TITLE: Insecticidal polyethylene fiber, yarn or textile products with improved migration profiles and washing resistance.

FIELD OF THE INVENTION

Present invention relates a method to manufacture a polyethylene fiber, yarn or products made from the polyethylene yarns comprising an active ingredient wherein the method comprises a step of heat treatment of the polyethylene fiber, yarn or products made from the polyethylene yarns in a temperature range from 80 °C to 130 °C. Such heat treatment is typically done for a selected time from between 10 to 120 seconds. By using the method of the present invention a textile product may be obtained comprising an active ingredient (e.g. insecticide) that has an improved migration rate of said active ingredient, e.g. to provide a bed net product that resist at least 20 washes and provides at least 80% mortality of the insects, such as mosquitoes. The present invention further relates to a product, such as polyethylene fiber, yarn or textile made from the yarn, obtainable by the method of the present invention.

BACKGROUND ART

Mosquito nets are often used where malaria or other insect-borne diseases are common, es- pecially as a tent-like covering over a bed. Mosquito net can be made from cotton, polyethylene, polyester, or nylon. A mesh size of 1.2 mm stops mosquitoes, and smaller, such as 0.6 mm, stops also other biting insects. Such bed nets are used to prevent malaria and today, WHO recommends the use of long impregnated bed nets (LLIN). Mosquito netting can be hung over beds, from the ceiling or a frame, built into tents, or installed in windows and doors. Mosquito nets treated with insecticides— known as insecticide treated nets (ITNs) or bed nets— were developed in the 1980s for malaria prevention. Newer, longer lasting insecticide nets (LLIN) now replace Insecticide-treated nets in many countries. ITN's are estimated to be twice as effective as untreated nets, and offer greater than 70% protection compared with no net. Earlier these nets were dip treated using a synthetic pyrethroid insecticide such as deltamethrin or Permethrin, which will double the protection over a non- treated net by killing and repelling mosquitoes. New technologies like used for Netprotect (polyethylene net), Olyset (polyethylene net) or Permanet (polyester net) allow for production of long-lasting insecticidal mosquito nets (LLINs), which release insecticide for approximately 3-5 years and do not need retreatment.

Such bed nets may be made of polyester fibers or polyethylene fibers. In the case of polyes- ter, mostly 100% polyester multi filament is used at denier 50, 75 or 100 with 36 filaments and mesh 156 (holes per square inch) and a specific weight (for example 0.39 kg). The polyester fibers are impregnated with insecticide, preferably a pyrethroid insecticide (such as deltamethrin or Permethrin).

Such polyester net is known as Permanet from the company Vestergaard Frandsen and developed by present inventor Ole Skovmand is described in WO0137662. Therein, is disclosed a curing method, passing net over a heated surface, such as an iron or a heat roller or heated with hot air . For netting as disclosed in WO/0137662, the temperature during the drying pro- cess must not exceed 80. The heat treatment is referred to curing that assures a good attachment of the coating additive to the yarn surface. The selected curing temperature is set to prevent degradation of the insecticide (deltamethrin), as the insecticide is temperature sensitive and to activate a cross linking process that results in coating. In the case of oleofin and other polymers with lower crystal temperature and extrusion temperature, the preferred technique is to incorporate insecticide or active ingredients in the material itself. The polymer composition comprising polyethylene allows for the incorporation of additives such as insecticide and other active ingredients and additives known as UV protector, flame protector, processing additives may be blended or mixed directly into the molten polyethylene composition, hereby incorporating into the polymer structure an insecticide. Alternatively, they are first integrated in more concentrated form in so-called Master Batches that then are melted together with the basic polymer in the final extrusion (Dow patent of 1975, BG1480125, and later GB 2276171 ). The insecticide is formulated into the polymer composition so that is it released in a controlled way, so-called controlled release. The skilled person then experiments with different ingredients and polymer composition to find the optimal release levels to obtain a yarn which can kill insects, e.g. mosquitoes according to WHO guidelines (reference 1 herein) or in general insects damaging crops in agricultural. In such application polyethylene yarns may be made into a textile structure and be used as a barrier to protect crops as described in EP141 1764B1 ("A Fence" Ole Skovmand et al).

Example of polyethylene with insecticide, prior art is JP8302080 (1996) discloses a resin composition comprising (A) 100 percent weight of a relatively low-migratory olefin polymer such as high-density polyethylene, medium-density polyethylene or polypropylene-based polymer, (B) 10-400 percent weight of a relatively high-migratory ethylene-based polymer such as low-density polyethylene, linear low-density polyethylene or ethylene copolymer, and (C) 0.3-15 percent weight of a pyrethroid-based insect-proofing agent such as terallethrin, pyrethrin, cyphenothrin, etholenprox or flulenprox.

This composition is capable of giving a molded form enabling the sustainability of its insect- proofing action to be controlled and having the sustainability of its insect-proofing action over a long period and also having high weatherability (controlled release).

For a bed net to be functional (protecting humans against the malaria mosquito), the insecti- cide is released on the surface of the fiber and the art is to control migration in the correct amount to achieve sufficient kill of mosquitoes and to make sure that the textile can be washed and after washing still releasing insecticide in a sufficient amount to kill mosquitoes.

WHO (World Health Organization) describes a WHOPES test protocol known to the skilled person, and is a scheme to get a bed net approved according to the WHO standards. Meeting the set standard is important to be accepted in the market. The standards and criteria for such release are typically tested in the WHO guidelines (reference 1 ; WHO: guidelines for laboratory and field testing of long lasting insecticidal mosquito nets; WHO/CDS WHOPES/GCD PP/2005 guidelines, herein further WHO-REF-1 ).

The method implied is a washing test under standard laboratory conditions. The principle of the washing test is that the active ingredient is gradually removed from the surface due to series of washing with defined intervals simulating use of the bed net over time. After each series of washing, the textile is tested using mosquitoes. Under such test at least 80% of the total tested mosquitoes must be killed (named mortality) after a 3 minutes exposure to the textile in test or 95 % must be knocked down (paralyzed). Having met either of these two criteria, such net passes the WHO minimum criteria and is then suitable for further field testing according to WHO (World Health Organization). Methods of making polyethylene fibers comprising active ingredients (thereof yarns and textile products such as bed nets), are described in WO20101 15709 (Ole Skovmand). Therein is disclosed a textile product comprising a polymer composition (e.g. polyethylene) and active ingredient (e.g. deltamethrin) and characterized by that the composition comprises polymer oil and/or a polymer wax. Yarns or fibers made from these compositions have release properties. Therein the inventor discloses a specific composition with controlled release properties.

Fabrics are conventionally produced by weaving, knitting or otherwise forming shrinkable fibers such as wool, silk, cotton, polyesters, acrylics and polyamides. After forming, the fabric is heated to a temperature below the melting point of the fiber to prevent that the yarn shrinks to its original form. Alternatively, the yarn itself is heat treated just after stretching to prevent the shrinkage; this process is called "relaxing". It may be carried out in a process that allows for some shrinkage during the relaxation or heat treatment to increase the stability of the final product (e.g.; 1 to 20 %). The shrinking relieves strains caused by the extrusion, followed by stretching, the forming (e.g. weaving) process, tightens the fabric, evens the bearing load of the fibers and may improves the feel of the fabric. If the heating is applied with the fabric under stress (or strain), either of a stretching or deforming (e.g. creasing) nature, the fabric will also set in the shape which it assumes under the stress (or strain).

In the art of making textiles there is often used the process step of heat setting. Heat setting is a technique used to set the textile meaning to fix the dimension. Tensions are built up in both yarns and finished textile products. The amount of shrinkage of polyethylene depends on the resin type, mold temperature; mold type, sheet orientation and effect of regrind resin.

Heat setting of synthetic fabrics eliminates the internal tensions within the fiber generated during manufacture and the new state can be fixed by rapid cooling. This heat setting fixes the fabrics in the relaxed state and thus avoids subsequent shrinkage or creasing of fabric. Pre- setting of goods make it possible to use higher temperature for setting without considering the sublimation properties of dyes and also has a favorable effect on dyeing behavior and running properties of goods. On the other hand, post setting can be combined with some other operations such as thermosol dyeing or optical brightening of polyester, post setting as a final finish is useful to get a high dimensional stability along with desired handle.

The application of heat in heat setting can be done by hot air, on a pin Stenter at 220° C for 20-30 seconds for polyester goods and at a lower temperature range of 190-225° C for 15 -20 seconds for polyamides . Acrylics may be heat set partially at 170-190 °C for 15-60 seconds to reduce formation of running creases but higher temperature should be avoided to prevent yellowing.

US4897902 discloses a method for preparing fabrics comprises the steps (a) forming a fabric from stretched fibers of tenacity at least about 20 g/denier and tensile modulus at least about 600 g/denier containing polyethylene of weight average molecular weight at least about 500,000, and (b) heating the fabric at a temperature between about 120 ⁰ C and about

155 °C sufficient and for a time sufficient for the fibers to shrink between about 1 % and about 10% of their length in the fabric formed in step (a).

US4897902 also includes a method of preparing heat-set fabrics which comprises the steps: (a) forming a fabric from stretched fibers of tenacity at least about 20 g/denier and tensile modulus at least about 600 g/denier containing polyethylene of weight average molecular weight at least about 500,000, and (b) heating the fabric under an applied stress (or strain) at a temperature between about 120 ⁰ C and about 155 °C sufficient and for a time sufficient to set the fabric in a shape assumed under the applied stress (or strain). The applied stress may be simple tension, a deformation such as a crease or a combination of tension and deformation. Alternatively, the fabric can be held to fixed dimensions and the stress caused by shrinkage. US478633 relates to a method of reducing a high strength fiber and to a high strength polyethylene fiber so produced. Therein is disclosed a method of treating a fiber of polymeric material which comprises the steps of: (a) cross linking the polymeric material; (b) heating the fiber to a temperature, T1 , which (i) in the event the polymer is amorphous, is above the glass transition temperature, Tg, of the polymer and, (ii) in the event the polymer is crystalline, is above the second order transition temperature, Tac, and below the crystalline melting temperature, Tm, of the polymer; (c) drawing the fiber to a draw ratio of at least about two at a rate of at least about 200% per minute; and (d) cooling the fiber.

