US 3061469 A
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United States Patent Office 3,001,469 Patented Oct. 30., 1962 3,061,469 ANTIBACTERIAL TEXTILE FABRECS Milton Manowitz, Fair Lawn, and Wiiiiam S. Gump,
Upper Montciair, N.J., assignors to The Givaudan Corporation, New York, N.Y., a corporation of New Jerse F3 Drawing. Filed Nov. 5, 1959, Ser. No. 851,007 4 Claims. (Cl. 117-4385) This invention relates to novel antibacterial textile fabrics and to novel processes for preparing same.
An object of this invention is to furnish antibacterial textile fabrics capable of substantially retaining their antibacterial effectiveness after repeated launderings.
Another object of the present invention is to provide the aforesaid fabrics in a technically simple and commercially feasible manner.
Other objects of this invention will become apparent from the following detailed description.
We have found that the objects of this invention may be attained by bringing a dilute aqueous solution of the complex salt of silver nitrate and ethylenethiourea into contact with a textile fabric and drying the same, e.g., by air drying, whereby a small amout of said complex salt is retained by said fabric.
We are aware that the incorporation of antibacterial substances into textile fabrics in order to render the same antibacterial has been suggested by others. The incorporation of substances such as quaternary ammonium compounds, e.g., higher alkyl dimethyl benzyl ammonium chloride; organometallic compounds; and others may be noted. The resulting articles are, for the most, nondurable in antibacterial effect because they, among other things, do not resist normal laundering processes on account of the detergents, bleaching agents, or other materials commonly employed in such processes.
The complex salt formed from 4 moles of ethylenethiourea and 1 mol of silver nitrate useful in accordance with this invention, and its method of preparation, are described in the Journal of the Chemical Society (London), 1928, page 150. The aforesaid complex salt may be referred to as tetrakisethylenethiocarbamido-argentous nitrate. It is a white solid, melting at 96'9'7 C., solusic in water, very slightly soluble in alcohol and insoluble in other organic solvents, in general. In aqueous media, the aforesaid reaction product reacts with the sodium salt of various acids, often forming water-insoluble derivatives. It exhibits a bacteriostatic end point of about 20 to 50 parts per million against common gram-negative and gram-positive organisms.
Relatively small amounts of the aforesaid complex silver salt, hereafter referred to as A-l51, are sufficient to impart laundry-resistant, antibacterial properties to textiles. Amounts as low as about 0.02 percent to about 2.0 percent of the total dry Weight of the treated fabric have proved satisfactory. However, it is preferred to use amounts of the order of about 0.1 percent to about 0.5 percent, on the same basis. The upper limit of the amount of A-l51 employed is determined by practical considerations, etc. For this reason no practical advantageous results flow from the use of larger amounts of A-l5l, although larger amounts in general do enhance the antibacterial properties of the treated fabric.
The incorporation of the predetermined amount of A-151 into textile fabric will depend on the method employed, as is well-known to those skilled in the art. For example, if the well-known technique referred to as padding is employed, under conditions such that the fabric picks up an amount of aqueous solution of A-151 equivalent to 75 percent by Weight of the textile fabric itself, we have found that solutions from about 0.026 percent to about 2.6 percent in strength, i.e., by weight of silver product based on the total solution, yield treated textile fabrics having about 0.02 percent to about 2.0 percent by weight of reaction product on the dry treated fabric. Similarly, following the same padding technique, aqueous solutions of about 0.13 percent to about 0.65 percent strength, on the aforesaid basis, yield treated fabrics having from about 0.1 percent to about 0.5 percent by weight on the dry treated fabric.
If desired, other methods known to the art may be used to incorporate the aforesaid silver salt on the fabric.
it has been found that the advantageous results of the present invention are obtained with textiles in general. Thus, e.g., cotton, nylon and wool may be specifically mentioned by way of illustration and not by way of limitation. Fabrics made from other cellulosic, natural or synthetic, fibers may be used, if desired.
As already noted, fabrics treated in accordance with our invention possess laundry-resistant, antibacterial properties, in addition to the properties attributable to the fabric itself. This resistance was found, irrespective of the laundering agent, i.e., whether the laundering agent was soap or synthetic detergents of various kinds. The treated fabrics are not adversely affected by bleaching agents, e.g., immersion in aqueous sodium hypochlorite does not affect the color of white fabrics nor the antibacterial properties of the treated fabric.
Specific uses of fabrics treated in accordance with our invention include use in clothing items, diapers, and hospital fabrics such as blankets, sheets, etc. Practically speaking, fabrics treated in accordance with the present invention are non-toxic.
The method employed to test for the antibacterial properties against gram-positive organisms is the agar plate method as given in Circular 198, December 1931, of the U8. Food and Drug Administration.
To test for activity against gram-negative organisms and to test some practical applications of these fabrics, a modified urease test procedure was used. This method consisted of placing a 1 inch square of fabric on the bottom of a 4 oz. jar, saturating the fabric with urine, inoculating with Proteus mirabilis and incubating the jars tightly capped at 37 C. A piece of pH paper suspended from the jar cap was used as a visual means of detecting ammonia production due to bacterial growth and periodically the jars were opened and the presence of ammonia determined organoleptically.
