MXPA01000801A - Method for the manufacture of antimicrobial articles - Google Patents

Abstract

A method for making an antimicrobial article is described, the method comprising:providing a substrate;forming a solution comprising a chelating polymer and a metal ion;depositing the solution on the substrate;drying the substrate to form a coated substrate;and adding a potentiator to the coated substrate to form the antimicrobial article. Forming of the solution comprises (A) selecting a chelating polymer from the group consisting of polyglucosamines, ethylene acrylic acid copolymers, polycarboxylic acids, and polyamines, (B) dissolving the chelating polymer in acid to form an acidic solution, (C) preparing an aqueous solution of the metal ion, preferably by selecting a salt of the metal ion and dissolving the salt in water, and (D) combining the aqueous solution of the metal ion and the acidic solution. The addition of the potentiator to the coated substrate is accomplished by dissolving the potentiator in water to provide a potentiator solution, treating the coated substrate with the potentiator solution, drying the substrate to provide the finished antimicrobial article. The invention provides a method for the treatment of any of a variety of substrates to thereby render the substrate resistant to certain microbial growth.

Description

METHOD FOR THE MANUFACTURING OF ANTIMICROBIAL ARTICLES The present invention relates to a method for the manufacture of articles resistant to microbial growth and to a method for the treatment of a substrate for imparting antimicrobial properties to the treated substrate.

BACKGROUND OF THE INVENTION The control of mold, mildew, algae, fungi, and other microbes or microorganisms in moisture or humid environments has been a matter of concern for a long time. To remove microbes from an area and prevent their occurrence, biocides have typically been used, such as mildecides, antimicrobials, antiseptics, disinfectants, sanitizers, algaecide germicides, limocides, antiseptic agents, or preservatives.

Absorbent articles used for cleaning (eg, sponges and cleaning cloths) can house microorganisms such as bacteria and fungi that grow and multiply rapidly in humid environments. In the food service and medical industries, sanitation and the prevention of the spread of infections is of extreme REF. NO.126569 importance. Consequently, the use of materials that can control or prevent the development of unwanted microorganisms is desired. Several criteria have been applied to the problem of microbial development in articles such as, for example, sponges and items such as cleaning cloths and other types. Cellulose sponges treated with germicides and biocides have been used with some success, including alkali metal salts in combination with quaternary ammonium compounds as well as alkali metal montmorillonite clays. Metallic dialkyl dithiocarbamates have also been used as biocides in pigmented sponges. The sponges prepared by these methods, although initially effective, do not have a long-lasting antimicrobial activity because the biocides tend to be washed from the sponges with the rinses with water or when the article is used in cleaning applications.

One criterion for introducing a long-lasting microbial agent into an absorbent sponge is described in US 5,541,233 (Roenigk). Long lasting antimicrobial sponges are formed by mixing a metal ion and a dispersion of a chelating polymer with the viscose cellulose used to make the sponge, followed by treatment with heat or acid which causes coagulation and regeneration in a sponge. The sponge is rinsed, leaving a porous structure with the chelating polymer in it. This is followed by the addition of an enhancer (i.e., an antimicrobial agent) that is believed to react with the metal ion.

However, there is a need for methods for making long-lasting antimicrobial articles that do not require regeneration or further processing of the final article.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a method for the preparation of antimicrobial articles. These articles provide long-lasting protection against the growth of a variety of microbes such as mold, mildew, algae, fungi, and the like.

In one aspect, the invention is a method for making an antimicrobial article comprising: provision of a substrate; forming a solution comprising a chelating polymer and a metal ion; deposition of the solution in the substrate; drying the substrate to form a coated substrate; and adding an enhancer to the coated substrate to form the antimicrobial article.

The formation of the solution comprises (A) the selection of a chelating polymer from the group consisting of polyglucosamines, copolymers of ethylene acrylic acid, polycarboxylic acids, and polyamines, (B) the dissolution of the chelating polymer in acid to form an acid solution, (C) the preparation of an aqueous solution of the metal ion, preferably by the selection of a salt of the metal ion and the dissolution of the salt in water, and (D) the combination of the aqueous solution of the metal ion in the acid solution. A preferred polyglucosamine is chitosan. The metal ion is preferably selected from the group consisting of zinc, zirconium, iron and copper.

To deposit the solution on a substrate, a variety of methods are available such as immersing the substrate in the solution and allowing excess solution to drain off the substrate after immersion. The addition of the enhancer to the coated substrate is achieved by dissolving the enhancer in water to provide an enhancer solution, treating the coated substrate with the enhancer solution by drying the substrate to give a finished antimicrobial article. The enhancer can be selected from the group of alkyldithiocarbamates, thiazoles, imidazoles, pyrithione or their mixtures.

The invention provides a method for treating any of a variety of substrates to thereby provide the substrate with resistance to some microbial growth, as evidenced by the test results set forth in the present Examples. By way of example, the invention provides a method for the application of a preferred antimicrobial complex to any of a variety of substrates. In particular, a microbial-based chitosan complex can be applied to such substrates for the purpose of giving the substrate a high resistance to microbial growth such as fungal growth and the like. In particular, a chitosan-metal-pyrithione complex can be easily applied to virtually any surface to produce a finished article suitable for cleaning applications and the like with antimicrobial properties that will resist repeated use of the article even after significant exposure to water.

Those skilled in the art will further appreciate the utility, novelty and non-obviousness of the present invention in consideration of what remains in the description including the detailed description of the preferred embodiment, and the appended examples and claims.

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a solution of a metal ion and a chelating polymer is prepared and deposited on a substrate. After the substrate is dried, a solution containing an enhancer is added to impart long-lasting antimicrobial characteristics to the substrate. The antimicrobial article is useful in certain cleaning applications (for example, as a sponge or sponge for scrubbing or scrubbing), or any application where the antimicrobial characteristics may be beneficial.

Metal ions suitable for use in the present invention are capable of forming bonds (eg, covalently coordinated bonds) with molecules which are generally referred to as ligands or chelating agents. Suitable metals include transition metals (ie, groups IB-VIIIB of the periodic table of elements) available as water-soluble salts. In addition, the main group metals capable of forming a complex with the chelating polymer of the present invention may also be suitable. Useful metal ions include Zn + 2, Zr + 2, Fe + 2, Cu + 2.

