Main Applications of Polycarbonate_Industrial Additives

Main application background and overview of polycarbonate

A type of linear polymer containing repeating carbonate groups in the sub-chain. R in the structural formula can be an aliphatic, alicyclic or aromatic group. Research on aliphatic and aromatic polycarbonates has a history of 50 and 100 years respectively. Industrial production includes the phosgene method and the transesterification method. Both have their own advantages, but the phosgene method is the main method, and its output accounts for more than 90% of calcium carbonate. Generally speaking, polycarbonate often refers to a bisphenol A-type polycarbonate, which began industrial production in 1960. Polycarbonate is one of the most important engineering plastics. It has excellent properties such as toughness and stiffness, dimensional stability, easy coloring, transparency, good electrical insulation, corona resistance, and stability to ozone. It can withstand turning, milling, planing, Mechanical processing such as grinding, sawing, drilling, and stamping is widely used in various sectors of the national economy to replace non-ferrous metals such as copper, aluminum, and zinc and non-metallic materials such as glass and wood to manufacture windshields and driving windows for aircraft and vehicles. Used as glass for transportation and housing, making lighting fixtures, explosion-proof lighting fixtures and safety masks, etc. Used to manufacture various mechanical parts (such as gears, screws, crankshafts, guide rails, valves, pipe fittings, etc.), plastic optical fibers, communication equipment and various types of eyeglass lenses. It can also be used to manufacture housings and parts for various electrical equipment and appliances. Because it is non-toxic, tasteless and heat-resistant, it can be used to make various medical appliances, surgical instruments, dental implant materials, kitchen utensils, beverage containers, food utensils, water filters, etc. Polycarbonate films can be used to make capacitors, audio tapes, color video tapes, solar energy utilization devices, microwave heating systems, reverse dialysis membranes, and ultrafiltration membranes; its foam plastics are flame-resistant and insulating and are used in the construction industry. However, polycarbonate has low fatigue strength and is prone to stress cracking. Glass fiber reinforcement is commonly used to avoid the above shortcomings and improve many other properties. If blended with a variety of polymers, or added with various stabilizers, flame retardants, and antistatic agents, new varieties can be produced to expand its application scope. .

Main application structures of polycarbonate

Main application properties of polycarbonate

1. Optical properties. Its light transmittance is about 90%, which is close to glass but lighter than glass, not fragile, and easy to process. Some people may think that this is the so-called “plexiglass”, but it is not! The scientific name of what we call plexiglass is “polymethyl methacrylate”. Although plexiglass is also a transparent material and even has better optical properties than polycarbonate, its mechanical properties and heat resistance are much different than polycarbonate, and it is not fireproof. Therefore, in terms of comprehensive performance, polycarbonate is more comprehensive and has a wider range of applications.

2. Mechanical properties. Polycarbonate is an organic combination of rigidity and toughness. Generally speaking, if a material is very rigid, it will be very brittle and will break if dropped to the ground. However, although polycarbonate has very good rigidity and is difficult to bend, its toughness is also quite good. Products made of it are not easily broken even if heavy objects fall on it from a high place. For example, if a 4-kilogram ball falls from a height of 0.1 meters onto a 1.2cm-thick polycarbonate plate, the polycarbonate plate will remain intact.

3. Flame retardant properties. In November 2010, a fire broke out on Jiaozhou Road in Shanghai, which attracted people’s attention to fire-resistant and flame-retardant materials. Compared with other plastics, polycarbonate has excellent fire resistance. Pure polycarbonate can pass a certain level of fire testing without adding any flame retardants. If supplemented with a small amount of flame retardants, polycarbonate can reach the highest level of fire protection standards without losing its excellent optical and mechanical properties, which is something other plastic products simply cannot do. High temperature resistance. As the temperature rises, all plastics will soften at a certain temperature and lose their use value. This temperature value is the maximum use temperature of the plastic. It is conceivable that the higher the temperature value, the wider the use range of plastics. The maximum use temperature of polycarbonate can reach 120 degrees to 130 degrees. About a dozen years ago, the so-called “space cup” became popular, which was transparent and lightweight. It was made of polycarbonate.

In addition to the four main characteristics mentioned above, polycarbonate also has some other excellent properties, such as electrical properties, dimensional stability, etc.

