1AgrEvo. A company of Hoechst and Schering

Aerosol InsecticidesA technical review

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Regions of AgrEvoEuropeAsia PacificNorth AmericaLatin AmericaInternational

Technical CentersFrankfurt am MainNarutoMontvale

AgrEvo Environmental Health plays a major role in the insec-ticide aerosol industry as a supplier of active ingredients, manu-facturing concentrates and filling solutions, backed by an unpa-ralleled technical support package.

Our expertise in this business has been developed over manyyears within the different corporate strands. Our background inaerosols started in 1949 with the Cooper, McDougall andRobertson (CM & R) company which opened Europe’s firstaerosol production line in 1949 at Berkhamsted in the UK. Sincethen we have continued to build up our aerosol expertise andthis has been given fresh impetus with the formation of AgrEvo.

AgrEvo Environmental health has 3 technical centers. Frankfurtin Germany at headquarters which concentrates ist developmentefforts on projects, new activities, collaboration with interna-tional customers. Montvale in USA which is more focused onwork crawling insect killer aerosols, and Naruto in Japan moreinvolved in the flying insect killer segment.

The expertise of AgrEvo Environ-mental Health in the aerosol fieldcovers the complete range of in-secticide products. The companyprovides a total service to aerosolmanufacturers including formu-lation advice and supply, registra-tion assistance and comprehen-sive technical support.

Research into new molecules is akey priority and as one of theworld’s leading agrochemicalcompanies we can commit con-siderable resources to the area. Inaddition AgrEvo has strong capa-bilities in the manufacture of com-plex organic chemicals such assynthetic pyrethroids. Our re-search and development facilitiesin the field of insect control havejustifiably gained a reputation forbeing amongst the best in theworld.

The AgrEvo product range in-cludes technical materials suchas synthetic pyrethroids, naturalpyrethrins and the synergistpiperonyl butoxide. Also on ourrange are manufacturing con-centrates and ready-to-use fillingsolutions, which have been spe-cially formulated to utilise appro-priate combinations of knock-down and kill insecticides in themost cost-effective way.

The expertise of AgrEvo Environ-mental Health is used by thirdparty manufacturers worldwideand is drawn upon by our custo-mers to assist in the developmentof their own formulations to meetthe specific needs of their markets.

With AgrEvo EnvironmentalHealth’s long history of formula-tion development and extensivetechnical and marketing know-ledge the company is uniquely

placed to meet the challengesahead.

AgrEvo Environmental Healthviews the insecticidal aerosol asa total system in which eachcomponent contributes to perfor-mance quality.

Our role is to help our customersoptimise the contribution of eachcomponent within the frameworkof this total aerosol system.

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The Insecticide Aerosol

Put simply, an insecticide aerosolconsists of a receptacle (normal-ly a can) containing an insecti-cide solution and a propellantmaterial. The contents are heldin the can under pressure. Whenthe button is pressed a valve isopened, the pressure forces amixture of insecticide an propel-lant up a diptube and out troughthe valve to produce the spray.

Aerosol Container

a) Aerosol containers can bemade from aluminium, plasticor glass, but most insecticideaerosols use tinplate. Tinplatecans are formed from threepieces: body cylinder with asoudronically welded sidseam, to which cone anddome end components areattached by a double lappedseam which have envelopedwithin them a rubberisedsealing compound. The tin-plate is made from steel plateelectrolytically coated bothsides with tin to a standar-dised weight per unit area.

Most cans have a 25mmaperture for the valve. Thesecans come in many sizesranging in brimful capacitiesfrom 140ml to 1000ml. Thecan may be internally coatedwith up to two layers oflacquer. Epoxy-phenolic andorganosol lacquers are themost commonly specified toprevent attack on the tinplateby corrosive products.

The tinplate can may be usedfor all insecticidal aerosolproducts.

b) Aluminium cans are normallymade in one piece, this beingan extrusion from a solid‘slug’ of metal. The shoulderand bead of the can areproduced by a succession ofcarefully controlled shaping

processes. The can is normal-ly supplied internally lacque-red as standard. Insecticideaerosols are often specified intinplate for economy, butaluminium may be specifiedif the formulation requires acan which is capable ofwithstanding very highpressures. Aluminium is resis-tant to corrosion and is emi-nently suitable for aqueousformulations, except forstrongly alkaline types such asoven cleaner containingcaustic soda. Aluminium mayalso be chosen when there isa need for a very small can orfor a print design which re-quires the total circumferenceof the can to be printed.(Aluminium cans do not havea body seam like tinplate).

Aluminium cans are usuallymore expensive than tin platecans but the reverse may be truewhere hydroelectric power isreadily available for aluminiumprocessing or where the manu-facture of tinplate has not beenestablished locally.

Strength of Containers

It is essential that the container isof adequate strength to hold iscontents safely at temperaturesup to 50 degrees C. This is themaximum temperature at whichaerosols should be stored asindicated on internationallyaccepted label texts. In theUnited Kingdom, British Stan-dard 3914 specifies minimumdistortion and burst strengths foraerosol containers. This relatesto the formulation pressuremeasured at 55 degrees C. Themaximum safe fill may be de-fined as the weight correspon-ding volume of product whichoccupies 90% of the brimfulcapacity at 55°C of the containerallowing for valve and dip tupedisplacement. The maximumsafe target fill is determined bysubtracting the filling tolerancefrom the above result. In Europe,fills for a standardised range ofcan sizes are defined by the EECPrescribed Quantities Directive.The prescribed fill is approxi-mately 75% of brimful capacity,measured at 20 degrees C, forformulations propelled by liqui-fied propellants and for compres-sed gas formulations here theOstwald Solubility Coefficient isgreater than 1.2; otherwise thefill is 60% of brimful capacity.

Gaseouspropellantexertingpressure

Concentrateand liquifiedpropellant

Liquifiedpropellantbecominggas

Liquid risingin the dip tube

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Aerosol Valve

The aerosol valve consists of:

Dip Tube

The dip tube is defined by isinternal diameter. This may be‘capillary’ (1.5mm), ‘standard’(2.5mm) or ‘jumbo’ (6mm).

Internal diameter of the dip tubeis one of the main factorscontrolling the delivery of liquidcontents.

Specially weighted flexible diptubes have been developed suchthat the bottom of the tuberemains in the liquid when thecan is used at low angles, thusproper dispensing is guaranteed.

Housing

The dip tube is attached at is up-per end to the valve housing orvalve body, which is a devicesupporting the remainder of thevalve components describedbelow. The housing orifice maybe unrestricted (open tail piece)having the same diameter as astandard dip tube, but is alsoavailable in a range of sizes(restricted tailpiece) which con-trol spray characteristics in con-junction with the other valvevariables. An additional hole,known as a vapour phase tap maybe present in the housing. Thisallows vapour from the headspaceto enter the housing. This allowsvapour from the headspace toenter the housing and mix withthe liquid travelling trough it. Thisincreases turbulence and henceatomisation energy where it isrequired. The vapour phase tap isoften specified for water-basedformulations. The vapour phasetap may also reduce flame ex-tension at a given discharge rateby modifying the edge of thespray cloud so that an increasedamount of vapour air mixture ispresent above the upper explosivelimit. Vapour phase taps are avai-lable in a range of sizes, but careis necessary in their selection suchthat significant depletion of highervapour pressure components doesnot occur from the head spaceand hence from the liquid phaseon resumed equilibrium; other-wise unacceptable decreases incan pressure will occur during thelife of the aerosol, which will ad-versely change spray characteristics.The vapour phase tap also per-mits the can to be sprayed inver-ted, although special valves whichhave a ball bearing operated flowcontrol, have been are moreadvantageous. Valves of this typeare known as 360 degree valves.