Such metal ions are available as water soluble salts, ie, for example, acetate, chloride, and sulfate salts of the metals including their hydrates. Based on commercial availability and the relatively low cost of the soluble salts of zinc in water, a preferred metal ion is Zn + 2. Preferred zinc salts include zinc acetate and zinc chloride.

In the solution, the metal forms a complex with the chelating polymer. Chelating polymers suitable for use in the present invention are preferably capable of forming a film when coated on a surface. Suitable polymers include, for example, polyglucosamine, ethylene acrylic acid copolymer, polycarboxylic acid, alkylbenimines and polyamine. A preferred chelating polymer is a polyglucosamine also referred to as chitosan, the deacetylated derivative of the chitin polysaccharide (β- (1, 4) -poly-N-acetyl-D glucosamine) and a natural by-product of the shrimp and crab industries.

In the method of the present invention, the chelating polymer is dissolved in a suitable solvent, including water as well as polar organic solvents such as alcohols and ketones. Water is the preferred solvent. Upon dissolving the chelating polymer, it may be desired to add sufficient acid (eg, acetic acid) or base (eg, NaOH) to facilitate dissolution of the polymer and assist in the production of a homogeneous solution. When the chelating polymer is chitosan, sufficient acid is added to provide an acidic pH such that the acid protons the amino groups in the chitosan to solubilize it in the solution. Typically, a solution with a pH of about 6 or less is sufficient to dissolve the chitosan. Acids suitable for the dissolution of chitosan include organic and inorganic acids. Without limitation, suitable organic acids include acetic, adipic, formic, lactic, malic, malonic, propionic, pyruvic, and succinic. Suitable inorganic acids include, for example, hydrochloric and nitric.

The chelating polymer, and any added acids or bases, are dissolved in the solution typically by stirring for a sufficient time (eg, several minutes). Subsequently, the metal ion is added to the polymer solution, either as a salt or as a solution of the metal salt. A convenient technique for the addition of the metal ion to the solution is to first make a dilute solution of the metal salt in the desired solvent and add it with stirring to an equal amount of a dilute solution of a chelating polymer. Then this resulting ion / polymer solution can be applied to a substrate.

Optionally, additives can be included in the ion / polymer solution. For example, one or more pigments, pigment fixing agents, processing aids (e.g., wetting agents, defoamers, viscosity reducers, thickeners), addition promoters, antioxidants and the like to the ion / polymer solution may be added. that is applied to the substrate. The pigment can be used in the ion / polymer solution to match the color of the coating with that of the substrate, or possibly as a color code identification additive for the finished antimicrobial product. Immobilizing agents in the ion / polymer solution immobilize the chelated polymer in the substrate. An immobilizing agent is epoxysilane. Other immobilizing agents such as aziridine or other known cross-linking agents can also be used. Without adhering to any particular theory, the cross-linking agent or the immobilizing agent will react with the hydroxyl groups on the chitosan and the substrate to further bind the antimicrobial agent to the substrate. A preferred additive for the ion / polymer solution is 3- (trimethoxysilyl) propyl glycidyl ether (commercially available under the trade designation A-187 from OSi Specialties Inc., Danbury, Connecticut).

It is contemplated that the ion / polymer solution may also be blended with a binder that can be coated of the type normally used in the manufacture of the finished article. For example, in the manufacture of non-woven articles, it is typically required that the binder bind to its fibers with one another at its intersection and / or contact points and to keep the finished articles in a preferred configuration. Preferably, the binder will be miscible with the ion / polymer solution. Where the above binder is a component of the finished product, the ion / polymer solution of the invention can be introduced into the manufacturing process with the binder in the same process step. Suitable binders compatible with the ion / polymer solution of the invention include water-soluble binders such as, for example, polyvinyl alcohol (PVA), and acrylic or phenolic dispersions or networks. Even if the finished item would not normally require the use of a binder, the ion / polymer solution can be mixed with such a binder in order to improve the adhesion of the metal ion / chelating polymer with the substrate. Those skilled in the art will appreciate that the ratio of ion / polymer solution to binder may possibly vary by the specific application. Therefore, the relative amounts of ion / polymer solution and binder will be determined empirically according to the nature of the article being manufactured and its intended use.

The ion / polymer solution can be applied to a substrate by a variety of known methods of coverage, including spraying, blade coverage, roll coverage, spinning coverage, immersion coverage, and the like. The method of coverage selected for the manufacture of a particular article may depend on the form of the substrate as well as other factors known to those skilled in the art. It is generally desired to have an ion / polymer solution deposited over the entire available surface of the substrate, but this is not essential. The desired amount of coverage depends on the type and application for a particular substrate. Typically, a minimum amount of enhancer is in the order of 30 ppm based on the sensitivity of current analytical methods. Lower levels of the enhancer may continue to be effective in certain applications against certain bacteria. More preferably, the level of enhancer is between 1500 and 3000 ppm based on the total weight in grams of the dry substrate. Below the level of 1500 ppm, the effectiveness of the antimicrobial article can be compromised against certain fungi, as determined by the ASTM Fungal Challenge (ASTM Fungal Susceptibility Test) set forth below in the Examples.

After the ion / polymer solution is deposited on the substrate, the coated substrate is dried at room temperature or at elevated temperatures for a sufficient time to remove the solvent. Preferably, drying is achieved by heating using a conventional drying oven operated at a temperature from about 105 ° C to about 120 ° C sufficient to extract the solvent, dry the chelated polymer and form a suitable film on the treated substrate. At temperatures above 120 ° C, some discoloration of the chelated polymer may occur. At temperatures below 150 ° C, the drying rate can be undesirably slow.

If a binder has been used in the manufacture of the article, the ion / polymer solution may have been blended with the binder or applied to the binder. In any case, a heat treatment is typically needed to cure the binder. In this case, the temperatures can be in a range of up to 150 ° C, depending on the type of binder and the thickness of the substrate. In this case, the use of a substrate of a darker color may be preferred to mask the aforementioned discoloration.

