WO2014086666A1

WO2014086666A1 - Method to produce an insecticide-containing fabric

Info

Publication number: WO2014086666A1
Application number: PCT/EP2013/075034
Authority: WO
Inventors: Jens Hepperle; Philippe Guimbard
Original assignee: Bayer Cropscience Ag
Priority date: 2012-12-04
Filing date: 2013-11-29
Publication date: 2014-06-12
Also published as: CN104838060A; JP2016507659A; CN104838060B; ZA201504810B; KR20150091335A

Abstract

The present invention relates to an improved method to produce an insecticide-containing fabric containing at least one embedded insecticidal alkaline-sensitive active ingredient in the polymeric matrix. The present invention also relates to methods to prolong the lifetime (including storage and use) of alkaline-sensitive insecticide-containing fabrics.

Description

Improved Method to Produce an Insecticide-containing Fabric

The present invention relates to an improved method to produce an insecticide-containing fabric containing at least one embedded insecticidal alkaline-sensitive active ingredient in the polymeric matrix. The present invention also relates to methods to prolong the lifetime ( including storage and use) of alkal ine-sensitive insecticide-containing fabrics.

Long lasting insecticidal nets (LLINs) have been proved to be effectiv e against the reduction of mosquito populations and malaria incidence. Various LLINs are (or intended to be ) commercialized which use polymeric materials such as polyethylene, polypropylene and polyester and insecticides such as Deltamethrin, Alpha-Cypermethrin and Pcrmethrin (see WHO recommended LLINs: http://www.who.int/whopes/Long lasting insecticidal nets Jul 2012.pdf). Some of the insecticides used for LLINs are described to be pH sensitiv e and suggest ions hav e been made how to av oid unwanted degradation of alkaline-sensit iv e insecticides ( e.g. Deltamethrin and Pcrmethrin) during production of the LLINs (WO201 1/124227A1). In particular it was proposed to blend an acid with the alkaline-sensitive insecticide and the thermoplastic polymer during production in order to make the acid an integral part of the finally produced LLIN. However, the solution proposed in WO201 1 124227A 1 might lead to a reduction of mechanical stabil ity of the fabric due to addition of acid in the form of solid particles. Moreover, acidity generated by the added acids might lead to unwanted toxicity for the user, e.g. caustic properties to the skin during use due to the acid on the yarn surface. I n light of the prior art it was an object of the present inv ention to address the problem of degradation/raccm isation of alkal ine-sensitiv e insecticides used for LLINs during production (and use) but to av oid the generation of LLINs with potential unwanted characteristics. In particular, the present invention aims to reduce the formation of the amounts of insecticidal inactive isomers of Deltamethrin such as l ike the R-alpha isomer of Deltamethrin, subsequently also referred to as R- alpha Isomer and to retain a high amount of insecticidal activ e Deltamethrin isomer ( the S-alpha Isomer). With the present inv ention it has now been found that the problem can be solved by a method for producing a polymeric fabric, wherein a polymer and one or more alkal ine-sensitive insecticidal act iv e ingredients are melted together or separately at temperatures between 120 and 250°C, the melt is formed into spun threads and a spin finish is used in the course of the spinning of the threads, spun threads formed are cooled, and led through a draw ing system, drawn and knitted to form a fabric which is subsequently subjected to a heat-setting operation characterized in that the polymeric fabric is washed prior to the heat-sett ing operation:

- with acidic water at a pH-v alue of below 5, or

- with water and a detergent under acidic conditions at a pH- value of below 5, or - with a detergent comprising alkylarylsulfonate(s), fatty acid ethoxylate(s) and/or fatty alcohol ethoxylate(s) and/or

- an acidic spin finish is applied to the threads in the course of spinning of the threads (which makes the washing step prior to the heat-setting operation optional).

The method of producing a fabric which includes a washing step before the heat-setting operation and the use of a spin finish is described in WO201 1/141260A1. However, opt imal washing conditions as well as the use of an acidic spin finish during production were not discussed in WO201 1/141260A1. The use of acidic washing bath or acidic spin finish is also not described in WO201 1/124227A1.

For the present method of producing a polymeric fabric, thermoplastic polymers such as polyolcfins (polyethylene, polypropylene and the like), polyesters (polyethylenterephthalates and the l ike ) and polyamides as wel l as combinations of fabric made out of di fferent polymers can be used. Preferably, however, polyolcfins and in particular polypropylene and also polypropylene copolymers are used. More preference is given to using polypropylene. A multiplicity of poiypropylenes are know n from the prior art. Polypropylenes can in principle be distinguished according to their manner of synthesis. The main proportion of poiypropylenes is produced in the presence of Ziegler-Natta catalysts in the suspension process or more particularly in the so-called gas phase process (cf. Kaiser "Kunststoffchem ie fur ingenieure^", pages 246 to 254). The gas phase process can also utilize specific catalysts such as metal locenes. The polymers produced using metal loccne catalysts arc particularly useful as polymeric matrix for the insecticide-containing polymeric material to be used according to the present invention. The melting points of polypropy lenes produced using metal loeene catalysts arc usual ly distinctly below those avai lable using conventional heterogeneous catalyst systems. The insecticide-containing polymeric material of the present invention preferably utilizes polypropylenes intended for the melt-spinning process to produce fi laments, fibres and spunbondeds. Particular preference is given to using polypropylenes useful for the product ion of multifilaments hav ing a low linear density of 50 to 150 denier. These are for example polymers bearing the brand names Metocene^® and Moplen* ( from Lyondell Basell, Netherlands), Repol^® ( Reliance Industries Limited, I ndia ), Yuplen^® (SK corporation, South Korea ), Seetec^® (LG Chemical, South Korea ), PPH^® and Lumicene^® grades (Total Petrochemicals, Belgium ) and Achieve* (ExxonMobile Chemical Company, USA). Particular preference is given to metal locene-catalysed polypropy lenes, for example Metocene^® I I M562S, melt ing temperature 145°C ( from Lyondell Basell, Netherlands) and Achieve* 3845 ( ExxonMobi le Chemical Company , USA). The polymeric materials used can be produced with the addition of additives which are incorporated into the polymer to stabilize or improve its processing properties. Suitable additives are for example alkylated monophenols, alkylthiomethyl phenols, hyclroquinones, tocopherols, hydroxyiated thiodiphenyl ethers, alkyl idenebisphenols, 0-, N- and S-ben/yl compounds, hydroxybenzylated malonatcs, aromatic hydroxybenzyl compounds, triazine compounds, acylaminopheno!s, esters of [V( 3,5-di-tert-butyl-4-liydroxyphetiyl)propionic acid with mono- or polyhydric alcohols, esters of P-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic ac id with mono- or polyhydric alcohols, esters of P-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid w ith mono- or polyhydric alcohols, esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or polyhydric alcohols, amides of β-( 3,5-di-tert-butyl-4-hydroxypheny I (propionic acid, ascorbic acid ( Vitamin C) and aminic antioxidants, i t is likewise possible to use thiosynergists, secondary antioxidants, phosphite* and phosphonites.

