these results, all cloth specimens were laundered before using in experiments with water-repellent baths. Applying bath 1 to a series of different fabrics, M-ater-repellent effects were obtained as shown by Table 111. Although most textiles are rendered water repellent (spray rating of 70 or higher), the quality varied considerably, even for different grades of fabric of the same fiber. DURABILITY OF WATER-REPELLENT FINISHES
The tendency of fabrics which have received water-repellent treatment to lose their water repellence on laundering or dry cleaning has been discussed above. The writer found that a fabric treated by the process described, using bath 1, lost its
TABLE11. RELATIVEWATER REPELLENTVALUE OF PROPRIETARY WAXEMTTLSIONS Wax Emulsion Used in Spray Rating of Treating Solutiona Treated Cloth Ceremul A 100 Ceremul C 95 Ceremul P 50 Ceremul Q 80 Ceremul R 80 PD-351 G 90 * The bath contained per 100 ml.: 1.0 gram of ZrOz as (NHa)zZrO(COa)z; 1.16 grams of oleic acid as ammonium oleate; and 2 . 5 grams of wax emulsion.
TABLE111. SPRAYRATINGSSHOWNBY DIFFERENTTEXTILES TREATED WITH BATH1 Textile Cotton Broadoloth Indimhead Gabardine twill Unspecified grade Khaki Linen iMuslin Nylon Rayon Crepe Faille Shantung Spun Silk, pure Wool flannel
Spray Rating 65 100 95 25,50 85 100 75 50 95 100 95 85 95,100 100 100
INDUSTRIAL AND ENGINEERING CHEMISTRY
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water repellence after one or two launderings or one extraction with ethylene dichloride. Simple alterations in the process, such as changing the composition of the bath or using temperatures other than room temperature, had negligible effects on the durability of the treatment. An effective method of improving the resistance of the waterrepellence of the fabric to both laundering and dry cleaning was found to consist in the use of a second bath. The fabric was immersed in bath 1 and wrung out; then, it was immersed in the second bath for 2 minutes; and, finallv, it was rinsed in fresh water, wrung out, and dried. Table I V shows the effect on laundering resistance when various salts were used as solutes in the second bath, hereinafter designated as bath 2. Those salts which hydrolyze most strongly t o yield acidic solutions appear most effective in stabilizing the water repellence against laundering. It was found, however, that a hydrochloric acid solution of the same p H as an effective stannous chloride solution was of no value in enhancing laundering resistance. The enormous difference between the effects of barium chloride and stannous chloride shows that the anion, as such, plays no significant role in the beneficial effects of bath 2. The twobath treatments, like the previous one-bath treatments, had practically no effect on the fabrics other than rendering them water repellent. Unfortunately, it was found that the laundering resistance effected by use of solutions of stannous chloride and basic zirconyl chloride (ZrJOsCl?) was not readily reproducible, and the resistance to laundering of fabrics treated with both baths (1 and 2) was apt to vary over a range of two to eight Iaunderings. To prevent these vagaries, rigorous controls over procedure JTere introduced-that is, the cloth was carefully conditioned by prelaundering and drying in controlled atmospheres, and the temperatures of the baths, immersion times, and details of handling were scrupulously standardized. It was found that consistent results could be obtained on a series of treatments of fabrics, all run on the same day, but there was an uncontrolled displacement of values in series run on different days. Indianhead cotton cloth treated with baths 1 and 2 (Zr,O,Cl,) was found to retain its water repellence through 5 leachings with ethylene dichloride, whereas without bath 2 it would not withstand a single leaching. Attempts to combine baths 1 and 2 into a single bath were unsuccessful Although bath 2 was consistently effective when used in conjunction Kith bath 1, it was not effective when used after other water-repellent baths-namely zirconyl acetate or aluminum formate. MECHANISM O F WATER-REPELLENT EFFECTS OBTAINED WITH BATH 1