After the polymeric material of the fiber is crosslinked, the fiber is drawn at elevated tempera- ture. The temperature, T1 , at which the fiber is drawn, depends on the particular polymeric material. If the polymeric material is amorphous, the drawing temperature, T1 , should be above the glass transition temperature, Tg, of the polymer. For amorphous polymers, the drawing temperature T1 can be any temperature above Tg at which the polymer is self- supporting and capable of being processed. Generally, the drawing temperature, T1 , will be lower than the conventional extrusion temperature used for that polymer.

For crystalline polymers the drawing temperature, T1 , should be above the second order transition temperature, T ac and below the crystalline total melting temperature, Tm, of the polymer. T.ac is a pre-melting transition temperature at which semi crystalline polymers show a mechanical loss peak, as measured by mechanical spectroscopy. At this temperature hindered rotation of the polymer chains inside the polymer crystals can occur. In the case of polyethylene, the drawing temperature should be between about 80° C to about 130°C according to US478633. US478633 does is not disclosed active ingredients as for example an insecticide incorporated in the polyethylene. There is not disclosed a specific time interval as fibers are "drawn" as at least 200 % per minute, to a ratio of at least two its initial length.

After drawing the fiber it is cooled to ambient temperature. Cooling is generally effected by air cooling. The fiber can however be run through a bath of cold water if more rapid cooling is desired.

There is also heat treatment done by the same method by for example hot air also using for example a Stenter. However, the achieved effect is very different. Such heat treatment is done for example in the process to make composite yarns; contacting the yarn with hot air for an exposure time on the order of about 0.1 second. In summary, prior art discussed herein do not teach or mentioned controlled migration using polyethylene which comprises active ingredients (deltamethrin) to make textile products such as bed nets to be used as prevention tools against malaria. Further, there is no teaching on how to control migration of active ingredients (such as insecticides) from polyethylene compositions, yarns or fibers or there from made textile products.

There are two known methods to regulate migration of active ingredients from yarns or textile products (e.g. a polyethylene composition comprising an insecticide made into a textile prod- uct) which are available to the skilled person at present.

The first method is by using additives such as Chimasorb, Tinuvin or Irganox further listed herein. The skilled person defines by experimentation which is the optimal migration level to be obtained to achieve mortality level of at least 80% mortality after at least 20 washes under laboratory conditions as tested and measured according to the protocol described in WHO REF-1. Such compositions and the use of suitable additives are for example described in WO03063587 (page 14).

The second method to regulate migration known to the skilled person is by making use of polyethylene compositions and the addition of oils and waxes as described in detail in WO20101 15709 (Ole Skovmand).

These two methods are suitable to obtain a textile product comprising an active ingredient and suitable to be approved by the WHO in case of a bed net (LLIN) for the prevention of malaria infections and to obtain at least 80% mortality after at least 20 washes under laboratory conditions as tested and measured according to the protocol described in WHO REF-1.

The problem with the two methods described above, is that the active ingredient migrates as well as the added additives. The additive such as C81 as defined herein, migrates out of the polyethylene composition in the time. As time passes, there will be less and less additive available in the polymer composition, which in the end influences the migration of active ingredient (less available).

Olefin yarn may be created through a melt spinning process. Once the polymer is made, it is melted and pumped at high pressure into a spinneret which causes it to form streams of the polymer. The melted product is usually filtered before entering the spinneret to prevent lumping of the polymer which could cause clogging and disruption of the spinning process. Most synthetic and cellulosic manufactured fibers are created by "extrusion"— forcing a thick, viscous liquid through the tiny holes of a device called a spinneret to form continuous filaments of semi-solid polymer. In their initial state, the fiber-forming polymers are solids and therefore must be first converted into a fluid state for extrusion. This is usually achieved by melting, if the polymers are thermoplastic synthetics (i.e., they soften and melt when heated). If they cannot be dissolved or melted directly, they must be chemically treated to form soluble or thermoplastic derivatives.

A general description of melt spinning process of polyethylene is described in

WO2010015256. Therein is also referred to the extrusion temperature (page 8, 9 and 13). The polymer matrix is melted at a certain temperature and thereafter extruded under a certain temperature.

US201 10256198 also describes the known production method of polypropylene filaments, fibers, threads and yarns, insecticidal containing polymeric material is melted, formed into spun threads and cooled, the spun threads obtained are led through a drawing system and draw and then optionally the setting of the filaments, fibers, threads and yarns takes place. As described in US201 10256198, the melt spinning process comprises the steps of; preparing the spinning melt, melt spin, cooling, spin finishing, drawing and after treating.

WO2008032844 describes a method to manufacture a polyethylene fiber or products made from the polyethylene fibres comprising an active ingredient. For example, on page 12, is disclosed the temperature of extruding (at a cylinder temperature of 130°C to 210°C). On page 1 1 under example 1 , there is disclosed a melting kneading zone temperature of 200°C and a die temperature of 200°C. Such selected temperatures are standard in the manufacturing of polyethylene fibers.

EP2216430 discloses in paragraph 12 and 13 discloses the spinning temperature within a range of 200°C to 300° C and a heat stretching temperature is 130°C to 160°C and heat set- ting is 70°C to 100°C. Heat setting is also a standard operation for the manufacturing of polyethylene fibers.

There is a continuous need to improve polyethylene yarns and textile products made thereof with specific improved migration properties of active ingredients in order to effectively protect humans against insects and diseases transmitted from insects (such as the malaria disease).

SUMMARY OF THE INVENTION

The present invention relates to a method to manufacture a polyethylene fiber, yarn or products made from the polyethylene yarns comprising an active ingredient (e.g. an insecticide). The present invention also relates to a polyethylene fiber, yarn or products made from the polyethylene yarns, in particular textile products. Such textile products are known as long lasting impregnated bed nets (World Health Organisation).

The problem to be solved in present invention is effectively (in a more stable way) to regulate the migration of active ingredients (e.g. insecticides) from a yarn (e.g. polyethylene) or a textile product made form such yarn obtaining improved migration of active ingredient available on the surface of the yarn or a textile product.

Present invention discloses herein a novel alternative method which may be used to regulate the migration of active ingredients.

The solution as found by the present inventor was identified during optimization of the heat setting temperature, and it was discovered that the herein described process with the new particular steps of heat treatment at particular exposure times, influenced the migration of insecticide and that the heat treatment could be optimized to provide a net product with improved insecticidal activity in a wash-and-bioassay tested series up to 20 washes without losing extra insecticide in the wash exposure. This solution results in a more stable and more controlled migration of the active ingredient to the surface of the yarn or textile product made thereof.

Below is a detailed description of the invention. There are 3 preferred ways of using the heat treatment step according to present invention.

1 ) Yarn is heat treated

The first method now available due to present invention is to heat treat a yarn. Yarns are made according to the known process steps available to the skilled person and there is ap- plied a heat treatment of the present invention; at a temperature between from 80°C to 130°C applied for duration of 10 to 120 seconds.

An preferred embodiment is a method according to the first aspect a yarn is heat treated at a temperature between from 80°C to 130°C applied for duration of 15 to 80 seconds.

A preferred embodiment is yarn heat treated and a textile product is knitted obtaining a textile product according to present invention with migration properties as described herein due to the heat treatment. 2) . Yarn produced using a heat setting step and thereafter the textile is made and heat treated. The second possibility, a yarn may be heat set with standard method. Yarns are produced and stored until needed for knitting or weaving. Heats set yarns are relaxed by the standard heat setting procedure.

Such heat set yarn may be made into a textile product such as a bed net, and thereafter a heat treatment at a temperature between from 80°C to 130°C applied for duration of 10 to 120 seconds is given to the final textile product obtaining improved release properties of present invention.

An embodiment is a yarn produced and not heat set and thereafter the textile product is heat set AND heat treated at a temperature between from 80°C to 130°C applied for duration of 15 to 80 seconds as with steps of present invention. Such textile product has the migration properties as disclosed herein due to the heat treatment.

3) Yarn is produced and not heat set and thereafter the textile product is heat set AND heat treated at a temperature between from 80°C to 130°C applied for duration of 10 to 120 seconds as with steps of present invention. Such yarns may be stored until needed to make into a textile product by knitting or weaving.

This third possibility comprises first to produce a non heat set yarn (not relaxed yarn) as produced with standard methods, thereafter knitted or woven into a textile product which is then first heat set using standard methods AND thereafter heat treat the textile product at a temperature between from 80°C to 130°C applied for duration of 10 to 120 seconds.

By using such method combination of first heat setting thereafter heat treatment, the textile product as described also has the improved migration properties.

Accordingly a first aspect of the present invention is a method to manufacture a polyethylene fiber or products made from the polyethylene fibres (e.g. yarns and/or textiles) comprising an active ingredient wherein the method comprises a step of heat treatment of the polyethylene yarn or products made from the polyethylene yarns in a temperature range from 80 °C to 130 °C applied for a sufficient time.

In one embodiment the polyethylene fiber or products made from the polyethylene fibres is selected from a polyethylene fiber.

In another embodiment the polyethylene fiber or products made from the polyethylene fibres is selected from a yarn made from polyethylene fibres. In a further embodiment the polyethylene fiber or products made from the polyethylene fibres is selected from a textile product made from polyethylene yarns. Criteria for "efficacy" according to WHO test protocol (WHO REF 1 , page 7 chapter 2.2 under "Efficacy'")

A LLIN (long lasting impregnated Net) approved by WHO must comply with the defined "biological efficacy criterion which is as follows; nets washed at least 20 times that cause greater or egual to 80% mortality and/or greater than or egual to 95% KD (knock-down) meet the cri- teria to undergo phase II testing. Phase two testing is a small scale field trial studying the efficacy of the net in experimental huts using susceptible, free-flying, wild mosguitoes.

Textile products prepared according to the first aspect of present invention provide an insect, e.g. mosguito mortality of at least 80%, more preferred 90% and most preferred 99 to 100% after 20 washes.

Without being limited to the theory, it may in theory be possible not to work with a upper limit of duration of the heat treatment but in practice, as the factory operates on unit production it is herein understood that such duration is as short as possible to be economically viable step in the production of textile products.

Accordingly, present invention is a method according to first aspect, wherein a polyethylene fiber or products made from the polyethylene fibres are pre- treated under standard heat setting conditions and thereafter followed by a heat treatment.

