US3068125A - Treatment of textile materials for repellency to chemical warfare liquids - Google Patents

Description

United States Patent Ofiice 3,%8,l25. Patented Dec. 11, 1962 3,068,125 TREATMENT OF TEXTHLE MATERIALS FQR RE PELLENCY T CHEMECAL WARFARE LIQUKDS Robert L. Ciayton, lira, New Urleans, La, and Leopold Loch, Louisville, Ky, assignors to the United States oi America as represented by the Secretary of the Army N0 Drawing. Filed June 24, 1957, Ser. No. 667,713 in Claims. (Cl. 117-161) (Granted under Titie 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This invention relates to a process for impregnating textile materials which renders said materials resistant to penetration or wetting by liquid droplets of chemical warfare agents. This invention relates particularly to the single application treatment of such textile materials with a composite preparation comprising as its essential ingredients, a chromi-nuclear complex of a fluorinated monocarboxylic acid and a water-insoluble vinyl-type polymer.

Pending patent applications Serial Nos. 667,717 and 667,719, filed on the same day as this application, describe surface coatings resistant to chemical Warfare liquids and the procedures for applying such resistant finishes to textile fabrics. The present invention differs significantly from those described in the pending applications above. This difference and the attendant advantages arise from the incorporation of the active ingredients in one composite mixture. The present invention allows for greater simplicity of application of the repellent coating together with such non-obvious advantages as improved repellency and greatly improved stability of the chrorni-nuclear complex in the impregnating composite.

The newer chemical warfare liquids, particularly those designated as the G-agents, penetrate and wet through untreated porous textile fabrics substantially instantaneously regardless of the chemical composition, construction or Weave of the cloth. Numerous compositions and treatments for coating textiie materials have been developed to render such materials impermeable to water and similar polar liquids. Such treatments are, in gen oral, or no value in proofing textile materials against chemical warfare liquid agents of the type mentioned above. The G-series agents are polar liquids of low SUI? face tension and are good solvents for many other organic materials.

By the term G-agents or G-series agents we refer to those compounds designated by the Chemical Corps, United States Army, as GB (isopropyl methylphosphonofluoridate), GF (cyclohexyl methylphosphonofluoridate), and GA (ethyl dimethylphosphoroamido cyanidate).

According to the procedures described in the present invention, textile fabrics may be rendered nearly impermeable to the passage of liquid droplets of chemical warfare agents while at the same time the textile after treatments according to these procedures, exhibits air and water-vapor permeability greater than that of the orginal fabric.

A primary objective of this invention is to provide a simple, single application process for the treatment of textile fabrics which will resist penetration and wetting by the highly active chemical warfare agents and in particular will be resistant to the agent designated as stabilized GB for at least 1-2 hours, and which produces a fabric having such textile properties as air permeability, softness, and tear resistance substantially as desirable as the untreated fabric. Another object is to provide a repellency treatment and impregnation techniques of such simplicity that they may be practiced as a bucket-type impregnation for use in the field without the employment of any control or usual textile processing apparatus, and requiring no cure at elevated temperatures after impregnation. Another obiect is to provide a procedure for producing a stable, free-flowing, iiuid composite mixture of a chromi-nuclear complex, in which the acido group consists essentially of a perfluoroalkanoyl or w-mono hydrofiuoroallranoyl group containing 4 to 18 carbon atoms, and a Water-insoluble vinyl-type polymeric material. Still another object is to provide a process for bonding Werner-type chromi-nuclear complexes of perfluoroor monohydrofiuoro-monocarboxyiic acids to acid sensitive materials, without causing undue degradation induced by the acid.