After the article is dried, it is preferably treated with another solution containing an enhancer. The "enhancer" as used herein refers to an antimicrobial agent capable of binding a metal ion. It should be noted that the selection of the enhancer depends on the coordination chemistry of the metal ion. For example, if the bonds between the chelating polymer and the metal ion can be completely displaced by an enhancer, the duration of the complex in the chelating polymer can be compromised. Then, the use of such an enhancer would not be desirable. The enhancer solution can be applied by known coating methods such as those mentioned above for the application of the ion / polymer solution. To maximize the antimicrobial activity of an article prepared by this method, preferably all of the available surface of the coated substrate is exposed to the solution of the enhancer. However, a desired level of antimicrobial activity can be achieved without coating the entire available surface.

Suitable enhancers include, but are not limited to alkyl dithiocarbamates, imidazoles, pyrithione, and mixtures thereof. Alkyl dithiocarbamates include those in which each alkyl group of the carbamate has up to eight carbons. The alkyl groups can be linear or branched. Representative dithiocarbamates include dimethyl dithiocarbamate, diethyl dithiocarbamate, dibutyl dithiocarbamate, methyl ethyl dithiocarbamate, methyl propyl dithiocarbamate, methyl butyl dithiocarbamate, dihexyl dithiocarbamate, dioctyl dithiocarbamate, and the like. A preferred alkyl dithiocarbamate is dimethyl dithiocarbamate, commercially available under the trade designation of "Vancide 51" from R.T. Vanderbilt of Norwalk, Connecticut. Imidazole is a five-membered heterocyclic containing an N-H group and an unsaturated nitrogen. An example of an appropriate substituted imidazole is 2- (4-thiazolyl) benzimidazole. Thiazoles are five-membered rings containing nitrogen and sulfur. An example of a suitable thiazole is 2-mercaptobenzothiazole. 2-mercaptobenzothiazole is available under the commercial designation "Captax" from R.T. Vanderbilt A particularly preferred enhancer is l-hydroxy-2 (1H) -pyridinothione, referred to in the art as pyridinothione and as pyrithione. Pyrithiones are typically sold as sodium salts and are commercially available, for example, under the trade designation of "OMADINE" from Olin Corporation of Cheshire, Connecticut in 40% aqueous solutions. The enhancer is applied to the substrate in an amount sufficient to produce an antimicrobial effect in the finished article, as explained herein.

Various types of substrates are suitable for use in the present invention. Preferably, the substrates are those considered useful in applications where antimicrobial activity is advantageous. This includes filtration applications such as vacuum bag, oven filter, and respiratory masks. Also personal products such as hair or makeup brushes made of synthetic or natural bristles as well as body sponges can be manufactured or treated in accordance with the invention. It may be desirable to make an antimicrobial plastic plating (eg, polyvinyl chloride (PVC) films) according to the method of the invention. Cleaning, scouring or scrubbing articles or cleaning surfaces are very convenient for manufacturing according to the method of the present invention. Such items include brushes, mops, brooms, as well as small cleaning items such as sponges, non-woven fabrics or tablecloths, paper goods, and conventional textiles such as towels, dishcloths, and bibs. The substrate may be non-absorbent, such as those in sponges containing abrasives (e.g. scouring or scrubbing sponges and polishing sponges). The substrates may comprise any of a variety of natural or synthetic materials. A particularly useful form of substrate is a fiber made of natural and / or synthetic materials and articles made with such fibers. Suitable natural fibers include cotton, linen, hemp, ramie, rayon, jute, regenerated cotton, cotton wool, and pulp fibers. Suitable synthetic fibers include viscose rayon, cupra onium rayon and the like, "polyolefin fibers such as polyester, polypropylene, and fibers of polyamide, polyvinyl alcohol, nylon and acrylic fibers." Polymeric foams can be used as the substrate in the process of the invention. , such as polyurethane foams.

Non-woven fabrics are particularly useful as substrates due to their utility in the manufacture of cleaning articles and / or for scrubbing or scrubbing. Non-woven fabrics can be absorbent (such as those used as cleaning wipes) or non-absorbent (such as those used in scrubbing or polishing applications). Non-woven fabrics used for scouring or polishing applications may contain abrasive particles. Suitable non-woven fabrics of a construction, exposed to the air, carded, stitched, wet spun, or blown can be made. A typical non-woven fabric is characterized as a high open, three-dimensional non-woven substrate, exposed to the air such as that described by Hoover et al. In U.S. Patent No. 2,958,593. Also, the non-woven fabric can be a low density nonwoven article formed by a multiplicity of pleated filaments (e.g., thermoplastic filaments) wherein at one end of substantially all of the filaments, these are joined at a first binding site and a second end of substantially all of the filaments that are joined at a second binding site with an unattached portion of the array of filaments between the first and second binding sites. A nonwoven fabric of this type is described in U.S. Patent Nos. 4,991,362 and 5,025,596, both to Heyer et al.

The nonwoven fabric preferably comprises a first main fabric surface, a second main fabric surface, and an intermediate fabric portion extending between the first and second major fabric surfaces. The fabric is made of an appropriate synthetic fiber capable of withstanding the temperatures at which the impregnation resins and the adhesive binders are cured without deterioration. The non-woven fabrics preferably have a weight per unit area of at least 50 g / m2, and can be in a range of up to 200 g / m2.

Non-woven fabrics can be reinforced and consolidated by methods that intertwine the fibers. These methods include basting with needle, hydroentangled, and the like. Non-woven fabrics can also be reinforced by stitching or other conventional textile methods. The union by points is a method of joining at least two fabrics or at least two layers of the same fabric. The method is useful in increasing the thickness of non-woven fabrics and tends to increase their durability. The fibers of the non-woven fabric are typically bonded to one another at their points of intersection and / or contact by the use of a binder. Suitable binders include resinous adhesives, for example, such as phenolic water-based thermosetting resin. Fusion-bonded fibers may be used in the non-woven fabric either alone or in combination with the above adhesives. When exposed to elevated temperatures, the melt-bonding fibers will soften and / or melt and, upon cooling, adhere to other fibers in the fabric.

