Plant Based Anti-Microbial Fabric Treatment, Treated Fabrics, and Associated Methods

Abstract

A process, and the resultant product. for effectively binding plant-based materials to various fabrics to provide for antimicrobial effect of the fabric. The fabrics and methods will typically maintain microbial reduction characteristics even after repeated laundering.

Claims

1. A method of forming an antimicrobial fabric, the method comprising: providing an aqueous solution comprising from 0.01% to 1% tea tree oil, from 0.1% to 5% citric acid, from 0.5% to 15% of a binder, and at least 75% water, by weight; exposing a fabric to said aqueous solution for a period of time; and drying said fabric after said exposing.

2. The method of claim 1 wherein said binder comprises a polymer that serves to crosslink reactive end groups of the solution to the fabric surface.

3. The method of claim 1 wherein said binder is plant-based.

4. The method of claim 1 wherein said exposing includes a wet process with said aqueous solution being applied to the fabric with an application load level of between 1% and 20%.

5. The method of claim 4 wherein said application load level is between 5% and 15%.

6. The method of claim 11 wherein said wet process comprises a continuous Pad-Dry process.

7. The method of claim 4 wherein said wet process comprises an exhaust process.

8. The method of claim 1 wherein said drying comprises: placing said fabric on a tenter frame containing heating zones which activate the binder.

9. An antimicrobial fabric comprising: interconnected synthetic fibers; said interconnected synthetic fibers having been exposed to an aqueous solution comprising an aqueous solution comprising from 0.02% to 1% tea tree oil, from 0.1% to 5% citric acid, from 0.5% to 15% of a binder, and at least 75% water, by weight for a period of time and then dried.

10. The fabric of claim 9 wherein said binder comprises a polymer that serves to crosslink reactive end groups of the solution to the fabric surface.

11. The fabric of claim 9 wherein said binder is plant-based.

12. The fabric of claim 9 wherein said exposing includes a wet process with said aqueous solution being applied to the fabric with an application load level of between 1% and 20%.

13. The fabric of claim 12 wherein said application load level is between 5% and 15%.

14. The fabric of claim 12 wherein said wet process comprises a continuous Pad-Dry process.

15. The fabric of claim 12 wherein said wet process comprises an exhaust process.

16. The fabric of claim 9 wherein said drying comprises: placing said fabric on a tenter frame containing heating zones which activate the binder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIGS. 1 shows a comparison of the antimicrobial properties of fabrics treated with tea tree oil, citric acid, a combination of tea tree oil and citric acid, and the combination of tea tree oil and citric acid, and the combination of tea tree oil, citric acid, and an emulsifier. All the efficacies are shown after 50 washings and two different times of exposure.

DESCRIPTION OF PREFERRED EMBODIMENT(S)

[0042] As discussed herein, the terms thread, yarn, and fiber are often used interchangeably although those terms are often provided with specific meaning in the art. However, they are all, in some respects, the act of interconnecting filaments to form suitable materials for fabric construction.

[0043] Fibers and textiles of fiber includes natural and synthetic fibers and specifically includes, but is not limited to: abaca, acetate, acrylic, alfa, alginate, alpaca, angora, anidex, aramid, azlon, bamboo, beaver hair, broom, camel hair, cashgora, cashmere, chitin, chiengora, chlorofibre, coir, cotton, cupro, elastane, elasterell-p, elastodiene, elastoester, elastolefin, elastomultiester, flax, fluorofibre, glass, guanaco, hemp, henequen, jute, kapok, kenaf, lambswool, lastol, lastrile, llama, lycra, lyocell, maguey, melamine, metallic, modacrylic, modal, mohair, novoloid, nylon, nytril, olefin, other animal hairs, papyrus, pina, polyamide, polybenzimidazole (PBI), polylactic acid (PLA), polycarbamide, polyester, polyethylene, polyethylene, terephthalate, polyimide, polylactide, polyphenylene sulphide, polypropylene, polyurethane, polyvinyl chloride, protein, qiviut, rabbit, raffia, rayon, ramie, rubber, saran, silk, sisal, soy silk, spandex, sulfar, sunn, tencel, triacetate, triexta, trivinyl, vicuna. vinal, vinyla, vinyon, viscose, wool, and yak fibers and/or hairs.

[0044] Further fabric as used herein will generally comprise any form of material made through the interconnection of any combination of filaments, threads, yarns, or fibers. Although the fabrics may be described as a woven material, this description is not intended to be limited only to weaves and woven material, those are simply a common and well understood example. Materials and fabrics within the scope of this disclosure include without limitation any materials woven, knitted, bound, bonded, crocheted, knotted, tatted, felted, braided, or otherwise formed.

