Boyd Coatings is now able to coat Nitinol medical devices with un-modified PTFE (or other high‑temperature‑cured fluoropolymer coatings) without adversely affecting the properties of the underlying Nitinol material.
Typically, pure PTFE requires temperatures of 700° F to cure. Because Nitinol materials cannot tolerate temperatures beyond 500° F without suffering adverse reactions, PTFE was previously applied using hybrid forms where a resin binder was added and it was the binder that cured at lower temperatures. This lower temperature binder was used to hold the PTFE in a matrix to preserve the characteristics of the Nitinol material.
Unfortunately, PTFE hybrids produce higher coefficients of friction, thus diminishing one of the most important characteristics that makes PTFE coating desirable. For example, the “slippery,” non-stick qualities of PTFE on a Nitinol medical device can be very significant toward that device’s success.
“We’ve developed a new process that allows us to apply high-temperature-curing fluoropolymer coatings, such as PTFE, to Nitinol in their pure form,” explained Don Garcia, director, R&D of Boyd Coatings. “To our knowledge, Boyd Coatings is the only company with this capability. Hybrid forms of PTFE with resin binders are no longer needed to keep below the Nitinol transition temperature. Being able to use the pure form of PTFE on Nitinol is a major technical development for manufacturers of Nitinol devices.”
Earlier this year, Boyd Coatings announced the availability of PTFE in six standard colors, as well as customized colors for use on medical products. Prime examples of medical devices currently utilizing colored PTFE include guidewires, mandrels and hypotubes. According to Garcia, these PTFE colors are also able to be applied to Nitinol.