WO2011124228A1

WO2011124228A1 - A biocidal polyolefin yarn with 3-12 filaments

Info

Publication number: WO2011124228A1
Application number: PCT/DK2011/050116
Authority: WO
Inventors: Matthieu Zellweger; Michael Stanley Pedersen; Sebastien Gouin; Mikkel Vestergaard Frandsen; Sicco Dirk Roorda; Huyen Thanh Hoang
Original assignee: Vestergaard Frandsen Sa
Priority date: 2010-04-07
Filing date: 2011-04-07
Publication date: 2011-10-13
Also published as: CN103119208A; AP2012006555A0; TW201202497A

Abstract

A multifilament thermoplastic polymer yarn, into which a biocide, especially an insecticide, is incorporated, where the number of filaments is 3 to12. The yarn is especially useful for a long lasting insecticidal net with polypropylene yarns containing Deltamethrin.

Description

A biocidal polyolefin yarn with 3-12 filaments

Field of the Invention

The present invention relates to a polyolefin multifilament yarn with incorporated bio- cide/insecticide. Especially, it relates to yarns for long lasting insecticidal nets.

Background of the Invention

In the field of long lasting insecticidal nets (LLIN), typically mosquito nets, mainly two principles are covering the market. The first principle relates to impregnation of woven nets, where the yarn is a polyester (PET=poly ethylene terephtalate) multifilament yarn. The second principle is a woven monofilament polyethylene (PE) yarn into which the insecticide is incorporated, that is, the insecticide distributed throughout the polymer matrix. Whereas an article according to the first principle with the polyester multifilaments has the advantage of a pleasant textile-like feeling, the second principle has the advantage of a one-step process, thus, cheaper production, which is highly important, as most of the long lasting insecticidal nets are distributed in poor areas and emergency situations, and the sponsors are demanding low cost.

In practice, polyester is not suitable for incorporation of the insecticide due to its high melting temperature of 256°C in contrast to the melting point of the polyolefins, for example 160°C for polypropylene (extrusion temperature typically above 190°C) and 138°C for high density polyethylene (extrusion temperature typically above 175°C). Also, polyester has a much higher glass-transition temperature than polyethylene, for which the glass transition temperature is below room temperature, which influences the migration properties. On the other hand, polyolefins are not suitable for impregnation due to their highly hydrophobic nature.

Although insecticidal anti flea multifilaments with 68 filaments for carpets are disclosed in US 5,028,471, multifilaments with incorporated insecticide have not found way to the market of mosquito nets. In this connection, it should be mentioned that the yarn as dis- disclosed in US 5,028,471 has a weight of 4080 denier, which is far too thick and therefore useless for mosquito nets.

Thinner filaments of 150-500 denier are disclosed in WO2008/123593 and WO2010/067902 by Sumitomo, wherein 6 strands are simultaneously extruded through an extrusion head with 6 holes in order to shape monofilaments. It discloses that such monofilaments can be used for nets, ropes and yarns. Also multifilaments are mentioned, although no number of filaments in such multifilaments is mentioned. Using the monofilaments of 170 or 200 denier for multifilaments in insecticidal nets is not useful, because such multifilaments would be too thick and stiff. For example, using all 6 strands of 170 denier from the extruder yields a 1020 denier multifilament yarn, which is unsuitable for mosquito nets. In Sumitomo's application US2007/0134495, extrusion is disclosed of 150 filaments from a single die in order to obtain monofilaments of 200 denier. It is obvious that these 150 filaments are not used for a single multifilament yarn.

WO2009/003468 by Vestergaard Frandsen discloses yarns with filaments containing different agents, for example two twisted monofilaments either alone in a yarn or in combination with a multifilament. No specific number of filaments for multifilament yarn is disclosed.

For the thin multifilaments in connection with LLIN, for example 36 filaments in a 100 denier yarn, as for the world leading LLIN PermaNet™, incorporation in a polyolefin is generally unsuitable, because these filaments are so thin that the insecticides will migrate to the surface too fast and the yarn will lose its insecticidal efficiency too quickly.

For these reasons, the market and research of LLIN have been divided into two very distinct areas, namely PET multifilaments with impregnated/coated insecticide and PE monofilaments with incorporated insecticide.

Although polypropylene (PP) has some advantages, for example a broad variety of resins with various melt flow indices, processing properties and mechanical properties, polypropylene nets do not have an important share of the market. This is so despite PP being being mentioned as an option in various patent applications, for example Bayer's WO2009/121580, Basell's WO2008/141915, or in CN1468984/CN1180139 by Shanghai Petro-Chem Co Ltd. However, as there is an ongoing effort in the field to achieve a higher standard, there is still need for improvements in the art.

Object of the Invention It is therefore the purpose of the invention to provide a new mosquito net with improved properties. Especially, it is the purpose to provide a yarn for a fabric where a biocide is incorporated in the yarn, and the fabric has a smooth textile-like feeling, because this is preferred by the users.

Description of the Invention

This purpose is achieved with a multifilament thermoplastic polymer yarn, optionally polyolefin yarn, into which a biocide is incorporated, where the number of filaments is 3- 12, for example, 5-9 or 6-8. Preferably, the biocide is an organic biocide.

The term "a biocide" is to be read as "a biocide or group of biocides", as blends of bio- cides can be used instead of a single biocide.

The term biocide covers the following non-limiting list of agents including insecticides and insecticidal synergists, insect attractants and repellents, insect-sterilising agent, entomopathogen agents, fungicides, bactericides, bacteriostatics, or herbicides or mixtures of at least two of these.

It has turned out for polymers, especially polyolefins, such as PE, but especially for PP, that a textile-like feeling can be achieved for a yarn with a low number of filaments, while still having a long lasting insecticidal release from the yarn. This fact makes the yarn highly suitable for long lasting insecticidal nets. Although an even number of multifilaments with 2, 4, 6, 8, 10, or 12 polyester or nylon (polyamide) filaments are known from US patent application No. 2004/0168479, this has not yet led to any inspiration for use in the LLIN industry. The trend in the field to keep the two sectors of multifilaments of PET and monofilaments of PE in the LLIN market apart with respect to impregnation and incorporation, respectively, has prevented trials to incorporate insecticide in multifilaments with a low number of filaments. Especially, it has not led to envisaging the fact that a narrow interval of only 3-12 or 5-9, for example 6, 7, or 8 insecticidal polymer filaments, especially polyolefin filaments, should be beneficial for insecticidal mosquito nets, or that a number of just 6, 7, or 8 PP filaments should be a good technical solution for LLIN with incorporated insecticide, especially Deltamethrin.

In connection with the term "multifilament yarn" it should be pointed out that this is to be understood such that the monofilaments are assembled and tightly grouped together into a single, continuous multifilament thread, for example by twisting. This is also the common understanding of the term "multifilament yarn". Such grouping together by twisting, interlocking, intertwining, entangling, plying is in contrast to the mere extrusion of 6 individual 170 denier filaments from an extruder head as disclosed in WO2008/123593 or the extrusion of 150 filaments of 200 denier as disclosed in US2007/0134496.

