PBT engineering plastics, (polybutylene terephthalate), has excellent comprehensive performance, relatively low price, and has good molding processing. In electronics, electrical appliances, mechanical equipment, automotive and precision instruments and other fields, it has been widely used.
Characteristics of modified PBT
(1) Excellent mechanical properties, high strength and fatigue resistance, good dimensional stability and small creep. Under high temperature conditions, the performance changes less.
(2) Easy flame retardant, and flame retardant has a good affinity, easy to develop added type and reaction type flame retardant grade, can meet the requirements of UL94 V-0 grade. It has been widely used in electronics and electrical industry.
(3) Heat resistance, aging resistance, organic solvent resistance. The enhanced UL temperature index is maintained in the range of 120 ° C to 140 ° C, and all of them have good outdoor long-term aging.
(4) Good processing performance. Easy to secondary processing and molding processing, with the help of ordinary equipment can be extrusion molding or injection molding; It has fast crystallization rate and good fluidity, and the mold temperature is relatively low
Modification direction of PBT
1. Enhancement modification
In the PBT added glass fiber, glass fiber and PBT resin bonding force is good, in the PBT resin added a certain amount of glass fiber, not only can maintain the PBT resin chemical resistance, processing and other original advantages, but also can have a relatively large increase in its mechanical properties, and overcome the PBT resin notch sensitivity.
2. Flame retardant modification
PBT is a crystalline aromatic polyester, without flame retardant, its flame retardant is UL94HB, only after the addition of flame retardant, can reach UL94V0.
Commonly used flame retardants have bromide, Sb2O3, phosphide and chloride halogen flame retardants, such as the most is ten bromine biphenyl ether, has been the major PBT, flame retardant, but due to environmental protection, European countries have long bans the use, the parties are looking for the replacement, but have no performance advantage has been more than ten bromine biphenyl ether substitutes.
3. Modification of blending alloy
The main purpose of PBT blending with other polymers is to improve the notched impact strength, improve the warping deformation caused by molding shrinkage, and improve the heat resistance.
Blending is widely used to modify it at home and abroad. The main modified polymers used for PBT blending are PC, PET, etc. This kind of products are mainly used in automobiles, electronics and power tools. The proportion of glass fiber is different, and its application field is also different.
Main applications of PBT materials
1. Electronic appliances
No fuse breaker, electromagnetic switch, drive back transformer, home appliance handle, connector, etc. PBT is usually added 30% glass fiber mixing as connector, PBT is widely used because of mechanical properties, solvent resistance, forming processing and low price.
2. Heat dissipation fan
Glass fiber reinforced PBT is mainly used in the heat dissipation fan, the heat dissipation fan is placed in the machine for a long time to help heat dissipation, the physical properties of plastic requirements have heat resistance, flammability, insulation and mechanical strength, PBT is usually in the form of 30% fiber applied as the heat dissipation fan outside the frame and fan blade coil shaft.
3. Electrical components
Glass fiber reinforced PBT is also used as a transformer, relay inside the coil shaft, generally PBT plus fiber 30% injection forming. The required physical properties of the coil shaft include insulation, heat resistance, welding resistance, fluidity and strength, etc. The suitable materials are GLASS fiber reinforced PBT, GLASS FIBER reinforced PA6, GLASS FIBER reinforced PA66, etc.
4. Automotive parts
A. External parts: mainly car bumper (PC/PBT), door handle, corner lattice, engine heat release hole cover, car window motor shell, fender, wire cover, wheel cover car transmission gear box, etc.
B. Internal parts: mainly include endoscope brace, wiper bracket and control system valve;
C, automotive electrical parts: automotive ignition coil twist tube and various electrical connectors, etc.
At the same time, it can also be applied to the charging gun shell of new energy vehicles.
5. Mechanical equipment
PBT material is also widely used in video tape recorder belt drive shaft, computer cover, mercury lampshade, iron cover, baking machine parts and a large number of gear, CAM, button, electronic watch housing, camera parts (with heat, flame retardant requirements)
SIKOPOLYMERS’ Main grades of PBT and their description, as following: