DESC:TECHNICAL FIELD
[0001] The present disclosure relates to a technique for surface modification of a polyolefin material for coating application of aquaculture and fishing nets. The present disclosure further relates to the field of yarns used in polymer nets used in aquaculture and other underwater applications. In particular, the present disclosure pertains to a method of manufacturing surface functionalized yarn, for various applications in aquaculture.

BACKGROUND OF THE INVENTION
[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] It is well known that many polyolefin materials, are difficult to bond due to absence of specific surface chemical functional groups capable of providing reactive sites for the establishment of strong interfacial interactions, such as acid-base interactions and/or the formation of chemical bonding (e.g. covalent, ionic, etc.) between untreated substrate and the adhesive, paint, matrix material or other adhering substance.
[0004] Various types of surface treatments are also known for increasing the bonding properties of polymers. Typical surface treatments to enhance adhesion include: mechanical abrasion; corona discharge, flame treatment, plasma treatment, UV radiation, chemical oxidation using oxidizing agents, and introduction of functional groups by surface chemical grafting.
[0005] Japanese Patent document number JPS58132029 discloses a method of treating surface of polymers based on gas discharge and chemical treatments. The gas discharge treatment includes a corona discharge treatment and/ or plasma discharge treatment. The chemical treatment includes an acid treatment, alkali treatment, and coupling agent treatment, and especially, a treatment is preferred in which a substrate is immersed in an alkaline solution containing alkali metal or alkaline earth metal ions. Disclosed combination of treatments may be effective for increasing the adhesive properties of polymeric substrates, however the disclosed treatments require at least two chemical processes which are costly and substantially increases the cost associated with industrial application.
[0006] Japanese Patent document number JP6480099 discloses a method for increasing the ability of polyimides to bond to adhesives by treating the surface of the polyimide with corona discharge, and then treating the surface with a silane based coupling agent.
[0007] The industrial revolution of 19th century opened fast fishing areas, when commercial fishing vessels were powered first by steam and later by combustion engines. However, overfishing during the 20th century depleted fish stocks. Since then, aquaculture experienced substantial advances. 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 Nylon, polyethylene, polypropylene, polyester etc.
[0008] The polyolefin like polyethylene, polypropylene has non active surface means non polar in nature i.e there is no functionality on the surface. This non functionality affects the surface bonding properties with coating or treatment of resins, rubber, paints etc. 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, abrasion due to water, sea debris, stones, ships, barge etc.
[0009] It has now been found, surprisingly, that the ability of polyolefin materials to be durably bonded to thermoplastic or thermoset polymers and/or inorganic or metallic binders in the form of adhesives, paints, coatings, matrix materials or other sub-stances may be improved by the use of very low concentrations, and/or otherwise ineffective concentrations of organ functional coupling agents and/or chelating agents by suitable co-treatment steps.
[0010] The present disclosure provides a simple, cost effective and efficient method for modifying the surface of a polyolefin material and manufacturing surface functionized yarn.
[0011] 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.
[0012] 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.
[0013] 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 thus fulfilling the written description of all groups used in the appended claims.

OBJECTS OF THE INVENTION
[0014] 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.
[0015] An object of the disclosure is to provide a method of manufacturing yarn for under water application net that effectively improves surface functionalized yarn by the treatment of oxidative chemical treatment.
[0016] Yet another object of disclosure is to provide process for online surface treatment of yarn during extrusion and offline treatment of yarn based netting.
[0017] Yet another object of the disclosure is to provide a method of manufacturing yarn that does not compromise strength of the yarn.
[0018] Still another object of the present disclosure is to provide a system for manufacturing yarn for net for underwater application.
[0019] A general object of the present disclosure is to provide an efficient technique for surface modification of a polyolefin material.
[0020] An object of the present disclosure is to provide an improved for surface modification of a polyolefin material by anchoring functional group on the surface of polyolefin material.
[0021] Another object of the present disclosure is to provide a method for converting the nature of polyolefin’s from non-polar to polar.
[0022] Another object of the present disclosure is to provide a technique to develop strong interfacial interaction between oxidized/modified polyolefin’s surfaces with coating materials.
[0023] Another object of the present disclosure is to provide a simple and cost effective method for surface modification of polyolefin material for coating application of aquaculture and fishing nets.

