FOR THE SAME

TECHNICAU FIEUD

[0001] The present disclosure relates to the field of yarns used in polymer net used in aquaculture and other underwater applications. In particular, it pertains to a method of manufacturing yam with core-shell with improved properties, a system and across-linking composition for the same.

BACKGROUND

[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0003] Fish proteins and fatty acids are healthy and desirable components for human nutrition. For this reason, seafood has been part of human diet from ancient times. The industrial revolution of 19 ^th century opened fast fishing areas, when commercial fishing vessels were powered first by steam and later by combustion engines. However, overfishing during the 20 ^th century depleted fish stocks. Since then, aquaculture experienced substantial advances.

[0004] With rapid development of aquaculture, arose requirement of a large amount of fishing nets that are used for making enclosures to hold the fish. These nets are usually made of a polymeric material such as PVC, polypropylene or nylon. Nets used in aquaculture are of different mesh sizes and are processed into a variety of net cages/net enclosures/fish cages. Since the nets remain in water, fresh water or seawater, for a long time, they are vulnerable to fouling due to growth of organisms like algae, hydroids, snails, measles moss, fungi, barnacles, mussels, oysters and amphipods. Fouling impedes free flow of water through the net, resulting in lack of nutrients for fish and reduction of dissolved oxygen, thereby affecting production of fish. Traditionally the problem is overcome by periodical manual cleaning of the nets, resulting in a waste of manpower, material and time.

[0005] Another problem faced with the nets in aquaculture is abrasion of the net due to friction between the nets, net to metal parts, net to ropes, and also with water. Abrasion creates defects and loss in strength, leading to breakages and resultant fish loss due to escape. Therefore, there is a requirement of nets for aquaculture that have anti-fouling and abrasion resistant properties.

[0006] Properties such as anti-fouling and abrasion resistance may be provided by coatings. However, the polymers generally employed are thermoplastic polymers having lacunas like non-polarity, little branching etc. They have chemically inert and nonporous surfaces with low surface energy causing them to be non-receptive to bonding with coatings. Further, although a number of processes of surface modification are known, where techniques are employed on the finished polyolefin products. Alternatively, additive incorporation is carried out to achieve desired properties in polymers as per applications but higher loading of additives weakens or diminishes the strength of polymer yarns.

[0007] Thus, there is a need in the art to develop a method of manufacturing yarn that effectively imparts improved properties to the yarn without compromising its strength to be used in nets for under water application like aquaculture.

OBJECTS OF THE INVENTION

[0008] A general object of the present disclosure is to provide a method of manufacturing yarn for under water application net that satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.

[0009] An object of the disclosure is to provide a method of manufacturing yarn for under water application net that effectively improves anti-fouling and abrasion resistant properties of the yarn.

[0010] Yet another object of the disclosure is to provide a method of manufacturing yarn that does not compromise strength of the yarn.

[0011] Still another object of the present disclosure is to provide a system for manufacturing yarn for net for underwater application.

SUMMARY OF THE INVENTION

[0012] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in Detailed Description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0013] In an aspect the present disclosure relates to a system for manufacturing core-shell polymer yam. [0014] In another aspect, the present disclosure provides a system (100) for manufacturing core-shell polymer yarn, wherein the system comprises of: an extrusion barrel (110) for receiving a polymer and converting said polymer into molten state for extrusion; a die (112) fitted at a distal end of the extrusion barrel (110) for extruding the molten polymer intoyam: a quenching bath (114) containing an oxidising solutionpositioned downstream of the die to receive the extruded yarn for quenching and surface modification; optionally a circulation bath (116) circuitously attached to the quenching bath for external cooling of the oxidising solution; first godet rollers(118) configured to pull the surface modified yarn from the quenching bath (116) to pass over the first godet rollers and under a godet roller wiper(120) for wiping excess oxidising solution; a treatment tank(130) connected to the wiper (120) and containing cross- linkingcomposition for treating the surface modified yarn with said cross-linkingcomposition and cross linking the surface modified yarn to form the shell on the surface of the yarn to provide a core- shell yarn; a curing tray(140) containing a catalystsolutionand configured to receive the core- shelly arn fromtreatment tankand allowing the deposition of the core- shell yarn with the catalyst solution; a hot air oven(150) configured to receive the core-shell yarn from the curing tray(140) deposited with catalyst solution and pass through the hot air oven (150) for evaporating any remainder solution on the surface of the yarn and curing the core-shell yarn; second godet rollers(160) configured to continuously pull the core-shell yarn from the hot air oven (150) and stretchthe core-shell yarn; and optionally a winder(170) connected to the second godet rollers for winding the core shell yam over said winder.

