PTFE tubing: One product, many uses

 The evolution of Polytetrafluoroethylene (PTFE) - more commonly known as Teflon(r) - from a niche product used only in high-value applications to a mainstream requirement has been very gradual.

PTFE has become viable in more than 200 applications, both industrial and consumer, over the last two decades. While sheets, rods and coatings still dominate the market for PTFE products and are the most popular, PTFE tubing, and PTFEhose, is now the main growth area.

PTFE tubing

The use of PTFE tube is widespread across many industries, including automotive, chemical and electrical, as well as medical. Fig 1 illustrates the many uses of PTFE tubing. Table 1 lists the key properties.

• PTFE's ability to withstand temperatures exceeding 250oC in automotive applications makes it an ideal candidate of high temperature fluid transfer.
• PTFE tubing has a huge market because of its chemical inertness and lubricity. PTFE tubing is safe to insert into human bodies.
• Due to its inertness, durability and superior performance, PTFE can be used as a replacement for glass in chemical applications.
• The excellent dielectric properties that virgin PTFE has make it ideal for insulation high-voltage cables.

PTFE tubing for the medical device market

Medical applications generally use small diameter spaghetti tubes. PTFE's use in this field is based on two important properties: lubricity, and biocompatibility. Fluoropolymers have a very high level of lubricity, compared to other plastics. With a coefficient of friction (0.1), PTFE is the most slippery polymer. FEP, which has a coefficient of friction (0.2), is next. These two polymers make up the majority of fluoropolymer tubing used for medical devices.

It is a concern that any polymer used in medical devices may not be biocompatible. PTFE is a leader in this field and has a long track record of in vivo usage. The USP Class VI and ISO 10993 requirements for medical-grade fluoropolymers must be met. Processing cleanliness is an important aspect.

PTFE tubing-processing techniques

The complexity of PTFE polymer is what makes PTFE tubing unique. Most polymers can be molded easily using injection molding, which allows them to make complex shapes. However, PTFE is unable to be compressed moulded due to its high melting points and melt viscosity. Extrusion, as it is commonly used, cannot be used on PTFE due to its high melting point. PTFE paste extrusion is now a highly sought-after process, due to the increasing demand for PTFE tubing.

In the 1950s, PTFE extruded grades were used in wire and cable industries. The material's good dielectric properties proved crucial to the development of electronics markets. The extrusion of PTFE on a wire was the first step in making tubing. This labor-intensive process required a lot of time. Technology was developed in the 1960s that allowed PTFE to be extruded without the use of a wire core. This allows PTFE tubing can be economically manufactured in long continuous lengths.

Poly Fluoro plans to start manufacturing FEB Tubes, and FEP Hoses in the near future. FEP is part of the same PTFE family, but melt-processable means that the material can be drawn into much longer tubes with thinner walls. Poly Fluoro will once again be a pioneer in a new area for fluoroplastics manufacturing with its entry into FEP.