US2938814A - Method of producing antiseptic articles - Google Patents

Description

United States Patent METHOD OF PRODUCBWG ANTISEPTIC ARTICLES Sylvan I. Cohen, Flushing, and Martin S. Frant, Ossining, N.Y., and Frank J. Sowa, Cranford, N.J.; said Cohen and said Frant assignors to Galiowhur Chemical Corporation, New Yorlr, N.Y., a corporation of New York No Drawing. Fiied July 19, 1954, Ser. No. 444,361

4 Ciaims. (Cl. 117-1385) The present invention relates to antiseptic articles such as nylon, nylon filaments and brushes, particularly toothbrushes having synthetic plastic heads and handles with nylon bristles, and to the production of such antiseptic articles by treating them with solutions of phenyl mercury compounds to provide them with a durable, chemically adherent deposit having excellent germistatic and germicidal properties, together with great stability and high resistance to leaching.

In our application Ser. No. 443,423, filed July 14, 1954, now abandoned, we have described and claimed certain solutions of phenyl mercury compounds, the production of such solutions and the results which can be achieved therewith. These solutions are especially suited or adapted for application to various articles, particularly those composed of nylon or having a nylon component such as nylon bristles, and the present invention is directed to the method of treatment of such articles with such solutions and to the antiseptic articles thereby produced.

In accordance with the invention and as a specific example thereof, nylon in filamentary form suitable for the fabrication of toothbrush and other bristles is passed through a bath of phenyl mercury lactate in lactic and formic acids in a continuous manner at such a rate that every portion of the nylon is wetted with the solution for approximately one minute. It is to be understood, however, that alternatively, the nylon or other article may be subjected to the solution of the phenyl mercury compound in other ways, as by immersion or spraying. The processing is carried out at room temperature and after the nylon has had the indicated length of contact with the solution it is then dried under gentle drying conditions as by means of Warm air currents or low temperature drying ovens, except that where time permits the treated article may be allowed to dry in the air under ambient temperature conditions. It has been found best, and is therefore preferred, to subject the nylon or other article to the action of the solution for a period of about one minute as above indicated, but the precise time factor in any given instance depends somewhat upon the nature of the article and its physical configurations and size and, in general, we have found that treatment with the solution from about ten to sixty seconds is adequate, but that treatments up to one hour or more are permissible without adversely affecting the results, although such is unnecessary.

The bath or solution through which the nylon or other article is passed or in which it is immersed is essentially composed of phenyl mercury lactate in lactic and formic acids, the amount of formic acid being sufiicient to provide free formic acid in the final solution and to reduce the content of equivalent mercury of the solution to approximately l%. The equivalent of mercury may, however, range from approximately 0.25 to 5% but for best and most economical results approximately 1% of mercury is preferable. Instead of employing phenyl mercury lactate, we may utilize any phenyl mercury compound which, with lactic acid, forms phenyl mercury lactate. Examples of such phenyl mercury compounds are phenyl mercury acetate and phenyl mercury hydroxide.

In processing nylon and other articles with the aforementioned solutions, it is important to avoid any drastic treatments or conditions which would cause adverse alteration or change in the nature of the solutions or the articles themselves, particularly in view of the fact that solutions containing phenyl mercury lactate and lactic and formic acids are rendered unstable at temperatures approximating the boiling point of Water. For instance, when such a solution is subjected to boiling for purposes of concentrating it, as has been heretofore proposed, a reducing action occurs resulting in the formation of metallic mercury as a precipitate and a reduction in the equivalent mercury content of the supernatant liquid. Such boiled solutions therefore lack stability and are not suitable for shipment and treatment of articles at considerable distances from the point of production of the solutions. We, therefore, carry out treatment of the articles with these solutions at or about room temperature and in any event avoiding a temperature which would adversely aifect the solutions. Since entirely satisfactory results are obtainable at room temperatures, it is neither necessary nor desirable to raise the temperature of the treating solution although there is no objection to warming the solution or using it in localities or at times when the ambient atmospheric temperature is high.

The nylon or other article or material may be processed in accordance with the invention at any convenient stage in the manufacture or fabrication of such article or material. Thus, nylon in sheet, filamentary or other physical form or shape may be treated and the antiseptic nylon thus produced may be subsequently finished and incorporated into the final articles, such as brushes. The invention is particularly adapted for the treatment of toothbrushes having synthetic plastic heads and handles with nylon bristles, although other materials may be satisfactorily rendered antiseptic, such as Siberian pig bristles and those plastices and materials which are commonly employed in the manufacture of brushes and other articles.

Articles treated with the solutions above referred to and then dried under mild drying conditions are found to be provided with a chemically adherent, integrated deposit of a phenyl mercury compound. This chemically adherent deposit'is characterized not only by excellent germistatic and germicidal activity but by resistance to leaching by water and by dentifrices or detergents. The chemical adherence is so strong and tenacious that it persists for the useful life of the article itself. In the case of nylon bristles of toothbrushes, tests have shown that, after treatment, such bristles contain the equivalent of approximately (MS-0.030% mercury, which, even under accelerated leaching test conditions, is reduced by only about 0.001% per day, so that, under the normal or usual conditions of use, the chemically adherent deposit lasts throughout the useful life of the article.

Formic acid appears to play a vital role in the effective treatment of nylon articles, toothbrushes and other brushes and articles with the new solutions. In the absence of the formic acid, the results of the invention cannot be obtained. The formic acid appears to contribute durability and resistance to leaching and, when formic acid is incorporated, tests showed practically no loss of initial activity after minutes of brushing, whereas, when formic acid was omitted, comparative tests showed practically no activity after only 45 minutes of brushing.

For eifective results, a phenyl mercury compound must r and articles.

be used which is of a selective character in that all phenyl mercury compounds do not produce useful results. This was found to be true, for example, with phenyl mercury linoleate. Therefore, in accordance with the present invention, the solution must contain phenyl mercury lactate or a phenyl mercury compound such as the acetate or hydroxide which, with lactic acid, forms phenyl mercury lactate and lactic acid and, in addition, formic acid must be present in an amount sufiicient to provide some free formic acid in the solution and also to bring the equivalent of mercury to the desired value in the range of 0.25 to 5%, a 1% equilavent of mercury having been found to be best.

Antiseptic articles produced in accordance with the invention are antiseptic or bacteriostatic by the standards of the Food and Drug Administration circular 198 method for bristles measuring 0.5 mm. in thickness and 8.0 mms. in length. The inhibitory zone must be at least 6.5 x 8.0 mms. if the bristles are severed to the above length for testing after treatment. Nylon bristles rendered anti-, septic in accordance with the invention meet this requirement and furthermore exhibited suflicient bacteriostasis and resistance to further loss of activity even after brushing tests of 300-390 minutes.

The term ,nylon is used herein in the same sense as in our aforesaid application. The invention is applicable, however, to other synthetic plastics and materials, such as'butyrate resin and the plastics commonly employed for toothbrush heads and handles and for other brushes Treatment of such articles in accordance with this invention does not dissolve, alter or otherwise undesirably attack such materials and does not reduce their useful life. It is to be further noted that the treated bristles or other articles show bactericidal killing action and, consequently, the invention. produces results beyond bacteriostasis. The tests for bactericidal activity were made in accordance with those set forth in our aforesaid application which show that, where contact occurred from 1-7 hours, most of the subcultures (in the proporcoccus pyogenes var. aureus) had been killed and that where contact occurred for about 24 or more hours during the tests all subcultures failed to grow.

We claim:

a 1. A method of producing antiseptic nylon and plastic articles which comprises subjecting such articles to treatment with a solution of phenyl mercury lactate in lactic acid and suificient formic acid to reduce the equivalent mercury content to about 0.25-5% and drying the articles, thereby producing a chemically adherent deposit of phenyl mercury formate in and on said articles to render the articles durably germistatic and germicidal through out their'useful life.

2. The method of claim 1, in which the articles are nylon in filamentary form and are continuously passed through a bath of the said, solution at a rate such that every portion thereof is immersed in the solution at room temperature for at least about 10-60 seconds.

3. The method. of claim 1, in which the articles are plastic brushes with nylon bristles. I

4. The method of claim 1, in which the equivalent mercury content is approximately 1%.

References Cited in the file of this patent UNITED STATES PATENTS 2,099,888 Hill Nov. 23, 1937 2,411,815 Sowa Nov. 26, 1946 2,423,261 Sowa July 1, 1947 2,423,262 Sowa July 1, 1947 2,479,275 Sowa Aug. 16, 1949 2,507,299 DAlelio May 9, 1950 2,637,677 Diner stein 'May, 5, 1953 FOREIGN PATENTS 543,291 Great Britain Feb. 18, 1942 OTHER REFERENCES Rayon and Synthetic Textiles (May 1950), vol. 31, No. 5.

Textile Colorist (February 1940), page 92.