Phthalic Anhydride

Phthalic Anhydride
What is it?

Phthalic Anhydride is a colourless solid at room temperature in the form of needles or platelets, with a monoclinic or rhombic crystalline structure. It was first discovered by Auguste Laurent in 1836 and became commercially available in 1872 through BASF.

The most important outlets for Phthalic Anhydride are phthalate plasticizers, unsaturated polyester resins and alkyd resins for surface coatings. Smaller volume applications of PA include polyester polyols, pigments, dyes, sweeteners and flame retardants.

Applications of Phthalic Anhydride

The primary use of Phthalic Anhydride is as a chemical intermediate in the production of plastics from Polyvinyl Chloride. It is the main component in the production of phthalate esters, which function as plasticizers to increase the flexibility, transparency, durability and longevity of plastics. Derivatives of Phthalic Anhydride are thus commonly found in products such as cables, pipes, hoses, shoes, film for packaging, coated fabrics etc.

The second largest outlet for Phthalic Anhydride is in the production of Unsaturated Polyester Resins (UPR), which are usually blended with glass fibres to produce fiberglass-reinforced plastics. Principal industries include construction, furniture moulding, marine and transportation.

The third major use of Phthalic Anhydride is in the production of Alkyd Resins. These are used as solvent-based coatings for architectural, machinery, furniture and fixture applications.

There are also minor but growing sectors for phthalic anhydride use, such as in polyester polyols and flame retardants.