Discriminating Amino Resin Paints From Alkyd Resin Paints with Two Kinds of Pigments in Automotive Coatings in Forensic Analysis by FTIR Spectroscopy

摘要

The analysis of automotive coatings is important to forensic scientists, especially in the investigation of hit-and-run accidents. Amino resin paints, alkyd resin paints, and polyurethane paints are all popular automotive coatings. In this study, FTIR was employed to investigate these coatings, particular in amino resin paints. IR spectra were tentatively interpreted. The indicative peaks distinguishing amino resin paints (1550 cm ~(-1)) and alkyd resin paints (1600 cm ~(-1)/1580 cm ~(-1)) were summarized. Two kinds of alkyd resin paints (with the Pigment Scarlet Powder and with the Toluidine Red), which were frequently confronted in cases and might readily be read as amino resin paints in IR spectra, were studied and interpreted. The indicative peaks (1619 cm ~(-1), 776 cm ~(-1) and 1674 cm ~(-1), 1494 cm ~(-1)) were selected to discriminate these two kinds of alkyd resin paints from amino resin paints and avoid an incorrect certificate of authenticity. The data in this study can help the forensic scientists identify these three paints accurately, especially in the cases with the interference of the pigments.