PC plastics will break bonds by hydrolysis, decrease molecular weight and decrease mechanical properties even if they encounter very low moisture. Therefore, before the molding process, the moisture of polycarbonate should be strictly controlled below 0.02% to avoid the reduction of mechanical properties of the molding product or the abnormal appearance of bubbles, silver lines, etc.

In order to avoid abnormal situations caused by moisture, polycarbonate should be dried by hot air dryer for more than three to five hours before processing, and the temperature is set at 120 ° C, or by dehumidifying dryer to treat moisture, but the dehumidifying air should have a dew point of -30 ° C at the entrance of the funnel.

To meet the needs of various injection molding processes, polycarbonate has different melting index specifications. Generally, the melting index between 5 and 25g/10min is suitable for injection molding. However, the optimum processing conditions are quite different due to the type of injection molding machine, the shape of the molding product and the specifications of polycarbonate, and should be adjusted according to the actual situation.

First, injection molding machine selection points

1. Clamping pressure

Multiply the projected area of the finished product by 0.47 to 0.78旽 per square centimeter (or 3 to 5 tons per square inch).

2. Machine size

The weight of the finished product is about 40% to 60% of the capacity of the injection molding machine, such as the machine to polystyrene to express its capacity (Oz), need to reduce 10%, 1 oz =28.3 grams.

3. Screw

The screw length should be at least 15 diameters long, and its L/D is 20:1. The optimal compression ratio should be 1.5:1 to 30:1. The stop valve at the front end of the screw should be a sliding ring type, and the resin flow gap should be at least 3.2mm.

Step 4: Nozzle

The tip opening should be at least 4.5mm(diameter), and if the weight of the finished product is more than 5.5kg, the nozzl