[0045] Such materials include fabrics or other materials formed by application of heat and/or pressure to filaments or other materials. For example, and without limitation, this application includes within its scope non-woven materials made to form fabrics that are not woven or knitted, such as felts. Accordingly, as would be appreciated by a person of ordinary skill in the art, the teachings herein are applicable to fabrics made by any method known to persons of ordinary skill in the art. Further, the use of the term garment as used herein is primarily to indicate any article of clothing and particularly those constructed from a fabric. However, it should be recognized that the systems and methods discussed herein can be used on other fabric objects which may not be garments such as, but not limited to, industrial fabrics, outdoor textiles, or architectural fabrics, or may be used on fabric objects which may occasionally be used as garments even if it is not their primary purpose.

[0046] Essential oils of various plants are used in a large number of human applications. They are commonly used for flavoring in cooking as well as in various skin creams, balms, and salves. In many respects, essential oils can be considered a distillation of the chemical composition of a plant into a particularly concentrated form. Most have a strong scent or taste which is often what they are valued for (for example, vanilla or orange oil), however, it has recently been discovered that many plant oils may have other properties. One interesting plant-based antimicrobial compound is Terpinen-4-ol. It is an isomer of terpinol and a monoterpene and is found in a number of plants including in oranges, mandarins, oregano, New Zealand lemonwood tree, Japanese cedar and black pepper. However, it is most known as being a primary component of tea tree (Maelaleuca alternifolia) oil. Terpinen-4-ol has been placed into a variety of human uses in body products.

[0047] While tea tree oil is an effective antimicrobial, its traditional uses are on the skin where it is either absorbed to assist the skin's own auto-defense functions, or is placed into direct contact with microbes whose elimination is desired (such as in the treatment of wounds). In fabric, tea tree oil is generally an ineffective antimicrobial as it is readily removed by laundering and therefore lacks the ability to function over a time of extended use. After as few as ten washings, the effectiveness of tea tree oil treated fabric has typically fallen well below the level as to be effective.

[0048] Effectiveness of an antimicrobial is typically measured by its elimination capability. No antimicrobial will completely kill all microbes which it ends up in proximity to, however, a significant reduction in concentration is effectively complete removal as the small amount remaining are typically unable to reproduce fast enough to avoid destruction from a human immune system, or to simply not be noticed (e.g. in the case of odor causing bacteria). Elimination of greater than 99% of a particular form of microbe is typically required for a product to be considered antimicrobial and most actually destroy around 99.9% to 99.99% of such microbes. Tea tree oil can destroy well over 99.9% of bacteria in certain forms and applications. However, after just 25 washings after being placed in or on fabric, its effectiveness can have fallen to as low as 65% which is, most all intents and purposes, sufficiently low as to have no noticeable antimicrobial effect.

[0049] Citric Acid is also known to be an antimicrobial although it is more commonly used as a pH adjuster, chelating agent, or preservative in various cleaners. Citric Acid is primary encountered naturally in citrus fruits (such as lemons, limes and oranges) and it is what gives them their tart sour flavor. However, it may be produced at large scale via molds or through certain synthesis reactions. Citric acid is naturally produced in a large number of plants as citrate, which is a primary part of the TCA cycle present in the central metabolic pathway.

[0050] In order to provide for an effective antimicrobial fabric which obtains its antimicrobial properties from plant-based materials, it is desirable to provide a blend of citric acid and tea tree oil. The blend will typically be provided to the fabric or to the underlying yarns as a topical treatment where it can be bound to the fabric or yarn via a binding agent. This will typically occur once the fabric has been constructed into a garment but may occur at the fabric or thread stage. The fabric to which it is applied may be natural (e.g. wool or cotton) or may be from synthetic fibers (such as polyester or spandex). The synthetic fibers may be virgin fibers or may be recycled from other materials. In an alternative embodiment, if the fabric is intended to have antimicrobial properties when manufactured, the binding agent may be included as part of such synthetic fibers during manufacturing to prepare the yarn or fabric for exposure to the tea tree oil and citric acid blend. This is, however, generally not preferred.

