N-Methyl-2-Pyrrolidone (NMP, Low VOC Process Solvent)
CAS 872-50-4N-Methyl-2-Pyrrolidone (NMP, CAS 872-50-4) is a high-boiling, aprotic polar solvent with exceptional solvency for a wide range of polymer systems including polyamide, polyimide, epoxy, polyurethane, and acrylic resins.
Key Features
- ✓Very high boiling point (202°C) and low vapor pressure — minimal evaporation, low ambient VOC
- ✓Exceptional solvency for cured epoxy, polyimide, polyurethane — DCM-free stripping alternative
- ✓Reproductive toxicant (EU Repr. 1B) — requires strict exposure control and PPE
- ✓High flash point (91°C) — much lower flammability hazard than ketone or aromatic solvents
- ✓Must be removed by elevated temperature drying when used as composite process solvent
Specifications
| Parameter | Value |
|---|---|
| Purity | ≥99.5% by GC |
| Appearance | Clear, colorless to pale yellow liquid |
| CAS Number | 872-50-4 |
| Flash point | 91°C (ASTM D93) |
| Boiling point | 202°C |
| Density (20°C) | 1.028 g/cm³ |
| Water miscibility | Fully miscible |
| Vapor pressure (20°C) | 0.04 kPa (very low) |
FAQ
NMP-based strippers work differently from DCM: DCM rapidly swells and dissolves the cured epoxy network within minutes due to its very high Kauri-Butanol value, while NMP relies on polymer diffusion and swelling over an extended contact time (typically 1–6 hours, sometimes requiring heat at 40–60°C for hard-cured systems). Commercial NMP-benzyl alcohol blended strippers are formulated to optimize this penetration and swelling process. The procedure typically involves: (1) Apply NMP stripper liberally to the coating, cover with plastic film to prevent evaporation; (2) Allow 1–4 hours soak time (longer for thick coatings or hard cure); (3) Test for softening — the coating should become blistered or soft enough to scrape; (4) Remove with plastic scraper; (5) Rinse with water (NMP is fully water-miscible). While slower than DCM, NMP strippers achieve equivalent results on most epoxy and polyurethane coatings and are the compliant choice where DCM is restricted.