SUMMARY
[0024] The present disclosure relates to a system for manufacturing a surface functional polymer yarn, said system comprising:
an extrusion barrel for receiving a polymer and converting said polymer into molten state for extrusion;
a die fitted at a distal end of the extrusion barrel for extruding the molten polymer into yarn; and
a quenching bath containing an oxidising solution positioned downstream of the die to receive the extruded yarn for quenching and surface modification.
[0025] The proposed system optionally comprises a circulation bath circuitously attached to the quenching bath for external cooling of the oxidising solution. The proposed system can further include:
first godet rollers configured to pull the surface modified yarn from the quenching bath to pass over the first godet roller and under a godet roller wiper for wiping excess oxidising solution; and
optionally, a hot air oven for evaporating any remainder solution on the surface of the yarn and drying the surface functional yarn;
second godet rollers configured to continuously pull the surface functional yarn from the hot air oven and stretch the surface functional yarn; and
optionally a winder connected to the second godet rollers for winding the surface functional yarn over said winder.
[0026] The present disclosure relates to a method of manufacturing a surface functional polymer yarn comprises the steps of:
obtaining yarn by extruding molten polymer through a die;
quenching the obtained yarn in a quenching bath containing an oxidizing solution for surface modification of the yarn.
[0027] The proposed method further comprises the step of melting a polymer by heating in an extrusion barrel to yield the molten polymer. The method can further comprise the steps of:
optionally cooling the oxidizing solution in a circulation bath;
pulling the surface modified yarn over a first godet rollers and passing under a godet roller wiper thereby wiping excess oxidising solution;
optionally drying the surface functional yarn by passing said surface functional yarn in a hot air oven to provide cured surface functional;
pulling the dried surface functional yarn from the hot air oven by second godet rollers and stretching said surface functional; and
optionally winding the core-shell yarn over a winder.
[0028] The present disclosure further relates to a surface functional polymer yarn, wherein the surface functional polymer yarn is extruded from molten polymer through a die and quenched in a quenching bath containing an oxidizing solution for surface modification of the yarn.
[0029] In an aspect the present disclosure relates to a system for manufacturing surface modified yarn/surface fictionalized yarn. In another aspect, the present disclosure provides a system for manufacturing core-shell polymer yarn, wherein the system comprises of:
an extrusion barrel for receiving a polymer and converting the polymer into molten state for extrusion;
a die fitted at a distal end of the extrusion barrel for extruding the molten polymer into yarn;
a quenching bath containing an oxidizing solution positioned downstream of the die to receive the extruded yarn for quenching and surface modification;
optionally a circulation bath circuitously attached to the quenching bath for external cooling of the oxidising solution;
first godet rollers configured to pull the surface modified yarn from the quenching bath to pass over the first godet rollers and under a godet roller wiper for wiping excess oxidising solution;
the surface modified yarn pass through the a hot air oven and stretching done of surface functionalized yarn ;
and optionally a winder connected to the second godet rollers for winding the surface functionalized yarn over said winder.
[0030] In another aspect, the present disclosure provides a system for manufacturing surface functionalized yarn based net except that the system comprises a single treatment tray filled with oxidizing/surface modifier agents. The net pass/impregnate through the oxidizing/surface modifier agents filled tank and dry it with blowing the hot air.
[0031] In an aspect, the method of manufacturing surface functionalized yarn comprises the steps of:
melting a polymer by heating in an extrusion barrel to give a molten polymer;
extruding the molten polymer through a die to form yarn;
quenching the yarn in a quenching bath containing an oxidizing solution for surface modification of the yarn;
optionally cooling the oxidising solution in a circulation bath;
pulling the surface modified yarn over first godet rollers and passing under a godet roller wiper thereby wiping excess oxidising solution;
starching and drying perform in hot air oven
optionally winding the surface functional yarn over a winder.
[0032] The surface functional 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.
[0033] In one more aspect the present disclosure provides a method for treating the polymer net to provide antifouling paint bonding for antifouling property and abrasion resistant net, the method comprising:
surface modifying the net by treating the polymer net with an oxidizing solution;
treating the net with other aspects of the invention as 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.
[0034] Aspects of the present disclosure relate to an improved technique for treating surface of polyolefin materials to modify surface chemistry thereof. For example, it is desirable to treat the surface of polyolefin fibers, yarn, net, ropes and granules to improve their ability for bonding to other materials including, but not limited to, adhesives, sealants, paints, and any other reactive and/or non-reactive organic, inorganic or metallic materials, or mixtures thereof. By the term “polyolefin', as used herein, we mean PE & PP (homo polymers), co-polymers and/or their blends with other polymers.
[0035] In a preferred embodiment, it is desirable to establish a strong and durable adhesive bond between a polyolefin substrate or a polymer matrix and another polymeric and/or non- polymeric material, such as a thermoset, or thermoplastic resin, paint or coating. In order for the adhesive bond and/or composite material to perform satisfactorily, there must be good adhesion between the substrate (e.g. flat sheet, or fibre, complex shaped article, or powder) and the adhesive, paint, coating, thermoplastic, thermoset resin or non-polymeric material.