[0051] Synthetic fibers are particularly common in exercise clothing due to their light weight, quick dry, stretchability, and skin hugging capability. As this type of clothing is also one which is commonly exposed to large amounts of sweat, it can also be associated with substantial odor between launderings. Further, injuries during exercise and sports can also regularly occur which can make microbial colonies in exercise clothing particularly dangerous. For at least these reasons, providing antimicrobial capability to fabric including synthetic fibers (either alone or in combination with natural fibers) can be particularly valuable. However, synthetic fiber-based fabrics can also be more difficult to effectively impregnate with other materials due to the structure of synthetic fibers when compared to more naturally occurring fibers.

[0052] U.S. patent application Ser. No. 17/734,784, the entire disclosure of which is herein incorporated by reference, provides for systems and methods of producing an antimicrobial fabric, along with the resultant fabric, that utilizes a combination of citric acid and tea tree oil to provide antimicrobial efficacy which is resistant to removal in washing. The mixture will typically be applied in an aqueous solution in the same manner as a fabric dye or treatment with the solution acting as the liquor bath in the treatment process. The solution may comprise, in an embodiment, from 1-20% tea tree oil, from 1-20% citric acid, from 1-20% binder, from 0.5%-5% emulsifier, and from 0%-5% defoamer, by weight with the remainder of the solution comprising water.

[0053] It has further been determined that substantially smaller amounts of both the tea tree oil and the citric acid may be used and still produce an effective antimicrobial fabric. Specifically, the antimicrobial effect can be obtained with greater reliance on the inclusion of citric acid as the primary antimicrobial agent with a tea tree oil compound acting as more of an excipient in the resultant coating making the antimicrobial effect of the citric acid more pronounced. Alternatively the tea tree oil may act as a binder in the binding of the citric acid to the fabric or may fulfill both the role of excipient and binder to a greater or lesser degree. In embodiments of such an alternative formulation, the antimicrobial bath is comprised of an aqueous solution comprising from about 0.01% to 1% tea tree oil which will often be in the form of a tea tree oil compound which may be from about 1% to about 5% of the resulting bath. In an embodiment, the tea tree oil compound may be a micro-encapsulated form of tea tree oil. The bath will typically comprise from 0.1% to 5% citric acid which may also be provided in the form of a compound, from 0.5% to 15% of a binder, and at least 75% water. Typically, the remaining ingredients may be standard additions for chemical materials such as stabilizing materials, preservatives, and materials to alter the chemical handling of the antimicrobial formulation. In an embodiment, the tea tree oil may be provided in the form of a micro encapsulation.

[0054] The treatment solution will be applied to the fabric via any form of fabric wet process methodology. Typically, the solution will be applied to the fabric with the specific application load level of the solution being around 1-20% with 5-15% typically being more preferred. However, the specific amount of solution used for a fabric may depend on the particular type of fabric, and the specific fiber content of the fabric to which the solution is being applied, as well as the treatment methodology used. In many cases, the fabric will comprise a fabric including both synthetic and natural fibers in combination. However, such solutions may also be used on fabrics formed of purely synthetic fabrics (either of uniform fiber type or with combinations of fibers of different types) or on fabrics including only natural fibers (again including those of uniform fiber type or with combinations of fibers of different types).

[0055] In an embodiment, the fabric would be treated using a continuous Pad-Dry method for fabric finishing as that term is commonly understood by one of ordinary skill in the art. In such a method, a continuous roll of fabric would typically be immersed in a trough containing a particular strength of the antimicrobial solution and then padded through rubber squeeze rollers (also called a mangle or wringer) to impart a consistent wet pick up level. The pad operation is normally on the entry end of a tenter frame which contains heating zones used to dry the fabric and impart durability from activating the binder.

[0056] Alternatively, the fabric may be treated using the exhaust method of wet processing where a certain weight or length of fabric (a batch) will typically be placed within a bath of the solution (liquor) and exhausted on to the fabric at elevated temperatures for a specified period of time before it is removed. The fabric is then run down the tenter frame as previously mentioned to dry the fabric and impart durability. Exhaust methods typically utilize a jet machine but can be accomplished by other machines such as a jigger, winch, beam, or garment machine. As previously mentioned above, the specific application load level of the solution in any of the above methodologies will typically be within the same 1-20% and often within 5%-15%.

[0057] The binder present in the solution can comprise a variety of binders and/or binder packages (including, for example, a bunder and cross-linking agent in combination) and essentially serves to provide chemical attachment to the surface of the fabric to impart further durability for maintaining the citric acid and/or tea tree oil to the fabric through extended laundering cycles. The binder, in an embodiment, will be a polymer that serves to crosslink reactive end groups of the solution to the fabric surface. While a variety of binders can be used and may be altered depending on the composition of the substrate fabric, in order to provide a more biological-based bath, the binder may comprise a biological-based, plant-based, and/or plant-derived binder or binder blend. In an embodiment, the binder may be a polysaccharide-based binder. The binder may be activated by heat in the drying process or via another mechanism.

