COTTON FABRIC

FIELD OF THE INVENTION

[0001] The present invention relates to a method and system for manufacturing multifunctional cotton fabric.

BACKGROUND OF THE INVENTION

[0002] Due to the changing environment in the last few years, there is increase in concern over damage caused by exposure to microbes, chemical, pesticides, UV rays and pollutants. Such concern has boosted the demand for protective garments. Accordingly, nowadays clothing is expected to be waterproof, flame retardant, self cleaning, insect repellent and antimicrobial to protect the human beings from infection, UV light, chemical and biological agents.

[0003] Single functional and dual functional fabrics have been available for a long time. Such fabrics were conventionally developed by pad- dry-cure or coating technique. However, such finished fabrics are unable to meet the desired properties and comfort level. Furthermore, the components used for finishing these conventional fabrics are not eco-friendly.

[0004] Further, the conventional methods of finishing fabrics, such as pad-dry-cure or coating that are currently being used to impart antimicrobial, anti UV rays, self cleaning and flame retardant finishes, are often accompanied by excessive weight add on, loss of feel and drape, poor durability to washing, loss of mechanical strength and most importantly reduced comfort to wearer.

[0005] Accordingly, there is a need for a method and system to manufacture a multifunctional fabric that provides protection against UV rays, pollutants, microbes, flames and is self cleaning; while not compromising on durability, mechanical strength and comfort to wearer. Further, what is required is an eco-friendly method and system for manufacturing multifunctional fabrics which possess a good durability to washing, a good mechanical strength and is of normal weight for comfort to the wearer.

SUMMARY OF THE INVENTION

[0006] To achieve the foregoing and other objects and needs, the present invention provides a method and system for manufacturing multifunctional cotton fabric incorporating the multiple functionalities of UV protection, flame retardancy, anti-bacterial properties and easy care finish; while not compromising on durability, mechanical strength and comfort to wearer.

[0007] In one aspect, the present invention provides a method for manufacturing multifunctional cotton fabric. The method comprises: treating a cotton fabric with atmospheric pressure plasma dielectric barrier discharge (DBD) at predefined parameters to form a plasma treated cotton fabric; preparing a nano particle finishing bath solution; performing padding by applying nano particle finishing bath solution on plasma treated cotton fabric to form a padded cotton fabric; performing drying on padded cotton fabric to form a dried padded cotton fabric; performing curing on dried padded cotton fabric to form a finished fabric; and performing a plasma polymer deposition on the finished fabric to form the multifunctional cotton fabric.

[0008] In another aspect, the present invention provides a system for manufacturing multifunctional cotton fabric. The system comprises a plasma treatment unit capable of treating a cotton fabric with atmospheric pressure plasma dielectric barrier discharge (DBD) at predefined parameters to form a plasma treated cotton fabric; a nano particle finishing bath solution capable of performing padding by applying nano particle finishing bath solution on plasma treated cotton fabric to form a padded cotton fabric; a drying unit capable of performing drying on padded cotton fabric to form a dried padded cotton fabric; a curing unit capable of performing curing on dried padded cotton fabric to form a finished fabric; and a plasma polymer deposition unit capable of performing a plasma polymer deposition on the finished fabric to form the multifunctional cotton fabric. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The advantages and features of the present invention will become better understood with reference to the following detailed description and claims taken in conjunction with the accompanying drawing,, in which:

[0010] FIG. 1 illustrates a method flow for manufacturing multifunctional cotton fabric, in accordance with an exemplary embodiment of the present invention;

[001 1] FIG. 2 illustrates details of a system used for manufacturing multifunctional cotton fabric of method of FIG. 1 ; and

[0012] FIGS. 3A, 3B, 3C and 3D illustrate comparative studies of the properties of the different samples of multifunctional cotton fabrics.

