Pbt Brush Filaments Process Conditions

Drying treatment: this material is easy to hydrolyze at high temperature, so drying before processing is very important. It is suggested that the drying conditions in air are 120, 6~8, or 150, 2~4 hours. Humidity must be less than 0.03%. If dry with hygroscopic dryer, the recommended condition is 150, 2.5 hours. [2]

Melting temperature: 225~275 C, recommended temperature: 250 C.

Mold temperature: for unreinforced material is 40~60 degrees centigrade. The cooling cavity of the die must be well designed to reduce the bending of the plastic parts. The loss of heat must be fast and even. It is suggested that the diameter of the mold cooling cavity is 12mm.

Injection pressure: medium (max to 1500bar).

Injection speed: the speed of injection should be as fast as possible (because the PBT solidifies very quickly).

Runner and gate: circular flow passage is recommended to increase the pressure transfer (empirical formula: runner diameter = plastic thickness +1.5mm). Various types of gates can be used. Hot runner can also be used, but attention should be paid to prevent leakage and degradation of the material. Gate diameter should be between 0.8~1.0*t, where t is the thickness of plastic parts. If it is a submerged gate, it is recommended that the minimum diameter be 0.75mm.

PBT is a straight chain thermoplastic saturated polyester with ester bond in its main chain. Its chemical name is Polybutylene Terephthalte, referred to as PBT. It is a kind of polymer with the same kind as PET resin.

Because of its high melting point and crystallinity, low water absorption coefficient and thermal expansion coefficient, it has excellent dimensional stability. In addition, it has excellent electrical insulation, and the change of electrical properties caused by moisture absorption is very small, and the insulation voltage is very high.

There are crystalline and amorphous regions in the aggregation structure of PBT, so it can be modified easily by adding other materials, giving them various functions. The existing refractory grade, high speed molding grade, high impact grade and so on, gave a variety of functions of various grades.

Connectors, small switch, capacitor shell and other electronic components, OA mechanical keyboard and VTR, telephone and other functional mechanical components, automotive electronic components, door external handle and other automotive parts. In addition, medical machinery, building materials, precision machinery and other widely used in our daily supplies and appliances.


The unreinforced grade is strong and flexible, and has strong brittleness resistance.

The refractory grades (94HB) and self extinguishing grades (94-V-0, V-2) determined by UL specification have the highest electrical properties in thermoplastics.

Very low water absorption, long term use in a wide range of temperature and humidity, but also maintain good electrical properties.

The surface of the molded product is very smooth and has a low coefficient of friction. Because the friction loss is small, it is suitable for the use of friction and wear properties.

The size of the process is very small, and it is a very high reliability material in molding stability and dimensional accuracy.

With good long-term chemical resistance, at room temperature, in addition to strong alkali drugs outside, in which a long time immersion, almost no performance decline occurs.

Not only non enhanced grade, enhanced grade liquidity is also very good, forming processing excellent.

By using the technology of blending with other polymers, a kind of polymer alloy was developed to meet the requirements of various properties.