PLANT BASED ANTI-MICROBIAL FABRIC TREATMENT, TREATED FABRICS, AND ASSOCIATED METHODS

Abstract

A process for effectively binding plant-based antimicrobials to various fabrics which provides for long term antimicrobial effect of the fabric and the resultant fabric.

Claims

1. A method of forming an antimicrobial fabric, the method comprising: providing an aqueous solution comprising from 1% to 20% tea tree oil, from 1% to 20% citric acid, from 1% to 20% of a binder, and from 0.5% to 5% of an emulsifier; 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 aqueous solution further comprises 0% to 5% of a defoamer.

3. The method of claim 2 wherein said defoamer comprises a nonionic non-silicone defoamer

4. The method of claim 3 wherein said defoamer comprises an oil-based defoamer.

5. The method of claim 4 wherein said defoamer is made up mostly of petroleum products,

6. 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.

7. The method of claim 6 wherein said binder comprises a polar aprotic solvent.

8. The method of claim 7 wherein said binder comprises N-methyl-2-pyrrolidone (e.g. NMP), dimethylformamide, dimethylsulfoxide, dimethylacetamide, or Hexamethylphosphoramide (HMPA).

9. The method of claim 1 wherein said emulsifier comprises a non-ionic surfactant.

10. The method of claim 9 wherein said emulsifier comprises polyoxyethylene castor oil, ethoxylated castor oil, or polyoxl n castor oil (n=40-60).

11. 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%.

12. The method of claim 11 wherein said application load level is between 5% and 15%.

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

14. The method of claim 11 wherein said wet process comprises an “exhaust” process.

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

16. An antimicrobial fabric comprising: interconnected synthetic fibers; said interconnected synthetic fibers having been exposed to an aqueous solution comprising from 1% to 20% tea tree oil, from 1% to 20% citric acid, from 1% to 20% of a binder, from 0.5% to 5% of an emulsifier, and from 0% to 5% of a defoamer for a period of time and then dried.

17. The fabric of claim 16 wherein said defoamer comprises an oil-based defoamer made up mostly of petroleum products,

18. The fabric of claim 16 wherein said binder comprises N-methyl-2-pyrrolidone (e.g. NMP), dimethylformamide, dimethylsulfoxide, dimethylacetamide, or Hexamethylphosphoramide (HMPA).

19. The fabric of claim 16 wherein said emulsifier comprises polyoxyethylene castor oil, ethoxylated castor oil, or polyoxl n castor oil (n=40-60).

20. The fabric of claim 16 wherein said exposing includes a wet process with said aqueous solution being applied to said fabric with an application load level of between 1% and 20%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG. 1 shows a comparison of the antimicrobial properties of fabrics treated with tea tree oil alone, citric acid alone, 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)

[0045] 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. 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. 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, or 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 of these is that many of them are relatively strong antimicrobials. One of the most effective plant-based antimicrobial compounds 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 is known to have, at least, strong antibacterial and antifungal properties and 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 is known to destroy well over 99.9% of bacteria and can do so when impregnated into fabric. However, after just 25 washings, the 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 antiviral 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 subject to 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] As indicated above, the present invention comprises a mixture of tea tree oil and citric acid along with a binder being used as a treatment for fabrics. 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, from 0%-5% defoamer, and with the remainder of the solution comprising water.

[0053] The treatment 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).

[0054] 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.

[0055] 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%.

[0056] The binder present in the solution can comprise a variety of binders 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 many cases the binder will comprise a polar aprotic solvent such as, but not limited to, N-methyl-2-pyrrolidone (e.g. NMP), dimethylformamide, dimethylsulfoxide, dimethylacetamide, or Hexamethylphosphoramide (HMPA). The binder may be activated by heat in the drying process or via another mechanism.

[0057] The emulsifier present in the solution can comprise a variety of emulsifiers 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. A the same time, as shown in FIG. 1, inclusion of a emulsifier of certain types can 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.

[0058] The defoamer present in the solution 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

[0059] As can be seen in FIG. 1, fabrics treated with just tea tree oil 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.

[0060] 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 is clear 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.

[0061] 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.

[0062] 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. Modifications and variations of the described embodiments may be made without departing from the spirit and scope of the invention.

[0063] 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.