Both TCPP and TEP are liquid phosphate ester flame retardants used in polyurethane foam and rigid PU systems. They share a similar physical form but serve different formulation requirements: TCPP is halogenated and delivers higher FR efficiency; TEP is halogen-free and appropriate where chlorine-containing additives are restricted or undesirable.
TCPP: Properties and Applications
TCPP (tris(1-chloro-2-propyl) phosphate, CAS 13674-84-5) is the most widely used liquid flame retardant for polyurethane foam. It functions via a gas-phase mechanism through chlorine radical scavenging during combustion. TCPP integrates into the PU foam matrix during the reaction, providing durable fire resistance without migration.
Primary applications: flexible PU slabstock foam (furniture, bedding), rigid PU insulation, CASE adhesives and sealants, spray polyurethane foam (SPF). Typical loading: 5–15 phr depending on target standard (UL 94 HF-1, Cal TB 117, ASTM E84).
Note: TCPP is not listed under California Proposition 65 (TDCPP is; the two are often confused). Consumer product manufacturers should independently assess labeling obligations. Consult qualified legal counsel. See our Prop 65 analysis for further detail.
TEP: Properties and Applications
TEP (triethyl phosphate, CAS 78-40-0) is a halogen-free FR and reactive diluent for rigid polyurethane, epoxy laminates, and coatings. As a reactive component in PU systems, TEP integrates into the polymer network during cure, providing permanent fire resistance without migration.
TEP has lower FR efficiency per unit loading compared to TCPP, which means higher loadings are typically required to achieve equivalent fire performance. This is offset by the halogen-free profile, which eliminates Prop 65 exposure risk and supports formulations requiring halogen-free certification. Also functions as a reactive diluent to reduce viscosity in isocyanate blends during processing.
Comparison Table
| Property | TCPP | TEP |
|---|---|---|
| FR mechanism | Gas-phase, chlorine radical scavenging | Gas-phase + reactive (phosphorus) |
| Halogen content | ~32 wt% chlorine | None |
| Prop 65 exposure | Listed (consumer product assessment required) | Not listed |
| Typical loading (phr) | 5–15 | 10–25 |
| Primary applications | Flexible foam, rigid PU, CASE, SPF | Rigid PU, epoxy, coatings requiring HF |
| Viscosity (25°C / 77°F) | 65–90 cP | <3 cP (very low) |
| TSCA status | Listed | Listed |
Which to Choose
Use TCPP when:
- Maximum FR efficiency at lower loading is required
- Application is flexible foam (furniture, automotive seating, bedding)
- No Prop 65 consumer product concern applies
- Cost-efficiency is a priority
Use TEP when:
- Halogen-free certification is required
- Application is rigid PU insulation or epoxy laminate
- Prop 65 labeling exposure is a concern for consumer products
- Viscosity reduction in processing is a secondary benefit
Both TCPP and TEP available with DDP pricing. Request pricing and TDS.
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