Isophthalic acid

Isophthalic acid (CAS 121-91-5), commonly abbreviated as IPA in the polymer and coatings industry, is an aromatic dicarboxylic acid used as a monomer and polymer modifier. It introduces flexibility and improved chemical resistance.

This chemical reduces crystallinity into polyester and resin systems compared to its terephthalic acid counterpart. Procurement teams source it primarily as a building block for performance resins, coatings, and engineering polymers.

In unsaturated polyester resins, IPA produces formulations with superior corrosion resistance. This makes it a preferred monomer for fiberglass-reinforced tanks, pipes, and marine composites used in heavy industrial applications.

Coatings manufacturers incorporate it into alkyd and polyester resins to improve adhesion, gloss retention, and durability. These enhancements are vital for both industrial and architectural finishes requiring long-term stability.

PET modification is another major outlet where partial substitution of terephthalic acid with IPA reduces crystallization rate. This enables clearer, more processable packaging materials and specialty films for the consumer market.

In adhesives and powder coatings, it functions as a crosslinking co-monomer that controls cure behavior. This specific chemical interaction improves end-product flexibility and overall performance in demanding environments.

Isophthalic acid is supplied as a white crystalline powder or free-flowing granules. Standard commercial grades include technical and polymer-grade specifications with purity levels typically at 99% or higher to meet requirements.

Packaging ranges from 25 kg bags to bulk containers, with fiber drums common for industrial quantities. These formats ensure the material remains stable and free-flowing during transport and storage for global supply chains.