Patent Description:
Numerous biocides exist for incorporation into coating compositions, resin moldings, paper binders, and other polymeric materials to impart antimicrobial performance. Two major classes of actives are organic (e.g. quaternary ammonium silanes) and inorganic (e.g. copper, silver, etc). Of the inorganic actives used most commonly is silver, or most specifically silver ion. Typical carriers are silver nanoparticles, silver salts, ion exchange resins, and glass.

Compositions containing the inorganic antimicrobials, specifically silver ions, are known to exhibit instabilities leading to discoloration upon exposure to heat, moisture and/or sun light. Discoloration has been previously discussed in <CIT> and <CIT>. These inorganic biocides frequently produce color on lightly colored or white fabric making them less desirable. Accordingly, the use of these compositions is effectively limited to systems for which such conspicuous changes in coloration can be tolerated.

One method for inhibiting silver-related discoloration is provided by <CIT>. Ohsumi et al. discloses the combination of an inorganic compound on which silver ions are supported with benzotriazole.

Another method for inhibiting discoloration is described by <CIT>. Ghosh et al. discloses a copolymer composing of a heterocyclic containing monomer which is said to complex with silver ions. The composition is light stable in the wet formulation. However, the color stability performance on the fabric, especially on nylon and polyester fabric, is not addressed. Surprisingly, an unacceptable color change was found for the treated fabric even under the upper limit of VI monomer to silver ion molar ratio disclosed in <CIT>. The upper limit molar ratio disclosed is <NUM>:<NUM> based on the upper limit weight ratio of <NUM>:<NUM> of VI to silver ion.

<CIT> discloses a composition useful for treating fabrics. The composition contains a silver-containing copolymer having polymerized units of a monomer X and a monomer Y; wherein monomer X is an ethylenically unsaturated compound having a substituent group selected from an unsaturated or aromatic heterocyclic group having at least one hetero atom selected from N, O and S; wherein monomer Y is selected from carboxylic acids, carboxylic acid salts, carboxylic acid esters, organosulfuric acids, organosulfuric acid salts, sulfonic acids, sulfonic acid salts, phosphonic acids, phosphonic acid salts, vinyl esters, (meth)acrylamides, C<NUM>-C<NUM> aromatic monomers containing at least one exocyclic ethylenic unsaturation and combinations thereof. <CIT> discloses an aqueous composition useful for treating fabric comprising (i) a complex of silver ion with a copolymer and (ii) a dispersed amine-functional softener, wherein said copolymer comprises (a) <NUM>-<NUM> wt % polymerized units of one or more monomer X, wherein said monomer X is an ethylenically unsaturated compound having a substituent group selected from an unsaturated or aromatic heterocyclic group having at least one nitrogen atom; and (b) <NUM>-<NUM> wt % polymerized units of one or more monomer Y, wherein said monomer Y is an ethylenically unsaturated compound selected from carboxylic acids, organosulfuric acids, sulfonic acids, phosphonic acids, esters comprising polymerized units of ethylene oxide, and mixtures thereof.

Nevertheless, there remains a need for new compositions which exhibit the positive antibacterial activity of metal ions without influencing fabric hand/feel or color appearance which can result from undesirable light stability problems due to the metal (e.g. silver) and/or to the color of organic additives (e.g. polymers), especially across fabric compositions of cotton, polyester, nylon, and combinations thereof.

The present invention provides a transition metal-polymer complex treated article comprising:.

further wherein the molar ratio of monomer X to transition metal is from <NUM>:<NUM> to <NUM>:<NUM>.

The invention further provides a method for treating a fiber or fabric comprising:.

The present invention still further solves the problem in the art by providing a treated article comprising a fiber or fabric comprising at least one silver ion-polymer complex; comprising a monomer X selected from the group consisting of vinylimidazole, vinylimidazoline, vinylpyridine, vinylpyrrole, derivatives thereof and combinations thereof; and a transition metal, wherein the transition metal is silver; further wherein the molar ratio of monomer X to transition metal is from <NUM>:<NUM> to <NUM>:<NUM>. The present invention also provides a method for making the same.

