Adhesion promotion for paints and primers
PEEK polymer is resistant both to high temperatures as well as many solvents and chemicals, so it is well suited for applications that require it to withstand tough environmental conditions. Fibre-reinforced PEEK composites are designed to combine these benefits with high strength and light weight, so they are used in many engineering applications; for example in the aerospace industry they are used for primary and secondary structures as well as interior aircraft components. The problem with PEEK arises when it needs to be made compatible with another material to fulfil its function, namely if it needs to be painted, coated or bonded with adhesive.
Whilst amorphous plastics are disordered and contain free polymer regions, in semi-crystalline materials like PEEK the polymer chains are packed together in ordered regions. This prevents the polymer chains from being able to entangle with those in the paint (or adhesive) and this, combined with the fact that PEEK has excellent solvent and chemical resistance, means that bonding to PEEK is poor unless some kind of surface preparation has been carried out.
The perils and pitfalls of other surface preparation techniques like sanding and plasma treatment have been discussed in previous articles, but the key message is that often these methods are either not practical or are just not effective enough to withstand the requirements of the product within its lifetime.
Onto™ adhesion promoters improve the bonding of coatings, paints and adhesives to PEEK and fibre-reinforced PEEK composites. An example of the efficacy of Onto™ can be seen in the photos below, in which PEEK coated with a 2K polyurethane primer is subjected to the cross-hatch tape test, a simple method for showing how well a coating is bonded to a substrate. In the sample with no surface preparation the primer is pulled off by the tape, but in the Onto™ treated sample it stays put. In fact, Onto™ enhances bonding even in harsh environmental conditions, making it a good choice of surface preparation technique for demanding applications.
Onto™ adhesion promoters are designed to be simple to use. We have a range of different products so we can solve a range of bonding challenges and integrate a solution into a variety of manufacturing environments.
So if we have “PEEKED” your curiosity (sorry…), please get in touch, we would love to help you solve your PEEK bonding challenges.