WO2011124227A1

WO2011124227A1 - Biocidal acid-adjusted polymer with polypropylene

Info

Publication number: WO2011124227A1
Application number: PCT/DK2011/050115
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: TW201210478A

Abstract

A method for providing long term stability for an alkaline-sensitive biocide in a polypropylene product by incorporating the biocide, for example Deltamethrin, together with an acid in a polymer matrix with polypropylene; an article comprising a thermoplastic polypropylene polymer matrix with a biocide and an acid distributed throughout the polymer matrix; and the article being a multifilament yarn from which a mosquito net can be made.

Description

Biocidal acid-adjusted polymer with polypropylene

Field of the Invention

The present invention relates to a polypropylene 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 migratably incorporated in 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.

Whereas use of PE as a material in the market of LLIN is a success, polypropylene (PP) has not experienced the same attraction. One of the reasons that PP has not found way to the market for LLIN is that PP yarns with Deltamethrin seem not to have a sufficient in- ficient insecticidal function as expected. Also, PP does not provide as stabilizing a matrix as PE. However, as Deltamethrin is the most used insecticide for long lasting insecticidal nets, and the efficiency of a Deltamethrin-containing yam directly reflects the popularity of such kind of yams, PP is not so attractive for such articles, although PP has some advantages, for example a broad variety of resins with various melt flow indices, processing properties and mechanical properties.

It would therefore be desirable to provide an improved insecticidal PP yarn, especially for mosquito nets, with high and long lasting insecticidal efficiency.

Theoretical attempts for LLIN with PP yarn are found in the literature, for example as disclosed in Basell's WO2008/141915, South African patent application ZA2005/09810 by Moznet CC, or in CN1468984/CN1180139 by Shanghai Petro-Chem Co Ltd. Further, international patent application WO 2009/121580 by Bayer discloses extruded insecticidal PE or PP with an additive, for example a fatty acid and/or an antioxidant, such as L- ascorbic acid. The extruded polymer can be used for bednets. An example is given for extruded insecticidal PP foils with oleic acid as additive. The disclosure is directed towards PE as well as PP, and does not differentiate with respect to the behaviour of these two polyolefms with respect to the lifetime of the insecticide, such as Deltamethrin. Thus, the unique problem with PP relatively to PE for Deltamethrin seems not to have been recognised.

GB1045456A discloses a method for the production of a synthetic thermoplastic resin comprising an insecticide, an acid additive, and a PE or PP matrix. A blend of active ingredient and acid is added to the heated thermoplastic material. The pesticide is a carbamate and the preferred acid is boric acid or phosphoric acid. The reason for the addition of acid is thermal stability of the insecticide during extrusion.

EP0548940 discloses a slow release solid formulation for pyrethroids containing an ammonium cation and a stabilizing acid that keeps the pH in the range 1-9.5. The solid matrix is represented by silicates of different origin. The acid is inorganic or organic, for example by containing carboxylic groups. Boric acid or salicylic acid is used in the examples. Fatty acids are also included as binders in paraffin matrices as disclosed in International patent application WO 2002/074080. In this disclosure, the isomerisation of lambda cyhalotrin due to high pH in solvents is discussed, why it is proposed to use citric acid in the solvent in connection with a polymer melt in general, for example comprising polyethylene glycol. Citric acid is also disclosed as a heat stabilizer in US patent No. 3,408,323 for carbamates.

It is generally known that some biocides/insecticides are sensitive to even weak alkalinity. For example, the optimum water pH for certain insecticides and miticides is disclosed by Dr. Raymond A.Cloyd from Kansas State University on the Internet page www.oardc.ohio-state.edu/floriculture/images/FloriBytesl009-pest.pdf The table is reproduced below.

As it appears from the table above, there is a clear difference between various insecticides with respect to pH sensitivity. But it seems that there is no en-bloc rule for optimum pH for pyrethroids. For pyrethroid Fenpropathrin, an optimum pH is in the range of 5.5-6.5, which is clearly acidic, whereas an alkaline pH of up to 9 is optimum for other pyrethroids, such as Bifenthrin and Cyfluthin. Especially, having a pH of up to 9.5 as disclosed in the above EP0648940 for pyrethroids in general seems to be in contradiction with optimized pH for pyrethroids when comparing with the table above, because a pH of 9.5 would cause degeneration of Fenpropathrin due to alkalinity.

