Organic low smoke zero halogen flame retardants can be classified into the following main types based on their chemical structure and mechanism of action. Each type has unique performance characteristics and application scenarios:
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First, phosphorus-based flame retardants
Phosphate esters
Typical substances: Triphenyl phosphate (TPP), bisphenol A bis (diphenyl phosphate) (BDP)
Mechanism of action: Gas-phase flame retardancy (capturing free radicals) + solid-phase carbonization
Application: Engineering plastics such as PC, ABS, PC/ABS alloys, etc
2. Phosphonate esters
Typical substances: 9, 10-dihydro-9-oxa-10-phosphoafine-10-oxide (DOPO)
Features: High thermal stability, low volatility, and excellent hydrolysis resistance
Application: Epoxy resin, polyurethane, unsaturated polyester
3. Polymer phosphonate esters
Typical substance: Melamine polyphosphate (MPP)
Features: Good compatibility with the substrate, suitable for high-filling systems
Applications: Polyolefins, nylon, thermoplastic elastomers
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Second, nitrogen-based flame retardants
Melamine and its salts
Typical substances: Melamine cyanurate (MCA), melamine polyphosphate (MPP)
Mechanism of action: Gas-phase dilution (release of NH₃) + solid-phase carbonization
Application: Nylon materials such as PA, PBT, PET, etc
2. Dicyandiamides
Typical substance: Dicyandiamide (DCDA)
Features: Low cost, often compounded with phosphorus-based flame retardants
Applications: Rubber, coatings, adhesives
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Third, silicon-based flame retardants
1. Silicone resin
Typical substances: Polydimethylsiloxane (PDMS), silicone rubber
Mechanism of action: Physical barrier (forming a silicon carbide layer) + dilution effect (releasing H₂O)
Application: High-temperature flame-retardant materials, electronic packaging
2. Silicate nanomaterials
Typical substances: Montmorillonite, layered silicate
Feature: Nano intercalation technology enhances flame retardant efficiency
Application: Polyolefin, polyester, epoxy resin
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Fourth, intumescent Flame Retardant System (IFR)
1. Classic IFR system
Composition: Acid source (APP), carbon source (PER), gas source (MEL)
Mechanism of action: It expands upon heating to form a porous carbon layer, isolating oxygen and heat
Application: Polyolefin materials such as PP, PE, and EVA
2. New IFR system
Typical substances: Phosphoronitrile – triazine copolymer, phosphorus-containing siloxane
Features: It has both flame-retardant and toughening functions
Application: High impact resistance materials, composite materials
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Fifth, phosphorus-nitrogen co-flame retardants
Phosphoronitrile compounds
Typical substance: Hexachlorocyclotriphosphazonitrile derivative
Mechanism of action: P-N synergistically catalyzes carbon formation and releases inert gas
Application: High-temperature materials such as PC, PPO, PEEK, etc
2. Phosphamides
Typical substances: N,N’ -bis (diphenylphosphoacyl) hexamethylenediamine
Characteristics: Excellent thermal stability and hydrolysis resistance
Applications: Epoxy resin, polyurethane, polyimide
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Sixth, other special types
Bio-based flame retardants
Typical substances: phytic acid, chitosan, lignin
Features: Renewable, degradable, environmentally friendly
Application: Bio-based plastics, natural fiber composites
2. Nanocomposite flame retardants
Typical substances: Graphene/phosphorus-based flame retardant complex, carbon nanotube/nitrogen-based flame retardant complex
Feature: Nano effect significantly enhances flame retardant efficiency
Application: High-performance composite materials, conductive flame-retardant materials
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Seventh, Future development trends
Nanoscale and composite: The combination of nano-flame retardants and functional fillers (such as graphene, carbon nanotubes) enhances flame retardant performance and mechanical properties.
Bio-based and sustainability: Utilizing renewable resources to develop flame retardants and reduce reliance on fossil resources.
Multi-functional integration: Flame retardants have functions such as toughening, antibacterial, and anti-aging, meeting the comprehensive performance requirements of materials.
Green synthesis process: Solvent-free and low-temperature synthesis technology is adopted to reduce production energy consumption and pollution.
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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, bio-based materials and green chemistry, the performance and application fields of flame retardants will be further expanded.