I t is l ikewise possible to produce the polymeric materials used by using metal deactivators, peroxide scavengers, basic costabilizers, nucleating agents, plasticizers, lubricants, emulsifiers, pigments, viscosity modifiers, catalysts, flow control agents, optical brighteners, flameproofing agents, antistatic agents and blowing agents, benzofuranones and indoiinones, fluorescent plasticizers, mould release agents, UV stabilizers, flame-retardant additives, antistat ic agents such as sulphonate salts, pigments and also organic and inorganic dyes and also compounds containing epoxy groups or anhydride groups. To produce the fabric of the present invention, first the polymeric material, preferably polypropylene, an alkaline-sensitive insecticidal active ingredient and optionally (but preferably) likewise a UV stabilizer and optionally further insecticides or additives are melted together or separately at temperatures between 120 and 250°C, preferably 150 and 230°C, and subsequently the cooling and solidifying of the polymeric mixture takes place and also the subdiv ision of the latter into pellets.

In addition to insecticides, it is optional ly possible ( and preferable) to use UV stabilizers (i.e. UV absorbers and. or light stabilizers) in an amount of 0.01% to 15% by weight, preferably 0.03% to 8% by weight, based on the total mass of the composition of the insecticide-containing polymeric material. UV absorbers and/or light stabilizers useful for carrying out the process are for example 2-(2'-hydroxyphenyl)benzotriazoles, 2-hydi oxyben/ophenoncs, esters of substituted and unsubstituted benzoic acids, acrylates, nickel compounds, sterically hindered amines, oxamides, 2- (2-hydroxyphenyl )- 1 ,3,5-triazines and also m ixtures thereof. Preferably no sterical ly unhindered amines are used as UV stabilizers, but 2-(2'-hydroxyphenyl)benzotriazoies, 2- hydroxybenzophenones, esters of substituted and unsubstituted benzoic acids, acrylates, nickel compounds, oxamides, 2-( 2-hydroxyphenyl )- 1 ,3,5-triazines and also mixtures thereof are used. Particular preference is given to triazine compounds and butrimezole. Very particular preference is given to phenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyi-, branched and linear (CAS 125304- 04-3) and 2-(5-chloro-2H-benzotriazol-2-yl)-6-(l , l -dimethyiethyl)-4-methyiphenol (CAS 3896- 1 1- 5). The polymeric material to be used is for example melted in a single-screw extruder, a twin-screw extruder, a multi-screw extruder or a co-kneader. The single-screw extruder used can be for example a smooth or grooved barrel extruder or a Transfermix. A grooved barrel extruder is preferred. Twin-screw extruders may be co- or counter- rotating. Twin-screw extruders may further be closc-mcshing or non-intermcshing. Preference is given to a close-meshing corotating configuration. Multi-screw extruders have at least three screws, preferably four to twelve. The screws may each be arranged to form close-meshing pairs, in which case the screw pairs can be arranged tangentially and counter-rotating relativ e to each other. The screws of a multi-screw extruder can further be all corotating, in which case each screw intermeshes in two neighbouring screws. A special form of multi-screw extruder is the planetary roll extruder wherein a driven central spindle drives freely revolving planetary spindles which in turn circulate in a fixed housing. The central spindle, the planetary spindles and the housings hav e toothed-wheel intermeshing. The manufacturing method of the present inv ention is particularly preferably carried out using a close- meshing corotating twin-screw extruder. The construction of the extruder screw is adapted to the respective application scenario. Room temperature solid alkaline- sensitive insecticides, optionally UV stabilizers and other additiv es are in a preferred embodiment metered together with the start ing polymer pellets into the feed zone of the extruder, in another preferred embodiment, room temperature solid alkaline- sensitiv e insect icides, UV stabilizers and other additiv es are melted and metered in l iquid form. The extruder housings are temperature controlled to 4 to 250°C. The extruder housing at the feed zone of the extruder is preferably cooled to 4 to 50°C. The remaining extruder housings are preferably temperature controlled to 100 to 250°C and more preferably to 140 to 250°C. I n the extruder, the polymer and, depending on the melting point, the insecticide as well and also the UV stabilizer are melted and mixed. The mixture is extruded through a hole die and pelletized. The additiv es may also comprise further inorganic or organic fil lers such as for example organic pigments, titanium dioxide, carbon black or talcum. The residence times in which the polymer is liquid during melting and mix ing are between 3 and 300 seconds, preferably between 5 and 120 seconds and more preferably between 8 and 30 seconds. The mixing of the insecticide, optionally of the UV stabilizer and of other additiv es with the molten polymer can take place in the same apparatus in which the melt ing of the polymer takes place, or in a further apparatus. A 11 the abov ementioned extruders are suitable for the mix ing. A further possibility is to mix the insecticide and. where appropriate, the additiv es with the polymer in a static mixer. The mixing is preferably carried out with a static mixer. When the insecticide or the additives is added in liquid form, it is generally melted and intermediately stored in an initial charge vessel, from which it is then conveyed into the mixing apparatus. The conveying can be effected for example via a pump or via an increased admission pressure. The temperature of the initial charge vessel is chosen such that the insecticide is stable and the viscosity of the insecticide is sufficiently smal l to ensure good pumpability. It is advantageous in this case to heat the initial charge vessel, the pump and all l ines. The metering into the mixing apparatus preferably proceeds v ia a needle valve. The metered amount of insecticide is preferably measured by a suitable mass flow rate meter, for example according to the Coriolis principle or according to the heated wire principle, and closed-loop controlled to small dev iations via the pump or a valve. Room temperature liquid alkaline-sensitive insecticides are added to the already molten polymer in a processing zone of the extruder via a needle valve. Depending on the viscosity and melting point of the alkaline-sensitive insecticide, the alkaline-sensitive insecticides, UV stabilizers and other addit ives or their mixture are heated for this. After mixing, a preferred embodiment comprises cooling and solidifying of the polymeric materials and also subdiv ision into pellets. This can be accomplished for example using the common strand pelletization process wherein one or more dies extrude continuous strands which are then air or water cooled to sol idi fy them and subsequently comminuted to the desired size in a pelletizer. Underwater pelletization is a further method, the melt emerging from the die underwater, being cut there and by a circulat ing blade and subsequently water cooled, thereafter screened off and dried. A further method is water ring pelletization where the polymer is cut in the liquid-melt state in air and thereafter whizzed by centri fugal forces in a rotating water ring to cool. Particular preference is given to the method of underwater pelletization and to the strand pelletization process.

