Claims:
1. A method for producing insecticide treated nets and fabrics from waste PET, wherein the method comprises the steps of:
i) producing flakes from waste PET;
ii) reducing the moisture contents of flakes;
iii) melt mixing, additivation, filtration and homogenization of the flakes to provide rPET or rPET chips;
iv) spinning of rPET melt to obtain polyester yarns and multi-filaments yarns;
v) knitting nets and fabrics from the yarns; and
vi) treating the nets with insecticides to provide insecticide treated nets.

2. A method for producing insecticide treated nets and fabrics from waste PET, wherein the method comprises the steps of:
i) producing flakes from waste PET;
ii) reducing the moisture contents of flakes;
iii) melt mixing, additivation, filtration and homogenization of the flakes to provide rPET or rPET chips;
iv) spinning of rPET melt to obtain polyester yarns and multi-filaments yarns;
v) treating the yarns with insecticides to provide insecticide treated yarns; and
vi) knitting nets and fabrics from the yarns.

3. The method as claimed in the preceding claims, wherein the production of flakes from waste PET involves segregating the waste by physico-mechanical methods based on the intrinsic viscosity of the PET.

4. The method as claimed in claim 3 wherein the intrinsic viscosity of the PET is from 0.6 to 0.8.

5. The method as claimed in claim 1 or claim 2, wherein the step of melt mixing involves
incorporation of functional additives in an extruder.

6. The method as claimed in claim 5, wherein the functional additives are blends selected from Tetrakis (2,4 – diterbutyl phenyl) – 4,4-bispheny diphosphonate ( PEPQ ), zinc salt of and Diethyl phosphinic acid, 1,3-bis-(2’-cyano-3’, 3’- diphenylacryloyl) oxy) -2, 2-bis-(((2’-cyano-3’, and 3’- diphenylacryloyl) oxy) methyl) – propane or mixtures thereof.

7. The method as claimed in claim 5, wherein the amount of the functional additives is in the range of 5000 ppm to 12000 ppm, preferably 7000 to 9000 ppm.

8. The method as claimed in claim 5, wherein the method involves adding Monoethylene glycol and DEG in the range of 0.5 to 7% w/w.

9. The method as claimed in claim 5, wherein extrusion is carried out at a temperature range of 200°C-300°C.

10. The method as claimed in claim 5 further involves melt filtration wherein the homogeneous melt is filtered in a fixed range of 50 to 5 micron.

11. The method of claim 1 or 2 wherein the homogenized rPET chips are converted to yarn by an extruder based spinning machine.

12. The method of claims 1 or 2 wherein the melt can be converted to yarn by pumping through gear pump to spinning beam to produce Fully Drawn Yarn (FDY), Partially Drawn Yarn (POY) or Polyester Staple Fiber (PSF).

13. The method as claimed 12 wherein the denier of the yarn is between 40 to 200 and number of filaments can be varied from 14 to 144.

14. The method as claimed in claim 1 or claim 2 wherein the treatment with insecticides involves addition of binders, fixative agents, and curing agents and synergists.

15. The method as claimed in claim 14 wherein the insecticides are selected from permethrin, Alphacypermethrin, Deltamethrin, Fendona, bifenthrin, Chlorofenapyr, pyriproxyfen, or mixtures thereof .

16. The method as claimed in claim 14 wherein the synergist is PBO.

17. The method as claimed in claim 15, wherein the PBO is in encapsulated form.

18. The method as claimed in claim 17, wherein the PBO is encapsulated by absorption of the PBO in proper silica / silicate materials and coating onto it before adding it in the treatment along with the insecticide.

19. The method as claimed in claim 1 or claim 2 wherein the treatment with insecticides involves curing and drying at a temperature range of 30°C to 120°C.

20. The method as claimed in claims 1 or 2, wherein the method is used for producing a Long Lasting Insecticide Nets ( LLINS ).

21. An insecticide treated polyester multifilament yarns produced by method of claims 1 or 2.

22. An insecticide treated fabric produced by method of the in claims 1 or 2.

23. An insecticide treated net produced by the process of claim 1 wherein the net is a Long Lasting Insecticide Nets ( LLINS ).

24. The insecticide treated fabric of claim 21 can be used to produce home textiles, outer garments and the like.
, Description:
Field of Invention:
The present invention relates to a method of producing Insecticide treated Long Lasting Insecticide Nets ( LLINS ) and fabrics meeting the compliances and requirements of WHOPES and other standards concerning recycled PET ( polyethylene terephthalate ) ( rPET ).

Background of the Invention:
The present invention relates to a method to produce a Long Lasting Insecticide nets (LLINs) and fabrics from recycled PET ( polyethylene terephthalate ) ( rPET ).

