WO2008098572A1

WO2008098572A1 - Process and composition for synergistically enhanced insecticidal impregnation of a fabric or netting or other kind of non-living material

Info

Publication number: WO2008098572A1
Application number: PCT/DK2007/000071
Authority: WO
Inventors: Mikkel Vestergaard Frandsen
Original assignee: Vestergaard Frandsen Sa
Priority date: 2007-02-13
Filing date: 2007-02-13
Publication date: 2008-08-21
Also published as: KR20100014847A; CN101616582A; BRPI0721206A2; TW200845894A; AP2009004930A0

Abstract

A non living insecticidal material is provided, for example a fabric or netting, with a polymeric matrix into which at least one synergist is migratably incorporated before a coating with a film containing at least one insecticide.

Description

Process and composition for synergistically enhanced insec- ticidal impregnation of a fabric or netting or other kind of non-living material

FIELD OF THE INVENTION

The present invention relates to a process for providing a non living insecticidal mate- ^' rial, for example a fabric or a netting, with a polymeric matrix into which at least one synergist is migratably incorporated. The invention, also, relates to such a non-living material.

BACKGROUND OF THE INVENTION

A number of different insects cause substantial problems as vectors and transmitters of infectious diseases affecting humans, and tremendous efforts are invested in controlling these insects. Efforts have been concentrated on controlling insects belonging to the order Diptera (covering mosquitoes, gnats, black flies, tsetse flies and other biting flies), Hemiptera (covering bed bugs) and Siphonaptera (covering fleas). Methods to control these insects include treating inner and outer surfaces of walls, air spraying, as well as impregnation of curtains and bednets. The impregnation of curtains and bed- nets has the advantage that the surface area to be treated is much reduced compared to a surface spraying of a house. The impregnation of the bednet reduces nuisance during sleeping and has been shown to be effective even if the net is slightly torn due to use.

The effect of a netting or fabric impregnated with a pyrethroid is partly based on the fast insecticidal property of these insecticides, but also on the repellent effect inherent in most of these insecticides. Tests have shown that an impregnated bednet reduces the number of mosquitoes entering the room with up till 75 %. Thereby, the net also provides some protection for other persons sleeping in the same room even they are not covered by the net.

Large scale field experiments with nettings have shown that they may reduce malaria infection rate as measured directly or indirectly as gross children mortality. Accord- i ingly, netting has been selected as a priority area for the campaign against malaria and other mosquito born diseases by WHO, the World Health Organization.

In some areas mosquitoes are resistant to pyrethroids. One of these resistance types, so-called knock down resistance or KDR, also provides resistance to the repellent ef- fec. This allows the mosquitoes to rest for a longer time on the net and thus to accumulate a lethal dosage of the insecticide, but it also gives the mosquitoes the possibility to bite before dying. Another form for resistance is metabolic resistance, where the insect has enzymes counteracting the insecticidal effect. In this case, , a synergist, for example piperonyl butoxide (PBO), can be added to the net with great advantage.

Using synergists in coatings in connection with mosquito nets or fabrics is disclosed in Chinese patent application CNl 099825 by Ye Qian, in International patent application WO 90/14006 by Mooney et al., WO06128870 by Karl et al, and WO06128867 by Koradin et al, in Japanese patent applications JP 02-062804, JP 04-185766, JP 06- 346373, and JP 07-316003 by Fujita et al., US patent No. US 5,503,918 by Samson, and US patent application No. US20070009563A1 by Hataipitisuk. Incorporating a synergist in a polymer matrix together with an insecticide is disclosed in US patent application No. US20060288955 by Albright et al. and in International patent appica- tion WO 00/40084 by Kellerby and Fletcher.

The general and world wide preferred materials for bednets are cotton and polyester. Nets of polyester have been chosen by the WHO as the favourite material for bednets due to their better strength, their cotton like feeling and reduced fiammability. Opposite to that, nets of nylon are flammable, and polyethylene nets, like the Sumitomo® net with tradename Olyset®, are stiff. The Olyset® net is based on a mono-filament Polyethylene (polyethene) fibre into which insecticide is incorporated during formation of the fibre. This method of incorporating the insecticide into the fibre is known not to be applicable for polyester (Polyethylene Terephthalate, PET) fibres due to the high melting temperature of 250°C for polyester, which is destructive for the pyrethroids. WO 01/37662 by Skovmand discloses impregnated nettings or fabrics for insect or tick killing and/or repellent of an insect or tick comprising an insecticide, preferably a pyrethroid, and a film forming component reducing the wash off and degradation of the insecticide component from the netting or fabric by forming a water-resistant film. The film forming component comprises paraffin oil or wax derivatives, silicon derivatives, silicon oils or wax derivatives, and polyfluorocarbon derivatives in addition to a polymeric backbone fixative. The netting or fabric is impregnated by adding a solution or a water emulsion of an insecticide and/or repellent and a film forming component. The insecticide is dissolved in an organic solvent in the process for impregnation of a fabric or netting.

