ALKYD EMULSIONS

Various aspects of alkyd emulsion technology have been investigated. T he influence of alkyd oil length, acid value and hydroxyl number and t ype of surfactant used as emulsifier, on shear stability of alkyds emu lsions have been studied. It was found that the acid value was the mos t important alkyd parameter, the stability increasing with increasing oil length. It is also shown that anionic surfactants give emulsions w ith small droplet sizes at lower concentrations than do nonionics. Pol ymerizable nonionic surfactants have been tested as emulsifiers and co mpared with conventional surfactants of the same hydrophilic lipophili c balance (HLB). It was found that surfactants capable of participatin g in the autoxidative curing process give faster drying and improved f ilm hardness compared with nonreactive surfactants. The distribution o f driers between the alkyd phase and the water phase has been investig ated. It was found that low pH and the use of hydrophilic anionic surf actants, such as sodium dodecyl sulphate, favour partitioning of cobal t into the aqueous phase which is unfavourable with respect to drying properties.