27 April 2010 Detection of flexographic inks using NIR LCTF-based hyperspectral imaging
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Near-infrared (NIR) spectroscopy is a widely used method for material identification for laboratory and industrial applications. While standard spectrometers only allow measurements at one sampling point at a time, NIR Spectral Imaging techniques can measure, in real-time, both the size and shape of an object as well as identify the material the object is made of. The online classification and sorting of recovered paper with NIR Spectral Imaging (SI) is used with success in the paper recycling industry throughout Europe. Recently, the globalisation of the recycling material streams caused that water-based flexographic-printed newspapers mainly from UK and Italy appear also in central Europe. These flexo-printed newspapers are not sufficiently de-inkable with the standard de-inking process originally developed for offset-printed paper. This de-inking process removes the ink from recovered paper and is the fundamental processing step in paper recycling. Thus, flexo-printed newspapers are a growing problem for recycling as they reduce the quality of the produced paper if their amount exceeds a certain limit of the recovered paper. This paper describes the chemometric model development using an NIR LCTF based hyperspectral imaging system for the detection of flexographic printing inks. The achieved accuracy with the LCTF based system is above 95%. Subsequently the model was transferred to an industrial spectrograph based sorting prototype evaluating the application with an instrumentation that is suitable for the recycling industry. Again an accuracy of over 95% on the object level was achieved for a sorting test including the physical sorting of the objects using an array of pneumatic nozzles.
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Raimund Leitner, Raimund Leitner, Andreas Fritz, Andreas Fritz, Thomas Arnold, Thomas Arnold, Martin De Biasio, Martin De Biasio, } "Detection of flexographic inks using NIR LCTF-based hyperspectral imaging", Proc. SPIE 7680, Next-Generation Spectroscopic Technologies III, 76800F (27 April 2010); doi: 10.1117/12.852528; https://doi.org/10.1117/12.852528

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