Button with Insert

Cup and Lining

ValveGasket

Stem

Spring

Housing

Dip Tube

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Valve Spring

The valve spring is seated in thehousing and ensures that thevalve stem described belowreverts to the closed positionafter spraying. The spring isnormally made from passivatedstainless steel, to provideinertness to product.

Valve Stem

The product enters the valvestem via the housing on actua-tion of the valve. The valve stemhas up to four outlet orificeswhich are available in a range ofsizes. correct choice of orificesize, in conjunction with othervalve parameters, is vital toensure correct discharge rate,droplet size distribution andcone angle for the product. Thestem is usually made from nylonor acetal copolymer, but theformer is compatible with awider range of products. Stemsmay be standard, or extended toprovent blockage in powder-based aerosols and/or undercutto provide a groove into whichflanges on the actuator can lock,to prevent actuator loosening.

Valve Inner Gasket

The orifice(s) of the valve stemare in a groove on which theinner gasket locates. This gaskethas to ensure that the productcannot escape unless the valve isactuated. The most commongasket materials include Buna orNitrile, Neoprene, Butyl, Chloro-butylic and Viton.

The choice of the correct innergasket is VITAL to ensure productintegrity THROUGHOUT is selflife. The gasket material which isselected has to be one whichundergoes a positive swell withindefined tolerances during allstages of storage under anyanticipated storage condition,such that an effective seal ismaintained.

Valve Cup

The valve cup is the supportingstructure for the valve compo-nents. It also enables the valve tobe sealed onto the aerosol con-tainer by the process known asswaging or crimping. The valvecup may be made from alumi-nium, but is usually made ofsteel, plated with tin or chrome.Additionally it may be coated onone or both sides with a protec-tive lacquer such as epoxy-phenolic or organosol.Alternatively the valve cup maybe a laminate of polypropylene,steel an PET. The valve cupnormally has to be fitted with aproduct-compatible outer gasketto effect a proper seal betweencan and valve. Types of outergasket include flowed-in com-pound, cut and polyethyleneseeves. Each of these in combi-nation with defined containersrequires specific swage diameterand depth closure dimensions toensure optimum seal. Thelaminated valve cup does notrequire a separate gasket.

Actuator (Button)

The actuator, also called thebutton or sprayhead, is fitted on-to the valve stem. Depression ofthe actuator moves the valvestem against spring pressure, and

such that the stem orifices(s)clears the inner gasket. Thisallows the head space pressureto force liquid up through the diptube and eventually out throughthe actuator. The actuator orificeis a further variable and as wellas existing in a range ofdiameters, has a passageway ofdefined length, which may bestraight, forward or reverse taper,depending on the spraycharacte-ristics required. Theactuator may additionally beequipped with an insert havingswirl chambers to providemechanical atomisation. Theinsert may be externally profiledto reduce build-up of product.Actuators are available in alvariety of mouldings accordingto product application. A spray-cap or spray-through coverperforms the functions of bothactuator and dust-cap. Thespraythrough cover trends to bechosen for air fresheners ratherthan insecticides but not throughany technical considerations.The extra cost of the componentis offset by the dust cap andbutton which are not then re-quired. Consideration of compa-tibility between formulation andthe plastic from which the spray-through cover is made wouldneed to be taken before such acover is specified.

1 Button2 Insert3 Stem4 Lining5 Gasket6 Cup7 Body8 Spring9 Dip Tube

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Chemical Componentsand Formulations

Spray Characteristics andProduct VariablesThe spray characteristics of theaerosol, i. e. droplet size distri-bution, product discharge rateand cone angle are determinednot only by choice of solventand propellants and their concen-trations but also by a vastnumber of combinations ofdifferent parameters associateswith components making up thevalve actuator system. Skill andexperience enable the optimumformulation to be defined withinconstraints of cost, biologicalperformance and flammability.

