DESC:DETAILED DESCRIPTION
The following description and example illustrate some exemplary embodiments of the disclosed invention in detail. Those of skill in the art will recognize that there are numerous variations and modifications of this invention that are encompassed by its scope. Accordingly, the description of a certain exemplary embodiment should not be deemed to limit the scope of the present invention.

The term “comprising” as used herein is synonymous with “including,” or “containing,” and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.

All numbers expressing quantities of ingredients, property measurements, and so forth used in the specification are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth herein are approximations that may vary depending upon the desired properties sought to be obtained.

Textile or fabrics are made from yarns which are woven or knitted to form the fabric. The yarn is typically formed by spinning fibres or twisting fibres together, and the fibres could be of natural origin, or man-made or any combinations thereof. The properties of the textile depend on the characteristics of the fibres or yarns from which they are made.

One important characteristic of the yarn is the length of fibre from which they are prepared. A fluffy, spongy yarn is obtained from shorter fibres, where many loose ends remain disoriented in the yarn. Fibres with longer lengths give smoother, finer yarns with a higher lustre and higher strength and a finer textile.

Strength is also one of the important characteristics of a textile fibre. The individual fibres must have sufficient strength to withstand mechanical strain during processing to form the textile. The resistance of a fibre to use and wear is considerably dependent on its tensile strength. The strength of any material is derived from the load it supports at break and is thus a measure of its limiting load bearing capacity. The term “breaking strength” of a fibre, as used herein, is defined as the maximum amount of tensile stress that the fibre can withstand before breaking or deformation. Higher breaking strength indicates higher strength of the fibre which is desirable for good quality textile.

Fabric softness is one of the most frequently used terms in describing clothing comfort performance by consumers. A smooth fabric is the one that offers little frictional resistance to motion across its surface and possesses a low coefficient of friction. Fabric softness can be related to compression and/or to smoothness or fineness and flexibility of fibres it is made from. The term “linear density”, is a measure of the mass per unit length of a fibre, and can be related to measure of fineness. The term “Denier”, is the unit of linear density.

Embodiments of the present invention provides a textile-grade fibre derived from agricultural waste fibre. The agricultural waste fibre may be derived from agricultural waste including stems, leaves or pseudo stems of plants.

In one embodiment of the invention, the textile-grade fibre is derived from an agricultural waste fibre, wherein the textile grade fibre has a breaking strength in a range of 10 grams (g) to 90 g and a length in the range of 15 millimeters (mm) to 150 mm.

The agricultural waste fibre is a coarse agricultural waste fibre, or a fine agricultural waste fibre, or any combinations thereof. The characteristics of the textile-grade fibre so produced will vary depending on the agricultural waste fibre it is derived from. The term “coarse agricultural waste fibre” as used herein, refers to agricultural waste fibre marked by larger diameter and longer length when compared to “fine agricultural waste fibre”. The coarse agricultural waste fibre is suitable for making textile-grade fibre that may be used to produce home furnishings, ropes and other technical textiles. The fibres that are separated from bast plants may fall under the category of coarse agricultural waste fibres due its characteristics such as coarseness and much longer fibre length as compared to the fine agricultural waste fibre. A “bast fibre”, as used herein, refers to fibres obtained from outer cell layers of stems of various plants. In plants, the bast fibres are located between the epidermis, or bark surface and an inner woody core, as fibre bundles. Each fibre in a bundle is connected by a gummy substance comprising pectin. The bast fibres are often several feet long and are composed of cellulose, hemicellulose and lignin. In one embodiment, the coarse agricultural waste fibre is derived from agricultural waste of paddy straw, banana stem, wheat straw, kenaf, maize jute, or any combinations thereof. When the textile-grade fibre is derived from the coarse agricultural waste fibre, the textile-grade fibre so produced has a linear density in the range of 40 denier to 55 denier. The textile-grade fibre derived from the coarse agricultural waste fibre has a breaking strength in the range of 70 grams (g) to 90 g. The length of the textile-grade fibre derived from the coarse agricultural waste fibre is in the range of 20 millimeters (mm) to 150 mm.