DETAILED DESCRIPTION OF THE INVENTION

[0013] The exemplary embodiments described herein detail for illustrative purposes are subject to many variations in structure and design. It should be emphasized, however, that the present invention is not limited the method and system for manufacturing multifunctional cotton fabric, as shown and described. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but these are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0014] The use of terms "including," "comprising^" or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Further, the terms, "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. [0015] The present invention provides a method and system for manufacturing multifunctional cotton fabric (hereinafter referred to as method). Specifically, the present invention provides a method and system for processing cotton fabric to develop the multifunctional cotton fabric to incorporate the functionalities including UV ray protection, flame retardancy, antibacterial ,easy care finish and water repellent. The method of the present invention provides for an improved performance of the finished goods while minimizing the use of components as eco-friendly method. The method of the present invention employs: performing a plasma treatment directly on cotton fabric and treatment of the cotton fabric with nano particles.

[0016] As used herein UV ray refers to electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays. The toxic effects of UV rays from natural sunlight are a major concern for human health. Some of the primary effects of UV irradiation on normal human skin comprise sunburn inflammation erythema, tanning, and local or systemic immunosuppression. UV radiations can contribute to skin cancer via indirect DNA damage. Further, as used herein, "UV protection" refers to protection against the harmful effects of the UV ray.

[0017] As used herein, "flame retardancy" refers to inhibiting, suppressing, or delaying the production of flames to prevent and/or minimize the spread of fire.

[0018] As used herein, "antibacterial properties" refer to the activity which is against bacteria. Specifically, antibacterial is an agent that interferes with the growth and reproduction of bacteria. Further, antibacterial agents used to disinfect surfaces and eliminate potentially harmful bacteria.

[0019] As used herein, "easy care finish" refers to the fabric that have been treated with specific carboxylic acids that cross-link upon processing to provide an advantageous durable finish, dependent upon the resin used, various properties can be achieved such as crease recover, wrinkle resistance & recovery, shrink resistance and also reduced requirements for ironing or enhanced / easier to iron garments.

[0020] As used herein, "water repellent" refers to feature of the fabric wherein the fabric becomes water-resistant (or hydrophobic). [0021] In one embodiment, the plasma treatment in fabric refers to the application of plasma technology in chemical processing of fabrics. Plasma treatment is a simple process which could be easily automated and has perfect parameter control. Plasma treatment is applicable to most of textile materials for surface treatment. Plasma

technologies have been used in fabric materials, resulting in improvements to fabric products. It can improve the functionality of fabric materials such as: improved pretreatment process, improved dyeing and printing, hydrophobic finishing, product quality, adhesion and the like.

[0022] In one embodiment, the nano technology in fabric refers to a nano fibers at the atomic and molecular levels in order to improve the properties of fabric. Nano technology can give rise to incredible clothing such as water-resistant and dirt-free clothes, odor-less socks, and intelligent clothes that can perform climate control. Further use of nano technology enhance the surface characteristics of clothes such as water/stain-resistance, UV protection, wrinkle resistance, color durability, flame retardancy, and better thermal performance.

[0023] In one embodiment, the method for manufacturing multifunctional cotton fabric comprises: plasma treating a cotton fabric with atmospheric pressure plasma dielectric barrier discharge (DBD) at predefined parameters to form a plasma treated cotton fabric; preparing a nano particle finishing bath solution; performing padding by applying nano particle finishing bath solution on plasma treated cotton fabric to form a padded cotton fabric; performing drying on padded cotton fabric to form a dried padded cotton fabric; performing curing on dried padded cotton fabric to form a finished fabric; and performing a plasma polymer deposition on the finished fabric to form the multifunctional cotton fabric.

[0024] The steps of the method 100 are described with reference to FIG. 1. In FIG. 2, the details of the system 200 are illustrated for performing the steps of method 100 of FIG. 1. In the below description, the method 100 and the system 200 are collectively described; and the reference numerals are used individually and/or collectively from one or more of the FIGS. 1-2.

