Two-component, polyurethane paints containing aliphatic isocyanates are widely used in autobody spray painting. Such isocyanates can cause asthma, and skin exposure may be an important route of sensitization and may contribute to the development of isocyanate asthma. Autobody workers are frequently in contact with recently painted, dried auto parts. It is not known how fast the newly painted car swfaces are fully cured, that is, for how long unbound, isocyanate species remain on painted swfaces after initial drying. To address this question, scrap sections of auto bodies were painted and dried by autobody shop painters following regular practice. Routinely used paints were sprayed 23 different times on the parts. Drying was accomplished by baking the part in a paint spray booth by heating it with a heat lamp or air drying in the shop. The 23 sprayed swfaces were sampled at regular time intervals after drying to determine the presence of free NCO groups using the semiquantitative SWYPE technique. Quantitative isocyanate analysis was also performed on two sprayed parts using NIOSH method 5525. Geometric mean curing time of 23 painted surfaces was 56.4 hr (range: 0.8 hr to 32 days). Unbound isocyanate species of similar composition to the original bulk material remained present on the majority of sampled painted smfaces for up to 120 hours for typical paint formulations and for 1 month for others. The actual curing of polyurethane paints in autobody refinishing can be a slow process. Unbound isocyanates may remain on the surface of painted car parts for prolonged periods (days to weeks) after dried. Such surfaces are an under-recognized potential source of skin exposure to autobody workers.
Slow curing of aliphatic polyisocyanate paints in automotive refinishing: A potential source for skin exposure
Journal of Occupational and Environmental Hygiene ; 4 , 6 ; 406-411
2007
6 Seiten, 4 Bilder, 1 Tabelle, 26 Quellen
Article (Journal)
English
Amino resin curable water reducible epoxy systems for automotive refinishing paints
Tema Archive | 1997
|TIBKAT | 1984
|Aluminium pigments in vehicle finishing and refinishing paints
Tema Archive | 1991
|Engineering Index Backfile | 1938
Water-based coatings for automotive refinishing
Tema Archive | 1998
|