Product Details

CasNo： 25037-45-0

MF： (C15H16O2.CH2O3)x

Appearance： powder

Delivery Time： 15 days

Packing： 25kg/bag

Purity： 99%

1. Definition and General Information

Polycarbonate (PC for short) is a type of high - performance thermoplastic polymer. Its molecular chain contains carbonate groups (-O-(C=O)-O-), which endow it with unique properties. The chemical formula can be expressed as \((C_{16}H_{14}O_3)_n\), and its molecular weight generally ranges from 2000 to 7000. It was first developed in the 1950s, with significant contributions from Dr. H. Schnell of Bayer AG in Germany and D. W. Fox of General Electric Company in the USA. Since then, it has become one of the most important engineering plastics in the world.

2. Physical and Chemical Properties

2.1 Physical Properties

• Appearance: PC is usually a transparent, colorless or slightly yellowish, tough solid in its pure form. It can be processed into various shapes, such as transparent cylindrical or spherical particles for easy handling in manufacturing processes, or solid powder in some cases. It has good coloring properties, allowing it to be colored into a variety of colors according to different needs.

• Density: The density of PC is typically around \(1.18 - 1.22\ g/cm³\), which is relatively lightweight compared to some traditional materials like glass, while still maintaining high strength.

• Optical Properties: It exhibits excellent transparency, with a light transmittance of 87% - 91%, close to that of glass, making it an ideal material for optical applications. The refractive index of PC is about 1.587, which is beneficial for applications such as lenses and optical discs. However, factors like surface roughness and internal stress can affect its transparency. For example, a rough surface may cause light scattering, reducing the overall light transmittance, and internal stress can lead to birefringence, also deteriorating the optical quality.

• Mechanical Properties: PC has a balanced combination of rigidity and toughness. Its tensile strength ranges from 60 - 70 MPa, and the elongation at break is 30% - 130%. The flexural strength can reach 100 - 110 MPa, and the flexural modulus is in the range of 2100 - 2440 MPa. It has high impact resistance, with an impact strength (notched) of 17 - 24 \(KJ/m²\), which means it can withstand significant external impacts without breaking easily. But it also has some limitations, such as being sensitive to notches, having relatively poor wear resistance, and being prone to stress cracking under certain conditions.

• Thermal Properties: PC has a wide service temperature range. It can be used continuously in the temperature range of - 60 °C to 130 °C. The glass transition temperature (\(T_g\)) is as high as 145 - 150 °C, and the softening temperature is around 240 °C, with a heat deflection temperature of 130 - 140 °C. This high heat resistance makes it suitable for applications in high - temperature environments. It also shows good cold resistance, with a brittle temperature of 100 °C, and still retains some toughness even at - 180 °C. PC is an amorphous polymer without a distinct melting point. It starts to melt above 220 - 230 °C, and the melt viscosity is relatively high due to the rigidity of its molecular chain. Its thermal conductivity is relatively low, about \(0.19\ W/m·K\), and the coefficient of linear thermal expansion is \((5 - 7)\times10^{-5}\ K^{-1}\), which helps to maintain dimensional stability under temperature changes.

• Electrical Properties: PC has excellent electrical insulation properties. It can maintain good electrical insulation and corona resistance over a wide temperature and humidity range. The dielectric constant and dielectric loss are relatively stable in the temperature range of 10 - 130 °C. For example, at 20 °C, the volume resistivity is \(4.0\times10^{16}\ \Omega·cm\), the dielectric strength is 20 - 22 \(Kv/mm\), the dielectric constant at 50 Hz and 1000 Hz is about 3.1, and the dielectric loss tangent is \((6 - 7)\times10^{-4}\) at 50 Hz.

2.2 Chemical Properties

• Chemical Resistance: PC is resistant to diluted acids, aliphatic hydrocarbons, and alcohols. However, it is sensitive to diluted alkalis, aromatic, and halogenated hydrocarbons. For example, it can be attacked and dissolved by some strong alkaline solutions or certain organic solvents like benzene and chloroform. Manufacturers usually recommend using non - corrosive cleaning agents to clean PC products to avoid affecting their chemical structure and performance.