An embodiment is a method, wherein a polyethylene fiber or products made from the polyethylene fibres are pre- treated under standard heat setting conditions and thereafter followed by a heat treatment at a temperature of 150°C, more preferred 140 °C and most preferred 130 °C. Depending on the chosen temperature, the skilled person needs to experiment with the optimal time of heat application. The chosen time, may be in case of a heat treatment temperature of 150 °C depending on the type of product (for instance the polymer composition and type of additives) used and also which type of active ingredient is chosen, and may be extremely short time as for example 5 to 10 seconds.

Polyethylene (depending on the type of PE), has a melting point of 120 to 130°C and the in- secticide deltamethrin is melting at 100°C-102 °C. For different types of insecticides, there will be specific heat treatment temperatures.

Such chosen time selected by experimentation, is denoted herein the term "sufficient time". A preferred embodiment a method to manufacture a polyethylene fiber or products made from the polyethylene fibres comprising deltamethrin wherein the method comprises a step of heat treatment of the polyethylene fibres, yarns or products made from the polyethylene yarns in a temperature range from 80 °C to 130 °C and the heat treatment is done for a selected time from between 10 to 120 seconds.

The skilled person can now easily determine what the optimum temperature and time is with the given variables to obtain optimal migration according to the present invention. Method of applying heat - heat treatment

Heat treatment may be applied directly at chosen interval as disclosed herein or by applying heat gradually increasing in temperature within the herein disclosed time interval. In both cases, improved migration was observed. An improved migration effect of the insecticide is found when heat treatment is done at a chosen constant temperature of at least 80°C and not higher than 130°C.

An improved migration effect of the insecticide is found when heat treatment is done at a chosen constant temperature. Thus in a further embodiment the heat treatment is done at a con- stant temperature selected between 80°C and 130°C, such as a constant temperature of between 80°C and 90°C, between 90°C and 100°C, between 100°C and 1 10°C, between 1 10°C and 120°C, or between 120°C and 130°C.

Gradual heat treatment is applying heat from 80 °C to 130 °C for a selected time applied heat from between 10 to 120 seconds, i.e. slowly increasing the temperature within the time interval (10 to 120 seconds). This heat treatment as shown herein is very effective way of obtaining a textile product of the present invention.

Constant heat treatment is another way of obtaining a textile product of the present invention. Constant is denoted herein a choosing a fixed temperature of heat treatment, for example

90°C for 15 seconds but keeping the temperature constant for a chosen amount of time within the time interval as disclosed herein.

Present inventor also found out that by gradually increasing the temperature from at least 80°C to not higher than 130°C the improved controlled migration is also obtained and high amount of washing resistance is found without compromising shrinking and loss of net material due to breaking, if the process according to present invention includes a stretching step. If the process according present invention does not include a stretching because yarns are already relaxed, the process according to present invention may include a nearly constant temperature at preferred 1 10° C to 120°C for duration of 15 to 120 seconds, more preferred for duration of 25 to 60 seconds.

An embodiment is a relaxed yarn heat treated a constant temperature at 1 10° C to 120°C for duration of 15 to 120 seconds.

An embodiment is a relaxed yarn heat treated at constant temperature at 1 10° C to 120°C for duration of 25 to 60 seconds.

The present inventor has used this WHO REF 1 test protocol to be able to further develop and improve and identify new polyethylene fibres, yarns and textile products. An improved textile product is a product which can resist at least 20 washes (more preferred more than 20 washes) and when tested in the bio-assay according to WHO REF1 has very high mortality (at least 80%), more preferred 90%, and most preferred more than 95% mortality. In case the method according to present invention is to be used for the manufacturing of bed net according to WHO specifications, then WHO REF 1 is used. In the case, as for example cloths are manufactured from the yarns as made by the method of present invention, such washing test is may be not a requirement. The active ingredient migrates according to present invention, which is a suitable product for the either killing insects or protecting human from infections transmitted by insects. In other words, the WHO REF 1 test is mostly preferred for bed nets protecting people against malaria infections as transmitted by mosquitoes.

It is believed that the heat treatment altered the polyethylene structure in such a way that migration of active ingredients is improved. Heat treatment changes the nature of polymer in a way that migration of active ingredients is better controlled in a unique way.

From the data disclosed herein, it can be concluded that the herein defined heat treatment at a temperature of between 80°C and 130°C applied for a short and specific time, herein from about 10 seconds to 120 seconds, results in such a changed polyethylene structure which surprisingly improves wash ability (i.e. durability) and obtain a high mortality after each wash.

Such short heat treatments can be controlled accurately in the factory within +/- 2°C once the temperatures of sequential arranged ovens of the stentors are stabilized. The obtained improved washing resistance (20 washes) as exemplified herein, demonstrates that the migra- tion of active ingredient is well controlled and regularly and enough to obtain high killing rates of at least 80% mortality

It is herein proposed without being limited to the theory, that the migration of active ingredient (dosage of insecticide on the surface of the fibre) follows the general equation:

Dose effect (e.g. migrated insecticide) =k x [T-T°] x time, wherein T is applied heat treatment temperature, T° is the temperature of the fiber or yarn at time 0 (zero) and time is the time (seconds) applied heat set temperature (for example 1 10°C for 30 seconds or 120°C for 20 seconds) and k is a factor to be determined experimentally and depends on the polymer composition, additives and physical parameters such as yarn diameter.

As the molten polymer composition has a certain start temperature entering the extruder, T° can vary. Typically T° is for example monitored at approximately 90°C.

In summary, the migration of active ingredient obtained by heat treatment depends on a specific interval of chosen heat set temperature for a specific time. In this specific interval of chosen heat set temperature and time applied, the polyethylene polymer or composition of polyethylene and additives change in a special way so that migration of active ingredients is better (more stable) and regulated.

It is believed herein that this migration mechanism and the effect of migration due to heat treatment, is a general principle, and may be applied for in general active ingredients as listed herein also and present in polyethylene compositions. For example, a bactericide or a syner- gist (PBO) would follow such migration depending on the heat treatment chosen temperature and duration of the heat treatment.

A second aspect of present invention is a polyethylene fibre, polyethylene yarn or polyethylene textile product obtainable by the method of the present invention.

DEFINITIONS

"Additives" denotes ingredients known to the skilled person and are added to in general olefins for the stabilization against factors, such as UV, oxidation, influence of pesticides, radicals formation and blocking these radicals as these can destroy polyethylene's films for examples.

Herein is a list proved of additives known to the skilled person and are used herein as to make release or migration compositions important for textile product killing insects. WO2003063587 and WO20101 15709 are used as a reference herein listing additives. "Heat setting" denotes subjecting a fiber (in fabric or yarn form) to a temperature-stress history to fix the fiber in a particular configuration. The term "heat-shrinking" is intended to mean a form of heat-setting in which little or no external stress or strain is applied to the fiber during heating. Other forms of heat setting include heating under deforming stress, heating while stretching and heating while restrained such that stress develops.

"Curing" denotes a process following addition of a finish to textile fabrics in which appropriate conditions are used to effect a chemical reaction (e.g. polymerisation). Heat treatment for several minutes has been standard, But higher temperatures for short times (flash-curing) and long times at low temperatures and higher regain (moist Curing) are also used.

"Dose effect" is the effective dose on the surface of the fiber or yarn, sufficient to kill at least 80% of mosquitoes after washing according to REF 1 of WHO protocol. Such dose effect is therefore related to the term controlled release or migration, as sufficient amount if released to kill at least 80% mosquito's and at the same time, and obviously not all the active ingredient migrates out of the compositions (named depletion) at once (this would imply obtaining very low wash resistance as for example 2-3 times and after 5 the mortality would be far below 80% (for example 40% or lower). This would mean that such obtain product would be not suitable as long lasting malaria bed net according to the approval schedule of Who and thus such product would not be of commercial interest.

"Drying" is typically performed at lower temperature than curing, since drying does not as such directly relate to that conditions are used (e.g. heating) to effect a chemical reaction (e.g. polymerisation). Drying may be performed for a number of reasons, e.g. to remove excess of solvent.

"Fabric" denotes a flexible artificial material made up of a network of natural or artificial fibres (thread or yarn) formed by e.g. weaving, knitting or pressed into felt. An example of a fabric is a cloth, a net (e.g. a mosquito net), a tent etc.

"Fiber" denotes elongated stringy natural, man-made or manufactured material. Natural vegetable fibers, generally consist of cellulose, examples include cotton, linen, and hemp. Natural animal fibers include spider silk, sinew, hair, and wool. Man-made fibres are those that are made artificially, but from natural raw materials (often cellulosic). Examples include fiberglass, rayon, acetate, cupro and the more recently developed Lyocell. Synthetic fibers include nylon, acrylic, polyester, polyethylene and graphite fiber. Fibers as used in the present invention comprises polyethylene. "Masterbatch" is denoted herein as a concentrated pre-mixture of one or more additives in a polyethylene composition.

"Incorporation" is denoted herein as an active ingredient which is present in the polyethylene composition and gradually migrates out to the surface. The active ingredient is mixed in the molten polyethylene composition, where from yarns and textile products are made.

"Insecticide" denotes a chemical substance (active ingredient) used to kill insects or an acaricide. "Repellent" denotes an active ingredient in a textile product that has the ability to repel insects such as e.g. fleas and ticks. A repellent is not as such capable of killing an insect.

"Textile" denotes any kind of woven, knitted, knotted, tufted or non-woven fabric. Textile also refers to the yarns, threads that can be spun, woven, tufted, tied and otherwise used to e.g. manufacture a fabric.

"WHO test" is a standard test for washing net samples. However, this established standard wash test may be used for washing a textile or net of interest in general in accordance with requirements as described herein.

"Washing resistance" is a term well known to the skilled person and the method of washing bed nets samples and thereafter testing for mortality on mosquitoes is as well described in WHO REF-1. The obtain value of number washes - i.e. a textile sample (polyethylene composition) which is washed for example 10 times and after washing tested for mortality in bio- assay and which passes the criteria of mortality of 80% is a measurement for the life span of such textile product. It is an indication, that such textile product has a life span of about 4 years to 7 years and having a high efficacy during at least 4 years in protecting humans against malaria. Herein is included thus that the textile product will be washed by the consumer, hang up for drying under proper instructed conditions by the manufacturer of such bed nets and that the net of course are regularly inspected for holes. It is therefore that WHO has adapted this protocol for net producers to pass the washing test criteria of 10 or more washes (20 washes as the "pass criteria") as a part of the WHOPES bed net approval procedure. Such products passing the WHOPES test obtain the status of a long lasting impregnated bed net (LLIN):

"KD" herein denotes knock down of mosquitoes in test WHO REF 1 herein. Knock-down of 95% means that 95% of the tested mosquito population in the cone tests (WHO REF 1 ) is knocked-down after 60 minutes (also KD ₆₀ ). Mosquitoes were considered knocked down or dead if they cannot fly and cannot stand upright on either the side or the bottom of the paper cups as described in the WHO REF 1 test protocol.

