Warm Global Customers
With China Plastic Machinery
With China Plastic Machinery
PBT plastic is a thermoplastic plastic, the full name is polybutylene terephthalate, which has the characteristics of low water absorption, good electrical properties, and low friction coefficient. It is widely used in parts of electrical appliances, automobiles, mechanical equipment, and precision instruments to replace copper, zinc, aluminum, and cast iron parts.
PBT plastic is made by transesterification and polycondensation of dimethyl terephthalate and 1,4-butanediol under an organic titanium catalyst. It has a fast crystallization speed and better processability than PET. Before modification, PBT has excellent electrical properties and heat resistance, and general mechanical properties; but after being reinforced with 30% glass fiber, its performance increases exponentially, and it has excellent physical properties. It can still maintain the tensile strength of POM at 140¡ãC. PBT plastic has excellent self-lubricity and wear resistance, good heat resistance, and can be used for a long time at 140¡ãC; its thermal expansion coefficient is also one of the smallest varieties among thermoplastic resins. In addition, PBT plastic also has excellent electrical insulation properties, and its chemical resistance stability is similar to that of PET.
Characteristics and Applications of Polybutylene Terephthalate (PBT)
a. Mechanical properties: high strength, fatigue resistance, dimensional stability, small creep (very little change under high temperature conditions);
b. Heat aging resistance: the enhanced UL temperature index reaches 120¡æ¡«140¡æ (long-term outdoor aging is also very good);
c. Solvent resistance: no stress cracking;
d. Water stability: PBT is not easy to decompose when exposed to water;
e. Electrical properties:
1. Insulation performance: excellent (it can maintain stable electrical properties even in humidity and high temperature, and is an ideal material for manufacturing electronic and electrical parts);
2. Dielectric constant: 3.0-3.2;
3. Arc resistance: 120s
f. Molding processability: injection molding or extrusion molding with ordinary equipment. Due to its fast crystallization speed and good fluidity, the mold temperature requirement is lower than that of other engineering plastic. When processing thin-walled parts, it only takes a few seconds, and for large parts, it only takes 40-60s.
\ra, Electronics and electrical appliances: connectors, switch parts, household appliances, accessories, small electric covers or (heat resistance, flame retardancy, electrical insulation, molding processability);
b, Automobile:
1. Exterior parts: mainly corner grilles, engine heat release hole covers, etc.;
2. Internal parts: mainly endoscope stays, wiper brackets and control system valves;
3. Automotive electrical parts: automotive ignition coil twisted tubes and various electrical connectors, etc.
(The number of PBT used in automobiles is not as large as nylon, polycarbonate and polyoxymethylene, but with the emergence of low-warpage PBT, it will be more widely used in automobile parts in the future)
c. Mechanical equipment: video tape recorder belt drive shaft, computer cover, mercury lamp cover, electric iron cover, baking machine parts and a large number of gears, cams, buttons, electronic watch housings, camera parts (heat-resistant and flame-retardant requirements)
According to different needs, the following adhesives can be selected:
1.TG-3200: single-component room-temperature curing soft elastic shockproof adhesive, resistant to high and low temperatures, but slow bonding speed, the glue usually takes 1 day or several days to cure.
2.TS-8602 instant adhesive, which can quickly bond PBT in a few seconds or tens of seconds, but the adhesive layer is hard and brittle and not water-resistant.
3.TE-9270 type, two-component adhesive, soft adhesive layer, suitable for large-area bonding or compounding of PBT. But the high temperature resistance is poor.
4.TE-9249 type adhesive: two-component adhesive, high temperature resistance.
5.sili-1706: single-component room temperature vulcanized adhesive, after curing, it is an elastomer with excellent waterproof and shockproof adhesive, high and low temperature resistance, 1-2mm thickness, 5-6 hours basic curing, with certain strength. It takes at least 24 hours to fully cure. Single component, no need to mix, just apply and let stand after extrusion, no need to heat.
