A comparative study between experimentally measured mechanical attributes and users’ perception of soft feel coatings: Correlating human sense with surface characteristics of polyurethane based coatings

Different soft feel coating formulations using waterborne resins composed of soft and hard polyurethane resins were prepared. The effects of resins mixtures on the soft feel properties were studied. Attempts were made to find out the correlation between users perception and experimentally measured surface characteristics of the coatings. To this end, 72 people were asked to touch the coatings in a similar testing environment and to express their feeling in order to rank them between 1 (lowest soft feel effect) and 4 (highest soft feel effect). The coatings physical characteristics were studied by tensile test, micro Vickers hardness, atomic force microscope (AFM) and friction coefficient measurement. It was shown that the mixtures of 25:75 of soft and hard resins resulted in the best soft feel effect. Users did not consider low or high hardness films as soft. Instead, those coatings having greater toughness were ranked as the best soft feel effect. Also, coatings with lower friction coefficient and lower surface roughness were preferred by users. However, the lowest friction coefficient did not result in the best soft feel appeal. In fact, the mechanical properties, surface roughness and friction coefficient were found to play as the criteria to show soft feel effect. It is thus concluded that by selecting appropriate surface characteristics of coatings related to soft feel effect, good agreement between these properties and human feeling can be made.