Special solvents solvency

Agricultural Products. Pesticides are frequendy appHed as emulsiftable concentrates. The active insecticide or herbicide is dissolved in a hydrocarbon solvent which also contains an emulsifier. Hydrocarbon solvent selection is critical for this appHcation. It can seriously impact the efficacy of the formulation. The solvent should have adequate solvency for the pesticide, promote good dispersion when diluted with water, and have a dash point high enough to minimise dammabiUty ha2ards. When used in herbicide formulas, low solvent phytotoxicity is important to avoid crop damage. Hydrocarbon solvents used in post-harvest appHcation require special testing to ensure that polycycHc aromatics are absent. 

A kinetic treatment of these polymerization processes necessarily conriders the surface area of the latex particles rather than the latex particle volume, as is usually the case in emulsion polymmzation. Note that special cases of these polymerizations exist where a non-polymerizing solvent is added to change (normally increase) the solvency of the monomer in the latex particles, thereby modifying the polymer properties. 

Choice of resin is determined by the performance requirements of the adhesive, in terms of adhesive power, resistance and stability. The required evaporation rates depend on the application technique, which can vary from the rapid evaporation needed on a laminating machine to the slow drying necessary for manual brush applications. The major solvents employed are aromatic and aliphatic hydrocarbons (such as toluene, xylene and special boiling point aliphatics) and oxygenated solvents such as ethyl acetate, MEK and acetone. In many cases mixed solvent systems are used. Chlorinated solvents are found in some applications but their use is declining due to concerns over toxicity and environmental impact. Few alcohols are used in adhesives because they rarely have the solvency required to dissolve the resins. 

Glycol ethers are the solvents of choice for many application due to their excellent solvency, chemical stability, and water compatibility. Ethylene glycol methyl ether, EM, and ethylene glycol ethyl ether, EE, are used in specialized... 

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