[0036] In an aspect, the present disclosure provides a method of modifying the surface of a polyolefin material including: oxidizing at least a part of the surface of the polyolefin material, such as, fibers, yarn, nets, ropes and granules material; and subsequently treating the oxidized surface with coupling agent and/or wetting agent. For example, suitable coupling agent can be organo-Zirconate, organo-titanate, organo-tin or organo-aluminate. These coupling agents may be applied from solution, vapour or any type of mechanical dispersion of a pure coupling agent or their solution and/or mixtures in any suitable solvent. If used as a solution the coupling agent may be applied as a water-based solution or in non-aqueous solution with a solvent such as an organic solvent or a mixture of both.
[0037] The coupling agent or wetting agent may be applied for any suitable concentration, for example from 0.1 % to 5% w/w. preferably, the wetting agent can be applied in the range of 0.1 to 5%
[0038] In another aspect, the disclosed method may be used in respect of polyolefin material. For example, it may be used in respect of a polyolefin, such as low density polyethylene (LDPE), polypropylene (PP), high density polyethylene (HDPE), ultra high molecular weight polyethylene (UMVVWPE), or blends of polyolefin with other polymers.
[0039] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0040] The accompanying drawings are included to provide a further understanding of the present disclosure, and are 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.
[0041] FIG.1 is a representative image of a system for manufacturing a surface functionalized yarn in accordance with an exemplary embodiment of the present disclosure.
[0042] FIG. 2 is a representative image of a system for offline preparation of a yarn based netting surface functionalized in accordance with an exemplary embodiment of the present disclosure.
[0043] FIGs. 3(a) shows a quenching bath vessel containing an oxidising solution positioned downstream of the die to receive the extruded yarn for quenching and surface modification with the oxidizing solution;
[0044] FIG. 3(b) shows surface modified yarns passing from oxidizing solution.
[0045] FIG. 4(a) shows a surface morphology of untreated and treated yarn by scanning electron microscope.
[0046] FIG. 4(b) shows a Fourier transform infrared spectroscopy of untreated and treated yarn.
[0047] FIG. 5 illustrates an exemplary flow diagram of the proposed method for surface modification of polyolefin material, in accordance with an embodiment of the present disclosure.
[0048] FIG. 6 illustrates an exemplary working for surface modification of polyolefin material for coating application for aquaculture and fishing nets, in accordance with embodiments of the present disclosure.
[0049] FIG. 7 illustrates a graphical representation of Fourier-transform infrared spectroscopy (FTIR) spectrum of high-density polyethylene (HDPE) yarn, in accordance with an embodiment of the present disclosure.
[0050] FIG. 8 illustrates a graphical representation of a FTIR spectrum of surface of modified high-density polyethylene (HDPE) yarn, in accordance with an embodiment of the present disclosure.
[0051] FIG. 9 illustrates a graphical representation of a FTIR spectrum of comparative analysis of non-modified surface and modified surface of HDPE yarn, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0052] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such details 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.
[0053] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0054] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those of ordinary skill in the art. Moreover, all statements herein reciting embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure).
[0055] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, 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.
[0056] Referring to FIGs. 1 and 2, a system for manufacturing core-shell polymer yarn in accordance with an embodiment of the present disclosure is shown at 100, wherein the system 100 comprises:
an extrusion barrel for receiving a polymer and converting said polymer into molten state for extrusion (step 1);
a die fitted at a distal end of the extrusion barrel for extruding the molten polymer into yarn:
a quenching bath containing an oxidizing solution positioned downstream of the die to receive the extruded yarn for quenching and surface modification (step 2);
optionally a circulation bath circuitously attached to the quenching bath for external cooling of the oxidising solution (step 3);
first godet rollers configured to, at step 4, pull the surface modified yarn from the quenching bath to pass over the first godet rollers and under a godet roller wiper for wiping excess oxidising solution;
a hot air oven configured to, at step 5, receive the surface modified yarn from the quenching bath and yarn pass through the hot air oven for evaporating any remainder solution on the surface of the yarn and warm the yarn;
a second godet roller configured to, at step 6, continuously pull the surface modified yarn from the hot air oven and stretch the surface modified yarn; and
optionally a winder connected to the second godet rollers for winding the surface modified yarn over said winder (step 7).
[0057] In an embodiment, the extruder barrel is divided into various zones for ease of temperature control in each zone requiring heating at different temperatures ranging from about 150 ºC to 250 ºC. In an embodiment, the extruder barrel comprises a hollow barrel chamber disposed horizontally with one or more screws to regulate the rate of intake of polymer for the processing.
[0058] In an exemplary embodiment, the extruder barrel can be distally connected to a die. A gear pump can be 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.
[0059] 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.