The composition and impregnaton method as disclosed in WO 01/37662 has been used as a basis recipe for the mosquito net with the tradename Permanet® by Vester- gaard Frandsen®. This net exhibits today the highest standard of wash resistant mosquito nets worldwide and is the preferred net in WHO aid activities where mosquito nets are involved.

Thus, it would be desirable to provide a fabric or net of high standard which is efficient against insecticidal resistance and which has the potential of being as successful as PermaNet® with regard to wash resistance.

DESCRIPTION OF THE INVENTION

It is therefore the object of the invention to provide an improved non-living insecticidal material, especially fabric or net, with an insecticidal impregnation and a synergist.

This object is achieved with a non-living insecticidal material, for example a fabric or netting, with a polymeric matrix into which at least one synergist is migratably incorporated. The surface of the matrix is coated with a coating containing at least one insecticide. The object is also achieved with a process for providing a non living insecticidal material, for example a fabric or netting, with a polymeric matrix into which at least one synergist is migratably incorporated before a coating with a coating containing at least one insecticide.

By incorporating the synergist in the polymer matrix with the ability to migrate to the surface of the matrix, a product is provided that leaves open a high number of choices for the final insecticidal composition with which the matrix is coated. For example, it maybe coated with a wash resistant polymer film as it is used for PermaNet®.

In principle, one or more insecticides may be incorporated in the polymer matrix as well as further synergists. La this case, it is important to take in to account the migration speed of the synergist or synergists in the matrix and the migration speed of the further insecticide or insecticides. For example, this may be regulated by a proper choice of selectively working migration promoters and migration inhibitors.

In order for the synergist to be effective, it has to be assured that the synergist is able to migrate also from the matrix surface to the surface of the coating. Appropriate migration promoters and/or migration inhibitors may also be used in this case.

A preferred combination is a polymer matrix with synergist, for example PBO, incorporated in the matrix material but without insecticides in the matrix, and with an insecticidal coating, for example containing deltamethrin, on at least part of the surface of the polymer matrix. Essential, in this connection, is that the matrix is provided insecticide-free but with synergist in an initial state. Therefore, in a further embodiment, the matrix of the non-living material is insecticide-free at least until the coating process. Though, the matrix is free from incorporated insecticides in an initial state, the insecticide may migrate into the polymer matrix from the coating after a subsequent coating step, which is still within the scope of the invention. Therefore, in a further embodiment, the matrix has an initial, insecticide-free, solid state, where it contains at least one synergist, and wherein it has a final, solid state, where it contains an insecticidal coating. Ia one embodiment, the matrix may contain one or more synergists, for example PBO, but no insecticide, whereas the coating does not comprise a synergist but comprises one or more insecticides, for example deltamethrin.

In a practical embodiment, the polymer matrix is formed by extrusion of molten thermoplastic polymer through an extrusion nozzle. The synergist is added to the molten polymer through a channel in or upstream of the extrusion nozzle. This may in certain combinations be critical, especially, if the matrix is made of polyester, a preferred material for fabrics and nettings. This is so, because the melting temperature of polyester is around 250°C, which is far above the temperature, where a synergist like PBO stays intact. However, the degree of decomposition of the synergist, for example PBO₅ is not only dependent on the temperature but also dependent on the time for which the PBO is exposed to the temperature, in as much as the decomposition process behaves gradual. Having realized this, it has been recognized, as well, and experimentally verified that a synergist, like PBO, can withstand a high temperature, for example 180°C or higher, above the normally believed decomposition temperature, if the time for the exposure to that temperature is kept short.

Thus, in order to minimize the exposure time for the high temperature, a special principle of an extrusion nozzle has been invented. This principle is a nozzle with a channel through which the synergist is added into the molten polymer during the extrusion process, wherein the channel is provided at a short distance upstream of the nozzle exit. In this context, the term "short distance" is to be understood as a distance that results in a temperature increase in the synergist and a time lapse at this temperature which leaves a still sufficient amount of intact synergist in the extruded matrix. For example, the distance may be chosen to yields a maximum temperature increase in the synergist and a maximum time of exposure of the synergist to this temperature increase, wherein the maximum temperature and the maximum time are limited by predefined upper levels.

How much this "sufficient amount" is, depends on the synergist and the acceptable level of decomposition. In certain cases, a decomposition of 99% can be acceptable, if the 1% remaining synergist is still within the range of effective amounts to counteract insecticidal resistance for a long term. In other cases, a decomposition rate of less than 90% may be acceptable. Thus, the invention provides a method for incorporating synergists in thermoplastic polymers, despite the fact that the melting temperature of the polymer is far above the decomposition temperature of the synergist, hi experiments, it has surprisingly turned out that for polyester, more than 50% of the synergist stays intact despite an extrusion temperature of more than 25O⁰C.