DRAWINGS FIG 1 : shows that increasing the temperature from 80° C to 120°C results better washing resistance (i.e. a better net product with improved migration properties and giving humans a better protection against malaria). Figure 1 shows that 120°C is more suitable and preferred heat treatment as compared to temperature of 80°C. FIG 2: (X- axis "amount of washes"- versus Y-axis "amount of deltamethrin in the yarns") shows that the release (migration) of active ingredient is well controlled and that there is not an immediate release of the total amount of insecticide and also shows that very high number of washes can be reached due to the heat treatment (> 15 washes and reaching the at least 80% mortality according WHO REF 1 protocol.

DETAILED DESCRIPTION OF THE INVENTION

A fiber, a yarn and Textile product

A fiber comprising an active ingredient is produced according to standard methods. Fibers are made into a yarn.

A polyethylene yarn is produced by the standard methods.

An example of a relevant textile product is a film, a net, a sheet, a tarpaulin or a cloth.

Preferably, the textile product is a net comprising an effective amount of insecticide and more preferably wherein the insecticide net is a mosquito net to protect humans against malaria infections transmitted by malaria mosquitoes. Textile bed nets are typically woven or knitted according to known processes.

The textile products may be made of yarns comprising colors such as blue, red or black which are made according to present invention.

The textile product (e.g. bed net) as known to the skilled person may be constructed of differ- ent parts, meaning, the side of one insecticide (deltamethrin) and the roof of another for example a carbamate insecticide. This is a well known technique to increase the efficacy of bed nets against insecticide resistant mosquito strains. Yarns of such combination net's, may be made according to the present invention and present polyethylene compositions. Also, combinations of a non-pyrethroid and a repellent can be used with present invention. For example a polyethylene yarn comprises the composition of present invention, the composition comprising a carbamate and is heat treated according to the method described herein and is combined with a yarn comprising a repellent (e.g. DEET).

Textile products may be tarpaulin, a sheet, a film, a net, combined tarpaulin with net, eave net, curtains, bed nets, cloths to wear or any shaped form suitable for the protection against nuisance insects. Most preferred textile product is a bed net.

An active ingredient

Suitable active ingredients are selected but not limited to from the group of pyrethroids, or- ganophosphates and carbamates and pyrrols. The skilled person can select suitable active ingredients from the list provided below.

Ideally, one active ingredient or repellent has some repellent or contact-irritancy effect or a fast knock down effect, thus to provide personal protection (in practice this is generally pyrethroids, carbamates and repellents). The other active ingredient can be insecticide, an insect repellent, a fungicide, and acaricide or a bacteriostatic. In case an acaricide is chosen, such textile products are then effective against ticks and agriculture important pests.

As examples of the first, one insecticide is a pyrethroid like deltamethrin and the other is pirimiphos methyl, in case the insecticide resistance mechanism is Kdr. In another example, the first insecticide is a pyrethroid and the bacteriostatic is a silver salt. In another example, the first insecticide is a pyrethroid and the second is a pyrrol like chlor- fenapyr.

In a third example, the first insecticide is permethrin and the second biocide is a synergist like piperonyl butoxide.

Also, it may be one insecticide or biocide all depending on the product and application. The insecticide works by contact, not only by oral ingestion. It may work as a fast paralyzing insecticide or as a slow acting killing insecticide or as sterilizing agent. The insecticide may pos- sess repellent or deterrent activity and this may be the main principle. It must have low mammalian toxicity. Suitable insecticides are known by persons skilled in the art. They may be the active ingredients listed below, or belong to the same or other groups. Especially, some insecticides and repellents are used as synergistic or at synergistic dosages and can be used in blends. Some herbicides have been shown to have synergistic effect to insecticides where mixed function of oxidases is the known resistance mechanism.

Preferred insecticides may belong to the group pyrethroid compounds such as ethofenprox: 2- (4-ethoxyphenyl)-2-methylpropyl-3-phenoxybenzyl ether; Fenvalerate: (RS)-alpha-cyano-3- phenoxybenzyl (RS)-2-(4-chlorophenyl)-3 methylbutyrate; Esfenvalerate:(S)-alpha-cyano-3- phenoxybenzyl (S)-2-(4-chlorophenyl)-3-methylbutyrate; Fenpropathrin: (RS)-alpha-cyano-3- phenoxybenzyl 2,2,3,3-tetramethylcyclopropanecarboxylate; Cypermethrin: (RS)-alpha-cyano- 3-phenoxybenzyl (1 RS)-cis, trans-3-(2,2-dichlorovinyl)-2,2- dimethylcyclopropanecarboxylate; Permethrin: 3-phenoxybenzyl (1 RS)-cis,trans-3-(2,2-dichlorovinyl)-2,2- dimethylcyclopro- pane- carboxylate; Cyhalothrin: (RS)-alpha-cyano-3-phenoxybenzyl (Z)-(l RS)-cis-3- (2- chloro-3,3,3- trifluoroprop-1-enyl)-2,2-dimethylcyclopro panecarboxylate; Deltamethrin: (S)- alpha-cyano-3- phenoxybenzyl (1 R)-cis-3-(2,2-dibromovinyl) -2,2- dimethylcyclopropanecarboxylate; Cyclo- prothrin: (RS)-alpha-cyano-3-phenoxybenzyl (RS)- 2,2-dichloro -1-(4-ethoxyphenyl)- cyclopropanecarboxylate; Fluvalinate (alpha-cyano-3- phenoxybenzyl N-(2-chloro- alpha, alpha,alpha-trifluoro-p-tolyl) -D-valinate); Bifenthrin: (2- methylbiphenyl-3-ylmethyl)0(Z)- (1 RS)-cis-3-(2-chloro-3,3,3-trifluoro-1-propenyl) -2,2- dimethylcyclopropanecarboxylate; 2- methyl-2-(4-bromodifluoromethoxyphenyl) propyl (3- phenoxybenzyl) ether; Tralomethrin: (S)- alpha-cyano-3-phenoxybenzyl (1 R-cis)3((1 'RS)(I ',2',2',2'-tetrabromoethyl)) -2,2- dimethylcyclopropanecarboxylate; Silafluofen: 4-ethoxyphenyl (3-(4-fluoro-3- phenoxyphenyl)propyl}dimethylsilane; D-fenothrin: 3-phenoxybenzyl (1 R)-cis, trans)- chrysanthemate; Cyphenothrin: (RS)-alpha-cyano-3-phenoxybenzyl (1 R-cis, trans)- chrysanthemate, D-resmethrin: 5-benzyl-3-furylmethyl (1 R-cis, trans)-chrysanthemate; Acri- nathrin: (S)-alpha-cyano-3-phenoxybenzyl (1 R-cis(Z))-(2,2-dimethyl-3- (oxo-3-(1 , 1 ,1 , 3,3,3- hexafluoropropyloxy)propenyl (cyclopropanecarboxylate; Cyfluthrin: (RS)-alpha-cyano-4- fluoro-3-phenoxybenzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate; Tefluthrin:

2,3,5,6-tetrafluoro-4-methylbenzyl (1 RS-cis (Z))-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2- dimethylcyclopropanecarbo xylate; Transfluthrin: 2,3,5,6-tetrafluorobenzyl (1 R-trans)-3-(2,2- dichlorovinyl) -2,2-dimethylcyclopropane-carboxylate; Tetramethrin: 3,4,5,6- tetrahy- drophthalimido-methyl (1 RS)-cis, trans-chrysanthemate; Allethrin: (RS)-3-allyl-2- methyl-4- oxocyclopent-2-enyl (1 RS)-cis, trans-chrysanthemate; Prallethrin: (S)-2-methyl-4- oxo-3-(2- propynyl)cyclopent-2-enyl (1 R)-cis, trans-chrysanthemate; Empenthrin: (RS)-I- ethynyl-2- methyl-2-pentenyl (1 R)-cis,trans-chrysanthemate; Imiprothrin: 2,5-dioxo-3-(prop-2- ynyl)imidazolidin-1-ylmethyl (1 R)-cis; trans-2,2-dimethyl-3-(2-methyl-1-propenyl)- cyclopropanecarboxylate; D-flamethrin: 5-(2-propynyl)-furfuryl (1 R)-cis, trans- chrysanthemate, or 5-(2-propynyl)furfuryl 2,2,3,3-tetramethylcyclopropane-carboxylate.

