Phosphorus-based low smoke zero halogen flame retardants have significant flame retardant efficiency. Their core advantages and application characteristics are as follows:
First, highly efficient flame retardant mechanism
The dual effects of the gas phase and the condensed phase
Gas-phase flame retardancy: Phosphorus-based flame retardants such as red phosphorus decompose at high temperatures to form substances like phosphoric acid and polyphosphoric acid, which capture free radicals in the combustion chain reaction and interrupt the combustion process.
Condensed phase flame retardancy: Catalyzes the dehydration of polymers to form carbon, creating a dense carbon layer that isolates the transfer of oxygen and heat.
Low addition amount and high efficiency
Only 5%-10% of red phosphorus needs to be added to meet the UL 94 V-0 flame retardant standard, which is significantly lower than traditional flame retardants such as aluminium hydroxide and magnesium hydroxide (usually requiring an addition amount of 30%-50%).
Second, low smoke and halogen-free characteristics
Low smoke density
The smoke density (SDR) during combustion can be reduced by more than 60%, meeting the requirements of environmental protection regulations such as RoHS and REACH.
Halogen-free environmental protection
It contains no halogens and does not release toxic gases such as dioxins when burning. It is suitable for confined Spaces such as subways and high-rise buildings.
Third, typical application cases
The field of wires and cables
A certain brand of communication cable in Europe adopts microencapsulated red phosphorus (with an addition amount of 8%), the smoke density is ≤50 (ISO 5659-2), it has passed the bundle burning test of IEC 60332-3, and the tensile strength of the material is >12 MPa.
The field of electronic materials
Flame-retardant nylon (PA6/PA66) used for mobile phone casings and circuit board substrates, compounded with red phosphorus and nitrogen-based flame retardants, with the oxygen index (LOI) increased to 32%, and passed the 850 ° C hot wire test (IEC 60695-2-12).
The field of power batteries
The red phosphorus – expanded graphite system is added to the flame-retardant coating of the power battery pack to achieve rapid carbon formation, effectively delay the spread of thermal runaway, and meet the safety standard of GB/T 18384.3-2015.
Fourth, technological breakthroughs and improvements
Surface coating technology
The problems of hygroscopicity, oxidizability and coloring of red phosphorus were solved through microencapsulation technology (such as melamine-formaldehyde resin coating), with the humidity sensitivity reduced by 70% and the compatibility with the polymer matrix improved.
Synergistic flame retardant system
Red phosphorus is compounded with metal oxides (such as MgO, ZnO) to neutralize acidic gases, reducing the generation of PH₃ by more than 90% (tested in accordance with ISO 19702).
Nanocomposite material
Develop nano-red phosphorus composite materials. Utilize particle size control (50-100 nm) to enhance flame retardancy efficiency while avoiding the impact on the mechanical properties of the materials.
Phosphorus-based low smoke zero halogen flame retardants achieve excellent flame retardant performance at low addition amounts through an efficient dual flame retardant mechanism of gas phase and condensed phase, while meeting the environmental protection requirements of low smoke and zero halogen. They have significant advantages in fields such as wires and cables, electronic materials, and power batteries.
