Diisononyl Phthalate (DINP) — Frequently Asked Questions

DINP is a general-purpose plasticiser that makes PVC flexible. Its main uses are flooring, wall coverings, wire and cable, calendered film, synthetic leather, automotive plastisols, hoses and roofing membranes. It is chosen for its easy processing, low volatility and balanced cost. It is not used in toys and childcare articles that children can put in their mouths, where it is restricted.

DINP has longer, branched alkyl chains, which make it less volatile and more resistant to extraction, but slightly less efficient, so a little more is needed for the same hardness. It also has a different regulatory status: DEHP is subject to authorisation and wider restrictions under EU and UK REACH, while DINP's main restriction covers toys and childcare articles that can be mouthed.

Under EU REACH Annex XVII entry 52, and the equivalent UK REACH entry, DINP may not exceed 0.1% by weight in plasticised material in toys and childcare articles that can be placed in the mouth by children. Other uses are not restricted by that entry. Classification and Candidate List status have been under review, so check the current safety data sheet and lists before specifying it.

DINP is made from isononanol, a mixture of branched C9 alcohols, and the isomer distribution depends on how the alcohol is produced. The two CAS numbers, 28553-12-0 and 68515-48-0, describe DINP from different alcohol routes. Performance is broadly similar, but some approvals and documents name one CAS number, so confirm the one you need in the enquiry.

DINP is an ortho-phthalate with C9 alcohols; DOTP is a terephthalate with C8 alcohols. DOTP falls outside the ortho-phthalate restrictions and is often used where customers want to avoid them, while DINP offers similar or slightly better processing and lower volatility in many formulations. Switching usually needs small adjustments to plasticiser level and fusion conditions.