Polycarbonate (PC for short), also known as PC plastic; is a polymer containing carbonate groups in the molecular chain, which can be divided into aliphatic, aromatic, aliphatic-aromatic and other types according to the structure of the ester group. Of these, aliphatic and aliphatic-aromatic polycarbonates have low mechanical properties, thus limiting their use in engineering plastics.
Only aromatic polycarbonates have been industrially produced. Due to its structural peculiarities, polycarbonate has become the fastest growing general engineering plastic among the five major engineering plastics.
Chinese name Polycarbonate  Foreign name Polycarbonate Alias PC plastic  Melting point 220 to 230 °C Water soluble insoluble density 1.2 g/cm³ Safety description inedible available temperature -40 °C to +135 °C heat deflection temperature 135 °C yield 1.585 ± 0.001 light transmission rate 90% ± 1% thermal conductivity 0.19 W/mK linear expansion rate 3.8 x 10-5 cm/cm°C
Polycarbonate is a strong thermoplastic resin that derives its name from its internal groups. It can be synthesised from bisphenol A and carbonyl chloride (COCl2). The most commonly used method is the molten ester exchange method (bisphenol A and diphenyl carbonate are synthesised by an ester exchange and condensation reaction).
Polycarbonate (PC) is a polyester type of carbonic acid, which is not stable by itself, but its derivatives (e.g. phosgene, urea, carbonate, carbonate) are stable.
Polycarbonates can be divided into two groups, aliphatic and aromatic, depending on the alcohol structure.
Aliphatic polycarbonates. For example, polyethylene-carbonate, polytrimethylene-carbonate and their copolymers have low melting and glass transition temperatures and poor strength, and cannot be used as structural materials; however, their biocompatibility and biodegradable properties can be used in drug slow release carriers, surgical sutures, bone support materials and other applications.
Polycarbonate is resistant to weak acids, weak bases and neutral oils.
Polycarbonate is not resistant to UV light or strong alkalis.
PC is a linear carbonated polyester with alternating carbonic acid groups in the molecule with other groups which can be aromatic, aliphatic or both. Bisphenol A type PC is the most important industrial product.
PC is an almost colourless, glassy, amorphous polymer with good optical properties. PC high molecular weight resins have a high toughness, with a cantilever beam notched impact strength of 600-900 J/m. The heat deflection temperature of unfilled grades is approximately 130°C, and glass fibre reinforcement increases this value by 10°C. The bending modulus of PC can be over 2400 MPa, and the resin can be processed into large rigid products. The creep rate under load is very low below 100°C. PC is poorly resistant to hydrolysis and cannot be used for products that are repeatedly subjected to high pressure steam.
The main shortcomings of PC are its lack of hydrolytic stability, sensitivity to chipping, resistance to organic chemicals, poor scratch resistance and yellowing on long-term exposure to UV light. Like other resins, PC is susceptible to attack by certain organic solvents.
PC materials are flame retardant. Resistant to oxidation.
Polycarbonate tubes (2 sheets)
Density: 1.18-1.22 g/cm3 Linear expansion: 3.8 x 10-5 cm/°C Heat deflection temperature: 135°C Low temperature -45°C
Polycarbonate is colourless, transparent, heat resistant, impact resistant, flame retardant BI grade and has good mechanical properties at all common service temperatures. Compared with polymethyl methacrylate, polycarbonate has good impact resistance, a high refractive index, good processing properties and is UL94 V-2 flame retardant without the need for additives. However, polymethyl methacrylate is less expensive than polycarbonate and can be produced in large devices by ontogenic polymerisation.
The abrasion resistance of the material is relative and when comparing ABS with PC, it is the PC material that is more abrasion resistant. However, compared to most plastic materials, polycarbonate is relatively poor in terms of abrasion resistance, and therefore some polycarbonate devices for abrasion-prone applications require special surface treatment.
Anti-static PC, conductive PC, fibre reinforced fire resistant PC, UV resistant weather resistant PC, food grade PC, chemical resistant PC.
1. mechanical properties: with high strength and elasticity coefficient, high impact strength, good fatigue resistance, good dimensional stability, also small creep (very little change even under high temperature conditions), high transparency and free colouring.
2. heat aging resistance: a wide range of use temperature, enhanced UL temperature index of 120 ~ 140 ℃ (outdoor long-term aging is also very good).
3. solvent resistance: no stress cracking.
4. stability to water: easy to decompose under high temperature in contact with water (caution is needed when using in high temperature and high humidity environment)
5. insulating properties: excellent (moisture, high temperature can also maintain the electrical properties of stable, is the ideal material for the manufacture of electronic and electrical parts).
6. dielectric coefficient: 3.0-3.2.
7. arc resistance: 120s.
