Key Properties
Chemical Name : Purified Isophthalic Acid
Abbreviation : PIA / IPA
CAS No. : 121-91-5
Molecular Formula : C₈H₆O₄
Molecular Weight : 166.13 g/mol
Appearance : White crystalline powder
Melting Point : 341–348 °C
Solubility : Very poorly soluble in water
Purity : ≥99% / ≥99.5% / ≥99.9%
Production : Oxidation of meta-xylene
Key Features
- Enhances corrosion resistance in resin systems
- Improves thermal stability and durability
- Provides higher mechanical strength vs phthalic-based systems
- Improves weatherability and UV resistance
- Reduces crystallinity in PET for better clarity and processing
Main Applications
Unsaturated Polyester Resins (UPR)
- Gel coats
- Marine FRP components
- Pultrusion & molded composites
PET Copolymer
- Bottle-grade PET
- Polyester fibers
- Improves transparency and flexibility
Coatings & Alkyd Resins
- Industrial coatings
- Automotive coatings
- Coil and marine coatings
High-Performance Materials
- Engineering plastics
- Aramid fibers (e.g. Nomex)
- High-temperature polymers
Production Process
Purified Isophthalic Acid (PIA) is produced by the liquid-phase catalytic oxidation of meta-xylene in the presence of oxygen.
- Catalyst system: cobalt–manganese
- Solvent: acetic acid
- Followed by crystallization and purification
- Final purity typically ≥99%
