| 1 | Polyamidoamine | Amine-terminated fatty-acid polyamide reacting with epoxy groups | 90–150 | 10–25°C | Medium to long | Good | Generally good adhesion and flexibility; useful where substrate movement and impact resistance are important. | Provides forgiving ambient curing and good tolerance of less-than-ideal surface conditions, but may cure slowly at low temperature and can show amine blush in humid conditions. |
| 2 | Modified Aliphatic Amine | Primary or secondary aliphatic amines, often modified to control reactivity and blush | 25–60 | 5–15°C | Short to medium | Moderate to good | Usually provides strong early adhesion and rapid hardness development on steel and other prepared metals. | High reactivity improves low-temperature cure, but excessive concentration can shorten working time, increase exotherm, and reduce flexibility. |
| 3 | Cycloaliphatic Amine | Cyclic aliphatic diamines or polyamines with relatively rigid structures | 45–80 | 10–25°C | Medium | Good | Can deliver a hard, chemically resistant network with strong adhesion when the metal surface is properly prepared. | Balances ambient cure and final performance; formulation control is needed to limit brittleness and surface haze. |
| 4 | Amine Adduct | Pre-reacted epoxy–amine adduct containing residual amine functionality | 70–140 | 5–20°C | Medium | Good | Often improves compatibility, mixing behavior, and adhesion consistency compared with unmodified amines. | The pre-reacted structure can reduce volatility and improve blush resistance, while the selected adduct controls cure speed and film hardness. |
| 5 | Phenalkamine | Cardanol-derived phenolic structure combined with amine functionality | 100–180 | 0–10°C | Medium to long | Very good | Frequently selected for damp or cool environments because it can maintain adhesion and cure development under challenging conditions. | Supports low-temperature curing, good water resistance, and rapid return to service; odor, color, and recoat-window requirements should be evaluated. |
| 6 | Polyetheramine | Amine-terminated polyether chains with flexible ether segments | 60–250 | 10–25°C | Medium to long | Moderate | Improves flexibility, impact resistance, and wet adhesion, although excessive flexibility may reduce hardness and barrier performance. | Useful for reducing brittleness and accommodating thermal or mechanical movement; cure speed depends strongly on molecular weight and amine functionality. |
| 7 | Aromatic Amine | Aromatic diamines or polyamines with low-mobility aromatic segments | 45–75 | 60–120°C | Long at room temperature | Good after heat cure | Produces high glass-transition temperature, chemical resistance, and durable adhesion after elevated-temperature curing. | Suitable for heat-cured primers requiring high thermal and chemical resistance; limited for field application without controlled heating. |
| 8 | Dicyandiamide | Latent nitrogen-containing curing agent for epoxy resins | Approximately 21 based on active hydrogen; practical formulation values vary | 140–180°C | Very long before activation | Good in storage; limited before full cure | Can provide hard, chemically resistant films with strong adhesion after complete thermal cure. | Excellent for one-component or heat-activated systems; accelerator selection and dispersion are critical for achieving complete conversion. |
| 9 | Acid Anhydride | Cyclic or polymeric anhydride groups reacting with epoxy resins, usually with an accelerator | 160–210 | 80–140°C | Long before heating | Sensitive to moisture before cure | Forms low-shrinkage, high-temperature-resistant networks with good electrical and dimensional properties. | Requires controlled thermal processing and careful moisture control; often chosen when low color and high heat resistance are priorities. |
| 10 | Ketimine | Blocked or latent amine that hydrolyzes in the presence of moisture and releases reactive amine groups | 70–160 effective range, depending on structure and formulation | 5–25°C with available moisture | Long in dry storage; activated after application | Requires atmospheric or formulation moisture | Useful for moisture-triggered curing and improved package stability; final barrier performance depends on complete hydrolysis and epoxy conversion. | Can extend shelf life and reduce premature reaction in one-component systems, but curing may be slow in dry environments or thick, moisture-isolated films. |