Actually, also Deltamethrin is known to be pH sensitive. Especially, Deltamethrin is known to have a reduced lifetime in alkaline environments as compared to neutral or weakly acidic environments. This is why acetic acid has been proposed for acidification in water suspensions of polymers, for example as disclosed in International patent application WO 01/037622. However, the data sheet D-6153MSDS of Deltamethrin as provided by LC Laboratories on the Internet page www.oardc.ohio- state.edu/floriculture/images/FloriBytesl009-pest.pdf states that acids and bases should be avoided in connection with Deltamethrin. Thus, the use of acids in connection with Deltamethrin is not a clarified issue.

PP is not an aqueous system, and if Deltamethrin is added as a powder to molten PP without any other solvents, the pH discussion seems not to make sense for such a system.

Object of the Invention

It is therefore the purpose of the invention to provide polypropylene with improved properties with respect to biocides, especially Deltamethrin. It is also the purpose to provide an improved polypropylene yarn, especially for insecticidal mosquito nets. Description of the Invention

As has been recognised by the inventor as part of the invention is the fact that Deltame- thrin is degraded when incorporated in PP, where the degradation appears after the extrusion and is therefore not related to extrusion process at high temperature. As it appears from above, the problem with insecticide degradation in PP after the extrusion, especially degradation of Deltamethrin, seems not to have been recognised or solved. The prior art focuses on the extrusion process and tries to solve degradation due to the high extrusion temperatures by using various additives.

Improved properties with respect to reduced degradation of biocides are achieved with a method for providing stability, especially long term stability, for a biocide in polypropylene as describe in the following. In this method, 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 polypropylene batch. Such a 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 pure polypropylene batch, before melt extrusion or molding. Alternatively, the blend is directly melt extruded or molded into a matrix. Thereby, the biocide and the acid are distributed throughout the theremoplastic matrix.

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 biocides can be used instead of a single biocide.

The addition of acids for preventing degradation of the biocide is useful in thermoplastic matrices where the content of PP is dominating. Therefore, in practice, the thermoplastic polymer of the extruded or molded matrix comprises at least 75% polypropylene, for example at least 80%, at least 90%>, at least 95%, or 100% polypropylene by weight of the total thermoplastic polymer of the matrix. The weight of the thermoplastic polymer of tic 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 polyolefms, especially polyethylene, including Linear Low Density PolyEthylene (LLDPE), Low Density Polyethylene (LDPE), Medium Density Polyethylene (MDEPE), 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.

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. Such blends are good for biocides like Deltamethrin, Fipronil, and Dinotefuran.

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 80%), 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 ho- mopolymers.

The method is useful for alkaline-sensitive biocides, for example Deltamethrin or fipronil. The term "alkaline-sensitive" implies that alkaline environments are detrimental to the biocide, for example weakly alkaline environments with a pH as low as 7-8, or somewhat larger, such as 8-9. 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.

When the invention is used in connection with insecticidal fabrics that should be prevented from moth attacks, the incorporated biocide need not migrate from inside the polymer matrix of the yarn 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. For this reason, the incorporated biocide is migratably incorporated in the polymer matrix and provided on the surface of the matrix by gradual migration of the biocide from inside the matrix to a surface of the matrix.

Coming back to the observed alkaline sensitivity, closer study of the problem by the applicant has revealed that a PP matrix itself, for example the commercial Ziegler-Natta type or the Metallocene type, has a detrimental effect on Deltamethrin or other alkaline- sensitive biocides when incorporated in the polypropylene. The detrimental effect is analogous to an alkaline effect on Deltamethrin when in water-based environments. This is surprising when having regard to the hydrophobic nature of PP. Especially, 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 can be prolonged in PP by adding acids into the polymer matrix before or during extrusion, which is a simple way to improve the biocidal capabilities of PP remarkably.

The purpose of the acid is not to prevent degradation of the biocide in a solvent, as disclosed in the above mentioned International patent application WO 2002/074080; 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 ene 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% or 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, 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.

Thus in one embodiment, the above purpose is achieved with a method for providing stability for a biocide in polypropylene, the method comprising

- providing a thermoplastic polymer for extrusion,

- providing a blend by adding acid and a biocide or group of biocides to the thermoplastic polymer ,

- melt extruding or molding the blend into a matrix with a distribution of biocide and acid throughout the matrix,

- wherein the thermoplastic polymer of the matrix comprises at least 75% polypropylene, wherein the acid has a pKa of 1 to 9, for example 1 to 5 or between 1.9 and 9, optionally 2 to 6 or 3 to 5.5. 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 L-ascorbic acid. The disclosure of citric acid for lambda cyhalotrin in a solvent for a melt extrusion in the in the above mentioned International patent application WO 2002/074080 and the disclosure of L-ascorbic acid as antioxidant in an insecticidal PE or PP matrix in the above mentioned 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 poses 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.