Substrates of non-woven fibers of this type can also contain abrasive particles. Typically the particles are mixed with a binder and applied to the nonwoven fabric. Alternatively, the abrasive particles could be applied, for example, to the surface of a molten binder or a sticky binder by application of heat. The abrasive particles can be characterized as hard abrasive particles, soft inorganic abrasives, and plastic abrasives. Conventional hard abrasive particles include aluminum oxide; carbides, borides, and metallic nitrides; molten zirconia alumina; and abrasive sol gel particles, as well as minerals such as diamond and garnet. Conventional soft inorganic particles include silica, iron oxide, chromia, ceria, zirconia, titania, silicates and tin oxide as well as metal carbonates, metal sulfides, aluminum trihydrate, graphite, and metal particles. The plastic abrasive particles can be formed of thermoplastic materials as well as heat setting materials such as polyvinyl chloride, or melamine formaldehyde resin, respectively. The non-woven fabric can be coated with a mixture of two or more different abrasive particles. The abrasive particle can be treated to improve the adhesion between the abrasive particle and the binder.

The non-woven fabrics may additionally comprise additives such as surface modifying additives, curing agents, splicing agents, plasticizers, fillers, blowing agents, fibers, antistatic agents, initiators, suspending agents, photosensitizers, lubricants, wetting agents, surfactants, pigments, dyes, UV stabilizers and suspending agents. These materials may be useful depending on the presence of a binder in the non-woven fabric and / or depending on the use of the fabric. Those skilled in the art will appreciate that non-woven articles can be made in various configurations and constructions and using any of a variety of materials and ingredients. In general, the method of the invention is capable of treating all those modalities.

A nonwoven article for use as a substrate in the practice of the invention is that described in US Patent No. 5,282,900 (McDonell, et al.). The article comprises a high, three-dimensional open fabric comprising numerous thermoplastic organic fibers, a binder that adheres the fibers at points of mutual contact, and abrasive particles bonded to the fibers by the binder. The abrasive particles have a size between a range of about 0.1 to about 30 microns.

Another preferred substrate for use in the method of the present invention is a non-woven fabric comprising hydrophilic fibers and a binder comprising a crosslinked polyvinyl alcohol (PVA). Such a substrate is described in U.S. Patent No. 5,641,563 (Truong et al.). Preferred hydrophilic fibers include the following types of fibers: cellulosic type fibers such as PVA (including hydrolyzed vinyl ester copolymers, particularly hydrolyzed vinyl acetate copolymers), cotton, viscose rayon, cupramonium rayon, and the like; as well as thermoplastics such as polyesters, polypropylene, polyethylene, nylons and similars. Preferred cellulosic fibers for absorbent cleaning articles are rayon and polyvinyl alcohol (PVA) which are commercially available as basic fibers.

Other useful substrates include spun yarns and fabrics as well as sponge fabrics. Synthetic sponges are typically comprised of viscose cellulose, and may also contain reinforcing fibers. The viscose cellulose can be made from any conventional viscose technique. Viscose cellulose is commonly prepared by mercerizing and debranching wood pulp, followed by carbon disulfide xantation., dilution with water, and finally, mixing of the mixture. After the viscose cellulose is made, crystals of sodium sulphate decahydrate referred to as Glauber's Salts are added to the viscose cellulose. Subsequently reinforcing fibers or other additives are added. The resulting mixture is heated to approximately 100 ° C, causing the cellulose to coagulate while the sodium sulfate is melted. The sodium sulfate is rinsed from the resulting regenerated sponge leaving a porous structure. Spun and woven materials include, for example, bath towels, dish cloths and the like.

Preparation procedure In the following examples, the following preparation procedure was employed.

Procedure A - Ion / Polymer Solution 10 grams of glacial acetic acid were added to 480 grams of water and placed under a mixer. 10 grams of Chitosan (obtained from Vanson Chemical Company of Redmond, Washington) was weighed and added to the stirred acetic acid solution with suitable stirring until the polymer dissolved. A solution of zinc acetate was prepared by dissolving 10 grams of zinc acetate dihydrate (Aldrich Chemical Company) in 490 grams of water. Subsequently, chitosan and zinc acetate solutions were blended under continuous mixing to provide an ion / polymer solution suitable for the manufacture of antimicrobial articles.

In some examples, cupric sulfate pentahydrate or iron (II) heptahydrate sulfate (both from Aldrich Chemical Companies, Milwaukee, Wisconsin) was replaced by zinc acetate dihydrate in the ion / polymer solution formulation. In all other respects, the ion / polymer solutions comprising iron or copper ions were made identical to the zinc solution. The weight percentage of zinc used in the ion / polymer mixture was 0.298% by weight (1% zinc acetate dihydrate). An equivalent amount of iron (II) sulphate heptahydrate in 1 liter of ion / polymer solution was 14.82 grams (0.198% Fe). Similarly, an equivalent amount of cupric sulfate pentahydrate was 11.70 grams in 1 liter of ion / polymer solution, providing 0.298% copper in the solution.

Method B - Antimicrobial Solution A commercially available solution of sodium pyrithione (Olin Chemical Company, Stanford, Connecticut), 40% by weight was diluted to obtain a pritiona concentration of 3000 ppm by adding 7.5 grams of the commercial solution in 1992.5 grams of water. This resulting solution was stirred vigorously.

Procedure C - Substrate Treatment The substrates were soaked in the Ion / Polymer solution, for about one minute, they were removed and squeezed using a clear zero squeezing machine. The coated substrates were placed in an oven maintained at about 113 ° C (235 ° C) until completely dried. The substrates treated and dried in this manner were immersed in the Antimicrobial Solution pyrithione for one hour. After one hour of submersion, excess unreacted pyrithione was removed from the substrates by soaking each substrate in water and passed through a zero-clear extruder. The rinsing and subsequent squeezing of each substrate was repeated 10 times. The rinsed substrates were dried in an oven overnight at 60 ° C and tested to determine the retained pyrithione by reacting the pyrithione with an iron chloride reagent and analyzing the substrate by absorption spectrometry (Beckman Spectrophotometer DU 640 purchased from through Beckman Instruments Inc. in Fullerton, California).

Test Methods and Materials The articles made in the following examples were evaluated according to the following methodology.

