Color-stable treated fabrics and methods of making the same

Abstract

The present invention relates to a color-stable treated fabric and a method for making the same.

Description

[0001] The present invention relates to a color-stable treated fabric and a method for making the same.

[0002] There are many biocides for incorporation into coating compositions, resin moldings, paper binders, and other polymeric materials to impart antimicrobial properties. The two main classes of active substances are organic (e.g., quaternary ammonium silanes) and inorganic (e.g., copper, silver, etc.). The most commonly used inorganic active substance is silver, or more precisely, silver ions. Typical carriers are silver nanoparticles, silver salts, ion exchange resins, and glass.

[0003] It is known that compositions containing inorganic antimicrobial agents (specifically silver ions) exhibit instability when exposed to heat, moisture and / or sunlight, resulting in discoloration. Discoloration has previously been discussed in US Pat. No. 7,993,415 B2 and US Pat. No. 7,754,625 B2. These inorganic biocides often produce color on light-colored or white fabrics, making them less than ideal. Therefore, the use of these compositions is effectively limited to systems that can tolerate such significant color changes.

[0004] Ohsumi et al. provide a method for inhibiting silver-related discoloration in US Pat. No. 5,698,229. Ohsumi et al. disclose a combination of an inorganic compound having silver ions supported thereon and benzotriazole.

[0005] Another approach for inhibiting discoloration is described by Ghosh et al. in U.S. Patent No. 7,390,774. Ghosh et al. disclose a copolymer comprised of heterocyclic monomers that are allegedly complexed with silver ions. The composition is light stable in a wet formulation. However, color stability performance on fabrics, particularly nylon and polyester fabrics, remains unresolved. Surprisingly, even at the upper limit of the molar ratio of VI monomer to silver ions disclosed in U.S. Patent No. 7,390,774, unacceptable color change was observed in the treated fabrics. Based on an upper limit weight ratio of VI to silver ions of 95:5, the disclosed upper limit molar ratio is 21.77:1.

[0006] However, there remains a need for new compositions that exhibit positive antimicrobial activity of metal ions, particularly on fabric compositions of cotton, polyester, nylon, and combinations thereof, without affecting the fabric's hand or color appearance, which may be caused by undesirable light stability issues due to the color of the metal (e.g., silver) and / or organic additives (e.g., polymers).

[0007] The present invention solves the problems in the art by providing a treated article comprising a fiber or fabric containing at least one silver ion-polymer complex; a monomer X selected from the group consisting of vinyl imidazole, vinyl imidazoline, vinyl pyridine, vinyl pyrrole, derivatives thereof, and combinations thereof; and a transition metal; wherein the molar ratio of monomer X to transition metal is from 24:1 to 117:1. The present invention also provides a method for making the treated article.

[0008] As used herein and in the appended claims, "fabric" means woven or nonwoven fabrics, such as cotton, polyester, nylon, lycra, polyolefins, and blends thereof.

[0009] As used herein and in the appended claims, "fiber" refers to a unit of matter that can be spun into yarn or made into fabric by bonding or interweaving in a variety of ways, including, for example, braiding, knitting, plaiting, felting, twisting, or weaving.

[0010] As used herein, the term "yarn" refers to strands of textile fibers in a form suitable for braiding, knitting, plaiting, felting, twisting, weaving, or otherwise making into fabrics.

[0011] As used herein and in the appended claims, the term "silver" refers to the silver metal incorporated into the antimicrobial composition of the present invention. Although it is not desired to specify the oxidation state (Ag) of the silver incorporated into the antimicrobial composition, 0 、Ag 1+ or Ag 2+ ) are constrained, but silver can be added to the antimicrobial composition by washing the polymer in a silver solution, such as silver nitrate in deionized water ("DI"). In addition to DI, other liquid media can also be used, such as water, aqueous buffer solutions, and aqueous organic solutions made with water-miscible organic substances (such as solvents, such as alcohols), surfactants, and softeners. Other silver sources 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 amount of silver to the antimicrobial composition to a saturated silver solution.

[0012] As used herein and in the appended claims, the term "(meth)" followed by another term such as acrylic acid, acrylate, acrylamide, etc., refers to, for example, acrylic acid and (meth)acrylic acid; acrylate and methacrylate; acrylamide and methacrylamide; etc. In addition, any acid described in a reference herein also includes the salt form, and vice versa.

