Phosphate ester flame retardants have the characteristics of dual functions of flame retardant and plasticization. Alfa Chemistry provides you a range of phosphate ester flame retardants to help meet fire safety challenges.
Advantages And Disadvantages
Advantages
- Halogen free
- Improve flow processability in plastic molding
- Residue after combustion can be suppressed and re-ignition is prevented
- High flame retardant efficiency
- Less impact on photostability or light stabilizer action
- Less corrosive in processing and burning
- Little or no increase in the quality of the flame retardant material
Disadvantages
- Volatile
- Poor heat resistance
- Compatibility is not ideal
- May produce drips when burning
Flame Retardant Mechanism
When phosphorus flame retardant (PFR) burns, it generates phosphoric acid, metaphosphoric acid, polymetaphosphoric acid, etc., which are covered on the surface of the resin to promote the carbonization of the plastic surface to form a carbon film. The polymetaphosphoric acid is covered in a viscous liquid state on the surface of the plastic. The solid or liquid membrane prevents the escape of free radicals and keeps out oxygen.
In addition, PFRs are also a free radical scavenger. Using mass spectrometry technology, it was found that any phosphorus-containing compounds have PO· formed when the polymer is burned. It can combine with the hydrogen atoms in the flame area to suppress the flame.
Applications
Common phosphate esters, their features and applications, refer to the following table.
| Types | Features | Applications |
|---|
Tributyl Phosphate
(TBP) | Colorless liquid, phosphorus content 11.63%. | Suitable for PVC polyurethane foam, CA, CAB, etc. |
Triphenyl Phosphate
(TPP) | White needle-like crystal, phosphorus content 9.49%, freezing point 49.2 °C. | Suitable for cellulose, vinyl and rubber. |
Dimethyl Methyl Phosphate
(DMMP) | It is a colorless or light-yellow transparent liquid with low viscosity. Its phosphorus content is 25%, the decomposition temperature is higher than 180 °C, and it is miscible with water and various organic solvents. | As an additive flame retardant, it is widely used in polyurethane foam, unsaturated polyester and epoxy resin. |
Tricresyl Phosphate
(TCP) | Clear liquid with aromatic odor. | Mainly used for PVC, PE, conveyor belt, leather, wire and cable, flame retardant synthetic resin. |
| Tris(β-chloroethyl) Phosphate | Colorless to light yellow oily transparent liquid, chlorine content 37.2%, phosphorus content 10.8%, ignition point 285°C. Soluble in alcohol, ketone, ester, ether, toluene, benzene and other organic solvents, insoluble in fat, slightly soluble in water. | Its molecule contains two flame retardant elements, halogen and phosphorus, which have synergistic effect. Widely used in unsaturated polyester, polyurethane, acrylate, phenolic resin, cellulose acetate, etc. |
Research Information
Functionalized Phosphate Ester
Long Yan et al. synthesized a series of functionalized phosphate ester flame retardants (GPPBs) combined with graphene oxide (GO) and used them to produce transparent flame retardant coatings. In this work, GPPBs endow the coatings with excellent flame retardancy and smoke suppression properties by forming high-quality expanded carbons with excellent densification, oxidation resistance, and fire barrier effects. [1]
Transparent flame retardant coatings with GPPBs [1]
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Reference
- Long Yan, et al. (2020). "Synthesis of organophosphate-functionalized graphene oxide for enhancing the flame retardancy and smoke suppression properties of transparent fire-retardant coatings," Polymer Degradation and Stability 172, 109064.
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