Overview
Diphenylmethane diisocyanate ( CAS 101-68-8 ), commonly known as MDI, is a core isocyanate monomer used to produce polyurethane polymers across rigid, flexible, and elastomeric applications.
It reacts with polyols to build polymer chains, enabling manufacturers to engineer foam density, hardness, and durability to precise specifications for various industrial uses.
In building and construction, MDI is the primary reactant in rigid polyurethane and polyisocyanurate insulation panels, where it delivers high thermal resistance in thin cross-sections.
Automotive manufacturers rely on MDI-based systems for structural foam components, seating, headliners, and interior trim parts requiring consistent load-bearing performance and safety.
In adhesives and sealants, MDI functions as a crosslinker that bonds dissimilar substrates including wood, metal, and composites under demanding mechanical and environmental conditions.
Coatings and elastomer formulators use MDI to produce abrasion-resistant surfaces for industrial flooring, rollers, and protective linings that must withstand heavy daily wear.
MDI is supplied as a liquid in several commercially distinct forms: pure 4,4'-MDI, polymeric MDI (pMDI), and modified MDI variants including prepolymers and carbodiimide-modified grades.
Polymeric MDI is the dominant commercial form for foam applications, while pure MDI grades serve elastomer formulators requiring tighter isomer control for high-end manufacturing.
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Physical Properties
| Melting Point | 37 °C |
| Boiling Point | 196 °C @ Press: 5 Torr |
| Density | 1.197 g/cm³ @ Temp: 70 °C |
| Flash Point | 196 °C |
| Appearance | MDI is a white to light-yellow, odorless flakes. A liquid above 37C. |
| Color | White to Almost white |
| Form | neat |
| Water Solubility | decomposes |
| Vapor Pressure | 0.066 hPa (20 °C) |
| Refractive Index | 1.5906 (estimate) |
Safety & Handling
Danger GHS07 GHS08 GHS06 Hazard Statements H315 Causes skin irritation H317 May cause an allergic skin reaction H319 Causes serious eye irritation H320 Causes eye irritation H330 Fatal if inhaled H332 Harmful if inhaled H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled H335 May cause respiratory irritation H351 Suspected of causing cancer H370 Causes damage to organs H372 Causes damage to organs through prolonged or repeated exposure H373 May causes damage to organs through prolonged or repeated exposure Precautionary Statements P203 Obtain, consult and follow expert instructions for use. P233 Keep container tightly closed. P260 Do not breathe dust/fume/gas/mist/vapours/spray. P261 Avoid breathing dust/fume/gas/mist/vapours/spray. P264 Wash … thoroughly after handling. P270 Do not eat, drink or smoke when using this product. P271 Use only outdoors or in a well-ventilated area. P272 Contaminated work clothing should not be allowed out of the workplace. P280 Wear protective gloves/protective clothing/eye protection/face protection. P284 In case of inadequate ventilation wear respiratory protection. P316 Get emergency medical help immediately. P317 Get emergency medical help. P318 IF exposed or concerned, get medical advice. P319 Get medical advice/attention if you feel unwell. P320 Specific treatment is urgent (see … on this label). P321 Specific treatment (see … on this label). P403 Store in a well-ventilated place. P405 Store locked up. P501 Dispose of contents/container in accordance with local regulations. P264+P265 Wash … thoroughly after handling. P302+P352 IF ON SKIN: Wash with plenty of water. P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing. P308+P316 Get emergency medical help immediately. P332+P317 Get emergency medical help. P333+P317 Get emergency medical help. P337+P317 If eye irritation persists: Get medical advice/attention. Get emergency medical help. P342+P316 Get emergency medical help immediately. P362+P364 Take off contaminated clothing and wash it before reuse. P403+P233 Store in a well-ventilated place. Keep container tightly closed. P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
Trade & Regulatory
| HS Code | 29291090 |
| Storage Class | 11 - Combustible Solids |
| WGK (Germany) | 1 |
Other Names
Related Products
Chemical Properties
- CAS Number
- 101-68-8
- EC Number
- 202-966-0
- Mol. Weight
- 250.25
- HS Code
- 29291090
- Category
- Catalysts & Catalyst Precursors