Many vector borne diseases including malaria are transmitted by the bite of mosquitoes in many parrts of the world. Such diseases are often fatal and therefore a number of effective prevention measures are in place, for example, sleeping under a bed net greatly reduces the chances of been bitten by mosquitoes. Ordinary mosquito nets fail to provide sufficient protection since the mosquitoes may get inside the net.

Insecticide Treated Bednets (ITNs) and Long Lasting Impregnated Bednets (LLINs) have been known to provide better and effective protection and control as they not only keep away mosquitoes but also kills them. In addition to mosquitoes, these ITNs and LLINs also protect from other insects like cockroaches, bedbugs, houseflies, fleas. These insecticides are compliant with World Health Organisation Pesticide Evaluation Scheme (WHOPES) and are WHO recommended.

Studies carried out by large WHO-coordinated study in Benin, Cameroon, India, Kenya and Sudan have shown that long-lasting insecticidal nets (LLINs) provide a significant level of protection against malaria, even where mosquitoes are resistant to pyrethroids. (https://www.who.int/malaria/news/2018/llin-study-lancet/en/).

WO2011/124227A1 proposes to blend an alkaline-sensitive insecticide and the thermoplastic polymer during production in order to make the acid an integral part of the finally produced LLIN.

CN104838060A discloses a method to produce an insecticide-containing fabric in which the polymer and more than one alkali-sensitive insecticidal active ingredient are melted together at a temperature between 120°C and 250°C or melting separately, the melt is formed into a spun thread, and a spinning oil is used in the process of spinning, the formed sewing thread is cooled, passed through a stretching system, stretched and woven to form a fabric, The fabric is then subjected to a heat setting operation characterized by washing the polymer fabric prior to the heat setting operation. The polymer fabrics, thermoplastic polymers such as polyolefins (polyethylene, polypropylene, etc.), polyesters (polyethylenterephthalates, etc.), and polyamides can be used. And compositions of fabrics made from different polymers. However, it is preferred to use polyolefins, especially copolymers of polythylene and polypropylene.

US9485990B2 discloses an insecticide-containing net like fabric containing at least one embedded insecticidally active ingredient in the polymeric matrix and having excellent wash resistance, and also to the products produced from this fabric and to their use for protecting humans, animals and plants against arthropods, particularly for controlling insects. The first step of producing the polymeric material is a masterbatch which thereafter, by melting and mixing with untreated polymer and possible further additives, is further processed into a polymeric material, which is generated in the form of pellets. The subsequent processing operation may comprise for example the resulting pellets of the polymeric materials, being processed in a processing step into shaped articles Such as for example foils, air-cushioning materials, films, profiles, sheets, wires, threads, tapes, cable and pipe linings, casings. Preference is given to a multi layered foil consisting of one layer of material according to the present invention and also of one or more layers of another material. These other materials can be for example polyethylene (HDPE, LDPE, LLDPE) or polyethylene copolymers, polypropylene, adhesion promoters such as for example ethylene-vinyl acetate copolymer, polyamide, polycarbonate, polyvinyl chloride, polystyrene, polyesters Such as for example polyethylene terephthalate or polybutylene terephthalate, cellophane, polylactide, cellulose acetate or blends thereof.

In addition, pollution created by used plastics are being a big threat to environment. The soil, canals, rivers and oceans are getting polluted by used plastics including polyester bottles, cups, pouches, films and even textiles. This polyester (polyethylene terephthalate-PET) which is used about sixty million tons per year in all applications is not biodegradable till date.

Esin Sarioglu and Hatice Kübra Kaynak in article PET Bottle Recycling for Sustainable Textiles, discloses the process of bottle-to-fiber recycling. The fiber materials generally called as recycled PET (r-PET) are especially used in carpets, blankets, clothing, and other textile applications. However, properly sorting PET bottle wastes and carefully removing impurities are essential so as to obtain similar recycled fiber quality as virgin ones. Furthermore, there are significant limitations in the use of r-PET for the production of partially oriented yarn (POY), drawn textured yarn (DTY) and fully drawn yarn (FDY) type textile yarns, microfilaments, tire cord or high quality biaxial films.

Yüksekkaya et al. (2016) investigated the properties of yarns and knitted fabrics produced by virgin PET and r-PET and cotton fibers as virgin and recycled. Yarns were produced as 100% virgin, 100% recycled, and 50%/50% virgin/recycled proportion by using rotor spinning machine. They stated that yarns produced from recycled fibers had better yarn unevenness, lower number of yarn imperfections, and better yarn quality index value. In addition, yarn tensile strength and knitted fabric burst strength were found to be lower for recycled yarns and fabrics when compared to virgin ones. However, it was suggested that yarns and fabrics produced from recycled fibers are suitable for applications where the strength of yarns and fabrics are less critical, but where uneven imperfections and handle properties required. Thus, recycled fibers are suitable for use in manufacturing of casual clothes, such as t-shirts, sweatshirts and sleepwears.

