Application of pet in various industries
PET plastic is the abbreviation of polyethylene terephthalate, abbreviated as pet or PETP. Polyethylene terephthalate plastics mainly include polyethylene terephthalate pet and polybutylene terephthalate PBT. Polyethylene terephthalate is also commonly known as polyester resin, commonly known as polyester resin.
PET plastic structure
The molecular structure of PET plastic is highly symmetrical and has certain crystallization orientation ability, so it has high film-forming and. Pet plastics have good optical properties and weather resistance, and amorphous pet plastics have good optical transparency. In addition, pet plastic has excellent wear resistance, friction, dimensional stability and electrical insulation. PET bottles are widely used because of their high strength, good transparency, non-toxic, anti permeability, light weight and high production efficiency. The molecular chain structure of PBT is similar to that of pet, and most of the properties are the same, but the main chain of PBT is changed from two methylene chains to four, so the molecules are more flexible and the processing performance is better.
Pet is a milky white or light yellow highly crystalline polymer with smooth and shiny surface. Good creep resistance, fatigue resistance, friction resistance and dimensional stability, low wear and high hardness, with large toughness in thermoplastic; Good electrical insulation performance, little affected by temperature, but poor corona resistance. Non toxic, weather resistant, chemical resistant, good stability, low water absorption, resistant to weak acids and organic solvents, but not resistant to hot water immersion and alkali. PET resin has high glass transition temperature, slow crystallization speed, long molding cycle, long molding cycle, large molding shrinkage, poor dimensional stability, brittle crystallization and low heat resistance.
Through the improvement of nucleating agent, crystallizer and glass fiber reinforcement, pet not only has the properties of PBT, but also has the following characteristics:
1. The thermal deformation temperature and long-term service temperature are higher than those of thermoplastic general engineering plastics
2. Because of its high heat resistance, the Reinforced PET is immersed in a soldering bath at 250 ℃ for 10s, which hardly deforms and does not change color. It is especially suitable for preparing electronic and electrical parts for soldering
3. The bending strength is 200MPa, the elastic modulus is up to 4000mpa, the creep and fatigue resistance is also very good, the surface hardness is high, and the mechanical properties are similar to those of thermosetting plastics
4. Since the price of ethylene glycol used in PET production is almost half lower than that of butanediol used in PBT production, PET resin and Reinforced PET are the lowest in engineering plastics and have high cost performance
China's pet production scale lags far behind several major foreign manufacturers. In the 1980s, China has gradually introduced 10000 ~ hundreds of thousands of tons of advanced pet resin synthesis units from abroad, and great progress has been made in quality and output. According to the statistics of China Textile society, in 1997, China produced 1.74 million tons of PET chip resin, of which the production capacity of chip resin for high viscosity packaging was 224000 tons, so there are sufficient sources of PET engineering plastic grade resin. As the devices for preparing various blending modified PET plastics are common with those for blending modification of other polymers, and the manufacturing of domestic blending extruders has also formed a certain scale, once the market is developed, the production of domestic pet plastics will also grow rapidlyglass fiber reinforced pet is suitable for electronic, electrical and automotive industries. It is used for various coil frames, transformers, televisions, recorder parts and housings, automotive lamp holders, lampshades, white heat lamp holders, relays, selenium rectifiers, etc. At present, the consumption proportion of PET engineering plastics in several application fields is: Electrical and electronic 26%, automobile 22%, machinery 19%, appliances 10%, consumer goods 10%, and others 13%. At present, the total consumption of PET engineering plastics is still small, accounting for only 1.6% of the total pet
1. Film and sheet: all kinds of food, medicine, non-toxic and sterile packaging materials; High grade packaging materials for textiles, precision instruments and electrical components; Base materials of audio tape, video tape, film, computer floppy disk, metal coating and photosensitive film; Electrical insulating materials, capacitor films, flexible printed circuit boards, film switches and other electronic and mechanical fields
2. Application of packaging bottle: its application has developed from carbonated beverage at the beginning of * to beer bottle, edible oil bottle, condiment bottle, medicine bottle, cosmetics bottle, etc
3. Electronic and electrical appliances: manufacturing connectors, coil winding tubes, integrated circuit enclosures, capacitor enclosures, transformer enclosures, TV accessories, tuners, switches, timer enclosures, automatic fuses, motor brackets and relays, etc
4. Auto parts: such as distribution panel cover, ignition coil, various valves, exhaust parts, distributor cover, measuring instrument cover, small motor cover, etc. it can also make use of the excellent coating, surface gloss and rigidity of pet to manufacture auto external parts
5. Mechanical equipment: manufacturing gear, cam, pump shell, pulley, motor frame and clock parts. It can also be used as microwave oven, baking pan, various ceilings, outdoor billboards and models
6. The molding processing of pet plastics can be injection molding, extrusion, blow molding, coating, bonding, machining, electroplating, electroplating, vacuum metal plating and printing.
