VISUAL EXAMINATION OF METAL-LOOK FINISHES STABILITY AFTER ACCELERATED AGING TEST ON POLYMERIC COMPOSITES APPLIED IN THE PROFESSIONAL KITCHEN ENVIRONMENT

Introduction: In the professional appliance industry, materials selection for metal replacement represents an opportunity for the design of the components characterized by manual interaction with the user. It allows, indeed, to fulfill ergonomic design and safety requirements (e.g., electrical and thermal insulation). Although, as professional appliances are characterized by an intense use in harsh environments, the materials and finishes’ durability in time have to be studied. Materials and methods: Polymer samples, characterized by six different metal-look finishes, have been prepared by accelerated aging. The samples were exposed to temperature and the most present chemical solutions in the professional kitchen environment (5 food chemicals and 4 surface cleaners). The stainless steel-look finishes that were selected, were developed by bulk-technology, water transfer printing, painting, and aluminum and stainless steel PVD coating. Results: A visual evaluation of the finishes colour alteration was performed, both by spectrophotometric analysis (Konica Minolta CM-2600d) and stereomicroscopy (Leica model M165 C). One metal-look painting finishing (Z), already applied in the professional kitchen environment, was used as the reference sample. The analysis showed that the highest values in ΔE (colour variation) was registered in the case of PA composite coated by water transfer printing (C) (38.978) and by aluminium PVD (S) (30.938), both immersed in vinegar solution. Chlorine monofluoride demonstrated to be the most aggressive surface detergent solution regarding both C sample (34.707) and S sample (34.960). The same solution sensibly interacted also with the ABS painted sample (R) (21.876). Discussion: On the basis of the data collected by the experimental tests, we can conclude that some finishes exhibit an evident chemical incompatibility with the chemical solutions present in a professional kitchen environment. PVD coated Aluminium and water transfer printed PA composite samples have been significantly degraded by both surface cleaners and food chemicals, in particular by vinegar and chlorine monofluoride. Moreover, some colour alterations were detected also on painted samples, when tested with some detergents. Further studies at different aging conditions (time, temperature, chemical solution) should be conducted to examine the degradation of composites materials and finishes in such environment.