Material Performance Dependence on Polyolefin Film Temperature in Processing

This thesis is focused on the examination of extrusion coating product performance, which is aspired to improve with resin choice and essential process parameters such as melt temperature and air gap distance. The performance is defined via two main testing methods, which are hot air sealing and pinhole measurements. Furthermore, infrared (IR) thermometry is applied to monitor the polymer film temperature during processing and contribute the conclusions of the laboratory measurement results. Theoretical part presents essential information about polymer material, extrusion coating process and parameters, product properties and fundamentals of IR thermometry. Firstly, the structure, properties and polymerization of polyethylene are discussed, followed by the principles of extrusion coating process. The knowledge of extrusion coating is reinforced with process parameters and their influence is considered via product properties. Finally, IR thermometry is examined including theoretical basis, equipment introduction and measurement method. Experimental part includes trial runs to produce product samples and laboratory measurements that focus on the quality control. Experiments concentrate on three main variables; melt temperature, air gap and resin choice, which are adjusted through the measurements. Hot air sealing and pinhole analyses are performed after each trial run in order to monitor the product quality and discover optimal process conditions for every material. The ultimate goal is to examine combination of melt temperature, air gap distance and material, which produces the best possible hot air sealing and pinhole results with the lowest possible coating weight. The measurements of experimental part offer a few confirmed outcomes, which enable conclusions concerning optimal melt temperature and air gap settings. Furthermore, comparison between different resin choices is possible. Higher melt temperature setting mainly improves hot air sealing and pinhole results. However, some resins does not endure excessive heating and degradation and the properties start to decline. The effect of air gap is similar to the melt temperature. Higher air gap setting decreases sealing temperature and reduces pinholes almost invariably despite increased cooling of the film. Moreover, increased neck-in must be noticed as the advantages of higher air gap are considered. The comparison of resin choice produce the most controversial results and the effect of blending is partially indefinite. First set of measurements support the blending in order to improve hot air sealing and pinhole results, but the advantage is disappeared in subsequent examination. Furthermore, increased material cost do not support the use of blends