Polylactide for finishes with barrier effect

Flexible sheet materials such as artificial leather are mainly made from PVC or polyurethane. Their areas of application are broad. A lacquer finish on the material surface can significantly influence the requirements such as the mechanical robustness of artificial leather and the resistance to chemicals and soiling media. High-quality lacquers protect the surface from the penetration of a large number of chemicals, but so far, there has been no effective protection against staining by strongly coloured organic molecules (hair dye, Edding, ball pen etc.). Most solvents, disinfectants and creams also still present a challenge, as they are able to dissolve the lacquer layer or migrate into the lacquer layer.

Migration of organic molecules both into the polymer layer and out of the polymer layer through the lacquer layer presents a problem. The migration of plasticizers out of PVC leads to hardening of the PVC product and thus a change in properties (e.g. embrittlement). If the PVC coating is in direct contact with other materials such as laminated foams, the plasticizer migrates into these contact materials and changes their properties.

At FILK, lacquer with a good barrier effect for organic molecules based on polylactide (PLA) was developed. Depending on the composition of the PLA lacquer, it could be suitable for PVC or PUR artificial leather. The finish extremely retards the migration of plasticizers out of PVC synthetic leather or from colouring media into artificial leather. The PLA lacquer is solvent-based and has solids content of around 10%. Since it is a 1K system, it can be stored for a longer time. The application can take place in the usual gravure printing process with anilox rollers. The lacquer is dried at 150 °C for 3 minutes. This can be followed by embossing at temperatures of up to 155 °C.