Page 177 - Engineering Plastics Handbook

150 Engineering Plastics

ranging from small parts such as connectors to large moldings used in
automotive application. Electrical, automotive, and a variety of other
consumer products benefit from the desirable property combination and
moldability of thermoplastic PBT resins. Unmodified PBT is used in some
applications, but the majority of PBT resins are modified by compound-
ing with various contents of additives such as glass fibers, impact modi-
fiers, flame retardants, and other polymers for various applications.
Selection of the proper type and content of additive makes it possible to
tailor the products to specific customer requirements. Table 7.9 illustrates
the reasons for using PBT resins in various end applications. In many
applications, PBT competes with other thermoplastics such as polyamide,
polyacetal, and polycarbonate resins.

TABLE 7.9 Reasons for Use of PBT in Various Applications
Application Material Reasons for use

Door mirror stay Glass-reinforced Rigidity and hardness
Wire connector Glass/nonreinforced Impact resistance, dimensional
stability
Ignition coil Glass-reinforced, FR* Electrical strength, high HDT
Distributor cap Glass-reinforced, FR Electrical property, rigidity
ABS/ECU housing Glass reinforced, HR † Dimensional stability,
chemical resistance
Bumper fascia PBT/PC alloy Toughness, surface finish
Back beam PBT/PC alloy, impact Low-temperature impact
Door garnish PBT/PC alloy Surface finish, UV stability
Outdoor handle PBT/PC alloy, glass- Toughness, surface finish
reinforced
Head lamp bezel Mineral-reinforced Surface finish, heat resistance
Electric connector Glass/nonreinforced, FR High HDT, stiffness, electrical
property
Coil bobbin Glass-reinforced, FR Dielectric strength, high HDT,
stiffness
Lamp socket Glass-reinforced, FR Heat resistance, UV stability
Switch Glass-reinforced, FR Stiffness, dimensional stability
Relay case Glass-reinforced, FR Heat resistance, stiffness, fluidity
FBT/focus pack Glass-reinforced, FR, HR Heat resistance, stiffness
Motor circuit breaker Glass-reinforced, FR Electrical property, dimensional
stability
Cooling fan Glass-reinforced, FR Heat resistance, dimensional
stability
Optical loose tube Nonreinforced, extrusion Toughness, dimensional stability
Pump case Glass/nonreinforced Chemical resistance, toughness
Hair dryer/steam Glass-reinforced/ Surface finish, temperature
iron nonreinforced resistance
Cooker housing Surface finish, chemical resistance
Oven handle Glass/nonreinforced Surface finish, chemical resistance
* FR: flame-resistant, UL-94 V-0.
†
HR: hydrolysis-resistant.