EP2381032 B1 discloses a method for preparing an insect repellant fabric characterized in that the method comprises the steps of (1) fabric making: making natural fibers to be a lining layer, making synthetic fiber multifilaments to be an outshell layer, and making polypropylene or polyethylene fiber monofilaments to be a lapping layer, wherein the lapping layer is situated between the lining layer and the outshell layer, and both the lining layer and the outshell layer are made as a meshwork stitch with a density of 3.88 to 77.7 meshes per square centimeter (25 to 500 meshes per square inch); (2) exhaust dyeing: dipping the prepared fabric into an exhaust dyeing solution and being dyed for 10 to 120 minutes at a temperature of 60 to 105°C; (3) water rinsing and centrifuge drying; (4) setting; wherein the synthetic fiber multifilaments for the outshell layer may be selected from the group consisting of polyester, polyamide, polypropylene, polyethylene, polyacrylonitrile, polyvinyl chloride and polyurethane fiber multifilaments. The patent discloses extrinsic pyrethroids applied to the fabric in an exhaust dyeing process, therefore, there is no strict requirement for the property and quality of the fibers, even the recycled synthetic fibers can be used after re-spinning process, the cost thereof is low.

There remains a need for improved and inexpensive methods to produce of insecticide treated nets and fabrics with better long lasting efficacy, durability, wash resistance and managing resistant mosquitos. Also, there is a pressing need for environmentally friendly, green and sustainable method.

OBJECT OF THE INVENTION:
It is an object of the present invention to provide a sustainable, green and environmentally friendly method for preparing insecticide treated (coated ) nets and fabrics by using recycled polyester (rPET).

It is another object of the present invention to provide a sustainable, green and environmentally friendly method for preparing insecticide treated (coated) bed nets (LLINs) by using recycled polyester (rPET).

It is a further object of the present invention to provide a sustainable, green and environmentally friendly insecticide treated (coated ) nets and fabrics by using recycled polyester (rPET).

It is yet another object of the present invention to provide a sustainable, green and environmentally friendly insecticide treated (coated) bed nets (LLINs) by using recycled polyester (rPET).

SUMMARY OF THE INVENTION:
It is an aspect of the present invention, insecticide treated (coated) nets and fabrics are provided comprising the polyester nets, wherein the polyester net is produced from recycled PET yarns and wherein recycled polyester ( rPET ) yarn is produced from post consumer polyester bottles, sheets, films and industrial waste produced during respective production.

It is another aspect of the present invention, there is provided a method for producing insecticide treated (coated) bed nets (LLINs) and insecticide treated (coated) fabrics comprising the step of preparation of nets from recycled polyester yarns, wherein the recycled polyester ( rPET) yarn is produced from post consumer polyester bottles, sheets, films etc. and industrial waste produced during respective production.

It is a further aspect of the invention to provide a method for producing insecticide treated (coated ) bed nets (LLINs) and insecticide treated (coated) fabrics from used PET bottles, wherein the method comprises the steps of:
i) producing the flakes from used PET bottles
ii) reducing the moisture contents of flakes
iii) melt mixing, additivation, filtration and homogenizing
iv) producing (i) rPET chips or (ii) polyester yarns from the rPET melt obtained from step (iii)
v) producing of polyester multi-filaments yarns
vi) knitting nets or fabrics from the polyester yarns
vii) treating the nets or yarns with WHOPES approved insecticides to provide insecticide treated nets.

In a yet another aspect of the present invention, it provides a method for producing insecticide treated nets and fabrics nets (LLINs) from used PET bottles, wherein the method comprises the steps of:
i) producing the flakes from used PET bottles
ii) reducing the moisture contents of flakes
iii) Melt mixing, additivation and filtration and homogenizing
iv) producing (i) rPET chips or (ii) polyester yarns from the rPET melt obtained from step (iii)
v) producing of polyester multi-filaments yarns
vi) knitting nets or fabrics from the polyester yarns
vii) treating the nets or yarns with WHOPES approved insecticides to provide insecticide treated nets.

DETAILED DESCRIPTION OF THE INVENTION:
The present invention is directed to provide a less expensive method to produce insecticide treated (coated ) nets and insecticide treated (coated) fabrics by using recycled polyester (rPET). It is also a green (environmentally friendly) method as it reduces pollution from polyester waste and carbon footprint.

It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

It will be further understood that the terms "comprises" and/or "comprising" used herein specify the presence of stated features, integers, steps, operations, members, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, components, and/or groups thereof.

Described herein is a method to produce insecticide treated (coated ) bed nets ( LLINs ) and insecticide treated (coated) fabrics by using recycled polyester (rPET) which involves producing different types of fibres and filament yarns.

