Application of the hottest technology on PC

  • Detail

The application of technology on PC

PPC is generally known as polycarbonate, which is commonly known as bulletproof glue because of its excellent mechanical properties. PC has the characteristics of high mechanical strength, wide temperature range, good electrical insulation (but the anti arc performance remains the same), good dimensional stability, transparency and so on. It is widely used in electrical products, electrical instrument shells, and structural parts of electronic products. There are many modified products of PC, such as adding glass fiber, mineral filler, chemical flame retardant, other plastics, etc. PC has poor fluidity and high processing temperature, so the processing of many levels of modified materials requires special plasticizing injection structure

1. Plastic treatment

pc has high water absorption. It must be preheated and dried before processing. Pure PC is dried at 120 ℃, and modified PC is generally dried at 110 ℃ for more than 4 hours. The drying time should not exceed 10 hours. Generally, the air-to-air extrusion method can be used to judge whether the drying is sufficient

the proportion of recycled materials can reach 20%. In some cases, 100% recycled materials can be used, and the actual amount depends on the quality requirements of the products. Recycled materials cannot be mixed with different color masterbatches at the same time, otherwise the properties of finished products will be seriously damaged

2. Selection of injection molding machine

due to the cost and other reasons, the current PC products use more modified materials, especially electrical products, but also need to increase the fire resistance. When the flame-retardant PC and other plastic alloy products are molded, the requirements for the plasticizing system of the injection molding machine are good mixing and corrosion resistance, and the conventional plasticizing screw is difficult to achieve. When purchasing, we must explain in advance the organization of Beijing Tianjin Hebei, changsanjiao A total of 23000 people from nearly 10000 enterprises in the Pearl River Delta participated in the cleaner production capacity improvement training. Ramada has special PC screws for customers to choose from

3. Mold and gate design

common mold temperature is ℃, plus glass fiber is ℃, small products can use needle gate, the gate depth should be 70% of the thickest part, and other gates have ring and rectangle

the larger the gate, the better, so as to reduce the defects caused by excessive shearing of plastic

the depth of the exhaust hole should be less than 0 06mm, the runner shall be as short and round as possible

generally, the demoulding slope is above 6 points, which is about 30 -1 for the maintainability of the plunger pump

4. Melt temperature

the processing temperature can be determined by air injection. Generally, the processing temperature of PC is ℃, and that of some modified or low molecular weight PC is ℃. Looking forward to 2014

5, injection speed

it is common to use faster injection speed for molding, such as electric switch components. Slow rapid prototyping is common

6. The back pressure

10bar can be appropriately reduced in the absence of wrinkles and color mixing

7. Residence time

if the residence time at high temperature is too long, the material will degrade, release CO2 and turn yellow. Do not use LDPE, POM, ABS or PA to clean the barrel. Apply PS cleanup

8. Precautions

some modified PCs are prone to dark brown liquid bubbles due to too many recovery times (reduced molecular weight) or uneven mixing of various components

Copyright © 2011 JIN SHI