Characterization of sizes on textiles by in-line NIR chemical imaging

In the last years, demands on high quality products increases dramatically, e.g. in textile industry. In order to produce high functional textiles a numerous of chemical agents have to be applied to the fabrics, in several wet chemical treatments, in the production process. One auxiliary agent is the size. Sizes are colorless, water soluble substances which improve the mechanically stiffness of threads during weaving process. Usually, sizes have to be wash out of the fabric before further processing since they may affect the following production steps. Up to now, offline process control methods e.g. extraction of the size are the state of the art of process control in textile industry. It is obvious, that the time consuming and punctual analytical methods are no more seasonable for an optimal process control. Thus, alternative process control methods were on demand. This paper presents a study of the potential of NIR hyperspectral imaging for in-line analysis in textile technology. Application weights and spatial distribution of sizes on polyester fabric are investigated by NIR hyperspectral imaging. In a preliminary study a calibration to the application weight of the size was prepared and a PLS model was established. This PLS model was applied for the quantitative monitoring of the colorless size across the fabrics. Additionally, contaminants on the textile were visualized by NIR chemical imaging. Thus, NIR hyperspectral imaging is presented as a fast, precise and powerful analytical method which also fulfills the requirements of textile industry.