Advantageous thermoplastic materials therefore are polyolefins, especially polypropylene and polyethylene, including Linear Low Density PolyEthylene (LLDPE), Low Density Polyethylene (LDPE), Medium Density Polyethylene (MDPE), and High Density PolyEthylene (HDPE) or mixtures thereof. For example HDPE and LDPE or LLDPE can be advantageously mixed in order to obtain good migration properties. A non limiting example is a weight ratio of 5-20 or 5-11 or 8-10 between HDPE and LDPE or LLDPE in a polymer matrix for filaments. This is discussed in more detail in the Vestergaard Frandsen application WO2010/015256. However, other suitable candidates include plasticized Poly Vinyl Chloride (PVC), Poly Vinylidine DiChloride (PVDC), (PVDC), PolyVinylAcetate (PVAc), and PolyOxyMethylene (POM). In some embodiments, the polymer of the multifilaments comprises at least 90%, at least 95%, at least 98%, or at least 99% PP. The optimum thickness of the monofilaments depends on the number of filaments and the product to be provided with such multifilaments. For example, mosquito nets, typically, have a thinner yarn than greenhouse nets or insecticidal fences. An example of multifilament yarn thickness for LLIN against mosquitoes is 50-200 denier, especially 75- 150 denier, for example, 100 denier. For such filaments, a suitable weight is 12-17 denier, for example, 12-13 or 14-16 denier. This filament weight gives the optimal softness and long lasting action when used for LLIN as a polymer yarn, especially PP yarn, containing Deltamethrin.

For other applications, for example greenhouse nets and insecticidal fences, the multi- filament yarn may be thicker, for example between 150 and 1000 denier. Especially, for greenhouse nets or nets for covering agricultural areas, the thickness for the yarn is advantageously, although not necessarily, 200-800 denier. For fences at least partly surrounding an open-air agricultural area, the thickness for the yarn is advantageously, although not necessarily, 400-1000 denier. The principle of such fences for preventing low flying insects to enter such open-air area is explained in International patent application WO03/003827 by Vestergaard Frandsen.

Insecticidal nets made from a multifilament yarn according to the above, typically, has a mesh size of 1-5 mm, for example 1.5-2.5 mm when used against mosquitoes.

Although the invention is primarily directed towards LLIN/mosquito nets, it may also find application in other fields, such as biocidal woven or non-woven textiles. For preventing moth attacks on fabrics, it is not strictly necessary that the insecticide is migratably incorporated in the fabric material in a way, such that the insecticide migrates from inside the matrix, especially polyolefin matrix, for example PE or PP, to the surface of the yarn. However, for an LLIN to have insecticidal activity, the incorporated insecticide, for example Deltamethrin, is required on the LLIN's surface. In order for the biocide, for example insecticide, to reach the surface, the biocide is migratably incorporated and distributed, for example as a dispersion, optionally molecular dispersion, throughout the filament for gradual migration from inside the filament to the outer surface of it. From the outer surface, the biocide is released to the environment in various ways. For example, the biocide is an insecticide and is picked up by an insect upon contact.

The biocide may be added as part of a liquid or gel, or as a dry powder, for example crystalline powder, to the extrusion melt. Optionally, the particulate biocide in the polymer matrix need not be fully dissolved in the matrix but can stay as solid particles inside the matrix after extrusion. It may then slowly be dissolved as a result of the migration of the insecticide to the surface of the matrix. In other words, the particulate biocide acts as a reservoir inside the polymer matrix. Crystals in thermoplastic polymer fibres are discussed in South African patent application ZA2005/09810 by Moznet CC.

Net materials of one kind can be combined with other types of net materials; for example a mosquito net has a first net material for the roof different from a second net material for the side walls. An example of such a system is disclosed in WO2009/003469 by Vester- gaard Frandsen. The materials can be made of different polymers and/or with different contents of active agents. For example, the roof contains a synergist and the side walls contain an insecticide. Another example given in the same disclosure is use of different yarns in a single net.

For example, a multifilament first type of yarn with a biocide, for example insecticide or synergist, such as PBO, can be combined with a second type of monofilament or multifilament yarn having a different type of biocidally acting agent incorporated in its polymer matrix, for example another insecticide or synergist. These two types of yarn can be combined through a weaving or knitting process into a single type of fabric comprising the two different yarns. For example, each mesh in a net comprises the first and the second type of yarn; an example is a net made or warp yarn of the first type and weft yarn of the second type. Examples of such systems are described in Sumitomo's application W02010/016561 and in IIC's application WO2010/046348. Alternative combinations of different types of yarn includes a first type of a multifilament yarn having a biocide incor- yarn having a biocide incorporated and a second type of multifilament yarn, where a different biocidal agent is provided in a coating on the yarn.

For example, at least one filament of the multifilament yarn comprises Dinotefuran or Fipronil or both but not PBO or Deltamethrin and at least one other filament in the same multifilament yarn comprises PBO or Deltamethrin or both but not Dinotefuran or Fipronil.

In a further embodiment, a multifilament yarn is provided with incorporated biocide and which is coated with a coating comprising a different biocidal agent. The incorporated biocide, for example insecticidal synergist, may then migrate to the surface of the filament matrix and migrate further through the coating to the surface of the coating for release from the surface of the coating. An insect contacting the multifilament yarn would be exposed simultaneously to the migrated biocide as well as to the different biocidal agent from the coating for combined action. Examples are insecticides in combination with synergists or other insecticides. Examples of systems are disclosed in WO2009/003468 by Vestergaard Frandsen and in IIC's application WO2010/046348. The number of coatings with different agents is not limited to one; two or more coatings can be provided on the surface of the multifilament matrix.

A further option to be mentioned in connection with the invention is the possibility of having different biocides, for example insecticides and synergists, in different filaments as part of a multifilament yarn. Two types of filaments can be combined by plying into a single type of yarn comprising both types of filaments prior to a weaving or knitting process. Examples of such systems are disclosed in WO2009/003468 by Vestergaard Frandsen and in IIC's application WO2010/046348.

Whereas there is great success for using PE as a material in the market of LLIN, PP has not experienced the same attraction. One of the reasons is that PP does not provide as stabilizing a matrix as PE. Another reason is that PP yarns with Deltamethrin seem not to have a sufficient insecticidal function as expected.

Closer study of the problem by the applicant has revealed the insight that a PP matrix, for for example the commercial Ziegler-Natta type or the Metallocene type, has a detrimental effect on Deltamethrin incorporated in it. The detrimental effect is analogous to an alkaline effect on Deltamethrin when in water based environments. Deltamethrin is known to have a reduced lifetime in alkaline environments as compared to neutral or weakly acidic environments. However, the effect of this nature in PP is surprising because it is not expected that alkaline components are present in significant proportion in PP. Therefore, it is also surprising that the lifetime of Deltamethrin after extrusion of the polymer matrix into filaments can be prolonged in PP by adding acids into the polymer matrix before or during extrusion, which is a simple way to improve the insecticidal capabilities of PP remarkably.

Thus, it has been found that a polypropylene matrix can be changed advantageously, if the PP resin is mixed with an acid before the insecticide is mixed into the molten resin for extrusion. By this method, conditions can be achieved such that Deltamethrin has a longer survival time in PP making it suitable for LLIN applications. This finding is applicable in general for insecticidal PP matrices, also for PP sheets, but has special interest in connection with the multifilament yarn.