In an embodiment of the present invention there is provided a method to produce insecticide treated ( coated ) bed nets ( LLINs ) by using recycled polyester (rPET) which involves polyester multifilament yarn and fibres, comprising the steps of:

Producing flakes of used PET bottles
The step of production of flakes from used and waste PET bottles involves controlled collection of used PET bottles (post consumer waste), waste from manufacturers (industrial waste); segregating the waste based on physico-mechanical techniques and removal of the dust, followed by special washing and cleaning by applying latest optical sorting technology and cutting under water thus producing clean rPET (Recycled polyester) flakes.

The segregation of bottles and other plastic waste is made based on the IV ( intrinsic Viscosity which represents molecular weight ). During collection and afterwards before recycling it is segregated in different lots by determining the IV ( say within range of +/- 0.01 like 0.7+/-0.01) . The physical sorting is also done depending on colour and degree of cleanliness of the waste. Therefore, the lots of nearly equal quality are taken for producing particular lot of rPET Yarns and chips.

Drying to reduce moisture content of flakes.
rPET flakes so formed in above step have a high moisture content which needs to be lowered for carrying out the further procedures.

In the present invention, for getting better uniformity in quality the flakes are stored preferably in multiple Silos and blended mechanically before they are conveyed to a crystallizer. The moisture content of rPET flakes is reduced under controlled conditions known to a skilled person in the art during crystallization followed by drying under controlled conditions through either dehumidified dry air and or IR Heater or combination of both to bring the moisture content to the desired level, preferably in the range of 10 to 200 ppm, more preferably in the range of 30 to 50 ppm.

Melt mixing, additivation ( incorporation of functional additives ) and filtration
The crystallized and dried rPET flakes are fed to extruder, which can be a Twin Screw or Single Screw extruder fitted with gravimetric or volumetric feeder and / or liquid dosing system to feed definite proportion of rPET flakes and other specialty additives with or without TiO2 in pure form or in Masterbatch ( solid or liquid ) or in dilution form in definite proportions for proper mixing. For outdoor exposure of nets and curtains cyanoacrylates type of UV absorber cum stabilizer have been used e.g. 1,3-bis-(2’-cyano-3’, 3’- diphenylacryloyl) oxy) -2, 2-bis-(((2’-cyano-3’, 3’- diphenylacryloyl) oxy) methyl) – propane grade in the range of 0.1 – 0.5% . For making the Yarn & Fiber Flame Retardant phosphorous containing additive like Zinc salt of Diethyl phosphinic acid can be used in the range of 5000 ppm to 12000 ppm , more precisely 7000 – 9000 ppm is used. Preferably the additive is an antioxidant processing stabilizer blends e.g. Tetrakis (2,4 – diterbutyl phenyl) – 4,4-bispheny diphosphonate ( PEPQ ), which is added to protect C-C chain scission in the range of 0.1 – 0.5% .

Depending on the IV of Flakes moisture content after drying is fixed and in addition MEG ( Monoethylene glycol and DEG is added in the range of 0.5 to 7% ) to reduce the IV under controlled glycolysis to bring and keep the IV in melt at the range 0.50 to 0.63 for better melt filtration to avoid excessive shear and uncontrolled degradation during melt filtration, which may otherwise happen if IV remains higher than 0.65. Moreover, the melt having IV within range of 0.50 - 0.63 gets better homogenized and have better filtration efficiency compared to high IV melt.

The melt is mixed with additives and or Masterbatches in the extruder in the temperature range of 200°C-300°C to produce a homogeneous melt (mix ).

The homogeneous melt is pumped through melt ( gear ) pump and passed through two stage continuous melt filtration system in a definitive throughput. The homogeneous melt is filtered in a fixed range of 50 to 5 micron.

Homogenization
The fine filtered molten rPET is fed to a reactor fitted with agitator, liquid and additive injection system, efficient vacuum and discharge system.

The rPET melt so obtained is modified on the basis of the required viscosity (solution and melt), molecular weight and its distribution.

Molecular weight and viscosity is reduced by glycolysis and molecular weight and viscosity is increased by the polyester chain extension through bi- and tri- functional epoxy, carboxylic acids, carboxylic acid-esters and anhydride groups and /or by catalyst in suitable proportion. Preferably functional additives are selected from Pyromellitic dianhydride ( PMDA ), Trimethyl trimellitate ( 1,2, 4 benzene tricarboxylic acid trimethyl ester ). The concentration of the functional additives is in the range of 10 to 2000 ppm, preferably 100 -1000 ppm with respect to rPET melt. For building the molecular weight with or without functional additives, poly esterification catalyst/s are used e.g. conventional catalyst like Antimony trioxide ( Sb2O3 ), Antimony triacetate [Sb(OCOCH3)3], and tetrabutoxy titanium [ Ti(OC4H9)]. Further, neoalkoxy organotitanate were also used as a repolyesterification agent to inbuild the molecular weight uniformly.