I n one embodiment of the process of the present invent ion, only polymeric material produced by the mixing operation is fed to a subsequent processing operation. The amount of alkaline-sensitive insectic ide in the simple mixing operation is in the range from 0.05% to 15% by weight, preferably in the range from 0.2% to 10% by weight and more preferably in the range from 0.4% to 8% by weight, based on the total mass.

I n a further embodiment, a polymeric material having an increased concentration of alkaline- sensitive insccticidal activ e ingredient is produced in pel let form (known as a masterbatch ) and fed to a subsequent processing operation in a mixture with untreated polymer. In this case, the concentration of alkal ine-sensitive insect icide in the masterbatch polymeric material of the present invention is increased, preferably to a concentration between 3 to 20% by weight and more preferably 5% to 15% by weight based on the total mass. A further embodiment comprises a first step of producing the polymeric material of the present invention as a masterbatch which thereafter, by melting and mixing with untreated polymer and possible further additives, is again further processed into a polymeric material of the present invention, which is generated in the form of pellets. The subsequent processing operation may comprise for example the resulting pellets of the polymeric material of the present invention being processed in a processing step into shaped articles such as alkaline- sensitive insecticide-containing polymeric material in a subsequent spinning operation to form fibres, yarns, filaments or preferably threads.

Some suitable insecticidal alkaline-sensitive active ingredients for the fabric of the present invention are discussed in WO201 1 124227 A 1 and are preferably selected from the group of Abamectin, Acephate, Acequinocyl, Acetamiprid, Azadirachtin, Bendiocarb, Beta-Cycfluthrin, Bifenazate, Bifenthrin, Buprofezin, Chlorphenapyr, Chlorpyrifos, Clofentezine, Clothianidin, Cyfluthrin, Cyromazine, Deltamethrin, Dinotefuran, Diflubenzuron, Ethiprol, Etoxazole, Fenpropathrin, Fenpyroximate, Fipronil, Flonicamid, Fiuvalinate, Imidacloprid, Methiocarb, Novaluron, Permethrin, Pyriproxyfen, Pymetrozine, Pyridaben, Rynoxapyr, Spinosad, Spiromesifen, Thiacloprid, Thiamethoxan and Transfluthrin.

The insecticides mentioned can be used individually or in a mixture.

Preferred alkaline-sensitive insecticides are Deltamethrin and Transfluthrin and mixtures thereof. The alkaline-sensitive insecticide used most preferably is Deltamethrin. The concentration of the insecticidal alkaline-sensitive active ingredient in the polymeric material can be varied within a relatively wide concentration range from, for example 0.05% to 15% by weight, preferably 0.2% to 10% by weight, more preferably 0.4% to 8% by weight. The concentration shall be chosen according to the field of application such that the requirements concerning insecticidal efficacy, durability and toxicity are met. Adapting the properties of the material can also be accomplished by mixing insecticides in the polymeric material by the blending of materials according to the present invention which contain different insecticides, or by using materials according to the present invention which contain different insecticides which are used in combination with each other, for example as mosaic nets. Custom-tailored textile fabrics are obtainable in this way. In the production of filaments, fibres, threads and yarns, the insecticide-containing polymeric material is initially melted, formed into spun threads and cooled, the spun threads obtained are led through a drawing system and drawn and then optionally the setting of the filaments, fibres, threads and yarns takes place. Thc threads or filaments are produced, after the mixing operation, by melt spinning as described for example in DE-A 41 36 694 (page 2, lines 27-38, page 5, l ine 45 - page 6, l ine 23 ) or DE-A 10 2005 054 653 ([0002]). in this process, the insecticidal polymer produced is melted in a single-screw extruder and forced with the aid of a gear pump through a die plate. The die plate is preceded by a fi lter pack. The polymer strands emerging from the die plate are subjected to highspeed drawing, spin finishing and winding up. The melt-spinning process comprises the steps of: preparing the spinning melt, melt spinning, cooling, spin finishing, drawing and aftcrti cating.

The fibres are produced from the molten polymeric material of the present invention using the known melt-spinning processes. Preference is given to processes for producing monofilament fibres, multifilament fibres, fibrous nonvvov en webs, hollow fibres, staple fibres, multicomponent fibres and matrix-embedded micro fibers. The production of multifilament fibres is particularly preferred. The term "thread" and the term "fibre" are used as synonyms throughout this patent application.

I n step (1), the insecticide-containing polymeric material, produced by the mixing operation, is melted at temperatures of at least 10°C below the decomposition temperature and at least 5°C abov e the melting point of the polymeric material and conveyed without cooling to the spinnerette die pack. The polymeric material is preferably melted and spun at a temperature below 250°C, more preferably below 235°C. Fibre production can be carried out in one stage by the polymeric material being fed to the spinning operation directly after mix ing, in molten form. It is sim ilarly possible to carry out a two-stage process wherein the previously produced pellets composed of the abov e-described polymeric material are melted in a conveyor extruder or in a beatable flask and conv eyed to the spin pack, in a preferred embodiment, the alkaline-sensitiv e insecticide-containing polymeric material is fed to the spinning operation directly after mix ing, in molten form. It is particularly preferable for the alkaline-sensitive insecticide-containing masterbatch polymeric material, hav ing an increased insecticide concentration, to be mixed with purely polymer material in the course of the spinning operation. The mixing can be effected in different ways. In one embodiment, the insecticide-containing polymeric material and the additional polymeric material are fed v ia two separate metering assemblies to the single-screw extruder in which the materials are melted. I n a further embodiment, the two polymeric materials are mixed prior to addition into the single-screw extruder and then supplied to the extruder in the form of a pre mix. i n a further embodiment, the insecticide-containing polymer and the unloaded polymeric material are melted in two separate extruders and these two streams of melt are subsequently mixed with each other. The spinnerette die pack consists of a known construction. The spinneret die plate can have one to several thousand die holes hav ing hole diameters customary for fibre production. After the spinnerette die pack, the spun threads pass through a cooling sector, are spin finished and are wound up or deposited in cans. The cooling medium used is a liquid or a gas. When it is a l iquid. water is used. According to the present invention, for cooling acidified water can be used. Dry cooling sectors take the form f quenching chambers in which the spun threads are cooled down with cold air, nitrogen or carbon dioxide being used as cooling gas.