Test to kill Bacteria Substrates were tested for antimicrobial activity by measuring their effectiveness against certain bacteria. The tested substrates were subjected to a water rinse protocol to allow an evaluation of the durability of the antimicrobial treatment for the substrate. The rinse protocol consisted of the saturation of the substrate in tap tap water maintained at about 130 ° F (54 ° C) and then the saturated substrate was squeezed, repeating the rinse / squeeze cycle as much as 400 times per sample. Before performing the death test, some samples were autoclaved for 30 minutes at 121 ° C to reduce possible bacterial contamination introduced by the rinse protocol. Substrate samples prepared in this manner were placed in sterilized sample bags (available under the trade designation of "Tekmar" from VWR Scientific of Philadelphia, Pennsylvania) for a bacteria test.

A mass inoculum containing approximately 1 X 106 colony forming units (cfu) / ml was prepared in peptone water using the subspecies of salmonella choleraesuis tiphimurium serotype choleraesuis (ATCC 14028). Each substrate sample was inoculated with 20 ml of the mass suspension and placed in a Stomacher Model 80 Laboratory Mixer (available from VWR Scientific of Philadelphia, Pa.) For two minutes at high speed (260 rpm) to distribute the organisms through the substrate. Viable organisms were enumerated by removing 1 ml of solution from the sample bag and performing a 10-fold serial dilution in peptone water. One ml of each test tube used in the serial dilution, together with 1 ml of sample from the sterile sample bag, was placed on a plate using a tripticase soy mucilage broth (TSBA). The plates were incubated for two to three days at 28 ° C and their microbial growth was subsequently examined. Each of the substrates was sampled after inoculation and 1 day, 3 days, and 7 days after inoculation. A separate set of substrates as above was also tested, using a mixed suspension of Pseudomonas chloraphis (CRL ID # 3357) and Pseudomonas putida (CRL ID # 3352).

Fungus Susceptibility Test The substrates were prepared as in the Test for the Bacterial death beginning with the rinsing stage that is described there r. The substrates were tested in accordance with the ASTM G21-90 test method by applying in aerosol form a spore suspension of mixed fungi of known concentration on the surface and incubating the material at 28 ° C / 95% Relative humidity during 28 days. Samples are placed with asepsis on the surface of a mucilage plate of minimal salts (M-9) and inoculated. The medium used does not contain a source of carbon. Therefore, the growth of fungi indicated a breakdown of the components of the sample. The standard test uses five organisms: Aspergillus niger (ATCC 9642), Penicillium virens (ATCC 11797), Chaetomium globosum (ATCC 6205), Gliocladium virens (ATCC 9645) and Aureobasidium pullulans (ATCC 15233). In addition, a separate set of samples was prepared as in the previous case and inoculated using a Penicillium species characterized in part by its apparent immunity to the chitosan-zinc-pyrithione complex. The samples were examined daily to determine the presence of fungal growth and the growth level was typified at certain intervals, as indicated herein. A piece of sterile filter paper served as a positive control.

EXAMPLES The following non-limiting examples further illustrate aspects of the invention. Unless otherwise indicated, all parts and percentages are by weight.

Example 1 Commercially available non-woven cloths were prepared under the trade designation "Cloth O-Cel-0 All Purpose" from Minnesota Mining Manufacturing Company, St. Paul Minnesota in accordance with the Preparation Procedures AC using zinc / chitosan as the solution of ion / polymer and pyrithione as the antimicrobial.

Example 2 Antimicrobial articles were prepared using sponge cloth which is commercially available from Kalle Nalo GmbH of Wiesbaden, Germany. The articles were prepared according to the AC Preparation Procedures described above except that the ion / polymer solution was prepared to include 0.6% by weight of zinc acetate dihydrate and 0.6% by weight of chitosan together with 1.0% of 3- ( trimethoxysyl) propyl glycidyl ether (commercially available under the trade designation "A-187" from OSi Specialties Inc., Danbury, Connecticut).

Example 3 Antimicrobial articles were prepared using sponge cloth which is commercially available from Kalle Nalo GmbH of Wiesbaden, Germany. The articles were prepared in accordance with the AC Preparation Procedures described above except that the Ion / Polymer Solution was 1.0% polyethyleneimine (PEI) (available from Hoechst Celanese of Portsmouth, VA under the trade designation "Corcat P-12. ") as the cleaning polymer with 1% zinc and 1.0% 3- (trimethoxysyl) propylglycidyl ether. The substrates were tested with sodium pyrithione solution at a concentration of 1000 ppm in 1 liter.

Example 4 Antimicrobial articles were prepared using as a substrate a sponge cloth available from Spontex Company (Columbia, Tennessee). The substrates were treated as in Example 2 except that the Ion / Polymer Solution was 0.5% by weight for each of the components.

Example 5 Commercially available cellulose sponges from Minnesota Mining and Manufacturing Company, St Paul Minnesota under the trade designation "Niagara" were treated as in Example 2 except that the weight percent of chitosan and zinc acetate dihydrate in the Solution of Ion / Polymer was 0.5%.

Example 6 Cellulose sponges ("Niagara" sponges of Minnesota Mining and Manufacturing Company, St. Paul Minnesota) were treated as in Example 5 except that the Ion / Polymer solution included 0.5% of 3- (trimethoxysyl) propyl glycidyl ether.

Example 7 A series of substrates were treated according to the above Preparation Procedure A-C to illustrate the variety of possible substrates that can be treated by the antimicrobial treatment of the invention. The treated substrates were: (1) Polyurethane sponges, from Dayton Hudson Corporation, Minneapolis, Minnesota; (2) Plush Towels, also from Dayton Hudson Corporation; (3) Vegetable Sponge, available under the commercial designation of "L'Esprit", Sunny Marketing Systems Incorporated, Port Washington, New York; (4) Wipes available under the trade designation "Handi Scrub Cloth", Kimberly-Clark, Neenah, WI; and (5) a fiber containing cloth commercially available under the trade designation "3M High Performance Cloth" from Minnesota Mining and Manufacturing Company, St. Paul Minnesota.

Example 8 Cellulose sponges were treated in accordance with Preparation Procedures A-C using on as the chelating ion in the Ion / Polymer Solution. The sponges treated in this way turned black due to the reaction of copper with sodium pyrithione.