The fine agricultural waste fibre is derived from agricultural waste of food crops such as pineapple, centre part of banana leaves, linseed, oilseed hemp, nettle, hemp, bamboo, flax, ramie or any combinations thereof. When the textile-grade fibre is derived from the fine agricultural waste fibre, the textile-grade fibre has a linear density in the range of 3 denier to 7 denier. The textile-grade fibre derived from the fine agricultural waste fibre has a breaking strength in the range of 10 grams (g) to 30 g. The length of the textile-grade fibre derived from the fine agricultural waste fibre is in the range of 15 millimeters (mm) to 100 mm.
Embodiments of the present disclosure provides a method for producing textile-grade fibre from agricultural waste fibre. The agricultural waste is sourced from different plants and/or plant parts and are processed to obtain the agricultural waste fibre. The processing steps will be different for each type of agricultural waste. At the first stage, the agricultural waste is separated from foreign matter and other non-fibrous plant parts. This may be achieved by manual separation by hand which is time-consuming or by use of machines such as blowers and sievers. In the case of pineapple leaves, the leaves are mechanically opened and the fibrous material is separated from other components of the leaf to obtain the agricultural waste fibre. In the case of banana stem, the stems are cut longitudinally and the liquid inside is drained out and the fibrous material is pulled out to obtain the agricultural waste fibre.

A particular advantage of the method is that the production method of the textile-grade fibre is applicable for any agricultural waste fibre irrespective of the source of its origin. The method for producing textile-grade fibre from agricultural waste fibre comprises mechanically sorting the agricultural waste fibre to form a sorted fibre having uniform length. The agricultural waste fibre is processed through a roller or series of rollers to separate fibres according to their length thus obtaining fibres of uniform length. During mechanical sorting, other plant parts, such as the bark and inner woody core which has remained, are removed. In one embodiment, mechanically sorting the agricultural waste fibre comprises taking the agricultural waste fibre through a roller comprising a feed roller, or a spike roller, or both to form the sorted fibre. The feed rollers are blunt round rollers with small cuts that presses the fibre bundle to remove woody or leafy part from the fibrous part. The spike rollers are round rollers with spikes or pins that help in opening or combing the fibre bundle leading to breaking the fibre bundle and obtaining fibres oriented parallelly.

At the next step, the sorted fibre is chemically treated with an alkali mixture to form an alkali-treated fibre. In one embodiment, the alkali mixture comprises an alkali and a silicone mixture. Suitable alkali includes sodium hydroxide, potassium hydroxide or any combinations thereof. The “alkali”, as used herein, refers to sodium hydroxide or potassium hydroxide present in water or an aqueous solution at concentrations of 48% to 50%. The alkali is added in an amount of 5% to 8% by weight to the total weight of the mixture containing the sorted fibre and alkali mixture.

The silicone mixture comprises a silicone polymer having siloxane functional groups. Hereinafter, the “silicone polymer” is also otherwise termed as a “silicone”. The silicone polymers include straight chain dimethylsiloxane (dimethicone) polymers, or cyclic dimethicone polymers or any derivatives thereof. In one embodiment, the silicone polymer is polydimethylsiloxane. In certain embodiments, the silicone mixture comprises silica nanoparticles along with the silicone polymer. The silica nanoparticles may be a modified silica nanoparticle having varying hydrophobicity or hydrophilicity so as to complement the action of silicone polymer in the alkali mixture.

The silicone mixture is present in an amount of 0.5% to 2% by weight to the total weight of the mixture containing the sorted fibre and the alkali mixture. In one embodiment, the alkali is present in an amount of 5% to 8% by weight to the total weight and the silicone mixture is present in a range of about 0.5% to 2% by weight to the total weight.

The concentration of alkali in the mixture, time of alkali treatment and temperature is optimized to obtain the alkali treated-fibre. For example, a high alkali concentration may cause an excess elimination of waxy covering of the cellulose surface and delignify the fibre, which can negatively impact the strength of the fibre. The sorted fibre is exposed to the alkali mixture for a time period of up to 2 hours, at a temperature in a range of 85? to 100?.

According to embodiments of the invention, the silicone mixture is provided in the alkali mixture for alkali treatment of the sorted fibre. The silicone polymer of the silicone mixture advantageously enhances the action of the alkali as a result of which a material to liquor ratio is lowered. In one embodiment, the alkali treatment is performed at a MLR ratio of 1:5. As used herein, the term “material to liquor ratio” (MLR) refers to ratio of the weight of the sorted fibre to the weight of water required for the process. It is desirable to have a lower MLR ratio as it reduces the amount of water used for processing. This also translates to considerable energy savings as the alkali treatment is typically performed at elevated temperatures (above 85?). As compared to existing methods, having higher MLR ratio of the order of 1:10 or more, the addition of the silicone lowers the amount of water required for processing thus enhancing the sustainability in terms of energy savings and water requirement for the whole process.