A spin finish is appl ied to the fibres in the course f the spinning operation. The spin finish is usually applied as aqueous solution with 1 -50 wt% f spin finish solution distributed in water. Appl ication f the spin finish modifies the surface properties f the fibres and will remain on the yarn surface after spinning until the fabric is being knitted from the yarn. The spin finish inter alia reduces the friction between metal and thread and between thread and thread, and also reduces the antistati charging of the fibres. The appl ication of a spin finish is necessary to carry out the m lt- spinning operation. Without an appropriate spin finish, the winding and unwinding and further processing f filament yams is not possible. A person ski lled in the art knows how to adapt a spin finish for this purpose. Spin finishes are also known to a person ski lled in the art. Surprisingly, it has now been found that by using an acidic spin finish the degradation of alkaline-sensitive insecticides can be minimized. By using such an acidic spin finish it has in particular been shown that the R-aipha isomerisation f Deltamethrin can be minimized. In addition, it has been found out that by using acidic spin finish the beneath discussed washing step ( prior to the heat-setting operation) becomes opt ional. However, in a preferred embodiment f the invention, both, an acidic spin finish is used and the washing is conducted. As an acidic spin finish a spin finish can be used that has preferably a pH-valiie f 5 or below, more preferably a pH-value of below 5, even more preferably a pH-value f 4 or below, and most preferably a pH-valuc f below 4. For doing so a commercially available spin finish can be either used as neat oil r can be di luted in demineraiized water with a concentration between 5 and 20 wt% to form an emulsion which is applied on the yarn during spinning. The pH-value of the solut ion to be appl ied can be adjusted by adding an acid (preferably an organic acid) such as e.g. la tic acid, acetic acid, citric acid, formic acid, hydrochloric acid r the like. Commercially available spin finishes are know n under the tradenames Limanol, Silastol (Schill&Seilacher, Germany ), Fasavin. (Zsclii miner & Schwarz, Germany ), Duron (Breitlich GmbH ), Afilan, Appretan (Clariant AG, Switzerland), Stantex Standap l Katax Resista (Pulcra Chemicals).

The amount f the appl ied non-aqueous constituents f the spin finish is in the range from 0.1% to 3.0% by weight and preferably in the range from 0.5% to 1.5% based n the t tal mass of the fibre. The spin finish can be applied at the point f exit fr m or entry to the fibre production line, the winding take-off machine, the rew inding machine and. or the quench chamber. The spin finish, or to be more precise the mixture f spin finish and water, can be appl ied to the fibre in v arious ways. In principle, it can be applied by spraying, dipping, rolls, rods and pins. The spin finish can be meteringly added in one, two or in a plurality of stages. The wound-up or deposited spun threads is then led through a drawing system and drawn and wound up as flat fi lament, or optional ly be crimped, set or cut into staple fibres. Preferably, the spinning and drawing operations are carried out in one system without intermediate winding up of the undrawn filaments. Suitable drawing systems are draw-twist or draw-wind machines for flat multifilaments, compact mono til spin-draw systems for monofilaments, draw production lines and compact spin-draw systems for staple fibres. The drawing systems can be equipped with heatable or partly non-heatable godets or draw rolls, and also guide rollers, further with steam, hot-air and infrared ducts, coating devices, crimping units, diyers, cutting systems and other units. The drawing operation can be followed by any known finishing measure, such as the application of a coating for example. Setting the filaments or fibres is usually carried out on these systems after the drawing step. The multifilaments spun at high speed can be draw- textured on machines known for this purpose, and similarly the drawn multi fi laments can be textured. Multifilaments preferred according to the present invention have I to 100 filaments, more preferably 5 to 75 filaments and most preferably 10 to 60 filaments. According to the present invention, fibres having a linear density of 1000 to 1 0 denier, preferably 500 to 20 denier and more preferably 200 to 50 denier are used. The threads, yarns, fibres or fi laments thus produced can subsequently be further processed into any desired products such as for example textile fabrics. Preference is given for example to wovens, braids, knits, felts or nonwovens. Particular preference is given to net! ike polymeric fabrics such as mosquito nets/ sleeping nets for example.

The production of wovens and braids is effected by means of two thread systems (warp and weft) crossing each other at right angles. A knitted fabric can be produced from one thread (one-thread knit) or be constructed from two or more threads (warp-thread knit) according to the warp-thread technique. These fabrics of the present invention are produced on loop-forming or -drawing machines. It is further possible to use short threads or thread pieces to produce felts or nonwovens.

To produce the netl ike fabrics of the present inv ention by means of loop-forming and -drawing processes, it is necessary to produce a so-called warp beam. The polymeric threads are wound in equal length in a parallel arrangement on a bobbin, the so-called warp beam.

To render the polymeric threads more lubricious and robust during processing into the polymeric fabric of the present inv ention, the threads are frequently sized, i.e. coated with a protective film of starch or synthetic sizes. Sizing can be effected using a winding oil which is applied during vvarp- beam production in order to improve the winding properties during warp-beam production and to reduce thread-oii-thread friction and also friction between metal and thread. Reducing friction is important not only for warp-beam production but also for the subsequent loop-forming operation.

Prior to further treatment (for example bleaching and dyeing), polymeric fabrics composed of manufactured fibres are preferably washed, since the manufactured fibres contain small amounts of additivcs at the fibre surface. These additives comprise more particularly the above-described spin finishes, but other additiv es such as possibly applied sizes are also remov ed in the process. This washing operation may be carried out in various ways generally known to a person skilled in the art. In some processes, the washing liquor is agitated, in other processes the polymeric fabric moves through the quiescent washing liquor. Possible processes are pulsed washers, jet washers, washing on siev e drums, pad-mangles and also v acuum processes. Continuous processes are preferred on an industrial scale. i n the case of polypropylene and polyethylene fibres, this operation is not carried out in the prior art processes since polymeric fabrics composed of these polymers cannot be dyed with a dyebath. This holds more part icularly for the production of net I ike fabrics such as mosquito nets, since in this case the polymeric fabric is not subjected to any further finishing operation apart from heat setting.