PBT must be dried at 110¡æ¡«120¡æ for about 3 hours before injection molding, the molding temperature is 250¡æ¡«270¡æ, and the mold temperature is preferably controlled at 50¡æ¡«75¡æ. Since the material will solidify and crystallize immediately after cooling from the molten state, its cooling time is short; if the nozzle temperature is improperly controlled (low), the runner (gate) is easy to cool and solidify, and the nozzle will be blocked. If the barrel temperature exceeds 275¡ãC or the molten material stays in the barrel for more than 30 minutes, it is easy to cause the material to decompose and become brittle. When PBT is injected, a larger gate is required for injection. It is not suitable to use a hot runner system. The mold exhaust should be good. It is suitable to use "high speed, medium pressure, medium temperature" conditions for molding and processing. Fireproof materials or glass fiber-added PBT gate materials should not be recycled. When the machine is stopped, PE or PP materials should be used to clean the material pipe in time to avoid carbonization.
PBT polybutylene terephthalate chemical and physical properties PBT is one of the toughest engineering thermoplastic materials. It is a semi-crystalline material with very good chemical stability, mechanical strength, electrical insulation properties and thermal stability. These materials have good stability under a wide range of environmental conditions.
PBT has very weak hygroscopic properties. The tensile strength of non-reinforced PBT is 50MPa, and the tensile strength of glass additive PBT is 170MPa. Too much glass additive will cause the material to become brittle. PBT crystallizes very quickly, which will cause bending deformation due to uneven cooling; for materials with glass additives, the shrinkage rate in the process direction can be reduced, but the shrinkage rate in the direction perpendicular to the process is basically the same as that of ordinary materials. The shrinkage rate of general materials is between 1.5% and 2.8%, and the shrinkage rate of materials containing 30% glass additives is between 0.3% and 1.6%. The melting point (225%¡æ) and high temperature deformation temperature are lower than those of PET materials. The Vicat softening temperature is about 170¡æ, and the glass transition temperature (glass transition temperature) is between 22¡æ and 43¡æ. Due to the high crystallization rate of PBT, its viscosity is very low, and the cycle time of plastic parts processing is generally low.
1. PBT intermittent type, Polytex Design, PTA route synthesis method or DMT route synthesis method (English: Batch-poly)
2. PBT continuous type, Polytex Design, PTA route synthesis method.
Process description:
1. 1-4 butanediol mixing and delivery system
2. Slurry preparation system
3. Esterification reaction system
4. Process tower system
5. Pre-condensation reaction system
6. Pre-condensation filtration system
7. Final condensation reaction system
8. Final condensation filtration system
9. Slicing, pelletizing and packaging system
10. Catalyst preparation and continuous addition control system
11. Filter cleaning system
12.THF recovery system
13.Heat medium system
14.Computer integrated control system
Features:
1.Low temperature, low molar ratio, mild reaction
2.Reliable residence time
3.Maintain reasonable material consumption at different reaction stages
4.Low consumption, energy saving, economy
5.Good melt rheology
Design scale:
The production capacity of the industrially produced POLYTEX technology continuous unit is from 30 tons/day to 500 tons/day, that is, 10,000 tons to 150,000 tons per year.
Process description:
1. 1-4 butanediol mixing and delivery system
2. Premelt preparation system
3. Esterification reaction system
4. Polycondensation reaction system
5. Slicing, pelletizing and packaging system
6. Catalyst preparation system
7. Filter cleaning system
8. THF recovery system
9. Heat medium system
10. Computer integrated control system
Features:
1. The slurry preparation system is used in the production of modified PBT, and the catalyst and additives can be added at low temperature
2. Esterification is continuously fed at low temperature or normal reaction temperature, which is easy to control, safe and reliable
Design scale:
The industrial design single-line capacity is 3-40 tons/day, with an annual output of 1,000 tons to 15,000 tons.
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