PET is divided into fiber grade polyester chips and non-fiber grade polyester chips. Fiber-grade polyester is used to make polyester staple fibers and polyester filaments, and it is the raw material for processing fibers and related products in polyester fiber enterprises. Polyester is the largest variety of chemical fiber. Non-fiber polyester is also used in bottles, films and other fields, and is widely used in packaging industry, electronic appliances, medical care, construction, automobiles and other fields. Packaging is the largest non-fiber application market of polyester and the fastest developing field of PET.
1 and pte overview:
The full name of PET is polyethylene terephthalate, abbreviated as PET or PEIT (hereinafter referred to as PET), commonly known as polyester resin, but polyethylene terephthalate is the most important variety of thermoplastic polyester. The molecular weight of the repeating unit is192g/mol. It is a polycondensate of terephthalic acid and ethylene glycol. Together with PBT, it is called thermoplastic polyester or saturated polyester. 1946, the first patent for preparing PET was published in Britain, 1949, and the pilot test of ICI formula in Britain was completed. However, after purchasing the patent, DuPont Company of the United States set up a production device at 1953, which took the lead in realizing industrial production in the world. In the early days, PET was almost entirely used in synthetic fibers (commonly known as polyester and polyester in China). Since 1980s, PET has made a breakthrough as an engineering plastic, and has successively developed nucleating agents and crystallization promoters. As thermoplastic polyesters, PET and PBT have become one of the five major engineering plastics.
2. Advantages of 2.PET as a packaging material:
① Good mechanical properties, impact strength 3~5 times that of other films, and good folding resistance.
② Oil resistance, grease resistance, dilute acid resistance, dilute alkali resistance and resistance to most solvents.
③ It has excellent high and low temperature resistance, can be used for a long time in the temperature range of 120℃, and can be used for a short time in the temperature range of 150℃ and -70℃, which has little effect on its mechanical properties.
④ The permeability of gas and water vapor is low, and it has excellent gas, water, oil and odor resistance.
⑤ High transparency, blocking ultraviolet rays and good gloss.
6. Non-toxic, tasteless, hygienic and safe, and can be directly used for food packaging.
3. The characteristics of 3.pte:
PET is a kind of high crystalline polymer with milky white or light yellow, and its surface is smooth and shiny. It has good creep resistance, fatigue resistance, wear resistance and dimensional stability, low wear and high hardness, and has the greatest toughness among thermoplastics: good electrical insulation, little influence by temperature, but poor corona resistance. Non-toxic, weatherproof, good chemical stability, low water absorption, weak acid and organic solvent resistance, but not hot water immersion and alkali resistance. PET resin has high glass transition temperature, slow crystallization speed, long molding cycle, large molding shrinkage, poor dimensional stability, brittle crystallization and low heat resistance.
4. In addition to the characteristics of PBT, PET has the following characteristics:
① Thermal deformation temperature and long-term service temperature are the highest among thermoplastic general engineering plastics.
② The bending strength is 200MPa, the elastic modulus is 4000MPa, the creep resistance and fatigue resistance are also very good, the surface hardness is high, and the mechanical properties are similar to those of thermosetting plastics.
③ Because the price of ethylene glycol used in the production of PET is almost half of that of butanediol used in the production of PBT, PET resin and reinforced PET are the lowest in engineering plastics with high cost performance.