In one embodiment, the above purpose is achieved with a method for providing stability for a biocide in polypropylene, the method comprising

- providing a thermoplastic polymer for extrusion,

- wherein the thermoplastic polymer of the matrix comprises at least 75% polypropylene, wherein the mathematical product of the molecular weight of the acid and its pKa is less than 1500, for example less than 1250 or less than 1000. Optionally, the pKa of the acid is 1 to 9, for example 1 to 5 or between 1.9 and 9, optionally 2 to 6 or 3 to 5.5. 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, Arylglyoxyhc 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, 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, Do decatetraenedioic 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, 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 ;

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 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, Phenylglycolic 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;

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; As already mentioned above, an 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. Abamectin, Chlor- fenapyr, Imidacloprid, and Pyriproxyfen are reported to have acidic pH as optimum. In a 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 aforementioned Dr. Raymond A.Cloyd on the Internet 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.

The following shows specifically advantageous examples with Deltamethrin (DM)

It should be mentioned that Fipronil is alkaline sensitive, as well. Thus, Examples numbers 417-832 are identical to the above examples apart from DM being substituted by Fipronil. Examples numbers 833-1248 are identical to the above examples apart from DM being substituted by Abamectin. Examples numbers 1249-1664 are identical to the above examples apart from DM being substituted by Chlorfenapyr. Examples numbers 1665- 2080 are identical to the above examples apart from DM being substituted by Imidacloprid. Examples numbers 2081-2496 are identical to the above examples apart from DM being substituted by Pyriproxyfen. Examples numbers 2497-2912 are identical to the above examples apart from DM being substituted by Dinotefuran The examples are especially advantageous against mosquitoes, specifically on mosquito nets. They are also advantageous for greenhouse nets or fences around agricultural areas. Also for other fabrics or sheets, including tarpaulins, the examples are advantageous.

An advantageous content of such an acid or mixture of acids is 1-30 g/kg PP, optionally 1-15 g/kg, for example 1-8 g/kg, such as 1-3 g/kg or 3-5 g/kg.

The method is suitable for production of thin sheets or fibres by extrusion. Especially, the method is suitable for yarn to be used for fabrics and textiles, for example long lasting insecticidal nets. But, it may be used for other articles as well, for example tarpaulins as disclosed in International patent application WO03/63587 by Vestergaard Frandsen.

Advantageously, the method comprises blending 1-20 g Deltamethrin and 1-30 g acid per kg of polypropylene, optionally 1-15 or 1-5 g acid per kg PP, extruding the blend into a yarns and weaving the yarns into a fabric, especially a mosquito net. The yarns may be monofilaments or multifilaments. For Deltamethrin, an advantageous content in an article, especially in a yarn for LLIN, is 1-20 g per kg PP, optionally 1-7 g/kg or 1-4 g/kg, for example from 1.6-2.0 g/kg, such as 1.8 g/kg. For example, the following combinations are proposed with the insecticide Deltamethrin:

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 temperatures below 50°C or at least below 70°C, for example, solid at all temperatures below 24 degrees.

As articles according to the invention are molded or extruded, the acid should be stable and not disintegrate at the extrusion or molding 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 or molding process. Other beneficial ingredients for an insecticidal PP article 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.

Especially, an article in the form of an insecticidal PP yarn for LLIN has great interest and requires some additional explanation.

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 disclosed in US 5,028,471 has a weight of 4080 denier, which is far too thick and therefore useless for mosquito nets. 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 is generally unsuitable in polyolefins, 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.

However, it has now surprisingly found that that, on the one hand, a textile-like feeling can be achieved for a PP yarn having a low number of only 3-12 filaments, for example 5 to 9 filaments, 6-8 filaments, or 7 or 8 filaments, and, on the other hand, such multifilaments still have a long lasting insecticidal release from the yarn, making it highly suitable for LLIN. For this reason, in a further embodiment, the article in the form of a multifilament PP yarn has a biocide and acid according to the above incorporated and the number of filaments is 3-12, for example, 5-9 or 6-8. Optionally, the biocide is an organic biocide.

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. US 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 3-12 or even 5-9 or 6-8 insecticidal 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.

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 to 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 PP yarn containing Deltamethrin. For other applications, for example greenhouse nets and insecticidal fences, the multifilament 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 PP matrix 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 into the PP 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 crys- talline 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 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 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. For example, the multifilaments are made of at least 75% PP, or even at least 90% PP or 100% PP.