[0015] In another aspect, the present disclosure provides a system for manufacturing core shell polymer yarn like system (100) except that the system comprises a single treatment tray in place of separate treatment tank and curing tray, wherein the single treatment tray comprises both the treatment solution and catalyst solution.

[0016] In an aspect, the present disclosure relates to a method of manufacturing a core-shell yarn with improved properties.

[0017] In an aspect, the method of manufacturing core-shell yarn comprises the steps of: (a) melting a polymer by heating in an extrusion barrel(llO) to give a molten polymer;

(b) extruding the molten polymer through a die(l 12) to form yarn;

(c)quenching the yarn in a quenching bath(114) containing an oxidising solution for surface modification of the yam;

(d) optionally cooling the oxidising solution in a circulation bath (116);

(d) pulling the surface modified yarn over first godet rollers(118) and passing under a godet roller wiper(120) thereby wiping excess oxidising solution;

(e) treating the surface modified yarn with across -linking composition and a catalyst solution sequentially or simultaneously, wherein, the sequential treatment comprises treating the surface modified with a cross-linking solution contained in atreatment tank(130) allowing the cross-linking of the surface modified yarn with cross-linking composition to form a shell on the surface of the yam to provide a core- shell yam and drawing the core- shell yarn through a curingtray(140) containing a catalystsolution and allowing the deposition of the core-shell yarn with the catalyst solution, the simultaneous treatment comprises treating the surface modified with a cross- linking solution and catalyst solution contained in a treatment tank (130), allowing the cross- linking of the surface modified yam with cross-linking composition to form a shell on the surface of the yarn to provide a core-shell yarn and allowing the deposition of the core-shell yarn with the catalyst solution;

(f) curing the core-shell yam deposited with catalyst solution by passing said core shell yam in a hot air oven(150) to provide cured core-shell yarn;

(g) pulling the cured core-shell yam from the hot air oven (150) by second godet rollers(160) and stretching said core- shell yam; and

(h) optionally winding the core- shell yam over a winder(170).

[0018] The core-shell yarn obtained by the method of the present disclosure can be used for long periods without loss of the acquired properties and is suitable for use in preparing nets for under water and other applications.

[0019] In one more aspect the present disclosure provides a method for treating the polymer net to provide antifouling and abrasion resistant net, the method comprising: surface modifying the net by treating the polymer net with an oxidizing solution; treating the net with cross-linking composition and allowing the cross-linking of the modified surface of the net with cross-linking composition; treating the cross-linked net with the catalyst solution and passing through hot air oven to remove any traces of the solution present in the net and provide the cured net to provide coated net.

[0020] Other aspects of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learnt by the practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are included to provide a further understanding of the present disclosure and are

[0022] incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0023] FIG. 1 is a representative image of a system formanufacturing a core-shell yam in accordance with an exemplary embodiment of the present disclosure.

[0024] FIG. 2is a representative layout of a part of the system for manufacturing a core-shell yarn showing pulling mechanism through treatment tank and curing tray in accordance with an exemplary embodiment of the present disclosure.

[0025] FIG. 3 illustrates an exemplary flow diagram of treating the polymer net to provide coated net in accordance with an exemplary embodiment of the present disclosure.

[0026] FIGs.4 to 7 are tables showing different cross-linkingcompositionsfor cross-linking of the surface modified yarn to provide a core- shell yarn in accordance with exemplary embodiments of the present disclosure.

[0027] FIGs. 8(a)-d) arepictorial representation of various components of a prototype of the system for manufacturing yarn in accordance with an exemplary embodiment of the present disclosure, wherein FIG. 8(a)shows a quenching bath vessel (114) containing an oxidising solution positioned downstream of the die to receive the extruded yarn for quenching and surface modification with the oxidising solution; FIG. 8(b) shows surface modified yams passing from oxidizing solution ; FIG. 8(c) shows yarn passing through treatment tank containing cross linking solution; andFIG.8(d) shows yarn passing through curing tray containing catalyst solution; and FIG. 8(e. shows a circulation bath (116) containing oxidising solution.

[0028] FIGs.9 shows raw yarn and different representations of a core-shell yarn, wherein FIG. 9(a) is a pictorialimage of a raw yam; FIG. 9(b) is pictorial image of core-shell yarn in accordance with the present disclosure; FIG. 9(c) is a representative image of core-shell yarn and FIG. 9(d) shows a representative image showing a polyolefin core yam encapsulated in a shell.

DETAILED DESCRIPTION

[0029] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

[0030] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply. [0031] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” The term “about” preceding any value can mean +10 of said value. Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0032] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. [0033] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0034] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified.