[0060] In an embodiment, in order to avoid increase in temperature of oxidizing solution due to continuous addition of hot yarn in quenching bath, a circulation bath can be used. The circulation bath 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. This cooled copper tube helps to cool the hot oxidizing solution; the cooled oxidizing solution is resent to quenching bath.
[0061] In an embodiment, the speed of the first godet rollers can be set at about 50 mpm to about 60 mpm (revolution meter per minute). In an exemplary embodiment, distance between the quenching bath and first godet rollers may be about 50 cm to about 150 cm, preferably the distance can be 100 cm.
[0062] 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.
[0063] 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 ranging from about 80 ºC to about 100 ºC for about 1-3 hours in order to expel any moisture from polymer prior to extrusion. This can be an exemplary precautionary step in an attempt to reduce the number of imperfections during the extrusion process caused by the presence of moisture within the barrel.
[0064] The extrusion process can include melting the polymer in an extrusion barrel, wherein the polymer can be extruded through a die. In an exemplary embodiment, a single screw extrusion system may be used. The extrusion process can start with the addition of granules or pellets of a single polymer or a blend of polymers in a hopper into an extrusion barrel. The barrel of an extruder can be a hollow chamber disposed with one or more screw(s). The screw(s) present in the barrel controls the polymer rate intake. For ease of control, the barrel can be divided into zones or regions. A zone can be defined as 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 can include separate heating and temperature control of each zone which can be regulated by a separate controller. The extrusion process can involve 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.
[0065] The temperature of zones within the extrusion barrel may be set in the range of about 210ºC to about 265ºC. First zone’s temperature maybe set at the lowest value as this helps prevent premature melting and bridging of the polymer in feed throat.
[0066] The molten polymer can be extruded from the apertures of the die fitted distally at the end of the extrusion barrel. Upon extrusion through apertures of die, the molten polymer is extruded in the form of a filament. The molten polymer gets converted into the yarn after passing through the apertures of die.
[0067] The temperatures of the different zones can be gradually increased until the polymer reaches at the end of the die. Temperature of the die can be maintained at about 265ºC for uniform release of yarn from apertures.
[0068] Quenching of the yarn can help to cool down the heated yarn and restrict the crystallization process of polymer. The yarn coming out from the die can be directly quenched in a quenching bath. The quenching bath can be filled with the oxidizing solution for surface modification. The temperature of quenching bath may be maintained below 25ºC, preferably in the range of about º5 C to about 25ºC).
[0069] The yarn may get quenched in the oxidizing solution and its surface modification or surface functionalization may be carried out by addition of functional groups on the surface of yarn. The functional groups introduced on the surface of yarn can be selected from acidic, hydroxyl, carboxyl, or combinations thereof. This treatment also reduces the contact angle for water from surface of the yarn.
[0070] In an embodiment, due to continuous addition of hot yarn in quenching bath an increase in temperature of oxidizing agent may take place. To avoid such an increase, a circulation bath may be used. The circulation bath maybe made up of hollow copper tubes filled with cooled water. In this case the hot oxidising solution may be withdrawn from the quenching bath to the circulation bath. The circulation bath maintains oxidising solution’s temperature by circulating cooled water through copper tubes. The cooled oxidizing solution is then resent to the quenching bath.
[0071] In an embodiment, surface modification can be 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 can be 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 oxidizing 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 can bedipped in hot water having temperature from 60- 90ºC 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, 5 which may be done in a centrifugal rotating hot drying chamber.
[0075] In an embodiment, residence or travel time of the yarn in the oxidizing 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 yarn may then be pulled out by the first godet rollers attached to the godet roller wiper. The wiper wipes out the excess oxidizing solution from the yarn. In an embodiment, after the yarn has been subjected to the surface oxidation and wiping of the excess oxidizing solution by the wiper, the yarn may be passed through the first slow godet and travel towards hot air blower. The travel time from oven may be about 1min. The temperature may be maintained at about 80 ºC to about 100 ºC.
[0077] After passing the core-shell yarn from the hot air oven, yarns may be travelled towards the second godet rollers for stretching. The stretching itself starts from the first godet rollers because second godet rollers continuously pulls and stretches the surface modified yarn. The stretch ratio between the first godet rollers and second godet rollers 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.
[0078] The surface modified yarn to be use for preparation of netting and ropes applicable for the underwater aquaculture use
[0079] With reference to FIG. 2, aspects the present disclosure can provide a method for treating the polymer net to provide offline surface functionalization of polyolefin’s, the whole raw net should pass through an oxidizing solution; treating the net with 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. The impregnation tank may be 20X1X1feet (LXHXW); the tank may contain two supportive rollers for net support while passing through tank. The oxidizing solution filled in tank.