Thus, in a further embodiment, a multifilament yarn is provided according to the above. The yarn comprises a thermoplastic polymer matrix with a biocide migratably incorporated and distributed throughout the matrix for gradual migration of the biocide from inside the matrix to a surface of the matrix, wherein the thermoplastic polymer of the matrix comprises at least 75%, at least 90%>, at least 95% or 100% of polypropylene by weight of the thermoplastic polymer. In addition, also an acid is distributed throughout the matrix.

For example, the thermoplastic polymer of the extruded matrix in the form of a yarn is a blend of polymers and comprises at least 75% polypropylene homopolymer, for example at least 90% or at least 95% polypropylene homopolymer, or 100%) polypropylene by weight of the total thermoplastic polymer of the matrix. Optionally, the thermoplastic polymer of the extruded matrix is a blend of polymers only being homopolymers. In a further embodiment, a thermoplastic polymer, for example a polypropylene batch, is provided for extrusion, for example as one batch blended with other batches. A blend is provided by adding acid and a biocide to the thermoplastic polymer, for example to the batch. This blend may be obtained by blending both acid and biocide into the same batch, or there may be provided one batch with biocide and one batch with acid, which are then blended. This blend is then, optionally, mixed with one or more other blended batches and/or with a further pure thermoplastic polymer, for example polypropylene batch, before melt extrusion. Alternatively, the blend is directly melt extruded into a matrix in the form of a filament or multiple filaments. Thereby, the biocide and the acid are distributed throughout the matrix of the final filaments. Preferably, the incorporated biocide is then provided on the surface of the filament matrix by gradual migration of the biocide from inside the matrix to a surface of the matrix. As already outlined above, the thermoplastic polymer of the extruded filament matrix comprises at least 75%, at least 80%), at least 90%>, at least 95% or 100% of polypropylene by weight of the ther- moplastic polymer, The weight of the thermoplastic polymer of the matrix is determined without taking into account the weight of the other ingredients in the matrix, such as biocides, stabilizers, or biocide-supports.

Optionally, the PP batch is blended with another thermoplastic polymer. Advantageous thermoplastic materials therefore are polyolefins, especially polyethylene, including Linear Low Density PolyEthylene (LLDPE), Low Density Polyethylene (LDPE), Medium Density Polyethylene (MDPE), and High Density PolyEthylene (HDPE) or mixtures thereof. However, other suitable candidates include plasticized Poly Vinyl Chloride (PVC), Poly Vinylidine DiChloride (PVDC), PolyVinylAcetate (PVAc), and Poly- OxyMethylene (POM). In some embodiments, the polymer of the multifilaments comprises at least 80%, at least 90%, at least 95%, at least 98%, or at least 99% PP by weight of the polymer without other ingredients and at least one of the above mentioned polymers for the remaining part up to 100%. In some embodiments, the polymer of the multifilaments is a blend of PP and HDPE. For example, the polymer contains at least 80% PP and at least 5% HDPE. An option is between 85% and 95% PP, for example at least 90% PP, and in addition thereto HDPE up to 100%) of the polymer. The addition of acids to the polymer containing PP is useful for alkaline-sensitive bio- cides, for example Deltamethrin or fipronil. The term "alkaline sensitive" implies that alkaline environments are detrimental to the biocide, for example weakly alkaline envi- ronments with a pH as low as 7-8, or somewhat larger, such as 8-9.

The purpose of the acid is not to prevent degradation of the biocide in a solvent, as disclosed in International patent application WO 2002/07480, the purpose is also not to prevent degradation due to the heat during extrusion as disclosed in US patent No. 3,408,323, but the role of the acid is to prevent a long term degradation due to alkaline- like conditions in polypropylene after extrusion. The addition of acid in the polymer results in conditions that give higher chemical stability of the biocide, for example insecticide. In experiments, it has been verified that Deltamethrin survives the extrusion but is degraded relatively quickly after extrusion in a polypropylene matrix when not adding a suitable acid. Thus, the method where acid is included in the PP matrix, or included in the thermoplastic polymer with at least 75% pr 90% PP, together with the biocide can be used to reduce or even eliminate the detrimental chemical effect of PP on the biocide. This use prolongs the lifetime of the biocide in the PP matrix. The expression "long term" is used for a time span of more than a month, potentially more than 6 months or even more than a year.

Attractive are acids with a pKa of between 1 and 9, for example 1 to 5 or between 1.9 and 9, optionally 2 to 6 or 3 to 5.5. In the case of a polyprotic acid, this range of pKa is advantageously between 1 and 9 or between 1 and 5 or between 1.9 and 9 of pKa, optionally 2 to 6 or 3 to 5.5, which is valid for the first, most acidic proton. Alternatively, these ranges are valid for all protons of a polyprotic acid. For example, the range of between 1 and 9 or 1.9 and 9 of pKa is valid for all protons of a polyprotic acid. Carboxylic acids seem to be a good choice apart from fatty acids.

The acid in use should be relatively stable at temperatures used for extrusion. Acids like citric acid or ascorbic acid, for example L-ascorbic acid, have been experienced as fragile. Therefore, preferably, the acid for the purpose is not citric acid or ascorbic acid. The dis- acid. The disclosure of citric acid for lambda cyhalotrin in a solvent for a melt extrusion in the International patent application WO 2002/074080 and the disclosure of L-ascorbic acid as antioxidant in an insecticidal PE or PP matrix in the International patent application WO 2009/121580, indicates that the influence of acids on the insecticide in extruded PP in contrast to PE has not been fully recognised.

The acid should not have too heavy molecules, especially, if the pKa of the acid is high, because that would require a relatively large weight of acid to be added to the polypropylene in order for the effect to be satisfactory, and relatively large amounts (relatively large total weight) of acids have been found disadvantageous for the polymer system. For yarn, typically, only a small weight percentage of acid is appropriate, which sets a natural limit for the amount of acid and therefore also for the added acidity. In case that a heavy acid has a high pKa, which means a low acidity, the heavy molecular weight of the acid limits intrinsically the number of acid molecules that can be added and thus, also the overall acidic effect that can be achieved. Therefore, in a further embodiment, the mathematical product of the molecular weight and the pKa is less than 1500 or less than 1250 or less than 1000.

As a non limiting example the actual molecular weight of the acid is less than 1500 or less than 1200 or less than 1000.

Therefore, in a preferred embodiment, fatty acids have been excluded - or at least excluded to an extent such that the content of fatty acids is less than 0.1%, rather less than 0.05%, 0.02%), or 0.01%, in terms of weight of the thermoplastic polymer, in contrast to the above mentioned International patent application WO 2009/121580, where fatty acid is one of the main ingredients, preferably in the order of 1%. In this connection, fatty acids are to be understood as carboxylic acids with an even number of at least 4 carbon atoms, typically 4-28 carbon atoms, and with a long unbranched aliphatic tail that is either saturated or unsaturated. This is also the normal definition thereof.

