Advantages, Disadvantages and Applications of PC Materials

Advantages and disadvantages of PC materials:

Polycarbonate is colorless, transparent, heat resistant, impact resistant, flame retardant BI grade, and has good mechanical properties at normal use temperatures. Polycarbonate has good impact resistance, high refractive index, good processing performance, and UL94 V-0 flame retardant performance without additives. The main performance defect of PC is that the hydrolysis resistance is not high enough, it is sensitive to the notch, resistant to organic chemicals, and has poor scratch resistance. It will yellow when exposed to ultraviolet light for a long time. PC, like other resins, is susceptible to attack by certain organic solvents. Polycarbonate has poor wear resistance and some polycarbonate devices for wear and tear require special handling of the surface.

Processing conditions of PC (polycarbonate):

Polycarbonate has excellent overall properties and is particularly suitable for the manufacture of small parts with precise dimensions, complex shapes, light loads or less impact loads. During the processing, the viscosity decreases with the increase of temperature, and it is necessary to strictly control the three conditions of raw material drying, injection temperature and mold temperature.

(1) Drying of raw materials

The most prominent of polycarbonate is the sensitivity to trace moisture at high temperatures. In addition, the melting temperature is high, the melt viscosity is large, and cracking and other quality accidents are often caused by improper handling. Therefore, it must be dried strictly and thoroughly before injection molding. After drying, the moisture content of the plastic should not exceed 0.02%. The presence of trace moisture can cause destructive degradation of the polycarbonate, decrease the viscosity, release carbon dioxide and other gases, discolor the plastic, and deteriorate the performance. The injected optical disc product is easy to bring silver wire, air bubbles, and even cracks. The higher the moisture content, the more severe the destructive degradation.

(2) Injection temperature

Polycarbonate has two hot working properties: high thermal stability and a wide range of molding temperatures; large changes in viscosity due to temperature changes, and small changes in viscosity due to changes in shear rate.

That is, the melt flowability of polycarbonate (PC) is greatly affected by temperature changes, and the effect of pressure is not significant. Therefore, the adjustment of the injection temperature has always been an effective means to smoothly shape and control the quality of the parts.

However, if the temperature is too low, the viscosity is too large, and the supply is insufficient, the surface of the part will shrink, wrinkle, dull, and the silver wire will be disordered; if the temperature is too high or higher than 320 ° C and the residence time is too long, it will cause serious degradation. The workpiece has a flash edge, a dark brown color, a silvery dark strip on the surface, spots and traces, and bubbles inside, and the physical properties are greatly reduced.

(3) mold temperature

Polycarbonate has high viscosity, poor fluidity, is insensitive to shearing action, and has a fast cooling rate, which easily causes defects on the surface of the part to form internal stress.

If the mold temperature is too low, the workpiece is difficult to fill the cavity, or has obvious shrinkage, ripples, hair spots, dark stripes, voids and other apparent defects, which will increase the residual of the workpiece.

If the mold temperature is too high, the parts are cooled slowly, the molding cycle is long, the surface gloss is poor, and the sticking mold is caused, which makes it difficult to eject and demold, and the bridge area and warpage are deformed.

Injection pressure of PC (polycarbonate):

The influence of injection pressure on the performance of the part is mainly reflected in the holding time. The holding time is short, the parts shrink, or shrinkage voids, vacuum bubbles; lengthening the holding time, especially for large-area thick-walled parts, can increase its density, eliminate vacuum holes, improve dimensional stability; Will cause internal stress in the part and it is easy to crack.

PC (polycarbonate) application:

PC is widely used in packaging / building materials, automotive, medical, aerospace, aerospace, electronics, glasses and other fields.

Packaging: A new growth in the packaging sector is the various types of water bottles that can be resterilized and used. The use of PC bottles is common because polycarbonate products have the advantages of light weight, good impact resistance and transparency, and are not deformed and kept transparent when washed with hot water and corrosive solutions.

Building materials industry: PC sheet has good light transmission, impact resistance, dimensional stability, molding processability and UV resistance, and has obvious technical performance advantages over traditional inorganic glass.

Automotive: Polycarbonate has good impact resistance and thermal distortion resistance, and it has good weather resistance and high hardness. Therefore, it is suitable for the production of various parts for cars and light trucks. Its applications are mainly concentrated in lighting systems and dashboards. A heating plate, a defroster, and a bumper made of polycarbonate alloy.

Medical devices: Because PC products can withstand steam, cleaning agents, heating and high-dose radiation disinfection, and do not yellow and physical properties, they are widely used in artificial kidney hemodialysis equipment and other operations that need to operate under transparent and intuitive conditions. And need to be repeatedly disinfected in medical equipment. Such as the production of high-pressure syringes, surgical masks, disposable dental appliances, blood separators and so on.

Aerospace: With the rapid development of aviation and aerospace technology, the requirements for various components in aircraft and spacecraft are constantly increasing, and the application of PC in this field is also increasing. According to statistics, there are 2,500 polycarbonate parts used on only one Boeing aircraft, and about 2 tons of polycarbonate is used in a single machine. On the spacecraft, hundreds of polycarbonate components with different configurations and enhanced by glass fibers and protective equipment for astronauts are used.

CD-ROM: The amount of PC materials consumed by the world's optical disc manufacturing industry has exceeded 20% of total PC consumption and is growing at an extremely fast rate.

Electronics: Because polycarbonate has good and constant electrical insulation over a wide range of temperature and humidity, it is an excellent insulating material. At the same time, due to its good flame retardancy and dimensional stability, it is widely used in the electronic and electrical industry, including power tool casings, bodies, brackets, refrigerator freezer drawers and vacuum cleaner parts. There are also many applications of PC materials in terms of important components in computers, video recorders, and color TV sets.

Optical Lenses: Polycarbonate occupies an extremely important position in this field due to its unique high light transmittance, high refractive index, high impact resistance, dimensional stability and easy processing. Optical lenses made of optical grade polycarbonate can be used not only in cameras, microscopes, telescopes, optical test instruments, but also in film projector lenses, copier lenses, infrared autofocus projector lenses, laser beam printer lenses, and Kinds of prisms, multi-faceted mirrors and many other office equipment and home appliances. In the optical industry, PC materials are also used for lens materials for children's glasses, sunglasses, safety glasses and adult glasses.

CD-ROM: The amount of PC materials consumed by the world's optical disc manufacturing industry has exceeded 20% of total PC consumption and is growing at an extremely fast rate.