In addition to improve the binding properties of rPET chain with insecticides and binders further structural modification can be carried out by incorporating pending polar / ionic moiety e.g. 5-sulphophthalic acid and or it’s metallic salt and other proprietary additives like acrylic and acryloxy copolester.

A few of these additives like glycols, antioxidants and 5- sulphophthalic acid and or its salt are added through the throat of the extruder. The rest of the additives systems e.g. catalysts and chain extension agents are added after filtration to the conveying pipe fitted with dynamic or static mixers by high pressure side stream injection system, which enables the uniform mixing of the additives, ingredients uniformly before entering to the homogenizer.

Therefore, the molecular weight which results in increasing the intrinsic viscosity and melt viscosity to 2500 – 3200 poise by applying highly efficient vacuum and stirring / agitation in the homogenizer. The melt viscosity is preferably increased to 2700 - 2900 poise. Byproducts like water vapour, glycol are removed through vacuum. Glycol is recovered and reused. The temperature in the homogenizer is kept within the range of 230°C to 300°C , preferably in the range of 250°C to 290°C. The homogenizer is fitted with melt viscosity measuring instrument for continuous measuring the melt viscosity; which in turn provides the value of molecular weight and IV. There may be one or more ( two to three ) homogenizers in series as per the requirements of throughput and molecular weight build up with the provision of discharge at desired melt viscosity i.e. molecular weight and IV.

The residence time in the homogenizer may vary from 5 minutes to 5 hours depending on the composition, preferaby from 45 minutes to 2 hours.

As the present invention provides a method for producing mosquito nets and fabrics, the rPET melts so obtained by the above steps has an intrinsic viscosity (IV) in the range of 0.4 – 0.90, preferably 0.60 to 0.8, more preferably 0.62 –0.70. This is done on line in continuous process first reducing the IV through glycolysis and preventing thermolysis [ breaking of C-C bond in polymer chain or oxidation ] ( by addition of antioxidant cum stabilizer ) to the desired level for efficient melt filtration and rebuilding molecule with structural modification to higher desired IV. This structural modification enhances the quality of insecticide treatment, increased Wash Resistance Index and Regeneration time of the LLINs and insecticide treated (coated) fabrics.

This above steps of recycling has various advantages over normal mechanical recycling and chemical recycling in terms of cleanliness, allows adjustment of IV, structural modification with pendant functional groups, lowest wastage, lowest consumption of energy and overall Carbon foot Print Reduction unlike Chemical Recycling. This results in providing an improved quality, rPET suitable for producing both fine denier filament yarn and staple fibers and when required with functional properties for better dyeing and treatment, while prior art recycling processes (mechanical and chemical) are limited to only coarser applications.

The present inventors found that adjustment of IV to the desired range, i.e. 0.62 –0.70 is achieved by controlling the glycolysis and by judicious selection of the additives, the temperature and the time. Such optimum IV allows for improved spinning, better strength, insecticide treatment and allows better coating and impregnation.

Production of Polyester multi-filaments
The rPET melt is pumped through gear pump to spinning beam and spinned to: Fully Drawn Yarn (FDY), Partially Drawn Yarn (POY), Polyester Staple Fiber (PSF), rPET Chips (granules).

In an embodiment of the present invention there is provided a method for producing different types of polyester fibers simultaneously in the same step.

In an embodiment the rPET melt can be divided and diverted from bigger capacity reactor (homogenizer) to different paths by three ways or four ways valve simultaneously to produce the Chips, FDY, POY and PSF or any of these combination depending on the capacity and requirement.

In a preferred embodiment of the present invention the LLINs and insecticide treated (coated) fabrics are prepared from any types of recycled polyester fibers, namely fully drawn yarn (FDY), partially oriented yarns (POY) and polyester staple fibre (PSF). The POY is texturized and converted to Drawn Textured Yarn (DTY) before use employing methods known in the art.

The denier and number of filaments in FDY and DTY can be varied are as per the requirement for obtaining yarns for producing nets employing methods known in the art. The denier preferably ranges from 40 to 200 and number of filaments ranges from 14 to 144.

The present invention provides that PSF is first converted to spun Yarn in the denier range of 0.5 to 5 before knitting the nets.

In an embodiment of the present invention there is provided that the properties of the FDY, DTY and Spun yarn so obtained by the method from recycled PET, of are in the similar range to those produced from virgin PET for identical denier and number of filaments.

Further, the FDY or DTY or Spun Yarn are knitted through warp knitting machine to the net cloth (fabric) of desired gsm (gram per square meter) and number of holes per square centimeter or square inch compliant to the specification of WHOPES.