During alkali treatment, the structure of a surface of the sorted fibre is modified by alkali. It is known that the alkali treatment of natural fibres diminishes moisture-related hydroxyl groups and thus reduces the hydrophilic nature of the fibres. Additionally, alkali treatment removes hemicellulose, lignin, pectin, wax and oil coverings from the surface of sorted fibre thus retaining fibrous part. Pectin is generally insoluble in water or acid, but breaks down on alkali treatment. After alkali treatment, surfaces of the fibres become rougher resulting in a decrease in diameter with an increment in aspect ratio and improvement in the mechanical strength of the fibre.

At the next step, the alkali-treated fibre is dried to form a dried fibre. During this step, the water from earlier processing is removed from the fibre. In one embodiment, the drying is performed by hydroextraction in an hydroextractor. Any suitable hydroextractor may be utilized. The hydroextraction is followed by drying in an oven. In yet another embodiment, the alkali-treated fibre is dried under sun. Sun drying is preferred from sustainability and from a cost perspective, however it is time-consuming.

At the next step, the dried fibre is exposed to a softening composition to obtain the textile-grade fibre. In one embodiment, the softening composition comprises an enzyme, a polymer, a vegetable oil and water in the ratio of 1:1:1:7 by weight. The vegetable oil is selected from a group of castor oil, palm oil or any blends thereof.
Suitable enzymes include pectinases, xylanases or any combinations thereof. Example pectinases include enzymes that can hydrolyse pectic-substances such as pectin. Pectinases are a group of enzymes that hydrolyse glycosidic linkages of pectic substances mainly poly-1, 4-alpha-D- galacturonide and its derivatives. The term "pectinase" includes any acid pectinase enzymes. The enzyme is understood to include a mature protein or a precursor form thereof, or a functional fragment thereof, which essentially has the activity of the enzyme. Furthermore, the term pectinase enzyme is intended to include homologues or analogues of such enzymes. Pectinases can be mainly endo-acting, cutting the polymer at random sites within the chain to give a mixture of oligomers, or they may be exo-acting, attacking from one end of the polymer and producing monomers or dimers. Suitable pectinase includes pectate lyase (EC 4.2.2.2), pectin lyase (EC 4.2.2.10), polygalacturonase (EC 3.2.1.15), exo-polygalacturonase (EC 3.2.1.67), exo- polygalacturonate lyase (EC 4.2.2.9) and exo-poly-alpha-galacturonosidase (EC 3.2.1.82). In one embodiment, the pectinase is Palcascour™ with pectin activity E2.
As used herein, the term xylanase" or "xylanases", refer to an enzyme capable of depolymerizing plant cell component xylan. Suitable xylanases include 1--> 4)-beta-xylan 4-xylanohydrolase (EC 3.2.1.8), b-d- xylosidases (E.C. 3.2.1.37), a-glucuronidase (EC 3.2.1.139), acetylxylan esterase (EC 3.1.1.72), a-1-arabinofuranosidases (E.C. 3.2.1.55), p-coumaric esterase (3.1.1.B10) and ferulic acid esterase (EC 3.1.1.73).

The vegetable oil enhances lubrication between various components of reaction mixture, such as non-hydrolyzable matter that is present in alkali-treated fibre or non-hydrolyzable matter produced during softening step, especially pectin and/or lignin that is released during this step. Further, the vegetable oil may reduce entanglement by lowering friction between fibre material and further soften the fibre. The vegetable oil is selected from a group of castor oil, palm oil and any blends thereof.

The polymer is a copolymer of ethylene oxide (EO), or propylene oxide (PO) or a combination of ethylene oxide and propylene oxide with a fatty alcohol with a minimum number average molecular weight of 1000 amu. Suitable fatty alcohols include those containing 8 to 18 carbon atoms and may be saturated or unsaturated; linear or branched. Example such fatty alcohols include, but are not limited to, capryl alcohol, palmitoleyl alcohol, 2-propylheptanol, tridecyl alcohol, myristyl alcohol, lauryl alcohol, stearyl alcohol, and oleyl alcohol. In one embodiment, the polymer is a copolymer of ethylene oxide, propylene oxide and 2-propylheptanol. In the softening step, the dried fibre is exposed to the softening composition at a softening composition to dried fibre ratio of 3:20 for a time period of up to 24 hours to obtain the textile-grade fibre. In one embodiment, exposing the softening composition comprises spraying the dried fibre with the softening composition.