[0035] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.

[0036] Various terms are used herein. To the extent a term used in a claim is not defined, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.

[0037] The terms ‘yam’ as used herein means a yarn made of polymer.

[0038] The term “polyolefin” and “polymer” as used herein are used interchangeably.

[0039] The term core-shell as used herein refers to a core of polymer yam encapsulated or surrounded by a shell resulting from cross-linking of the surface of the polymer yamwith resin comprised in a cross-linkingcomposition along with additives.

[0040] The present disclosure relates to polyolefin core-shell yams.

[0041] The present disclosure relates to providing core-shell yarn with improved properties for example having antifouling property and abrasion resistant property. The present disclosure core-shell yams can be used for preparing polymer net used in aquaculture, underwater applications and several other applications.

[0042] Embodiments described herein relate generally to system for manufacturing core- shell polymer yarn, a method for manufacturing core-shell yarn and cross-linking composition for cross-linking of surface modified yam to provide a core-shell yarn.

[0043] In an embodiment the present disclosure relates to a system for manufacturing core shell polymer yam.

[0044] Referring to FIG. 1, a system (100) for manufacturing core-shell polymer yarn in accordance with an embodiment of the present disclosure is shown, wherein the system comprises of: an extmsion barrel (110) for receiving a polymer and converting said polymer into molten state for extrusion; a die (112) fitted at a distal end of the extmsion barrel (110) for extmding the molten polymer into yarn: a quenching bath (114) containing an oxidising solution positioned downstream of the die to receive the extruded yarn for quenching and surface modification; optionally a circulation bath (116) circuitously attached to the quenching bath for external cooling of the oxidising solution; first godet rollers (118) configured to pull the surface modified yarn from the quenching bath (114) to pass over the first godet rollers(118) and under a godet roller wiper (120) for wiping excess oxidising solution; a treatment tank (130) connected to the wiper (120) and containing cross-linking composition for treating the surface modified yarn with said cross-linking composition and cross linking the surface modified yarn to form the shell on the surface of the yam to provide a core- shell yam; a curing tray (140) containing a catalyst solution and configured to receive the core shell yarn from treatment tank and allowing the deposition of the core-shell yarn with the catalyst solution; a hot air oven (150) configured to receive the core-shell yam from the curing tray (140) deposited with catalyst solution and pass through the hot air oven (150) for evaporating any remainder solution on the surface of the yarn and curing the sore-shell yarn; second godetrollerd (160) configured to continuously pull the core-shell yarn from the hot air oven (150) and stretch the core-shell yarn; and optionally a winder (170) connected to the second godet rollers for winding the core shell yam over said winder.

[0045] In an embodiment, the extruder barrel (110) is divided into various zones for ease of temperature control in each zone requiring heating at different temperatures ranging from about 150 °C to 250 °C. In an embodiment, the extruder barrel (110) comprises a hollow barrel chamber disposed horizontally with one or more screws to regulate the rate of intake of polymer for the processing.

[0046] In an embodiment, the extruder barrel (110) is distally connected to a die (112). A gear pump is fitted between the end of the extruder barrel and the die to produce a steady high pressure and consistent and higher output from the die. The die may be one or more in number.

[0047] In an embodiment, the die comprises apertures for extruding the molten polymer therefrom in the form of filaments to form yarn. Each aperture may be about 0.5 to 1.5 mm in diameter, preferably 1 mm in diameter. The number of apertures depends upon the number of yarns desired.

[0048] In an embodiment, to avoid increase in temperature of oxidizing solution due to continuous addition of hot yam in quenching bath, a circulation bath (116) can be used. The circulation bath (114) can maintain oxidizing solution temperature by circulating cooled oxidizing solution in quenching bath and cooling of hot oxidizing solution. The circulation bath made up from hollow copper tubes, filled with circulating cooled water. These cooled copper tube helps to cool the hot oxidizing solution; the cooled oxidizing solution is resent to quenching bath.

[0049] In an embodiment, the speed of the first godet rollers (118) can be set at about50 mpm to about 60 mpm (revolution meter per minute).

[0050] In an embodiment, the distance between the quenching bath (114) and fist godet rollers(l 18) may be about 50 cm to about 150 cm, preferably the distance can belOOcm. [0051] In an embodiment, the distance between the first godet rollers(118) and the treatment tank (130) may be set at about 50 cm to about 150 cm, preferably it may be set at about 100cm.