[0013] All percentages expressed herein are wt % or ppm by weight. All range endpoints are inclusive and combinable.

[0014] According to the present invention, there is provided a textile comprising at least one transition metal polymer complex comprising at least one polymer and a transition metal.

[0015] The polymer of the present invention may suitably be a polymer comprising: a) 60 to 90 weight percent polymerized units of monomer X; and (b) 10 to 40 weight percent polymerized units of monomer Y, which monomer Y is an ethylenically unsaturated compound.

[0016] Monomer X of the present invention can be imidazole; thiophene; pyrrole; oxazole; thiazole and their respective isomers (e.g., thiazol-4-yl, thiazol-3-yl and thiazol-2-yl); tetrazole; pyridine; pyridazine; pyrimidine; pyrazine; oxazole; indazole; triazole and their respective isomers (e.g., 1,2,3-triazole and 1,2,4-triazole); and combinations thereof, such as imidazole 1,2,3-triazole-1,2,4-triazole; benzotriazole; methyl-benzotriazole; benzothiazole; methylbenzothiazole; benzimidazole and methylbenzimidazole. In one aspect of this embodiment, the antimicrobial composition of the present invention comprises a polymer having a heterocyclic group selected from imidazole, benzotriazole and benzimidazole. Preferably, monomer X is N-vinylimidazole.

[0017] In some embodiments of the present invention, monomer Y is selected from esters of carboxylic acids, organic sulfuric acids, sulfonic acids, phosphonic acids, and polymerized units of ethylene oxide, and combinations thereof. In some embodiments of the present invention, the ester comprising polymerized units of ethylene oxide comprises at least 2, or at least 3, or at least 4, or at least 5, or at least 6 units of ethylene oxide. The number of polymerized ethylene oxide units is calculated by the Mn of the polymerized ethylene oxide chain. In some embodiments of the present invention, the ester of polymerized units of ethylene oxide is a (meth)acryloyl ester. In some embodiments of the present invention, the polymerized units of ethylene oxide may be terminated at one end with a C1-C6 alkyl group. In some embodiments of the present invention, the polymerized units of ethylene oxide have an Mn from 100 to 3000. In some embodiments of the present invention, the polymerized units of ethylene oxide have an Mn from 200 to 1000, or from 250 to 600, or from 300 to 500.

[0018] In some embodiments of the present invention, monomer Y is selected from acrylic acid (AA), methacrylic acid (MAA), itaconic acid, maleic acid, fumaric acid, 2-acrylamido-2-methylpropanesulfonic acid and its sodium salt, and combinations thereof. In some aspects of these embodiments, the copolymer further comprises other ethylenically unsaturated monomers, such as (meth)acrylates, vinyl esters, (meth)acrylamides. A small amount of hydrophobic monomers, such as high-level alkyl (meth)acrylates (e.g., C-4 and higher) may be present without compromising water solubility. (Meth)acrylates may include mixed ethylene oxide / propylene oxide esters, provided that the ethylene oxide residues are at least 50% by weight (or at least 75%, or at least 90%) of the ethylene oxide / propylene oxide residues, or the esters of the mixed ethylene oxide / propylene oxide residues do not exceed 20% by weight of the copolymer, or do not exceed 15%, or do not exceed 10%. In some embodiments of the present invention, the mixed ethylene oxide / propylene oxide residues have an Mn of at least 150, or at least 300.

[0019] Alternatively, more than one polymer may be combined in the polymer complex of the present invention. Suitably, the second polymer may be a polymer comprising: (a) polymerized units of 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 95:5 to 5:95; or 80:20 to 20:80; or 60:40 to 40:60. Butyl acrylate is present in the copolymer in an amount of from 5% to 50%, or from 5% to 40%, and further or from 5% to 25%. Acrylic acid is present in the copolymer in an amount of from 5% to 30%, or from 5% to 20%, or from 5% to 10%.

[0020] According to the present invention, the first polymer and the second polymer may be present independently, together, and with or without additional polymers.

