In this article we explore the best adhesives and the approach to take for bonding PTFE.
What is PTFE?
PTFE (Polytetrafluoroethylene), traditionally known as Teflon®, is a naturally non-stick industrial coating used in high temperature and harsh chemical environments. As a result of this, bonding PTFE can be an extremely difficult process to achieve in industry without expert knowledge.
PTFE’s natural “non-stickiness” comes from its very low surface energy. It is a very high-density material which is excellent in its flexural and dielectric strength, as well as its electrical and water resistance.
Due to its unique properties, PTFE has applications in challenging environments including that of electrical components, pipework, windshield wiper blades, and cookware.
Main PTFE properties
Surface energy: 19mJ/m²
Maximum service temperature: 260°C
Melting temperature: 330°C
Surface preparation tips for bonding PTFE
It’s important to note that only chemically etched (“pickled”) or mechanically abraded PTFE is viable for adhesive bonding. Etching is traditionally done using fluorocarbon etchants. This process makes the surface much more available for bonding using epoxy resin adhesives such as Araldite.
The Teflon surfaces must be degreased before etching or abrading to remove all traces of dirt and oil. Additionally, abraded surfaces need to receive another degreasing treatment before an attempt at bonding. We suggest using an IPA wet wipe, or alternatively, alcohol, acetone or iso-propanol for the general degreasing process.
For further information on surface treatment, read: Surface Preparation for Adhesive Bonding
Best adhesives for bonding PTFE
Araldite 2014-2 offers durable bonds, room temperature curing, and great temperature and chemical resistance. This is ideal for use in electrical components due its minimal gassing and is also suitable in vertical applications as it is non-sagging up to 5mm. It can be applied manually or robotically to bond PTFE.
Araldite 2015-1 gives resilient bonds ideal for dissimilar substrates. It also offers room temperature curing and high shear and peel strength. Due to being non-sagging up to 10mm, and having good weathering resistance and thick viscosity, it is also suitable in vertical applications. This can also be applied manually or robotically.