In a preferred embodiment, the channel is provided in the side of an extrusion, for example within a few mm or cm from the nozzle exit. This implies that the synergist is first subjected to the temperature of the polymer when it enters the nozzle. For example, the nozzle may be surrounded by a ring-formed synergist supply conduit injecting synergist into the molten polymer substantially over the entire rim of the polymer stream through the nozzle.

This leaves also the possibility of cooling the synergist before injection, such that the temperature increase of the synergist due to the uptake of heat from the polymer accelerates the hardening and cooling of the polymer. In addition, the extruded polymer may be actively cooled at a short distance downstream of the extrusion nozzle, for example by a cold air jet.

The process, where the matrix is coated, may be achieved by the method as disclosed in WO 01/37662 concerning the impregnation of a fabric or netting so as to impart insect killing and/or repellence properties, comprising:

a) preparing a solution or a water emulsion of an insecticide and/or a repellent and a film forming component reducing wash off and degradation of the insecticide component from the non-living material by forming a water and optionally oil resistant film on the surface of the non living material, for example around the fibres, and applying the solution or emulsion to the non living material, or

b) preparing a first solution or water emulsion of an insecticide and/or a repellent and preparing a second solution or water emulsion of a film forming component reducing wash off and degradation of the insecticide component from the non living material by forming a water and optionally oil resistant film on the surface of the non living material, for example around the fibres, and applying the solution or water emulsion of the insecticide and/or repellent on the non-living material and then applying the solution or emulsion of the film forming component to the non living material,

wherein said film forming component comprises a polymeric backbone fixative and one or more components selected from paraffin oils or waxes, silicons, silicon oils or waxes, and polyfluorocarbons, or derivatives thereof.

In a further embodiment, the film forming component comprises a mixture of components selected from paraffin oils or waxes, silicons, and silicon oils or waxes, and polyfluorocarbon or derivatives thereof, preferably a mixture of a polyfluorocarbon and a paraffmic oil or a mixture of a polyfluoroalkyl and a polysiloxan. For example, the silicon oil or wax is a polysiloxan.

hi a further embodiment, the polyfluorocarbon, paraffin oil or wax, silicon, silicon oil or wax, or derivatives thereof is/are attached to the polymeric backbone. For example, the polymeric backbone fixative is a resin, polyurethane or polyacryl.

hi a preferred embodiment, the film forming component comprises a polymeric backbone fixative polymerizing into a film with polyfluorocarbon side chains on the polymeric backbone in a drying process or in a curing process or in a drying and curing process of the non living material.

The combined solution or emulsion, where the insecticide composition is incorporated in the wash resistant agent before application to the non-living material, may be used as a composition for impregnation or as part of a composition for impregnation, in as much as it may be mixed with other components. Such components may be other insecticides, synergists, UV protecting agents, preservatives, detergents, fillers, impact modifiers, anti-fogging agents, blowing agents, clarifiers, nucleating agents, coupling agents, conductivity-enhancing agents to prevent static electricity, stabilizers such as anti-oxidants, carbon and oxygen radical scavengers and peroxide decomposing agents and the like, flame retardants, mould release agents, optical brighteners, spreading agents, antiblocking agents, anti-migrating agents, migration promoters, foam-forming agents, anti-soiling agents, antifouling agents, thickeners, further biocides, wetting agents, plasticizers adhesive or anti-adhesive agents, fragrance, pigments and dyestuffs and other liquids including water or organic solvents.

The impregnating composition may also be partly absorbed in an absorptive fabric, which may prolong the insecticidal activity and improve the wash resistance, hi the case of the fibres being multifilament yam, insecticide may be trapped between the filaments, leading to a higher wash resistance of this trapped insecticide. The method according to the invention is applicable for hand dipping, however, it has proved to be especially suitable for industrial production.

The protective composition according to the invention relates to a single component or a mixture of components giving water or water and oil resistance. One or several detergents may be added to increase wettability of the agent to the fabric, to stabilise emulsions used, or to increase fixation. A cross-linking agent or a catalyser may be used to increase fixation. The pesticidal composition and the protective composition may be added successively (process a) or in one process (process b). An improved finish and curing may be obtained by finally passing a heated surface such as an iron or a heated roller or heating with hot air.

The polymeric backbone is discussed in more detail in WO 01/37662.

Alternative insecticidal coatings applicable in connection with the invention is disclosed in WO 2006/092094 by Liu et al. concerning a net/fabric coating containing a pesticide, an aqueous adhesive, like a waterborne polyurethane latex or polyacrylate latex, and a cross linking agent, like an epoxy polymer cross linking agent. A number of different formulations - also applicable in connection with the invention - are disclosed in WO 2006/092094, which, more specifically, disclosed a finishing liquid for repelling and killing mosquito/insect, whose formulation (based on mass percent) comprises: pesticide and/or repellent, 0.05%-40.00%; adhesive 5.00%-40.00%; cross-linking agent 0.025%-1.50%; and the rest is water, all the components amount up to 100%.