Formulation Types

Flying Insect Killer

A Flying Insect Killer aerosol(FIK) is designed to generate acloud of small droplets contain-ing insecticide. These dropletsmust remain airborne for asufficient period of time topermit adequate collection byinsects as they fly through theaerosol mist ensuring theyreceive an effective dose. Thistype of product is called a spacespray.

Most frequent targets are house-flies and mosquito species.Generally, FIK aerosols havetypical droplet sizes of between30-50 microns in diameter anddischarge rates of 1-2g persecond.

Crawling Insect Killer

A Crawling Insect Killer aerosol(CIK) is one deigned to besprayed, either directly ontocrawling insects when seen, oronto surfaces to create a depositover which insects walk andpick up a lethal does of insecti-cide.

Cockroaches are the most com-mon targets but other commoninsects such as bed bugs, fleasand ants may be killed with aCrawling Insect Killer aerosol.

For a CIK aerosol much largerdroplets are required, normallyaround 100 microns and dis-charge rates are typically inexcess of 2g pro second.

Knock-down Agents Killing Agents

Photostable DeltamethrinPyrethroids PermethrinResidual Products

Photolabile Allethrin Series: ResmethrinPyrethroids Bioalletrine® BioresmethrinNon-residual Esbiothrine®

Products Esbiol®

Natural Pyrethrums

Multi-Purpose

A Multi-Purpose insecticide aerosol is one designed to be effectiveboth as a space spray to control flying insects and as a surface spray tocontrol crawling insects. Special formulation techniques are necessaryto achieve the spray characteristics required to give effective insect killin both space spray and surface spray modes.

Active Ingredients

The selection of activeingredients is determinded bythe two major requirements ofthe aerosol namely rapid insecti-cidal performance and lowmammalian toxicity at the con-centration used.AgrEvo Environmental Healthoffers a wide and completerange of active ingredients,knock-down and killing agentswhich provide cost-effectivecombinations in aerosols.

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Optimised Formulation

The performance requirements for both space sprays and surfacesprays must be described in terms of the following parameters, whichpermit direct comparison of formulations and products:

a) KT50 - the time in minutes for 50% of a group of defined insects tobe knocked down when a defined weight of product is dispensedunder controlled conditions in a biological test chamber.

b) Percentage Kill - the percentage of the same or similar groups seento be dead after a defined period.

The formulation may be optimised such that:

1. The droplet size distribution is ideal for a space spray (sufficientlyline to remain airborne nevertheless allowing good impaction effi-ciency); or for a surface spray (sufficiently coarse to ensure gooddeposition). Due account has to be taken of the volatility characte-ristics of the droplets. Droplet size is measured by laser diffraction.This yields a measure of the complete distribution, as well as theconvenient volume median diameter (vmd).

2. The product delivers sufficient quantity of actives in the recommen-ded spraying time.

3. A mixture of ‘knock-down insecticide’ and ‘kill insecticide’ neces-sary in the formulation to achieve the required KT50 and percentageof kill.

AgrEvo Environmental Health has developed a complete standardrange of Detrans® concentrates for aerosols which are cost effectiveand meet the full requirements of the customer.

Concentrates are available for FIK, CIK, dual purpose aerosols andfor oil-based and water-based aerosols which cover a large range ofbiological performance at an optimised insecticide cost.

They can be described as follows:

Oil-Based Aerosols

Very High Quality Good Quality

FIK Detrans® 2780-A Detrans® 4274-ADetrans® 4283-A

CIK Detrans® 2788-A Detrans® 2649-ADetrans® 4281-A

MP Detrans® 4278-A

Water-Based Aerosols

Very High Quality

FIK Detrans® 2783-A

CIK Detrans® 4282-A

MP Detrans® 4280-A

To complement this standardoffer, AgrEvo EnvironmentalHealth is able, with the aid of aspecial computer programme topropose tailor-made formulae toaerosol manufactures, which willmeet specific requirements. Thisallows the design of the mostcost-effective combinations usedin FIK and CIK formulations.