[0021] At least one transition metal is combined with at least one polymer to form a transition metal polymer complex. Suitable transition metals include, but are not limited to, copper, zinc, gold, silver, tin, and combinations thereof. Suitably, the transition metal is silver. When the transition metal in the transition metal polymer complex is silver, the silver may be present on the fiber or fabric at a silver concentration of 10-100 ppm, or 15-80 ppm, or further, 20-50 ppm.

[0022] A key aspect of the present invention is the molar ratio of monomer X to silver. Suitably, the ratio of monomer X to silver is from 22:1 to 117:1, or from 31:1 to 117:1, further or from 48:1 to 117:1, further or from 61:1 to 117:1, further or from 22:1 to 61:1, further or 24:1 to 61:1, further or 31:1 to 61:1, and further or from 48:1 to 61:1. When monomer X is present in multiple polymers, the total amount of monomer X from all sources is taken into account for the ratio calculation of the monomer X to silver molar ratio.

[0023] This polymer complex is formulated by conventional methods in the art and applied to fibers or fabrics to produce treated articles. Suitable fabrics include cotton, polyester and nylon, and or polyester and nylon, and combinations thereof. Exhaust dyeing methods and conventional padding methods are examples of suitable methods that can be used to apply the polymer complex to the fabrics of the present invention. The preferred method of the present invention is padding. After applying the polymer complex, the fabric can then be dried. Conventional drying methods can be used. When the weight of the fabric is equal to the initial weight before the drying treatment, the fabric is said to be "dry". In one embodiment of the present invention, the treated fabric is dry.

[0024] Some embodiments of the present invention will now be described in detail in the following examples.Unless otherwise indicated, all fractions and percentages listed below in the examples are by weight.

[0025] Examples

[0026] Materials and methods for making treated fabrics

[0027] Table 1: Chemicals used to produce antimicrobial concentrates

[0028]

[0029] Table 2: Textiles / Fabrics used for testing

[0030]

[0031] method:

[0032] Fabric treatment

[0033] The antimicrobial composition was applied to the fabric samples using a laboratory scale padder from Werner Mathis AG (Model: CH-8155 VFM28888).

[0034] First, as is standard in the art, the moisture absorption rate (WPUR) of the fabric is determined to calculate the concentration of the silver ion-polymer complex solution required to achieve the target silver ion loading on the dry textile. Initially, the roller pressure is set to 3 bar gauge. A 12" by 16" fabric sample is then weighed. Most fabric samples weigh between 10 and 15 grams. Polyester is typically 12 grams, and heavy cotton is typically 15 grams. The sample is soaked in a deionized water bath for 3 to 8 seconds until it has completely absorbed the water. Next, the wet fabric is passed through a spinning roller at a pressure setting of 3 bar gauge. The fabric is then reweighed to determine the weight gain due to water absorption. The WPUR is calculated by dividing the difference between the wet fabric weight after passing through the roller and the dry fabric weight by the dry fabric weight. The polyester fabric used here typically weighs approximately 24 grams after and 12 grams before, resulting in a moisture absorption rate of (24-12) / 12, or approximately 100%. Cotton typically weighs 15 grams dry and 30 grams after the roller, with a calculated moisture pickup of (30-15) / 15 or about 100%. Nylon typically weighs 12 grams dry and 27 grams after the roller, with a calculated moisture pickup of (27-12) / 12 or about 125%. If the moisture pickup does not match the desired value, the padding roller pressure can be adjusted up or down to achieve the desired value. The fabric source and composition will directly affect the WPUR and should be determined to achieve the target silver ion fabric concentration.

[0035] Secondly, a bath solution was prepared to treat each textile sample or fabric. The silver ion concentration in the bath was calculated based on the initial silver ion concentrated solution and the moisture absorption rate. The calculated bath concentration of the antimicrobial formulation was calculated by dividing the target silver ion level by the active substance loading in the antimicrobial formulation and then by the moisture absorption rate. For example, for an antimicrobial formulation with 1000 ppm silver, with a theoretical target of 30 ppm of silver on a polyester fabric with 100% moisture absorption, a target of 30 ppm of Ag would be used per 1000 ppm Ag in the formulation / (1.0 WPUR*100), which is equivalent to 3 g of antimicrobial concentrate formulation in 97 g of water. For the purposes of the present invention, due to similar WPURs, cotton and polyester treatments for all antimicrobial concentrate formulations (Tables 3, 1-13) were similarly used, differentiated by varying the VI:Ag+ molar ratio. The exceptions were the nylon fabric samples, which achieved approximately 125% moisture pickup, calculated as 30 ppm Ag target / 1000 ppm Ag antimicrobial formulation / 1.25 WPUR*100, or 2.4 g of antimicrobial concentrate formulation in 97.6 g of water.