In general, in accordance with the present invention, a textile material is rendered resistant to penetration or wetting by liquid chemical Warfare agents by: impregnating the textile in an aqueous dispersion containing in admixture l240% of a water-insoluble resin of the vinylpolymer type and 0.6 to 3.0% of a chromi-nuclear complex, the acido group of which is either a perfluoroalkanoyl or a monohydrofiuoroalkanoyl group to a dry pick-up of from about 25-70 percent by weight. In order to prevent coagulation on addition of the highly acid :chromi-nuclear complex, it is necessary that the vinylpolymer type emulsion possess considerable acid tolerance. Good stability of the composite emulsion has been obtained only with non-ionic, electrically neutral emulsifiers, such as alkylphenyl polyethyleneglycol ethers, polyethyleneglycol alkyl ethers, alkyl aryl polyester alcohols, and polyoxyethylene lauryl alcohol. Suitable polymers in the form of non-ionic aqueous emulsions, are included in the group consisting of polymers derived from lower alkylesters of acrylic acid and esters of vinyl alcohol with the lower carboxylic acids. Although stable composite emulsions may be prepared with chromi-nuclear complexes having acido groups containing two or more carbon atoms in the fluoroalkanoyl group, only those complexes in which the acido group consists of fluoroalkanoyl groups containing at least 4 carbon atoms give the desired repellency. Curing of the impregnated fabric may be accomplished immediately at temperatures from about to C. for from about 30 to 90 minutes or preferably the wet impregnated fabric may be cured as above after first allowing to air-dry at temperatures from 20- 40 C. Significant, though in some cases slightly reduced, repellency may be obtained by merely air drying at temperatures from about 2040 C. without curing at an elevated temperature.

Substantially any textile material composed of vegetable, animal, synthetic, or glass fibers may be employed. The employment of fabrics composed essentially of cellulose textile fibers is preferred. The invention is especially adapted for the treatment of cotton clothing fabrics such as cotton sateen and the like.

The polymer dispersion can contain the amounts and types of emulsifying, wetting, and/or dispersing agents Darexes.

aces,

that are usually employed in polymer compositions adapted for production of surface coatings with the restriction that any such additives should not be so sensitive to acid as to cause coagulation, precipitation, or separation of the emulsion on addition of the chromi-nuclear complex. The polymeric constituent of the treating composite can vary widely in molecular weight or degree of polymerization. Illustrative examples which are commercially available include film-forming dispersions of polyalkyl acrylates and polyvinyl acetates which are available under the trade names Rhoplexes, Polycos, and Dispersions of polyethyl acrylate prepared by emulsion polymerization with a non-ionic emulsifier have also proved satisfactory.

The Werner-type chromi-nuclear complexes in which the acido group consists essentially of perfiuoroalltanoyl groups are known compounds. Processes of producing them are described in US. Patent No. 2,662,835, and British Patent No. 712,784. These complexes are the perfiuoroalkanoyl analogs of the complexes described in US. Patent Nos. 2,373,040 and 2,544,666. They can be produced and applied by procedures described in the patents cited above. In general, the perfiuoroalkanoyl chromi-nuclear complexes can be prepared by effecting contact in solution between the perfiuoroalkanoic acid and a basic trivalent chromium salt of a monobasic acid, which salt has a basicity less than 50%. The complexes can be dissolved in organic solvents such as isopropanol and the like alcohols. Illustrative examples of acids suitable for employment as the acido group in the complexes include: perfiuorohexanoic, perfluoro-octanoic, perfluorodecanoic and the like acids, as well as w-monohydrofiuoroalkanoic acids of the type H(CF ),,COOH, in Which the hydrogen atom is on the terminal carbon atom and n has even integral values between 4 and 18, inclusive. The complexes in which the acido groups consists essentially of perfiuoroalkanoyl groups containing 8-10 carbon atoms is preferred.

In preparing the composite emulsion for impregnating the textile material, the chromi-nuclear complex, usually prepared or obtained as a 30-40% solution in isopropanol, is partially diluted with water to give an aqueous solution containing from about 1 to percent by weight of the solid complex. The aqueous solution of the chrominuclear complex is added slowly and with good stirring to the aqueous dispersion of the vinyl type polymer containing 12 to 60% of the polymer solids.

impregnation of the textile material may be accomplished substantially immediately after mixing of the composite emulsion or preferzbly the composite emulsion may be aged for several days prior to employment as a repellency treatment for the textile material.

We have found that the repellency imparted to the textile material is greatly enhanced by the aging process, and it is postulated that during this aging process there is a progressive adsorption of the chromi-nuclear complex molecules onto the surface of the dispersed polymer particles and that this adsorption occurs in such manner that the polar end of the complex molecules containing the chromium atoms are affixed to the surface of the polymer particles with the perfiuoroallranoyl groups extending outward from each polymer particle to form an outer layer consisting essentially of chains of carbon atoms surrounded by fluorine atoms. While the practice of this invention is not premised upon any particular theory or postulated mechanism, it has been definitely shown that the repellency imparted to the fabric is greatly improved if the composite emulsion is allowed to age for 3 to 5 days prior to impregnation and that this improvement applies particularly to the repellency obtained on the fabric not cured at an elevated temperature. It has further been found that this aging process can be accelerated by mild heating of the composite emulsion at temperatures from about 40 to 80 C. for periods of time from about 5 to 4 180 minutes, or by preheating the diluted aqueous solution of the chromi-nuclear complex prior to admixture with the polymeric resin.