Example 9 The cellulose sponges were treated according to Preparation Procedures A-C using iron as the chelating ion in the Ion / Polymer Solution. The sponges treated in this way turned black due to the reaction of iron with sodium pyrithione.

Comparative Example A The untreated sponge fabric obtained commercially from Kalle Nalo GmbH of Wiesbaden, Germany was used as a comparative example in the antimicrobial tests that were established here.

Comparative Example B The untreated sponge fabric obtained from Spontex Company of Columbia, Tennessee was used as a control for the comparative tests set forth herein.

Comparative Example C A commercially available non-woven cleaning cloth product available from Colgate-Palmolive Company under the trade designation "Handi Wipe" was used as a control in the comparative tests set forth herein.

Comparative Example D A nonwoven cleaning cloth product obtained from Novapharm Research (Australia) Pty Ltd. was used as a control. This cleaning cloth product was purchased as an antimicrobial and is believed to include zinc pyrithione as an antimicrobial agent.

Examples 2 and 4 and Comparative Examples A and B The articles made according to Examples 2 and 3 were tested by the Bacterial Death Test and the Fungal Susceptibility Test described above. The data for the Test for the Death of Bacteria is presented in Tables 1 and 2, for the Salmonella and Pseudomonas organisms, respectively. The Data for the Pseudomonas are presented in Table 2.

The results of the Mushroom Susceptibility Test are shown in Table 3.

Additionally, the samples were treated with a Penicillin strain normally immune to the antimicrobial effects of the zinc-pyrithione complex. This was conducted as a control, hoping that the Penicillium test could show failures for all the samples tested, including the samples prepared according to the invention. The results of the fungus susceptibility test with Penicillium are presented in Table 4.

Example 1 and Comparative Example C and D The articles made according to Example 1 were tested according to the Bacterial Death Test and the Mushroom Susceptibility Test and compared with articles of Comparative Examples C and D. Bacterial death were conducted for Salmonella and the data are presented in the Table and in Table 6.

The two data sets (Tables 5 and 6) were collected because it is believed that some of the initial data collected first for Comparative Example D (samples OX and 10X) were erroneous.

A separate Bacterial Death Test for Staphylococcus Aureus (ATCC 6538) was conducted as a control. This data is presented in Table 7.

The data for the Mushroom Susceptibility Test is presented in Table 8 for standard organisms ASTM G21-90. Table 9 includes data on the Mushroom Susceptibility Test for articles treated with Penicillium. Zinc pyrithione is known to be relatively ineffective against fungal species, and the data in Table 9 were collected as a control.

TABLE 1 Bacterial Death Test (Salmonella) "X" indicates the number of times the substrate was soaked and squeezed before being tested. It is believed that there was contamination present in these samples.

TABLE 2 Bacterial Death Test (Pseudomonas) One or two samples failed before the other. 2. "X" indicates the number of times the substrate was soaked and squeezed before being tested.

TABLE 3 X "indicates the number of times the substrate was soaked and squeezed before being tested 0 = No growth was observed 1 = Growth traces, 1 to 10% coverage of the sample surface due to mildew 2 = Light growth, 10 to 30% coverage of the sample surface by mold 3 = Moderate growth, 30 to 60% coverage of the sample surface by mold 4 = Strong Growth.> 60% surface coverage the sample by mold.

TABLE 4 Fungus Susceptibility Test (ASTM 621-90 and Penicillium) X "indicates the number of times the substrate was soaked and squeezed before being tested 0 = No growth was observed 1 = Growth traces, 1 to 10% coverage of the sample surface due to mildew 2 = Light growth, 10 to 30% coverage of the sample surface by mold 3 = Moderate growth, 30 to 60% coverage of the sample surface by mold 4 = Strong Growth.> 60% surface coverage the sample by mold.

TABLE 5 Bacteria Death Test (Salmonella) "X" indicates the number of times the substrate was soaked and squeezed before being tested. 2 The lowest dilutions of these two samples were not placed on the plates. The lowest dilution placed on a plate was 1: 100 and no organisms were recovered, so that these two samples actually showed a log reduction of > 4.5 / 4.6.

TABLE 6 Bacteria Death Test (Salmonella) 1. "X" indicates the number of times the substrate was soaked and squeezed before being tested.

TABLE 7 Bacterial Death Test (Staphylococcus Aureus) W v X "" indicates the number of times the substrate was soaked and squeezed before being tested.

TABLE 8 Fungus Susceptibility Test (ASTM 621-90) X "indicates the number of times the substrate was soaked and squeezed before being tested 2, 0 = No growth was observed 1 = Growth traces, 1 to 10% coverage of the sample surface by mold. light, 10 to 30% coverage of the sample surface due to mold, 3 = moderate growth, 30 to 60% coverage of the sample surface due to mold, 4 = strong growth,> 60% coverage of the surface of the sample by mold.

TABLE 9 Fungus Susceptibility Test (Penicillium) X "indicates the number of times the substrate was soaked and squeezed before being tested 2 0 = No growth was observed 1 = Growth traces, 1 to 10% coverage of the sample surface due to mold 2 = Light growth , 10 to 30% coverage of the sample surface by mold, 3 = Moderate growth, 30 to 60% coverage of the sample surface by mold, 4 = Strong Growth,> 60% surface coverage. of the sample by mold.

EXAMPLES 10 - 16 Non-woven cloths were prepared from non-woven, carded, cross-lapped, and punched fabrics composed of 20% rayon fibers (fibers type "18552", 1.5 denier x 51 mm, Courtalds Chemical Company, England) and 80% poly (vinyl alcohol) fibers (fiber type "VPB 202", 2.0 denier x 51 mm, Kuraray KK, Japan) with a basis weight of 158 g / m2 and a thickness of 2.3 mm.

A coating solution was prepared to contain 45.5 g of a 10% aqueous solution of poly (vinyl alcohol) ("R1130" from Kuraray KK, Japan), 2.25 g of linkers ("Tyzor 131" from DuPont Company, Wilmington, DE), 0.22 g colloidal silica ("Nalco 8676" from Nalco Chemical Company, Naperville, IL), 1.0 g of RED BRYN 6002 Orcobrite pigment (Organic Dyestuffs Corporation, Concord, NC), and 154 g of deionized water.