I n WO201 1/141260A1 , howev er, it has been surprisingly found that the washing of a netlike fabric with comprising polypropylene respectiv ely polyethylene fibres with water and a detergent prior to the heat-setting step has been found to hav e a positive effect on the loss of insecticide during washing according to the WHO PES directiv e. All the washing processes described abov e (i.e. pulsed washers, jet washers, washing on siev e drums, pad-mangles and also v acuum processes) can be used for such a w ashing operation. With the present inv ention it has been shown that washing the fabric prior to the heat-setting operation with acidic water (without any detergents ), or w ith w ater and a detergent under acidic conditions, or with a detergent comprising al ky lary I su I fonat e( s ) , fatty acid ethoxylate(s) and/or fatty alcohol ethoxylate(s), preferably at least fatty acid ethoxylate and more preferably alkalarylsul fonate and fatty acid ethoxylate was even more effective to remov e the spin finish and to minimize R -alpha isomcration of Deltamethrin than the solution proposed in WO201 1/141260A1. Furthermore, it has also been found that when using an acidic spin finish in the course of spinning of the threads the washing step prior to the heat-setting operation needs only to be optionally carried out in order to minimize R-alpha Isomerisation of Deltamethrin. Howev er, in a preferred embodiment of the inv ent ion - both - appl ication of an acidic spin finish in the course of spinning the threads as well as the applicat ion of acidic water at a pH-v aluc of below 5, acidic water (without any detergents) at a pH-v alue of below 5, with water and a detergent under acidic conditions at a pH-v alue of below 5, or with a detergent comprising a 1 ky i a ry I s u I f o n a t e ( s ) , fatty acid ethoxylate! s) and/or fatty alcohol ethoxylate(s) is carried out in order to generate a polymeric fabric that does not hav e unw anted characteristics such as e.g. low skin to lerance compat i b i I i ty due to high acidity on the surface of the polymeric fabric or lower mechanical stability due to solid inclusions in the yam material. In a preferred embodiment of the invention, the washing step (during production of the polymeric fabric) is conducted at temperatures of between 20°C to 80°C, preferably of between 30°C to 60°C and for a period of preferably below 5 minutes, more preferably below 1 minute. I n another embodiment, the acidic water used for the washing has a pH-value below 5, more preferably a pH- value of 4 or below and even more preferably a pH-value of below 4. Acidic water according to the invention can be obtained by adding an acid (preferably an organic acid) such as e.g. lactic acid, acetic acid, citric acid, formic acid, hydrochloric acid or the like (preferred acids are selected from the group of acetic acid and citric acid) to demineraiized water to adjust the pH-value. If in addition to water also a detergent is used during the washing step (which is a preferred embodiment of the invention), such a combination has preferably a pH-v alue of below 5, preferably a pH-value of 4 or below and even more preferably a pH-v alue of below 4. Such acidic conditions can be as well be adjusted by adding the abov e discussed acids to the washing solution. Washing can also be conducted with a detergent comprising alkylarylsulfonate(s), fatty acid ethoxylate(s) and/or fatty alcohol ethoxylates, preferably at least fatty acid ethoxylate and more preferably aikalarylsulfonate and fatty acid ethoxylate. Detergents comprising such components are e.g. know n under the tradename: Rucogen FWK (from Rudolf Chemie ), Rucogen DFL 200 (from Rudolf (^'hemic), Rucogen SFW (from Rudolf Chemie), Lav onyl LGC (from Impocolor), Lavonyl. JN ( from I mpocolor), Lav onyl N BA (from Impocolor). I f such detergents are used, the washing step can even be performed at a higher pH-v alue. However, in a preferred embodiment, such detergents are used at a pH-v alue of 7 or below, preferably a pH-v alue of 5 or below and even more preferably a pH-v alue of 4 or below .

The polymeric fabric produced has very elastic properties frequently and is not in a stable form. I n this form, it is more particularly unsuitable for the production of netl ike polymeric fabrics such as mosquito nets, since this use has specific requirements in terms of shrinkage determined to D IN EN ISO 5077. Therefore, it is preferred to carry out a heat-setting operation. Heat setting can be carried out with hot water, saturated steam or hot air, or in a dry atmosphere. Preference is given to carrying out heat setting in a normal atmosphere without additional supply of water or steam. Heat setting is preferably carried out using a continuous process in which the polymeric fabric is fixed on a stenter and led through an oven on a stenter. This oven is preferably subdivided into two or more heating zones which can be indiv idually temperature controlled. During the thermal treatment, the polymeric fabric can be concurrently subjected to mechanical loading to a varying degree by stretching. This is done by mov ing the two sides of the stenter apart in the setting ov en until the desired width is reached for the formed- loop knit. The temperature to heat-set the polymeric fabric of the present inv ention is chosen 20°C, preferably 10°C, below the melting temperature of the polymer. The alkal ine-sensitive insecticide-containing fabrics of the present invention can be successfully used for ki lling harmful or nuisance arthropods, more particularly arachnids and insects. The polymeric fabrics of the present invention arc preferably used for producing mosquito nets for the protection against mosquitoes. Arachnids include mites (e.g. Sarcoptes scabiei, Dermatophagoides pteronys-sinus, Dermatophagoides farinae, Dermanyssus gal linae, Acarus siro) and ticks (e.g. Ixodes rieinus, Ixodes scapularis, Argas rcflexus, Ornithodorus moubata, Boophil ius microplus, Amblyomma hebraeum, Rhipicephalus sanguineus ).