[0052] In an embodiment the treatmenttank(130) can have a defined dimension. The length may range from about 250 cm to about 350 cm. The width may vary from about 70 cm to about 150 cm. The depth may range from about 10 cm to about 15 cm. In one specific embodiment, the dimension of the treatmenttank maybe about 270cm x 90cm x 10 cm (LxWxD). The treatment tank may be placed at the height of 250 cm to about 350 cm, preferably at a height of about 300 cm.

[0053] In an embodiment the curing tray (140) can have a defined dimension. The length may range from about 250 cm to about 350 cm. The width may vary from about 70 cm to about 150 cm. The depth may range from about 10 cm to about 15 cm. In a specific embodiment, the size of the curing tray maybe about 270 cm x 90 cm x 10 cm (LxWxD). The curing tray may be placed at a height of about 250 cm to about 350 cm, preferably at a height of about 300 cm.

[0054] In an embodiment, the distance between treatment tank (130) and curing tray (140) may be about 25 cm to about 100 cm, preferably the distance can be about 50 cm.

[0055] The curing tray can be operatively coupled to a curing means selected from an infra red heater, UV curing means and hot air dryers.

[0056] In a specific embodiment, the hot air oven may be 400 cm X 100 cm (LXW) in size. [0057] In an embodiment, the hot air is circulated in the hot air oven by circulating fans to maintain uniform temperature throughout the oven.

[0058] Referring to FIG. 2, it shows, pulling mechanism through treatment tank and quenching tray in accordance with an exemplary embodiment of the present disclosure.FIG. 2 showsa treatment tank (130) that contains the cross-linking composition, tension rollers (132) and (134) that maintain tension in the yam as the yarn passes through the treatment tank(130) to a curing tray (140). A pull mechanism at the second godet rollers (160) continuously pulls the yarn (105) at the end of the curing tray such that yam is pulled from the first godet rollers (118) through the treatment tank and the curing tray at a desired speed so that the yam is in the treatment tank and the curing tray for a desired length of time.

[0059] In an embodiment, the treatment tank is sized in relation with the speed of pulling of the yarn such that the yarn remains immersed in the cross-linkingcomposition for a desired duration. Similarly, the curing tray may be sized in relation with the speed of pulling of the yarn such that the yarn remains in the curing tray for a desired duration.

[0060] In an embodiment, the present disclosure provides a method for manufacturing core shell yarn so as to provide core-shell yarn with desired properties such as anti-abrasiveness, anti-fouling, anti-radar and the like without compromising on the strength of the yam.

[0061] The present disclosure helps to overcome shortcomings of commercial processes by providing a one system pultmsion method for producing yarn which can be a monofilament yarn or joint filaments yarn, said method comprises the steps of extrusion, surface modification, and core shell yam manufacture. The polymer yarn forms the core surrounded by the shell imparting anti-abrasive, anti-fouling properties to the core-shell yam (FIGs. 9

(b)-(d)).

[0062] In an embodiment, a method of manufacturing acore-shell yarn comprises the steps of:

(a) melting a polymer by heating in an extrusion barrel (110) to give a molten polymer;

(b) extruding the molten polymer through a die (112) to form yam;

(c) quenching the yam in a quenching bath (114) containing an oxidising solution for surface modification of the yam;

(d) optionally cooling the oxidising solution in a circulation bath (116);

(d) pulling the surface modified yarn over a first godet rollers (118) and passing under a godet roller wiper (120) thereby wiping excess oxidising solution;

(e) treating the surface modified yam with a cross-linking composition and a catalyst solution sequentially or simultaneously, wherein, the sequential treatment comprises treating the surface modified with a cross-linking solution contained in a treatment tank (130) allowing the cross-linking of the surface modified yarn with cross-linking composition to form a shell on the surface of the yarn to provide a core-shell yarn and drawing the core-shell yarn through a curing tray (140) containing a catalyst solution and allowing the deposition of the core-shell yam with the catalyst solution, the simultaneous treatment comprises treating the surface modified with a cross- linking solution and catalyst solution contained in a treatment tank (130), allowing the cross- linking of the surface modified yam with cross-linking composition to form a shell on the surface of the yarn to provide a core-shell yarn and allowing the deposition of the core-shell yarn with the catalyst solution;

(f) curing the core-shell yam deposited with catalyst solution by passing said core shell yam in a hot air oven (150) to provide cured core-shell yarn;

(g) pulling the cured core-shell yarn from the hot air oven (150) by second godet rollers (160) and stretching said core-shell yarn; and

(h) optionally winding the core- shell yarn over a winder (170).