[0080] In an embodiment, the surface modification can be carried out with the using an oxidizing solution. The oxidising solution can include an oxidizing agent selected from sulphuric acid, chromic acid, hydrochloric acid, potassium permanganate, sodium hypochlorite, hydrogen peroxide.
[0081] 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.
[0082] Exemplary compositions that may be employed as oxidizing 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).
[0083] In an embodiment, residence or travel time of the raw net in the oxidizing 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.
[0084] In an embodiment, the surface modified net may then be pulled out by the rollers attached. In an embodiment, after the net has been subjected to the surface oxidation, the net may be passed through the hot air blowing oven. The travel time from oven may be about 15 seconds. The temperature may be maintained at about 80 ºC to about 100 ºC.
[0085] FIG. 3a shows a quenching bath vessel containing an oxidising solution filled in tank to receive the raw net surface modification with the oxidizing solution. The oxidising solution comprises an oxidizing agent selected from sulphuric acid, chromic acid, hydrochloric acid, potassium permanganate, sodium hypochlorite, hydrogen peroxide.
[0086] In an embodiment, the oxidising solution can be 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.
[0087] Exemplary compositions that may be employed as oxidizing 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).
[0088] In an embodiment, residence or travel time of the yarn in the oxidizing 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.
[0089] FIG. 3b shows surface modified yarns passing from oxidizing solution, contain 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.
[0090] FIG. 4a depicts surface morphology of yarn by scanning electron microscope; the untreated yarn surface very smooth surface without any twist/curl. However in case of treated yarn surface found to be itched/rough/irregular/curl. The surface morphology of treated yarn clearly visualizes that, this may happen just because of treatment with oxidizing agent. The rough surface of yarn was developed due to oxidizing agent’s treatment provides the binding sites for various coating like resin, paint etc.
[0091] FIG. 4b shows an exemplary image i.e. FTIR spectra of treated and untreated yarn provide confirmation of oxidation of yarn success. The ideal HDPE possesses the function groups and which are characteristic for HDPE (polyolefin) like 2915 cm-1, 2845 cm-1 , 1472 cm-1, 1462 cm-1, 730 cm-1 and 717 cm-1 represents C-H stretch ,CH2 bend, , CH2 cm-1 rock , CH2 rock respectively. The surface functionalized yarn shows the additional peaks was observed like –OH, -COOH, C-O-O in 3600-3200cm-1, 1730-1700cm-1 and 1200-1000cm-1 respectively. The additional peaks provide confirmation that the oxidizing agents created the surface functionality of the yarn.
[0092] Embodiments explained herein relate to an improved, simple and efficient technique for surface modification of polyolefin material.
[0093] In an aspect, the present disclosure provides a method for modifying the surface of a polyolefin material including: oxidizing at least a part of the surface of the polyolefin material, such as, but not limited to, fibers, yarn, nets, ropes and granules material; and subsequently treating the oxidized surface with coupling agent and/or wetting agent.
[0094] In an embodiment, oxidizing agents, such as strong acids, for example sulphuric acid, chromic acid, hydrochloric acid etc, and mixture of potassium permanganate and sodium hypochlorite, hydrogen peroxide, mixture of sulphuric acid and potassium permanganate etc. can be used with different concentration for oxidizing the surface of the polyolefin material.
[0095] In a preferred embodiment, the chromic acid treatment can be preferred for oxidizing the surface of the polyolefin material.
[0096] In an embodiment, prior to the oxidation of surface of the polyolefin material, the polyolefin material may be treated with hot water of temperature range of 60 to 90 ºC, and after oxidation treatment a cold water wash may be given to the polyolefin material.
[0097] In an embodiment, the suitable coupling agent can be organo-Zirconate, organo-titanate, organo-tin or organo-aluminate.
[0098] In an embodiment, the coupling agents may be applied from solution, vapour or any type of mechanical dispersion of a pure coupling agent or their solution and/or mixtures in any suitable solvent. If used as a solution the coupling agent may be applied as a water-based solution or in non-aqueous solution with a solvent such as an organic solvent or a mixture of both. The coupling agent or wetting agent may be applied for any suitable concentration, for example from 0.1 % to 5% w/w. preferably, the wetting agent can be applied in the range of 0.1 to 5%
[0099] In another aspect, the disclosed method may be used in respect of polyolefin material. For example, it may be used in respect of a polyolefin, such as low density polyethylene (LDPE), polypropylene (PP), high density polyethylene (HDPE), ultra high molecular weight polyethylene (UMVVWPE), or blends of polyolefin with other polymers.
[00100] FIG. 5 illustrates an exemplary flow diagram of the proposed method for surface modification of a polyolefin material, in accordance with embodiments of the present disclosure. The proposed method 500 can include at step 502, oxidizing at least a part of surface of a polyolefin material, and at step 504, treating the oxidized surface with any or a combination of coupling agent and wetting agent.
[00101] In an embodiment, the polyolefin material can be fibers, yarn, nets, ropes, granules material and the like. The surface of the polyolefin material is oxidized by chemical oxidation.
[00102] In an embodiment, at the step 504, the oxidized surface of the polyolefin material may be treated with a different concentration of an aqueous or non-aqueous solution of the coupling agent and/or wetting agent.
[00103] In an embodiment, the surface modifying agents may be kept in hot chamber.