A solution of Ion / Polymer was prepared by dissolving 15 g of 60 mesh chitosan (Vanson, Redmond, WA) in a 5% solution of glacial acetic acid, followed by a reaction, without gelation, of chitosan with an excess of zinc acetate. (Aldrich Chemical Company, Mil Akee, WI). A measured amount of this zinc-chitosan solution was added to the above solution in order to achieve the desired levels of chitosan in the dried resin.

A 30.5 cm by 38.1 cm piece of combined nonwoven fabric was coated with the coating solution, dried at 162.7 ° C for fifteen (15) minutes. Upon completion of curing, the sample was soaked by hand and reacted with a 10% solution of sodium pyrithione for thirty (30) minutes. The articles were subjected to a final manual rinse using lukewarm running water. The articles of Examples 11, 13 and 15 were subjected to a final rinse by immersing the articles for 3 hours in water maintained at approximately 66 ° C. After the final rinse, each of the items was tested for pyrithione retention and for antimicrobial (antihongo) efficacy according to the Fungal Susceptibility Test. The data for this test are reported below in Table 10 along with a description for each of the cloths made in accordance with the procedure described. The description includes an indication of the level of chitosan in the dried resin.

Comparative Examples E-H Additional articles were prepared for use as in Examples 10-15 except that the fabrics were not treated with sodium pyrithione. Comparative Example E was prepared to comprise 0.7% by weight of chitosan, Comparative Example F was prepared to comprise 1.8% by weight of chitosan. Comparative Example F was prepared without the addition of chitosan in the cover solution, but manually applied chitosan powder to the finished article. The data of the Test are presented in Table 10.

Example 17-25 The acrylic latex-based cloths were prepared for Examples 17-23 and Example 25 from a non-woven, carded, cross-lapped, punched cloth comprising 20% rayon fibers (18552, 1.5 denier x 51 mm, Courtalds Chemical Company, England) and 80% poly (vinyl alcohol) fibers (VPB 202, denier x 51 mm, Kurray KK, Japan) with a basis weight of 158 g / m2 and a thickness of 2.3 mm.

A coating solution was prepared containing 4.8 g of a 55.4% aqueous dispersion of styrenated acrylic latex ("T278", BF Goodrich Company, Cleveland, Ohio, OH), 0.52 g of linker ("Primid XL-552" from Rohm and Haas Company, Philadelphia, PA). 0.25 g of Orcobrite RED BRYN 6002 pigment (Organic Dyestuffs Corporation, Concord, NC), and 29.6 g of deionized water.

An ion / polymer solution was prepared by dissolving 15 g of 60 mesh chitosan (Vanson, Redmond, WA) in a 5% solution of glacial acetic acid, followed by the reaction, without gelation, of the chitosan with an excess of zinc acetate. (Aldrich Chemical Company, Milwaukee, WI). A measured amount of 5% zinc solution was added to the above cover solution to obtain the desired chitosan level in the dry resin of the finished article.

A 19 cm by 21 cm piece of a nonwoven fabric combined with a cover solution was manually coated, dried at 65.5 ° C, and cured at 107.2 ° C for fifteen (15) minutes. After curing was complete, the sample was soaked and reacted with a 10% solution of sodium pyrithione for thirty (30) minutes. When applying a final soak, immediately some of the cloths were tested to determine the retention of pyrithione and the antimicrobial efficacy (antihongo) according to the Fungal Susceptibility Test.

The article of Example 24 was a PVA-based cloth according to the general procedure of Examples 10-16, treated with zinc-chitosan-pyrithione and having a chitosan concentration in the dry coverage of 1.5% by weight.

Comparative Examples I-L Article was prepared for use as Comparative Examples. The articles of Examples I and J were prepared as in Examples 17-23 and 25. The articles of Comparative Examples K and L were prepared as in Examples 10-16. Some of the articles were treated with zinc-chitosan added in the coverage solution without a subsequent treatment of pyrithione. Other items were made without zinc-chitosan in the cover solution and then treated by manual application of a specific amount of dry chitosan powder. A description of the article and test data for the Fungus Susceptibility Test is presented in Table 11.

Examples 26 and 27 Hand sponges were prepared by dipping coverage of commercially available nonwoven scrubbing or scrubbing products. In Example 26 was a "Scotch-Brite" LP-96 hand sponge available from Minnesota Mining and Manufacturing Company, St. Paul Minnesota and in Example 27 was a "Scotch-Brite" LP-98 hand sponge, also available of Minnesota Mining and Manufacturing Company. The sponges were treated with a zinc-chitosan solution, prepared as described in Example 17. The excess solution was removed using a mechanical juicer. The article was then treated at 120 ° F and placed in a plastic bag with approximately 250 ml of a sodium pyrithione solution of 2000 ppm. The article was allowed to react for thirty (30) minutes at room temperature. At the end of thirty minutes, the article was rinsed with tap water and dried again at 120 ° F for several hours before being tested for pyrithione retention and microbiological efficacy.

These samples were evaluated for antihongo efficacy according to the ASTM G21-90 standard test procedure for twenty-eight (28) days. Both Examples 27 and 28 were evaluated with repeated ratings of 1.5 for Example 27 and repeated ratings of 1.0 for Example 28. A rating of 1 indicated a trace growth, with 1-10% of the sample surface showing some growth mushroom. A rating of 2 indicated a slight growth and 10-30% coverage of the sample.

Examples 10-16 and Comparative Examples E-H The article made according to Examples 10 -16 and Comparative Examples E-H were tested according to the Mushroom Susceptibility Test using the organisms of ASTM G21-90. The data was collected by for the samples repeated 28 days after inoculation with the test organisms. The data are presented in Table 10.

TABLE 10 Results of the Mushroom Susceptibility Test The data show that incorporation of the zinc-chitosan-pyrithione complex into a resin formulation of a cleaning cloth provides excellent protection against fungal growth. It is believed that Chitosan alone (for example, without pyrithione) is an insufficient protection against the growth of fungi. The good results of Comparative Example H are inconsistent with other data for samples treated with chitosan but without pyrithione. The inventive process provides a cleaning cloth with an antimicrobial treatment with sufficient durability to withstand manual rinsing.