Sucking insects include essential ly the mosquitoes ( e.g. Acdes aegypti. Acdes albopictus, Acdes vexans, Culex quinqucfasciatus, Culex tarsalis, Anopheles gambiae, Anopheles albimanus, Anopheles stephensi, Mansonia titillans), sand flies (e.g. Phlebotomus papatasii ), gnats ( e.g. Culicoides furens ), black flies (e.g. Simulium damnosum ), biting house fl ies (e.g. Sto-moxys caieitrans ). Tsetse flies ( e.g. Glossina morsitans morsitans), horseflies (e.g. Taba-nus nigrovittatus, Haematopota pluv ialis, Chrysops eaeeutiens ), common houseflies ( e.g. Musca domestica, Muse a autumnal is, Musca vetustissima, Fannia canicularis ), flesh flies ( e.g. Sareophaga carnaria ), myiasis- causing flies (e.g. Lucilia cuprina, Chrysomyia chloro-pyga, Hypoderma bovis, Hypoderma l ineatum, Dermatobia hominis. Oestrus ovis, Gaste-rophi lus intestinal is, Cochliomyia hominivorax), bugs (e.g. Cimex lectularius, Rhodnius prolixus, Triatoma infestans ), lice (e.g. Pediculus human is, Haematopinus suis, Damalina ovis), fleas (e.g. Pulex irritans, Xcnopsylla cheopis, Ctenocephalides canis, Ctenoeephal i-des felis) and sand fleas (Tunga penetrans ).

Biting insects include essentially cockroaches (e.g. Blattel la germanica, Periplaneta amcricana, Blatta orientalis, Supel la longipalpa ), beetles (e.g. Sitiophilus gninarius, Tenebrio molitor, Dermestes lardarius, Stegobium paniceum, Anobium punctatum, Hy lotrupes bajulus ), termites ( e.g. Reticul iternies luci fugus ), ants ( e.g. Lasius niger, Monomorium pharaonis ), wasps (e.g. Vespula germanica ) and larvae of moths (e.g. Ephestia elutella, Ephestia cautella, Plodia interpunctella, Hofmannophi la pseudospretel la, Tincola bisselliella, Tinea pel l ionel la, Trichophaga tapetzella ).

The materials of the present invention are preferably used against insects, particularly of the order Diptera and even more preferably against the suborder Ncmatocera.

The present invention also prov ides sleeping nets, mosquito nets, wovens, braids, knits, felts, nonwovens consisting of (or at least containing ) a polymeric fabric produced according to the process described above. Preferred are sleeping nets mosquito nets (these terms are used as synonyms throughout this patent application ). Netlike fabrics according to the present invention preferably have a minimum of 23 complete holes/cm² and on average between 23 and 29 complete holes/cm².

Another embodiment of the invent ion relates to a method to minimize R-alpha Isomerization of Deltamethrin embedded in a polymeric material comprising - coating the polymeric material with an acidic spin finish during the production of the polymeric material, and. or

- using acidic water at a pH-value of below 5; water and a detergent under acidic conditions at a pH-value of below 5 or a detergent comprising alkyiaryisulfonate(s), fatty acid ethoxylate(s) and/or fatty alcohol ethoxylate(s) during washing of the polymeric material. Minimization of R-alpha Isomerisation of Deltamethrin means - according to the present invention

- in particular that the R-aipha Isomerisation of Deltamethrin is minimized:

1 . During production in comparison to:

- the use of an alkaline spin finish, preferably having a pH-v aluc of more than 5, preferably more than 7 for producing the polymeric fabric, -washing the polymeric fabric prior to the heat-setting operation under alkaline conditions (above pH-v alue of 7) resp. with a detergent other than a detergent that comprises alkylarylsulfonate(s), fatty acid ethoxylate(s) and/or fatty alcohol ethoxylate(s)and preferably at least fatty acid ethoxylate and more preferably alkalarylsuifonate and fatty acid ethoxylate. 2. During use of the polymeric fabric in comparison to: a washing procedure as suggested according to the WHOPES directive.

Minimization of R-alpha Isomerisation of Deltamethrin within polymeric fabrics leads to a prolonged lifetime including longer storage and use of such materials which is obviously very beneficial to customers in need of such products. The term "polymeric material" according to the method to minimize the R-alpha Isomerization of Deltamethrin refers to similar materials as discussed abov e for the polymeric fabric such as poiyolefins (polyethylene, polypropylene and the like), polyesters (poiyethyienterephthalates and the like) and polyamides. According to this method, polymeric materials can be fibres, yarns, filaments, threads, polymeric fabrics (preferably a netlike polymeric fabric), sleeping nets mosquito nets, wovens, braids, knits, felts, nonw ovens as discussed above. A preferred embodiment of the invention relates to a method to minimize R-alpha Isomerization of Deitamethrin embedded in a polymeric fabric, preferably a netlike polymeric fabric, more preferably a mosquito net. comprising

- coating the spun threads (see description of above) with an acidic spin finish during the production of the polymeric fabric ( preferably a nctlike polymeric fabric, more preferably a mosquito net), and/or

- using acidic water at a pH-v alue of below 5; water and a detergent under acidic conditions at a pH-v alue of below 5 or a detergent comprising alkylarylsulfonate ( s )t , fatty acid ethoxylate(s) and/or fatty alcohol ethoxylate(s) during washing of the polymeric fabric (during the production of the final polymeric fabric and before the heat-setting operation and/or while cleaning the manufactured polymeric fabric, preferably in form of a mosquito net during use to prolong the li fetime of the mosquito net).

The same preferred embodiments as with the above described method of producing a polymeric fabric are also valid for the method of reducing the R-alpha Isomerization of Deitamethrin in regard to the preferred polymers, manufacturing steps. pH-values, preferred detergents, washing conditions, preferred spin finishes etc.

Another embodiment of the inv ention relates to a method to minim ize the R-alpha Isomerization of Deitamethrin wherein the abov e described polymeric fabric (preferably a netlike polymeric fabric more preferably a mosquito net) is washed according to the WHO PES directive with an alkaline soap preferably Sav on de Marseille and the polymeric fabric is rinsed after washing with the alkaline soap (preferably Savon de Marseille) for at least 10 seconds (preferably at least 30 seconds) with acidic water at a pH-v alue of below 5. The same preferred embodiments as discussed abov e for the other methods can be used for the "acidic water" for this method as wel l.

Efficacy directly after a wash is of great importance for polymeric fabrics used for v ector control. Fabrics composed of polyethylene for example, as known from WO 2008/032844 A2, experience a post wash cycle loss of their efficacy for some days (the so-called regeneration time), and hav e to additionally dwell for a certain time at elev ated temperature to be restored to efficacy. This procedure is inconv enient for the user and always harbours a risk that this step is not carried out and that the polymeric fabric therefore suffers a decrease in protectiv e performance. A regeneration time of less than two hours is desirable. This regeneration can be accelerated with the above described methods.

