Jowat Magazine 2015-09 EN

09 considerably when necessary. Even a few micrometres thick layer of a specifi- cally formulated primer can expand the surface of the substrate to be bonded considerably, leading to a significantly higher adhesive strength. The adhesi- ve is able to penetrate into the “cavities” of this three-dimensional microporo- us and rough structure (ill. 2), and the additional mechanical anchoring im- proves the bond strength and aging re- sistance of the compound even further. Other additives contained in a primer can etch or dissolve the surface of a substrate, so the primer can anchor firmly to the material and build up an extremely strong adhesion (ill. 1). Primers are a special field of competence Primer application is literally a science of its own. An extensive knowledge of adhesives (water-based dispersions, reactive or non-reactive hot melt ad- hesives), printing inks and coatings (solvent- or waterbased) is essential when deciding what primer to use. The assembly itself and the ultimate exposure of the produced part are also aspects that need to be taken into ac- count. For an optimal primer applica- ill. 1: The primer links firmly to the surface of the substrate. ill. 2: Solvent primer on polypropylene (top view) – 5,000 times magnification.

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