A multipurpose material that can be adapted to a wide variety of functions

DURANEX® PBT is characterized by its heat resistance and outstanding electrical properties. Its excellent compatibility with various kinds of reinforcement and additive agents means that it can be given many different properties according to specific customer needs. This also allows us to develop a diverse range of grades in our product lineup. This versatile product is utilized in a wide range of areas from wire harness connectors in automobiles to all kinds of electronic components, and also in more familiar everyday items, such as make-up brushes and paper laminate food packaging.

Key properties

PBT is a linear thermoplastic saturated polyester containing ester bonds in its main chain. PBT stands for polybutylene terephthalate. It is a polymer belonging to the same family as PET resin.

Structural Formula

PBT possesses a high melting point and high degree of crystallinity, while a low water absorption rate and thermal expansion coefficient give the resin superior dimensional stability. Electrical properties are also superior, and only small changes in electrical properties are exhibited as a result of moisture absorption. Dielectric breakdown voltage is also high.

Both crystalline and non-crystalline structures coexist in PBT. As a result, additives can be readily employed to improve properties and produce various functionalities. Its varied grades include flame resistant grades, fast molding cycle grades, and high impact strength grades. PBT is adopted in a wide variety of familiar products used in everyday life such as electrical components (connectors, micro-switches and condenser cases), office equipment like keyboards, telephones, automotive parts such as in-car electronics and electric vehicle charger guns, medical devices, construction materials, and precision equipment.

Raw ingredients and production method

As PBT is an ester polymer, it is polymerized from esters, themselves synthesized from acids and alcohols. With terephthalic acid used as the acid ingredient and 1, 4-butanediol as the alcohol ingredient, PBT polymer is made via polycondensation. This method is known as the esterification method.

Terephthalic acid is a solid that possesses sublimability and, because purification is difficult, a method also exists whereby terephthalic acid is esterified using methanol, with resulting dimethyl terephthalate and 1, 4-butanediol polycondensated to form the PBT polymer. This method is “ester interchange.” Regardless of which method is employed to manufacture the PBT polymer, the same properties and performance are exhibited if the molecular weight is the same.

While unreinforced PBT is used widely, in general, the addition of reinforcing material improves mechanical and thermal properties. By incorporating various reinforcing materials, many grades of the PBT polymer with various characteristics are made.

List of leading grades

Property Characteristic Grade
HB, standard Unfilled 2002
HB, standard GF15% reinforced 3105
HB, standard GF30% reinforced 3300
Low warpage, LD series GF30% reinforced, hydrolysis resistance 733LD
Hydrolysis resistant GF30% reinforced 330HR
Hydrolysis resistant,heat shock resistant GF30% reinforced 531HS
Alkali resistance improved GF30% reinforced, hydrolysis resistance 532AR
Super high flow, HB GF30% reinforced SF3300
Super high flow, HB GF30% reinforced, low warpage SF733LD
Flame retardant, excellent glow-wire property GF reinforced 330GW*
Higher impact resistant Unfilled, flame retardant, higher comparative tracking index 457EV
Halogen-free, higher comparative tracking index GF30% reinforced 330NF
Better surface appearance, higher gloss, flame retardant GF reinforced,low warpage 756HA
Flame retardant,standard,UL approved regrind 50% inclusive GF15% reinforced GFR315
Flame retardant,standard,UL approved regrind 50% inclusive GF30% reinforced GFR330
Electric Conductive Unfilled 201EB
For Laser Welding GF30% Reinforced,High transmissibility, Low Warpage 330LW

*grade introduction


  • Automotive connectors

  • Electronic throttle body (ECU case)

  • IH cooking heater

  • Make-up brush

  • Paper laminate (for food)

  • Power supply gun

Product information