Phthalic Anhydride


Phthalic anhydride (P.A.) is the cornerstone of Stepan’s vertically integrated Polymers division. The phthalic anhydride plant is an integral part of the ISO 9001:2015 Stepan Millsdale site, located in Elwood, Illinois. P.A. is manufactured at this site to supply the internal requirements of the STEPANPOL® polyester polyols product line.  In addition, Stepan is a major P.A. supplier to the North American merchant market.

End Use Markets

  • Polyester resins
  • Plasticizers
  • Alkyd resin and coatings 
  • Polyester polyols
  • Pigments and dyes
  • Engineered plastics
  • Flame retardants

Common Uses and Applications

  • Boat hulls
  • Shower stalls
  • Flexible tubing and containers in the medical industry
  • Wire coating and insulation
  • Garden hoses
  • Commercial and residential paint coatings
  • Vinyl wallpaper

See all Stepan phthalic andydride products.