[00104] In an embodiment, oxidizing agents, such as strong acids, for example sulphuric acid, chromic acid, hydrochloric acid etc, and mixture of potassium permanganate and sodium hypochlorite, hydrogen peroxide, mixture of sulphuric acid and potassium permanganate etc. can be used with different concentration for oxidizing the surface of the polyolefin material.
[00105] In a preferred embodiment, the chromic acid treatment can be preferred for oxidizing the surface of the polyolefin material.
[00106] In an embodiment, prior to the oxidation of surface of the polyolefin material, the polyolefin material may be treated with hot water of temperature range of 60 to 90 ºC, and after oxidation treatment a cold water wash may be given to the polyolefin material.
[00107] In an embodiment, any suitable coupling agent or wetting agent may be used. For example, the suitable coupling agent can be organo-Zirconate, organo-titanate, organo-tin or organo-aluminate.
[00108] In an embodiment, the coupling agents may be applied from solution, vapour or any type of mechanical dispersion of a pure coupling agent or their solution and/or mixtures in any suitable solvent. If used as a solution the coupling agent may be applied as a water-based solution or in non-aqueous solution with a solvent such as an organic solvent or a mixture of both.
[00109] In an embodiment, the coupling agent or wetting agent may be applied for any suitable concentration, for example from 0.1 % to 5% w/w. preferably, the wetting agent can be applied in the range of 0.1 to 5%
[00110] FIG. 6 illustrates an exemplary working for surface modification of polyolefin material for coating application for aquaculture and fishing nets, in accordance with embodiments of the present disclosure. In an embodiment, the polyolefin material can be passed through an extruder 602 for generation of fibers 201. The generated fibers can be passed to a quenching unite 604 for initial cooling. Then the fibers 201 can be moved forwards to the stretching unit 606. The stretching unit 606 may contain surface modifying agents. Prior to stretching and after stretching the fibers can be passed through goaded rolls 608 and 610 respectively and then moved to winder 612 for winding.
[00111] In an exemplary embodiment, the treated surface of the polyolefin material may be adhesively bonded to another substrate, or coated by paint, or a metallic coating, or printed. When the treated surface of the polyolefin material is adhesively bonded to another substrate, any suitable adhesive may be applied and then the other substrate is brought into contact with the adhesive.
[00112] In an embodiment, the suitable adhesives can include, for example, structural acrylic adhesives, epoxy adhesives, sealants, contact adhesives or thermoplastic adhesives. Examples of particularly suitable adhesives include, but are not limited to, cyanoacrylate, acrylic, epoxy, and polyurethane, silicone, antifouling coating. Alternatively any suitable self-adhesive tape may be applied to the treated surface and then the other substrate.
[00113] In an embodiment, when the treated substrate is coated by paint, any suitable paint may be used. Similarly, when the treated substrate is coated with a metallic material, any suitable metallic material may be used.
[00114] In an embodiment, the invention will now be described with reference to examples. It would be appreciated that the examples are provided for the purposes of illustrating the invention and that they in no way should be seen as limiting the scope of the above description. In the examples, the surface of a range of substrates (polyolefin materials) may be treated by various methods and bonded. After bonding, the specimens may be allowed to cure for 24 hours.
[00115] In this example the surface of samples with dimension of 25 X25 mm (length x width) of poly ethylene (PE), high density polyethylene (HDPE) and polypropylene (PP) nets were treated by various methods and were then bonded with a polyurethane.
[00116] The various Surface treatments were:
i) No treatment
ii) Pre-treatment of hot water at 60 ºC has been done
iii) After Pre-treatment by dipping for 30 Sec in chromic acid of concentration of 0.1 N to 5 N.
iv) Cold wash has been given after the treatment in point iii.
V) Polyurethane treatment has been given at 10% concentration and for 2 min with addition of coupling /wetting agent at 0.1%.
[00117] In this example the surface of samples of polypropylene (PP) and high density polyethylene (HDPE) were treated by various methods and were then bonded with antifouling paint.
[00118] The various Surface treatments were:
i) No treatment
ii) Pre-treatment of how water at 60 degree centigrade has been done
iii) After Pre-treatment by dipping for 30 Sec in chromic acid of concentration of 0.1 N to 5 N.
iv) Cold wash has been given after the treatment in point iii.
V) Antifouling paint treatment has been given at 10% concentration and for 2 min with addition of coupling /wetting agent at 0.1%.
[00119] FIG. 7 illustrates a graphical representation of Fourier-transform infrared spectroscopy (FTIR) spectrum of high-density polyethylene (HDPE) yarn.
[00120] FIG. 8 illustrates a graphical representation of a FTIR spectrum of surface of modified high-density polyethylene (HDPE) yarn.
[00121] FIG. 9 illustrates a graphical representation of a FTIR spectrum of comparative analysis of non-modified surface and modified surface of HDPE yarn.
[00122] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.
[00123] 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
[00124] The present disclosure provides an efficient technique for surface modification of a polyolefin material.
[00125] The present disclosure providesan improved for surface modification of a polyolefin material by anchoring functional group on the surface of polyolefin material.
[00126] The present disclosure providesa method for converting the nature of polyolefin’s from non-polar to polar.
[00127] The present disclosure provides a technique to develop strong interfacial interaction between oxidized/modified polyolefin’s surfaces with coating materials.
[00128] The present disclosure providesa simple and cost effective method for surface modification of polyolefin material for coating application of aquaculture and fishing nets.