As used herein and in the appended claims, "fabric" means a woven or nonwoven textile such as cotton, polyester, nylon, lycra, polyolefin and blends thereof.

As used herein and in the appended claims, "fiber" refers to a unit of matter which is capable of being spun into a yarn or made into a fabric by bonding or by interlacing in a variety of ways including, for example, weaving, knitting, braiding, felting, twisting or webbing.

The term "yarn" as used herein refers to a strand of textile fiber in a form suitable for weaving, knitting, braiding, felting, twisting, webbing, or otherwise fabricating into a fabric.

As used herein and in the appended claims, the term "silver" refers to silver metal that is incorporated into an antimicrobial composition of the present invention. While not wanting to be bound as to the oxidation state of the silver (Ag <NUM>, Ag <NUM>+ or Ag <NUM>+) that is incorporated into the antimicrobial composition, silver may be added to the antimicrobial composition by washing the polymer in a silver solution such as silver nitrate in deionized water ("DI"). Aside from DI, other liquid mediums can also be used such as water, aqueous buffered solutions and aqueous/organic solutions made with water miscible organics such as solvents such as alcohols, surfactants and softeners. Other sources of silver include but are not limited to silver acetate, silver citrate, silver chloride, silver iodide, silver lactate, silver picrate, silver oxide, and silver sulfate. The concentration of silver in these solutions can vary from the concentration required to add a known quantity of silver to the antimicrobial composition to a saturated silver solution.

The use of the term "(meth)" followed by another term such as acrylic, acrylate, acrylamide, etc., as used herein and in the appended claims, refers to, for example, both acrylic and (meth) acrylic; acrylate and methacrylate; acrylamide and methacrylamide; etc. Additionally any acids described in the reference herein also include the salt form and vice versa.

All percentages expressed herein are wt. % or ppm w/w. All range endpoints are inclusive and combinable.

According to the present invention there is provided a fabric comprising at least one transition metal polymer complex comprising at least one polymer and a transition metal.

The polymer of the present invention may suitably be a polymer comprising a) <NUM>-<NUM> wt % polymerized units of a monomer X; and (b) <NUM>-<NUM> wt % polymerized units of a monomer Y which is an ethylenically unsaturated compound.

Monomer X of the present invention is selected from the group consisting of vinylimidazole, vinylimidazoline, vinylpyridine, vinylpyrrole, derivatives thereof and combinations thereof. Preferably, monomer X is N-vinylimidazole.

In some embodiments of the present invention, monomer Y is selected from carboxylic acids, organosulfuric acids, sulfonic acids, phosphonic acids and esters of polymerized units of ethylene oxide and combinations thereof. In some embodiments of the invention, esters comprising polymerized units of ethylene oxide comprise at least <NUM> units of ethylene oxide, alternatively at least <NUM>, alternatively at least <NUM>, alternatively at least <NUM>, alternatively at least <NUM>. The number of polymerized ethylene oxide units is calculated from the Mn of the polymerized ethylene oxide chain. In some embodiments of the invention, the esters of polymerized units of ethylene oxide are (meth) acryloyl esters. In some embodiments of the invention, polymerized units of ethylene oxide may be capped with a C<NUM>-C<NUM> alkyl group on one end. In some embodiments of the invention, polymerized units of ethylene oxide have Mn from <NUM> to <NUM>. In some embodiments of the invention, the polymerized units of ethylene oxide have Mn from <NUM> to <NUM>, alternatively from <NUM> to <NUM>, alternatively from <NUM> to <NUM>.

