Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Wearing apparel – fabric – or cloth
Reexamination Certificate
2000-01-05
2002-08-20
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Wearing apparel, fabric, or cloth
C424S443000, C424S449000, C424S402000, C424S618000, C514S495000, C210S758000, C210S764000
Reexamination Certificate
active
06436420
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to textile articles possessing antimicrobial properties and a method for their preparation.
2. Description of Related Art
Textile articles which have been treated to render such articles microbicidal to microorganisms coming in contact with the article are known in the prior art. Such articles include those made from paper, fibers, woven and non-woven textiles and like fabrics which are designed for use in environments such as hospitals, food processing plants, laboratories and other areas where maintenance of germ-free conditions is essential.
For example, U.S. Pat. No. 2,791,518 discloses a method of imparting microbicidal properties to articles such as textiles by immersing the article in a first aqueous solution containing a water-soluble basic nitrogen compound (ammonia) and a monovalent silver salt soluble in said solution, followed by a second immersion in a second solution containing a second salt capable of ion exchange with the silver salt such that a monovalent silver salt precipitate is formed within the article. The formed silver precipitate is sparingly water soluble and imparts microbicidal properties to the articles so treated.
Similarly, U.S. Pat. No. 5,271,952 discloses a method of treating fibers to render them electrically conductive as well as anti-bacterial comprising immersing the fibers in a bath comprising an aqueous solution of a source of divalent copper ions, a reducing agent, sodium thiosulfate and a source of iodide ions, whereby copper iodide is adsorbed into the fibers. Similar techniques for rendering fibers conductive or resistant to bacteria involving the use of copper compounds are disclosed in U.S. Pat. Nos. 4,410,593 and 5,458,906.
It has also been disclosed that materials such as chlorinated hydantions may be grafted to textiles for the purpose of imparting antimicrobial properties, ie Williams et al, 218
th
ACS National Meeting (1999) Abstracts, Cell 32; C&EN September 6, page 36. However, textiles so treated tend to suffer severe diminishment of antimicrobial properties after as few as 5 hours of laundering and are UV unstable over long durations of exposure.
SUMMARY OF THE INVENTION
The invention provides a fibrous textile article containing an antimicrobial agent selected from the group consisting of tetrasilver tetroxide and derivatives thereof interstitially deposited within said article, said agent present in said article in an amount sufficient to impart antimicrobial properties to said article.
The invention also provides a process for imparting antimocrobial properties to a fibrous textile article comprising:
a. providing an aqueous solution containing a water soluble silver salt;
b. contacting said article with said solution for a period of time sufficient to uniformly wet said article with said solution;
c. immersing said wetted article in a bath containing a second aqueous solution containing a strong alkali and a water soluble oxidizing agent and heating said bath for a period of time sufficient to interstitially precipitate tetrasilver tetroxide within said article; and
d. removing said article from said bath.
Textile articles prepared in accordance with this invention, particularly woven and non-woven hydrophilic fabrics, exhibit outstanding antimicrobial resistance with respect to pathogens such as bacteria, viruses, yeast and algae, are resistant to degradation upon exposure to sunlight (ultraviolet light) and maintain their excellent antimicrobial properties even after a number of launderings.
DETAILED DESCRIPTION OF THE INVENTION
Imparting antimicrobial properties to fiber and its derived textile products is achieved in the instant invention by interstitial deposition of the molecular crystal compound tetrasilver tetroxide, i.e., silver (I, III) oxide. Said silver moiety is the subject of several patents. U.S. Pat. No. 5,336,499, the disclosure of which is incorporated herein by reference, describes the anti-pathogenic properties of said silver oxide of formula Ag
4
O
4
and also the mechanism of operation of the molecular device, based on a unique crystal having two monovalent silver (Ag I) ions and two trivalent silver (Ag III) ions in the molecule. The mechanism of killing pathogens described in the patent is based on the differential silver electronic activity between Ag (I) and Ag (III) resulting in electrocution of pathogens, followed by binding chelation of pathogenic surfaces.
