Polybutylene Terephthalate (PBT)

The wide range of PBT product performance available in the marketplace is a tribute to the versatility of this material. Probably the most commercially significant of the thermoplastic polyester family of engineering resins, PBT was launched in 1969 with the introduction of Ticona’s Celanex® 3300, a 30% glass-reinforced product. Moldability, dimensional stability, environmental and temperature resistance, electrical properties, colorability and surface finish are all key characteristics that have contributed to the growth of PBT.

The base polybutylene terephthalate resin is made by reacting butanediol with dimethyl terephthalate or terephthalic acid, and this material is the foundation for grades reinforced with fiberglass, minerals such as mica or wollastonite, stainless steel fibers, or carbon fibers, or filled with glass beads, or other essentially non-orienting fillers. Other important additives include flame-retardant packages, UV stabilizers and impact modifiers.

Filled and reinforced PBT grades have excellent molding characteristics and will fill complex and/or thin-walled parts in relatively short cycles. Levels of regrind up to 25% can be tolerated in many cases.

While PBT compounds are the larger share of products made from this versatile resin, there are also important applications for the neat polymer, which comes in a variety of viscosities to meet processing and performance requirements. Special grades are available for extrusion applications ranging from monofilament to fiber-optic buffer tubes.