Pyrethroid insecticides are addi-tionally optimised in respect ofsolvent/propellant blend andvalve/actuator selection.

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Solvents, Co-Solventsand Propellants

Solvents

The most frequently usedsolvents in Flying Insect Killerand Crawling Insect Killeraerosols are refined aliphatichydrocarbon mixtures, selectedso that their evaporationcharacteristics results in afavourable droplet size against atime profile for the aging spraycloud. Other compounds may beused , to control volatility, forexample in dual purposeformulations, or otherwise to actas a polar co-solvent for certainactive ingredients.Water may be used, as a diluent,to control flamma-bility informulations propel-led byflammable liquid propellants.

Propellants

Liquified or Liquid PropellantsA liquid propellant is one that caexist as a liquid in the formu-lation at a pressure which isbelow the safe maximum foraerosol containers, under normaltemperatures of operation.

Examples are:

CFCsCFCs are non-flammable propel-lants but are now rarely used inaerosols owing to their link withozone depletion.

HCsThe hydrocarbons, usually ablend of propane, iso-butaneand n-butane, of standardisedvapour pressure, are the mostcommonly used liquid propel-lants today. Derived from naturalgas they are plentiful and costeffective. A general term is aLPG, liquified petroleum gas.Hydrocarbon propellants may beused in the formulation of mostinsecticidal aerosols, providedspecial regard is given to flam-mability hazards during manu-facture and warehousing. Label

instructions are designedto eliminate risk to theend user. Water-in-oilemulsion type aero-solsmay be formulated,which have a reducedflammability.

HCFsNon-flammable blendsof HCFs are availablebut these have someozone depleting poten-tial and are regarded astransitional substances.

HFCsHFCs such as HFC134 tetrafluo-roethane, are non-flammableand non-ozone depleting, buttheir extremely high cost rendersthem currently unsuit-able forinsecticide aerosols.

Dimethyl Ether (DME)This liquid propellant has foundconsiderable application inEurope, Japan and to a lesserextent in the USA. Like hydro-carbon propellant it is highlyflammable, although a greaterconcentration in air is requiredbefore an ignitable mixture isobtained. A particular advantageof DME is that it is partiallymiscible with water, and byresort to water-miscible co-solvents, mainly aqueous singleliquid phase systems can beformulated which unlike ahydrocarbon emulsion do notrequire shaking before spraying.Disadvantages are that aqueoussolution systems are often corro-sive, and require special contai-ners or corrosion inhibitors.DME, unlike hydrocarbons, isnot a natural product, and has tobe synthesised. It ca therefore becomparatively expensive and isless freely available.

Compressed Gas PropellantsCompressed gas propellants arethose which, at normal tempera-tures, do not liquefy under pres-

sure or otherwise only undervery high pressures not suitablefor aerosol containers. Examplesof gases which may be used are:Carbon, Dioxide, Air, Nitrogenand Nitrous Oxide.Advantages of these compressedgas propellants include non-flammability and zero ozone-depleting potential. A seriousdrawback of compressed gaspropellants, there is much lessenergy available for atomisation,since there is only a smallreserve of propellants. Suchsystems are therefore generallyunsuitable for space spray appli-cations i. e. against flying insects.

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Multi-PurposeCrawling

Insect Killer

Market brief on chosen product

Source ofmanufacture?

Can type andpropellant?

Oil or Waterformulation?

Whatperfume?

What biological,chemical and

physicalcharacteristics?Existing plant

or contractmanufacturing?

New plant Registrationsearches

Valve andactuatorsystem?