According to the present inv ention, the "WHOPES directiv e" is to be understood as meaning the directiv e "Guidelines for laboratory and field testing of long- lasting insecticidal mosquito nets^". 2005). This directive is retrievable at the following internet address:

According to the WHO PES directive, a "washing" is defined as follows: a netlike fabric (25 cm x 25 cm) is introduced into a 1 litre beaker containing 0.5 litres of deionized water and 2 g/1 of "Savon de Marseille" soap ( pH 10- 1 1 ) added just before the netlike fabric and fully dissolved in t he deionized water. After addition of the netlike fabric, the beaker is immediately introduced into a warm water bath at 30°C and shaken for 10 minutes at 1 55 movements per minute. The net like fabrics are then removed from the beaker and rinsed twice for 10 minutes at a time with clean, deionized water in the same shaking conditions as mentioned above. Thereafter, the net I ike fabrics are dried at room temperature and stored at 30°C in the dark between the washings.

EXAMPLES

Production of Samples:

The polymeric materials was produced using a corotating close-meshing twin-screw extruder having a screw diameter of 34 mm and a housing length of 1200 mm. Extruder housing temperature was 200°C in all steps and extruder speed was 160 rpm. The feed zone of the extruder was cooled with water. The extruder was used to produce a so-called masterbatch having a high concentration of Deltamethrin. To this end, 10% by weight of technical grade Deltamethrin (BCS AG, Monheim DE), 2% by weight of Tinuvin^® 326 FL (BASF (Ciba), Ludwigshafen, Germany) and 88% by weight of polypropylene (Metocene^® HM562S, LyondeliBasell, Rotterdam, Netherlands) were mixed in the extruder (TK10). Ail the materials were supplied in solid form to the feed zone of the extruder. The mixture emerged from the extruder in the form of strands and the strands were cooled in a water bath. Subsequently, the strands were comminuted by pelietization. The pellets contained about 9.2% by weight of Deltamethrin.

A second step involved producing threads by diluting about 1.1% by weight of the Deitamethrin- containing pellets produced as described above with 98.9% by weight of purely polypropylene (Metocen^® HM562S). To this end, the pellets were in each case metered into the feed zone of a single-screw extruder and melted and the two melt streams subsequently combined and mixed. In the course of spinning, about 1% by weight of Stantex^® 6051 spin finish (Fulcra Chemicals GmbH, Diisseldorf, Germany) was applied to the fibres. The fibres were subsequently drawn and wound up on bobbins. Fibre thickness was 210 dtex and the fibres consisted of 25 filaments. In the second step, the fibres were drawn down to a thickness of 1 10 dtex. Three pairs of godets were used for drawing the fibres. The temperature of the pairs of godets was 60, 80 and 120°C. The average tenacity of the fibres was 4.3 cN/dtex and the residual extension of the fibres was 51%.

The polypropylene fibres spun were subsequently used to produce the formed-loop knits according to the invention (i.e. the netlike fabrics) for further testing. To this end, the first step was to produce a warp beam by winding the polypropylene fibres from the individual packages in a parallel arrangement onto one bobbin, the so-called waip beam. These warp beams were subsequently used in a warp-knitting machine to produce the formed-loop knit.

A portion of the untreated formed-loop knit was subjected to a heat-setting operation on a laboratory scale. This was done using a Mathis DHe 61599 type laboratory steamer. Prior to heat setting, a portion of the pieces of formed-loop knit was washed once. In each case 2g untreated formed-loop knit was washed in a column of 10 ml heated water bath, made of demineralized water with varying pH (pH 3, pH 5, pH 7) and varying additives of commercial detergents (no detergents, Lavonyl LGC (from Impocolor), 2g/l Savon de Marseille, 3g/l Radopal GX/2000 (from Baur Gabel ), 2g/l Rucogen FWK (from Rudolf Chemie), lg/1 Rucogen DFL 200 ( from Rudolf Chemie), 5g/l Rucogen SFW (from Rudolf Chemie), 2g/l Lav onyl LGC (from Impocolor), 2g/i Lav onyl JN ( from Impocolor), 0.4g/l Lavonyl NBA ( from Impocolor), 4g/l Invatex MD (from Huntsman), l ,5g/L Invatex CS/ 4g/l Ultravon PRE ( from Huntsman) at a temperature of 60 °C for 30 seconds. The pi I of the washing bath was adjusted via adding appropriate amounts of citric acid until the desired pH was reached. The net pieces were wrung out and then hung up for at least 1 hour to dry at room temperature. The head-setting operation was then carried out at 140°C for 30 seconds. The samples where than stored in an oven at 54 °C for 2 weeks (2w/54°C) and were analyzed after storage for the content of Deltamethrin and its R-alpha isomer. Analysis of Deltamethrin and R-alpha Isomer in Different Polypropylene Samples

Part A -- sample preparation:

About 1 g of material of a representative sample (yarn, fabric or pellet) is placed in a 250 ml flask; then approximately 30 ml of xylene (PA quality) are added. The sampic material is then dissolved at precisely 3 minutes in an oil bath at 190°C under reflux (water-cooled column, 20 cm) and stirring ( 1 25 revolutions per minute, magnetic stirrer and stirring bar). The oil bath is removed and about 10 ml of isopropanol ( PA quality) are added and the flask is left to cool for about 5 minutes at room temperature to precipitate the polymer. Thereafter the extract is made up w ith 30 ml of acetonitrile.

The sample is subsequently filtered off with suction (analy tical filter, 5 cm diameter) and thereafter the filtrate is passed through a fluted filter (MN 71 5, 240 mm ). Both filtrations are done by washing with 10-20 ml of solvent (acetonitrile) in each case.

Finally, the filtrate is quantitatively transferred into a 100 ml graduated flask and made up with acetonitri le to the calibration mark.

Part B quantitativ e determination by H PLC versus external standard: The quantification of Deltamethrin in samples of polypropylene extracts is carried out by means of H PLC on an Agilent 1 100 instrument equipped with a binary pumping system. Deltamethrin and the R-alpha isomer are the target molecules of the analysis. Certified analytical standards are used as reference materials. Separation is carried out under normal phase conditions on a Merck Lichrosorb S i 60 column (5 μ particles, dimensions 250 x 4 mm ) at 40°C column temperature. The injection v olume is 10 μΐ ( sample preparation see Part A above). Separation is effected by means of a solv ent mixture of N-heptane and methyl tertiary-butyl ether (950+50, H PLC quality ) at a flow rate of 1 ml per minute. The clution time under these conditions is 10 minutes. UV detection at a wavelength of 230 nm utilizes a diode array detector. The typical retention time under the conditions described is about 6.3 minutes for the R-alpha isomer and 7.0 minutes for the Dcitamethrin.