The laundry conditions employed involved the immersion of 5 gram samples of fabric in Erlenmeyer flasks containing ml. of a 0.2 percent solution of a detergent or soap, e.g. Fab arylalkyl sulfonate powder (Colgate-Palmolive) in Water at 45 C., and agitating the flasks for 12 minutes on a rotary shaker (New Brunswick Scientific Co.). The laundered fabrics were rinsed by agitating in 100 ml. of hot water (45 C.) three times.
In order more fully to explain our invention, we give the following examples by way of illustration and not by way of limitation.
Example I Following the method above described, standard 2.66 oz. of bleached, completely de-sized, mercerized cotton sheeting (Style 405, Test Fabrics Inc.) was treated with aqueous solutions of tetrakisethylenethiocarbamido-argentous nitrate (A151) of various strengths so that the concentrations of material retained by the cotton sheeting were 0.02%, 0.05%, 0.1%, 0.25%, 0.50%, 0.75% and 1.0%.
The so-treated sheetings were exposed to the laundering procedure described above and tested in accordance with the aforementioned F.D.A. method, Circular 198.
It was found that even the fabric with only 0.02 percent of A-lSl gave a measurable zone of protection even after laundering. Fabrics with 0.05 percent of compound A-151 exhibited a wide zone of protection even after launderings. Fabrics with 0.1 percent of A-l51 and higher exhibited strong bactericidal properties after launderings. Fabrics with 0.25 percent or more of A-l5l still showed large zones of inhibition following 45 lauuderings.
Where the foregoing example Was repeated, employing other laundering agents in place of Fab detergent, the results were substantially the same. The other agents employed were soap powder (Lever Brothers), Tidealkylaryl sulfonate (Procter and Gamble), Lux-soap flakes (Lever Brothers), All-non-ionic detergent (Lever Brothers), and Duz-anionic detergent (Procter and Gamble).
Example II The procedure of Example I was repeated twice, once employing nylon fabric (taffeta nylon, semi-dull staple), in place of the cotton sheeting, and the other time employing wool fabric, in place of the cotton sheeting.
The results showed that the treated nylon and wool retained their antibacterial properties after repeated launderings, but not to the same extent as in the case of cotton sheeting.
Example III Samples of the untreated cotton sheeting used in Example I and the same cotton sheeting treated in accordance with the procedure described herein above so as to contain (a) 0.10% and (b) 0.25% of A-151 on the dry weight of the treated sheeting were exposed to the modified urease test described above.
The samples of untreated cotton sheeting showed a visual pH change after 1 /2 hours of incubation and a significant ammonia odor after 3 to 4 hours.
The treated samples, even after 5 launderings as aforesaid with Fab arylalkyl sulfonate, showed no pH change or ammonia odor throughout a 3 day incubation period. This was even true of the treated fabric containing 0.25 percent of A-l51 after 15 launderings as aforesaid.
Example IV The cotton sheeting employed in Example I was treated in accordance with the aforementioned process of this invention so as to yield 21 treated fabric containing 1.0 percent by weight of A-151.
Samples of the so-treated fabric were separately subjected to the aforementioned padding procedure in 1.0 percent aqueous baths of the sodium salt of various acids and sodium hydroxide. These after-treated fabrics as well as a sample of the untreated cotton sheeting and a sample of the cotton sheeting containing 1.0 percent of A-15 l but with no after-treatment were subjected to the afore described laundering procedure using Fab" arylalkyl sulfonate. The results showed that the untreated sheeting gave no protection at all and that the sheeting containing A-151, with no after-treatment, gave substantially the same antibacterial protection as was true of the after-treated fabrics, even after 15 launderings.
The sodium compounds used in the after-treatment were sodium benzoate, tri-sodium phosphate, sodium carbonate, mono-sodium, citrate, sodium chloride, sodium sulfate, sodium thiocyanate, sodium tripolyphosphate, sodium oleate, sodium benzenesulfinate, and sodium hydroxide.
Accordingly, wherever the context of the specifications and claims permit or require, the term complex salt of ethylenethiourea and silver nitrate is to include, as equivalents thereof, products made by reacting said c0u1- plex salt with the aforementioned Water-s0luble sodium compounds as well as known equivalents thereof.
The foregoing illustrates the practice of this invention, which, however, is not to be limited thereby, but is to be construed as broadly as permissible in view of the prior art and limited solely by the appended claims.
1. An article of manufacture comprising textile fabric having uniformly incorporated thereon the complex salt of silver nitrate and ethylenethiourea in a minor proportion sufficient to impart laundry-resistant, antibacterial properties to said textile fabric.
2. An article of manufacture in accordance with claim 1, wherein said textile fabric comprises cotton fibers.
3. An article of manufacture in accordance with claim 1, wherein said minor proportion is within the range from about 0.02 percent to about 2.0 percent, based on the total dry weight of the treated fabric.
4. An article of manufacture in accordance with claim 2, wherein said minor proportion is within the range from about 0.02 percent to about 2.0 percent, based on the total dry weight of the treated fabric.
References Cited in the file of this patent UNITED STATES PATENTS 2,562,488 Fuchs July 31, 1951 2,813,059 Davis et al Nov. 12, 1957 OTHER REFERENCES Journal of the Chemical Society (London), 1928, page 150.