The term “softening composition”, as used herein, refers to chemicals or a blend of chemicals when applied to fibre brings about a change whereby the fibre becomes softer and much more pleasing to touch. The softening composition may have certain other desirable properties such as antistatic property, elasticity, abrasion resistance, hydrophilicity, and moisture regulation properties. It is believed that the softening action is due to favourable electrostatic interaction between components of softening composition and the surface of the fibre. Due to favourable electrostatic interactions, the components of the softening composition may orient on the surface of the fibre thus enhancing softness and some may penetrate the fibre causing a plasticizing action of the fibre and reducing its glass transition temperature.

The softening composition of the present disclosure can be used to soften fibre derived from agricultural waste fibre. Without any limitation, one can utilize the softening composition of the present disclosure in similar such processes to soften fibres derived from agricultural waste fibre in the production of textile-grade fibre.

The textile-grade fibre obtained is tested for various properties so as to find its suitability as textile-grade fibre. The non-limiting examples of such properties include fibre length, breaking strength and linear density.

The textile-grade fibre is converted to yarns by spinning or twisting it together. The yarns so formed can be processed in existing cotton yarn processing units for further processing. The yarn is converted to fabric or textiles by weaving or knitting the yarns. In weaving, two sets of yarns weft and wasp are interlaced at right angles to each other to form the textile.

The textile-grade fibre and methods for making the same of the present invention are sustainable with considerable water savings and energy savings. The method is advantageous as it converts agricultural waste to textile-grade fibre and prevents burning of agricultural waste and at the same time has potential to enhance the income of small farmers. Further, the textile-grade fibre so obtained is naturally anti-microbial and exhibits beneficial cotton-like properties.

EXAMPLES
Comparative Example 1:
An agricultural waste fibre sample was exposed to an alkali mixture containing sodium hydroxide but without any silicone. The percentage of sodium hydroxide used was 9 % and the mixture was heated at 85? to 100 ? for two hours. A MLR ratio of 1:10 was required to obtain the alkali-treated fibre.

Example 1:
An agricultural waste fibre sample was exposed to an alkali mixture containing sodium hydroxide (NaOH) and a silicone mixture comprising polydimethylsiloxane and silica nanoparticles. The percentage of NaOH used was 6 % and the mixture was heated at 85? to 100 ? for two hours. A MLR ratio of 1:5 was utilized to get the alkali-treated fibre. As compared to the Comparative Example 1, the amount of alkali was reduced and the amount of water was reduced by half due to the presence of silicone in the alkali mixture.

Example 2:
A dried fibre obtained after drying of alkali-treated fibre of Example 1 was subjected to softening using various softening compositions, such as castor oil, copolymer of ethylene oxide, propylene oxide with 2-propyl heptanol (polymer) and Palcoscour™ (pectinase). To evaluate the effect of each component of the softening composition a series of experiments were conducted with each of the components as well as combinations of these to arrive at the most effective softening composition as shown in Table 1.

Table 1: varying compositions of softening compositions
Experiment No. Softening composition
Observations
1. Castor Oil in 6 weight% ratio to fibre weight Fibre surface was slippery but overall softness was low. Also, there was no effect on lignin/pectin content leading to difficulties in spinning process.
2. polymer in 6 weight% ratio to fibre weight Fibre was soft but fibre weight had increased. No effect on lignin/pectin content leading to difficulties in spinning process. Yellowish tinge on the fibre which was not desirable.
3. Palcoscour™ in 6 weight% ratio to fibre weight lignin/pectin was reduced. Uneven softness in fibre, as some parts are soft and some were not. Time required for softening was high requiring 72 hours or more. Cost is very high.
4. Combination of polymer and Palcoscour™ Fibre was soft but no effect on lignin/pectin content
5 Combination of castor oil and Palcoscour™ Problem of uneven softness persists. The time required for softening process was high requiring 48 to 60 hours. Cost is high
6 1 part castor oil, 1 part polymer, 1part Palcoscour™ and 7 parts distilled water in 5 weight % ratio to fibre weight Obtained best result. Softness was even. Fibre weight was lower indicating better removal of pectin/lignin. Time required was lower than required for Experiments 1 to 5