,CLAIMS:1. A system for manufacturing a surface functional polymer yarn, said system comprising:
an extrusion barrel for receiving a polymer and converting said polymer into molten state for extrusion;
a die fitted at a distal end of the extrusion barrel for extruding the molten polymer into yarn; and
a quenching bath containing an oxidising solution positioned downstream of the die to receive the extruded yarn for quenching and surface modification.

2. The system as claimed in claim 1, wherein the system optionally comprises a circulation bath circuitously attached to the quenching bath for external cooling of the oxidising solution.

3. The system as claimed in claim 2, wherein the system further comprises:
first godet rollers configured to pull the surface modified yarn from the quenching bath to pass over the first godet roller and under a godet roller wiper for wiping excess oxidising solution; and
optionally, a hot air oven for evaporating any remainder solution on the surface of the yarn and drying the surface functional yarn;
second godet rollers configured to continuously pull the surface functional yarn from the hot air oven and stretch the surface functional yarn; and
optionally a winder connected to the second godet rollers for winding the surface functional yarn over said winder.

4. The system as claimed in claim 3, wherein speed of the first godet rollers is set around 50-60 MPM, and the speed of the second godet rollers is set around 65-75 MPM.
5. A method of manufacturing a surface functional polymer yarn comprises the steps of:
obtaining yarn by extruding molten polymer through a die;
quenching the obtained yarn in a quenching bath containing an oxidizing solution for surface modification of the yarn.