[0063] The method of the present disclosure provides in-situ preparation of the core-shell yarn. [0064] In an embodiment, the polymer may be a polyolefin, which may be a single polymer or a blend of polymers selected from polyethylene, polypropylene, high density polyethylene, poly(ethylene terephthalate) (PET), PVC, and nylon. The polymer may be present in the form of granules or pellets.

[0065] In a specific embodiment, prior to melting the polymer granules or pellets of a single polymer or a blend comprising different polymers may be mixed as per desired concentration in a mixing chamber and uniform mixing maybe performed by a blade, to obtain a homogeneous mixture of polymers. Optionally, the mixture of polymers maybe placed in an oven at a temperature rangingfrom about 80 °C to about 100 °C for about 1-3 hours in order to expel any moisture from polymer prior to extrusion. This is a precautionary step in an attempt to reduce the number of imperfections during the extrusion process caused by the presence of moisture within the barrel.

[0066] The extrusion process includes melting the polymer in an extrusion barrel and where the polymer is extruded through a die. In an exemplary embodiment, a single screw extrusion system maybe used (FIG. 1). The extrusion process starts with the addition of granules or pellets of a single polymer or a blend of polymers in a hopper into an extrusion barrel(l 10). The barrel of an extruder is a hollow chamber disposed with one or more screw(s). The screw(s)present in the barrelcontrols the polymer rate intake. For ease of control, the barrel is divided into zones or regions. A zone is a part or section of an extruder barrel. The extrusion barrel maybe divided into zones, wherein the temperature of each zone maybe different. Zone wise heating is the separate heating, and temperature control, of each zone is regulated by a separate controller. The extrusion process involves conversion of the granules or pellets of a single or blend of polymers into molten form by heating the extrusion barrel. The extrusion barrel may be electrically heated and may be heated with the help of resistance coils, bands, or cuffs that may be strapped or bolted around the barrel.

[0067] The temperature of zones within the extrusion barrel may be set in the range of about 210°C to about 265°C. First zone’s temperature maybe set at the lowest value as this helps prevent premature melting and bridging of the polymer in feed throat.

[0068] The molten polymer is extruded from the apertures of the die (112) fitted distally at the end of the extrusion barrel (110). Upon extrusion through apertures of die (112), the molten polymer isextruded in the form of a filament. The molten polymer gets converted into the yam after passing through the apertures of die (112). The temperatures of the different zones are gradually increased until the polymer reaches at the end of the die (112). The temperature of the die (112) is maintained at about 265°C for uniform release of yam from apertures.

[0069] Quenching of the yarn helps to cool down the heated yarn and restricts the crystallization process of polymer. The yarn coming out from the die is directly quenched in a quenching bath (114). The quenching bath is filled with the oxidizing solution for surface modification. The temperature of quenching bath may be maintained below 25°C, preferably in the range of about 10 °C to about 25 °C). The yarn may get quenched in the oxidizing solution and its surface modification or surface functionalization maybe carried out by addition of functional groups on the surface of yam. The functional groups introduced on the surface of yam can be selected from acidic, hydroxyl, carboxyl, or combinations thereof. This treatment also reduces the contact angle for water from surface of the yam.

[0070] In an embodiment, due to continuous addition of hot yam in quenching bath an increase in temperature of oxidizing agent may take place. To avoid such an increase, a circulation bath (116) may be used. The circulation bath (116) maybe made up of hollow copper tubes filled with cooled water. In this case the hot oxidising solution maybe withdrawn from the quenching bath (114) to the circulation bath (116). The circulation bath (116) maintains oxidising solution’s temperature by circulating cooled water through copper tubes. The cooled oxidising solution is then resent to the quenching bath (114).

[0071] In an embodiment, the surface modification is carried out with the using an oxidizing solution. The oxidising solution comprises an oxidizing agent selected from sulphuric acid, chromic acid, hydrochloric acid, potassium permanganate, sodium hypochlorite, hydrogen peroxide.

[0072] In an embodiment the oxidising solution is selected from a mixture of sulphuric acid and chromic acid: mixture of chromic acid and hydrochloric acid; mixture of sulphuric acid, chromic acid and potassium permanganate; or mixture of chromic acid, hydrochloric acid and potassium permanganate.

[0073] Exemplary compositions that may be employed as oxidising solution include: mixture of sulphuric acid and chromic acid (0.01 N to 5N); mixture of chromic acid and hydrochloric acid (0.01 N to 5N); mixture of sulphuric acid, chromic acid and potassium permanganate (0.01 N to 5N); or mixture of chromic acid, hydrochloric acid and potassium permanganate (0.01 N to 5N).

