Views: 277 Author: Vickey Publish Time: 2023-04-23 Origin: Site
Toluene diisocyanate (TDI) is an organic compound with the formula CH3C6H3(NCO)2. Toluene diisocyanate is also known as toluene diisocyanate, 2,4-toluphenyl diisocyanate (toluene-2,4-diisocyanate), diphenyl, 2,4-diisocyanate, and 4-methyl-1,3-benzenyl diisocyanate. Two of the six possible isomers are commercially important: 2,4-TDI (CAS: 584-84-9) and 2,6-TDI (CAS: 91-08-7).
Tolene diisocyanate is a transparent liquid with a colorless or pale yellow irritating odor that turns yellow under ultraviolet light. It is heated for easy polymerization in an alloy steel container and can react with hydroxyl compounds, water, amines, and compounds with active hydrogen to form carbamate, urea, carbourea, and urea. It can be miscible with ethanol (decomposition), ether, acetone, carbon tetrachloride, benzene, chlorobenzene, kerosene, olive oil, and diethylene glycol methyl ether, is toxic, and has the possibility of cancer.
Toluene diisocyanate can be used in a 500 ML grain glass bottle, an iron lid pressure glass bottle, a plastic bottle, or a metal bucket (tank) outside the ordinary wooden box packaging, filled with argon or nitrogen, and other sealed cool, dry, and light preservation. It is mainly used for organic synthesis, the production of foam plastics, paint, and as chemical reagents.
Toluene diisocyanate in open flame, high-heat combustible, and oxidant can react. With amines, alcohol, alkali, and warm water, the reaction is violent and can cause combustion or explosion. Heating or combustion can decompose them to generate toxic gas. Its steam is heavier than air, can spread quite far at lower places, and can reignite in the case of a fire. In the case of high heat, the pressure in the container increases, and there is a risk of cracking and explosion.
TDI mainly exists in the paint in the decoration; beyond the standard free TDI, it will cause harm to the human body, mainly sensitization and stimulating effects, eye pain, tears, conjunctival congestion, cough, chest tightness, shortness of breath, asthma, red papules, maculopapules, contact allergy, and other symptoms. The international standard for free TDI is below 0.5%.
The LD50 for TDI is 5800 mg/kg for oral contact and a LC50 of 610 mg/m3 for the vapor. Despite the low toxicity indicated, TDI is classified as "very toxic" by the European Community.
In the United States, the Occupational Safety and Health Administration has set a permissible exposure limit with a ceiling of 0.02 ppm (0.14 mg/m3), while the National Institute for Occupational Safety and Health has not established a recommended exposure limit due to the classification of toluene diisocyanate as a possible occupational carcinogen.
High concentrations of TDI vapor can stimulate the eyes and then seriously stimulate the nose and throat, which may produce chest tightness, which can cause asthma and even bronchospasm. Liquid TDI can also produce serious stimulation to the skin and eyes, and low toxicity can stimulate the stomach. So if someone accidentally touches or swallows TDI, we can take the following first-aid measures:
For skin polluters, they should immediately wash with soap and water, rinse their eyes with contaminated water for at least 15 minutes, remove contact lenses, and then seek medical treatment. For patients with TDI, symptoms usually appear several hours after feeding; do not vomit, let patients rest, and seek medical treatment. At present, there is no specific antidote for TDI poisoning, which is generally treated as preliminary stimulation or bronchospasm. If necessary, artificial respiration should be done in time.
