TRAMACO has introduced the new conductive functional coating DJIC-AS01. This water- and IPA-based coating system is based on a water-dispersible polyester-polyurethane and the conductive polymer complex PEDOT:PSS. It is intended for applications in which electrostatic charge must be reduced and dissipated in a controlled manner without significantly altering the optical properties of the component.
According to the company, the coating falls within the ESD-dissipative range. As such, DJIC-AS01 is aimed, among others, at manufacturers and processors of electronic packaging, technical films, protective covers, machine covers, and other components designed to protect sensitive electronic components from electrostatic discharge.
Conductivity via a PEDOT:PSS Network
The conductive effect is created by a network of PEDOT:PSS in the dried coating film. The polyurethane matrix provides film formation, adhesion, and flexibility. According to TRAMACO, electrical conductivity increases with increasing coating thickness. For sample data, the company cites surface resistances of approximately 10^7 ohms per square at 13.7 µm, approximately 10^6.3 ohms per square at 22.8 µm, and about 10^5.8 ohms per square at a dry film thickness of 32.0 µm.
The system is particularly relevant for thin, transparent functional coatings. According to the supplier, the achievable surface resistance can be tailored to the specific application by adjusting the application rate, dilution, drying, and the resulting dry film thickness. Generally, surface resistance decreases with increasing film thickness, while thinner films can provide higher transparency.
Possible Substrates and Applications
TRAMACO lists PET, PVC, glass, and pretreated polyolefins such as PE and PP as substrates, among others. Depending on the substrate and requirements, a multi-layer system may be advisable, such as one incorporating a pretreatment or adhesion primer, the DJIC-AS01 functional layer, and, if necessary, a thin protective layer.
The listed applications include ESD-protective packaging such as trays, blisters, films, and component containers, as well as transparent plastic parts, viewing windows, protective covers, machine covers, and technical film coatings. Thin conductive layers on glass and transparent protective surfaces are also cited as potential applications.
Application-Specific Testing Recommended
Before use, TRAMACO recommends conducting application-specific paint and coating tests on the intended substrate. In addition to surface resistance, these tests should evaluate transparency, adhesion, abrasion and scratch resistance, resistance to water and cleaning agents, as well as performance after aging and under varying humidity conditions. According to the company, direct use as an additive in other paint systems should only occur after testing for miscibility and the effects on the conductive network.