Useful acids, alone or in combination, can be selected from Acetic Acid, Aceto-acetic Acid, Acetonedicarboxylic Acid, Acetonic Acid, Acetophenone acetylacetic Acid, Acetoxybenzoic Acid, Acetylenedicarboxylic Acid, Aconitic Acid, Aconic Acid, Acrylic Acid, Adenyl-pyrophosphoric Acid, Adipic Acid, Alchornic Acid, Aldonic Acid, Aleuritic Acid, Allocinnamic Acid, Alpha-lipoic Acid, Aminoacetic Acid, Aminoadipic Acid, Aminoazelaic Acid, Aminobenzoic Acid, Aminobenzene-sulfonic acid, Aminobutyric Acid, Amino caproic Acid, Amino cinnamic Acid, Aminoglutaric Acid, Aminoisobutylacetic Acid, Aminoisophthalic Acid, Aminoisovalerenic Acid, Aminolactic Acid, Aminononanoic Acid, Aminophenylacetic Acid, Aminophenylglyoxylic Acid, Aminopentanoic Acid, Aminophthalic Acid, Aminopimelic Acid, Aminopropionic Acid, Aminosebacic Acid, Aminosuberic Acid, Aminosuccinic Acid, Aminoterephtahlic Acid, Aminoundecanoic Acid, Aniline-p-sulfonic Acid, Anisic Acid, Anteisopalmitic Acid, Anthracene carboxylic Acid, Anthranilic Acid, Anthraquinonedisulfuric Acid, Anthraquinonesulfonic Acid, Arylglyoxylic Acids, Aspartic Acid, Auric Acid, Azelaic Acid;

Benzenesulfonic acid, Benzoic Acid, Benzoylaminovalerenic Acid, Benzoylbenzoic Acid, Benzoylbromobenzoic Acid, Benzoylbenzoic Acid, Benzylbenzoic Acid, Ben- zylidenemalonic Acid, Boric Acid, Borofluoroacetic Acid, Brassylic Acid, Bromic Acid, Bromous Acid, Bromoacetic Acid, Bromohydrocinnamic Acid, Bromomalonic Acid, Bromopropionic Acid, Bromosuccinic Acid, Bucloxic Acid, Butylnaphtalenesulfonic Acid;

Caffeic Acid, Camphoric Acid, Camphosulfonic Acid, Carbamic Acid, Carbonic Acid, Chloric Acid, Chloroacetic Acid, Chloroauric Acid, Chlorobenzoic Acid, Chlorobro- mocamphosulfonic Acid, Chlorosuccinic Acid, Chlorosulfuric Acid, Chlorous Acid, Chrysophanic Acid, Cinametic Acid, Cinchomeronic Acid, Cinnamic Acid, Citronnellic Acid, Citrosalic Acid, Coumaric Acid, Cyclohexane-diacetic Acid, Cyclohexyltridecanoic Acid, Cyclohexylundecanoic Acid, Cyclopropanic Acid ;

Decadienedioic Acid, Decatetraenedioic Acid, Decatrienedioic Acid, Decenedioic Acid, Dehydroacetic Acid, Diacetylsuccinic Acid, Diaminohexanoic Acid, Dibromo succinic Acid, Dichloroacetic Acid, Dihydrolipoic Acid, Dihydroxybenzoic Acid, Dihydroxyocta- decanoic Acid, Diisopropylbenzenesulfonic Acid, Dimethoxysuccinic Acid, Dimethyloc- tacosanedioic Acid, Dimethylsuccinic Acid, Dimethyltriacontanedioic Acid, Dioxycin- namic Acid, Diphenylacetic Acid, Diphenic Acid, Ditartric Acid, Dodecadienedioic Acid, Dodecanedioic Acid, Dodecapentaenendioic Acid, Do decatetraenedioic Acid, Dodeca- Acid, Dodecatrienedioic Acid, Dodecenedioic Acid ;

Ellagic Acid, Epoxystearic Acid, Erythorbic Acid, Ethylacetic Acid, Ethylenediamine- tetraacetic acid, Eugenic Acid, Evernic Acid ;

Ferulic Acid, Fluoric Acid, Fluorous Acid, Formaldehyde sulfoxylic Acid, Formylacetic Acid, Fumaric Acid;

Galactonic Acid, Galacturonic Acid, Gallic Acid, Gluconic Acid, Glucuronic Acid, Glutamic Acid, Glutaric Acid, Glutinic Acid, Glyceric Acid, Glycerophosphoric Acid, Glycidic Acid, Glycolic Acid, Glycolsulfonic Acid, Glycoxylic Acid, Glycuronic Acid; Heptadecadienedioic Acid, Heptadecatrienedioic Acid, Heptadecenedioic Acid, Hexa- decadienedioic Acid, Hexadecaheptaenedioic Acid, Hexadecamethylenedicarboxylic Acid, Hexadecatrienedioic Acid, Hexadecenedioic Acid, Hexadecylcitric Acid, Hexa- hydrobenzoic Acid, Hexenedioic Acid, Hexylcyclohexyloctanoic Acid, Homophthalic Acid, Homovanillic Acid, Hydantoic Acid, Hydrocinnamic Acid, Hydroxyadipic Acid, Hydroxybenzoic acid, Hydroxybenzoylbenzoic Acid, Hydroxybutyric Acid, Hydroxy- capric Acid, Hydroxycaproic Acid, Hydroxycaprylic Acid, Hydroxycinnamic Acid, Hydroxydecenoic Acid, Hydroxyglutaric Acid, Hydroxyhexadecanoic Acid, Hydroxy- heptanoic Acid, Hydroxyisophthalic Acid, Hydroxylinoleic Acid, Hydroxynaphtoic Acid, Hydroxyoctadecanoic Acid, Hydroxyoctadecenoic Acid, Hydroxypalmitic Acid, Hydroxypentanoic Acid, Hydroxyphthalic Acid, Hydroxypropionic Acid, Hydroxysali- cylic Acid, Hydroxysebacic Acid, Hydroxysuberic Acid, Hydroxyterephthalic Acid, Hypobromic Acid, Hypobromous Acid, Hypochloric Acid, Hypochlorous Acid, Hy- poiodic Acid, Hypoiodous Acid, Hyponitric Acid, Hyponitrous Acid, Hypophosphoric Acid, Hypophosphorous Acid, Hyposulfuric Acid, Hyposulfurous Acid ;

Indolebutyric Acid, Iduronic Acid, Iodic Acid, Iodous Acid, Isobutyric Acid, Isocaproic Acid, Isocaprylic Acid, Isocitric Acid, Isodibromosuccinic Acid, Isoferulic Acid, Isoheptanoic Acid, Isopalmitic Acid, Isophthalic Acid, Isosaccharinic Acid, Isovaleric Acid, Isovanillic Acid, Itaconic Acid ;

Kainic Acid, Ketoadipic Acid, Ketoazelaic Acid, Ketobutyric Acid, Ketodecenoic Acid, Ketomalonic Acid, Ketomenthylic Acid, Ketopentanoic Acid, Ketopimelic Acid, Keto- sebacic Acid, Ketosuberic Acid, Ketovalerenic Acid;

Lactic Acid, Levofolinic Acid, Levulinic Acid, Licanic Acid, Lipoic Acid; Maleic Acid, Malic Acid, Malonic Acid, Malonic Acid Alkyles, Malvalic Acid, Mandelic Acid, Meconic Acid, Mellitic Acid, Mesoxalic Acid, Methacrylic Acid, Methoxy- cyanocinnamic Acid, Methoxyhexadecenoic Acid, Methoxyoctadecanoic Acid, Meth- oxypentadecanoic Acid, Methoxypentadecenoic Acid, Methoxytetradecanoic Acid, Methoxytetradecenoic Acid, Methylacetic Acid, Methyladipic Acid, Methylbutanoic Acid, Methyleneanhydrocitric Acid, Methylenehexadecanoic Acid, Methylenehippuric Acid, Metiazinic Acid, Monochloroacetic Acid, Mucic Acid, Muconic Acid;

