Polyoxyalkylene polyol esters

The addition of ethylene oxide to sorbitan esters raises the HLB of the resultant ester products. Thus, ethoxylation of sorbitan monolaurate with 4 mol of ethylene oxide per mole of ester will raise the HLB value from 8.3 to 13.3. Values for different sorbitan esters are given in Table 5.10. 

By analogy with the polysorbate ester reaction, similar surfactant ester feedstocks that feature a free hydroxyl function can undergo oxyethylation to materials of higher HLB and these include glycerol, polyglycol and sucrose esters. In addition, many naturally occurring fats and oils can react with ethylene oxide to raise their water solubility. Castor oil is a common base for oxyethylation and the obvious site is the hydroxyl group in the ricinoleic 

Common products available commercially are castor oil plus 30- or 45 mol ethylene oxide, which are very effective emulsifiers. 

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Miscellaneous Commercial Applications. Dimer acids are components of "downweU" corrosion inhibitors for oil-drilling equipment (see Petroleum Corrosion and corrosion inhibitors). This may account for 10% of current dimer acid use (71). The acids, alkyl esters, and polyoxyalkylene dimer esters are used commercially as components of metal-working lubricants (see Lubrication). Dimer esters have achieved some use in specialty lubricant appHcations such as gear oils and compressor lubricants. The dimer esters, compared to dibasic acid esters, polyol esters and poly(a-olefin)s, are higher in cost and of higher viscosity. The higher viscosity, however, is an advantage in some specialties, and the dimer esters are very stable thermally and can be made quite oxidatively stable by choice of proper additives. 

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