[0025] Referring to FIG. 1 , at step 102, the method 100 initiates by plasma treating a cotton fabric with atmospheric pressure plasma dielectric barrier discharge (DBD) at predefined parameters to form a plasma treated cotton fabric. Specifically, referring to 202, 204 and 206 of FIG. 2, the plasma treated cotton fabric is formed by treating a ready for dyeing (RFD) cotton fabric coming from cotton fabric roll 202 with atmospheric pressure plasma dielectric barrier discharge (DBD) at a plasma treatment unit 204 at predefined parameters to form a plasma treated cotton fabric 206.

[0026] As used herein, DBD is the electrical discharge between two electrodes separated by an insulating dielectric barrier which can be used to generate optical radiation by the relaxation of excited species in the plasma.

[0027] The predefined parameters of plasma treatment of DBD atmospheric pressure plasma comprises: a gas composition of 5 litres per minute (1pm) of helium and a 0.5 1pm of oxygen; a plasma discharge power of 2.5 Kilo watt (Kw); a distance between electrodes of 0.5 millimetre (mm); and a plasma exposure time of 1 minute.

[0028] Now referring again to FIG. 1, at step 104, the method 100 comprises preparing a nano particle finishing bath solution. Specifically, referring to 208 of FIG. 2, the nano particle finishing bath solution 208 is formed by mixing at least one of nano Ti0 ₂ and nano ZnO; and at least one of a cross linking agent and a phosphorous compound. In one embodiment, the nano particle finishing bath solution comprises: about 0.5 to about 1.5 percent of at least one of nano Ti0 ₂ and nano ZnO; and about 4 to about 8 percent of at least one of a cross linking agent and a phosphorous compound.

[0029] As used herein, the cross linking agent, in one embodiment is butanetetracarboxylic acid (BTCA). BTCA is a perfect formaldehyde-free durable press (DP) finishing agent. It has high activity of reaction and no irritant odor. Processed by BTCA, fabrics such as cotton and silk can achieve properties including anti-cease, permanent press and keeping shape and are of high tenacity. The fabric quality can reach the accomplishment of traditional DP finishing agent with formaldehyde and liquid ammonia. Furthermore, the technique is simple and has no pollution. Therefore, BTCA is a perfect substitute for DP finishing agent of formaldehyde. In addition, BTCA can be used in manufacturing polyimide (PI) materials which has heat-proof, acid-proof and hydrocarbon- proof properties, used in manufacturing functional polymer materials such as photosensitive materials, biomedical materials and functional polymeric membrane materials. [0030] As used herein phosphorous compound is sodium hypophosphite

(SHP) also known as sodium phosphinate is the sodium salt of hypophosphorous acid and is often encountered as the monohydrate, NaPChft ftO. It is a solid at room temperature, appearing as odorless white crystals. Specifically, SHP is used in fabrics to increase the Limiting Oxygen Index of the fabric.

[0031 ] In table 1 below, different concentration of components are mentioned that are used to prepare nano particle finishing bath solution.

TABLE 1

[0032] Now referring again to FIG. 1, at step 106, the method 100 comprises performing padding by applying nano particle finishing bath solution on plasma treated cotton fabric to form a padded cotton fabric. Specifically, referring to 206, 208, 210 and 212 of FIG. 2, padding is performed by applying nano particle finishing bath solution 208 on plasma treated cotton fabric 206 and thereafter squeezed with squeezing rollers to form the padded cotton fabric 212. The padding of the plasma treated cotton fabric 206 is done with pick up percent which is at least 100 percent. [0033] As used herein pick up: percent refers to the weight add on the plasma treated cotton fabric 206 after padding and squeezing as illustrated in FIG. 2. Further 100 percent pick up signifies that the weight of the padded cotton fabric 212 obtained after padding and squeezing of the plasma treated cotton fabric 206 is double the weight of the plasma treated cotton fabric 206.

[0034] Now referring again to FIG. 1, at step 108, the method 100 comprises performing drying on padded cotton fabric to form a dried padded cotton fabric. Specifically, referring to 212, 214 and 216 of FIG. 2, dried padded cotton fabric is formed by drying the padded cotton fabric 212 at 85°C at a drying unit 214 comprising fabric holder for at least 5 minutes to form dried padded cotton fabric 216. Further, as used in the present invention, drier unit may be obtained from Spooner.