[0074] In some specific embodiments, the surface oxidation may involve a pre-treatment step, wherein the yarn is dipped in hot water having temperature from 60-90°C to remove any contaminations, including but not limited to, particulate matters, dust, and oil which may get attached to the yarn’s surface during production. The yarn is thereafter dried to remove any water, which may be done in a centrifugal rotating hot drying chamber.

[0075] In an embodiment, residence or travel time of the yam in the oxidising agent may be about a minute. Preferably, the time may be about 5-20 seconds and may vary with the concentration of the oxidation agent in the oxidizing solution.

[0076] In an embodiment, the surface modified yam may then be pulled out by the first godet rollers (118) attached to the godet roller wiper (120). The wiper wipes out the excess oxidizing solution from the yarn.

[0077] In an embodiment, after the yarn has been subjected to the surface oxidation and wiping of the excess oxidizing solution by the wiper (120), the yarn may be passed through the cross-linkingcomposition. The yarn is pulled as it is passed through the treatment tank(130) and the curing tray (140).

[0078] In a preferred embodiment, the yarn immersed in the treatment tank (130) may require a residence or travel time of about 15 seconds to about 1 minute, preferably 30 seconds to 1 minute. During this step the surfacemodified yam is treated with the components of the cross- linkingcomposition to provide a crosslinking shell on the polymer core of the yarn to give core- shell yarn.

[0079] In an embodiment, the present disclosure provides across-linking composition. In an embodiment, the cross-linkingcomposition may be based in a solvent. The solvent may be an organic solvent or water.

In an embodiment, the cross-linking composition comprises a polymeric resin, and a controlled release agent.

[0080] The polymeric resin may be a marine grade polymeric resin or a blend of resins selected from the group consisting of epoxy, polyurethane, unsaturated isophthalic polyester resin, and epoxy-based vinyl ester resin.

[0081] In an embodiment, the polymeric resin may be unsaturated isophthalic polyester resin. [0082] In another embodiment, the polymeric resin may be mixture of unsaturated isophthalic polyester resin and epoxy resin, wherein the unsaturated isophthalic polyester resin may constitute 50% -90% by weight.

[0083] In yet another embodiment, the polymeric resin may be mixture of unsaturated isophthalic polyester resin and polyurethane, wherein the unsaturated isophthalic polyester resin may constitute 50% -90% by weight.

[0084] In another embodiment, the polymeric resin may be mixture of polyurethane and epoxy resin, wherein the polyurethane may constitute 50% -90% by weight. [0085] In an embodiment, the ratio of polyurethane to epoxy resin maybe selected from an amount by weight % from 90:10, 80:20, 70:30, 60:40 or 50:50.

[0086] In an embodiment, the mixture of polyurethane and epoxy resin forms a shell around polymer core.

[0087] In an embodiment, use of the epoxy, polyurethane, isophthalic polyester resin, or epoxy-based vinyl ester resin forms ultra-high cross linking with the surface modified or the surface functionalizedyarn, as well as renders auto shape forming properties.

[0088] In an embodiment, the controlled releasing agents is selected from but not limiting to polyethylene glycol (PEG), polyethylene oxide (PEO), polyoxyethylene (POE) poly vinyl pyrrolidone (PVP) or combination thereof.

[0089] In an embodiment, the cross-linking composition further or optionally comprises an anti-fouling material and an anti-abrasive material.

[0090] In an embodiment, the anti-abrasive material may be chopped fibres of any of bamboo, banana, jute and wool, such as deccani wool. The anti-abrasive material may constitute 2-10%, preferably 5% by weight of the cross-linking composition.

[0091] In an embodiment, the anti-fouling material may be any or a combination of copper metal particles, copper pyrithion, coper iodide, cuprous oxide, zinc oxide, or econea (Tralopyril). In an embodiment, the anti-fouling material may be present in an amount ranging from 1% to 40% by weight of the cross-linkingcomposition.

[0092] In an embodiment, the anti-fouling material may be any or a combination of micronized copper powder, cuprous oxide, copper pyrithion, or tralopyril.

[0093] In an embodiment, the micronized copper powder may be present in an amount ranging from about 10% to about 35% by weight of the cross-linkingcomposition. The cuprous oxide may be present in an amount ranging from about 10% to about 35% by weight of the cross-linkingcomposition. The copper pyrithion may be present in an amount of about 1% to about 5% by weight of the cross-linkingcomposition. The Tralopyril may be present in an amount of about 1% to about 5% by weight of the cross-linkingcomposition.

[0094] In another embodiment, the cross-linkingcomposition may also include a plasticizer if required for the polymeric resin being used. The plasticizer may be an esterified vegetable oil. The plasticiser may be present in an amount in the range of about 1% to about 15% by weight of the cross-linkingcomposition.