[0036] The target fabric loading of 30 ppm silver for cotton and polyester will be simply prepared by weighing out 3 grams of the antimicrobial concentrate and mixing it into 97 grams of deionized water, and for nylon, by weighing out 2.4 grams of the antimicrobial concentrate and mixing it into 97.6 grams of deionized water. Because the silver ion-polymer complex has a stronger affinity for nylon than for cotton and polyester, a bath is prepared at approximately 15 ppm silver (or 1.5 grams of the antimicrobial concentrate) rather than 24 ppm to match the desired fabric concentration of approximately 30 ppm silver ions. For all fabrics used as controls (without antimicrobial treatment), the fabric was treated with water only and is designated as such in the subsequent tables.

[0037] Finally, each fabric was treated in a pad dyer using the pressure settings determined above to achieve the desired wet pickup for each fabric sample. Prior to treatment, each silver solution was poured into a tank on the pad dyer. The fabric sample was then immersed in the silver solution for 3 to 8 seconds until saturated. The wet fabric was then immediately passed through rollers to achieve the desired wet pickup weight. The fabric was then placed on a device that stretched the fabric taut and dried in a convection oven at 150°C for 2 minutes.

[0038] Antimicrobial concentrates:

[0039] Table 3 shows antimicrobial concentrate formulations 1-10 that support Vl:Ag+ molar ratios ranging from 4 to 117. Each example antimicrobial formulation contains approximately 1000 ppm or approximately 200 ppm of silver ions, added as a 50% aqueous silver nitrate solution. Each formulation is first prepared by combining water and one or more polymers and mixing thoroughly. Ammonia is then added as a 28% aqueous solution. Finally, the silver nitrate solution is slowly mixed into the polymer solution to obtain a clear, single-phase solution.

[0040] Table 3: 1000 pm Silver Ion Concentrated Antimicrobial Formulations 1-10

[0041]

[0042] Table 4: 200 pm Silver Ion Concentrated Antimicrobial Formulations 11-13

[0043]

[0044] Fabric weathering

[0045] All fabrics are aged in a climate chamber (model: KBWF 720 climate chamber, Binder Company) to accelerate color change. A 12 "by 16 " treated fabric sample is cut in half lengthwise to produce two 6 "by 16 " strips. In the climate chamber, one strip is used to cover half of the sample, or about 6 "by 8 ", using light-proof paper cards on both sides, and the other strip is uncovered and exposed. These strips are hung vertically in the climate chamber. The climate chamber is then set to 30 ℃ and the cycle humidity is as follows: 30% relative humidity for 4 hours, 2 hours from 30% transition to 90%, keep 90% for 4 hours, 2 hours from 90% transition to 30%, and repeat. This weathering cycle is repeated for 3 weeks. The light source is a LUMILUX cold light fluorescent lamp (OSRAML36w / 865 lighting bulb), which remains turned on during the weathering process.

[0046] Color Measurement

[0047] The color of the fabric after weathering was measured using a Hunterlab spectrophotometer (model: Labscan XE) with illumination from a pulsed xenon arc light source, an illumination angle of 0 degrees and an observation angle of 45 degrees, and a measurement area of ​​13 mm (0.5"). Two layers of experimental fabric were measured using a standard white tile as a backing. Untreated standard cotton, polyester, or nylon was used as a control fabric, and all experimental fabric samples were compared to the control fabric or interpreted by the ISO gray scale to evaluate the total color change (ΔE * ab). Larger ΔE * ab corresponds to a greater change in fabric color. For ISO analysis, the scale is 1-5, with 5 indicating minimal or no change in color. The ISO grayscale reading is the output of the spectrophotometer. ΔE * The calculation of 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 ab value was calculated as the square root of the sum of the squared differences between the measured sample values ​​and the control samples.

