Tramaco GmbH has launched a new conductive functional coating, the DJIC-AS01. The water- and IPA-based system is based on a water-dispersible polyester-polyurethane and the conductive polymer complex PEDOT:PSS. It is intended for components and films where electrostatic charge must be reduced and dissipated in a controlled manner without significantly altering the visual appearance.
The coating is intended for applications in the ESD-dissipative sector. Tramaco lists application areas including electronic packaging, technical films, protective covers, machine covers, viewing windows, and other transparent plastic parts. Thin conductive layers on glass and transparent protective surfaces are also among the intended applications.
Conductivity via the coating film
The electrical function is provided by a network of PEDOT:PSS in the dried coating film. The polyurethane matrix provides film formation, adhesion, and flexibility. According to the available sample data, the surface resistance decreases as the dry film thickness increases. The values reported are approximately 10^7 ohms per square at 13.7 µm, about 10^6.3 ohms per square at 22.8 µm, and approximately 10^5.8 ohms per square at 32.0 µm dry film thickness.
This allows the achievable surface resistance to be tailored to the specific application by adjusting the application method, dilution, drying, and the resulting film thickness. Thinner films can provide greater transparency, while thicker films result in lower resistance values.
Substrates and Coating Architecture
Possible substrates include PET, PVC, glass, and pretreated polyolefins such as PE and PP. Depending on the substrate and performance requirements, a multi-layer system may be appropriate. This can consist of a pretreatment or adhesion primer, the DJIC-AS01 functional layer, and, if necessary, a very thin protective layer.
For practical implementation, Tramaco recommends application-specific paint and coating tests on the intended substrate. In addition to surface resistance, the evaluation should focus in particular on transparency, adhesion, abrasion and scratch resistance, resistance to water and cleaning agents, as well as performance after aging and under varying humidity conditions. “For many applications, DJIC-AS01 is initially best suited as a separate functional layer.” Direct use as an additive in any paint system should only occur after testing for miscibility and the effects on the conductive network.
With DJIC-AS01, Tramaco is expanding its range of functional coating solutions for industrial applications. Samples and further technical information are available from the company.