Fluoropolymers are known for their combination of superior properties, whether chemical, electrical, or physical. Chances are that when you choose to use a fluoropolymer, it will have to be bonded with another part, whether metal, plastic, ceramic or composite, in order to perform its intended function. This can be a problem, since fluoropolymers are notorious for their lack of bondability. This lack of bondability is caused by the very stable, covalent carbon-fluorine bonds that make up your fluoropolymer. These bonds are so stable that the polymer has difficulty bonding to anything else, even temporarily. To improve bondability, one must remove some of these carbon-fluorine bonds. This process is called Fluoropolymer Etching, and is a solution that Fluortek, a Nordson Company, offers to combat the bondability problem.
Etching is a chemical process that removes the fluorine atoms from the surface layer of the fluoropolymer. This surface layer is so thin; it is most conveniently measured in Angstroms. Once the fluorine atoms are removed, the carbon atoms left behind in the etched polymer quickly forms temporary bonds with atoms from the air, such as oxygen, nitrogen, and sometimes even hydrogen. Since these bonds are much weaker, the carbon atoms are still reactive, reducing the surface lubricity and allowing for a more bondable product. Because of the loss of carbon-fluorine bonds, once the surface of your fluoropolymer is etched, the properties of the etched area are changed. One will no longer have the lubricous and low energy surface that is expected from a fluoropolymer. Instead, one will have a wettable, bondable, frictional surface upon which to glue, mold, or print onto your product.
While there are a variety of methods available for fluoropolymer etching, Fluortek exclusively uses a solution of Sodium Naphthalene for our in house etching processes. Fluortek offers alternate etching chemistries through subcontracts currently in place with outside etching companies.
Etching will only affect the chemistry of the surface with which it comes in contact. The properties of your fluoropolymer are kept intact not only underneath the etched surface, but on the entire remaining unetched surface as well, meaning that the etched product’s bulk properties are unaffected by this process.
The results of the etching are not permanent, however. If left unused for long periods of time or stored incorrectly, the etched part regains its initial low bondability.
Fluortek offers a variety of etching configurations:
- In-line surface (OD) etching during extrusion
- Dip-Etching; Offers more control such that only specific surface areas are etched
- Inside (ID) tube etching
- Aggressive etching; Fluortek subcontracts for alternate etch chemistries (please contact our engineering staff for additional information)
At Fluortek, Inc. all of our products are custom manufactured to meet our customers’ needs. Fluortek can assist whether you have a current design or require our engineering support to design an etching solution for your application.