The textile material can be impregnated with the composite emulsion by means of the usual procedures and apparatus for liquid impregnation of textile materials, employing padders, centrifuges, squeeze rolls, and the like. In the field the impregnation can be accomplished by a simple hand dipping and squeezing employing a dispersion concentration and squeezing procedure found by experiment to produce the proper pick-up. The impregnation of the textile fabric to a dry pick-up of from about 25-50 percent by weight is preferred.

The following examples are illustrative of the details of at least one method of practicing this invention; although testing is reported only with liquid GB, the successful repellency treatments for GB have been found as shown, for example, by the applications identified earlier in this application, so outstandingly successful for the other chemical warfare agents, such as GA, HD, (2,2'dichlorodiethyl sulfide) and HN-3(2,2,2" trichlorotriethylamine) that further testing with those agents is not required.

As used in this specification, the terms wetting time" and penetration time have the following meanings. Wetting time is the time required for a drop of liquid, placed on the upper side of the fabric, to dissipate, i.e. to completely lose its identity as a drop. Penetration time is the time required for the underside of the fabric to show the first trace of penetration by a drop of liquid placed on its upper side.

Example I I Repelleney to dro lots or Weight Weight Stabilized (i 13 Emulslon No. ercent percent C404 Rhoplex FRN Penetration Wetting me time (1 second) (30 seconds) Both resistance to penetration and wetting through increase very markedly with increasing resin concentration In the treating composite and also with increasing concentration of the chromi-nuclear complex, although the improvement with the latter is less notable.

Example 2 Swatches of 8.5 oz. cotton sateen were impregnated in composite emulsions containing 32 weight percent of the commercially available polyacrylic ester emulsion (Rhoplex FRN) and varying amounts of the chrominuclear complex of perfiuoro-octauoic acid (PC-804),

The composition data for these emulsions and the impregnation data are summarized in the table below:

. FC-804 Rhoplex Dry Emulsion No. solids, FRN Swatch pick-up, percent solids, No. percent percent 0. A 44.6 1 6 {B 41.4 2 1.5 A 47.3 32.0 {E2 2 All of these swatches were cured for one hour at 110 C. and then tested with stabilized liquid 63.

Repcllency to Stabilized GB Porosity Tenderization Emulsion Swatch No. No.

Penetra- Wetting t-ion time, time seconds seconds 6, 3 0 14,000 in an 88 }Fair Slight.

9, 00 27,0 11,000 14,000 }Poor Greatest.

In consideration of both repellency and physical properties of the treated sateen, a composite emulsion corresponding to the composition of Emulsion #1 above is a preferred treatment for cotton sateen.

In order to demonstrate the beneficial effect of aging of the composite emulsions and to demonstrate the high stability of chromi-nuclear complex, Emulsion #1 above was stored at room temperature for a period of 18 days and used at various intervals during this time to treat swatches of cotton sateen.

It is apparent that incorporation of the chromi-nuclear complex in the non-ionic emulsion imparts a much higher order of stability to the complex than is possible in aqueous solutions of the complex.

As a further example of the beneficial eiiects of aging of the composite emulsion on repellency, samples of 8.5 02. cotton sateen were treated on consecutive days in an impregnation composite containing 0.6% of the commercially available chromi-nuclear complex, FC-804, and 32% of the commercially available polyacrylic ester emulsion, Rhoplex FRN. After impregnation the sateen swatches were either immediately cured at 110 C. for one hour or simply allowed to air dry at room tempera ture. The repellency of these treated samples of cotton sateen to stabilized GB is tabulated below:

Swatches oven cured Samples air dried after after impregnation impregnation Age of composite emulsion, days Penetration Wetting Penetration Wetting time, time, time, time, seconds seconds seconds seconds (1 day) 5 12, 000 218, 000 9, 000 19, 000

(6 days) 6 10, 000 432, 000 6, 000 20,000

(5 days) 11 10, 000 518, 000 4, 000 23,000

(6 days) 18 7, 000 513, 000 7, 000 10,000

(6 days) As an example of the beneficial effect of mild heating on the repellency obtained in treatments with the composite emulsion, an emulsion identical to that described immediately above was prepared. Portions of this composite emulsion were heated at 40 C. for periods up to 1 hour after mixing and then used for the treatment of swatches of cotton sateen. All swatches were cured for one hour at C. and then tested with stabilized GB as indicated in table below:

Repellency to stabilized GB Time 0! Swatch No. heating at 40 C Penetration minutes time, Wetting time seconds 0 2,000 24,000 seconds. 10 5.000 30 hours. 30 5,000 24 hours. 60 5,000 24 hours.

