Basic information

Main use

Diphenyl methane diisocyanate is widely used in polyurethane foam plastics, elastomers and coatings, in addition, also used in waterproof materials, sealing materials, pottery materials, etc. Polyurethane foam made of this product, used as warm (cold), building materials, vehicles, ships parts; Refined products can be made into car stop, buffer, synthetic leather, non-plastic polyurethane, polyurethane elastic fiber, non-plastic elastic fiber, plastic film, adhesive, etc.

Fold edit this section manufacturing method

Diphenyl methane 4, 4-diisocyanate is produced by the following three technologies:

(1) phosgene method: using aniline as raw material, it first condensates with formaldehyde to form 4, 4-diaminodiphenyl methane (MDA), which then reacts with phosgene to form diphenyl methane 4, 4-diisocyanate;

(2) Aniline oxidation carbonylation method: Aniline reacts with carbon monoxide in the presence of oxygen to form aniline-methyl formate (MPC), which in the presence of acid catalyst condense with formaldehyde to form intermediates methylene -(n-methyl formate aniline-methyl formate) aniline-methyl formate (PMDU) and methylene diphenyl carbamate (MDU). The unreacted MPC was further converted to MDU under the action of trifluoroacetic acid. Finally, the thermal or catalytic decomposition of MDU produces the product diphenyl methane 4, 4-diisocyanate.

(3) Aniline methoxycarbonylation: aniline is used as raw material to react with dimethyl carbonate to produce methyl benzoate (MPC), the latter is condensated with formaldehyde in the presence of acid catalyst to produce intermediates methylene -(n-methyl formate aniline) aniline methyl formate (PMDU) and methylene diphenyl carbamate (MDU). The unreacted MPC was further converted to MDU under the action of trifluoroacetic acid. Finally, the thermal or catalytic decomposition of MDU produces the product diphenyl methane 4, 4-diisocyanate.

Among the above three processes, the next two non-phosgene processes are the direction of future development.

Industry chain 

Upstream raw materials: aniline, formaldehyde, chlorine gas, caustic soda, nitric acid, carbon monoxide.

Downstream products: polyurethane resin, polyurethane rigid foam, spandex, 

Toxicity and environmental effects

Diphenylmethane-4,4' -diisocyanate is a toxic chemical. Inhalation through the skin, accidental ingestion, contact with vapor, eyes, skin, mucous membranes, respiratory system, digestive system has a strong irritation or injury, inhalation of vapor can cause asthma. Severe irritation: rabbit cross eye 100mg, 24h; Rabbit Pair Skin 500mg for 24 hours; Mice inhaled LC50178mg/kg; Rat transoral LD502200mg/kg; Mouse transoral LD50 9200mg/kg. Diphenylmethane-4,4' -diisocyanate is sensitive to moisture, and can decompose carbon monoxide, nitrogen oxide, cyanide and other toxic gases in contact with water. Fire fighting and other operations need to pay close attention to prevent poisoning. Production process, especially phosgene method, raw materials, production process, emissions, waste, by-products should be strictly managed to prevent harm to the environment.

Folding edit this section packaging, storage and transportation

Diphenylmethane-4,4' -diisocyanate is packed in galvanized iron drum with nitrogen seal. Store in a cool, ventilated and dry storeroom, away from direct sunlight. The temperature of the warehouse should be below 15℃, and it is better to store it below 5℃. The products should be used as soon as possible. Keep away from fire and heat. Long-term storage, storage temperature should not exceed 20℃. Strictly waterproof, moisture-proof, in accordance with the provisions of toxic chemicals storage and transportation.

Forbidden compound：water and acid, alkali, alcohol, amine, copper, copper alloy.

Polymerization hazard：diphenylmethane-4,4' -diisocyanate at room temperature yellow color, easy to generate insoluble dimers, need to add stabilizer