8. molding processability: common equipment injection or extrusion.
Bonding of PC plastics
Depending on the needs, the following adhesives can be selected.
1. G-933: one-component, room temperature curing, soft and flexible anti-shock adhesive, resistant to high and low temperatures, curing in seconds to a few hours at different viscosities.
2. KD-833: instant adhesive, can quickly bond PC plastics in seconds or tens of seconds, but the adhesive layer is hard and brittle and not resistant to hot water immersion above 60 degrees.
3. QN-505 is a two-component adhesive with a soft adhesive layer, suitable for bonding or laminating PC plastics in large areas. But the high temperature resistance is poor.
4. QN-906: two-component adhesive, high temperature resistance.
5. G-988: one-component room temperature vulcanisation adhesive, after curing is an elastomer with excellent waterproof, shockproof adhesive, high and low temperature resistance, 1-2mm thickness, about 10 minutes initial solidification, 5-6 hours basic curing, there is a certain strength. It takes at least 24 hours to fully cure. Single component, no mixing required, just apply after extrusion and leave to set, no need to add heat.
6. KD-5606: UV curing adhesive, bonding transparent PS sheet and plate, can achieve the effect of no traces, need to be cured by UV light. Sticky after the effect of beautiful. But the high temperature resistance is poor.
The three main areas of application for PC engineering plastics are the glass assembly industry, the automotive industry and the electronics and electrical industry, followed by industrial machinery parts, CD-ROMs, packaging, computer and other office equipment, medical and healthcare, film, leisure and protective equipment, etc. PC can be used as window and door glass, PC laminates are widely used in banks, embassies, detention facilities and public places for protective windows, for aircraft hatches, lighting equipment, industrial security stalls and bullet-proof glass.
PC sheets can be used for various signage such as petrol pump dials, car dashboards, cargo and open-air commercial signage, point sliding indicators, PC resin for automotive lighting systems, dashboard systems and interior trim systems, as headlight covers, front and rear gear panels for cars with reinforcement, reflector frames, door frame covers, lever guards, flow stoppers, PC is used as junction boxes, sockets, plugs and sleeves, gaskets, TV conversion PC is used as low load parts for household appliance motors, vacuum cleaners, hair washers, coffee machines, toasters, handles for power tools, various gears, worm gears, bushings, guide gauges, shelves in refrigerators. PC is an ideal material for disc storage media.
PC bottles (containers) are transparent, light weight, good impact resistance, resistant to certain high temperatures and corrosive solution washing, as recyclable bottles (containers). PC and PC alloys can be used for computer racks, housings and auxiliary machines, printer parts. Modified PC is resistant to high energy radiation sterilisation, steaming and baking disinfection, and can be used for blood specimen collection apparatus, blood oxygenators, surgical instruments, kidney dialysis apparatus, etc. PC can be used for helmets and helmets, protective masks, sunglasses and sports eye protectors. PC films are widely used for printing charts, pharmaceutical packaging, and film commutators.
Polycarbonate application development is to high composite, high function, specialization, series direction, has launched a variety of products such as CD-ROM, automotive, office equipment, boxes, packaging, medicine, lighting, film, etc. each special grade brand.
Building materials industry
Polycarbonate sheets have good light transmission, impact resistance, UV radiation resistance and the dimensional stability of its products and good molding and processing properties, making it a significant technical performance advantage over the traditional use of inorganic glass in the construction industry. China has built more than 20 polycarbonate building materials hollow sheet production lines, the annual need for polycarbonate about 70,000 tons, to reach 140,000 tons in 2005.
Automobile manufacturing industry
Polycarbonate has good impact resistance, thermal distortion resistance, and good weather resistance, high hardness, so it is suitable for the production of cars and light trucks of various parts, its main focus on lighting systems, instrument panels, heating panels, defrosters and polycarbonate alloy bumper, etc..
Syringes made from medical grade PC
Syringes made from medical grade PC
According to the data of developed countries, the proportion of polycarbonate used in electrical and electronic and automobile manufacturing industries is 40% to 50%, and the proportion of China’s use in this field is only about 10%. The total number of cars in China is large and the demand is high, thus the application of polycarbonate in this field is extremely potential for expansion.
Polycarbonate products are widely used in artificial kidney haemodialysis equipment and other medical devices that need to be operated under transparent, intuitive conditions and repeatedly sterilised, as they can be sterilised by steam, detergents, heating and high doses of radiation without yellowing or deterioration of physical properties. Examples include the production of autoclave syringes, surgical masks, disposable dental appliances, blood separators, etc.