Therefore, in a preferred embodiment, one filament can comprise a pyrethroid (such as e.g. deltamethrin, permethrin or bifenthrin), and the other filament a piperonyl butoxide. These can be incorporated into filaments and thereafter spun into yarns. Insects are capable of developing resistance, and mosquitoes and other biting insects have already been observed to develop resistance to pyrethroids. In such cases, it may be advantageous to replace the pyrethroid with another insecticide with a low mammalian toxicity or to impregnate a part of the material net with a pyrethroid and a part of it with another insecticide. Such a combination may also be used in general as a strategy to delay resistance development. Care should be taken to combine insecticides that have little or no chance to develop cross resistance, e.g. where the development of resistance to one of them also confer resistance to the other even the two insecticides are of different type. Such alternative or supplemental insecticides may be compounds such as organophosphorous compounds organo- phosphorous compounds such as: Fenitrothion: 0,0-dimethyl 0-(4-nitro-m-tolyl) phosphoro- thioate; Diazinon: 0,0-diethyl-0-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphorothioate; Pyrida- phenthion: 0-(1 ,6-dihydro-6-oxo-1-phenylpyrazidin-3-yl) 0,0-diethyl phosphorothioate,; Pirimi- phos-Etyl: 0,0-diethyl 0-(2-(diethylamino) 6-methyl-pyrimidinyl) phosphorothioate; Pirimiphos- Methyl: 0-[2-(diethylamino)-6-methyl-4pyrimidinyl] 0,0-dimethyl phosphorothioate; Etrimphos: 0-6-ethoxy-2-ethyl-pyrimidin-4-yl-0,0-dimethyl-phosphorothio ate, Fenthion: 0,0-dimethyl-0-[-3- methyl-4-(methylthio) phenyl phosphorothioate, Phoxim: 2-(diethoxyphosphinothoyloxyimino)- 2-phenylacetonitrile; Chlorpyrifos: 0,0-diethyl-0-(3,5,6-trichloro-2-pyrinyl) phosphorothioate; Chlorpyriphos-methyl: 0,0-dimethyl 0-(3,5,6-trichloro-2-pyridinyl) phosphorothioate; Cyano- phos: 0,0-dimethyl 0-(4cyanophenyl) phosphorothioate; Pyraclofos: (R,S)[4-chlorophenyl)- pyrazol-4-yl] -O-ethyl-S-n-propyl phosphorothioate; Acephate: 0,S-dimethyl acetylphospho- roamidothioate; Azamethiphos: S-(6-chloro-2,3-dihydro-oxo-1 ,3-oxazolo [4,5-b] pyridin-3- ylmethyl phosphorothioate; Malathion: 0,0-dimethyl phosphorodithioate ester of diethyl mer- captosuccinate; Temephos: (0,0'(thiodi-4-1-phenylene) 0,0,0,0-tetramethyl phosphorodithioate, Dimethoate: ((0,0-dimethyl S-(n-methylcarbamoylmethyl) phosphorodithioate, Formo- thion: S[2-formylmethylamino]-2-oxoethyl]-0,0-dimethyl phosphorodithioate; Phenthoate: 0,0- dimethyl S-(alpha-ethoxycarbonylbenzyl)-phosphorodithioate.

Furthermore, carbamate compounds may be applied including compounds such as: Alany- carb: S-methyl-N[[N-methyl-N-[N-benzyl-N(2-ethoxy-carbonylethyl) amino- thio]carbamoyl]thioacetimidate; Bendiocarb: 2,2-dimethyl-1 ,3-benzodioxol-4yl- methylcarba- mate); Carbaryl (1-naphthyl N-methylcarbamate); Isoprocarb: 2-(1-methylethyl) phenyl methylcarbamate; Carbosulfan: 2,3 dihydro-2,2-dimethyl-7-benzofuranyl [(dibutylamino)thio] methylcarbamate; Fenoxycarb: Ethyl[2-(4-phenoxyphenoxy)ethyl] carbamate; Indoxacarb: Me- thyl-7-chloro-2,3,4a,5-tetrahydro-2-[methoxycarbonyl (-4-trifluoromethoxyphenyl)]; Propoxur: 2-isopropyloxyphenol methylcarbamate; Pirimicarb: 2-dimethylannino-5,6-dinnethyl-4- pyrimidinyl- dimethylcarbamate; Thidiocarb: Dimethyl N,N'(thiobis((methylimino)carbonoyloxy) bisethanimidiothioate); Methomyl: S-methyl N-((methylcarbamoyl)oxy)thioacetamidate; Ethio- fencarb: 2-((ethylthio)methyl)phenyl methylcarbamate; Fenothiocarb: S-(4-phenoxybutyl)-N,N- dimethyl thiocarbamate; Cartap: S,S'-(2- 5dimethylamino)trimethylene)bis (thiocar- bamate)hydrochloride; Fenobucarb: 2-sec- butylphenylmethyl carbamate; XMC: 3,5- dimethylphenyl-methyl carbamate; Xylylcarb: 3,4- dimethylphenylmethylcarbamate.

Newer insecticides with lower mammalian toxicity at use dosage are interesting alternatives, especially because vector insects rarely have developed resistance to these. Such new groups of insecticides are pyramidialmines (Pyrimidifen), Pyrazoles (Fipronil and Fenpyrox- iamte), Pyrrols (clorfenapyr), dicloproamid. Chlorphenapyr is especially interesting since it has been used experimentally (Rowland et al, 2005) and shown interesting, though slow effect. Where nets and other impregnated materials are used in mass campaigns, the alternative or supplemental insecticide may also be an insecticide with a sterilizing effect thus to sterilize the mosquitoes and avoid the next generation of mosquitoes. Such insecticides can be of the benzoyl urea group such as 1-(alfa-4-(chloro-alpha-cyclopropylbenzylidenamino-oxy)-p-to lyl)- 3-(2,6-diflourobenzoyl)urea, Diflubenzuron: N-(((3,5-dichloro-4-(1 , 1 ,2,2- tetraflouroeth- oxy)phenylamino) carbonyl)2,6 diflouro benzamid, Triflumuron: 2-Chloro-N-(((4- (tri- flouromethoxy) phenyl)-amino-)carbonyl) benzamide, or a triazin such as N-cyclopropyl- 1 ,3,5 -triazine-2,4,6-triamin or other insecticides with a sterilizing effect on adult mosquitoes.

Another way to overcome resistance problems is the traditional use of synergists. Piperonyl butoxid and sesamex are traditionally used to combine with pyrethroids to overcome enzymatic based resistance mechanisms. Further DEET, usually used as a repellent, has shown to have synergistic abilities to organophosphorous and Carbamates, but is difficult to integrate for a prolonged effect due to its high vapor pressure (Vincent et al, 2004). Other biocides may show synergistic effect due to their interaction with detoxifying resistance mechanisms.

Integrating of such biocides that maybe are registered as insecticides may be included, provided they are not innate unstable or with high vapor pressure. The repellent may work in a mixture with the insecticide or acaricide or by its own abilities.

Repellent are selected from DEET: Ν,Ν-Diethyl-meta-toluamid; DEPA (N,N-diethylphenyl- acetamid; 1-(3-cyclohexan-1-yl-carbonyl)-2-methylpiperine; (2-hydroxymethylcyclohexyl); acetic acid lactone; 2-ethyl-1 ,3-hexandiol; indalone; MDNA: Methyl-neodecanamide; and pyrethroids not used as insecticides such as Esbiothrin: {(+/-)-3-ally62-methyl-4-oxocyclopent-2- (+)-trans-chrysanthemate.

Pyrethroids and some repellents have chiral centers giving rise to two to several racemates or isomers. The list above also includes existing and chiral derived isomers, racemates and pure enantiomer or diasteomers produced to give enhanced effect or to reduce the insecticidal or mammalian toxicity while increasing a specific activity as durability, repellent or deterrent effect or narrowing the activity to a special groups of target insects or acarinae.)

Herbicides, especially algacides, and bacteriocides or bacteriostatics may be integrated to prevent growth of algae and bacteria on the final product or to obtain a synergistic effect. A person skilled in the art can select among these from criteria of thermal stability, solubility in oil, low mammalian toxicity and low vapour pressure. Negative, chemical interactions between active ingredients should be avoided. The active ingredients in form of insecticide, acaricide, biocide, repellent, herbicide, bactericide or bacteriostatic mentioned in the present invention may be included in technical grade in a master batch in powder, granular or fluid form or added to the basic synthetic material just after it's polymerization. These intermediate forms are also included in the present invention. The active ingredients may also be added undiluted or diluted with inert material directly to the final process step when forming the yarn fibre or film. When more than one insecticide, acaricide, biocide, repellent, herbicide, bactericide or bacteriostatic are added, they may be added during various step of the production process. Some active ingredients are very temperature stable and can be added just after polymerization of the synthetic, whereas other active ingredients can only be added later in the production process to avoid evaporation or destruction. Such addition may be in the latest stage of the extrusion or post extrusion in the form of a coating. Modern extruders can be combined so that the same spinerette is fed by two extruders each carrying a different insecticide and produce different filaments yarns thereby carry different insecticides before the yarn is formed e.g. by twisting. Several ingredients may be added mixed or in separate master batches before mixing into the final mass for production, often as extrusion. Additives to protect the active ingredients against destruction in the intermediary or final production process can of course with advantage already be mixed into these intermediary forms as a master batch.

A typical amount of active ingredients is between 0.001 and 5% (dry weight) of the (dry) weight of the fabric or netting dependent on the insecticidal efficacy of the insecticide.

A preferred amount is between 0.05 and 2 % of the fabric or netting dependent on the insecticide. As understood by the skilled person in the present context - this may alternatively be expressed as that the effective amount of the active ingredient is preferably from 0.001 % to 5% dry w/w of the polymer composition.

A polymer composition - Polyethylene (general formular (Ch -CI-^n)

Polyethylene is a polymer consisting of long chains of the monomer ethylene. Polyethylene is created through polymerization of ethene. Polyethylene is classified into several different cat- egories based mostly on its density and branching. The mechanical properties of PE depend significantly on variables such as the extent and type of branching, the crystal structure, and the molecular weight. Polyethylene has been known for many years and the skilled person knows the different compositions to mix such as a HDPE, LDPE, LLDPE and MDPE. These are standard provided in the industry. Polypropylene may be also be used and mixed of polyethylene and propylene also. Also, copolymers comprising butene may be used.

In a preferred embodiment, the matrix comprises at least 60% of High-Density PolyEthylene (HDPE) or at least 80% of High-Density PolyEthylene (HDPE).

Polyethylene compositions can be made from different polyethylene polymers; these are LDPE, LLDPE, MDPE and HDPE.

LDPE (linear density polyethylene) is defined by a density range of 0.910 - 0.940 g/cm ³ . Generally, LDPE has more branching (on about 2% of the carbon atoms) than HDPE, so its inter- molecular forces (instantaneous-dipole induced-dipole attraction) are weaker, its tensile strength is lower, and its resilience is higher. Also, since its molecules are less tightly packed and less crystalline because of the side branches, its density is lower.

LLDPE (Linear low-density polyethylene is a substantially linear polymer (polyethylene), with significant numbers of short branches, commonly made by copolymerization of ethylene with longer-chain olefins.

MDPE is medium-density polyethylene is a substantially linear polymer of polyethylene with shorter chain length than HDPE. MDPE is defined by a density range of 0.926-0.940 g/cm ³ . HDPE (High-Density PolyEthylene) or PolyEthylene High-Density (PEHD) is a polyethylene thermoplastic made from petroleum. HDPE has little branching, giving it stronger intermolecu- lar forces and tensile strength than lower-density polyethylene. It is also harder and more opaque and can withstand somewhat higher temperatures (120 °C for short periods, 1 10 °C continuously). High-density polyethylene, unlike polypropylene, cannot withstand normally- required autoclaving conditions. It is understood herein that polymers as such or mixtures thereof; LDPE, LLDPE, MDPE and HDPE are polyethylene compositions.