[0095] In an embodiment, the cross-linkingcomposition may further comprise a solvent. The solvent may be selected from styrene, methanol, or xylene. [0096] In an embodiment, the cross-linkingcompositionmay further comprise additives. The additives may be selected from the group comprising of EMI shielding factors, thermal conductors, electrical conductors, anti-radars, super absorbent polymers, gelling agents, super absorbents, slippery agents, hygroscopic agents, super hydrophobic components, high density organic materials, photochromic inorganic materials, smog absorbing materials, sinking materials, antibacterials, antimicrobials, antivirals, flame retardants, and combinations thereof.

[0097] In an embodiment, the additives may be graphene, copper nano/micro alumina, nano silver, PVP, PEG, T1O2, graphite, barium sulphate, calcium carbonate, lead, copper, oxides of transition metals, silver-based compound, organic compound spiropyran family, hybrid materials polyoxometalates, mixture of resin and zeolite - Na20, S1O2, AI2O2; nano-silver, anti-viral drugs, anti-bacterial drugs, antifungal drugs, aluminium hydroxide, magnesium hydroxide, metal hydroxides or combinations thereof. The transition metals for example can be tungsten, molybdenum, titanium, vanadium. The silver-based compounds can be halides. [0098] The high density inorganic materials like barium sulphate, T1O2, calcium carbonate, lead, or copper improve the specific density of thecomposition enabling it to sink in water. [0099] In an embodiment, the additives may be present in an amount in the range of about 0.5% to about 50% by weight of the cross-linkingcomposition.

[00100] In an embodiment, the yam obtained after treatment in the treatment tank (130) is drawn into the curing tray (140). The curing tray comprises a catalyst solution. The treatment at the curing tray create conditions for polymerizing, curing and evaporation of solvents off the yam. In particular, the yam is heated to 60-80°C for the curing to occur and speed of the yarn is controlled so that it spends about 5 to 15 minutes, preferably 10 minutes in the curing tray.

[00101] In an embodiment, the catalystsolution may comprise a curing and catalyst agent selected from cobalt octate, methylethyl ketone, or combination thereof. Cobalt octate may function as a curing agent. Cobalt octate can be present in an amount ranging from 1% to 10% by weight. Methylethyl ketone may function as a catalyst. Methylethyl ketone can be present in an amount ranging from about 1% to about 10% by weight.

[00102] After deposition of the catalystsolution on the yarn it may be passed in hot air oven (150). The hot air circulated in the oven is circulated by fans to maintain uniform temperature throughout the oven. Any excess solvent present gets evaporated due to elevated oven temperature and the curing mechanism is completed in the oven. The travel time from oven may be about 15 seconds. The temperature may be maintained at about 80 °C to about 100 °C.

[00103] After passing the core- shell yarn from the hot air oven, yarns may be travelled towards the secondgodet rollers (160) for stretching. The stretching itself starts from the first godetrollers (118) because second godet rollers(160) continuously pulls and stretches the core-shell yam. The stretch ratio between the first godet rollers (118) and second godet rollers (160) may be appropriately set on the basis of MPM. In an embodiment, the speed of the second godet rollers can be set at 65-75MPM revolution meter per minute.

[00104] The tenacity and % elongation of the core-shell yarn depends upon the stretch ratio. After stretching of yarn by second godetrollers (160), the core-shell yarns can be wound on winder cops (170 - not shown). Thecore-shell obtained is wound on a winder which is associated with aluminium, plastics or paper cops, cones or cylinders.

[00105] In an embodiment, the yam can be pre-treated, oxidised and treated as described above, whereupon, the treated yam can be knitted to form an aquaculturehybrid net.

[00106] In an embodiment, the present disclosure provides core-shell yam prepared by the method as described above with the core-shell stmcture.The core-shell yam overcomes problems of strength reduction due to addition of higher concentration of additive in yarn for desired property.

[00107] In an embodiment, the core-shell yarn is formed into net.

[00108] In an embodiment, the net for underwater applications that has improved anti fouling and abrasion resistant properties is provided. The nets have a long life. The nets exhibit cross linking and auto shape forming properties thereby increasing the life of the coating. The nets usechopped natural fibres. The net allows use of one or more polymeric materials in different combinations.