With the rapid development of aviation and aerospace technology, the requirements for various components in aircraft and spacecraft are increasing, making the application of PC in this field also increasing day by day. According to statistics, only one Boeing-type aircraft used polycarbonate parts up to 2,500, single machine consumption of polycarbonate about 2 tons. In spacecraft, hundreds of different configurations and glass fibre-reinforced polycarbonate components and protective gear for astronauts are used.
A new growth area in the packaging sector is the reusable and re-sterilisable water bottles of various types. As polycarbonate products have the advantages of light weight, impact resistance and good transparency, with hot water and corrosive solutions when washing treatment does not deform and remain transparent, some areas of PC bottles have completely replaced glass bottles. It is predicted that, with the increasing importance attached to the quality of drinking water, the growth rate of polycarbonate usage in this area will remain above 10% and is expected to reach 60,000 tons by 2005.
As polycarbonate has good and constant electrical insulation in a wide range of temperature and humidity, it is an excellent insulating material. At the same time, its good flame-retardant properties and dimensional stability have led to the formation of a wide field of application in the electrical and electronic industry.
Polycarbonate resins are mainly used in the production of various food processing machines, power tool housings, bodies, brackets, refrigerator freezer drawers and vacuum cleaner parts. Polycarbonate materials are also used for important components in computers, video recorders and colour televisions, where high precision is required.
Polycarbonate occupies a very important position in this field due to its unique characteristics of high light transmission, high refractive index, high impact resistance, dimensional stability and easy processing and moulding. Optical lenses made from optical grade polycarbonate are not only used in cameras, microscopes, telescopes and optical test instruments, but also in film projector lenses, photocopier lenses, infrared auto-focus projector lenses, laser beam printer lenses, as well as various prisms, multi-surface mirrors and many other office equipment and home appliances.
Another important application for polycarbonate in optical lenses is as a lens material for children’s eyeglasses, sunglasses and safety glasses and adult eyeglasses. Polycarbonate consumption in the world eyewear industry has been growing at an average annual rate of more than 20%, showing great market dynamism.
Optical disc manufacturing
With the rise of the information industry, optical discs made of optical grade polycarbonate are developing rapidly as a new generation of audio and video information storage media. With its excellent performance characteristics, polycarbonate has become the main raw material for the world’s optical disc manufacturing industry. The amount of polycarbonate consumed by the world’s optical disc manufacturing industry has exceeded 20% of the overall consumption of polycarbonate, with an average annual growth rate of over 10%. According to figures released by the State General Administration of Press and Publication, there were 748 optical disc production lines in China in 2002, with an annual consumption of about 80,000 tonnes of optical grade polycarbonate, all of which were imported. Thus the application prospect of polycarbonate in the field of optical disc manufacturing is extremely broad.
Applications Editor Podcast
Used in the manufacture of large lampshades, protective glass, optical instruments such as the left and right eyepiece barrels, etc. It can also be widely used as a transparent material in aircraft.
Polycarbonate is an excellent E (120℃) grade insulating material, used for manufacturing insulating connectors, coil frames, tube holders, insulating sleeves, telephone housings and parts, battery cases for mining lamps, etc. It can also be used to make parts with high dimensional accuracy, such as compact discs, telephones, electronic computers, video recorders, telephone exchanges, signal relays and other communication equipment. Polycarbonate films are also widely used as capacitors, insulating skins, audio tapes, colour video tapes, etc.
Machinery and equipment
It is used to manufacture various gears, racks, worm gears, worm gears, bearings, cams, bolts, levers, crankshafts, ratchets, as well as parts of mechanical equipment such as housings, covers and frames.
Cups, tubes, bottles, dental instruments, drug containers and surgical instruments for medical use, even artificial kidneys, artificial lungs and other artificial organs.
In construction, it is used as double-walled panels with hollow bars and heated glass; in the textile industry, it is used as textile yarn tubes and textile machine tiles; in daily use, it is used as milk bottles, tableware, toys, models, LED lamp housings and mobile phone housings.
Modified uses edit Podcast
The purpose of modified PC is to toughen, improve molding and processing properties, reduce residual deformation, increase flame retardancy, etc. Specific varieties of PC that can be modified are
PC/ABS can improve the bending modulus, heat resistance, plating performance, etc.
PC/PET, PBT can improve the chemical resistance, solvent resistance, etc.
PC/PMMA can be added to organic glass to improve the appearance of pearlescent colours.
PC/PA, HIPS can improve impact toughness and surface finish.
PC/HDPE can improve boiling water resistance, ageing resistance, weather resistance, while LDPE is less effective.
PC is modified with glass fibre or carbon fibre for reinforcement to improve mechanical strength.
And with bromine flame retardants and antimony trioxide, it can be made into flame retardant grade PC.
Others and polysulfone, aromatic polycarbonate, polyformaldehyde, polypropylene, polystyrene can be blended and modified to achieve a balance between economy and performance.