PMA

What it is

PMA (also called PGMEA or methoxypropyl acetate) is the acetate ester of propylene glycol methyl ether (molecular weight 132.16 g/mol). It is a colorless liquid with a mild, fruity odor, a boiling point of about 146 °C and a flash point of about 42–45 °C.

Role in coatings

PMA is used in 2K polyurethane, acrylic, epoxy, polyester and nitrocellulose coatings for automotive, industrial, coil and wood finishing, and as a photoresist solvent in electronics. Its slower evaporation improves flow and leveling and helps release trapped solvent before the film skins over.

Chemistry & key properties

• No reactive hydrogens: unlike its parent ether, PM (1-methoxy-2-propanol), PMA has no hydroxyl group, so dry grades are suitable for isocyanate systems.
• Polarity: the ether and ester groups dissolve a wide range of polar resins.
• Evaporation: slower than xylene, so it is used as a tail solvent for flow and gloss.
• Isomers: commercial PMA is mainly the alpha isomer; specifications limit the beta isomer, which is classified as a reproductive toxicant.

Handling & storage

PMA is a flammable liquid that may cause drowsiness or dizziness at high vapor concentrations. Use ventilation, keep away from ignition sources and ground containers. Store sealed and dry; in polyurethane work, water pickup makes it unsuitable as a urethane-grade solvent.