Treatment of Net ( Fabrics / cloths ) with insecticides
The above method can also be used to produce knitted net fabric or cloth made from rPET yarns are then treated (coated) with desired insecticide under WHOPES guidelines.

The treatment of the Nets / Fabrics with the insecticide casues a coating on surface as well as part impregnation within the rPET yarn.

The knitted net fabric or cloth made from rPET yarns are treated with desired insecticide suspension or dispersion through suitable machine like padding machine, spraying machine, calendaring machine etc. and then dried and cured as the case may be on line and tentering is done.

The insecticides used to treat recycled polyester nets are selected from Permethrin, Alphacypermethrin, Deltamethrin, Fendona, bifenthrin, Chlorofenapyr, pyriproxyfen, or mixtures thereof to achieve optimum knock down efficiency and with respect to resistance management. The insecticides used in the present invention are WHOPES approved. In addition to the insecticide, the process involves addition of Pyriproxyfen, which is an insecticide growth regulator and synergists like piperonyl butoxide (PBO).

Surprisingly, the present inventors found that encapsulation of Piperonyl Butoxide (PBO) achieved better retention thus improved resistance management of mosquitoes. The PBO concentration may vary from 0.1 to 2.5% wt. The encapsulation is carried out employing methods known in the art. The encapsulation of PBO is done by absorbing it in fine particle size ( 2 – 20 micron ), more specifically < 10 microns silica or silicates up to concentration of 40 % PBO. Along with PBO, 0.5-4% epoxidized Castor oil and derivatives are used for better absorption. Finally, it is ultrathin (approximately 1 micron) coated with acrylic based binder. In the present method, the encapsulated PBO is mixed along with insecticide in the treatment formulation, which results in improved controlled release, wash resistance and better service life.

The concentration of the insecticides used range from 0.1% to 5% (wt%).

In an embodiment the shape, size and construction of the recycled polyester (rPET) Nets (LLINs ) are produced as per the WHOPES Norms e.g. rectangular – single and double as well as cone type. For the resistance management, different construction of nets can also be produced where the four side walls of the Nets ( LLINs ) are constructed from recycled polyester ( rPET ) based insecticides coated nets and the roof is made by PBO and insecticide impregnated High Density Polyethylene ( HDPE ) based nets.

Physical properties like bursting strength, number of holes per square inch, storage stability, denier variation, active concentration, wash resistance and regeneration, mortality and knock down ( efficacy ) of the aforesaid types of LLINs based on recycled Polyester ( rPET ) meet the norms and specification of WHOPES.

Therefore, the present invention provides a method for producing insecticide treated nets and fabrics from used PET bottles, wherein the method comprises the steps of:
i) producing the flakes from used PET bottles
ii) reducing the moisture contents of flakes
iii) melt mixing, additivation , filtration and homogenizing
iv) producing (i) rPET chips or (ii) polyester yarns from the rPET melt obtained from step (iii)
v) producing of polyester multi-filaments yarns
vi) knitting nets or fabrics from the polyester yarns
vii) treating the nets or yarns with WHOPES approved insecticides to provide insecticide treated nets.

In a preferred embodiment the present invention provides a method for producing insecticide treated nets and fabrics nets (LLINs) from used PET bottles, wherein the method comprises the steps of:
i) producing the flakes from used PET bottles
ii) reducing the moisture contents of flakes
iii) Melt mixing, additivation and filtration and homogenizing
iv) producing (i) rPET chips or (ii) polyester yarns from the rPET melt obtained from step (iii)
v) producing of polyester multi-filaments yarns
vi) knitting nets or fabrics from the polyester yarns
vii) treating the nets or yarns with WHOPES approved insecticides to provide insecticide treated nets.

The insecticide coated fabrics can have various applications ranging from home textiles ( e.g. curtains, window screen etc.) to apparels, tents, outer part of garments for protecting from mosquitoes, fleas thus protecting the human beings from vector borne diseases. In particular, insecticide coated net fabrics may have various applications ranging from apparels to sports wear to home textiles.

The present invention is now being illustrated by way of non-limiting examples.

Examples
I. Production of flakes from waste PET bottles
Used PET bottles were collected in a controlled manner segregating the waste based on the quality by physico-mechanical techniques known to a skilled person and removal of the dust, followed by special washing and cleaning by applying latest optical sorting technology and cutting under water thus producing clean rPET (Recycled polyester) flakes. During collection and afterwards before recycling it is segregated in different lots by determining the IV in the range of +/- 0.01 like 0.7+/-0.01).