Main application preparation of polycarbonate

At present, there are two main production methods of polycarbonate: interfacial polycondensation process and melt polymerization process.

1) Interfacial polycondensation process (also known as phosgene method): First industrialized by GE and Bayer in 1958. In the following decades, other large companies such as Japan’s Asahi Kasei, Teijin, Mitsubishi, and the United States’ Dow also built industrialized devices. The advantages of the interfacial polycondensation process are mature technology, high product quality, easy large-scale and continuous production, and good economy. Therefore, it has long dominated PC production (about 90% of the world’s PC production currently uses this method), and some new The device still uses this process. But in the long term, phosgene and methylene chloride pose safety and health risks, prompting the development of safer and more environmentally friendly polycarbonate synthesis processes. That is, non-phosgene process.

2) Melt polymerization process (also known as non-phosgene method): melt polycondensation of diphenyl carbonate and bisphenol A (BPA). This method does not require washing and drying processes, and the operation is simpler than the interface process.Qualitative, it has formed a broad application field in the electronic and electrical industry. Polycarbonate resin is mainly used in the production of various food processing machinery, power tool casings, bodies, brackets, refrigerator freezer drawers and vacuum cleaner parts. In addition, polycarbonate materials have also shown extremely high use value in areas such as computers, video recorders, and important components in color televisions that require high precision parts.

7. Optical lens

Polycarbonate occupies an extremely important position in the field of optical lenses due to its unique characteristics of high light transmittance, high refractive index, high impact resistance, dimensional stability and easy processing and molding. Optical lenses made of optical grade polycarbonate can not only be used to make cameras, microscopes, telescopes and optical testing instruments, but also can be used to make movie projector lenses, copier lenses, infrared auto-focus projector lenses, laser beam printer lenses, As well as various prisms, polygonal reflectors, etc., its application market is extremely broad. Another important application area of ​​polycarbonate in optical lenses is as a lens material for children’s glasses, sunglasses, safety glasses and adult glasses. In recent years, the average annual growth rate of polycarbonate consumption in the world’s eyewear industry has remained above 20%, showing great market vitality.

8. CD basic materials

Compact discs, as audio and video information storage media, are another large market for polycarbonate applications. However, in recent years, due to the influence of emerging media such as the Internet, tablet computers, and smartphones, the global optical disc market demand has shrunk sharply. The global copy volume of CD discs will drop to 17% in 2009, and the volume of DVD sodium carbonate discs may drop to 36% in 2009, the output growth of Blu-ray discs is also gradually slowing down. In the absence of new technological breakthroughs and the emergence of new consumer markets, the market demand for optical disc replication will continue to shrink year by year.

9. LED lighting industry

In recent years, facing the global energy crisis, the LED industry has mushroomed and is now widely used in lighting, display, backlight and other industries. The application of LED lighting will gradually phase out incandescent lamps and fluorescent lamps, which is of great significance to achieving energy conservation and emission reduction and actively responding to global climate change. In 2013, the global LED lighting market size was approximately US$27 billion, while China’s market size in 2013 was also approximately RMB 48 billion. Because polycarbonate is lightweight, easy to process, has high toughness, and has flame-retardant and heat-resistant properties, it has become the first choice to replace glass materials in LED lighting. Overall, the global electronic products market, especially the consumer electronics market, accounts for about 20% of the polycarbonate terminal market share; the sheet and film market, mainly used in the construction industry, accounts for 18% of the polycarbonate terminal market share. %; the optical media market accounts for 18%; the electrical appliances and automotive non-window markets each account for 12%. The application situation in each region is different: for example, in 2012, in the United States, the automotive industry accounted for about 1/4 of the demand for polycarbonate, making it the largest application market, followed by the construction industry. In Western Europe, the construction industry accounts for about a quarter of polycarbonate resin demand, followed by the automotive industry. The situation in China is different. Although China’s automobile industry consumed more polycarbonate than the United States and Europe combined in 2012, it only accounted for 10% of China’s total consumption, which is equivalent to home appliances, household products and optical disc applications. In my country, the largest consumer area of ​​polycarbonate is the electronics and electrical industry, accounting for about 1/3 of the total demand.