The pesticide in WO 2006/092094 is an aqueous pesticide with an effective content of 1-50%, and said aqueous pesticide is prepared from one or two of the following substances: deltamethrin, cyfiuthrin, cyhalothrin, cis-cypermethrin, peπnethrin and eto- fenpox;

The repellent in WO 2006/092094 is an aqueous repellent with an effective content of l-50%_> and said aqueous repellent is prepared from one or two of the following substances: diethyltoluamide (DEET), dimethyl phthalate and peπnethrin;

The aqueous dosage form of said pesticide and repellent in WO 2006/092094 includes one or two of the following dosage forms: wettable powder, water dispersible powder, water dispersible suspension, water dispersible tablet, emulsion in water, microcapsule suspension, and water dispersible granule;

The adhesive in WO 2006/092094 is an aqueous adhesive with a solid content of 40- 50%, which contains one or two of the following substances: polybutadiene latex, wa- terborne polyurethane latex, polyacrylic acid latex, polyacrylate latex or vinyl acetate latex;

The cross-linking agent in WO 2006/092094 contains one or two of the following substances : epoxy polymer crosslinldng agent, methyl-etherified hexahydroxymethyl melamine resin primary condensate crosslinking agent, multi-functional aziridine crosslinking agent, various hydroxymethyl crosslinldng agents, a crosslinking agent consisting of hydroxyethyl and epoxy groups, and an acetate crosslinking agent of polycondensate of epoxy chloropropane and hexandiamine.

Preferably, the insecticide in connection with the invention is a pyrethroid, preferably deltamethrin or permethrin, but other pyrethroids may apply as well, as disclosed as a list in WO 01/37662. However, the invention applies as well in connection with ca- bamates or organophosphates in the composition for impregnation. A more extensive list of possible insecticide is found in WO 01/37662 or in WO 06/128870 also containing examples of repellents.

In addition, the term insecticide applies as well to insecticide combinations in the composition for impregnation according to the invention. For example, a pyrethroid may be combined with carbamates or organophosphates in order to combat resistant insects as well. Also, two or more insecticides may be applied on various parts of the net or fabric, for example by printing or spraying techniques, and not mixed and used homogeneously, which can be beneficially with respect to toxicological and registration reasons. Where nets are used in mass campaigns, the alternative or supplemental insecticide may also be an insecticide with a sterilising effect thus to sterilise the mosquitoes and avoid the next generation of mosquitoes. Such insecticides can be of the benzoyl urea group or triazins.

Further possible combinations include metaflumizone as disclosed in WO 06/127407, N-arylhydrazine as disclosed in WO06128870 or derivatives of 1-Phenyltriazole as disclosed in WO06128867, for example combined with a pyrethroid.

hi addition, or alternatively, insecticides may be combined with synergists in the coating, for example piperonyl butoxide, Sulfoxide, Tropital, Bucarpolate, ethion, profen- ofos, or dimethoate, Piperonyl Cylonene, TPP, Di-ethyl maleate, NIA-16388 (NIA), S-421, MGK-264 (bicycloheptenedicarboximide), S,S,S-tributyl phosphorotrithoate (DEF), - N-Octylbicyclohepteiie dicarboxaminde, Sesamin, Sesamolin, or Sesamex.

A further alternative for a coating in connection with the invention is disclosed in US2007009563, wherein formula of solution according to various embodiments of the present invention comprises 4 portions as follows: 1. Insecticide from pyrethroid group such as deltamethrin, esfenvalerate, ethofenprox, biphenthrin, permethrin, and cyhalothrin which are quickly active and have a high boiling point. 2. A thread stabilizing enhancer, for example, a compound of perfiuoro acrylate, resin, adhesive, and polyacrylate. 3. Thickeners such as starch, gum, and titanium dioxide. 4. Solvents, for example, water. Non living material

In the following, a number of examples of non-living material in the context of the invention are given: a textile material or plastics material selected from the group consisting of yarn, fibers, fabric, knit- goods, nonwovens, netting material, foils, tarpaulins and coating compositions. The netting material, for example, may be prepared by circular knitting or warp knitting, or by sewing parts of a netting to obtain the desired nettings. The textile material or plastics material may be made from a variety of natural and synthetic fibers, also as textile blends in woven or non-woven form, as knit goods, yarns or fibers. Materials for synthetic fibers are, for example, polyamides, polyesters, polyacryl nitriles, polyolefines, for example polypropylene or polyethylene, Teflon. Polyamides, polyolefins and polyesters, for example polyethylene terephtha- late, are preferred.

