Linseed oil (or other drying oils ) and other oil reactants ( i.e. castor oil) are heated with dry glycerol to 230-250 deg C with tin (II) oxylate catalyst to form the corresponding monoglyceride.
Ex: 50 g linseed oil with 30 g glycerol can be heated to form the monoglyceride. When 1g of the cooled heated mixture dissolves in 3 ml anhydrous methanol, the material is ready for resin formation. In step #2, 20 g phthalic anhydride is added to the reaction mixture which has been cooled to about 180 deg.C. 50 ml. xylenes are added to the mixture an a dean-stark trap is added to the reaction vessel and formed water is azeotroped off to completion (acid value reaches below 10 mg KOH/g resin).
The cooled oily resin is subjected to additional analysis and then mulled with pigment to form a relatively (compared to linseed oil) fast drying paint . I blend the formed paints , 1:1:, with synthetic petrolatums derived from renewables.
Otabr, Ifijen et al reported a convenient process to form the alkyd resins as described above.
Heliyon, 5, (2019) e1621 (open source).
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