1 Control.

It is seen that the beneficial effect previously noted on aging of the composite emulsion may be greatly accelerated by mild heating for brief periods prior to impregnation of the textile material.

Example 3 A 10 x 60-inch strip of cotton sateen was impregnated in a composite emulsion identical to the last emulsion described in Example 2 (0.6% FC-804, 32% Rhoplex FRN). The composite emulsion had aged six days at the time of impregnation of this strip. The strip was padded after impregnation so as to give a dry-pick-up of 51 percent by weight. After padding, the strip Was allowed to air dry and was then cured at 110 C. for one hour. The repellency of this strip of treated sateen to stabilized GB was very high; penetration time varied from 7,000 to 27,000 seconds, and wetting time was in excess of 5 days. The physical properties of this strip of treated sateen are tabulated below:

Air permeability is approximately doubled while abrasion resistance is increased about 50-fold.

Example 4 Samples of 8.5 oz. cotton sateen were impregnated with composite emulsions containing the commercially available chromi-nuclear complex of perfluoro-octanoic (FC- 8 804) and the below indicated polymeric materials, some stituent of the composite emulsion is a non-ionic acrylic of which are available under the indicated trade names, ester polymer emulsion. and then cured for one hour at 110 C. 3. The process of claim 1 in which the polymeric con Repelleucy to stab. GE Polymer FC-SO! Dry- Commercial name Polymer type solids, solids, pickup, percent percent percent Penetra- Wetting tion time, time,

seconds seconds Polyco 505 Polyvinyl acetate 44 0.0 97 20,000 21,000 5, 000 15. 000 Rhoplex WN-75 do 44 0. 6 7s 20, 000 21, 000 4 5,000 0.000 Dare: XssL- do 44 0. 6 68 10,000 15, 000 (Lab. prep.) Polyethylacrylate 12.3 0.6 18 1, 500 9,000

l Emulslfied with a polyethylene glycol alkyl ether.

Example 5 stituent of the composite emulsion is a non-ionic, vinyi Chromi-nuclear complexes were prepared according to acetate polymer cmulslop' Example 1 of US. Patent 2,544,666 in which the acido 20 The process of cialm 1 the lljlolymenc 6011' group consisted essentially of perfluorobutyric acid and i of the composmaf emuislon polyet aciylate' perfiuorodecanoic acid. These two chromi-nuclear comhe.process of m w i c rpml'liuclear plexes were isolated at 30-35% solutions in isopropanol. ig mccrporaied m t 6 2 3? 15 m Whlch Sutficient of each chromi-nuclear concentrate was taken ig i consists 655mm y 0 per uoro'octanoy to give composite emulsions with Rhoplex FRN containb ing 0.6% by weight of the chromi-nuclear complex and Tnepmcess of i 1 m whlqh chroml'nuclear 32% by Weight of the acrylic polymer. The composite coinp nwrporafed m h einulsion 1S a product the emulsions of these two Chmmimudear complexes were acido group of which consists essentially of perfluorodecused immediately to impregnate swatches of cotton sateen. anoyl groups These swatches, after curing for one hour at 100 G, ex- Theprocess of C 3 1 m which chroml'nuclear hibited repellency to stabilized GB as indicated in the coinplsx mcorporatid m emulslori 1s a product the table below: acido group of which consists essentially of perfluorobutyryl groups.