Application of textile material or plastics material includes bedclothes, mattresses, pillows, duvets, cushions, curtains, wall coverings, carpeting and window, cupboard and door screens, geotextiles, tents, inner soles of shoes, garments, such as socks, trousers, shirts, uniforms, horse blankets, bed nets, covering in agriculture and viniculture; fabrics or nettings for packages, wrapping sacks; containers for food, seeds and feed; paper; construction materials, furniture, leathers, vinyl articles, electric wires and cables.

Most preferred are fabrics or nettings made from polyester, because polyester nettings have a cotton-like feeling and low flamrnability. These are also reasons, why these netting are preferred by the WHO. Pn this regard, it is emphasized that the invention is one embodiment is directed towards application in connection with a 75, 100 or 150 denier 36 filament deltamethrin impregnated polyester netting, like Permanet 2.0.

Further special applications in connection with the invention are as,

- fencing, such as disclosed in WO03003827,

- pesticidal blanket, such as disclosed in WO03055307,

- protective cover for food and water storage containers, such as disclosed in WO03090532,

- air cleaning canopy, such as disclosed in WO2006024304, - tarpaulins, such as disclosed in WO 03/063587.

Insects

The aim of the invention is to control and/or to combat a. variety of pests, such as ticks, coclσoaches, bed bugs, mites, fleas, lice, leeches, houseflies, mosquitoes, termites, ants, moths, spiders, grasshoppers, crickets, silverfish, and other flying and crawling insects.

The applying process

The applying of the insecticidal impregnation composition may be performed by padding, dip washing, spraying, printing techniques, for example transfer printing or analogous to inkjet printing.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail with reference to the drawing, where FIG. 1 illustrates a polymer matrix with synergist in the matrix and a coating with insecticide,

FIG. 2 illustrates a coated matrix in the form of a fibre FIG. 3 is an illustration of the extrusion process,

FIG. 4 is a more detailed graph of a further example of an extrusion nozzle, FIG. 5 illustrates a matrix in the form of a fibre coated with a fragmentary film.

DETAILED DESCRIPTION / PREFERRED EMBODIMENT

FIG. Ia illustrates a non living object 1 with synergist 2 in the matrix 3 - illustrated stylistically as dots 2 although the synergist 2 may be homogeneously distributed in the matrix. The matrix 3 is coated with a film 4 containing an insecticide 5 — illustrated stylistically by triangles 4, although the insecticide may be distributed homogeneously in the film coating. When the matrix 3 is coated with such film 4, the synergist 2 is migrating through the film 4 to the surface 6 of the non living object 1, which is illustrated in FIG. Ib. Also, the insecticide 5 is migrating to the surface 6, such that the surface 6 contains insecticide 5' as well as synergist 2' for uptake by insects. In addition, as illustrated in FIG. Ib, if the matrix is migratable for the insecticide 5, insecticide 5 ' ' may migrate from the film 4 into the matrix 3. FIG. 2 illustrates a matrix 3 in the form of a fibre coated with a film 4. The drawing only illustrates the principle and is not to scale. The coating of the matrix, such as a fibre, may be in the form of a continuous film, as illustrated in FIG. 2, or the coating maybe in the form of fragments, as illustrated in FIG. 5. Such fragments maybe in the form of a film, if a film forming component is used. Achieved may such a fragmentary coating be by spraying techniques, for example.

In the following, the product and the extrusion process is described in more detail. FIG. 3 illustrates an extruder with housing 8 inside which a piston 9 is forwarded in the direction of an extrusion nozzle 10, through which the molten polymer matrix 4 is pushed for extrusion in order to produce the extruded product 11, for example a polymer fibre. At a short distance upstream of the nozzle 10, a conduit 12 is connected to the housing 8 for feeding of synergist 2 from a tank 13. The synergist enters the molten polymer 4 and is exposed to the high temperature of the molten polymer during the time lasting from entering the housing 8 until the extruded polymer is cooled down.

It should be mentioned, at this point, that the extrusion principle with the piston may easily be replaced with an extrusion screw or other means by which the molten polymer can be extruded. As an alternative, also, the conduit 12 may be part of the nozzle itself, only requiring that the PBO enters the molten polymer and is distributed therein. In this connection, it is not essential that a homogeneous distribution is achieved as long as the PBO enters the matrix and is accumulated in the matrix such that a long lasting effect is achieved by the migration through the matrix and the film onto the surface of the non living material.