The textile-grade fibre obtained after softening using the softening composition, as mentioned in experiment 6, were tested for linear density, breaking strength and length. Two sets of textile-grade fibres were tested, first set derived from oilseed hemp corresponding to fine agricultural waste fibre and second set of agricultural waste fibre derived from wheat straw corresponding to coarse agricultural waste fibre. The linear density was measured using ASTM D177 (RA2018): 2007/IS 234:2013 test method. ASTMD5103:2007 (RA2018) test method was used to measure the length of the fibre and SD corresponds to Standard Deviation. The breaking strength of single fibre was measured using ASTM D 3822-07 (2014) test method. Table 2 shows the test values of the two sets of agricultural waste fibre.

Table 2
Length of the fibre (mm) Breaking strength (g) Average Linear density (Denier)
Fine agricultural waste fibre 38 (SD: 9.2) 20.91 5.65
Coarse agricultural waste fibre 53 (SD: 18.7) 82.77 45.69

While various embodiments of the disclosure have been illustrated and described, it will be clear that the disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the scope of the disclosure, as described in the claims of the complete specification.
,CLAIMS:1. A method for producing textile-grade fibre from agricultural waste fibre comprising the steps of:
(a) mechanically sorting the agricultural waste fibre to form a sorted fibre having uniform length;
(b) chemically treating the sorted fibre with an alkali mixture to form alkali-treated fibre;
(c) drying the alkali-treated fibre to form a dried fibre; and
(d) softening the dried fibre by exposing the dried fibre to a softening composition to obtain the textile-grade fibre, wherein the softening composition comprises an enzyme, a polymer, a vegetable oil selected from a group of castor oil, palm oil and any blends thereof, and water.
2. The method as claimed in claim 1, wherein the step (a) of mechanically sorting the agricultural waste fibre comprises taking the agricultural waste fibre through a roller comprising a feed roller, or a spike roller, or both to form the sorted fibre.
3. The method as claimed in claim 1, wherein the step (b) of chemically treating the sorted fibre comprises treating with the alkali mixture for a time period of up to 2 hours, at a temperature in a range of 85? to 100?, and at a material to liquor ratio (MLR) of 1:5.
4. The method as claimed in claim , wherein the alkali mixture comprises an alkali and a silicone mixture, wherein the alkali is present in an amount of 5% to 8% by weight and the silicone mixture is present in an amount of 0.5% to 2% by weight.
5. The method as claimed in claim 1, wherein drying the alkali-treated fibre comprises hydroextraction in an hydroextractor followed by drying in an oven, or drying the alkali-treated fibre under sun, or a combination of both.
6. The method as claimed in claim 1, wherein softening the dried fibre comprises exposing the dried fibre to the softening composition at a softening composition to dried fibre ratio of 3:20 for a time period of up to 24 hours.
7. The method as claimed in claim 1, wherein the softening composition comprises the enzyme, the polymer, the vegetable oil and water in the ratio of 1:1:1:7 by weight.
8. The method as claimed in claim 1, wherein the enzyme comprises a pectinase, or a xylanase or any combinations thereof.
9. The method as claimed in claim 1, wherein the silicone mixture comprises a silicone polymer.
10. The method as claimed in claim 1, wherein the polymer is a copolymer of ethylene oxide (EO), or propylene oxide (PO) or a combination of EO and PO with a fatty alcohol.
11. A softening composition for softening of fibre derived from agricultural waste fibre to produce textile-grade fibre, wherein the softening composition comprises an enzyme, a polymer, a vegetable oil selected from a group of castor oil, palm oil and any blends thereof, and water.
12. The softening composition as claimed in claim 11, wherein the softening composition comprises the enzyme, the polymer, the vegetable oil and water in the ratio of 1:1:1:7 by weight.
13. The softening composition as claimed in claim 11, wherein the enzyme comprises a pectinase, or a xylanase or any combinations thereof.
14. The softening composition as claimed in claim 11, wherein the polymer is a copolymer of ethylene oxide (EO), or propylene oxide (PO) or a combination of EO and PO with a fatty alcohol.