Is the dominance of bromine-based flame retardants being shaken? Organophosphorus and nitrogen-based flame retardants are rising strongly.
(I) Brominated Flame Retardants – Once the “Dominant Force,” Now a “Controversial Player”
Brominated flame retardants dominated the market for decades due to their high flame retardant efficiency and cost-effectiveness. However, under environmental pressure, they are developing towards higher molecular weight and reactive formulations.
Decabromodiphenyl ethane (DBDPE): An ideal substitute for decabromodiphenyl ether, as it does not produce dioxins.
Decabromodiphenyl ether (DBDPO): A traditional mainstay, but banned in many countries due to environmental concerns.
Tetrabromobisphenol A (TBBPA): Can be used as an additive or as a reactive agent (for the synthesis of brominated epoxides and polycarbonates).
Brominated polystyrene (BPS): A high molecular weight flame retardant with high thermal stability, suitable for nylon and PBT.
Tribromophenol and its derivatives: Reactive intermediates used for end-capping brominated epoxides and the synthesis of bromotriazines, etc.
Triazine Bromodiphenyl ether (TTBPC): Bromine-nitrogen synergy, high thermal stability (>330℃), used in ABS and HIPS.
Brominated Epoxy Resin (BEO): EP type and EC type, used in copper clad laminates and engineering plastics, respectively.
Hexabromocyclododecane (HBCD): Once widely used in EPS/XPS insulation boards, now banned; China discontinued its use at the end of 2021.
Octabromoether and Methyloctabromoether: Octabromoether is used in PP/PE, while methyloctabromoether is used as an HBCD substitute in XPS.
Brominated SBS: High molecular weight, good compatibility with polystyrene, a new alternative to HBCD.
Tetrabromobisphenol A Polycarbonate Oligomers (BC-52/BC-58): Macromolecular flame retardants with excellent thermal stability.
Declolon (DCRP): Chlorine-based flame retardant, its use is restricted due to its persistent organic pollutant properties.
(II) Organophosphorus Flame Retardants – The Main Force in Halogen-Free Flame Retardants
Organophosphorus flame retardants function simultaneously in the gas phase (PO· free radical quenching) and the condensed phase (char formation), representing an important alternative to bromine-based flame retardants.
Phosphate Esters: Including TPP, BDP, RDP, TCPP, TCEP, etc.
BDP and RDP are used in engineering plastics such as PC/ABS and PPO/HIPS; TCPP and TCEP are used in polyurethane foams.
DOPO and its derivatives: DOPO can react with various compounds through P-H bonds, achieving inherent flame retardancy in epoxy resins and polyesters. Derivatives such as ODOPB and TAD have wide applications.
Alkyl Phosphinates (e.g., aluminum diethylphosphinate, ADP): Extremely high thermal stability (>400℃), suitable for nylon and polyesters, with even better synergistic effects when combined with MPP.
Cage Phosphate Esters (PEPA, Trimer): Single-component intumescent flame retardants with high thermal stability and good char formation.
Phosphazene (Hexaphenoxycyclotriphosphazene, HPCTP): A phosphorus-nitrogen heterocyclic structure with high thermal stability, used in epoxy, PC/ABS, etc.
(III) Nitrogen-based Flame Retardants – Environmentally Friendly and Low-Toxicity "Fresh and Clean" Approach
Melamine Cyanurate (MCA): Primarily used in PA6 and PBT, it exerts its flame-retardant effect through sublimation endothermic reaction and gas dilution, while also providing anti-dripping properties.
Melamine Phosphate (MP): A synergistic effect of phosphorus and nitrogen, suitable for polyolefins and coatings.
Charring Agents (Triazine, Piperazine): Blended with APP to form intumescent flame-retardant systems, such as triazine charring agents and piperazine pyrophosphate.
