What Are the Precautions for Handling Organic Isocyanates?

To ensure production safety and personal safety, the following points should be noted when handling organic isocyanates:

Reactivity Precautions: Isocyanates have a very high reactivity, so extreme caution must be exercised during handling. Since isocyanates easily react with compounds containing active hydrogen such as amines, alcohols, and water, it is essential to strictly avoid contact with these substances during operation and storage. Contact with moisture can cause isocyanates to degrade, forming insoluble urea compounds and releasing carbon dioxide, which can lead to container bulging (if the container is sealed with moisture inside) and increased viscosity. The actual NCO content in isocyanates will be reduced, affecting stoichiometric accuracy. Long-term exposure to moisture can cause isocyanates to coagulate and become unusable. Therefore, during storage, ensure that containers are strictly dry and sealed, and protected with dry nitrogen gas. After use, the containers should be tightly closed. All containers and reaction equipment must be kept dry.

Personal Protection: Exercise caution to prevent direct contact with skin and splashing into eyes. Wear necessary protective equipment (rubber gloves, goggles, work clothes, etc.). If isocyanates come into contact with skin or eyes, rinse immediately with clean water. Clean skin with soap and water. If isocyanates splash into the eyes, rinse with water for 15 minutes and seek medical examination. When skin contact occurs, it is recommended to first wipe with ethanol or ethanol-containing acetone solvent, then wash with soap. If not handled promptly, isocyanates can bind and harden with the skin, making it difficult to clean afterward.

Volatility and Toxicity: Due to the volatility and toxicity of isocyanates like TDI, which can irritate skin or mucous membranes (eyes and bronchi), it is necessary to wear protective masks or respirators when handling heated isocyanates that increase volatility. Even in cases of slight volatility, operators should take protective measures and be mindful of wind direction to avoid inhaling excessive isocyanate vapors. If exposure is brief, move to an area with fresh air immediately; if significant inhalation and poisoning occur, perform artificial respiration or provide oxygen, and seek emergency medical assistance.

Spill Management: In the event of isocyanate spills, immediately wipe up with waste cotton or paper. For spills on the floor, use a prepared liquid treatment agent composed of 50% ethanol, 45% water, and 5% concentrated ammonia, or wash with dilute ammonia water. Alternatively, cover with a solid treatment agent for 5-10 minutes before cleaning. Personal protection is also necessary during this process. Liquid and solid treatment agents can be pre-prepared and stored in sealed containers for immediate use. The formula for a solid treatment agent is as follows:

Sawdust: 23.0 parts

Clay (diatomaceous earth): 38.5 parts

Ethanol: 19.2 parts

Triethanolamine: 3.8 parts

Concentrated ammonia water: 3.8 parts

Water: 11.5 parts

Clothing Contamination: If isocyanates come into contact with clothing, they will adhere to fibers and harden. Use the aforementioned ethanol-containing treatment agent for cleaning, followed by rinsing with water.

Workshop Safety Measures

Install ventilation equipment in the workshop to promptly expel isocyanate-contaminated exhaust gases. The expelled exhaust must be treated to remove toxic components to avoid severe environmental pollution around the workshop. Treatment methods include incineration, water treatment, activated carbon adsorption, heavy oil absorption and incineration, and steam treatment.

Disposal of Waste Isocyanates

There are three methods available for the disposal of waste isocyanates:

React with an excess of waste polyether or other active polymers to foam, then incinerate or bury.

Stir with an excess of 8% ammonia solution in an open container, react for 48 hours, then bury.

Dispose of in the same manner as other toxic chemicals, typically by incineration.