I n Figure 1 , the R-alpha isomer content ( X R-alpha) after storage was calculated using the concentrations of Deltamethrin (cJDLT) and the concentrations from R-alpha isomer (c R-alpha ) within the stored nets with the formula: X R-alpha = c R-alpha c DLT. cDLT equals c( R-alpha isomer and S-alpha isomer of DLT). From Figure 1 it can be seen that acidic water; water and a detergent under acidic conditions or a detergent comprising aikylarylsulfonate(s), fatty acid ethoxylate(s) and/or fatty alcohol ethoxylate(s) (e.g. Lavonyl NBA, Lavonyl LGC) lead to lower isomerization of the Deltamethrin.

Figure 2 shows the R-alpha isomer content of samples that were washed prior to the heat-setting as discussed above (at a temperature of 60 °C for 30 seconds) with Savon de Marseille (as recommended pursuant to the WHOPES directive) and samples that were washed with Savon de Marseille (at a temperature of 60 °C for 30 seconds) and then rinsed for 10 seconds at 60 °C with water that contained citron acid (adjusted to pH = 3). Rinsing with water containing citric acid remarkably reduced the isomerisation of Deltamethrin (about a factor of 10). In comparison to that data is also shown of samples that were washed with Lavonyl NBA at pH 5 and pll 3 which also reduced isomerisation of Deltamethrin considerably. The samples were analysed with HPLC as discussed above directly after the heat-setting step and after storage in an oven at 54 °C for 2 weeks (2w/54°C).

Figure 2:

Influence of the Acidity of the Spin Finish

A mixture of pure spin finish and Deltamethrin was prepared by weighting 0.1 g of Deltamethrin and adding the spin finish solution to a total amount of 10 g. Two different spin finishes were used, one regular spin finish Dakolub LI 863 TW from Dako AG with a pH of 6.43 of a 1 wt% spin finish solution in 342 ppni water and an acidic version of Dakolub LI 863 TW with a pH of 4.43 of a 1 wt% spin finish solution in 342 ppm water .

The spin finishes were added to 0.1 g of Deltamethrin to give a total amount of 10 g. The sample was stirred for 2 hours at room temperature and div ided into two parts after mixing. The samples were stored for 2 weeks at 54°C and then analysed after storage. The content of Deltamethrin and S-alpha isomer was determined using HPLC analysis as described above.

Figure 3 shows S-alpha isomer content of samples that were either stored in the spin finish Dakolub L I 863 TW or the acidic Dakolub LI 863 TW. The contact of Deltamethrin with an acidic spin finish reduced isomerisation of Deltamethrin considerably in comparison to Deltamethnn that was in contact with the same, less acidic spin finish.

Figure 3 :

Claims

Patent claims

1 . A method for producing a polymeric fabric, wherein a polymer and one or more alkaline- sensitive insecticidal active ingredients are melted together or separately at temperatures between 120 and 250°C, the melt is formed into spun threads and a spin finish is used in the course of the spinning of the threads, spun threads formed are cooled, and led through a drawing system, drawn and knitted to form a fabric which is subsequently subjected to a heat-setting operation characterized in that the polymeric fabric is washed prior to the heat- setting operation:

- with acidic water at a pH-v alue of below 5, or

- with water and a detergent under acidic conditions at a pH-v alue of below 5, or

- with a detergent comprising alkylarylsulfonate(s), fatty acid ethoxylate(s) and/or fatty alcohol ethoxylate(s) and or an acidic spin finish is applied to the threads in the course of spinning of the threads.

2. A method according to claim 1 , characterized in that the alkal ine-sensitive insecticide is Deltamethrin.

3. A method according to any of the preceding claims, characterized in that the fabric is washed prior to the heat-setting operation:

- with acidic water at a pH -value of below 5, or

- with water and a detergent under acidic conditions at a pH-value of below 5, or

- with a detergent comprising alkylarylsulfonate(s), fatty acid ethoxylate(s) and/or fatty alcohol ethoxyiate(s) and an acidic spin finish is applied to the threads in the course of spinning of the threads.

4. A method according to any of the preceding claims, characterized in that a netlikc polymeric fabric is produced.

5. A method according to any of the preceding claims, characterized in that the temperature for the heat-setting operation is chosen to be 20°C below the melting temperature of the polymer to be used.

6. A method according to any of the preceding claims, characterized in that the washing prior to the heat-setting operation is conducted

- with the acidic water at a pH-value of below 5, or

- with the water and a detergent under acidic conditions at a pH-value of below 5, and wherein the detergent comprises alkylarylsulfonate(s), fatty acid ethoxylate(s) and/or fatty alcohol ethoxylate(s).

7. A method according to any of the preceding claims, characterized in that the acidic spin finish has a pH-value of 5 or below.

8. A method to minimize R-alpha Isomcrizat ion of Deltamethrin embedded in a polymeric material comprising

- coat ing the polymer material with an acidic spin finish during the product ion of the polymeric material, and/or

- using acidic water at a pH-value of below 5; water and a detergent under acidic conditions at a pH-value of below 5 or a detergent comprising a Iky la ry Isul fonatef s ) , acid ethoxylate(s) and/or fatty alcohol ethoxylate(s) during washing of the polymeric material.

9. A method according to claim 8, wherein

- the polymeric material is coated with an acidic spin finish hav ing a pll value of 5 or below during the production of the polymer material.

10. A method according to either of the preceding claims, characterized in that the polymer is polypropylene.

1 1. A method according to one of the claims 8 to 10, wherein the polymeric material is a netlike, polymeric fabric.

12. A method according to to claim 1 1 , wherein the polymeric fabric is washed according to the WHOPES direct ive with an alkal ine soap and the polymeric fabric is rinsed after washing with the alkaline soap for at least 10 seconds with acidic water at a pH-value of below 5.

13. A method according to any of the preceding claims, characterized in that the detergent comprises alkalarylsulfonate and fatty acid ethoxylate.