II. Reducing of moisture content of flakes.
The moisture content of rPET flakes was reduced during crystallization using known methods followed by drying through either dehumidified dry air and or IR Heater or combination of both to bring the moisture content to the desired level, preferably in the range of 10 to 200 ppm, more specifically 20 to 60 ppm.

III. Melt mixing, additivation (incorporation of Functional Additives) and filtration
The crystallized and dried rPET flakes are fed to a Single Screw extruder fitted with gravimetric or volumetric feeder and / or liquid dosing system to feed definite proportion of rPET flakes and other specialty additives with or without TiO2 in pure form or in Masterbatch ( solid or liquid ) or in dilution form in definite proportions for proper mixing. TiO2 content used 0.3%. Preferably the additive is an antioxidant processing stabilizer blends, 0.3 % of (2,4 – diterbutyl phenyl) – 4,4-bispheny diphosphonate ( PEPQ ), which is added to protect C-C chain scission.

Depending on the IV of Flakes moisture content after drying is fixed and in addition 1.4 % by wt. of MEG to reduce the IV under controlled glycolysis to bring and keep the IV in melt at the range 0.50 to 0.63 for better melt filtration to avoid excessive shear and uncontrolled degradation during melt filtration, which may otherwise happen if IV remains higher than 0.65. Moreover, the melt having IV within range of 0.50 - 0.63 gets better homogenized and have better filtration efficiency compared to high IV melt.

The melt mixed with additives and or Masterbatches in the extruder in the temperature range of 200°C-300°C to produce a homogeneous melt (mix ).

The homogeneous melt is pumped through melt ( gear ) pump and passed through two stage continuous melt filtration system in a definitive throughput. The homogeneous melt is filtered in a fixed range of 50 to 5 micron.

IV. Homogenization
The fine filtered molten rPET is fed to a reactor fitted with agitator, liquid and additive injection system, efficient vacuum and discharge system.

The intrinsic viscosity (solution and melt), molecular weight and its distribution is adjusted by adding functional additives 7000 ppm of Trimethyl trimellitate ( 1,2, 4 benzene tricarboxylic acid trimethyl ester ). It was homogenized at about 280°C, under vacuum 0.01 bar for about 45 minutes.

The rPET melts so obtained by the above steps has an intrinsic viscosity (IV) between 0.62 – 0.70.

V. Production of Polyester multi-filaments
The rPET melt is pumped through gear pump to spinning beam and spinned to: Fully Drawn Yarn (FDY), Partially Drawn Yarn (POY), Polyester Staple Fiber (PSF).
The POY is texturized and converted to DTY before use.

The filaments produced were 100 and 75 denier with 36 filaments each.

Example 1: Production of rPET based Nets coated with Deltamethrin as Insecticides and the results obtained as per WHOPES Test Protocol.
100 denier with (36 Filaments) white colour rPET FDY was produced and knitted to Net Fabric by Karl Mayer warp knitting machine. The Fabric was coated ( treated ) and impregnated with proprietary aqueous dispersion of insecticide, Deltamethrin, acrylic and polyurethane binders with fixative agents of hexamethylene diisocyanate type and curing agent. Drying and curing was advantageously performed during the process of tentering with different compartments heated to temperatures in the range of 30°C to 120°C. From the Deltamethrin coated ( treated and impregnated) net fabric, after proper conditioning rectangular rPET based bed nets were produced with dimension of 190 cm ( length ) x 180 cm ( width ) x 150 cm ( height ) through proper stitching.

Evaluation was carried out according to WHOPES recommendations and procedures for laboratory testing of long lasting mosquito nets (i.e. guidelines WHO/CDS/WHOPES/GCDPP/2013.1 and Reference Deltamethrin_coated_LN_dspecs_eval_WHO_July_2017).

Active (Deltamethrin) content on Net: 2.0 g /kg . Deltamethrin content was determined following method 333/LN/(M)/3 as mentioned in CIPAC Handbook M, P66, 2009 , Notes 5.6,7. The Active (Deltamethrin) content obtained well of within specification of +/- 25%.

Physical properties evaluation:
1. Netting Mesh Size: The mosquito net was conditioned ISO 139(1973)(WHO 2016) in a room having provision to maintain temperature at 20°C, with relative humidity of ~65% for 4 hours. The conditions were maintained throughout the measurement.

The mosquito net was kept on uniform smooth flat table, cut approximately from each net 10x10 cm and using a foot ruler marking has been carried out for a square dimension of 5 cm x 5 cm. Five replicate square markings with the same dimension was carried out at locations mentioned in CIPAC Volume-M, 454/LN/M sampling scheme (4.2.9).

The average number of complete holes per square cm is 30 holes per square cm and minimum number of holes obtained are 27 holes per square cm. Both these meet the specification of not less than 24 holes per square cm as per WHOPES specification.