The industry supplies the market with masterbatches. These are ready products and may already comprise an active ingredient and additives selected and disclosed herein. The masterbatches are thereafter processed into yarns and textile products as described herein.

The masterbatches may be selected from polyethylene, polypropylenes, or mixtures thereof using different polymer grades (HDPE, LDPE, and LLDPE) also. Such compositions are known to the skilled person. Preferred polyethylene compositions comprise the following composition: in percent of weight of the total composition:

HDPE: 50-90 % wt of total composition

LDPE: 0-20 % wt of total composition

LLDPE: 0-20 % wt of total composition

MDPE: 0-100 % wt of total composition

Polyethylene wax: 0-10 % wt of total composition

Additives chosen from the list:

Additives may be selected from the group consisting of UV filters, Tinuvin 494, Tinuvin 327, and Uvinul 3029 as described herein.

Additives maybe chosen in the range from 0.05 to 5% wt of the total composition. More preferred are: in percent of weight of the total composition:

HDPE: 60-85 % wt of total composition

LDPE: 5-15 % wt of total composition

LLDPE: 5-15 % wt of total composition

MDPE: 0-40 % wt of total composition

Polyethylene wax: 0-5 % wt of total composition

Additives may be selected from the group consisting of UV filters, Tinuvin 494, Tinuvin 327, and Uvinul 3029 as described herein.

Additives maybe chosen in the range from 0.05 to 5% wt of the total composition.

And most preferred are: in percent of weight of the total composition:

HDPE: 70-85 %

LDPE: 5-10 %

LLDPE: 5-10 %

MDPE: 0-10 %

Polyethylene wax: 0-5 %

Additives may be selected from the group consisting of UV filters, Tinuvin 494, Tinuvin 327, and Uvinul 3029 as described herein. Additives maybe chosen in the range from 0.05 to 5% wt of the total composition. Additives- release (migration) compositions

Polyethylene compositions as relevant herein may contain additives such as stabilizers, pigments, flame retardants and the like. In release (migration of active ingredients) compositions different types of additives can be used and these are known to the skilled person. For example, Ciba Specialities published in 1998 a guideline which additives to use to influence interaction of insecticides in polyethylene. Therein is named Tinuvin 1 1 1 , Tinuvin 494, Tinuvin 492 and NOR Hals (alkoxyamine hindered amine stabilizer), Chimassorb 81 , Chimassorb 944,1 19. EP429731 (1989) and US5948836 also discloses such additives in relation to polyethylene and insecticide (resistance of the antioxidant system to pesticides).

WO2003063587 (inventor Skovmand) discloses the role of additives such as triazine derivative as a migration inhibitor (as e g Flamstab or Tinuvin 494). Therein is disclosed also that Chimassorb 81 can be used as a migrating UV filter. For example page 14 lines 4-10

In WO20101 15709 there is describes additives and lists possible additive the skilled person may use to make a composition where the active ingredient migrates in a controlled way. The additives as listed in WO20101 15709 are used as references herein.

Present invention discloses a method of heat treatment.

The heat treatment method may be applied in different ways. The step of a heat treatment may be applied at a constant temperature selected from 80 °C to 130 °C for a selected time applied heat from between 10 to 120 seconds or heat treatment is applied gradually at a temperature from 80 °C to 130 °C for a time applied heat of between 20 to 120 seconds. Both methods result in controlled migration of the active ingredient. By present invention, several possibilities are now available to the skilled person how to make a textile product according to the present invention.

Described below are several possible ways of producing a polyethylene yarn and/or polyethylene textile product comprising an active ingredient (for example an insecticide) comprising the herein disclosed step of heat treatment obtaining thereby the improved migration properties as defined herein.

Gradual heat treatment or constant heat treatment.

Heat treatment may be done gradually by increasing the temperature from 80 °C to 130 °C for a time applied heat of between 20 to 120 seconds or constant applying temperature of 80 °C to 130 °C for a time applied heat of between 20 to 120 seconds.

Gradual heat treatment is applying heat from 80 °C to 130 °C for a selected time applied heat from between 10 to 120 seconds, i.e. slowly increasing the temperature within the time inter- val (10 to 120 seconds). This heat treatment as shown herein is very effective way of obtaining a textile product of the present invention.

Constant heat treatment is another way of obtaining a textile product of the present invention. Constant is denoted herein a choosing a fixed temperature of heat treatment, for example

90°C for 15 seconds but keeping the temperature constant for a chosen amount of time within the time interval as disclosed herein.

The choice of method of applying the temperature either gradually or constantly may depend on whether yarns are stretched or not stretched and also depends on cost during manufacturing process. In the manufacturing of textile products particularly bed nets, often a large amount of ordered at the same time. The manufacturer has to react quite fast in order to produce such high amounts and may have to buy in and make yarns to make the bed nets. The manufacturer can thus has to be able to handle different yarns types i.e. one batch or lot maybe relaxed yarn and the other batch or lot maybe not relaxed.

The present method applying heat is effective in the process using both relaxed yarns and not relaxed yarns, and this gives the manufacturer flexibility in the production operation.

The present invention leads to a polyethylene yarn and/ polyethylene textile product with high washing resistance and high mortality and controlled migration.

1 ) The yarn is relaxed and the textile is not or very little stretched

Yarn comprising an active ingredient produced using a heat setting step and thereafter the textile is made and the textile is heat treated.

Yarn may be relaxed by heat setting and not or very little stretched may be applied during heat setting. In this case, it is not necessary to apply heat treatment as disclosed herein - gradually. Very little may be less then 5%.

Embodiment a

Accordingly, a polyethylene fiber or products made from the polyethylene fibres of the present invention, wherein the method comprising the following steps: i) heat set the yarns obtaining relaxed yarns;

ii) knit or weave the yarn of step i) into a textile product;

iii) apply to the textile product of step ii) a heat treatment at a constant temperature selected from 80 °C to 130 °C for a time applied heat selected between 10 to 120 seconds. As the yarn is already stretched and relaxed (step i) and ii), it is not necessary to gradually increase the temperature of the heat treatment. This is important, as not relaxed yarns made into a textile product which are then subjected to a heat treatment of present invention results in breakage of the textiles and the textile product is simply not strong enough, i.e. the fibres have not enough strength.

2) The yarn is not relaxed -stretching is done while heat setting

A yarn comprising an active ingredient may be stretched while heat set with standard meth- ods. Both stretching and heat setting are standard methods and may be applied in combination.

Embodiment b

As the yarns have been relaxed, they may be stored after production until needed for knitting or weaving or may be directly used for knitting into a textile product. An embodiment is a polyethylene yarn according to the first aspect.

3. Yarn not heat set - heat setting combined with heat treatment

Yarn is produced and not heat set and thereafter the textile product is heat set AND heat treated at a temperature from 80°C to 130°C applied for duration of 15 to 80 seconds as with steps of present invention. Such yarns may be only stored for a short time (less than 14 days) and afterwards made into a textile product (i.e. a bed net) by knitting or weaving or may alternatively be used directly after production. Embodiment c

Accordingly, a polyethylene fiber or products made from the polyethylene fibres of the present invention, wherein the method comprising the following steps: i) prepare a polymer composition and extrude to obtain a yarn;

ii) knit or weave the yarn of step i) into a textile product;

iii) stretch the textile product while heat setting;

iv) apply heat treatment gradually at a temperature from 80 °C to 130 °C for a time applied heat of between 10 to 120 seconds. Polyethylene molecules get truncated and twisted and relaxed to random orientation by heat setting, and then during the stretching, the get orientated (parallel orientation). For this reason it is important to heat treat after stretching or stretch while heat setting. In this way, a textile product is obtained which is strong (tensile strength) and the active ingredient migrates as disclosed herein. The textile product obtained by the method steps i) to iv) and gradually heat treated as described above, is also heat set at the same time. Such process is an economically beneficial method and it is an advantage for the manufacturer to com- bine the two methods in one treatment (cost of energy consumed by heating).

A heat treatment at a temperature of 80 °C to 130 °C for a time applied heat of between 10 to 120 seconds

The methods of heat treatment are well known to the skilled person and are the same as for heat setting. Below some examples of method used for heat setting which may be chosen for the herein described heat treatment method.

Any method available to the skilled person may be used to heat treat according to present invention. This may be by hot air using a stenter or infra red ovens or others known.

Heat setting method (apparatus description)

Heat setting is a known process and done by for example Stenter machines. Such machines have a dimension of for example 2400mm to 2600mm width and consist of a series of connected heating chambers that can be set at chosen temperatures. A stentor of 6 chambers may be approximately 18 m long. For Knitted fabric such chambers are used for heat setting. A simpler version is a tunnel with a series of IR tubes where the net pass slowly. Since the heating here is a function of direct and indirect heating, it is more difficult to control and depends to some degree of the colour of the yarn. A laboratory version of the stentor was used for more precise dosage of time and temperature, but can only work with one chosen tem- perature per test, e.g. 1 10°C in 30 sec.

In the experiments disclosed herein, heat treatments were done in with the 3 types of heat setting "ovens" with air temperatures varying between 80°C and 120°C, with a time exposure of between 6 seconds and 120 sec.

Preferred is a heat treatment temperature of 80°C +/- 5°C and not higher then 200°C, more preferred from 90°C to 130°C, most preferred 1 10°C to 120°C.

Duration of heat setting

Duration of heat treatment according to the present invention is adapted to the temperature chosen.

Generally, for optimal cost of production, the faster the heat setting duration the better. Production scale testing has shown that duration of less than 10 seconds at a temperature up to 120°C has very limited effect, and that for 80 seconds at a temperature of 1 12°C is very effective, but due to the longer time provides a lower capacity thus higher production cost.

The exact chosen temperature and time according present invention depends from factory to fact and obviously which type of product is manufactured and which type of yarns (stretched or not stretched are used). For example, in case the net needs stretching and to avoid that the net is split apart during the process, the stretching of the net cannot take place at the peak temperature of the process and stretching, heat setting and heat treatment are taken place in separate parts of the heat setting oven, optimally with less stretch in the oven, where the heat treatment takes place to avoid that the net split apart.

Therefore, as also disclosed herein, there are different ways of choosing the disclosed heat treatment interval of temperature and duration of heat treatment applied to fibres, yarns and textile products.