[0058] The emulsifier or stabilizer present in the solution will often act as a rheology modifier and can comprise a variety of emulsifiers and/or stabilizers and is primarily included to provide viscosity and stability to the solution as would be understood by a person of ordinary skill in the art. At the same time, inclusion of a emulsifier of certain types could improve retention of the tea tree oil and citric acid combination in the fabric. The emulsifier, in an embodiment, will be a non-ionic surfactant such as those typically used in dyeing or other aspects of the manufacture of fabric and may have a pH of about 5.5 to about 8.0 (in 5% solution). In an embodiment, the emulsifier comprises polyoxyethylene castor oil, ethoxylated castor oil, polyoxl n castor oil (n=40-60), or any similar compound or combination of compounds. In an alternative embodiment, such compounds could be included for alternative effect including to directly provide for additional anti-microbial capability.

[0059] The defoamer, if present in the solution as it is optional, can comprise a variety of defoamers and/or antifoamers and is primarily included to provide for foam control during processing as would be understood by a person of ordinary skill in the art. In an embodiment, the defoamer will comprise a nonionic non-silicone defoamer for aqueous solutions. This will often comprise an oil-based defoamer made up mostly of petroleum products, but oil-based materials may also be based on synthetic oils, vegetable oils, or other oils. The defoamer will typically have a pH of about 6.0 to about 7.0 in 2% solution

[0060] As can be seen in FIG. 1, fabrics treated with just a tea tree oil compound and binder (101), after 50 washings, have essentially lost all effective antimicrobial capability (with elimination at best below 80% even after 24 hours of exposure) and also show wide variability in antimicrobial capability with one sample retaining essentially no capability at all. Fabrics treated with just citric acid and binder (103) show improved performance with elimination in the 80% or higher range, but the fabrics still have wide variability and lack consistent elimination in the 90%, 95%, 99%, 99,9%, or 99.99% range which are often required to be effective antimicrobial materials.

[0061] However, as can be seen toward the right of FIG. 1, fabrics treated with a combination of tea tree oil, citric acid, and binder (105) in the manner discussed above are still strongly antimicrobial and are clearly more consistently antimicrobial than one treated with just one of the constituents. With the combination, elimination in the upper 90% range is obtained even after the shorter window of exposure while near 100% elimination is obtained in the longer exposure window. Still further, a combination of tea tree oil, citric acid, binder, and polyoxyethylene castor oil (107) shows strong maintenance of antimicrobial capability of essentially 100% even after 50 washings. From this figure, it appears that the combination of materials as contemplated above unexpectedly outperforms either material alone and what would be expected from the combination based on the individual performance of the constituents.

[0062] The qualifier generally, and similar qualifiers as used in the present case, would be understood by one of ordinary skill in the art to accommodate recognizable attempts to conform a device to the qualified term, which may nevertheless fall short of doing so. This is because terms such as circular are purely geometric constructs and no real-world component or relationship is truly circular in the geometric sense. Variations from geometric and mathematical descriptions are unavoidable due to, among other things, manufacturing tolerances resulting in shape variations, defects and imperfections, non-uniform thermal expansion, and natural wear. Moreover, there exists for every object a level of magnification at which geometric and mathematical descriptors fail due to the nature of matter. One of ordinary skill would thus understand the term generally and relationships contemplated herein regardless of the inclusion of such qualifiers to include a range of variations from the literal geometric meaning of the term in view of these and other considerations.

[0063] While the invention has been disclosed in conjunction with a description of certain embodiments, including those that are currently believed to be useful embodiments, the detailed description is intended to be illustrative and should not be understood to limit the scope of the present disclosure. As would be understood by one of ordinary skill in the art, embodiments other than those described in detail herein are encompassed by the present invention.

[0064] Modifications and variations of the described embodiments may be made without departing from the spirit and scope of the invention.

[0065] It will further be understood that any of the ranges, values, properties, or characteristics given for any single component of the present disclosure can be used interchangeably with any ranges, values, properties, or characteristics given for any of the other components of the disclosure, where compatible, to form an embodiment having defined values for each of the components, as given herein throughout. Further, ranges provided for a genus or a category can also be applied to species within the genus or members of the category unless otherwise noted.