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 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.

For long lasting insecticidal nets, yarn with the following combination of properties has been found to be good candidate. The yarn has a weight of 75 to 150 Denier, optionally 100 Denier, and 3-12 or 5-9 identical polypropylene filament, for example 7-8, into which 1-20 g Deltamethrin per kg polypropylene has been incorporated. The polypropylene also contains an acid, optionally 2-30 g/kg of an acid or 2-8 g/kg, or 3-5 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 yarn 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 simultaneously extruded in a single extruder and then assembled into a single multifilament yarn, for example in a 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 with polypropylene yarns containing Deltamethrin. However, other biocides in connection with the invention in general are insecticides including but not limited to pyrethroids, organophosphates, carbamates, pyrroles, pyrazoles, neonicotinoids cyclodienes, organochlorines, nereistoxin analogues, or diamides; a combinations of at least two of these may be used as well. A large number of possible biocides/insecticides including other pyrethroids is listed in greater detail in Bayer's patent application WO2009/012887 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, or uniforms; horse blankets, covering in agriculture and viniculture; fabrics or nettings for packages, wrapping sacks; containers for food, seeds and feed; construction materials, furniture, electric wires and cables.

Further special applications in connection with the invention are as,

- fencing; for example as disclosed in WO03003827,

- pesticidal blanket; for example as disclosed in WO03055307,

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

- air cleaning canopy; for example as disclosed in WO2006024304,

- tarpaulins; for example as disclosed in WO 03/063587,

- fabrics or nets for covering the space between the upper edge of a wall and the underside 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 method for providing stability for a biocide in polypropylene, the method comprising

- providing a thermoplastic polymer for extrusion,

- wherein the thermoplastic polymer of the matrix comprises at least 75% polypropylene,

characterised in that the acid is at least one 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, Aminocaproic Acid, Aminocinnamic 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, Benzylidene- malonic Acid, Boric Acid, Borofluoroacetic Acid, Brassylic Acid, Bromic Acid, Bromous Acid, Bromoacetic Acid, Bromohydrocinnamic Acid, Bromomalonic Acid, Bromopropi- Acid, Bromopropionic Acid, Bromosuccinic Acid, Bucloxic Acid, Butylnaphtalenesul- fonic 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, 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, Hydroxy decenoic Acid, Hydroxyglutaric Acid, Hydroxyhexadecanoic Acid, Hydroxyheptanoic Acid, Hy- droxyisophthalic Acid, Hydroxylinoleic Acid, Hydroxynaphtoic Acid, Hydroxyocta- decanoic Acid, Hydroxyoctadecenoic Acid, Hydroxypalmitic Acid, Hydroxypentanoic 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, lodous 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 ;

Lactic Acid, Levofolinic Acid, Levulinic Acid, Licanic Acid, Lipoic 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, Para- phenylenediacetic Acid, Parasulfamidobenzoic Acid, Paratoluenesulfinic Acid, Para- toluenesulfonic Acid, Paroxybenzoic Acid, Pentadecadienedioic Acid, Pentadecanedioic Acid, Pentadecatrienedioic Acid, Peracetic Acid, Perbenzoic Acid, Phenoylsulfonic Acid, Phenylacetic Acid, Phenlyacrylic Acid, Phenylaminoacetic Acid, Phenylbenzoic Acid, Phenylbutanoic Acid, Phenylchloroacetic Acid, Phenyldecanoic Acid, Phenyldodecanoic Acid, Phenyleicosanoic Acid, Phenylenediacetic Acid, Phenylglycinecarboxylic Acid, Phenylglycolic Acid, Phenylglyoxylic Acid, Phenylheptadecanoic Acid, Phenylheptanoic Acid, Phenylhexadecanoic Acid, Phenylhexanoic Acid, Phenylisocrotonic Acid, Phenylnonadecanoic Acid, Phenylnonanoic Acid, Phenyloctadecanoic Acid, Phenyloctanoic Acid, Phenylpentadecanoic Acid, Phenylpentanoic Acid, Phenylpropanoic 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; A method according to claim 1, wherein the thermoplastic polymer is a blend of polymers and comprises at least 75% polypropylene homopolymer.

A method according to claim 1 or 2, wherein the thermoplastic polymer of the matrix comprises at least 90% polypropylene.

A method according to claim 1, wherein the thermoplastic polymer is a blend of polymers and comprises at least 90% polypropylene homopolymer.