In some embodiments of the invention, monomer Y is selected from acrylic acid (AA), methacrylic acid (MAA), itaconic acid, maleic acid, fumaric acid, <NUM>-acrylamido-<NUM>-methylpropanesulfonic acid and its sodium salt and combinations thereof. In some aspects of these embodiments, the copolymer further comprises other ethylenically unsaturated monomers, e.g., (meth) acrylate esters, vinyl esters, (meth) acrylamides. Small amounts of hydrophobic monomers, e.g., higher alkyl (meth) acrylates (e.g., C-<NUM> and higher), may be present to the extent they do not compromise water solubility. (Meth)acrylate esters may include esters of mixed ethylene/propylene oxides, providing that ethylene oxide residues are at least <NUM> wt % of the ethylene/propylene oxide residues (alternatively at least <NUM>%, alternatively at least <NUM>%) or that the esters of mixed ethylene/propylene oxide residues are no more than <NUM> wt% of the copolymer, alternatively no more than <NUM>%, alternatively no more than <NUM>%. In some embodiments of the invention, mixed ethylene/propylene oxide residues have Mn of at least <NUM>, alternatively at least <NUM>.

Alternatively, more than one polymer may be combined in the polymer complex of the present invention. Suitably, a second polymer may be a polymer comprising: (a) polymerized units of the monomer X; and (b) polymerized units of monomer Z wherein monomer Z is a non-heterocyclic saturated compound selected from acrylic acid, (meth) acrylic acid, ethyl acrylate, and butyl acrylate and combinations thereof. The polymer comprises X and Z in a ratio of <NUM>:<NUM> to <NUM>:<NUM>; alternatively <NUM>:<NUM> to <NUM>:<NUM>; alternatively <NUM>:<NUM> to <NUM>:<NUM>. Butyl acrylate is present in the copolymer in the amount from <NUM>% to <NUM>%, alternatively from <NUM>% to <NUM>%, and further alternatively from <NUM>% to <NUM>%. Acrylic acid is present in the copolymer in the amount from <NUM>% to <NUM>%, alternatively <NUM>% to <NUM>%, alternatively <NUM>% to <NUM>%.

According to the present invention the first and second polymers may be present independently, may be present together, and present with or without additional polymers.

At least one transition metal combines with at least one polymer to form a transition metal polymer complex. The transition metal is silver. Silver may be present on the fiber or fabric at a silver concentration of <NUM>-<NUM> ppm, alternatively <NUM>-<NUM> ppm, further alternatively <NUM>-<NUM> ppm.

A critical aspect of the present invention is the molar ratio of monomer X to silver. Suitably the ratio of monomer X to silver is from <NUM>:<NUM> to <NUM>:<NUM>, alternatively from <NUM>:<NUM> to <NUM>:<NUM>, further alternatively from <NUM>:<NUM> to <NUM>:<NUM>, further alternatively from <NUM>:<NUM> to <NUM>:<NUM>, further alternatively from <NUM>:<NUM> to <NUM>:<NUM>, further alternatively <NUM>:<NUM> to <NUM>:<NUM>, further alternatively <NUM>:<NUM> to <NUM>:<NUM>, and further alternatively from <NUM>:<NUM> to <NUM>:<NUM>. When monomer X is present in multiple polymers, the total amount of monomer X from all sources is considered for the ratio calculation of monomer X to silver molar ratio.

This polymer complex is formulated by conventional means in the art and applied to a fiber or fabric to create a treated article. Suitable fabrics include cotton, polyester, and nylon, and alternatively polyester and nylon, and combinations thereof. Exhaustion and conventional padding processes are examples of suitable methods that may be used to apply the polymer complex to the fabric in the present invention. The preferred method of the present invention is padding. Following the application of polymer complex, the fabric may then be dried. Conventional drying methods may be used. The fabric is said to be "dry" when the weight of the fabric is equal to its initial weight before the drying treatment. In one embodiment of the present invention, the treated fabric is dry.

All fractions and percentages set forth below in the Examples are by weight unless otherwise specified.

A Lab scale padding machine from Werner Mathis AG (Model: CH-<NUM> VFM28888) was used to apply the antimicrobial compositions to fabric samples.