[00109] In an embodiment, the present disclosure provides an aquaculture net having anti fouling and high abrasion resistant properties that obviates problem faced in aquaculture with conventional nets. In an embodiment, the present disclosure provides a material for coating on the nets such that the coated net acquires anti-fouling and high abrasion resistant properties. The disclosed material possesses auto shape forming property, and therefore the material coated on surface of the net does not get damaged as a result of deformations that the aquaculture nets are subjected to during use. The core-shell yarn obtained by the method of the present disclosure can be used for long periods without loss of the acquired properties and suitable for use in preparing nets for under water and other applications. [00110] In one more aspect the present disclosure provides a method for treating the polymer net to provide antifouling and abrasion resistant net, the method comprising: surface modifying the net by treating the polymer net with an oxidizing solution; treating the net with cross-linking composition and allowing the cross-linking of the modified surface of the net with cross-linking composition; treating the cross-linked net with the catalyst solution and passing through hot air oven to remove any traces of the solution present in the net and provide the cured net to provide coated net.

[00111] FIG. 3 illustrates an exemplary method flow diagram for a specific embodiment of the proposed method of manufacturing an aquaculture yam, in accordance with one of the embodiments of the present disclosure. The disclosed method 200 includes step 202 of oxidizing surface of polymer net such as HDPE, to generate functionalities on the surface of the polymeric net, which helps to create cross linking of the cross-linkingcomposition with the surface of the net. Detailed process followed including pre-treatment has been enumerated in earlier paragraphs.

[00112] After surface oxidation, the method 200, at step 204, involves an optional post treatment of oxidized net. The post treatment is done by engrossing the net in water to remove the excess acid present on the net surface after oxidation. At step 206, the net may be dried in centrifugal rotating hot drying chamber to remove any water from the post treatment. [00113] After the net has been subjected to the surface oxidation, the process of coating the surface of the net with the cross-linkingcompositionby the pultmsion process using the system 100 can be taken up. At step 208 of the method, the dried net may be passed through a treatment tank, such astreatment tank (130) shown in figure 2, filled with thecross-linking compositionto allow wetting of the net for 30-60 sec. In an embodiment, the speed of pulling of the net is maintained such that the net remains dipped for 30-60 sec.

[00114] While the net is being passed through the treatment tank tension in the net may be maintained, as shown at step 210, using tension rollers, such as tension rollers (132, 134) shown in FIG. 2. Maintaining the tension ensures that all parts of the surface of the net are exposed and are evenly coated.

[00115] After wetting or coating of surface of the net in the treatment tank, the net may be subjected to curing, as shown at step 212 in Figure 3. Curing may be done in a curing tray( 140) shown in Figure 2. The curing tray may be provided with any or a combination of curing agents, catalyst agents IR heaters, UV lamps and/or hot air dryers. [00116] As all the solvents may not evaporate during the curing, the method, at step 214, involves heating the net at 80°C for 30 minutes for removal of remaining traces of solvents from the net.

[00117] Aquaculture net and ropes are subjected to coating using cross- linkingcompositions as shown in tables ofFigures4 to 7for evaluating the performance of the aquaculture net in respect of anti-fouling and abrasion resistance properties.

[00118] It was found that a net treated with the disclosed ultra-high cross linking hybrid composition had weight pickup of 96 % on the net. The net turns into hybrid netting after the treatment. The aquaculture net was characterized and evaluated on different parameters and it was found that the ultra-high crosslinking hybrid composition was uniformly impregnated and auto shaped as per net surface and highly cross linked with net. The mesh breaking strength was evaluated and it was found that increase in strength is up to 5% due to treatment of the cross-linkingcomposition on the net.

[00119] The wet abrasion resistant (up to break) of net improved from 100% to 112% as compared to raw net. The improvement in abrasion resistance is due to addition of chopped natural fibres, like bamboo, banana, jute and wool, in ultra-high cross linking hybrid composition. In-situ cleaning study test had been conducted on hybrid net and it was found that the material for coatingwas able to withstand 300 bar pressure on the net surface for up to 10 min under static position of cleaning.

[00120] The antifouling property of ultra-high cross-linking hybrid composition treated net was analysed after long term test period effectiveness for controlling the marine growth up to three seasons (36 months), whereas an untreated net was found to foul, necessitating removal and cleaning/or replacing of net.

[00121] Thus, the disclosed coating composition and the method for treating the nets provide a solution to the problem of fouling and abrasion of the aquaculture nets faced by the aquaculture industry.

Following are exemplary cross-linking compositions: [00122] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION

[00123] The present disclosure provides a method of manufacturing core-shell yam that satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.

[00124] The present disclosure provides a method of manufacturing core-shell yam that effectively improves the properties of the yam without wasting manpower or time.

[00125] The present disclosure provides a method of manufacturing core-shell yam that does not compromise strength of the yarn by excess addition of additives in yarn.