Emulsifiable concentrates (EC) have for several years been a popular class for the formulation of crop protection products and despite concerns over specific drawbacks EC’s remain one of the most popular formulation classes. With the active ingredient dissolved in a suitable solvent emulsifiers are added to provide a spontaneous stable emulsion on addition to water with a typical particle size in the range 0.1-10 μm.
The spontaneous stable emulsions are obtained by selecting the optimum combination of surfactants that have the correct HLB for the active solvent mixture, typically a mixture of an anionic and nonionic surfactant. This provides a spontaneous stable emulsion, which, when sprayed, gives a uniformed application with accurate control of the application level to the crop. The careful selection of the surfactants used can also aid the activity of the crop protection product by increasing wetting and facilitating the transfer of the active material into the plant tissue.
A typical emulsifiable concentrate contains the following components:
Active ingredients | 5 - 60% |
Anionic emulsifier | 2 - 7% |
Nonionic emulsifier | 2 - 7% |
Solvent | 25 - 90% |
Stabiliser | 0 - 3% |
The advantages of emulsifiable concentrates include:
Spontaneous emulsification providing uniformed dispersion into the spray tank.
Good biological activity
Good chemical stability of the formulation
Ease of manufacture
Emulsifiable concentrates have a number of issues, most of which relate to the use of a solvent, some of which can be minimised by careful solvent selection. Issues include:
Emissions of VOC’s
Solvents can adversely affect spray equipment components
Potential of greater operator exposure
Flammability
Lankem offers a range of emulsifiers for use in the formulation of emulsifiable concentrates. These fall into three main categories:
Anionic emulsifiers
Nonionic emulsifiers
Formulated / Balanced pair emulsifiers
The careful selection and formulation of the emulsifier system can provide optimum characteristics in terms of emulsion spontaneity and stability over a range of water qualities and temperatures, this is achieved by using a combination of an anionic and nonionic emulsifier. Lankem has the following product offer of emulsifiers and formulation aids.
Anionic Emulsifiers
Kemsurf CA and Kemsurf CA-EH, these materials are highly active calcium salts of alkylbenzene sulfonates dissolved in solvent and are the most widely used anionic emulsifier used in emulsifiable concentrates, providing excellent emulsification of a wide range of solvent and are particularly effective for systems based on aromatic solvents. The two products have similar properties with Kemsurf CA-EH having a higher flash point.
Kemsurf PWS, this material is a neutralised alkylbenzene sulphonate. It provides excellent emulsification characteristics particularly for aliphatic solvents.
Nonionic Emulsifier
Agrosurf NEC15T, highly effective polyaromatic based ethoxylate, typically used in combination with an anionic emulsifier such as Kemsurf CA or Kemsurf CA-EH, but can be used alone for certain aromatic solvent based formulations, providing excellent emulsion spontaneity and stability.
Agrosurf NEC12 and Agrosurf NEC40, Castor oil ethoxylates, typically used in combination with an anionic emulsifier such as Kemsurf CA or Kemsurf CA-EH, effective emulsifiers for a broad range of emulsifiable concentrate formulations, good candidates for systems based on ester and amide solvent based formulations.
Balance Pair Emulsifier
Agrosurf BPE148 and Agrosurf BPE211, Agrosurf BPE148-EH and Agrosurf BPE211-EH are anionic/nonionic balanced pair emulsifiers that have been specifically developed to allow the formulation of a wide range of active ingredients in different solvents. The benefit of using balanced pair emulsifiers includes reductions in the number of emulsifiers needing to be handled and greater robustness of formulation performance.
Formulation Aides
Agrosurf GF, epoxidized vegetable oil used to increase the storage stability of emulsifiable concentrates by reacting with water and/or acidic species that can lead to the chemical degradation of active ingredients.
Agrosurf COS4, acts as a cosolvent helping to increase the solubility of active ingredients into a range of hydrocarbon solvents. The material is VOC free and non-flammable.