First, as standard in the field, fabric wet-pick up rate (WPUR) is determined to calculate the concentration of silver ion-polymer complex solution needed to achieve a target silver ion loading on the dried textile. The roller pressure is set to <NUM> barg initially. Then a <NUM> by <NUM> (<NUM>" by <NUM>") swatch of fabric is weighed out. Most fabric swatches will weigh between <NUM> to <NUM> grams. Polyester is typically <NUM> grams and heavy cotton is typically <NUM> grams. The swatch is soaked in a deionized water bath for <NUM> to <NUM> seconds until it has fully absorbed the water. Immediately after, the wet fabric is passed through the spinning rollers at the <NUM> barg pressure setting. The fabric is then reweighed to determine the weight increase due to water absorption. The WPUR is calculated by the difference in the weight of the wet fabric after going through the rollers and the dried fabric weight divided by the dried fabric weight. Polyester fabric used here typically weighed around <NUM> grams after and <NUM> grams before affording a wet pick-up rate of (<NUM>-<NUM>)/<NUM> or <NUM>%. Cotton typically weighs <NUM> grams dried and <NUM> grams after the roller for a calculated wet pick-up rate of (<NUM>-<NUM>)/<NUM> or -<NUM>%. Nylon typically weighed <NUM> grams dried and <NUM> grams after the roller for a calculated wet pick-up rate of (<NUM>-<NUM>)/<NUM> or -<NUM>%. If the wet pick-up rate does not match the desired value, the pressure of the padding rollers can be adjusted up or down to achieve the desired values. Fabric source and composition will directly impact the WPUR and should be determined in order to achieve the target silver ion fabric concentration.

Second, the application bath solutions are prepared to treat each textile swatch or fabric. The silver ion concentration in the bath is calculated based on the initial silver ion concentrate solution and the wet pick-up rate. The calculation of bath concentration of an antimicrobial formulation is calculated by dividing the target silver ion level by the active loading in the antimicrobial formulation and then dividing by the wet pick-up rate. For example, to target a theoretical <NUM> ppm of silver on polyester fabric with a <NUM>% wet pick-up rate using an antimicrobial formulation with <NUM> ppm of silver, one would divide <NUM> ppm Ag target/1000ppm Ag in formulation/(<NUM> WPUR*<NUM>), which is equivalent to <NUM> antimicrobial concentrate formulation in <NUM> of water. For the purposes of this invention, cotton and polyester treatments across all antimicrobial concentrate formulations (Table <NUM>, <NUM>-<NUM>) distinguished by varying VI:Ag+ molar ratios, were utilized similarly due to similar WPUR. The exception was for nylon fabric samples which achieved approximately <NUM>% wet pick-up rate, the calculation was <NUM> ppm Ag target/1000ppm Ag antimicrobial formulation/<NUM> WPUR*<NUM>, or <NUM> antimicrobial concentrate formulation in <NUM> of water.

The <NUM> ppm silver target fabric loading for cotton and polyester would be simply formulated by weighing out <NUM> grams of the antimicrobial concentrate formulation and mixing it into <NUM> grams of deionized water, and for nylon by weighing out <NUM> grams of antimicrobial concentrate formulation and mixing into <NUM> grams of deionized water. Due to silver ion-polymer complex stronger affinity to nylon versus cotton and polyester, baths were prepared at ~<NUM> ppm silver (or <NUM> grams of antimicrobial concentrate formulation) instead of <NUM> ppm to match desired fabric concentrations of approximately <NUM> ppm silver ion. For all fabrics used as controls (without antimicrobial treatment), fabrics were processed using water alone and are designated so in subsequent tables.

Lastly, the treatment of each fabric was carried out in the padding machine using the pressure settings determined above to achieve the desired wet pick-up rate for each fabric swatch. Each silver solution was poured into the trough on the padding machine prior to treatment. Then fabric samples were dipped into silver solutions for <NUM> to <NUM> seconds until soaked. Immediately, the wet fabric was then passed through the rollers to achieve the desired wet pick-up weights. Then fabrics were placed onto a device that stretches the fabric taught and dried in a convection oven at <NUM> for <NUM> minutes.

Antimicrobial concentrate formulations <NUM>-<NUM> supporting VI:Ag+ molar ratios from <NUM> to <NUM> are depicted in Table <NUM>. Each of the antimicrobial formulation examples contains approximately <NUM> ppm or approximately <NUM> ppm of silver ion which is added as a solution of <NUM>% silver nitrate in water. Each of the formulations were prepared by combining the water and polymer(s) together and mixing thoroughly first. Then adding the ammonia, which is a <NUM>% concentration of ammonia in water. Lastly, the silver nitrate solution is slowly mixed into the polymer solutions to achieve a clear single phase solution.

