polycarbonate is an amorphous, tasteless, odorless, non-toxic transparent thermoplastic polymer, with excellent mechanical, thermal and electrical properties, especially impact resistance, good toughness, small creep, product size stability. Its notched impact strength reaches 44kj/mz, and its tensile strength is> 60MPa. Polycarbonate has good heat resistance and can be used for a long time at -60~120 ℃, with heat distortion temperature of 130~140 ℃, glass transition temperature of 145~150 ℃, no obvious melting point, and melting state at 220~230 ℃. Thermal decomposition temperature> 310 ℃. Due to the rigidity of the molecular chain, its melt viscosity is much higher than that of general thermoplastics. Polycarbonate has excellent electrical properties. Its volume resistivity and dielectric constant are equivalent to those of polyester film, which are 5 × 1013 Q.m and 2.9(106Hz), respectively. Dielectric loss tangent (106Hz)<1.0 × 10 -2, second only to polyethylene and polystyrene. It is almost unaffected by temperature and is close to constant in the range of 10~130 ℃. It is suitable for making electronic components working at higher temperatures. Polycarbonate light transmission, light transmittance of 85% to 90%. In terms of chemical resistance, it is stable to dilute acids, oxidants, reducing agents, salts, oils, and aliphatic hydrocarbons, but it is not resistant to alkali, amines, ketones, aromatic hydrocarbons and other media, and is easily soluble in chlorinated hydrocarbons such as dichloromethane and dichloroethane. Products are prone to stress cracking, especially long-term immersion in boiling water is easy to cause hydrolysis and cracking. In addition, polycarbonate has a low water absorption rate of 0. 16%; Excellent weather resistance; Good coloring; Flammability conforms to UL specifications 94 Vl and 94 V-2, and is a self-extinguishing resin.

Industrial production has two methods.

1. the transesterification method, bisphenol A, diphenyl carbonate (the ratio of substances is 1:1. 05) and catalyst (such as sodium tetraphenylboron) are added into the transesterification kettle, and the transesterification reaction is carried out at 165-250 ℃ under the pressure of 6. 67 ~ 1.33kPa. When the by-product of the reaction, phenol, is distilled to 80% ~ 90% of the theory, the material is transferred to a polycondensation kettle and then polycondensation reaction is carried out at 250~300 ℃ and the residual pressure is less than 0.133kPa. when the molecular weight of the reactant is increased to the required value, the material is released and the product is obtained by cutting. Transesterification generally produces low and medium viscosity resins.
2. phosgenation method (interfacial polycondensation method) according to the specified ratio, bisphenol A, sodium hydroxide aqueous solution catalyst, molecular weight regulator, antioxidant and solvent (halogenated alkanes or halogenated aromatic hydrocarbons), phosgene in 20~40 ℃ temperature and atmospheric pressure for interfacial polycondensation reaction. After the reaction reaches the end point, the upper alkali salt solution is removed to produce polycarbonate glue. The glue solution is washed with high efficiency (alkali washing, acid washing and water washing) to remove residual bisphenol A, catalyst, inorganic salts and mechanical impurities, and then polycarbonate is precipitated in powder form by precipitating agent (acetone or xylene, etc.) or spray vaporization. The dried powder resin is added with stabilizers, etc., and the product is obtained by extrusion granulation, and the phosgene method can produce high molecular weight or adjustable molecular weight, higher quality products.

in the electronic and electrical industry can be used as electronic computers, televisions, radios, speakers and household appliances, such as insulation connectors, coil frames, terminals, gaskets and so on. It can also be used as an electrical tool shell such as hand drill shell, telecommunications equipment cover body, etc. In the mechanical industry, it is suitable to transmit small and medium load parts such as gears, racks, cams, worms, etc. Used as a force is not large fasteners such as screws, nuts, etc. to replace metal parts. In terms of safety and medical treatment, it can be used as safety helmet, aerospace cap, explosion-proof glass, protective glasses, and medical surgical utensils that can be sterilized at high temperature. In aviation, transportation and optical machinery can be used as aircraft, trains, cars, ships windshield glass, seat window cover, lampshade, sunglass glass, CD, camera optical mechanical parts, etc. In construction and agriculture, it is widely used as high impact strength window glass and glass greenhouse, with high safety and decoration. In the textile industry, it can make all kinds of weft tube, yarn tube, wool spinning tube, hemp spinning tube, etc. In addition, polycarbonate can also be used as a foam structural material.

The raw materials for the production of resin have different degrees of irritation to the skin and mucous membranes of the human body, which can cause skin allergic reactions and inflammation; at the same time, pay attention to the harm of resin dust to the human body. Long-term inhalation of high-concentration resin dust can cause lung lesions. Most of the resin has the same risk characteristics: the case of open flame, high temperature flammable, and oxidant contact caused by the risk of combustion, therefore, the operator to improve the operating environment, the operating area and non-operating area consciously cut off, as far as possible automation, sealing, installation of ventilation facilities. This product is externally used in plastic woven bags such as polypropylene, lined with plastic bags (such as polyethylene bags), 25kg per bag. During storage and transportation, prevent heat and moisture, avoid organic solvents and alkaline items erosion, not long-term exposure to outdoor.

can be processed by extrusion, injection molding, blow molding and vacuum forming methods to manufacture various tubes, plates, containers, products and films, among which the most commonly used is injection molding. Because in the process of 300 ℃, trace moisture will cause hydrolysis of polycarbonate and reduce the performance, so the material must be strictly dried before processing, so that the moisture content of the resin is controlled below 0. 03%. Generally, it is continuously dried in a 110 ℃ blast oven for 10~12h; if the vacuum oven is used, it can be reduced to 6~8h. The thickness of the material layer shall not exceed 20mm. In the injection molding, the screw type injection molding machine is more uniform than the plunger type injection molding machine, the processing temperature is slightly lower, and the thermal degradation phenomenon is less. Generally, higher barrel temperature and higher injection pressure are used, and the method of increasing mold temperature is used to reduce the internal stress generated during the molding process. Generally, the temperature range of the barrel is 220~250 ℃ in the rear section, 230~270 ℃ in the middle section, and 240~290 ℃ in the front section. The injection pressure is 39.2~127. 5MPa. The mold temperature is controlled at 80~120 ℃. When processing the insert, the metal insert needs to be heated to above 120 ℃, and the insert with a diameter of 1~2mm does not need to be heated. The thickness of the polycarbonate covering the insert shall be equal to the diameter of the insert for the iron insert; 0.9 times the diameter of the brass; the aluminum part shall be 0.8 times. The injection molding cycle depends on the thickness of the product, from tens of seconds to several minutes. Most of the polycarbonate injection molded products have internal stress. Therefore, the products need to be heat treated in an oil bath at 110 N130 ℃, a hot air oven or an infrared incubator. The processing time depends on the thickness of the products.