A method according to any preceding claim, wherein the the thermoplastic polymer is a blend of polymers only being homopolymers

A method according to claim 1, wherein the thermoplastic polymer is a polypropylene batch.

A method according to any preceding claim, wherin the acid has a pKa of 1 to 9.

A method according to claim 7, wherin the acid has a pKa of 1.9 to 9.

A method according to claim 8, wherein the acid has a pKa of 2 to 6.

A method according to any preceding claim, wherein the molecular weight of the acid is less than 1500.

A method according to claim 10, wherein the molecular weight of the acid is less than 1200.

A method according to any preceding claim, wherein the mathematical product of a pKa of the acid and the molecular weight of the acid is less than 1500.

A method according claim 12, wherein the mathematical product of a pKa of the acid and the molecular weight of the acid is less than 1000.

14. A method according to any preceding claim, further comprising causing gradual migration of the biocide from inside the matrix to a surface of the matrix.

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

16. A method according to claim 15, wherein the biocide is an insecticide or wherein the wherein the group of biocides comprises at least one insecticide.

17. A method according to claim 16, wherein the insecticide is Abamectin, Chlor- fenapyr, Deltamethrin. Dinotefuran, Fipronil, Imidacloprid, or Pyriproxyfen or wherein the wherein the group of biocides comprises Abamectin, Chlorfenapyr, Deltamethrin, Dinotefuran, Fipronil, Imidacloprid, or Pyriproxyfen.

18. A method according to claim 16, wherein is the biocide is Deltamethrin or wherein the wherein the group of biocides comprises Deltamethrin.

A method according to claim 18, comprising adding Deltamethrin to the thermoplastic polymer at a concentration of 1-20 g Deltamethrin per kg polypropylene.

A method according to any preceding claim, comprising adding acid to the thermoplastic polymer at a concentration of 1-30 g acid per kg of the thermoplastic polymer.

21. A method according to claim 20, wherein the acid concentration is 1-15 g acid per kg of the thermoplastic polymer. 22. A method according to claim 20, wherein the acid concentration is 1-5 g acid per kg of the thermoplastic polymer.

23. A method according to any preceding claim, wherein the method comprises pro- providing a first polypropylene masterbatch with the acid and without biocide, providing a second masterbatch with the biocide and without acid, and blending the masterbatches in the extruder.

A method according to any preceding claim, wherein the method comprises blending 1-20 g Deltamethrin and 1-30 g acid per kg of polypropylene, extruding the blend into a multifilament yarn having 5-10 filaments, and weaving the yarn into a mosquito net.

A method according to claim 24, wherein the concentration of Deltamethrin is 1- g/kg polypropylene and the concentration of the acid is 1-5 g/kg polypropylene.

An article comprising 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% polypropylene by weight of the thermoplastic polymer, wherein also an acid is distributed throughout the matrix, and wherein the acid is at least one 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, Aminocaproic Acid, Ammocinnamic 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, An- sulfuric 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, Borofiuoroacetic Acid, Brassylic Acid, Bromic Acid, Bromous Acid, Bromoacetic Acid, Bromohydrocinnamic Acid, Bromomalonic Acid, Bromopropionic Acid, Bromosuccinic Acid, Bucloxic Acid, Butylnaphtalenesulfonic 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- 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, Iso vanillic Acid, Itaconic Acid ;

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

Octadecanedicarboxylic Acid, Octadecanedioic Acid, Octadecenedioic Acid, Octadi- enedioic Acid, Octenedioic Acid, Octadecadienedioic Acid, Octatrienedioic Acid, Octa- decatrienedioic 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, Para- phenylenediacetic Acid, Parasulfamidobenzoic Acid, Paratoluenesulfinic Acid, Para- toluenesulfonic Acid, Paroxybenzoic Acid, Pentadecadienedioic Acid, Pentadecanedioic Acid, Pentadecatrienedioic Acid, Peracetic Acid, Perbenzoic Acid, Phenoylsulfonic Acid, Phenylacetic Acid, Phenlyacrylic Acid, Phenylaminoacetic Acid, Phenylbenzoic Acid, Phenylbutanoic Acid, Phenylchloroacetic Acid, Phenyldecanoic Acid, Phenyldodecanoic Acid, Phenyleicosanoic Acid, Phenylenediacetic Acid, Phenylglycinecarboxylic Acid, Phenylglycolic Acid, Phenylglyoxylic Acid, Phenylheptadecanoic Acid, Phenylheptanoic Acid, Phenylhexadecanoic Acid, Phenylhexanoic Acid, Phenylisocrotonic Acid, Phenylnonadecanoic Acid, Phenylnonanoic Acid, Phenyloctadecanoic Acid, Phenyloctanoic Acid, Phenylpentadecanoic Acid, Phenylpentanoic Acid, Phenylpropanoic 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;

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;

27. An article according to claim 26, wherein the thermoplastic polymer is a blend of polymers and comprises at least 75% polypropylene homopolymer.

