Validation of Direct-Read, Colorimetric Aromatic Isocyanate Detection System

摘要

Aromatic diisocyanates, such as toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI), are commonly used to make various polymers, such as polyurethanes. Polyurethanes have significant application in the manufacture of rigid and flexible foams. They are also used in the production of adhesives, elastomers and coatings. Polyurethane coatings are preferred in the automotive refinishing industry where high performance coatings are required. According to available toxicity data, in animals and epidemiologic studies of humans, aromatic diisocyanates such as TDI and MDI are strong respiratory sensitizers. Repeated exposures or a single large dose may cause sensitization. Validation of an aromatic isocyanates badge which may be used for personnel or area monitoring for exposure times ranging from 15 minutes to 24 hours under a wide variety of environmental conditions (11-90 % RH, 60-90℉, 10-100 cm/sec face velocity) is presented. The minimum detection limit over an 8 hour period for TDI is 0.6 ppb and for MDI is 0.4 ppb; however the badge may be used for personal or area monitoring from 15 minutes to 24 hours. A color comparator for higher resolution of TDI exposure dose was developed. The color comparator, when used in conjunction with the TDI badge, provides dose information for TDI exposures of 5, 7, 10, 15, 20, 30, 40, 60, 90 and 140 ppb-hr. Operational guidelines for the use of the color comparator are presented. The aromatic isocyanates badge is designed to monitor TDI and/or MDI vapors in the air, not aerosols or particulates.