Napthalene-dicarboxylic Acid, Napthalene-sulfonic Acid, Naphtalenic Acid, Naphthoic Acid, Naphtosulfonic Acid, Nitrocinnamic Acid, Nitrophenylpropionic Acid, Ni- trophthalic Acid, Nitrobenzoic acid, Nonadecanedioic Acid, Nonadienedioic Acid, Nonadecadienedioic Acid, Nonatrienedioic Acid, Nonadecatrienedioic Acid;

Octadecanedicarboxylic Acid, Octadecanedioic Acid, Octadecenedioic Acid, Octadi- enedioic Acid, Octenedioic Acid, Octadecadienedioic Acid, Octatrienedioic Acid, Oc- tadecatrienedioic Acid, Octadecatetraenedioic Acid, Orthoacetyloxybenzoic Acid, Or- thoamidosalicylic Acid, Orthoaminobenzoic Acid, Orthobenzoylbenzoic Acid, Ortho- quinolinemetasulfonic Acid, Orthophenolsulfonic Acid, Oxalic Acid, Oxaloacetic Acid, Oxamic Acid, Oxodecenoic Acid, Oxoglutaric Acid, Oxononanoic Acid, Oxotridecadi- enoic Acid, Oxyvaleretic Acid;

Paraaminobenzoic Acid, Paracoumaric Acid, Parahydroxybenzoic Acid, Paraphenylenedi- acetic Acid, Parasulfamidobenzoic Acid, Paratoluenesulfinic Acid, Paratoluenesulfonic Acid, Paroxybenzoic Acid, Pentadecadienedioic Acid, Pentadecanedioic Acid, Pentadeca- trienedioic Acid, Peracetic Acid, Perbenzoic Acid, Phenoylsulfonic Acid, Phenylacetic Acid, Phenlyacrylic Acid, Phenylaminoacetic Acid, Phenylbenzoic Acid, Phenylbutanoic Acid, Phenylchloroacetic Acid, Phenyldecanoic Acid, Phenyldodecanoic Acid, Phenylei- cosanoic Acid, Phenylenediacetic Acid, Phenylglycinecarboxylic Acid, Phenylglycolic Acid, Phenylglyoxylic Acid, Phenylheptadecanoic Acid, Phenylheptanoic Acid, Phenyl- hexadecanoic Acid, Phenylhexanoic Acid, Phenylisocrotonic Acid, Phenylnonadecanoic Acid, Phenylnonanoic Acid, Phenyloctadecanoic Acid, Phenyloctanoic Acid, Phenylpen- tadecanoic Acid, Phenylpentanoic Acid, Phenylpropanoic Acid, Phenylpropiolic Acid, Phenylsulfurous Acid, Phenyltetradecanoic Acid, Phenyltridecanoic Acid, Phenylunde- canoic Acid, Phthalic Acid, Phtalamic Acid, Phtalonic Acid, Phtalylacetic Acid, Phytanic Acid, Phytomonic Acid, Picolinic Acid, Pimelic Acid, Piperic Acid, Piperonylic Acid, Pristanic Acid, Propionic Acid, Protocatechuic Acid, Pyrogallic Acid, Pyrrolecarboxylic catechuic Acid, Pyrogallic Acid, Pyrrolecarboxylic Acid, Pyrrolidinecarboxylic Acid, Pyruvic Acid;

Quinic Acid;

Ribonic Acid, Ricinelaidic Acid, Ricinic Acid, Ricinoleic Acid;

Saccharic Acid, Salicylic Acid, Santonic Acid, Sebacic Acid, Sialic Acid, Sinapic Acid, Suberic Acid, Succinic Acid, Sulfamidobenzoic Acid, Sulfanilic Acid;

Tartaric Acid, Tartronic Acid, Terephthalic Acid, Tert-butylbenzoic Acid, Tetracemic Acid, Tetradecadienedioic Acid, Tetradecahexaenendioic Acid, Tetradecanedioic Acid, Tetradecatrienedioic Acid, Tetradecenedioic Acid, Tetrahydronaphthalenecarboxylic Acid, Tetraoxyhexahydrobenzoic Acid, Thapsic Acid, Thyropropic Acid, Tiglic Acid, Toluic Acid, Traumatic Acid, Tridecadienedioic Acid, Tridecatrienedioic Acid, Trihy- droxybenzenetricarboxylic Acid, Trihydroxybenzoic Acid, Trihydroxystearic Acid, Trimesic Acid, Trimethoxybenzoic Acid, Trimethylacetic Acid, Trimethylenecarboxylic Acid, Trioxybenzoic Acid, Tropic Acid;

Undecandicarboxylic Acid, Uronic Acid, Uvitic Acid, Undecadienedioic Acid, Undeca- trienedioic Acid;

Valerenic Acid, Vanillic Acid, Veratric Acid, Vernolic Acid;

The above acids are, especially, suited in combination with Deltamethrin in PP or Del- tamethrin in a thermoplastic polymer with at least 75% PP, for example at least 90% or 95% PP by weight of the polymer. For example, the thermoplastic polymer of the extruded or molded matrix is a blend of polymers and comprises at least 75% polypropylene homopolymer, for example at least 90% or at least 95% polypropylene homopolymer, or 100% polypropylene by weight of the total thermoplastic polymer of the matrix. Optionally, the thermoplastic polymer of the extruded or molded matrix is a blend of polymers only being homopolymers.

In this case, the combination of each of the acids is as example, especially, advantageous against mosquitoes, specifically on mosquito nets.

An advantageous content of such an acid or mixture of acids is 1-30 g/kg PP, more optionally 1-15 g/kg, for example 1-8 g/kg, such as l-3g/kg or 3-5 g/kg. A preferred option for the biocide is an insecticide, for example a pyrethroid. The method has been developed especially for Deltamethrin, although it applies equally well for other alkaline-sensitive biocides/insecticides. For example, Abamectin, Chlorfenapyr, Imidacloprid, and Pyriproxyfen are reported to have acidic pH as optimum. In a further embodiment, the biocide/insecticide is Abamectin, Chlorfenapyr, Imidacloprid, or Pyriproxyfen. Dinotefuran has an optimum pH extending to pH=8 into the weakly basic pH region. In a further embodiment, the biocide is Dinotefuran.

