Paper honeycomb fire doors—typically constructed with steel or composite faces—generally target fire endurance ratings of 20 to 60 minutes (reaching up to 90 minutes in specialized designs utilizing flame-retardant treated paper cores). In standard fire furnace testing, the bond line between the face sheet and the core bears intense thermal shear and positive-pressure furnace draft, making adhesive selection critical.
| Adhesive Chemistry | Fire Rating | Key Advantages & Process Fit | Limitations |
| 1K Moisture-Cure PUR | 20 – 45 min | Ready-to-use, micro-foaming properties fill honeycomb margins, high water resistance, solid thermal durability. | Thermally degrades above 60 minutes without core insulation or FR additives. |
| 2K Polyurethane (2K PUR) | 45 – 60 min | Controllable pot life, elevated crosslink density, superior high-temperature shear resistance, suited for high-speed lamination. | Requires dual-component meter-mix equipment; sensitive open time. |
| Inorganic Adhesive (Silicate / MGO-based) | 60 – 90+ min | Non-combustible (Class A1), withstands temperatures exceeding 1000°C. | Extremely brittle, poor impact/flex resistance, susceptible to efflorescence or moisture damage over time. |
| FR-Modified Epoxy | 30 – 60 min | Exceptional structural strength, excellent adhesion to untreated metals, negligible curing shrinkage. | Higher cost, rigid cured matrix, high working viscosity. |
Contact Easybond Specific Adhesive Limited