28. An article according to claim 26, wherein the thermoplastic polymer of the matrix comprises at least 90% polypropylene.

29. A method according to claim 26, wherein the thermoplastic polymer is a blend of polymers and comprises at least 90% polypropylene homopolymer.

30. An article according to any one of the claims 26-29, wherein the the thermoplastic polymer is a blend of polymers only being homopolymers

31. A method according to any one of the claims 26-30, wherein the polymer comprises 5%-10% HDPE.

32. An article according to claim 26, wherein the thermoplastic polymer of the matrix is only polypropylene.

33. An article according to any one of the claims 26-33, wherin the acid has a pKa of 1 to 9.

34. An article according to claim 34, wherein the acid has a pKa of 1.9 to 9.

35. An article according to claim 34„ wherein the acid has a pKa of 2 to 6 36. An article according to any one of the claims 26-35, wherein the molecular weight of the acid is less than 1500.

37. An article according to claim 36, wherein the molecular weight of the acid is less than 1200.

An article according to any one of the claims 26-37, wherein the mathematical product of a pKa of the acid and the molecular weight of the acid is less than 1500.

39. An article according to claim 38, wherein the mathematical product of a pKa of the acid and the molecular weight of the acid is less than 1000.

40. An article according to any one of the claims 26-39, wherein the insecticide is Abamectin, Chlorfenapyr, Deltamethrin. Dinotefuran, Fipronil, Imidacloprid, or Pyriproxyfen or wherein the wherein the group of biocides comprises Abamectin, Chlorfenapyr, Deltamethrin, Dinotefuran, Fipronil, Imidacloprid, or Pyriproxyfen.

An article according to any one of the claims 26-39, wherein the biocide is Deltamethrin or wherein the group of biocides comprises Deltamethrin.

An article according to claim 41, wherein the Deltamethrin has a concentration of 1-20 g Deltamethrin per kg polypropylene.

An article according to claim 42, wherein Deltamethrin has a concentration of 1-7 g Deltamethrin per kg polypropylene.

An article according to any one of the claims 26-43, wherein the acid concentration is 1-30 g acid per kg of the thermoplastic polymer.

An article according to claim 44, wherein the acid concentration is 1-15 g acid per kg of the thermoplastic polymer.

46. An article according to claim 45, wherein the acid concentration is 1-5 g acid per kg of the thermoplastic polymer.

47. An article according to any one of the claims 26-46, wherein the article is a yarn.

48. An article according to claim 47, wherein the article is a multifilament yarn.

49. An article according to claim 48, wherein the number of filaments is 3 to 12.

50. An article according to claim 48, wherein the number of filaments is 5 or 9.

51. An article according to any one of the preceding claims 47-50, wherein the weight of the yarn is 75 denier to 150 denier.

52. An article according to any one of the preceding claims 47-51, wherein the filaments each have a weight of 12 to 17 denier.

53. An article according to any one of the claims 47-52, wherein the filaments are identical.

54. An article according to any one of the claims 47-52, wherein at least one of the filaments contains a first biocide and at least one of the other filaments does not contain the first biocide but contain a second biocide different from the first biocide.

55. A multifilament yarn according claim 54, 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.

56. An article according to any one of the claims 47-55, wherein the article is a yarn in a mosquito net.

57. An article according to claim 56, wherein the article is a mosquito net made of multifilament yarn with a weight of 75-150 Denier and 3-12 identical polypropylene filaments into which 1-20 g Deltamethrin and 1-30 g acid per kg polypropylene have been incorporated, and wherein the article comprises less than 0.01 g/kg of fatty acid.

Use of an method according to any one of the claims 1-25 for reducing or eliminating a detrimental chemical effect of PP on an alkaline-sensitive biocide after extrusion.

Use according ot claim 58, wherein the alkaline-sensitive biocide is Abamectin, Chlorfenapyr, Dinotefuran, Fipronil, Imidacloprid, or Pyriproxyfen

60. Use according to claim 59, wherein the alkaline-sensitive biocide is Deltamethrin.