Components for Emulsion Polymers

The basic components of an acrylic latex polymer system are  

In addition to the above components such as plasticisers and coalescing solvents are added when the coating is prepared, to improve film forming and film performance characteristics. 

The quality of the water used in emulsion polymerisation is important. The presence of polyvalent metal ions can cause instability. De-ionised water is preferred for the process, and usually a limit of 250,000 ohm resistance is placed on the water used. Commercial processes are conducted with a water composition of between 35 and 65% of the total reaction charge and more frequently of the order of40-50%. 

Most acrylic monomers will undo go emulsion polymerisation, although the monomer molecules must be available in a solubilised state, either in the form of surfactant stabilised droplets or in micelles. Where the acrylic monomer contains a long chain alkyl group (e.g. lauiyl and stearyl acrylates and methacrylates) polymerisation may be retarded by steiic factors resulting in low degrees of conversion of the monomer. 

The rate of slow reactions can often be improved by the addition of a small amount of water soluble solvent (e.g. glycols, alcohols or ketones) to the aqueous phase to improve the emulsification and hence, the availability of the monomer for reaction. 

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