All fabrics were aged in a climate chamber (Model: KBWF <NUM> climate chamber, Binder Company) to accelerate color change. The <NUM> by <NUM> (<NUM>" by <NUM>") treated swatches of fabric were cut in half lengthwise to produce two strips of <NUM> by <NUM> (<NUM>" by <NUM>"). One strip was used in the climate chamber by first covering half of the sample, or about <NUM> by <NUM> (<NUM>" by <NUM>"), using a light-proof paper card on both sides and leaving the other have uncovered and exposed. Those strips were hung vertically inside the chamber. The chamber was then set to <NUM> and cycled humidity as follows: <NUM>% relative humidity for <NUM> hours, <NUM> hour transition from <NUM>% to <NUM>%, hold at <NUM>% for <NUM> hours, <NUM> hour transition from <NUM>% to <NUM>%, and repeated. This weathering cycle was repeated for <NUM> weeks. The light source was a LUMILUX Cool Daylight (OSRAM L36w/<NUM> lighting bulb) which was kept on during the weathering process.

The color of fabrics after weathering was measured using a Hunterlab Spectrophotometer (Model: Labscan XE) with illumination from a pulsed xenon arc source, a <NUM> degree illumination angle and a <NUM> degree viewer angle with a <NUM> (<NUM>") measuring area. Measurements were performed on <NUM> layers of the experimental fabrics using standard white tile as the backing. The untreated standard cotton, polyester, or nylon were used as control fabric to which all experimental fabric samples were compared to evaluate total color change (ΔE*ab) or by ISO Grey Scale interpretation. Larger ΔE*ab corresponds with greater fabric color change. For ISO analysis, the scale is <NUM>-<NUM>, with <NUM> representing minimal to no color change. ISO Grey Scale readings are an output of the spectrophotometer. The calculation of ΔE*ab is based on the measurements of L, a, and b which describe the coordinate space of light/dark, red/green, and blue/yellow. The ΔE*ab value is calculated as the square root of the sum of square differences between the measured sample values and the control sample.

Where the subscript <NUM> represents the control sample values and i represents the individual sample measurement. Each fabric swatch was measured at three locations and averages of L, a, and b values were used on the ΔE*ab calculations.

ΔE*ab below approximately <NUM> or ISO Grey Scale readings equal to or greater than <NUM> are preferred.

The fabrics were cut into <NUM> samples, and placed in sterile <NUM> conical tubes. The samples were inoculated with <NUM>µl Escherichia coli ATCC <NUM> inoculum. Samples were tested in triplicate, and one set of unpreserved samples was enumerated immediately after inoculation. The remainder of the bacterial samples were incubated at <NUM> and enumerated <NUM> hours post-inoculation. Bacteria were enumerated by adding <NUM> of Dey-Engley Neutralizing Broth to the samples and vortexing for <NUM> seconds. Aliquots of the cell suspensions were taken and enumerated using the Most Probable Number (MPN) method. (Modified ISO <NUM> Antimicrobial Efficacy Test).

Seven randomly selected panelists were given fabrics treated at various VI to Ag+ ratios using polymer and silver ion. Control fabrics were prepared using process water from tap without polymer or silver ion. Panelists were asked to compare hand feel changes relative to the process water treated polyester and nylon swatches or fabrics. The two categories of feedback were: <NUM>) harder hand/feel than reference, <NUM>) Same hand/feel as reference.

Claim 1:
A transition metal-polymer complex treated article comprising:
a) a monomer X selected from the group consisting of vinylimidazole, vinylimidazoline, vinylpyridine, vinylpyrrole, derivatives thereof and combinations thereof; and
b) a transition metal, wherein the transition metal is silver;
further wherein the molar ratio of monomer X to transition metal is from <NUM>:<NUM> to <NUM>:<NUM>.