Relationship Between the Surface Topology Observed by AFM And The Properties of Waterborne Polyurethane Coatings

摘要

Atomic force microscopy (AFM) was used to image the surface of the coatings made of waterborne polyurethanes and poly(acrylic urethane)s. Tapping-mode AFM observations were performed under the air and the water-soaked condition. Degree of dispersion particle coalescence was clearly observed by tapping-mode AFM. It was shown that the degree of coalescence depends on several factors such as raw materials, size of dispersion particle, temperature, and whether an assisting agent was used or not. It is known that the properties of the waterborne polyurethane coatings, such as physical strength, water-resistance and adhesiveness to base materials, were affected by the factors like described above. Through this investigation, the degree of coalescence is found to have a relationship to the surface properties. The well-coalesced coatings represented good physical properties and water-resistance. On the other hand, poor water-resistance that is swelling of coating was observed on the coatings having nano-ordered rough surface of which the unevenness corresponds to the residues of dispersion particles.