TEP Flame Retardant Plasticizer in Rigid PIR Foam

TEP Flame Retardant Plasticizer in Rigid PIR Foam

Can one additive both plasticize and raise flame retardancy in rigid PIR foam? A phosphorus-containing additive can do both, which is why TEP (CAS 78-40-0) is used in highly flame-retardant flexible and rigid polyurethane foams and other systems that need a flame-retardant component. Performance depends on dosage and system density, so a trial against the target flame-retardant rating and test standard is recommended.

Why phosphorus works in rigid foam

Rigid PIR foam is a closed-cell material with a low thermal conductivity, and its fire behaviour depends on the balance between the isocyanate index, the blowing agent and the additive package. Phosphorus-based additives act mainly in the gas phase: they interfere with the radical chain reactions in the flame, which reduces the heat released and helps the foam self-extinguish. Because triethyl phosphate is a liquid with a plasticizing effect of its own, it can be metered into the polyol component and disperses without introducing a solid filler.

Setting the dosage

Dosage is usually expressed as parts per hundred of polyol and is decided by the flame-retardant requirement, the foam density and the blowing agent system. Two effects have to be balanced: raising the additive level improves the fire behaviour direction, while an excessive level can soften the foam, change the cell structure and influence the thermal conductivity.

Testing against the applicable standard

Fire performance claims are made against a classification standard, not against a laboratory observation. Rigid foam is usually assessed by the classification method required in the destination market, and the test has to be run on panels produced under the intended process conditions. Additive suppliers can describe the direction the dosage move takes, but the classification result belongs to the finished system.

Frequently asked questions

Is TEP a flame retardant or a plasticizer? Both. It is a phosphorus flame retardant that also acts as a plasticizer, which is why it is used in systems requiring a flame-retardant component together with viscosity control.

Can TEP be used in flexible foam as well? It is described as suitable for highly flame-retardant flexible and rigid polyurethane foams, as well as adhesives and coatings. The dosage differs by system.

What determines the final dosage? The required flame-retardant classification, the foam density and the blowing agent system, confirmed by a trial on the intended formulation.

Does it affect the foam's thermal conductivity? The effect depends on the level and the cell structure; the conductivity of the finished foam should be measured rather than assumed.

Request a sample and a recommendation

Send us your polyol system and target flame-retardant rating and our team will supply TEP as a 1kg complimentary testing sample dispatched worldwide via DHL or FedEx, with the current technical data. Trial order MOQ is 1 MT, and bulk shipments are loaded as 23 MT flexitank containers from Ningbo or Shanghai.