With growing concerns about environmental impact and toxicity, halogen-free flame retardants (HFFRs) have emerged as critical alternatives to traditional brominated/chlorinated systems.

Why Choose Halogen-Free?

Halogen-free flame retardants avoid bromine/chlorine while providing:

  • Reduced toxic fume emission during fires
  • Better recyclability of treated materials
  • Compliance with strict regulations (e.g., EU RoHS, REACH)
  • Lower bioaccumulation risks

Key Halogen-Free Flame Retardant Materials

1. Phosphorus-Based Compounds

  • Types:
    • Organic: Resorcinol bis(diphenyl phosphate) (RDP)
    • Inorganic: Red phosphorus, ammonium polyphosphate (APP)
  • Mechanism: Forms insulating char layer through dehydration reactions
  • Applications: Epoxy resins, polyurethane foams

2. Nitrogen-Based Systems

  • Examples: Melamine cyanurate, guanidine sulfamate
  • Action: Releases inert gases (NH₃, N₂) to dilute flammable vapors
  • Efficiency: Often combined with phosphorus for synergy

3. Mineral Fillers

Material Activation Temp. Key Feature
Aluminum Hydroxide 200-300°C Smoke suppression
Magnesium Hydroxide 300-340°C Higher thermal stability
Huntite/Hydromagnesite 220-550°C Self-charing properties

Usage: 50-65% loading in cables, rubber products

Halogen-Free Flame Retardants

4. Silicon-Based Additives

  • Forms: Silicones, silica nanoparticles, silsesquioxanes
  • Advantage: Enhances thermal stability without heavy metal content

Performance Comparison: Halogen vs. Halogen-Free

Parameter Halogen-Based Halogen-Free
Toxicity High (dioxins) Low
Smoke Density High Moderate
Processing Temp <200°C 200-350°C
LOI* Improvement 22-28 24-32

*Limiting Oxygen Index

External References:

  1. Halogen-Free Flame Retardant Bopet Film Market Forecast
  2. Novel Greener Routes To Halogen-Free Flame Retardant Materials