An alternative principle of the nozzle is illustrated in FIG. 4. In this case, the synergist is added to the molten polymer in a ring- formed supply conduit 14 around the extrusion nozzle 10, where the synergist 2 is added to the polymer 4 in the periphery 15 of the polymer 4 stream from the conduit and through a number of injection holes in the nozzle 2. This may result in a non-homogeneous distribution of the synergist 2 in the extruded fibre 11. Due to the migration of the synergist 2, this inhomogeneous distribution may change with time into a more homogeneous distribution due to a gradient governed migration of the synergist. In certain cases, a relatively high concentration may be achieved by this method near the surface of the final product, for example a fibre. This may be acceptable, if only the gradual migration from the matrix through the surrounding film leads to a long lasting release of the synergist. An inhomogene- ous distribution of the synergist in the matrix, as indicated in FIG. 4 by the uneven distribution of dots, with most of the synergist in the rim^'part of the extruded product, may be an advantage due to the fact that the outer part 16 of the extruded article 11 is cooled first after extrusion, which implies a shorter exposure of the synergist to the high temperature in the rim part 16 of the matrix than in the central part 17 of the matrix. Thus, a relatively higher part of the synergist stays intact in the rim part of the matrix. In addition, there may be a temperature profile of the molten polymer inside the nozzle, such that the rim part 18 of the polymer flow 19 has a lower temperature than the central part 20 of the polymer 4. Also, this fact reduces a decomposition of the synergist due to the high temperature. In order to delay the heating of the synergist as much as possible, the ring-formed conduit 14 may be thermally isolated from the nozzle 2 wall 22 by isolation material 21.

The time between adding of the synergist and until the extruded polymer has cooled down to a temperature that is not critical for the synergist is a crucial factor for the decomposition of the synergist as well as the temperature. If the temperature is below the critical temperature for decomposition of the synergist, this time is not critical at all. If the temperature is around the critical decomposition temperature of the synergist, care has to be taken that the exposure to the temperature is kept relatively short. If the temperature is far above the critical temperature of the synergist, the time for which the synergist is exposed to the temperature has to be kept very short. During experiments in an extruder, it has been possible to verify that it was possible to incorporate as much as 70% intact PBO in a polyester fibre by extrusion. As the temperature of the molten polyester was 290°C, which is far above what is believed to be a critical decomposition temperature of PBO, the result is astounding. It has been proposed to incorporate PBO in a polyethylene (polyethene) matrix, as the melting temperature of polyethylene of 12O⁰C is rather low. However, at temperature above the melting temperature of 250°C of polyester (Polyethylene Terephthalate, PET), which is far above the boiling point at 155⁰C of PBO, PBO is believed not to be able to stay intact. This contradiction between theory and practice is not only an advantage for synergist incorporation in polyester, but also an advantage for synergist incorporation in polyethylene, in as much as polyethylene, often, is extruded at temperatures far above the above mentioned 120⁰C. For example, experiments were performed, where polyethylene was extruded at temperatures above 250°C. Thus, the experiments according to the invention have verified that it is possible to incorporate intact synergists, especially PBO, into a polymer matrix above 16O⁰C, for example at temperatures above 18O⁰C or even above 200⁰C.

In order to keep the time for the high temperature exposure of the PBO short, the extruded polymer may be actively cooled, for example by cold air jets, or by extrusion into a cooling liquid.

As discussed above, the method according to the invention may be used for fabrication of a large variety of objects. However, the preferred application is for production of insecticidal fibres for fabrics or, especially, insecticidal nettings. In the following, steps of a fabrication process for insecticidal nets is described

The knitting, cleaning, colouring, sewing and packing of nettings

Drawn texturised polyester fibre yarn (DTY Polyethylene Terephthalate, PET) is delivered in rolls from a supplier, where the fibres consist of 36 polyester filaments. The delivered fibres are knitted into continuous nets. Before the nets are optionally coloured, sewed into the right dimensions and packed, they are subjected to the impregnation process.

The impregnation process

In the two-step process a), the solution of the insecticide in the solvent, preferably a pyrethroid, especially deltamethrin, is mixed with alcohol or glycol (ethyl-alcohol, propylenglycol, etc.) and the fabric or netting passes through a bath with the insecticidal liquid, or the insecticidal liquid is applied to the fabric or netting by spraying, printing or other techniques. Especially suited for industrial production, to reduce the amount of solvents used in the process, the fabric or netting passes two rollers or a roller against a fixed surface to squeeze off as much as possible of the fluid. The con- centration of the pyrethroid in the solution is calculated on the amount of solution remaining in the fabric or on the netting after this process. The fabric or netting is then dried, e.g. by a passing air stream or in an oven. The fabric and especially the netting may be kept fixed under this process in order not to change shape or in order to apply a certain shape to the netting. The temperature used in the drying process must be below 22O⁰C, and preferably below 100°C in the composition itself. After drying, the fabric or netting passes a second bath, spray station, printing station, or the like, where a solution or emulsion of the wash resistant agent is added. A cross binding or a catalysing agent may be added. This emulsion with polyfluorocarbon forms a continuous film during evaporation of the water.

