Polybutylene Terephthalate (PBT) is a thermoplastic polyester produced by the polycondensation of 1,4-Butanediol (BDO) and Terephthalic Acid (PTA). Its CAS Number is 26062-94-2.
PBT appears as white to off-white pellets or granules, offering low moisture absorption, rapid crystallization, and excellent processability via injection molding or extrusion.

Compared to PET (Polyethylene Terephthalate), PBT features a longer butylene chain, resulting in faster crystallization rates, better impact toughness, lower processing temperatures, and superior dimensional stability in humid conditions, though PET generally provides higher stiffness and heat deflection temperature.

Polybutylene Terephthalate (PBT), a crystalline engineering polyester renowned for its excellent mechanical strength, dimensional stability, chemical resistance, and electrical insulation properties. Ideal for demanding applications in automotive, electrical & electronics, and industrial sectors.

 

Technical Specifications

ITEMS UNIT 2075 2080 2083 2085 2090 2100 2100F 2110 2115 2120 2125T 2130
Intrinsic Viscosity dL/g 0.725±0.012 0.775±0.012 0.830±0.012 0.825±0.012 0.870±0.012 1.000±0.012 0.990±0.012 1.070±0.015 1.20±0.015 1.165±0.015 1.193±0.015 1.230±0.020
Carboxyl End Groups mol/t 14.0±4.0 14.0±4.0 14.0±4.0 14.0±4.0 14.0±4.0 16.0±4.0 20.0±4.0 22.0±4.0 22.0±4.0 26.0±4.0 26.0±3.0 26.0±4.0
Color L Value – ≥95 ≥95 ≥95 ≥95 ≥95 ≥95 ≥95 ≥95 ≥95 ≥95 ≥95 ≥95
Color B Value – 2.0±1.0 2.0±1.0 2.0±1.0 2.0±1.0 2.0±1.0 2.0±1.0 2.0±1.0 3.0±1.0 3.0±1.0 3.0±1.0 3.0±1.0 3.0±1.0
Moisture Absorption % ≤0.2 ≤0.2 ≤0.2 ≤0.2 ≤0.2 ≤0.2 ≤0.2 ≤0.2 ≤0.2 ≤0.2 ≤0.2 ≤0.2
Density g/cm³ 1.30-1.32 1.30-1.32 1.30-1.32 1.30-1.32 1.30-1.32 1.30-1.32 1.30-1.32 1.30-1.32 1.30-1.32 1.30-1.32 1.30-1.32 1.30-1.32
Melting Flow Rate (235℃/2.16kg) g/10min 87.0±8.0 61.0±5.0 51.0±4.0 45.0±4.0 33.0±4.0 19.0±3.0 18.0±3.0 13.0±3.0 11.0±3.0 8.5±2.0 7.0±2.0 5.5±2.0
Melting Flow Rate (250℃/2.16kg) g/10min 125±10.0 92.0±6.0 75.0±5.0 69.0±5.0 50.0±4.0 30.0±3.0 29.0±3.0 19.0±3.0 16.0±3.0 13.0±3.0 11.0±2.0 9.0±2.0
Tensile Strength (50mm/min) MPa ≥50 ≥50 ≥50 ≥50 ≥50 ≥50 ≥50 ≥50 ≥50 ≥50 ≥50 ≥50
Break Elongation % ≥20 ≥30 ≥40 ≥50 ≥70 ≥100 ≥100 ≥150 ≥200 ≥250 ≥250 ≥250
Flexural Strength MPa ≥70 ≥70 ≥70 ≥70 ≥70 ≥70 ≥70 ≥65 ≥60 ≥60 ≥60 ≥60
IZOD Notched Impact Strength kJ/M² ≥3.0 ≥3.0 ≥4.0 ≥4.0 ≥5.0 ≥6.0 ≥7.0 ≥7.0 ≥7.0 ≥7.0 ≥7.0 ≥7.0

 

Key Benefits and Properties of Polybutylene Terephthalate (PBT)

Mechanical Strength:
High tensile strength, rigidity, and creep resistance, with good impact toughness (especially in reinforced grades).

Thermal Stability:
Continuous use temperature up to 140°C; high heat distortion temperature (HDT), particularly in glass-fiber reinforced versions.

Electrical Properties:
Excellent dielectric strength and insulation, making it suitable for UL-rated components.

Chemical Resistance:
Resistant to automotive fluids, solvents, oils, and many chemicals; good hydrolysis resistance in stabilized grades.

Dimensional Stability:
Low moisture absorption and minimal warpage, ensuring precision in molded parts.

Processing Advantages:
Fast crystallization for short cycle times, good surface finish, and paintability/printability.

Other:
Weathering resistance, low friction, and flame-retardant options available.

 

Applications of Polybutylene Terephthalate (PBT)

PBT is widely used across industries where durability, precision, and performance under stress are critical:

Automotive Industry

  • Connectors, sensors, fuse boxes, wire harnesses, and under-the-hood components.
  • Interior and exterior parts requiring resistance to heat, vibration, and chemicals.

Electrical and Electronics

  • Insulators, housings for switches, relays, circuit breakers, and power tools.
  • Connectors and components in consumer electronics and lighting systems.

Industrial and Consumer Goods

  • Appliance parts (e.g., irons, showerheads), food processing equipment (FDA-compliant grades), and mechanical components.
  • Keycaps for high-end keyboards and other wear-resistant parts.

 

Frequently Asked Questions (FAQs)

Q: Is PBT the same as PET?
A: No. While both are polyesters, PBT has a longer chain (butylene vs. ethylene), leading to faster crystallization, better processability, and improved toughness, while PET offers higher stiffness and is more common in packaging.

Q: What are the main applications of PBT?
A: PBT is primarily used in automotive connectors, electrical insulators, switches, appliance parts, and food processing equipment due to its heat resistance, electrical properties, and chemical stability.

Q: Is PBT food safe?
A: Certain grades of PBT comply with FDA regulations for indirect food contact applications, such as food processing equipment. Always verify the specific grade.

Q: Can PBT be flame retardant?
A: Yes, specialized flame-retardant grades are available to meet UL94 V-0 or other standards for electrical safety.

 

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