Time filter

Source Type

Mirschel G.,Leibniz Institute of Surface Modification | Daikos O.,Leibniz Institute of Surface Modification | Heymann K.,Leibniz Institute of Surface Modification | Decker U.,Leibniz Institute of Surface Modification | And 4 more authors.
Progress in Organic Coatings | Year: 2014

Near-infrared (NIR) reflection spectroscopy was used for in-line monitoring of the conversion in printed layers of a UV-curable cyan printing ink at an offset printing press. Quantitative analysis of the spectra was based on the calibration of the method with chemometric approaches using reference data for the conversion obtained by FTIR/ATR spectroscopy. In this way, the conversion in ink layers with a thickness of 0.8 g m-2 was determined with a precision of 5%. Moreover, it was shown that the specific migration of the acrylate components in the binder of the printing ink was linearly dependent on the conversion in the studied range between about 80% and 100%, which allowed an estimation of the specific migration from conversion data. The strict linear relation between both parameters was used for indirect in-line monitoring of the acrylate migration during the printing process by predicting it from the conversion data derived from the NIR spectra. For comparison, off-line measurements on random samples by HPLC were carried out. The error of the predicted migration data in comparison with the results of the analytic measurements was found to be about 0.03 mg dm-2. The proposed indirect prediction of the migration will allow a better and more direct control of technical printing processes. © 2014 Elsevier B.V.


Mirschel G.,Leibniz Institute of Surface Modification | Daikos O.,Leibniz Institute of Surface Modification | Heymann K.,Leibniz Institute of Surface Modification | Scherzer T.,Leibniz Institute of Surface Modification | And 3 more authors.
Progress in Organic Coatings | Year: 2014

In this study, it was demonstrated that the conversion in printed layers of UV-cured printing inks and varnishes can be determined in-line in a printing press by NIR reflection spectroscopy supported by chemometric methods. Layers were printed with a thickness of ∼1.2 g m-2 for a printing ink and ∼2.8 g m-2 for a printing varnish. Quantitative analysis of the spectral data was carried out with calibration models based on the partial least squares (PLS) algorithm. In-line monitoring tests were performed at a large-scale sheet-fed offset printing press in order to evaluate the predicting performance of the calibration models under process conditions. Different conversions in the layers were induced by variation of the irradiation dose. The predicting errors were 4.5% for the ink and 4.0% for the varnish. The printing speed was found to have no significant influence on the precision of the measurements. © 2014 Elsevier B.V. All rights reserved.


Daikos O.,Leibniz Institute of Surface Modification | Mirschel G.,Leibniz Institute of Surface Modification | Genest B.,Saxonian Institute for the Printing Industry SID | Scherzer T.,Leibniz Institute of Surface Modification
Industrial and Engineering Chemistry Research | Year: 2013

Near-infrared (NIR) reflection spectroscopy was used for in-line monitoring of the coating weight of printed layers of acrylate-based clear varnishes. Quantitative analysis of the spectral data was carried out by means of chemometric techniques based on partial least-squares (PLS) regression. The influence of variations of the chemical composition of the varnish formulations on the multivariate calibration models may lead to mispredictions of the coating weight. Therefore, it was compensated by special calibration procedures. Two different approaches were compared. Single-stage universal calibration included the different varnish formulations into one joint PLS model. Alternatively, the multistage procedure combined a preliminary identification step with subsequent quantitative analysis using specific calibration models for each varnish. The efficiency of both approaches was investigated by the prediction of the coating weights of independent test samples. Moreover, in-line measurements were carried out at a sheet-fed offset printing press. Both methods efficiently eliminated the influence of variations of the chemical composition. However, the multistage approach led to more precise predictions. In in-line monitoring trials during printing, the coating weight (in the range between 0.8 and 7 g m-2) was determined with a prediction error of 0.25 g m-2 with the single-stage calibration model and 0.17 g m-2 using the multistage approach. © 2013 American Chemical Society.


Mirschel G.,Leibniz Institute of Surface Modification | Savchuk O.,Leibniz Institute of Surface Modification | Scherzer T.,Leibniz Institute of Surface Modification | Genest B.,Saxonian Institute for the Printing Industry SID
Analytical and Bioanalytical Chemistry | Year: 2012

Near-infrared (NIR) reflection spectroscopy was used for monitoring the thickness or rather the coating weight of thin printed layers of transparent oil-based offset printing varnishes in a range from 0.5 to 5 gm?2. Quantitative analysis of the spectral data was carried out with partial least squares regression. Surface properties such as the gloss were found to strongly affect the prediction of the coating weight. This influence was minimized by the development of calibration models, which contained spectra of layers with a broad range of gloss levels. The prediction error of these models was in the order of 0.12 to 0.16 gm?2. In-line measurements were carried out at a sheet-fed offset printing press in order to test the performance of themodels under real process control conditions.Varnisheswere applied to paper at printing speeds of 90 or 180mmin?1. A close correlation between the predictions from in-line NIR spectra and the reference data from gravimetry was observed regardless of the specific degree of gloss of the layers (errors between 0.15 and 0.17 gm?2). The results clearly prove the efficiency of NIR reflection spectroscopy for quantitative investigations on thin layers in fast processes such as printing and demonstrate its analytical potential for quality and process control. © Springer-Verlag 2012.


Mirschel G.,Leibniz Institute of Surface Modification | Savchuk O.,Leibniz Institute of Surface Modification | Scherzer T.,Leibniz Institute of Surface Modification | Genest B.,Saxonian Institute for the Printing Industry SID
Progress in Organic Coatings | Year: 2013

Near-infrared (NIR) reflection spectroscopy assisted by chemometric methods was used for in-line monitoring of the coating weights of thin printed layers of clear varnishes applied to papers or polymer foils. The coating weights of the acrylate-based UV-curable layers were in the range between 1 and 7 g m -2. The precision of the multivariate calibration models was found to be strongly affected even by minor variations of the substrate which may lead to considerable mispredictions of the coating weight. The interfering effect of the substrate absorption was compensated by special calibration procedures. Two different approaches were used. Multistage calibration models combining an identification step with quantitative analysis allowed a clear assignment of any spectrum to specific calibration models. Alternatively, the variation of the substrate was included into the calibration model by use of a broader range of calibration samples. The efficiency of both approaches was demonstrated by the prediction of the coating weights of independent test samples. Moreover, in-line measurements were carried out at a sheet fed offset printing press. It was shown that the coating weights of printed layers can be determined with a prediction error of about 0.15 g m -2 for layers on paper or 0.3 g m -2 on PET foils. © 2012 Elsevier B.V.

Loading Saxonian Institute for the Printing Industry SID collaborators
Loading Saxonian Institute for the Printing Industry SID collaborators