2. Determination of Flammability (16 CFR 1610) (WHO 2014): The test specimen was mounted at a 45° angle in a test chamber in a frame that exposes a 38 × 152 mm area. A thread was placed across the upper end of the specimen 127 mm from the point at which a flame was applied. All the LNs did not ignite. All were classified as normal category. The Nets meet the specification of Flammability measured according to 16CFR Part 1610.

3. Storage Stability at elevated temperature: After storage at 40 +/- 2 degree C for 8 weeks the determined average active ( Deltamethrin ) content obtained as more than 98% with respect to initial active content against specified limit of not lower than 95%.

After storage at elevated temperature of 40 +/- 2 degree C for 8 weeks, it is complied with Wash Resistance Index, Dimensional stability and Bursting strength.

4. Wash Resistance Index: The wash resistance index was evaluated following MT 195 (Note 8) and obtained > 90 % against the requirement within range of 80% to 98% ( Ref. Deltamethrin_coated_LN_dspecs_eval_WHO_July_2017 ).

5. Dimensional stability of netting to washing: The shrinkage / expansion obtained 2% (average) in both the directions against the allowed limit of 5% as per specification.

6. Bursting strength: The determination was carried out using the procedure mentioned in ISO 13938-2:1999. The net was conditioned in a room having provision to maintain temperature at 20°C, with relative humidity of ~65% for 4 hours. Test area of 50 cm2 was used.

The bursting strength obtained for this 100 denier rPET based Net is 390 kPa against the required specification of minimum bursting strength of 350 kPa.

Table 1
Composition of Insecticide Treated LLINs made from rPET FDY and their Bio-efficacy . The efficacy study was conducted with susceptible strains Anopheles gambiae. Evaluation was carried out according to WHOPES reccommendation and proceedures for laboratory testing of LLINs i.e. guidelines WHO/HTM/NTD/WHOPES/2013 . 3.

Table 2
Complete testing and results of LLINs produced from rPET vs. those produced from virgin PET using same composition
Composition of Insecticide Treated LLINs made from rPET FDY and their Bio-efficacy . The efficacy study was conducted with susceptible strains Anopheles gambiae. Evaluation was carried out according to WHOPES recommendation and procedures for laboratory testing of LLINs i.e. guidelines WHO/HTM/NTD/WHOPES/2013 . 3.

Table 2-1

Table 2-2

Table 2-3

Table 3
Complete testing and results of LLINs produced from rPET vs. those produced from virgin PET using same composition (in tables 3-1, 3-2 and 3-3)

Composition of Insecticide Treated LLINs made from rPET FDY and their Bio-efficacy . The efficacy study was conducted with susceptible strains Anopheles gambiae. Evaluation was carried out according to WHOPES reccommendation and procedures for laboratory testing of LLINs i.e. guidelines WHO/HTM/NTD/WHOPES/2013 . 3 .

Table 3-1

Table 3-2

Table 3-3

Table 4 : Efficacy study with Resistant strains.
Composition of Insecticide Treated LLINs made from rPET FDY and their Bio-efficacy . The efficacy study was conducted with resistant strains Anopheles gambiae. Evaluation was carried out according to WHOPES reccommendation and proceedures for laboratory testing of LLINs i.e. guidelines WHO/HTM/NTD/WHOPES/2013 . 3 .

Results : The results are described in Table 1,2,3 and 4. All the composition pass all the tests for both rPET & PET Nets. But the comparative results show superior results for rPET compared to virgin PET. This has been possible because of adjusting IV ( Mol. Wt. ) and structural modification of rPET . This structural modification helped in getting improved quality of treatments. Because of improved treatment ( better holding and release of actives and synergists ) result better performance for rPET nets compared to virgin PET Nets.

In addition, the treatment process and composition applied are also better, thus enabled all composition to pass the WHOPES criteria.

rPET ( structurally modified during preparation ) having functional groups ( added for chain extension and structural modification ) helps in impregnation and strong binding of the insecticides compared to virgin PET ( not structurally modified ). Moreover, addition of antioxidant and stabilisers in rPET ( in molten stage at Extruder & homogenizer ) improves the performance towards high temperature stability , mechanical properties and service life.

It is neither available in virgin PET nor in regular mechanical or even Chemically recycled PET.

The Composition 3,4, 5 and 6 i.e. which have the combination of PBO and Pyriproxyfen with Deltamethrin and Alphacypermethrin are more effective in efficacy i.e. knock down and mortality both before wash and after wash against resistant strains. The detail results have been given in Table 4. As such, all the composition meet the requirements of WHOPES which are minimum 80% knock down and mortality .

Advantage of the Invention
The advantages of the present invention is that it is less expensive mosquito nets from recycled polyester yet providing excellent protection. Since the method utilized waste polyester, it is a sustainable and green process thus reducing the carbon foot print.