In terms of coating solutions, there is no silver bullet and that is where our technical expertise forms a valuable part of the problem solving exercise.
Fluoropolymer coatings are available in several formats and it is critical that the coating system must be carefully selected to ensure the most effective solution.
Although the coating is not actually ‘pure’ these are coating systems where the exposed film is as pure as possible, so that the interaction between the coating and mating part or process is with a coating that has minimal additives such as pigments, surfactants or binder resins. In such cases, the full properties of the fluoropolymer can be exploited, for example, the low friction and inert properties of PTFE or the superb release characteristics of FEP. These types of system will always need a prepared substrate and a primer or basecoat to provide adhesion to the base material and enhance corrosion resistance.
This type of system is built up in layers of either two or three layers. The first layer being a primer or a basecoat, followed by a mid-coat and finally, the top-coat. Multi-layer systems normally contain more additives such as pigments and fillers and are quite often produced so that the finished film is aesthetically pleasing. This type of system will always need a prepared substrate.
Single layer systems are the most diverse range of coatings. These systems are blends of fluoropolymer, resin, pigments and other additives such as ceramic fillers to provide re-inforcement, corrosion inhibitors, MoS2 or graphite for bearing, dry lubrication and anti-galling applications. Coatings are also available that contain nickel to provide some electrical conductivity or where dissipation of static is needed.
As the description implies, single layer systems do not need primers or base coats although some have optional primers that can be applied to improve overall performance but generally, these types of coatings are designed to be used as standalone systems. The resin that is blended with the fluoropolymer provides substrate adhesion, hardness and excellent abrasion resistance. A range of resins are used in different coating systems which benefit specific applications. The resin systems used can be either thermosetting or thermoplastic.
Although substrate preparation is always recommended, some single layer systems can be applied to a surface that has not been grit blasted, which is sometimes important for very thin substrate material or where a plating operation has been applied to the part prior to coating.
Single layer systems are available containing PTFE, FEP or PFA as the functional fluoropolymer. There are also several types of resin system that are used in different formulations to suit varying applications and end uses. They are also available in a wide range of colours.
This type of coating has been specially formulated to be applied to flexible substrates such as rubber and elastomers and other temperature sensitive substrates such as plastics, carbon fibre and even glass.
The key properties of this type of coating are low friction, good abrasion resistance, exceptional flexibility, hydrophobic and capable of elongation of more than 200%. The coating can also protect the substrate against chemical attack and degradation as a result of UV exposure.
Typical applications are door and window seals in the automotive industry, dry lubrication and chemical resistance on rubber ‘o’ rings and seals and even plastic covers for signalling equipment on trains to prevent the build up of ice and snow.