Method of heat treatment and/heat setting.

Often stentors are used and are well known in the textile manufacturing processes. In the stentor, the net pass through a series of ovens where the air is heated either by electric heaters or by heated oil. Air blowers blow over the heated surface to the net. The temperature in each oven can be set individually, but since they are connected as one long tunnel, there is a limit to how temperature difference can be regulated.

Infra red ovens are used for the smaller units. These are gas driven or electrical heating units that radiate heat toward the net and the heating is thus directly from absorption of the IR radi- ation and indirect heating from the air in the unit.

Other methods of heat setting may be applied and these are all known to the skilled person.

The used machine is not critical, critical is as described in present invention to heat treat choosing the herein disclosed intervals of heat temperature and time.

Heat treatment temperature

The temperature may be set on the apparatus in the factory is accurate of approximately +/- 3°C and the operator may adjust this during the manufacturing process. Herein disclosed in a temperature setting of temperature of 80 °C to 130 °C either chosen one setting (e.g. 80°C) or as described herein a gradually increase from 80°C to 130°C for a duration in time as disclosed herein and these ranges can easily be set in a factory using present techniques. Preferred is for a selected time from between 10 to 120 seconds. Accordingly, an embodiment is a method to manufacture a polyethylene fiber or products made from the polyethylene fibres (e.g. yarns and/or textiles) comprising an active ingredient wherein the method comprises a step of heat treatment of the polyethylene yarn or products made from the polyethylene yarns in a temperature range from 80 °C to 130 °C for a selected time from between 10 to 120 seconds.

Duration of the heat setting (time of treatment)

The time set as disclosed herein is a time applied heat of between 20 to 120 seconds. This means that the heat is applied to the polyethylene fiber or products made from the polyethyl- ene fibres, such as textile product comprising an active ingredient.

A washing resistance according to WHO/CDS WHOPES/GCD PP/2005 guidelines

As understood herein, the WHO test protocol as referred to herein as WHO REF 1 describes in detail the protocol for washing under laboratory conditions. The washing test is used as a standard method to estimate the endurance and life time of the textile product. The principle is that by washing the active ingredient is removed from the surface of the textile yarn and due to the composition of the polymer engineered as such that new active ingredient comes to the surface after washing, is available and chemically intact, to obtain biological activity measured in killing (mortality) at least 80% of mosguitoes of a tested population. The high the amount of washes and the higher the mortality achieved, the better suitable is the textile product for killing insects e.g. mosguitoes and hereby suitable for the prevention of malaria infection.

Different yarn types and different fiber types

Multiple active ingredients in yarns in textile products is another option a skilled person can chose and use the present invention.

As known from the prior art (for example publication WO 20101 15709 (Ole Skovmand), the skilled person can for example use two different yarns with each it's different insecticide and now by present invention heat treat these yarns and obtain a yarn or fiber with improved washing resistance and migration properties as shown herein.

Different yarn types can be used to construct the bed nets with improved migration profiles which has a more stable migration and permanent. Cloth and especially trousers and socks may be formed from yarns of multifilament polymers that release insecticides that are not skin irritating and very low toxic, such as permethrin and even less toxic, etofenprox, but also active ingredients that are registered as repellents.

Insect As named herein, the present invention can also be used to make cloth from the yarns with insecticides. The choice of such active ingredients than depends on the target. The skilled person will chose suitable active ingredients such as an acaricide in case the target is to kill ticks and the skilled artisan may chose other active ingredients for other target insects.

Malaria is described herein as the major target for the protection of humans using the herein described insect textile products in the form of bed nets, nets, curtains, tsetse traps, roofing material or tarpaulins. A typical embodiment of the insect textile product is a bed net, another embodiment is a curtain.

Non woven product

The polyethylene polymer compositions, fibers and yarns of present invention may also be used to make non woven based products. For non woven products polyethylene fibers of present invention may be prepared and used in a non woven process for making non-woven products such as cloths or sheets. Such can be used to protect humans or crops for agriculture. Such products may also be heat treated as present invention describes obtaining products with improved migration properties i.e. with increased killing effects as demonstrated herein.

EXAMPLES

Example 1 : Method to measure mortality (killing) or knock down of mosquitoes in vivo with a sufficient insecticide dosage: (according to WHO World Health Organization, herein reference 1).

The term "sufficient dosage" herein is defined by: 50, 3-4 days old female mosquitoes are exposed to textile (net) under standard WHO cones, 5 in each cone, for 3 min. The net must be able to kill at least 80 % of mosquitoes of a susceptible (no insecticide resistance) strain of mosquitoes after 24 hours or to paralyze (called knocked down) at least 95 % within 60 min. Mosquitoes are hold in cups with sugar water available for the 24 hr, at 25+-2°C and 75+-10 % RH. Alternatively, 5-8 days old adult female mosquitoes are released in a tunnel (square section 25x25 cm) made of glass, 60 cm length. At each end of the tunnel, a 25 square cm cages is fitted (extension) and covered with polyester netting. At one third of the length, a disposable cardboard frame is placed with the netting sample. The surface of the netting availa- ble to mosquitoes is 400 cm ² (20x20 cm), with none holes each 1 cm diameter: one hole is located at the centre of the square; the other eight are equidistant and located at 5 cm from the border. In the shorter section of the tunnel, bait (guinea pig for Anopheles gambiae) is placed, unable to move. In the cage at the end of the longer section of the tunnel, 100 females are introduced at 18:00. Females are free to fly in the tunnel, but have to make contact with the net and locate holes before passing trough to reach the bait. The following morning 9:00, mosquitoes are removed and counted from each section and immediate mortality and blood feeding status is recorded. Delayed mortality is recorded on live mosquitoes transferred to cups with sugar water and after 24 hr. Mortality must be at least 80 % and blood feeding inhibition at least 90 % for a textile (net) still sufficient active. (Guidelines for laboratory and field testing of long lasting insecticidal mosquito nets, WHO/CDS/WHOPES/GCD PP/2005 (reference 1 ).

Example 2: Method to perform washing test - WHO standard test for net swatches,

WHOPES2005/11(WHO REF 1 page 4)

Wash resistance

The resistance of an LN to washing will be determined through standard bioassays carried out on nets washed at intervals required for regeneration (as determined above), using the standard WHO wash, and dried and held at 30 °C. Bioassays will be done after 0, 1 , 5, 10, 15 and 20 washes or more as necessary. Each bioassay should be done jus t before the next wash. Regression curves are drawn using respectively percentage mortality and knock down (KD) versus number of washes. The number of washes providing mortality and/or KD above the cut-off point (more than 80% mortality after 24 hours and/or above 95% KD after 60 minutes post-exposure) is reported. If an LN falls below the cut-off point, the study should continue until 20 washes are reached; a tunnel test (see chapter 2.2.2 WHO REF 1 ) should

then be conducted.

WHO washing procedure Net samples (25 cm x 25 cm) will be individually introduced into 1-1 beakers containing 0.5 I deionized water, with 2 g/l soap (pH 10-1 1 ) added just before and fully dissolved. Beakers were immediately introduced into a water bath at 30 °C and shaken for 10 minutes at 155 movements per minute. The samples were then removed and rinsed twice for 10 minutes in clean, deionized water in the same shaking conditions as stated above. Nets were dried at room temperature and stored at 30 °C in the dark between washes.

Example 3: Standard test Efficacy (WHO REF 1)

Efficacy - Bioassavs

Five susceptible, 6 non-blood fed, 2-5-day old Anopheles (species to be stated in the test report) mosquitoes will be exposed to netting materials (25 cm x 25 cm) for 3 minutes, under standard WHO cones, after which they are held for 24 hours with access to sugar solution. KD is measured after 60 minutes post exposure and mortality after 24 hours. At least 50 mosquitoes on each net (10 replicates) and samples from four different nets should be tested. Results should be reported for each net tested along with the pooled results (5 x 10 x 4 = 200 mosquitoes). Mosquitoes exposed to untreated nets are used as controls. Bioassays will be carried out at 25 + 2 °C and 75 + 10% RH. Nets washed at least 20 times that cause >80% mortality and/or >95% KD meet the criteria to undergo Phase II testing.

Example 4: Different combinations of temperature and time for heat treatment, two

25 sample composition. The heat treatment is constant applied.

Temperature Duration 0 0 5 5 10 10 15 15 20

Heat treatof heat wash wash washes washes washes washes washes washes washes ment C° treatment

in se% 60 % 24 % 60 % 24 % 60 % 24 % 60 % 24 % 60 conds min hour min KD hour min KD hour min KD hour min KD

KD death death death death

80 C1 30 100 100 96 98 56 62 stop

90 C1 10 100 100 96 82 72 74 stop

90 C1 30 100 100 100 92 88 64 stop

80 C2 30 100 100 98 92 80 88 72 58 stop

90 C2 10 100 100 98 90 70 62 stop

90 C2 30 100 100 96 96 96 96 96 90 98

Control (no 0 0 0 0 0 0 0 0 0 heat applied) Table 1. Different combinations of temperature and time were applied to textile product sam- pies coded C1 and C2 representing a different polymer composition (C1 has a different polymer composition as compared to C2). The textile product samples were heat treated according to the settings in the table and washed according to WHO REF 1 and biological efficacy measured according to WHO REF 1 (mortality and KD as described herein). Note that once the mortality is below 80%, the washing test and biological efficacy (bio-assay) is stopped as indicated in the table with "stop".

Conclusion

Composition C1

It is seen that in case of composition C1 received a heat treatment up to 90°C for 30 seconds and is not improving wash resistance as measured in WHO REF 1 wash and bio- assay method. The heat treatments of C1 composition only reached 5 washes.

Composition C2

Composition C2 was heat treated with 90°C for 30 sec (see bold C2 in the table 1 ) is better than 80°C for 30 sec, whereas the treatment of 90°C for 10 sec is not improving washing resistance and biological efficacy.

Overall conclusion

Heat treatment is a proper combination and selection of time for heating and temperature.

Example 5: Different compositions of with migration inhibiting and accelerating additives including polyethylene wax was used to create products that had more or less increased wash resistance observed in a WHO designed bed net test program, WHO-REF1.

