What are the mechanical features of the Two-color Clear PC tube?
The two-color polycarbonate tube has the characteristics of high mechanical strength, wide application temperature range, good electrical insulation function, good dimensional stability, and transparency. It is widely used in electrical products, electrical instrument housings, and electronic product structures. There are many modified products of polycarbonate two-color tubes with additives such as glass fiber, mineral fillers, chemical flame retardants, and other plastics. The PC double-color tube has poor fluidity and high processing temperature, so the processing of many grades of modified materials requires a special plastic injection structure.
The Two-color Clear PC tube design and manufacturing requirement.
1. Treatment of plastic resin
Two-color Clear PC tube has a high water absorption rate. It is required to be preheated and dried before processing. A pure PC two-color tube is dried at 120°C, and the modified PC two-color pipe is usually dried at 110°C for more than 4 hours. The dull moment cannot exceed 10 hours. The air extrusion method can usually be used to judge whether boring is satisfied.
The utilization share of recycled materials can reach 20%. In some cases, 100% of recycled materials can be used, and the actual amount depends on the quality requirements of the finished product. Recycled materials cannot be mixed with different masterbatches, otherwise, the properties of the finished product will be severely damaged.
2. Selection of the extruder
Today’s Two-color Clear PC tube products are mostly made of modified plastics, especially electrical products, because of cost and other factors. Fire protection must be added. When the flame-retardant PC two-color pipes are molded together with other plastic alloys, the extruder If the plasticizing system is well-mixed and corrosion-resistant, the conventional plasticizing screw is difficult to achieve. When purchasing, it must be stated in advance.
3, Extrusion dies and gate design
The common mold temperature is 80-100°C, and the glass fiber is 100-130°C. Pin gates can be used for small finished products, and the gate depth should be 70% of the thickest part. Other gates have rings and rectangles.
The larger the gate, the better, to reduce the disadvantages of plastic being over-sheared.
The depth of the exhaust hole should be less than 0.03-0.06mm, and the runner should be as short and round as possible.
The draft angle is usually 30′-1°.
4, melting temperature
Usually, the processing temperature of the PC double color tube is 270-320℃, and some modified or low molecular weight PC double color tube is 230-270℃.
5, Extrusion speed
It is often used for molding with a faster injection speed, such as electrical switch parts. More common is slow → rapid forming.
6, back pressure
The back pressure around 10bar can be appropriately lowered without airlines and color mixing.
7, stay time
If the residence time is too long under high temperature, the material will be degraded, CO2 will be released, and it will become yellow. Do not use LDPE, POM, ABS, or PA to finish the barrel, but PS for finishing.
8. More attention
Some modified Two-color Clear PC tube is easy to produce dark brown liquid bubbles because of too many withdrawal times (decreased molecular weight) or uneven mixing of various components.