hi the one-step process b), which is the preferred method, the solution of the insecticide in the solvent is mixed with alcohol or glycol (ethyl-alcohol, propylenglycol, etc.). This mixture is then mixed under stirring with an organic solution or a water emulsion of the wash protective agent, optionally with the addition of catalytic or cross binding agent and an acidifier. Detergents maybe added to stabilise the organic solution of the pesticide in the water emulsion and to ease wetting. After completely wetting, the fabric or netting may pass a press, e.g. comprising two rollers, to reduce the amount of composition absorbed. Alternatively, surplus composition may be removed by centri- fuging. The fabric or netting is finally dried, as described above, or dried by passing a warm surface, such as over a warm roller. Alternatively, the fabric may be partly or totally air dried, e.g. under vacuum, and then passed between one or two heated rollers or a roller and a heated surface. For the netting, the temperature during the drying process has to be chosen such that the insecticide is not decomposed. This final drying at elevated process also serves to accelerate the orientation of the molecules of the wash protective agent to form a homogenous wash repellent film. This process is often named as the "curing".

The impregnation process for a mosquito net

In a preferred embodiment, especially used for mosquito nets, deltamethrin is dissolved/dispersed in a solvent, for example acetone and ethanol. The film forming component is dissolved/dispersed in water together with a stabiliser/emulsifier, where also an acidifier is used. The final mixture with the insecticide and the film forming agent is applied to the net by padding, where the net run over rollers at a controlled speed. For a net as PermaNet®, the initial pick up weigh is selected so that after drying, the final deltamethrin content is 55mg/m² net. The netting is dried and subject to a curing process at temperatures below the temperature, where the insecticide decomposes at a critical rate. Decisive in this case is not necessarily the temperature of the heating medium, for example the roller or hot air heater, but the temperature in the coating, as the latter determines the decomposition of the insecticide. Thus, the temperature of the heater may be higher than the decomposition temperature of the insecticide, especially as long as the coating is not dried, as the evaporation of the solvents/water would have a cooling effect on the insecticidal film.

Claims

1. A process for providing a non living insecticidal material, for example a fabric or a netting, with a polymeric matrix into which at least one synergist is migratably incorporated, characterised in that the process comprises coating the surface of the matrix with a film containing at least one insecticide, and wherein the synergist in migratably incorporated in the matrix before the coating.

2. A process according to claim 1, wherein the matrix of the non-living material is insecticide-free at least until the coating step.

3. A process according to claim 1 or 2, wherein the coating is performed with a synergist- free coating material.

4. A process according to any preceding claim, wherein the synergist in blended into the polymer matrix in a liquid phase state of the polymer.

5. A process according to any preceding claim, wherein the polymer of the matrix is a thermoplastic polymer.

6. A process according to any preceding claim, wherein the polymer matrix is formed by extrusion of molten thermoplastic polymer through an extrusion nozzle, wherein the synergist is added to the molten polymer through a channel in the extrusion nozzle or upstream of the extrusion nozzle, the channel being provided at a short distance upstream of the nozzle exit, the distance between the channel and the nozzle exit being chosen to result in a still sufficient amount of intact synergist in the extruded matrix.

7. A process according to claim 3, wherein the sufficient amount is at least 1% of the synergist.

8. A process according to claim 3, wherein the sufficient amount is at least 10% of the synergist.

9. A process according to claim 3, 4, or 5, wherein the channel is provided in the side of the nozzle.

10. A process according to any preceding claim, wherein the synergist is added to the polymer in the periphery of a polymer stream through the nozzle.

11. A process according to any preceding claim, wherein the synergist is added to the molten polymer through a ring-formed supply conduit around the extrusion nozzle through a number of injection holes in the nozzle.

12. A process according to any preceding claim, wherein ring- formed conduit 13 is thermally isolated from a wall of the nozzle by isolation material.

13. A process according to any preceding claim, wherein the polymer is extruded at an extrusion temperature of more than 160⁰C.

14. A process according to any preceding claim, wherein the polymer is polyester.

15. A process according to any preceding claim, wherein the film comprises an insecticide from pyrethroid group, a thread stabilizing enhancer from the group of per- fluoro acrylate, resin, adhesive, and polyacrylate, a thickener form the group of starch, gum, and titanium dioxide and water as a solvent.

16. A process according to any preceding claim, wherein coating of the non living material, comprises:

a) preparing a solution or a water emulsion of an insecticide and/or a repellent and a film forming component reducing wash off and degradation of the insecticide component from the non-living material by forming a water and optionally oil resistant film on the surface of the non living material, for example around the fibres, and applying the solution or emulsion to the non living material, or b) preparing a first solution or water emulsion of an insecticide and/or a repellent and preparing a second solution or water emulsion of a film forming component reducing wash off and degradation of the insecticide component from the non living material by foπning a water and optionally oil resistant film on the surface of the non living material, for example around the fibres, and applying the solution or water emulsion of the insecticide and/or repellent on the non-living material and then applying the solution or emulsion of the film forming component to the non living material,

wherein said film forming component comprises a polymeric backbone fixative and one or more components selected from paraffin oils or waxes, silicons, silicon oils or waxes, and polyfiuorocarbons, or derivatives thereof

17. A process according to claim 16, wherein the film forming component comprises a mixture of components selected from paraffin oils or waxes, silicons, and silicon oils or waxes, and polyfmorocarbon, or derivatives thereof.