• Hydrolysis Sensitivity: The ester groups in the PC molecular chain are relatively weak and prone to hydrolysis in the presence of water, especially under high - temperature and high - humidity conditions. Hydrolysis can lead to a decrease in molecular weight, resulting in a decline in mechanical and electrical properties. Therefore, when using PC in applications where it may be exposed to water vapor or high humidity for a long time, appropriate precautions need to be taken, such as using hydrolysis - resistant grades or adding protective coatings.

• Thermal Stability: PC has good thermal stability below 320 °C, with little degradation. But at 330 - 340 °C, oxygen - containing degradation and thermal degradation may occur, and the initial decomposition temperature is about 350 °C, with the main chain breaking at around 470 °C. When burning, PC burns slowly with a yellow flame, melts and foams, and emits a special foul smell of flowers and fruits, and it will gradually extinguish after leaving the fire source.

3. Production Process

The most common production methods of PC are the melt transesterification method and the phosgene method.

• Melt Transesterification Method: In this process, bisphenol A and diphenyl carbonate are used as raw materials. They react through transesterification and polycondensation reactions. First, bisphenol A and diphenyl carbonate are mixed and heated in the presence of a catalyst. The transesterification reaction occurs between them, gradually forming oligomers. Then, under high temperature and reduced pressure conditions, the oligomers further undergo polycondensation to form high - molecular - weight PC. This method has the advantages of being environmentally friendly as it does not use phosgene (a highly toxic gas), and the process is relatively simple. However, it requires strict control of reaction conditions, such as temperature, pressure, and the ratio of raw materials, to ensure the quality of the product.

• Phosgene Method: Bisphenol A reacts with phosgene (\(COCl_2\)) in this method. Bisphenol A is dissolved in an organic solvent, and phosgene is introduced into the reaction system. Under the action of a catalyst and appropriate reaction conditions, a polymerization reaction occurs to form PC. Although this method can produce high - quality PC, the use of phosgene brings potential environmental and safety risks, so strict safety measures are required in the production process.

In addition to the raw materials and the main reaction, various catalysts and additives are often added during the production of PC to improve its performance. For example, antioxidants can be added to prevent oxidation and degradation during processing and use, and heat - stabilizers can enhance its thermal stability.

4. Product Types

• General - Purpose PC: This type is suitable for a wide range of applications with common requirements, such as general - purpose plastic products, some electronic component housings, and simple mechanical parts. It has basic mechanical, thermal, and optical properties to meet the needs of general - use scenarios.

• High - Purity PC: With a purity of over 99%, it is mainly used in applications with strict requirements for purity, such as the medical field (for manufacturing medical devices that come into direct contact with the human body, like syringe barrels and medical instrument components) and the optical disk manufacturing industry (to ensure high - quality data storage and reading).

• Reinforced PC: By adding reinforcing materials such as glass fibers, carbon fibers, or mineral fillers, the mechanical properties of PC can be significantly improved. Glass - fiber - reinforced PC, for example, has higher tensile strength, flexural strength, and modulus, and better dimensional stability. It is often used in the automotive industry for manufacturing parts that require high strength and heat resistance, such as engine covers, intake manifolds, and some structural components.

• Flame - Retardant PC: Flame - retardant additives are incorporated into PC to enhance its fire - resistance properties. These additives can inhibit the combustion process of PC, making it self - extinguish when leaving the fire source. Flame - retardant PC is widely used in the electronics and electrical industry, such as in the production of electrical enclosures, circuit boards, and connectors, where fire safety is of great concern.

• Antistatic PC: Special antistatic agents are added to PC to reduce its surface resistivity and prevent the accumulation of static electricity. This type of PC is suitable for applications in the electronics industry, especially in the manufacturing of electronic components and devices that are sensitive to static electricity, such as semiconductor packaging materials and electrostatic - sensitive equipment housings.

5. Applications

• Electronics and Electrical Appliances:

• • Insulating Materials: PC is an excellent E - grade (120 °C) insulating material. It is used to make components such as connectors, sockets, plugs, and insulating sleeves in electrical and electronic devices, ensuring reliable electrical insulation and preventing electrical leakage.

• • Housings and Covers: The high impact resistance and good dimensional stability of PC make it suitable for manufacturing the housings of electronic products such as computers, tablets, and mobile phones. It can protect the internal components from external impacts and maintain the integrity of the product.

• • Optical Components: In the field of optical storage, PC is the main material for manufacturing CDs, DVDs, and Blu - ray discs due to its high transparency and good optical properties. It can accurately record and read optical information.

