Abstract:
Disclosed is a method for preparing a multifunctional technical textile that exhibits multiple functional properties comprising flame or fire-retardancy, EMI shielding, anti-odorous property, UV protection, oil-repellency, anti-soiling property, antimicrobial property, anti-creasing property, water-proof, and antistatic property. The method comprises washing a textile product in a water solution comprising water mixed with a predetermined quantity of non-ionic detergent, storing the textile product at a predetermined temperature and a predetermined relative humidity, and subjecting the textile product to plasma treatment by placing the same in a plasma stream within a reaction chamber.

Description:
FIELD OF THE INVENTION 
     The present invention relates to various treatments of textiles, more particularly to plasma-treatments of textiles, and even more particularly to a plasma-treatment method for obtaining multifunctional technical textiles. 
     BACKGROUND OF THE INVENTION 
     Technical textiles are a specialized textile product used primarily for their function rather than for their aesthetic purposes. Some of the functions of the technical textiles are EMI shielding, water-proofing, fire and flame resistance, antistatic function, antimicrobial function, fire-resistance, and anti-odor function. The clothing made from the technical textiles is commonly referred to as protective clothing, which is used for various applications. For example, the protective clothing with an antistatic property or characteristic is used by the operators of a gas station, firefighters, and the like, as such clothing prevents the accumulation of electric charges on the surface thereof. Protective clothing with antimicrobial function is another product of technical textiles which helps in preventing the cross-transmission of infectious diseases, and is therefore used in hospitals, medical laboratories, and so on. Yet another example would be fire-resistant clothing typically worn by firefighters while performing firefighting operations. 
     In spite of various types of protective clothing known in the prior art, there&#39;s still a need for technical textiles that exhibit more than one function. For example, a protective clothing used in medical facilities might need to be water-proof while being anti-microbial. Similarly, another example would be a sportswear which needs to have an anti-odor function while exhibiting an anti-UV property. Several attempts have been made in the art to address the need for multifunctional technical textiles, however, the multifunctional textiles made out of these attempts comprises more than one layer of cloth and is therefore bulky and heavy causing inconvenience to the wearer. Therefore, there exists a need for a multifunctional technical textile which is light and single or uni-layered. 
     Further, the technical textiles are typically manufactured by a multi-stage wet process which consumes a lot of time. And on top of that, these wet processes are not eco-friendly as they produce a lot of wastewater which is hazardous to the environment. Hence, it is desirable to manufacture light, single-layered, multifunctional technical textiles from a dry, quick, eco-friendly method. 
     SUMMARY OF THE INVENTION 
     It is a primary object of the present invention to provide a method of treatment of textiles in order to obtain light, single-layered multifunctional technical textiles. 
     It is another object of the present invention to provide such a method of treatment which is dry and eco-friendly. 
     It is yet another object of the present invention to provide such a method of treatment which is a single-stage process. 
     It is still yet another objective of the present invention to provide such a method of treatment which is less time-consuming compared to conventional methods that are employed for obtaining technical textiles. 
     It should also be understood that many other advantages and alternatives for practicing the invention will become apparent from the following detailed description of the preferred embodiments and the appended drawings. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         FIG. 1  is an illustration of the reaction chamber employed for low-pressure plasma treatment of the textile product in accordance with the present invention. 
         FIG. 2  is an illustration of the reaction chamber employed for atmospheric-pressure plasma treatment of the textile product in accordance with the present invention. 
     
    
    
     FIGURES—REFERENCE NUMERALS 
     
         
           10  . . . Reaction Chamber for Low-Pressure Plasma Treatment 
           12  . . . Anode 
           14  . . . Cathode 
           16  . . . Guide Roll 
           18  . . . Reaction Chamber for Atmospheric-Pressure Plasma Treatment 
           20  . . . Electrode 
           22  . . . Trolley 
           24  . . . Textile Product 
           26  . . . Precursor Material 
       