[0048] Where subscript 0 represents the control sample value and i represents the individual sample measurement value. Each fabric sample was measured at three locations and the average of the L, a, and b values ​​was used for ΔE * ab calculation.

[0049]

[0050] Less than ΔE of approximately 1.3 * An ab or ISO grayscale reading of 4.5 or greater is preferred.

[0051] Antimicrobial performance testing

[0052] The fabric was cut into 0.4 g samples and placed in a sterile 50 mL conical tube. The samples were inoculated with 200 μl of Escherichia coli ATCC 8739 inoculum. The samples were tested in triplicate and a set of unpreserved samples were counted immediately after inoculation. The remaining bacterial samples were incubated at 37 ° C and counted 24 hours after inoculation. The bacteria were counted by adding 20 mL of Dey-Engley neutralizing broth to the sample and vortexing for 25 seconds. An aliquot of the cell suspension was taken and counted using the most probable number (MPN) method. (Modified ISO 20743 antimicrobial efficacy test).

[0053] Qualitative feel test

[0054] Fabrics treated with polymer and silver ions at varying V1 to Ag+ ratios were given to seven randomly selected panelists. A control fabric was prepared using industrial water from tap water without polymer or silver ions. Panelists were asked to compare the change in hand relative to polyester and nylon samples or fabrics treated with industrial water. Two types of feedback were provided: 1) a harder hand than the reference, and 2) the same hand as the reference.

[0055] Experiments and results

[0056] Table 5: Comparative Example 1, Cotton, Nylon, and Polyester Fabric Discoloration with a Molar Ratio Less Than 22 Moles of VI / Mole of Silver Ion

[0057]

[0058] Note: ΔE * ab (aged relative to untreated) is a measure of color stability by comparing the color difference of treated fabric to untreated fabric over time.Comparative Example 1 demonstrates the yellowing (discoloration) associated with compositionally defined treatments of polyester, nylon, and cotton.

[0059] Table 6: Inventive Example 2 showing the color change performance of cotton with a VI:Ag+ molar ratio greater than 4:1.

[0060]

[0061] Table 7: Inventive Example 3 showing the color change properties of polyesters with molar ratios greater than 4:1.

[0062]

[0063] Table 8: Inventive Example 3 showing the color change properties of nylon with a molar ratio greater than 4:1.

[0064]

[0065] Table 9: Inventive Examples showing initial visible fabric color and hand for VI / Ag+ molar ratios up to 1000:1.

[0066]

Claims

1. An article treated with a transition metal-polymer complex, the article comprising: a) a monomer X selected from the group consisting of: Vinylimidazole, vinylimidazoline, vinylpyridine, vinylpyrrole, derivatives thereof, and combinations thereof; as well as b) a transition metal, wherein the transition metal is a silver ion; Furthermore, the molar ratio of monomer X to transition metal is from 24:1 to 117:

1.

2. The treated article of claim 1, wherein The treated article is a fiber or a fabric.

3. The treated article of claim 1, wherein The molar ratio of monomer X to transition metal is from 31:1 to 117:

1.

4. The treated article of claim 1, wherein The monomer X is vinyl imidazole.

5. The treated article of claim 1, wherein The treated article is a fiber selected from the group consisting of cotton, nylon, polyester, and combinations thereof.

6. A method for treating fibers or fabrics, the method comprising: a) Provide fiber or fabric b) providing at least one transition metal polymer complex, said complex comprising: i) a monomer X selected from the group consisting of vinyl imidazole, vinyl imidazoline, vinyl pyridine, vinyl pyrrole, derivatives thereof, and combinations thereof; and ii) a transition metal, wherein the transition metal is a silver ion; wherein the molar ratio of monomer X to transition metal is from 24:1 to 117:1, and c) contacting the fibers or fabric with the at least one polymer complex.

7. The method according to claim 6, wherein: The molar ratio of monomer X to silver ions is from 31:1 to 117:

1.

8. The method of claim 6, wherein: The monomer X is vinyl imidazole.

9. The method of claim 6, wherein: The method comprises contacting a fiber selected from the group consisting of cotton, nylon, polyester, and combinations thereof with at least one polymer complex.

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