• Automotive Industry:

• • Exterior Parts: PC is used to make automotive lighting components such as headlamp lenses and taillight covers. Its high transparency, impact resistance, and heat resistance ensure good lighting performance and long - term durability. It is also used in the production of automotive bumpers, either alone or in the form of PC - based composites, providing good shock - absorption and energy - dissipation capabilities.

• • Interior Parts: PC can be used to manufacture dashboard components, interior trim panels, and door handles. Its excellent aesthetic properties and mechanical strength can meet the requirements of automotive interior design and daily use.

• Construction and Architecture:

• • Glazing Materials: PC sheets, such as polycarbonate hollow sunlight panels and solid sheets, are widely used in construction. They have high light transmittance, can effectively transmit natural light, and at the same time, provide good insulation performance, reducing heat transfer and energy consumption. They are suitable for applications such as skylights, curtain walls, and greenhouse covers.

• • Safety Barriers: PC - based products are used to make safety barriers in public places, such as in banks, embassies, and detention centers. Their high strength and impact resistance can provide reliable protection.

• Medical Field:

• • Medical Devices: PC can be used to manufacture a variety of medical devices. For example, it is used to make medical instrument housings, infusion sets, and blood collection tubes. Some PC grades are biocompatible and can be used to make components that come into direct contact with the human body, such as artificial organs (e.g., parts of artificial kidneys and artificial lungs) and surgical instruments.

• • Packaging: PC is also used for medical packaging, such as packaging for drugs and medical supplies. Its transparency allows for easy inspection of the contents, and its chemical resistance can protect the packaged items from external chemical damage.

• Optical and Lighting:

• • Lenses: PC is used to make various optical lenses, including spectacle lenses (both for children and adults), camera lenses, and microscope lenses. Its high refractive index and good optical clarity can provide excellent optical performance.

• • Lighting Fixtures: It is used in the production of large - scale lighting fixtures, such as lamp shades and light diffusers. PC can effectively distribute and soften light, improving the lighting quality.

6. Packaging and Storage

• Packaging:

• • For Granular Products: Granular PC is usually packed in multi - layer composite bags. The inner layer is a food - grade PE film to prevent leakage and moisture penetration, and the outer layer is a kraft paper or woven bag to enhance the load - bearing capacity. Generally, each bag has a net weight of 25 kg. For large - volume transportation, 500 - kg or 1000 - kg big - bag packaging can also be used.

• • For Sheet and Plate Products: PC sheets and plates are first covered with a PE protective film on the surface to prevent scratches. Then, multiple sheets are stacked and fixed on wooden or plastic pallets with packing straps, and the outer layer is wrapped with stretch film to prevent moisture and dust. The size of the pallet is usually 1.2 m × 1.0 m, which can be customized according to the size of the sheets. For some high - value or thick - walled products, wooden boxes may be used for packaging, with cushioning materials such as EPE foam or foam inserted inside to protect against impact during transportation.

• Storage: PC should be stored in a dry, ventilated warehouse away from direct sunlight. The storage temperature is preferably maintained between 5 - 30 °C. High humidity environments should be avoided to prevent hydrolysis of PC. When stored for a long time, it is necessary to regularly check the condition of the product to ensure its quality remains unchanged.

7. Quality Assurance and Certification

Reputable manufacturers of PC products often implement strict quality control systems. They conduct regular inspections of raw materials, closely monitor the production process, and perform comprehensive quality testing on finished products. Quality tests may include physical property tests (such as density, tensile strength, and optical properties), chemical property tests (such as chemical resistance and hydrolysis resistance), and performance - based tests in relevant application scenarios.

Many PC products also comply with international and industry - specific certifications. For example, in the medical field, products may need to meet relevant medical device regulations and certifications such as ISO 13485 (Quality Management Systems for Medical Devices) and specific regulatory approvals in different countries (e.g., FDA approval in the United States). In the food - contact application, PC products need to comply with food - safety - related regulations and certifications, such as FDA regulations in the United States and EU 10/2011 in the European Union, ensuring that no harmful substances are released when in contact with food. In the electronics industry, products may need to meet electrical safety and environmental protection certifications such as RoHS (Restriction of Hazardous Substances) and UL (Underwriters Laboratories) certifications.