Computer selection ofinsecticide formulation

Advice onequipment

Trade namechosen

Productsamples

Stabilitytesting

Made bycustomer

Made byAgrEvo

AgrEvobioassay

evaluation

Customerbioassay

evaluation

Customermarket

evaluation

Formulation chosen

Purchase ofequipment Registration dossier

prepared

Registration dossiersubmitted

Registration submissionsupported

Product registered

Continued productsupport

Total time 1 - 3 YearsDependant on

Registration RegulationsProduct launched

FlyingInsect Killer

I need an insecticide aerosol

Oil-Based Aerosols andWater-Based Aerosols

Oil-Based AerosolsOil-based aerosols are com-monly used for Flying InsectKiller aerosols throughout manyparts of the world. They havebeen found to be biologicallyefficient, easy to manufactureand offer an extended shelf life.In mar-kets where flammabilityor solvent odour may be acritical factor, water-basedaerosols are frequently found.

Water-Based AerosolsWater-based aerosols offer lowflammability in use characte-ristics, together with low irri-tancy. They also offer reducedorganic solvent usage and re-duced toxicity factors.Waterbased aerosols normallyoffer a shorter shelf life than oil-based products unless specialcontainers or lacquering is used.It can sometimes be difficult tomatch the bio-efficacy of oil-based system. Hydrocarbonemulsion products requireshaking before use. Water-basedproducts can normally be identi-fied by their wetter appearanceas a spray.

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It is obvious from the earlier sections that the formulation of agood quality insecticide aerosol is not straightforward.The difficulties are compounded by the ever increasing datarequirements of registration authorities.

AgrEvo Enviromental Health offers its customers a total servicebeginning with design, through to consumer testing, registra-tion support and launch of the final product.

The AgrEvo Offer -A Total Service to the Aerosol Industry

Design

AgrEvo Environmental Healthwill evolve a formulation thatwill meet the desired perform-ance against the targeted insectspecies in the most cost-effectivemanner. The formulation can bedesigned as an improvement onthe customer’s current product orbe a match or improvement onthe competition, or be specifi-

cally tailored to attack a newmarket niche. AgrEvo Environ-mental Health’s technical andmarketing staff are well qualifiedto assist in this selection. Theassistance offered covers thechoice of active ingredient,valve, propellant, solvent and allother aspects that will influencefinal performance.

Trial Formulation and Testing

As a first stage the AgrEvoEnvironmental Health computerprogramme is employed to assistin formulation selection. Oncompletion of the formulationsearch stage, trial samples ofthe product may be producedto enable the customer to con-cept test in his own marketplace.

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Registration

The registration of insecticides isbecoming increasingly complexthroughout the world. More dataare required today than everbefore.

AgrEvo Environmental Health isable to help aerosol manufac-tures by providing registrationfiles on active ingredients,manufacturing concentrates oreven on finished aerosols.

The AgrEvo EnvironmentalHealth database is frequentlyused to support customers’ regis-tration submissions.

If necessary, bioefficacy tests onthe proposed product may becarried out locally in our Frank-furt laboratories, where chemicaland physical analysis can also bedone. Our staff are then able toassemble the registration dossieron core products and submit it tothe regulatory body concerned.The progress of registrations isthen closely monitored so thatresponses to additional datarequests or other queries can beactioned without delay.

Few other companies in theworld can claim greater experi-ence in aerosol manufacture.

We maintain an unparalleledResearch and Developmentprogramme which providestechnological leadership in theaerosol field. A committedapproach to environmentalconsiderations is demonstratedby our pioneering work withsynthetic pyrethroids for aerosolformulations.

This approach allows AgrEvoEnvironmental Health to claim tooffer the most complete serviceto the aerosol industry.

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Hoechst Schering AgrEvo GmbHEnvironmental Health

D-65926 Frankfurt am Main, Germany

Telephone: ++49 (0) 69 - 305 - 8 44 87Telefax: ++49 (0) 69 - 305 - 1 75 56eMail: http://www.agrevo.com

For further information on allAgrEvo Environmental Healthproducts and services contact: or local: