Patent attributes
Mixtures of isomeric dialkyl phthalates that have a desired viscosity are prepared by esterifying phthalic acid or phthalic anhydride with a mixture of isomeric alkyl alcohols having a certain carbon number of carbon atoms, where the molar fraction of each alkyl alcohol isomer of the isomeric alcohol mixture is determined, and where the viscosity parameter of each alkyl alcohol isomer of the alcohol mixture, which, upon reacting with phthalic acid or phthalic anhydride, results in a mixed isomer dialkyl phalate ester product having a specific desired viscosity, is determined in accordance with formula (I):ln(η)=Σχi*ln(ηi) (I)where η=the calculated viscosity of a dialkyl phthalate mixture,χi=the molar fraction of an isomerically pure alcohol (i), andηi=the viscosity parameter of isomerically pure alcohol (i).
