Polymethylene polyphenylene isocyanate

Polymethylene polyphenylene isocyanate (CAS 9016-87-9), commercially known as Polymeric MDI, is a dark brown liquid isocyanate used as a reactive building block in polyurethane synthesis.

Where is Polymethylene polyphenylene isocyanate used?

• Construction and insulation: primary isocyanate component in rigid polyurethane and polyisocyanurate foam systems for panels, spray foam, and pipe insulation
• Automotive and industrial: structural reaction injection molded parts, seat foam, and under-hood components requiring dimensional stability
• Adhesives and sealants: strong substrate bonding across wood, metal, and composite materials, particularly in wood composite panels such as OSB and LVL
• Coatings: moisture-cure and two-component systems for flooring, protective coatings, and elastomeric membranes
• It functions as a crosslinker and chain extender, reacting with polyols to form rigid or semi-rigid polymer networks.
• Serves as a binder in engineered wood products, including oriented strand board, particleboard, medium-density fiberboard, plywood, and laminated wood.
• Used as an insulation material in household appliances such as refrigerators, freezers, water heaters, and refrigerated display units.

Good to know: Technical grade is the predominant market form; food-contact or pharmaceutical grades are not applicable, as the product is intended for industrial use.

Formulation notes

• Compatible with polyester polyols, polyether polyols, catalysts, blowing agents, and other polyurethane additives.
• Solvent and additive compatibility is verified before scale-up.

Typical specification

• Isocyanate content is typically 30.20–32.00% by weight.
• Viscosity at 25 °C is typically 150–250 cPs.
• Functionality is approximately 2.6–2.7.
• Acidity expressed as HCl is ≤0.05%.

Regulatory status

• Included in the European Union Risk Assessment Report on methylenediphenyl diisocyanate (MDI).
• Has ACGIH TLV and BEI documentation.

Storage, packaging and handling

• Moisture exposure is controlled during formulation and storage.

Frequently asked questions about Polymethylene polyphenylene isocyanate

What NCO content and viscosity are typical for commercially supplied material?

Material is supplied with 30.2–32% NCO and a viscosity of 150–250 cps at 25 °C.

Which solvents can be used to dissolve the product?

It is soluble in acetone, THF, and toluene.

How does its vapor pressure affect industrial processing?

Its relatively low vapor pressure helps reduce evaporation during industrial processing compared to pure monomeric isocyanates.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.