A quick question regarding the inorgonic fillers in plastics.
During the production of polypropylene (PP) edgebands via extrusion, I saw and witness that the PP edgebands filled with stearate coated calcium carbonate have serious problems in bonding lacquer, paint and primer on the surface. In other words, the lacquer, paint etc. don't bond with the edgeband and they come off easily.. Unlike this, when I use uncoated calcium carbonate, there is no problem in lacquer, paint and primer bonding. I have some theories regarding the reduced chemical reactivity due to the presence of stereate coating, but not so sure..
Does anyone have a detailed explanation (maybe reaction-based) for this situation??
Thank you very much in advance, I will be waiting for your opinions