Polybutylene terephthalate (PBT) is a

thermoplastic A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate ...

engineering polymer that is used as an insulator in the

electrical Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described ...

and

electronics The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...

industries. It is a

(semi-)crystalline

polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

, and a type of polyester. PBT resists solvents, shrinks very little during forming, is mechanically strong, is heat-resistant up to (or with

glass-fibre Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clot ...

reinforcement), and can be treated with

flame retardant The term flame retardants subsumes a diverse group of chemicals that are added to manufactured materials, such as plastics and textiles, and surface finishes and coatings. Flame retardants are activated by the presence of an ignition source and ...

s to make it noncombustible. It was developed by Britain's Imperial Chemical Industries (ICI). PBT is closely related to other thermoplastic polyesters. Compared to PET ( polyethylene terephthalate), PBT has slightly lower strength and rigidity, slightly better impact resistance, and a slightly lower glass transition temperature. PBT and PET are sensitive to hot water above (140 °F). PBT and PET need UV protection if used outdoors, and most grades of these polyesters are flammable, although additives can be used to improve both UV and flammability properties.

Applications

Polybutylene terephthalate is used for housings in electrical engineering, but also in automotive construction as plug connectors and in households for example in showerheads or irons. It is also found processed into toothbrush fibers and false eyelashes, and is used in the

keycap A keycap is a small cover of plastic, metal, or other material placed over the keyswitch of a computer keyboard. Keycaps are often illustrated to indicate the key function or alphanumeric Alphanumericals or alphanumeric characters are a co ...

s of some high-end computer keyboards because the texture is highly resistant to wear and discoloration due to UV radiation. PBT can also be made into yarn. This has a natural stretch similar to Lycra and can be incorporated into sportswear. Due to its chlorine resistance it is commonly found in swimwear. Further, recent studies have shown that PBT has superior UV properties to PET based fabrics such as T400. PBT, especially glass fibre grades, can be effectively fire-retarded with halogen-free products. Phosphorus-based flame retardant systems are used in these fire-safe polymers and are based on aluminium diethyl phosphinate and synergists. They are designed to meet

UL 94 UL 94, the Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances testing, is a plastics flammability standard released by Underwriters Laboratories of the United States. The standard determines the material� ...

flammability tests as well as Glow Wire Ignition Tests (GWIT), Glow Wire Flammability Test (GWFI) and

Comparative Tracking Index The Comparative Tracking Index (CTI) is used to measure the electrical breakdown (tracking) properties of an insulating material. Tracking is an electrical breakdown on the ''surface'' of an insulating material wherein an initial exposure to elec ...

(CTI). Main applications are in the electrical and electronics (E&E) industry.

Producers

* Anjacom (almaak international GmbH) * Arnite ( DSM) * Celanex (

Ticona Celanese Corporation, formerly known as Hoechst Celanese, is an American technology and specialty materials company headquartered in Irving, Texas. A Fortune 500 corporation, the company is the world’s leading producer of acetic acid, produc ...

) * Crastin ( DuPont) * Duranex PBT (Polyplastics) * Dylox (Hoffmann + Voss GmbH) * Kebater (BARLOG plastics GmbH) * Later (LATI) * Pocan (

Lanxess Lanxess AG is a German specialty chemicals company based in Cologne, Germany that was founded in 2004 via the spin-off of the chemicals division and parts of the polymers business from Bayer AG. Shares in Lanxess AG were listed in Germany’s DA ...

) * Precite (AKRO) * Rialox (RIA-Polymers GmbH) * Schuladur ( A. Schulman) * Ultradur (

BASF BASF SE () is a German multinational chemical company and the largest chemical producer in the world. Its headquarters is located in Ludwigshafen, Germany. The BASF Group comprises subsidiaries and joint ventures in more than 80 countries ...

) * Valox ( Sabic Innovative Plastics) * Vestodur ( Evonik Industries AG) * Badadur PBT (Bada AG) * Bergadur (PolyOne Th. Bergmann GmbH) * Longlite (Chang Chun Plastics Co Ltd)

References

{{Authority control Polyesters Plastics Thermoplastics Terephthalate esters