In an even further embodiment, the biocide is selected from Abamectin, Acephate, Acequinocyl, Acetamiprid, Azadirachtin, Bifenazate, Bifenthrin, Buprofezin, Chlorpyri- fos, Clofentezine, Cyfluthrin, Cyromazine, Diflubenzuron, Etoxazole, Fenpropathrin, Fenpyroximate, Flonicamid, Fluvalinate, Imidacloprid, Methiocarb, Novaluron, Pyriproxyfen, Pymetrozine, Pyridaben, Spinosad, Spiromesifen, and Thiamethoxan or combinations thereof. According to the disclosure by Dr. Raymond A.Cloyd on the Inter- net page www.oardc.ohio-state.edu/floriculture/images/ FloriBytesl009-pest.pdf these biocides are alkaline sensitive. Having regard to the fact that some are more sensitive than others, in a further embodiment, the biocide is selected from Abamectin, Acephate, Acequinocyl, Azadirachtin, Buprofezin, Clofentezine, Cyromazine, Etoxazole, Fenpropathrin, Fenpyroximate, Flonicamid, Fluvalinate, Imidacloprid, Methiocarb, Pyriproxyfen, Pyridaben, Spinosad, and Spiromesifen, or combinations thereof, which all have an optimal water pH of at most 8.

Advantageously, the method comprises blending 1-20 g Deltamethrin and 1-30 g acid per kg of polypropylene, optionally 1-15 or l-5g acid per kg PP, extruding the blend into a yarns and weaving the yarns into a fabric, especially a mosquito net. When having regard to the fact that the insecticidal effect should be long lasting, a yarn having 5-10 filaments is preferred.

For Deltamethrin (DM), an advantageous content in an article, especially in a yarn for LLIN, is 1-20 g per kg PP or 1-7 g/kg or 1-4 g/kg or 1.6-2.0 g/kg, such as 1.8 g/kg. For example, the following combinations are proposed with the insecticide Deltamethrin: Insecticide in g/k Acid in g/kg PP

PP

1-20 1-30

1-20 1-8

1-20 1-3

1-20 3-5

1-7 1-30

1-7 1-8

1-7 1-3

1-7 3-5

1-4 1-30

1-4 1-8

1-4 1-3

1-4 3-5

1.6-2.0 1-30

1.6-2.0 1-8

1.6-2.0 1-3

1.6-2.0 3-5

Alternatively, the insecticide concentration and acid concentration in the above table is used also for other insecticides. For example, in the table above, DM is substituted by with Abamectin, Chlorfenapyr, Dinotefuran, Fipronil, Imidacloprid, or Pyriproxyfen.

In insecticidal fabrics, especially insect nets, an advantageous concentration of Del- tamethrin is 40-500 mg/m². On coated mosquito nets, the concentration for bednets on the market is typically 40 to 75 mg/m² with a target value around 55 mg/m². In nets or fabrics where Deltamethrin is incorporated, for example for crop protection or in greenhouses, the concentration is typically higher, for example up to 500 mg/m².

In order to keep conditions in the matrix suitable for Deltamethrin stability, the acid should not migrate or at least migrate less than the insecticide. For this reason, it is beneficial if the acid is solid at normal temperatures for use in LLIN, which is for all tempera- temperatures below 50°C or at least below 70°C, for example, solid at all temperatures below 24 degrees.

As yams according to the invention are extruded, the acid should be stable and not disintegrate at the extrusion temperature, as already mentioned above. At least 50%, optionally at least 70% or at least 90%, of the acid should stay intact until the cooling and solidification of the polymer after the extrusion process.

Other beneficial ingredients for a multifilament yarn, for example a multifilament PP yam, according to the above, include synergists, for example piperonyl butoxide, UV protecting agents, preservatives, detergents, fillers, impact modifiers, anti-fogging agents, blowing agents, clarifiers, nucleating agents, coupling agents, conductivity-enhancing agents to prevent static electricity, stabilizers such as anti-oxidants, carbon and oxygen radical scavengers and peroxide decomposing agents and the like, flame retardants, mould release agents, optical brighteners, spreading agents, antiblocking agents, anti- migrating agents, migration promoters, foam-forming agents, anti-soiling agents, antifouling agents, thickeners, wetting agents, plasticizers adhesive or anti-adhesive agents, fragrance, pigments, and dyestuffs. For long lasting insecticidal nets, a yam with the following combined properties has been found to be a good candidate. The yam has a weight of 75 to 150 Denier, optionally 100 Denier, and 3 to 12 or 5 to 9 identical polypropylene filament, for example 6, 7, or 8, into which between 1 and 20 g Deltamethrin per kg polypropylene has been incorporated. The polypropylene also contains an acid, optionally 2-8 g/kg of an acid or 3-5 g/kg, such as 4 g/kg, for changing the matrix into conditions suitable for Deltamethrin. For example, the article comprises no fatty acid or at least less than 0.01 g/kg of fatty acid by weight of the polymer.

A yam according to the invention can be produced by assembling 3-12 or 5-9, or 6, 7, or 8 filaments after extrusion and optional stretching of the filaments as monofilaments. Typically, extruded filaments are stretched by a factor of 3-8 or 3-5 immediately after extrusion. Alternatively, the number of filaments may be extruded simultaneously in a single extruder and then assembled into a single multifilament yarn, for example in a pro- production line immediately following the extrusion and optional stretching of the filaments. The different ingredients are incorporated in the molten resin prior to extrusion in order to get a proper distribution of the ingredients in the polymer matrix. The yarn is especially useful for a long lasting insecticidal net, such as bednets, with polymer yarns containing Deltamethrin. However, other biocides in connection with the invention in general are insecticides including but not limited to pyrethroids, or- ganophosphates, neonicotinoids, pyrroles, pyrazoles, carbamates, cyclodienes, or- ganochlorines, nereistoxin analogues, diamides, or combinations of at least two of these. A large number of possible biocides/insecticides including other pyrethroids are listed in greater detail in Bayer's patent application WO200/012887 together with other suitable ingredients.

Also, other applications than bed nets are possible, including nets or fabrics used in agriculture, such as fences, greenhouse nets, or crop enclosures, especially for fruits or vegetables hanging on trees or bushes; examples are cocoa pods or banana. Further examples are bedclothes, mattresses, pillows, duvets, cushions, curtains, wall coverings, carpeting and window, cupboard and door screens, geotextiles, tents, inner soles of shoes, garments, such as socks, trousers, shirts, uniforms, horse blankets, covering in agriculture and viniculture; fabrics or nettings for packages, wrapping sacks; containers for food, seeds and feed; construction materials, furniture.

Further special applications in connection with the invention are as,

- fencing, for example as disclosed in WO03/003827,

- pesticidal blanket, for example as disclosed in WO03/055307,

- protective cover for food and water storage containers, for example as disclosed in WO03/090532,

- air cleaning canopy, for example as disclosed in WO2006/024304;

- fabrics or nets for covering the space between the upper edge of a wall and the under- side of the roof in a hut, for example as explained in more detail in WO2009/059607.

Although, the primary purpose of the invention is to protect against mosquitoes, it also includes control and/or to combat a variety of pests, such as ticks, cockroaches, bed bugs, mites, fleas, lice, leeches, houseflies, mosquitoes, termites, ants, moths, spiders, grasshoppers, crickets, silverfish, and other flying and crawling insects. Furthermore, the biocidal aspect also includes use as antimicrobial action, for example against bacteria and virus.

The weight content in the foregoing expresses the weight in grams of the active ingredient relative to the weight in kg of the polymer.

The term "between" for limits of any above mentioned interval, optionally, also includes endpoints of the intervals. For example, the expression "between 2 and 4 g/kg", optionally, also include the endpoints of 2 and 4 g/kg.