Examples 17-25 and Comparative Examples I-L Articles made according to Examples 17-25 and Comparative Examples I-L were tested using the Fungal Susceptibility Test with organisms required by the ASTM standard test procedure G21-90. . The data was recovered in duplicate after 28 days of inoculation with the test organisms.

The articles of Examples 21-25 and Comparative Examples K and L were first subjected to a washing cycle in a washing machine with rinse temperatures in the range of 40 ° C to 95 ° C. These items were washed in a commercially available washing machine (available under the trade designation of "ASKO 20004" from ASKO USA, Inc. of Richardson, Texas), a front loading unit capable of washing clothes with water temperatures of 20 °. C at 95 ° C.

Fungal Susceptibility tests were conducted for these items after washing. The test data is presented in Table 11 together with the descriptive information for each of these tested items, including the level of chitosan in the dried resin.

Table 11 Results of the Mushroom Susceptibility Test The above results show that articles made in accordance with the present invention possess good protection against the growth of fungi. The Fungus Susceptibility Test data shows that zinc-chitosan alone does not provide sufficient protection against fungal growth. Additionally, the inventive method provides articles with an antimicrobial treatment durable enough to withstand the rinsing / washing cycles at moderate temperatures (e.g., 40 ° C). However, the durability of articles subjected to a rinsing at extreme temperatures (e.g., 60-95 ° C, was poor.

While the foregoing description describes the preferred embodiment of the invention, those skilled in the art will be able to make changes and modifications of the described embodiment without departing from the true essence and scope of the invention, as set forth in the appended claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (17)

1. CLAIMS A method for making an antimicrobial article, characterized in that it comprises: the formation of a solution comprising a chelating polymer and a metal ion; the deposition of the solution in the substrate; drying the substrate to form a coated substrate; and the addition of an enhancer to the coated substrate to form an antimicrobial article. The method according to claim 1, characterized in that the formation of a solution comprising a chelating polymer and a metal ion comprises: (A) the selection of a chelating polymer from the group consisting of polyglucosamines, copolymers of ethylene acrylic acid, acids polycarboxylics, and polyamines, (B) the solution of the chelating polymer in acid to form an acid solution, (C) the preparation of an aqueous solution of the metal ion, and (D) the combination of the aqueous solution of the metal ion and the solution acid. The method according to claim 2, characterized in that the polyglucosamine is chitosan. The method according to claim 2, characterized in that the preparation of an aqueous solution of the metal ion comprises the selection of a salt of the metal ion and the dissolution of the salt in water. The method according to claim 4, characterized in that the metal ion is selected from the group consisting of zinc, zirconium, iron and copper. The method according to claim 1, characterized in that the solution is deposited on the substrate by immersing the substrate in the solution and draining the excess solution from the substrate after immersion. The method according to claim 1, characterized in that the substrate is dried in an oven at a temperature in the range between 105 ° C and 120 ° C. The method according to claim 1, characterized in that the addition of an enhancer to the coated substrate is achieved by dissolving the enhancer in water to provide an enhancer solution, treating the coated substrate with the enhancer solution, drying the substrate to provide an article. Antimicrobial finished. The method according to claim 1, characterized in that the enhancer is selected from the group consisting of alkyl dithiocarbamates, thiazoles, imidazoles, pyrithione or mixtures thereof. A method for the treatment of a substrate to provide an antimicrobial article, characterized in that it comprises: the deposition of a solution to the substrate to form a coated substrate, the solution comprising a chelating polymer and a metal ion: the drying of the coated substrate; the addition of an enhancer to the dry coated substrate to form the antimicrobial article. The method according to claim 10, characterized in that it additionally comprises the formation of the solution comprising a chelating polymer and a metal ion by (A) the selection of a chelating polymer from the group consisting of polyglucosamines, copolymers of ethylene acrylic acid, polycarboxylic acids, and polyamines, (B) the solution of the chelating polymer in acid to form an acid solution, (C) the preparation of an aqueous solution of the metal ion, and (D) the combination of the aqueous solution of the metal ion and the acid solution.
2. 12. The method according to claim 11, characterized in that the polyglucosamine is chitosan.
3. 13. The method according to claim 11, characterized in that the preparation of an aqueous solution of the metal ion comprises the selection of a salt of the metal ion and the dissolution of the salt in water.
4. 14. The method according to claim 13, characterized in that the metal ion is selected from the group consisting of zinc, zirconium, iron and copper.
5. 15. The method according to claim 10, characterized in that the solution is deposited on the substrate by immersing the substrate in the solution and draining the excess solution from the substrate after immersion.
6. 16. The method according to Claim 10, characterized in that the substrate is dried in an oven at a temperature in the range between 105 ° C and 120 ° C.
7. 17. The method according to claim 10, characterized in that the addition of an enhancer to the coated substrate is achieved by dissolving the enhancer in water to provide an enhancer solution, treating the coated substrate with the enhancer solution, drying the substrate to provide an article. Antimicrobial finished.
8. 8. The method according to claim 10, characterized in that the enhancer is selected from the group consisting of alkyl dithiocarbamates, thiazoles, imidazoles, pyrithione or their mixtures. SUMMARY OF THE INVENTION A method for making an antimicrobial article, said method comprising; the provision of a substrate; the formation of a solution comprising a chelating polymer and a metal ion; the deposition of the solution in the substrate; drying the substrate to form a coated substrate; and the addition of an enhancer to the coated substrate to form the antimicrobial article. The formation of the solution includes: (A) the selection of a chelating polymer from the group consisting of polyglucosamines, copolymers of ethylene acrylic acid, polycarboxylic acids, and polyamines, (B) the dissolution of the chelating polymer in acid to form an acid solution, (C) the preparation of an aqueous solution of the metal ion, preferably by the selection of a salt of the metal ion and the dissolution of the salt in water, and (D) the combination of the aqueous solution of the metal ion in the acid solution. The addition of the enhancer to the coated substrate is achieved by dissolving the enhancer in water to provide an enhancer solution, treating the coated substrate with the enhancer solution, drying the substrate to provide the finished antimicrobial article. The invention provides a method for treating a variety of substrates to thereby provide the substrate with resistance to certain microbial growth.