Glycol Ethers, High-Purity Solvents

Propylene Glycol Monomethyl Ether Acetate (PMA)

Propylene Glycol Monomethyl Ether Acetate (PMA), also known as PGMEA or 1-methoxy-2-propanol acetate, is a high-performance, slow-to-medium evaporating solvent. It is a clear, colorless, and hygroscopic liquid with a mild, ether-like odor. Belonging to the P-series glycol ether family, PMA was developed as a safer, lower-toxicity alternative to ethylene glycol-based ethers (E-series), which were largely phased out due to reproductive health concerns.

PMA is synthesized through the esterification of propylene glycol monomethyl ether with acetic acid. Its unique molecular structure, featuring both ether and ester functional groups, provides it with exceptional solvency power for a wide range of synthetic resins, including acrylics, epoxies, alkyds, and polyesters. In the high-tech sector, PMA is the “gold standard” solvent for the microelectronics industry, specifically used in photolithography. Its high purity and ability to dissolve photoresists make it indispensable for semiconductor fabrication. Its balanced evaporation rate ensures superior film formation and surface leveling in high-end coating applications.

Attributes

Key Features and Benefits

Superior Solvency: Exhibits high solvency for various polymers, resins, and oils, making it a versatile coupling agent and carrier.
Controlled Evaporation: The moderate evaporation rate allows for excellent flow and leveling, preventing surface defects like blushing or “orange peel.”
Low Toxicity: Offers a significantly improved toxicological profile compared to E-series glycol ether acetates (e.g., EEA).
Coalescing Efficiency: Acts as a powerful coalescent in solvent-borne coatings, facilitating high-quality film integrity at lower temperatures.
Hydrophobic Character: While partially soluble in water, its acetate group increases hydrophobicity compared to its parent glycol ether, improving moisture resistance in films.
Versatile Compatibility: Miscible with most common organic solvents, enhancing formulation flexibility.

Specifications

Technical Highlights

Chemical Formula: C₆H₁₂O₃ (CAS No. 108-65-6).
Molecular Weight: 132.16 g/mol.
Boiling Point: 146°C (295°F) at 760 mmHg.
Flash Point: 42°C – 45°C (107°F – 113°F) (Tag Closed Cup), classifying it as a Flammable Liquid (Class 3).
Specific Gravity: 0.965 – 0.970 at 20°C.
Vapor Pressure: Approximately 3.7 mmHg at 20°C.
Viscosity: 1.1 cP at 25°C, providing low-viscosity solutions even at high solids content.
Purity Grades: Available in Industrial Grade (99.5% min) and Electronic Grade (99.9% min) with ultra-low metal ion content (ppb levels).
Hansen Solubility Parameters: δ_d (16.1), δ_p (6.1), δ_h (6.6).