6. The method as claimed in claim 1, wherein the method further comprises the step of melting a polymer by heating in an extrusion barrel to yield the molten polymer.

7. The method as claimed in claim 1, wherein the method further comprises the steps of:
optionally cooling the oxidizing solution in a circulation bath;
pulling the surface modified yarn over a first godet rollers and passing under a godet roller wiper thereby wiping excess oxidising solution;
optionally drying the surface functional yarn by passing said surface functional yarn in a hot air oven to provide cured surface functional;
pulling the dried surface functional yarn from the hot air oven by second godet rollers and stretching said surface functional; and
optionally winding the core-shell yarn over a winder.

8. The method as claimed in claim 7, wherein the hot air oven is maintained at a temperature of around 80 ºC -100 ºC.

9. The method as claimed in claim 5, wherein the polymer is selected from polyethylene, polypropylene, high density polyethylene, poly(ethylene terephthalate) (PET), PVC, nylon or combinations thereof.

10. The method as claimed in claim 5, wherein the oxidising solution is selected from any or a combination of sulphuric acid, chromic acid, hydrochloric acid, potassium permanganate, sodium hypochlorite, hydrogen peroxide.

11. The method as claimed in claim 5, wherein the oxidising solution filled in the quenching bath is maintained at a temperature range from 5ºC to 20ºC.

12. The method as claimed in claim 5, wherein temperature of the oxidising solution that is filled in the quenching bath is controlled using cooled water circulating copper tube based circulation bath.

13. The method as claimed in claim 5, wherein distance between the die and level of the oxidizing solution around 10-15 cm.

14. The method as claimed in claim 5, wherein the polymer is selected from any or a combination of polyethylene, polypropylene, high density polyethylene, poly ethylene terephthalate (PET), PVC, or nylon.

15. The method as claimed in claim 5, wherein the surface functional polymer yarn is treated with at least one of a coupling agent and a wetting agent, wherein the coupling agent is any or a combination of organo-Zirconate, organo-titanate, organo-tin, and organo-aluminate.

16. The method as claimed in claim 15, wherein the coupling agent is applied from any or a combination of a solution, a vapour form, or through mechanical dispersion of a pure coupling agent or their solution or mixture in a solvent, and wherein when the coupling agent is applied from the solution, the coupling agent is applied as any or a combination of a water-based solution or a non-aqueous solution with a solvent.
17. The method as claimed in claim 15, wherein any or a combination of the coupling agent or the wetting agent is applied in a range of 0.1 % to 5% w/w, and wherein the surface functional polymer yarn is treated with an aqueous or non-aqueous solution of the at least one of the coupling agent and the wetting agent.

18. The method as claimed in claim 5, wherein the surface functional polymer yarn is made of a polyolefin material selected from any or a combination of a low density polyethylene (LDPE), polypropylene (PP), high density polyethylene (HDPE), ultra high molecular weight polyethylene (UMVVWPE), or a blend of polyolefin with a polymer.

19. The method as claimed in claim 5, wherein the surface functional polymer yarn is at least one of a fiber, a yarn, a net, or a rope.

20. A surface functional polymer yarn, wherein the surface functional polymer yarn is extruded from molten polymer through a die and quenched in a quenching bath containing an oxidizing solution for surface modification of the yarn.c