All percentages in the description and claims are given by weight of the polymer without other ingredients

Claims

A multifilament yarn having a number of filaments made of a thermoplastic polymer into which a biocide or a group of biocides is incorporated, characterised in that the number of filaments is only 3 to 12.

A multifilament yarn according to claim 1, wherein the filaments of the multifilament yarn are twisted.

A multifilament yarn according to claim 1 or 2, wherein the number of filaments is 5 to 9.

A multifilament yarn according to any preceding claim, wherein the filaments each have a weight of 12 to 17 denier.

A multifilament yarn according to any preceding claim, wherein the multifilament yarn has a weight of between 75 and 150 denier.

A multifilament yarn according to any preceding claim, wherein the biocide or group of biocides is migratably incorporated into the thermoplastic polymer and distributed throughout the filaments for gradual migration from inside the filament to the outer surface of it.

A multifilament yarn according to any preceding claim, wherein the biocide is an organic biocide or wherein the wherein the group of biocides comprises an organic biocide.

A multifilament yarn according to any preceding claim, wherein the biocide is an insecticide or wherein the wherein the group of biocides comprises at least one insecticide.

9. A method according to claim 8, wherein the insecticide is Abamectin, Chlor- fenapyr, Deltamethrin, Dinotefuran, Fipronil, Imidacloprid, or Pyriproxyfen or wherein the wherein the group of biocides comprises Abamectin, Chlorfenapyr, Dinotefuran, Fipronil, Imidacloprid, or Pyriproxyfen.

10. A multifilament yarn according to claim 9, wherein the concentration of Del- tamethrin is 1-20 g Deltamethrin per kg thermoplastic polymer.

11. A multifilament yarn according to claim 9, wherein the concentration of Deltamethrin is 1-7 g Deltamethrin per kg thermoplastic polymer.

12. A multifilament yarn according to any preceding claim, wherein the thermoplastic polymer is comprises at least 75% polypropylene.

13. A multifilament yarn according to any preceding claim, wherein the thermoplastic polymer is polypropylene.

14. A multifilament yarn according to any preceding claim, wherein the filaments are identical.

15. A multifilament yarn according to any one of the claims 1-13, wherein at least one of the filaments in the multifilament yarn contains a first biocide and at least one of the other filaments in the multifilament yarn does not contain the first biocide but contain a second biocide different from the first biocide.

16. A multifilament yarn according claim 15, wherein at least one filament of the multifilament yarn comprises Dinotefuran or Fipronil or both but not PBO or Deltamethrin and at least one other filament in the same multifilament yarn comprises PBO or Deltamethrin or both but not Dinotefuran or Fipronil.

17. A multifilament yarn according to any preceding claim, wherein the multifilament yarn is part of a mosquito net.

18. A multifilament yarn according to any preceding claims, wherein the multifilament yarn comprises a thermoplastic polymer matrix with a biocide or group of biocides migratably incorporated and distributed throughout the matrix for gradual migration of the biocide or group of biocides from inside the matrix to a surface of the matrix, wherein the thermoplastic polymer of the matrix comprises at least

75% of polypropylene by weight of the thermoplastic polymer, wherein also an acid is incorporated and distributed throughout the matrix.

A multifilament yarn according to claim 18, wherein, the acid is at least on of the group comprising:

Acetic Acid, Aceto-acetic Acid, Acetonedicarboxylic Acid, Acetonic Acid, Acetophenone acetylacetic Acid, Acetoxybenzoic Acid, Acetylenedicarboxylic Acid, Aconitic Acid, Aconic Acid, Acrylic Acid, Adenyl-pyrophosphoric Acid, Adipic Acid, Alchornic Acid, Aldonic Acid, Aleuritic Acid, Allocinnamic Acid, Alpha- lipoic Acid, Aminoacetic Acid, Aminoadipic Acid, Aminoazelaic Acid, Aminobenzoic Acid, Aminobenzene-sulfonic acid, Aminobutyric Acid, Amino caproic Acid, Amino cinnamic Acid, Aminoglutaric Acid, Aminoisobutylacetic Acid, Aminoisophthalic Acid, Aminoisovalerenic Acid, Aminolactic Acid, Aminononanoic Acid, Aminophenylacetic Acid, Aminophenylglyoxylic Acid, Aminopentanoic Acid, Aminophthalic Acid, Aminopimelic Acid, Aminopropionic Acid, Aminosebacic Acid, Aminosuberic Acid, Aminosuccinic Acid, Aminoterephtahlic Acid, Aminoundecanoic Acid, Aniline-p-sulfonic Acid, Anisic Acid, Anteisopalmitic Acid, Anthracene carboxylic Acid, Anthranilic Acid, Anthraquinonedisulfuric Acid, Anthraquinonesulfonic Acid, Arylglyoxylic Acids, Aspartic Acid, Auric Acid, Azelaic Acid;

Benzenesulfonic acid, Benzoic Acid, Benzoylaminovalerenic Acid, Benzoylbenzoic Acid, Benzoylbromobenzoic Acid, Benzoylbenzoic Acid, Benzylbenzoic Acid, Ben- zylidenemalonic Acid, Boric Acid, Borofluoroacetic Acid, Brassylic Acid, Bromic Acid, Bromous Acid, Bromoacetic Acid, Bromohydrocinnamic Acid, Bromomalonic Acid, Bromopropionic Acid, Bromosuccinic Acid, Bucloxic Acid, Butylnaphtalenesulfonic Acid; Caffeic Acid, Camphoric Acid, Camphosulfonic Acid, Carbamic Acid, Carbonic Acid, Chloric Acid, Chloroacetic Acid, Chloroauric Acid, Chlorobenzoic Acid, Chlorobro- mo camphosulfonic Acid, Chlorosuccinic Acid, Chlorosulfuric Acid, Chlorous Acid, Chrysophanic Acid, Cinametic Acid, Cinchomeronic Acid, Cinnamic Acid, Citronnellic Acid, Citrosalic Acid, Coumaric Acid, Cyclohexane-diacetic Acid, Cyclohexyltridecanoic Acid, Cyclohexylundecanoic Acid, Cyclopropanic Acid ;

Decadienedioic Acid, Decatetraenedioic Acid, Decatrienedioic Acid, Decenedioic Acid, Dehydroacetic Acid, Diacetylsuccinic Acid, Diaminohexanoic Acid, Dibromo succinic Acid, Dichloroacetic Acid, Dihydrolipoic Acid, Dihydroxybenzoic Acid, Dihy- droxyoctadecanoic Acid, Diisopropylbenzenesulfonic Acid, Dimethoxysuccinic Acid, Dimethyloctacosanedioic Acid, Dimethylsuccinic Acid, Dimethyltriacontanedioic Acid, Dioxycinnamic Acid, Diphenylacetic Acid, Diphenic Acid, Ditartric Acid, Dodecadi- enedioic Acid, Dodecanedioic Acid, Dodecapentaenendioic Acid, Dodecatetraenedioic Acid, Dodecatrienedioic Acid, Dodecenedioic Acid ;

