Resin and volatile content of melamine-impregnated paper assessed by near infrared spectroscopy, a simulation of the industrial process using a laboratory-scale gantry

Melamine-impregnated paper is an important component in the production of high pressure laminates and melamine faced boards. The two most vital quality control parameters assessed during the production of impregnated paper are resin content and volatile content. This work explored the creation of near-infrared (NIR) reflectance models to assess these parameters. A laboratory scale computer-controlled high-precision table gantry was also tested for two reasons: to create an NIR profile of an impregnated paper sample, and to calibrate NIR models by moving the probe using the gantry while taking a spectrum. The NIR profile obtained using the gantry reveals that distinct spots on the surface of the paper have different NIR spectra. The use of the gantry for model creation shows similar or improved performance when compared to taking triplicate spectra of a sample on discrete areas. The time taken for sample analysis also was lower with the use of the gantry because only one spectrum was needed, instead of three. The gantry also enables the creation of models to be used at an industrial scale, allowing an increased range of reference values while not depending on the industrial process. The method can be used to improve reflectance NIR models of samples with heterogeneous or rough surfaces.