The results are presented below in table 2. Textile Heat 80% Mor80% Mor80% Mor80% Mor80% Morsample treatment tality tality tality tality tality

Yes = 1 0 washes 5 washes 10 washes 15 washes 20 washes

No = 0

335 0 100 60 35

335 1 100 100 100 90 90

336 0 100 87 80

336 1 100 100 98 99 98

337 0 100 96 80

337 1 99 100 91 99 100

338 0 100 82 64

338 1 100 100 99 99 100

339 0 100 66

339 1 100 100 94 97 94

340 0 100 91 84

340 1 88 91 99 100

341 0 100 73

341 1 87 100 97 91 100

342 0 100 77 18

342 1 100 100 99 98 99

Table 2. Samples were heat treated at 120°C for 60 sec or not heat treated as control at a and thereafter submitted to the standard washing test of REF 1 (WHO).

It can be seen that for all textile product samples (335 to 342), the heat treatment provided much better wash resistance than for the nets without heat treatment measured in WHO REF 1 wash and bioassay method and nearly all nets without heat treatment provided less than 80 % mortality after 5 or 10 washes.

Example 6: A polymer compositions comprising additives were heat set at specified conditions, washed and tested for efficacy according to WHO REF 1.

Table 3: Samples are heat treated in laboratory heat setter and tested in wash/bioassay cycles according to WHO-REF 1. The table 2 shows how many washing cycles passed before less than 90% and 80 % absolute mortality is reached.

ND denotes "not determined" (measurement was not performed).

Samples identification: 392 to 393.8 are the same composition.

Sample 392 and 393 are the same composition and the indicated 393.1 to 393.8 indicate the heat treatment according to the table (meaning 393.1 is 90C heat treatment). 392 and 393 both have C81 and Tinuvin 494.

Conclusion (table 3)

Polymer compositions sample numbers 393.4, 393.5, 393.6, 393.6, 393.7 and 393.8 are best performing (20 washes was reached) as shown in the table with high mortality (at least 80% absolute mortality) and with high remaining total amount of deltamethrin in the yarn (before washing there is approximately 1.47 g/kg deltamethrin present). With > 20 is meant that the test may continuo and finding high mortality (at least 80%). If the test would show lower than 80%, the washing test would be stopped. Example 7: Constant heat treatment impact on washing resistance and obtained biological activity is temperature dependent

Table 4. Samples (yarns not stretched) as indicated in table 3 (see index below) were submitted to constant heat treatment (temperatures selected were 80°C - 90°C - 120 °C) for selected 30 - 45 - 60 seconds and tested for washing resistance according to WHO-REF 1 protocol; as response was taken the percentage (%) of mosquitoes knocked out after 60 min (KD ₆₀ ) and after 24 hours (%) of % mortality mosquitoes.

Textile net sample 392 was made of stretched yarns and heat set in factory at 80°C constant and 60 seconds. Textile net sample 393 was not heat set, then heat treated in the heat setter (oven) as described in the table 4.

Conclusion:

It can be seen that 393.8 and 393.9 achieve 100% mortality after 15 washes and also 100% mortality when the same samples are re-tested after 10 days (understood herein as this is a 16 ^th wash - re-generation). The obtained migration effect is stable. It can also be seen that other samples after regeneration time (after for example 10 days) also improve performance of mortality even thought the first 15 washes obtained very low mortality. This effect is known and is due to the continuous migration of insecticide in the time. However, samples 393.8 and 393.9 have a very regular and very high release patron as tested using the WHO test protocol reference 1 herein. Samples 393.8 and 393.9 have been heat treated at 120°C for a duration of 45-60 seconds which is within the preferred heat treatment.

Textile product samples that were heat treated at 80°C improve with time, meaning they have a slow migration/regeneration of insecticidal activity, but they do not reach as high mortality level of those heat set at 100 °C and 120°C. The mortality effect after several washes is clearly temperature dependent.

Table 4 also shows that heat treatment was effective for the control of migration of active in- gredient in the range from 80° to 100°C measured in bio-assay according to Who REF 1.

Example 8: Gradually increasing the temperature from 80°C to 110°C-120°C is an alternative way of heat treatment useful in case the yarn are not relaxed before knitting or weaving. Figure 1 show the effect of gradually increasing the temperature from 80°C to 1 10-120°C which also results in improved washing resistance (high mortality). The gradually increasing the temperature is a preferred method herein which combines heat setting and heat treatment making it a cheaper process to run for high output yarn and/or textile product production. As data show herein, the method using gradual increasing the temperature is as good as a direct heat treatment of the interval disclosed herein.

Note that in figure 2, textile samples were treated as treated in figure 2 - samples removed of the wash/bioassay cycles after 0, 5, 10, 15 and 20 washes and thereafter analyzed for deltamethrin content by the method described in example 5. Yarns as used to produce the textile nets in figure 2 were not relaxed. Yarns were heat treated in the factory with either constant or increasing/decreasing temperatures with the range as disclosed herein. The time of treatment was 31 seconds.

Example 8 is a test done in a factory, where the nets are exposed to either constant tempera- ture 80°C or gradual increasing the temperature from 80°C to 1 10°C or 120°C (figure shows four chosen ranges; 80-80-80°C (constant is control in the experiment), 80-90-1 10°C, 80-90- 120°C and 80-100-120°C).

In the case that nets (yarns or fibers) are exposed to either constant 80°C or gradual increas- ing to 1 10°C or 120°C (herein a combined heat setting and heat treatment), the mortality improves with heat setting and heat treatment at higher temperature (100°C to 120 C°) and that the improved migration effect is permanent and long lasting.

Conclusion - FIG 1

The heat treatment effect wherein the temperature is gradually increased starting from approximately 80°C +/- 2°C increasing to 120°C +/- 2°C. Gradually increasing the temperature (heat setting) results, as figure 1 shows in very high washing resistance (20 washes) and very high and stable and permanent mortality (100%). Example 9: Method of determining deltamethrin content in polyethylene fibers

This is a known method to the skilled person and reference is done to Deltamethrin content determination as published standard method CIPAC/4673/m with note that the extension of the CIPAC method 333/LN/(M)/3 (CIPAC/4673/m) for determination of deltamethrin in incorporated into polyethylene LN was accepted as provisional CIPAC method in 2009.

Example 10: Analysis of amount of deltamethrin in the yarn/fiber as measured after cycles of washing - reference to the samples of figure 2 which after being used to measure mortality were analyzed for total amount of deltamethrin present.

Conclusion - FIG.2

Statistical analysis shows that the curves are parallel, meaning that the improved washing resistance is not linked to a faster depletion. As explained above under example 4, mortality is stable and the migration of insecticide on the surface is constant and well under controlled. The controlled permanent and stable migration is proven also by the fact the amount of deltamethrin present is not depleted at once. One may assume reading the data of example 4 that such good results may be achieved by fast depletion of high amounts of deltamethrin due to applied heat setting. This would be a worse result as this is not understood herein as improved migration properties. Improved migration properties is a polyethylene fiber or yarn or made textile products thereof, wherein the active ingredient migrates sufficient amount of insecticide to reach very high mortality (at least 80% and most preferably 100%), and reaches high amount of washes at least 20 washes and has a suitable amount of insecticide in the polyethylene composition as a reservoir (no fast depletion). As the start concentration is approximately 1.8 gram deltamethrin/kg of net, after 20 washes still there is as the figure 2 shows, 1.4 gram deltamethrin/kg of net present as a reservoir in the polyethylene composition. This is an approximate migration loss of 20 to 25%. Example 11 : Efficacy of the heat setting in specific interval of temperature and duration of heat treatment.

Example 1 1 exemplifies an experiment done under laboratory conditions (whereas others were done under factory settings). It merely demonstrates that the results are reproducible under both conditions (laboratory and factory).

Table 5. Samples as indicated in table 4 (see sample identification below) were submitted to 5 heat treatment (temperatures selected were 80°C - 100°C - 1 10 °C- 120 °C) for 45-60 seconds and after heat treating, thereafter samples were tested for washing resistance according to WHO-REF 1 protocol; as measurement was taken the percentage (%) of mosquitoes knocked out after 60 min and after 24 hours (%) mosquitoes dead.

10 Experimental description:

A non heat treated sample was cut into 20 pieces and heat set in a laboratory stentor, one chamber at different temperatures and time. All samples were then sent to a bioassay that determined KD at 1 hour and mortality at 24 hours according to WHOPES REF1 .

15 393.1-393.9 represents the same polyethylene polymer composition as 393 but indexed 1-9 according the applied heat treatment temperature and time of heat treatment as indicated in table 5.

Conclusion Example 1 1

20 The results in table 4 show controlled migration of insecticide due to the chosen interval of heat setting and the duration of chosen heat treatment. All samples 393 to 393.9 show improved washing resistance versus the control. All heat treated samples tested in the range of temperature from 80°C to 120°C for duration of 45-60 seconds have improved migration e.g. improved washing resistance and high level of mortality.

25

Table 4 also demonstrates that this is permanent and stable migration, understood herein as that is a constant sufficient amount of insecticide on the surface of the textile or yarn available to achieve high mortality according to WHO REF 1 protocol (biologically available). In other words, if there would be no controlled migration, the entire reservoir of insecticide present in the fiber would immediately be released and such result would be visible as no mortality would be measured even after 1 wash or even better noticeable after 5 washes. Such product would not be approved according to WHO REF 1 test protocol and obviously, such textile product may not be found on the market place for the control of malaria infection in humans.

Overall Conclusion

Heat treatment selected from the temperature interval from 80°C to 130°C for a selected duration of time as disclosed herein provides better bioassay results (i.e. high mortality) in wash resistant test.

Example 12: Strength of the yarn

Heat treated yarn have an altered strength. Yarn strength can be measure by the known standard method of tenacity. As used in yarn manufacture and textile engineering, tenacity denotes the strength of a yarn or a filament of given size and is an expression for the yarns breaking strength.

As for yarns, the skilled person may use this test to determine whether a polyethylene yarn or textile product made from such yarns comprising an active ingredient as disclosed herein, have been heat treated in accordance with the present invention.

REFERENCES

1. WHO/CDS/WHOPES/GCD PP/2005 - herein referred to as The "WHOPES 2005/11" wash test can be found in "Guidelines for Laboratory and Field testing of Long Lasting Insecticidal Mosquito Nets, WHO/CDSIWHOPES/CDPP/2005."

2. WO2008122287

3. WO0137662

4. WO20071444

5. WO2007085640

6. GB 2276171

7. EP1411764B1

8. JP8302080

9. US4897902

10. US478633