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Isocyanates
MDI (Methylene Diphenyl Diisocyanate) Supplier
MDI is the isocyanate behind rigid insulation, sandwich panels and a wide range of moulded foam, adhesives and elastomers. Ambizent supplies pure and polymeric MDI to manufacturers worldwide, with a Certificate of Analysis on every shipment.
From refrigerator insulation to sandwich panels to industrial adhesives, MDI is the isocyanate behind an enormous range of rigid and specialty polyurethane products. Ambizent supplies both pure MDI and polymeric MDI (PMDI) to manufacturers worldwide, matched to the polyol system and process each application needs.
MDI is a family, not one product
Pure (monomeric) MDI — 4,4'-diphenylmethane diisocyanate, CAS 101-68-8 — is the two-ring molecule with a functionality of two, used in elastomers, CASE applications and some flexible or prepolymer systems. It is a white to pale-yellow solid at room temperature (melting point roughly 39–43 °C).
Polymeric MDI (PMDI), commonly registered under CAS 9016-87-9, is what most rigid-foam producers actually use: a mixture of monomeric MDI (typically 40–50%) together with minor 2,4'- and 2,2'-isomers and a distribution of higher-ring oligomers making up the remainder. That higher-than-two average functionality is what builds the tightly crosslinked, dimensionally stable network rigid insulation needs — and unlike the solid monomer, PMDI is a dark reddish-brown liquid at room temperature, straightforward to process on rigid-foam lines.
Values are typical and for guidance only; exact grade specification is confirmed on the batch Certificate of Analysis provided with every shipment. Always consult the current Safety Data Sheet before handling.
Why source MDI from Ambizent
Certificate of Analysis on every shipment — verify NCO content and functionality before use.
Worldwide supply from our UAE hub — the Middle East, Africa, South Asia and beyond.
Matched systems — source MDI alongside rigid polyols, catalysts and flame retardants from one partner.
Origin flexibility — MDI is a concentrated, outage-prone market; we source across producers to keep you supplied.
Pure (monomeric) MDI — 4,4'-diphenylmethane diisocyanate, CAS 101-68-8 — is a two-ring molecule with functionality of two, used in elastomers, CASE and some flexible/prepolymer systems. Polymeric MDI (PMDI), commonly registered under CAS 9016-87-9, is a mixture of MDI plus a distribution of higher-ring oligomers, giving an average functionality above two — the reason PMDI dominates rigid foam, which needs a highly crosslinked network.
Why is MDI used for rigid foam instead of TDI?
Rigid foam needs high crosslink density for dimensional stability and thermal performance, which PMDI's above-two functionality delivers and difunctional TDI cannot. MDI also has much lower vapour pressure than TDI, making it markedly safer to handle, and its chemistry suits the high-index polyisocyanurate (PIR) systems used in fire-rated insulation.
Is MDI a solid or a liquid?
Pure 4,4'-MDI is a white to pale-yellow solid at room temperature, with a melting point around 39-43 degC — it must be melted or handled as a prepolymer/solution for many uses. Polymeric MDI (PMDI), by contrast, is a dark reddish-brown liquid at room temperature, which is why PMDI rather than pure MDI is what most rigid-foam producers actually process.
What NCO content and functionality should PMDI have?
Commercial PMDI for rigid foam typically runs around 30-31% NCO by weight, with an average functionality commonly in the 2.7-2.9 range and a viscosity in the low hundreds of mPa.s. The exact grade should be matched to your polyol system and process — tell us your application and we can advise.
How should MDI be stored?
MDI reacts with atmospheric moisture, so it must be kept sealed and dry, ideally under a dry-nitrogen blanket, within the temperature range the data sheet specifies — too cold and it can crystallise or haze, too hot and shelf life shortens. Rotate stock so material is used within its shelf life and check for haze or sediment before use.
Let's Work Together
Need MDI or Polymeric MDI (PMDI)?
Tell us your process — rigid board, appliance, spray foam or moulded flexible — and destination port, and we'll match a grade and quote it alongside your polyol system.