Zur Untersuchung der Bindenaht beim Spritzgießen duroplastischer Formmassen auf Epoxidharzbasis
Epoxy resins belong to the thermoset material group, which can be cured by e.g. heating, to obtain their stable form. Due to their excellent electrical insulation, high temperature and media resistance, epoxy resins are used widely in the electrical and electronics industry and are gaining more and more attention since the electrification of mobility. During injection of epoxy resin molding compounds, weld lines can be formed due to the given component geometry when two separate flow streams are joined together. The weld lines often lead to mechanical weaknesses and are recognized as a critical factor in the overall component. Since thermoset molding compounds obtain their dimensional stability in the injection molding process through curing reaction, the bond between the two flows at the weld line is also created by chemical reaction or covalent bonding. Depending on the process, molding compounds can be pre-cured differently before the weld line is formed. Whether the pre-crosslinking in the epoxy resin molding compound is responsible for the reduced weld line strength is not yet clear. In addition, injection moldable thermoset molding compounds are always highly filled with various fillers, making the flow behavior during mold filling strongly influenced by fillers. There is however a lack of research to understand how fillers in epoxy molding compounds affect the flow behavior during injection molding and subsequently influence the weld line strength. The aim of this thesis is to investigate the weld line strength of the injection molding of epoxy molding compounds regarding the curing behavior while mold filling, and the flow behavior caused by fillers. In doing so, selected process and material parameters in injection molding are varied and the resulting material and part properties are analyzed in detail. The aim of the thesis is to understand the fundamental mechanisms of reduced weld line strength in injection molding of epoxy resin molding compounds. Thus, countermeasures for optimizing the product quality can be derived in a target-oriented way by applying the material group.