METHYLAL IN AEROSOL INSECTICIDES

Household and professional insecticides represent an important market for the aerosol industry because of the efficiency, the convenience and the quick action of these products.

Nevertheless, various changes occurred in the formulation ways due to legal restrictions on the use of :

• active ingredients (DDT, Lindane, DDVP, ...),
• solvents (Tri III, methylene chloride, ...)
• and propellants (CFC 11 / 12, 22, ...).

Due to these changes, the activity and efficiency were reduced.

METHYLAL is the answer to these problems, offering

• an improved biological activity
  
  
• low toxicity
  
  
• low VOC and GWP
  
  
• reasonable cost
  
  
• smaller spray particles
  
  
• flammability reduction
  
  
  • through the possible use of non-flammable propellants (CO₂, N₂) and pumps
  • through single phase water-based formulations
    

BIOLOGICAL EFFICIENCY

We have made 3 formulations with the reference I 26 and compared their biological efficiency on house flies and on mosquitoes.

Ingredients (% weight)	I 26 a	I 26 b	I 26 c
Bioallethrine Tetramethrine Permethrine Piperonyl Butoxyde Methylal Isopar C Propane-butane 3.2 Bar	0.075 0.25 0.075 0.75 38.85 0 60	0.075 0.25 0.075 0.75 0 38.85 60	0.075 0.25 0.075 0.75 19.42 19.42 60

a) Test on 800 house flies

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b) Test on mosquitoes

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WHY WOULD METHYLAL INCRASE THE EFFICIENCY ?

a) Particle size reduction

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There is a controversy on the ideal particle size for insecticides : 20 or 8.5 microns are estimated to be optimal, but generally it is estimated that a 20 micron particle falls on the floor in 5 minutes ... which would give only a short action time to a spray for flying insects.

Methylal reduces the particle size.

Example in a pump spray :  

Methylal improves the homogeneity of the spray : narrower fork, smaller difference between thin and big particles, making the active proportion of the erogated product more important.

b) Amphiphilic character of methylal

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Methylal is both lipophilic and hydrophilic. It consequently helps the penetration of a hydrorepellent insect secretion by water-based actives.

FLAMABILITY

Methylal is miscible with water and makes it possible to formulate single phase water-based insecticides with DME, CO₂ or even nitrogen.

With CO₂, the exceptional Bunsen value of 9.5 (ethanol 2.9 - water 0.85) methylal gives extraordinary good spray qualities all along the can life.

Drum test :

The flammability characteristics of airfreshener formulations are very similar to those of insecticide formulations. Drums tests on insecticides will be done in the near future.



FORMULATION GUIDELINES

Insecticides

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I 4 I 10 I 14 I 26 I 32

Insecticide CO2 propelled water based Insecticide DME propelled Water based Insecticide CO2 propelled water based Insecticide propane-butane propelled Insecticide CO2 propelled