U.S. Pat. No. 5,211,855 also discloses the use of Ag
4
O
4
crystals to kill pathogens in utilitarian water bodies such as swimming pools.
An antimicrobial spectrum of Ag
4
O
4
is to be found in a published article written by the instant inventor in the annual R&D issue of
Soap Cosmetics Chemical Specialties
1994, 70, 3 p. 52-59 entitled “Silver (II, III) Disinfectants”, shown in Table 1. The spectrum is based on specifications of the Association of Official Analytical Chemists (AOAC).
TABLE 1
Antimicrobial Spectrum of Ag
4
O
4
MICROORGANISM
MIC* (PPM)
Gram Negatives
Escherichia coll
10231
2.50
Escherichia coll
25254
2.50
Enterobacter cloacae
13047
2.50
Pseudomonas aeruginosa
9027
1.25-2.50
Gram Positives
Bacillus subtilis
6633
5.00
Micrococcus lutena
9341
1.25-2.50
Staphylococcus aureus
0927
2.50-5.00
Staphylococcus aureus
27543
5.00
Staphylococcus epidermidis
12228
0.625
Streptococcus agalactiae
27956
1.25-5.00
Streptococcus faecium
10541
5.00
Streptococcus-pyogenes
7958
2.50
Yeast and Mold
Candida albicans
16404
2.50-5.0
Saccharomyces cerevisiae
2601
1.25
*MIC = Miniinal Inhibitory Concentration.
In said article, reference is made to the fact that monovalent silver is more anti-pathogenic than mercury which is more anti-pathogenic than copper, based on their oligodynamic activity as articulated by J. G. Horsfal in his “Principles of Fungicidal Action” (Chronica Botanica 1956). The relative efficacy of metallic moieties against pathogens has been called the Horsfal series, and is as follows:
Ag>Hg>Cu>Cd>Cr>Ni>Co>Zn>Fe>Ca
The present inventor has found that with respect to a Horsfal series dedicated to silver, the relative efficacy against pathogens is as follows:
Ag
4
O
4
>Ag(III)>Ag(II)>Ag(I)
The term “fibrous textile article” as used herein is intended to encompass a wide variety of materials including paper, natural or synthetic fibers, threads and yarns made from materials such as cotton, rayon, wool, jute, nylon, polyesters, polyacetates, polyacrylics as well as cellulosics in general. More particularly, the term refers to fibers woven into a fabric such as knitting, and non-woven hydrophilic fabrics or webbing used in anti-pathogenic applications such as in the medical field, hospitals, biotechnology and food and dairy processing. Exemplary textile products of this genre include bandages, gauze, bandage pads, skin patches, work clothes (both disposable and reusable), bed sheets, masks, dust cloths, safety belts, surgical gowns, ambulance blankets, stretchers, filter materials, diapers, underwear, pajamas, video display terminal screens and the like.
For some antimicrobial applications, Ag
4
O
4
crystals may be deposited within the interstices of fibrous articles by simply soaking the article in an aqueous dispersion of the crystals or by combining the crystals with a carrier medium and applying this composition to the fibrous article. This method of physical incorporation of the crystals is useful where the article is composed of low density or loosely associated fibers such as bandage pads, gauze pads and loosely non-woven products, and particularly laminated products wherein the treated fibrous article is subsequently sandwiched between one or two peelable layers which tend to keep the crystals trapped in the fibrous article until ready for use. Also, antimicrobial paper products may be made by simply mixing an aqueous dispersion of the Ag
4
O
4
crystals with paper pulp prior to calendaring the pulp.
However, physical incorporation of the crystals is less effective where the treated articl
Di Nola-Baron Liliana
Marantech Holding LLC
Page Thurman K.
Pennie & Edmonds LLP
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