Leveraging the wide experience in automotive interior clear coating technologies, Cannon have developed a PU coating technique to improve the surface roughness of composites.

The process consists of injecting a special 2 component clear PU system over the cured composite part and to create a thin PU layer over the part that fills the roughness created by the fibre read-through effect. Due to the typically unbalanced mixing ratios of the clear PU systems, Cannon Afros has developed a dedicated three streams head to reduce the unbalance between the components and consequently improve the mixing quality. Additionally, to avoid the presence of air bubbles into the PU layer, the components are strongly degassed in to the machine tanks.

The surface coating is a promising technique to open the way to Class A and paintable cosmetic composites as chemical companies are making important steps ahead to develop Release Agents and PU clear chemicals that guarantee the coat adhesion to the part.