Over half the production of phthalic anhydride is used in the manufacture of phthalate esters, employed as plasticisers in PVC. Other major uses are in polyester resins and (decreasingly) in alkyd resins. About 10% of phthalic anhydride production is used in the production of isatoic anhydride and chemical feedstock.
The major end use of phthalate esthers is in the construction and transportation industries. Alkyd resins containing PA are used in solvent-borne protective coatings. As paint technology increasingly utilises water-borne technologies, many PA-based alkyds have lost out to alternative raw materials.
Other minor uses are in the manufacture of dyes, magnesium peroxyphthalate for detergents, rubber retarder, scorch inhibitor for rubber stocks, hardener for resins, synthesis of phenolphthalein and other phthaleins, curing agent for epoxy resins, fire retardants, polyester resin cross-linking agents and drying oil modifiers.
PA can irritate the skin, throat and eyes.
To find out more Phthalic Anhydride Methodology July 2013