Handling Isocyanates and Manufacture of Polyurethane Products

In the course of their work, operators need not be exposed to isocyanate vapours by inhalation if adequate precautions are taken. The vapour pressure of the isocyanate, the temperature resulting from the exothermic reaction of the isocyanate with hydroxyl groups and the elevated processing temperature of the components which is frequently necessary, all affect the concentration of the vapour. 

Exposure to aerosols containing isocyanate is conceivable during spraying of reaction mixtures. Apart from this, contact with the skin can only result from improper handling, and oral ingestion should never happen. 

Protection from isocyanate vapours liberated during polyurethane manufacture is usually achieved by installing permanent exhaust ventilation units which either exhaust directly to the atmosphere or pass their exhaust fumes through scrubbers which extract the isocyanate vapour through a sodium carbonate spray tower before atmospheric exhaustion occurs. Continuous vertically positioned exhaust hoods are common where continuous conveyor lines are involved for localized extract situations, vertical down-draught or horizontal extract modes are much safer for operatives, being designed to remove all isocyanate vapour away from an operative s face and body. These latter situations apply particularly in the manufacture of cast-moulded and reaction-injection moulded products. 

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