Smears on glass were made of aqueous solutions or emulsions of the following, a t the same concentrations used in bath 1: (a) Ceremul A; ( b ) ammonium zirconyl tricarbonate plus ammonium oleate; and (c) a niixtule of a and b. The smears were dried at 90’ C. Drops of water were placed on the dried smears, and the approximate angles of contact mere estimated visually. The following results were observed: Constituents of Surface Treatment on Glass None Ceremul A Ammonium zirconyl carbonate f ammonium oleate Ammonium zirconyl carbonate ammonium oleate Ceremul A
+
+
Angle of Contact Very small Considerably < 90° Kearly 92O,” About 90
Thus, the untreated glass surface was hydrophylic, whereas the films formed by the agents listed were hydrophobic. I t is to be expected that the deposition of such films on fibers would render them water repellent according t o the mechanism reviewed by Rowen and Gagliardi ( I S ) . It has already been observed that Ceremul A alone has only a small water-repellent effect on the fabric (Table I). It must be inferred, therefore, that the wax does not adhere t o the fabric
Vol. 42, No. 4
TABLE IT. E F F E C T S O F V A R I O U S S.4LTS AS S O I J l T E S I N BATH2 o s SPRAYRATINGAND LAUNDERING RESISTANCE OF TREATED INDIANHEAD COTTON CLOTH No. Laundorings Salt Used in Initial Spray Sustained without Decrease Bath 2a Rating in Spray Rating t o Below 70 AICls 85 7 50 BaClz 0 CaClz 50 0 CusOr 80 b FeCL 100 5 FesOa 95 2 h?gCIz 50 0 XnCh 75h 5 SaCl 95 0 xis04 85 1 No salt inn 0 Pb(S0s)n 75 0 SnClz 100 8s. ZrOClz in0 8 ZrO(CzHs0z)z 100 2 ZrzOsC12 95 8 a Baths contained 3 grams of dissolved hydrated salt per 100 ml. On successive launderings, spray ratings rose, then fell.
and the zirconium of bath 1 serves the function of k i n g the wax a t the surface of the fibers. CONCLUSIONS
When many textiles are immersed in aqueous solutions of zirconium salts, they absorb a layer of zirconium coinpound a t the fiber surlaces. This layer imparts sufficient water repellence to the fabric t o prevent, partially or completely, penetration of water spray through the dried textile. If certain suitable wax emulsions are used with the zirconium salt, some of the way is held by the zirconium in the surface layer and improves the water repellence t o the extent of rendering the dried fabric also resistant to surface vietting. The waxy material is easily washed out of the film laundering or dry cleaning, leading to loss of resistance t o surface wetting. B y superposing an additional layer of an inorganic substance, such as tin or zirconyl cations, a certain amount of protection is afforded t o the w , x particles, and they are less readily removed by the action of soap and water or of organic solvents. ACKNOWLEDGRIENT
The author acknowledges his indebtedness to S. F. Urban, for many useful suggestions which materially assisted the progress of the investigation reported herein, and t o R. Seifert for valuable assistance in the laboratory procedures. LITERATURE CITED
Barnes, J. J., SOC.Chem. Ind., 15, 420 (1896). Doser, Bayer, and Hintzmann, U. S. Patent 2,191,982 (Feb. 27, 1940). Ibid., 2,316,057 (dpril 6, 1943). Ibid., 2,328,431 (Aug. 31, 1943). Edelstein, O., Ibid., 2,323,387 (July 6, 1943). Federal Standard Stock Catalog, see. IV. Part 5, CCC-T-19la (Suppl. Federal Spec. for Textiles, general instructions, test methods) (Oct. 8, 1945). Landau 8: Co. and Kreidl, I., German Patent 258,638 (1913). Mater, H. von, U. S. Patent 2,402,857 (June 25, 1946). Ibid., 2,457,853 (Jan. 4, 1949). Maller, A, Ibid., 2,345,142 (March 28, 1944). I b i d . , 2,350,800 (June 6, 1944). Ristenpart, E., Farben-Ztg., 29, 26 (1918). Rowen, J. W., and Gagliardi, D., J . Research iL‘atZ. Bur. Standards, 38, No. 1, 103-17 (1947). Scheuer, A., and Bryliuski, Bull. SOC.MuZhouse, 68, 124 (1898). Stern, E., German Patent 261,142 (1913). Venable, F. P., “Zirconium and Its Compounds,” New York, Chemical Catalog Co., 1922. Weiss, L., German Patent 235,495 (June 10, 1911). Wengraf, P., Farben-Ztg., 25, 277 (1914). White, C. B., U. S. Patent 1,536,254 (May 5 , 1925). Ibid., 1,717,483(June 18, 1929). RECEIVED August 4, 1949.