8. A composition for bonding to fabric a Werner-type Remloncv or Swatches chromi-nuclear complex in which the acido-group is sefi immedb lected from the class consisting of perfiuoroalkanoyl Chmmmudw comm at ly groups and w-hydrofiuoroalkanoyl groups containing from 4 to 18 carbon atoms, said composition consisting essenlg g ga g s, tially of water containing 12-50% by weight of a vinylseconds' sccongis 40 type polymer in the form of a stable, non-ionic emulsion,

and 0.6 to 3.0% by weight of said chromi-nuclear com- Perfluorodecanoic acid 000 15, 000 p Pcrflu r u wic a id---- 2,000 4,000 9. A stable, aqueous phase composition containing a Werner-type chrcmi-nuclear complex, the acido group of which consists essentially of perfluoroalkanoyl groups After the emulsions above had aged for 6 days at room containing 8-10 carbon atoms, suitable for application temperature (ZS-30 C.), they were again used to imon acid sensitive materials without inducing excessive acid pregnate swatches of cotton sateen. The swatches were induced degradation, consisting essentially of water concured for 1 hour at 110 C. The penetration time for taining 3035% by weight of an acrylic ester polymer in the decanoic acid complex-treated fabric had increased to the form of a stable, non-ionic emulsion, and 0.4 to 0.8% 16,500 seconds and the wetting time to 48 hours. For by weight of said chromi-nuclear complex. the swatch treated with the aged butyric acid complex 10. A method of making a composition for impregnatemulsion the penetration time had increased to 5000 sccing fabric, comprising mixing a Werner-type chromi-nuends and the wetting time to 6000 seconds. clear complex, selected from the group consisting of com- We claim: plexes in which the acido group consists essentially of per- 1. A process of rendering a textile fabric highly resistfluoroalkanoyl groups containing from 4 to 18 carbon ant to penetration and wetting by liquid chemical warfare atoms and complexes in which the acido group consists esagenis, Particularly 0f the G-SBTiBS, Comprising; imllfegnfltsentially of omega-hydrofiuoroalkanoyl groups containing ing the textile With a Composite, non-10mm, aqueous emlllfrom 4 to 18 carbon atoms, with a non-ionic aqueous SiOIl Consisting essentially of P y emulsion Selected 6-) polymer emulsion consisting essentially of Water and from from the group Consisting of Polyacrylate emulsions and 12 to 50 percent by weight of polymer selected from the P l/ y acfitate emulsions, in admixture with a Werllefgroup consisting of polyacrylates and polyvinyl esters, and yp chromi-fluclear wmplex in Which the acido group is heating the resultant mixture at a temperature in the selected from the class consisting of perfluoroalkanoyl range 40 C. to C. for a period of time in the range groups and w-hydrofiuoroalkanoyl groups containing from 5 to 18{),mjnutes about 418 carbon atoms, to a dry pick-up of from about 25 to 50% by weight; freeing the impregnated textile of References Cited in the file of this patent excess bath liquor; and drying the wet textile at tem erature and times ranging from about 24 hours at foam UNITED STATES PATENTS temperature to 30 to minutes at temperatures of from 70 2,552,910 Stemman y 1951 about 90 to 120 1 1 einman Sept. 23, 1952 2. The process of claim 1 in which the polymeric con- 2,693,458 Olson 1 4

Claims (1)

1. A PROCESS OF RENDERING A TEXTILE FABRIC HIGHLY RESISTANT TO PENETRATION AND WETTING BY LIQUID CHEMICAL WARFARE AGENTS, PARTICULARLY OF THE G-SERIES, COMPRISING; IMPREGNATING THE TEXTILE WITH A COMPOSITE, NON-IONIC, AQUEOUS EMULSION CONSISTING ESSENTIALLY OF A POLYMER EMULSION SELECTED FROM THE GROUP CONSISTING OF POLYACRYLATE EMULSIONS AND POLYVINYL ACETATE EMULSIONS, IN ADMIXTURE WITH A WERNERTYPE CHROMI-NUCLEAR COMPLEX IN WHICH THE ACIDO GROUP IS SELECTED FROM THE CLASS CONSISTING OF PERFLUOROALKANNOYL GROUPS AND W-HYDROFLUOROALKANOYL GROUPS CONTAINING FROM ABOUT 4-18 CARBON ATOMS, TO A DRY PICK-UP OF FROM ABOUT 25 TO 50% BY WEIGHT; FREEING THE IMPREGNATED TEXTILE OF EXCESS BATH LIQOUR; AND DRYING THE WET TEXTILE AT TEMPERATURE AND TIMES RANGING FROM ABOUT 24 HOURS AT ROOM TEMPERATURE TO 30 TO 90 MINUTES AT TEMPERATURES OF FROM ABOUT 90 TO 120*C.