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is a method of treatment of textiles with plasma for obtaining multifunctional technical textiles. The method of plasma-treatment of the present invention is clean, dry and eco-friendly as it doesn&#39;t involve treatment with chemicals, liquids including water. Also, the plasma-treatment method is a single-stage method and is therefore less time-consuming compared to the treatments directed to the same end as the plasma-treatment method of the present invention. In fact, the time required for the completion of the method of plasma-treatment of the present invention does not exceed five minutes. The final product of the plasma-treatment method is a multifunctional textile is a technical textile that is single-layered and exhibits more than one property or characteristic. Multifunctional textile so obtained, similar to a conventional technical textile, is used in various fields of application. For example, the multifunctional textile can be used as a medical textile as the multifunctional textile is both water-proof and antimicrobial. Similarly, the multifunctional textile can be used as a sportswear as exhibits both odor-free and anti-UV characteristics. 
     Prior to the initiation of the plasma-treatment method of the present invention, a textile product is washed in a solution comprising water mixed with non-ionic detergent water following the ratio of 1 gram per liter of water. More particularly, the textile product is washed at 40° C. for 10 minutes. Once washed, the textile product is stored at 20° C. and at 65% relative humidity. The textile product, such as a cloth, may be woven, knitted, non-woven, and so on. 
     The plasma used for the present invention can pertain to inert gases, particularly argon, or to reactive gases such as oxygen, nitrogen or nitrogen containing polymeric gases, and so on, with nitrogen plasma being preferable. Both low-pressure and atmospheric pressure plasma discharges can be used for the plasma-treatment. It is to be noted that the gases used for the plasma-treatment are pure grade. 
     Referring to  FIG. 1 , for the low-pressure plasma treatment, a cylindrical reaction chamber  10  made of glass is employed for generating the low-pressure plasma from a gas. A rotary pump is employed for evacuating the reaction chamber  10  before filling up the same with a gas from which plasma is generated. The gas within the reaction chamber  10 , which is preferably nitrogen, is maintained at a pressure of 10 −2  Torr. The reaction chamber  10  further comprises a pair of electrodes, viz., an anode  12  and a cathode  14  wherein, when the electrodes are powered, a glow discharge is radially produced between the same. The gas between the electrodes is subjected to electromagnetic force resulting in the generation of plasma. An axial magnetic field formed within the reaction chamber  10  ensures uniform distribution of the plasma medium. The textile product  24  is placed on the anode  12  so as to be exposed to the plasma. In one embodiment, the reaction chamber  10  comprises a plurality of guide rolls  16  whereon the textile product  24  is transported in and out of the reaction chamber  10 . The surface of the textile product  24  reacts with the plasma so as become a multifunctional textile. 
     In one embodiment, argon plasma is used in the reaction chamber instead of nitrogen plasma. In this case, metallic particles are attached to the surface electrodes, whereby, upon the initiation of the plasma-treatment, the metallic particles are sputtered over the surface of the textile product forming a nano-layer of the metallic particles thereon. The antimicrobial property of the multifunctional textile is substantially increased with the deposition of metallic particles. The thickness of the nano-layer of the metallic nanoparticles depends on the electrodes, their shape and size, voltage supplied to the electrodes, and so on. In another embodiment, copper, silver, gold, and titanium are used as electrodes, which also enhance the antimicrobial properties of the multifunctional textile. 
     Referring to  FIG. 2 , the reaction chamber  18  comprises a high power supply unit when atmospheric-pressure plasma is used in for the plasma-treatment of the textile product  24 . The reaction chamber  18  is set to operate at 300 W. The electrodes  20  employed within the reaction chamber  18  are made of ceramic containing aluminum oxide (Al 2 O 3 ) essentially. An alternating current of 20 kV is supplied to the electrodes  20 , as a result of which, a substantial amount of heat is generated by the electrodes  20  during the course of the plasma-treatment. An oil circulation system operated by a pump is employed for cooling the electrodes  20  at regular intervals in order to help prevent the same from overheating. 
     The distance between the electrodes  20  is adjustable within a range of 0.5 to 2.5 mm. Nitrogen is preferable although air and other gases including oxygen, argon can also be used for generating plasma. The reaction chamber  18  further comprises a trolley  22  whereon the textile product  24  is placed for uniform plasma exposure. More particularly, a vacuum sucker is employed for holding the textile product  24  in place as the trolley  22  imparts linear movement to the textile product. In one embodiment, a plurality of guide rolls is employed instead of the trolley  22  for transporting the textile product through the reaction chamber  18 . 
     Apart from the plasma produced from the ceramic electrodes  20 , a precursor material  26  is discharged into the plasma medium. The state of matter of the precursor material  26  may be liquid or powered. The precursor material  26  is atomized as the same is released into the plasma thereby enabling precursor material  26  to uniformly mix with the plasma. 
     N—H groups are formed over the surface of the textile product as the same is subjected nitrogen plasma mixed with the precursor material. The N—H functional groups cause the textile product exhibit antimicrobial property, anti-creasing property, anti-soiling property, UV protective property, and so on. The Limited Oxygen Index (LOI) of the finished multifunctional textile is substantially more than that of the textile product and hence, the multifunctional textile is highly fire and flame-retardant. Also, the UV Protection Factor (UPF) of the finished multifunctional textile is nearly 2000 thus making it highly protective against UV radiation. The multifunctional textile can be used for filtering metals from wastewater. Compared to the input textile product, the dyeability of the finished multifunctional textile is substantially higher. 
     In both the cases of low-pressure plasma and atmospheric pressure plasma, the time of exposure of the plasma is not more than 5 minutes. However, the exposure time may vary depending on the plasma, the purity of gas, the textile product and its shape, and so on. The finished multifunctional textiles are antimicrobial, wrinkle-free, breathable, fire and flame-resistant, water-proof, UV-protective, dyeable, EMI shielding, oil repellant, and so on. The multifunctional textile exhibits anti-soiling function when the surface thereof is added with a layer of titanium oxide nanoparticles. 
     The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims. 
     Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall therebetween.