Reactive Phosphorus Flame Retardant for Epoxy (DOPO-Based)
CAS Number: 35948-25-5
Reactive Phosphorus Flame Retardant for Epoxy (DOPO-Based) is derived from DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) and chemically incorporates phosphorus into the epoxy cured network through reactive P–H or P–OH functionality, eliminating the migration and leaching that plagues additive flame retardants. At 3–5% phosphorus content in the cured system, it achieves LOI greater than 28% and UL94 V-0 rating at 1.6 mm, making it the leading halogen-free FR solution for PCB laminates, electronics encapsulants, and aerospace composite structures. Unlike brominated FR epoxies, DOPO-based systems produce minimal corrosive and toxic combustion gases.
Technical Specifications
| LOI | >28% |
| UL94Rating | V-0 at 1.6 mm |
| appearance | White to off-white solid or solution |
| phosphorusContent | 14–18% (in DOPO) |
| effectivePInCuredSystem | 3–5% |
Applications
- Halogen-free PCB laminates and copper-clad laminates (CCL)
- Electronics encapsulants and underfill materials
- Aerospace composite matrices requiring flame retardancy
- High-voltage electrical insulation castings
- Flame-retardant epoxy powder coatings for electrical enclosures
Key Features
- DOPO-Based Reactive Phosphorus Flame Retardant bonds chemically into the epoxy network — zero migration or leaching over service life
- Achieves UL94 V-0 and LOI >28% at low phosphorus loading (3–5%), minimising impact on mechanical and electrical properties
- Halogen-free — eliminates corrosive HBr/HCl combustion gases, meeting RoHS, REACH, and IPC-4101 halogen-free requirements
- Compatible with standard epoxy hardener systems including DDM, DDS, DICY, and anhydrides used in PCB and composite manufacture
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CAS Number
35948-25-5
Category
Epoxy System ChemicalsAvailability
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