[0035] Now referring again to FIG. 1, at step 110, the method 100 comprises performing curing on dried padded cotton fabric to form a finished fabric. Specifically, referring to 216, 218 and 220 of FIG. 2, finishing of fabric is performed by curing the dried padded cotton fabric 216 at 180°C at a curing unit 218 for at least 2 minutes to form finished fabric 220.

[0036] .As used herein, curing refers to process that follows the addition of a finish to a fabric and in which appropriate conditions are used to effect a chemical reaction.

[0037] Now referring again to FIG. 1, at step 112, the method 100 comprises performing a plasma polymer deposition on the finished fabric to form the multifunctional cotton fabric. Specifically, referring to 220, 222 and 224 of FIG. 2, the multifunctional cotton fabric 224 is formed by depositing hexamethyldisiloxane (HMDSO) polymer on the finished fabric 220 in DBD atmospheric pressure plasma at a plasma polymer deposition unit 222 at predefined parameters.

[0038] As used herein hexamethyldisiloxane (HMDSO) polymer is a monomer. Further, the HMDSO is an organosilicon compound with the formula 0[Si(CH ₃ ) ₃ ]2. This volatile colourless liquid is used as a solvent and as a reagent in organic synthesis. It is prepared by the hydrolysis of trimethylsilyl chloride. The molecule is the protypical disiloxane and resembles a subunit of polydimethylsiloxane. Further, the HMDSO plasma polymer treated fabric gives the excellent water repellency. [0039] The predefined parameters of atmospheric pressure plasma dielectric barrier discharge (DBD) to form multifunctional cotton fabric comprises: a gas composition of 5 litres per minute (1pm) of helium; a plasma discharge power of 3.5 Kilo watt (Kw); a distance between electrodes of 0.5 millimetre (mm); a plasma exposure time of 30 seconds, 1 minute, 2 minutes and 4 minutes; and a flow rate of hexamethyldisiloxane (HMDSO) polymer on the finished fabric 220 of lml/min.

[0040] As the hexamethyldisiloxane (HMDSO) polymer which is a silicon containg monomer, the multifunctional cotton fabric formed at step 1 10 of the method of 100 of FIG. 1 becomes hydrophobic and gives the excellent water repellency and is further durable to washing. As used herein water repellency is measured as contact angle which is 135° and spray rate of 80.

RESULTS

[0041] The multifunctional cotton fabric formed by the method described above in FIG. 1 can be developed without use of plasma treatments. In comparative study of the cotton fabric finished with plasma treatment and without plasma treatment, it was found that the cotton fabric formed by plasma treatment requires chemical concentration of the nano particle finishing bath solution which can be lower by 20-25 %. Hence the cotton fabric formed by plasma treatment can reduce the final cost of the multifunctional cotton fabric compared to the multifunctional cotton fabric formed without use of plasma treatments.

[0042] In table 2, different concentration of components to prepare nano particle finishing bath solution and the properties of the multifunctional cotton fabric formed with plasma treatment and without plasma treatment is described.

TABLE 2

ZnO (UPF) Retardancy (CRA angle )

(LOI)

Plasma WOP Plasma WOP plasma WOP plasma WOP

0.5 4 66.1 43.6 P AB 22.4 21 267 246

0.5 6 53.7 51.1 P AB 23.9 22.1 276 257

0.5 8 48.7 47.8 P AB 26.2 24.1 296 267

1 4 89.3 76.2 P P 26.7 24.7 271 258

1 6 74.8 72.7 P P 28 26.8 282 271

1 8 76 71.5 P P 30.7 27.5 306 276

1.5 4 . 122.5 119.3 P P 26.8 24.1 240 230

1.5 6 1 19 97.9 P P 28 26.9 259 250

1.5 8 96.1 89.8 P P 30.8 28.1 286 270

[0043] As used in table 2, WOP refers to processing of cotton fabric without plasma treatment.