Galactonic Acid, Galacturonic Acid, Gallic Acid, Gluconic Acid, Glucuronic Acid, Glutamic Acid, Glutaric Acid, Glutinic Acid, Glyceric Acid, Glycerophosphoric Acid, Glycidic Acid, Glycolic Acid, Glycolsulfonic Acid, Glycoxylic Acid, Glycuronic Acid; Heptadecadienedioic Acid, Heptadecatrienedioic Acid, Heptadecenedioic Acid, Hexade- cadienedioic Acid, Hexadecaheptaenedioic Acid, Hexadecamethylenedicarboxylic Acid, Hexadecatrienedioic Acid, Hexadecenedioic Acid, Hexadecylcitric Acid, Hexahydroben- zoic Acid, Hexenedioic Acid, Hexylcyclohexyloctanoic Acid, Homophthalic Acid, Ho- movanillic Acid, Hydantoic Acid, Hydrocinnamic Acid, Hydroxyadipic Acid, Hydroxy- benzoic acid, Hydroxybenzoylbenzoic Acid, Hydroxybutyric Acid, Hydroxycapric Acid, Hydroxycaproic Acid, Hydroxycaprylic Acid, Hydroxycinnamic Acid, Hydroxydecenoic Acid, Hydroxyglutaric Acid, Hydroxyhexadecanoic Acid, Hydroxyheptanoic Acid, Hy- droxyisophthalic Acid, Hydroxylinoleic Acid, Hydroxynaphtoic Acid, Hydroxyocta- decanoic Acid, Hydroxyoctadecenoic Acid, Hydroxypalmitic Acid, Hydroxypentanoic Acid, Hydroxyphthalic Acid, Hydroxypropionic Acid, Hydroxysalicylic Acid, Hydroxyse- bacic Acid, Hydroxysuberic Acid, Hydroxyterephthalic Acid, Hypobromic Acid, Hypo- Hypobromic Acid, Hypobromous Acid, Hypochloric Acid, Hypochlorous Acid, Hy- poiodic Acid, Hypoiodous Acid, Hyponitric Acid, Hyponitrous Acid, Hypophosphoric Acid, Hypophosphorous Acid, Hyposulfuric Acid, Hyposulfurous Acid ;

Lactic Acid, Levofolinic Acid, Levulinic Acid, Licanic Acid, Lipoic Acid;

Maleic Acid, Malic Acid, Malonic Acid, Malonic Acid Alkyles, Malvalic Acid, Mandelic Acid, Meconic Acid, Mellitic Acid, Mesoxalic Acid, Methacrylic Acid, Methoxy- cyanocinnamic Acid, Methoxyhexadecenoic Acid, Methoxyoctadecanoic Acid, Meth- oxypentadecanoic Acid, Methoxypentadecenoic Acid, Methoxytetradecanoic Acid, Methoxytetradecenoic Acid, Methylacetic Acid, Methyladipic Acid, Methylbutanoic Acid, Methyleneanhydrocitric Acid, Methylenehexadecanoic Acid, Methylenehippuric Acid, Metiazinic Acid, Monochloroacetic Acid, Mucic Acid, Muconic Acid;

Paraaminobenzoic Acid, Paracoumaric Acid, Parahydroxybenzoic Acid, Paraphenylenedi- acetic Acid, Parasulfamidobenzoic Acid, Paratoluenesulfinic Acid, Paratoluenesulfonic Acid, Paroxybenzoic Acid, Pentadecadienedioic Acid, Pentadecanedioic Acid, Pentadeca- trienedioic Acid, Peracetic Acid, Perbenzoic Acid, Phenoylsulfonic Acid, Phenylacetic sulfonic Acid, Phenylacetic Acid, Phenlyacrylic Acid, Phenylaminoacetic Acid, Phenyl- benzoic Acid, Phenylbutanoic Acid, Phenylchloroacetic Acid, Phenyldecanoic Acid, Phenyldodecanoic Acid, Phenyleicosanoic Acid, Phenylenediacetic Acid, Phenylgly- cinecarboxylic Acid, Phenylgly colic Acid, Phenylglyoxylic Acid, Phenylheptadecanoic Acid, Phenylheptanoic Acid, Phenylhexadecanoic Acid, Phenylhexanoic Acid, Phenyli- socrotonic Acid, Phenylnonadecanoic Acid, Phenylnonanoic Acid, Phenyloctadecanoic Acid, Phenyloctanoic Acid, Phenylpentadecanoic Acid, Phenylpentanoic Acid, Phenyl- propanoic Acid, Phenylpropiolic Acid, Phenylsulfurous Acid, Phenyltetradecanoic Acid, Phenyltridecanoic Acid, Phenylundecanoic Acid, Phthalic Acid, Phtalamic Acid, Phtalonic Acid, Phtalylacetic Acid, Phytanic Acid, Phytomonic Acid, Picolinic Acid, Pimelic Acid, Piperic Acid, Piperonylic Acid, Pristanic Acid, Propionic Acid, Protocatechuic Acid, Pyrogallic Acid, Pyrrolecarboxylic Acid, Pyrrolidinecarboxylic Acid, Pyruvic Acid;

Quinic Acid;

Ribonic Acid, Ricinelaidic Acid, Ricinic Acid, Ricinoleic Acid;

Valerenic Acid, Vanillic Acid, Veratric Acid, Vernolic Acid; 20. A multifilament yarn according to claim 18 or 19, wherein the acid has a pKa of 1 to 9.

21. A multifilament yarn according to claim 18 or 19, wherein the acid has a pKa of 1.9 to 9.

22. A multifilament yarn according to claim 18 or 19, wherein the acid has a pKa of 2 to 6.

23. A multifilament yarn according to anyone of the claims 18-22, wherein the molecular weight of the acid is less than 1500.

24. A multifilament yarn according to claims 23, wherein the molecular weight of the acid is less than 1200.

25. A multifilament yarn according to anyone of the claims 18-24, wherein the mathematical product of a pKa of the acid and the molecular weight of the acid is less than 1500.

26. A multifilament yarn according to claims 25, wherein the mathematical product of a pKa of the acid and the molecular weight of the acid is less than 1000.

27. A multifilament yarn according to anyone of the claims 18-26, wherein the acid concentration is 1-30 g acid per kg of the thermoplastic polymer.

28. A multifilament yarn according to claim 27, wherein the acid concentration is 1-15 g acid per kg of the thermoplastic polymer.

29. A multifilament yarn according to claim 27, wherein the acid concentration is 1-5 g acid per kg of the thermoplastic polymer.

30. A multifilament yarn according to any one of the claims 18-29, wherein the yarn is a multifilament yarn with a weight of 75-150 Denier and 3-12 identical thermoplastic filaments into which 1-20 g Deltamethrin and 1-30 g acid per kg thermoplastic polymer have been incorporated, and wherein the article comprises less than 0.01 g/kg of fatty acid.

31. A multifilament yarn according to any one of the claims 18-30, wherein the thermoplastic polymer comprises at least 90% polypropylene by weight of the thermoplastic polymer.

32. A multifilament yarn according to any one of the claims 18-30, wherein the thermoplastic polymer is a blend of polymers and comprises at least 75% polypropylene homopolymer. 33. A multifilament yarn according to claim 32, wherein the thermoplastic polymer is a blend of polymers and comprises at least 90% polypropylene homopolymer.

34. A multifilament yarn according to any one of the claims 18-33, wherein the polymer also comprises 5%-10% HDPE.

35. A multifilament yarn according to any one of the claims 18-30, wherein the thermoplastic polymer is polypropylene.