Table 1.
Curing time, shear strength, and formaldehyde release of UF resins with different curing agents.
| Curing Agent Species | Curing Time | Shear Strength/MPa | Formaldehyde Emission/mg/L | ||
|---|---|---|---|---|---|
| Dry State | Surface Layer | Core Layer | |||
| Blank | >15 min | 1.04 | 0.54 | 0.22 | 1.08 |
| 1% NH4Cl | 2 min 45 s | 1.49 | 0.98 | 0.95 | 0.23 |
| 1% IPA | 3 min 10 s | 1.56 | 1.22 | 1.15 | 0.62 |
| 1% MA-HL | 6 min 42 s | 1.34 | 0.95 | 0.67 | 0.42 |
| 3% MA-HL | 3 min 56 s | 1.42 | 1.18 | 1.06 | 0.21 |
| 5% MA-HL | 2 min 50 s | 1.72 | 1.23 | 1.19 | 0.19 |
| 5% L | >15 min | 1.06 | 0.47 | 0.25 | 0.32 |
| Maleic acid | Gelling at room temperature in a few minutes | ||||