Direct additive manufacturing of thermoplastic components on glazed surfaces by material extrusion using an adhesion promoter could open up new design and repair opportunities for white goods in kitchens and bathrooms, for ceramic screen-printing in the automotive industry or for enamel surfaces in the chemical industry. It also combines the different material properties of ductile thermoplastics with the hardness of glazed surfaces. Environmental conditions affect both the thermoplastic component and the adhesion-promoting aminosilane coating, e.g. through absorbed humidity, which causes generally reduced adhesion. Kitchen or bathroom items that can be suspended from the generatively manufactured elements, for example, also lead to a static load on the joint, which reduces the lifetime of the joint between the plastic and the glazed surface.

The research presented focuses on the reduction of critical static loads under defined climatic conditions and the aging process in the interface between an extruded thermoplastic polyurethane (TPU) head tensile specimen and an enamel surface created using (3-aminopropyl)trimethoxysilane (APTMS) as an adhesion promoter.

The compounds were characterized by using a constant load test comparing acetone cleaning and additionally applied amorphous silica coatings as different surface pretreatments for wet chemical APTMS coatings based on methanol, butanol and isopropanol, respectively. The aim of this approach is to evaluate the surface pretreatment in the context of aging in humid climates and the influence of the alcohols used on the kinetics of the polycondensation reaction as well as their influence on subsequent aging.