18. A process according to claim 16 or 17, wherein the film forming component comprises a mixture of a polyfluorocarbon and a paraffinic oil or a mixture of a poly- fluoroalkyl and a polysiloxan.

19. A process according to anyone of the claims 16-18, wherein the silicon oil or wax is a polysiloxan.

20. A process according to anyone of the claims 16-19, wherein the polymeric backbone fixative is a resin, polyurethane or polyacryl.

21. A process according to anyone of the claims 16-20, wherein the polyflurocar- bon, paraffin oil or wax, silicon, silicon oil or wax, or derivatives thereof is/are attached to the polymeric backbone.

22. A process according to anyone of the claims 16-21, wherein said film forming component is polymerizing into a film with polyflourocarbon side chains on the polymeric backbone in a drying process or in a curing process or in a drying and curing process of the non living material.

23. A process according to anyone of the claims 16-22, wherein the film forming component is mixed with an emulsifier or stabiliser or both in water solution before mixing with the insecticide solvent or emulsion.

24. A process according to any preceding claim, wherein the insecticide is a pyre- throid.

25. A process according to any preceding claim, wherein the flim comprises a pesticide, an aqueous adhesive and a cross linking agent, wherein the aqueous adhesive is a polybutadiene latex, waterborne polyurethane latex, polyacrylic acid latex, polyacrylate latex or vinyl acetate latex, and wherein the cross linking agent contains one or two of the following substances : epoxy polymer crosslinking agent, methyl- etherified hexahydroxymethyl melamine resin primary condensate crosslinking agent, multi-functional aziridine crosslinking agent, various hydroxymethyl crosslinking agents, a crosslinking agent consisting of hydroxyethyl and epoxy groups, and an acetate crosslinking agent of polycondensate of epoxy chloropropane and hexandiamine.

26. A non-living insecticidal material, for example a fabric or a netting, with a polymeric matrix into which at least one synergist is migratably incorporated, characterised in that the surface of the matrix is coated with a film containing at least one insecticide.

27. A non living material according to claim 26, wherein the matrix is free from incorporated insecticides.

28. A non living material according to claim 27, wherein the matrix has an initial, insecticide-free, solid state, where it contains at least one synergist, and wherein it has a final, solid state, where it contains an insecticidal coating.

29. A non living material according to any one of the claims 16-28, wherein the synergist is incorporated in the polymer matrix as part of a blend.

30. A non living material according to one of the claims 26-29, wherein the polymer of the matrix is a thermoplastic polymer.

31. A non living material according to claim 30, wherein the film comprises a film forming component reducing wash off and degradation of the insecticide from the netting or fabric by forming a water and optionally oil resistant film, the film being a molecular shield on or around the matrix integrating the insecticide in the film, wherein the film forming component comprises a polymeric backbone fixative and one or more components selected from paraffin oils or waxes, silicons, silicon oils or waxes, and polyfluorocarbons, or derivatives thereof.

32. A non living material according to claim 31, wherein the film forming component comprises a mixture of components selected from paraffin oils or waxes, silicons, and silicon oils or waxes, and polyfluorocarbon, or derivatives thereof.

33. A non living material according to claims 31 or 32, wherein the said film forming component comprises a mixture of a polyfluorocarbon and a paraffinic oil or a mixture of a polyfluoroalkyl and a polysiloxan.

34. A non living material according to any one of the claims 31-33, wherein the silicon oil or wax is a polysiloxan.

35. A non living material according to any one of the claims 31-34, wherein the polymeric backbone fixative is a resin, polyurethane or polyacryl.

36. A non living material according to any one of the claims 31-35, wherein the polyflurocarbon, paraffin oil or wax, silicon, silicon oil or wax, or derivatives thereof is/are attached to the polymeric backbone.

37. A non living material according to any one of the claims 26-36, wherein the insecticide is a pyrethroid.

38. . A non living material according to claim 37, wherein the insecticide is del- tamethrin.

39. A non living material according to any one of the claims 26-38, wherein the synergist is PBO.

40. A non living material according to any preceding of the claims 26-39, wherein the matrix is a fabric.

41. A non living material according to any preceding of the claims 26-40, wherein the matrix is a netting.

42. A non living material according to any preceding of the claims 26-40, wherein the matrix is a bednet.