Analysis of the main Components of Organic Low Smoke Zero Halogen Flame Retardants
Organic low smoke zero halogen flame retardants take phosphorus, nitrogen, silicon and other elements as core flame retardant components. They achieve efficient flame retardancy through chemical synergy and meet the environmental protection requirements of low smoke and zero halogen at the same time. The following is an analysis from the aspects of component classification, typical substances and flame retardant mechanisms:
——————————————————————————–
First, phosphorus-based flame retardants
Core components: Phosphate esters, phosphonate esters, organophosphorus salts, phosphorus heterocyclic compounds and polymer phosphonate (phosphonate) esters
Mechanism of action:
Gas-phase flame retardancy: At high temperatures, it decomposes to form phosphoric acid (H₃PO₄), capturing free radicals (such as ·H, ·OH) in the combustion chain reaction and interrupting the combustion process.
Solid-phase flame retardancy: Promotes the formation of a carbonized layer on the material surface, isolating the transfer of oxygen and heat.
Typical applications:
Phosphate esters: such as triphenylphosphate (TPP), are widely used in engineering plastics like PC and ABS.
Phosphonate esters: such as bisphenol A bis (diphenylphosphate) (BDP), which have high thermal stability and hydrolytic stability, are suitable for PC/ABS alloys.
Phosphorus heterocyclic compounds: such as 9, 10-dihydro-9-oxa-10-phosphoafine-10-oxide (DOPO), used in epoxy resins and polyurethanes.
——————————————————————————–
Second, nitrogen-based flame retardants
Core ingredients: Melamine, melamine cyanurate (MCA), dicyandiamide, urea
Mechanism of action:
Gas-phase flame retardancy: When heated, it decomposes to produce inert gases such as ammonia (NH₃), diluting the concentration of oxygen.
Synergistic effect: When compounded with phosphorus-based flame retardants, the flame retardant efficiency is significantly enhanced through the P-N synergistic effect.
Typical applications:
MCA: It is often used in nylon materials such as PA and PBT. An addition amount of 15%-20% can reach UL94 V-0 grade.
Melamine: When compounded with ammonium polyphosphate (APP), it forms an intumescent flame retardant system, which is suitable for polyolefin materials.
——————————————————————————–
Third, silicon-based flame retardants
Core components: Silicone resin, polysiloxane, silicate (such as montmorillonite)
Mechanism of action:
Physical barrier: A dense layer of silicon carbide is formed during combustion, which isolates heat and oxygen.
Dilution effect: Releases non-flammable gases such as water vapor to reduce the concentration of flammable gases.
Typical applications:
Polysiloxane: such as silicone rubber and silicone oil, is used in high-temperature flame-retardant materials.
Nano-silicates: such as montmorillonite, enhance flame retardancy through nano-intercalation technology.
——————————————————————————–
Fourth, intumescent Flame Retardant System (IFR)
Core components: Acid source (such as ammonium polyphosphate APP), carbon source (such as pentaerythritol PER), gas source (such as melamine MEL)
Mechanism of action:
Expansion carbonization: When heated, the acid source decomposes to form phosphoric acid, which catalyzes the dehydration of the carbon source into carbon. The gas source releases gas, causing the carbon layer to expand.
Synergistic flame retardancy: Forms a porous carbon layer, isolates oxygen and heat, and simultaneously inhibits smoke generation.
Typical applications:
APP/PER/MEL system: Widely used in polyolefin materials such as PP and PE, with an addition amount of 20%-30%, it can reach UL94 V-0 grade.
——————————————————————————–
Fifth, phosphorus-nitrogen co-flame retardants
Core components: Organic compounds containing phosphorus and nitrogen (such as phosphoronitrile compounds, phosphoramide)
Mechanism of action:
P-N synergistic effect: Phosphorus promotes carbon formation, and nitrogen releases inert gases. The two work together to enhance the flame retardant effect.
Low smoke and halogen-free: When burning, it generates phosphate and nitrogen oxides, without toxic gases such as hydrogen halide.
Typical applications:
Phosphorus nitrile compounds: such as hexachlorocyclotriphosphorus nitrile derivatives, used in high-temperature materials like PC and PPO.
Phosphoramide: such as N,N’ -bis (diphenylphosphoacyl) hexamethylenediamine, suitable for epoxy resins and polyurethanes.
——————————————————————————–
——————————————————————————–
Sixth, application fields and advantages
Wires and cables: Low smoke zero halogen flame retardants ensure the release of non-toxic smoke during a fire, in compliance with the IEC 60332 standard.
Electronic and electrical appliances: Enhance the flame retardant grade of materials (UL94 V-0) to ensure the safety of equipment.
Building materials: Used for fireproof boards and insulation materials, meeting the A-level fire protection requirements.
Transportation: In the interior materials of automobiles and high-speed railways, reduce the risk of fire spread.
Advantages:
Environmental friendliness: Halogen-free, low smoke, non-toxic, and complies with environmental protection regulations such as RoHS and REACH.
High efficiency: The synergistic flame retardancy of phosphorus-nitrogen and phosphorus-silicon significantly enhances the flame retardant efficiency.
Processability: Good compatibility with various polymers, suitable for extrusion, injection molding and other processes.
——————————————————————————–
Seventh, future development direction
Nanoscale technology: Developing nanoscale flame retardants to enhance dispersion and flame retardant efficiency.
Bio-based flame retardants: Flame retardants are prepared using renewable resources to reduce reliance on fossil resources.
Multi-functionalization: Flame retardants have functions such as toughening, antibacterial, and anti-aging, enhancing the comprehensive performance of materials.
Green synthesis: Utilizing environmentally friendly processes to reduce pollutant emissions during the production process.
——————————————————————————–
Summary: Organic low smoke zero halogen flame retardants achieve a balance between efficient flame retardancy and environmental protection requirements through the synergistic effect of elements such as phosphorus, nitrogen, and silicon. In the future, with the development of nanotechnology and bio-based materials, their performance and application fields will be further expanded.
