Phosphorus Flame Retardant UPR (Non-Halogen)

Phosphorus Flame Retardant UPR is a halogen-free thermosetting resin that incorporates reactive phosphorus-containing monomers (typically phosphonate or phosphate esters) directly into the polyester backbone, supplemented by reactive phosphorus diluents in the styrene phase. This non-halogen approach meets the most stringent environmental and health requirements for closed compartment applications in rail, automotive, and building construction.

The phosphorus content (typically 1.5-3.0% P by weight) acts primarily in the condensed phase by promoting char formation, which physically insulates the underlying substrate from heat and oxygen. LOI of cured neat castings is 26-30%, and with ATH or magnesium hydroxide co-fillers, EN 45545-2 HL2 compliance is achievable for rail interior components.

Viscosity at 25°C is 350-650 mPa·s, suitable for hand lay-up, spray-up, and RTM. Cured flexural strength is 90-105 MPa. The absence of halogens eliminates toxic smoke gas generation concerns, making this the preferred choice for underground and enclosed transport infrastructure FRP applications.