[0044] As used in table 2, P refers to presence of antibacterial feature in the multifunctional cotton fabric.

[0045] As used in table 2, AB refers to absence of antibacterial feature in the multifunctional cotton fabric.

[0046] As used in table 2, UPF refers to UV Protection Factor which is used for rating designation for sun protective textiles and clothing. UPF measures both UV radiation transmittance using a laboratory instrument and an artificial light source and translates these results using a mathematical expression based upon the sunburn action spectrum (erythema action spectrum) integrated over the relevant UV spectrum. UPF rating from about 40 to about 50 plus is considered to be excellent UV protection category which can block about 97.5% to about 99% of UV radiation.

[0047] As used in table 2, LOI refers to Limiting Oxygen Index which is the minimum percentage of oxygen it takes in an air-like gas mixture to support flaming combustion. The LOI is a method of ranking the polymers based on combustibility. This property is very important for plastics used in aviation. As the normal amount of oxygen in air is approximately 21%, polymers with indexes below 21 will burn continuously at normal conditions. The LOI is measured by placing the samples in a flow of oxygen/nitrogen gas and increasing the concentration of oxygen until the sample will support combustion. The next lowest oxygen concentration is the value used as the index.

[0048] As used in table 2, CRA angle refers to measurement of creases resistance in the textiles.

[0049] As described in table 2, it can be seen that cotton fabric formed by plasma treatment requires chemical concentration which can be lower by 20-25 %. Hence the cotton fabric formed by plasma treatment can reduce the final cost of the multifunctional cotton fabric compared to the multifunctional cotton fabric formed without use of plasma treatments. Further, it can be seen that the concentration of components to prepare nano particle finishing bath solution and the properties of the multifunctional cotton fabric prepared at serial number 5 (plasma treated) as mentioned in table 2 shows better results as compared to the multifunctional cotton fabric prepared at serial number 6 (without plasma treatment). Accordingly, it can be inferred that use of plasma technology can lower down the required concentration of components for better performance than that of the required concentration of components used without plasma treatment.

[0050] Further, table 3 below describes the comparative studies between 2 different samples of plasma treated and without plasma treated multifunctional cotton fabric. It can be seen from the table 3 that for the sample 2 (plasma treated) the chemical concentration of the nano particle finishing bath solution can be reduced by 2%. The comparison of those samples was made on the basis of their performance properties. Further, FIGS. 3 A, 3B, 3C and 3D shows UPF graph, CRA graph, LOI graph and 45° flammability graph respectively for the two samples described in the table 3 below.

TABLE 3

T1O2/ ZnO 1% 1%

BTCA /SHP 8% 6%

[0051] By referring to FIGS. 3 A, 3B, 3C, 3D and Table 3, it can be easily seen that sample 1 has enhanced UV protection, enhanced CRA, and enhanced flame retardancy as compared to "control cotton fabric". Further, sample 2 with plasma treatment has enhanced UV protection, enhanced CRA, and enhanced flame retardancy as compared to "control cotton fabric" and sample 1.

[0052] Without in any way limiting the scope, interpretation, or application of the claims appearing below, advantages of one or more of the exemplary embodiments disclosed herein provides an application of plasma technology in cotton fabric is for modification of the surface properties of the cotton fabric without affecting the bulk (desired) properties. As used herein, plasma technology is used for surface activation of the cotton fabric, so that some reactive groups, free radicals are present of the cotton fabric which improved the reactivity of the cotton fabric with given nano materials. The main purpose of use of plasma is to create reactive sides on the cotton fabric surface which are helpful in the subsequent processing.

[0053] The foregoing descriptions of specific embodiments of the present disclosure have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present disclosure and its practical application, to thereby enable others skilled in the art to best utilize the present disclosure and various embodiments with various modifications as are suited to the particular use contemplated. (It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present disclosure).