Generally, PET bottle blank is molded by hot runner mold. Generally, the proportion of PET preform recycled materials should not exceed 25%, and the recycled materials should be thoroughly dried.ĭue to the short stable time of PET after the melting point and the high melting point, it is necessary to use an injection system with more temperature control sections and less self-friction heat generation during plasticization, and the actual weight of the product (water-containing material) should not be less than machine injection. The complete dryness of the material can be checked by air shot method. Therefore, before processing, the material must be dried, and the drying temperature is 150☌ for more than 4 hours generally 170☌ for 3-4 hours. When the moisture content exceeds the limit, the molecular weight of PET decreases during processing, and the product becomes colored and brittle. Since PET macromolecules contain lipid groups and have a certain degree of hydrophilicity, pellets are sensitive to water at high temperatures. (Essentially caused by oxidative degradation of PET) Increase of AA (Acetaldehyde) acetaldehyde The ideal moisture content after drying is about: 0.001-0.004% (The essence is caused by the hydrolytic degradation of PET)Īt the same time, make high temperature preparations for PET entering the injection molding machine for shear plasticization It affects the pressure resistance of the bottle and is easy to break. IV (Intrinsic Viscosity) viscosity drop. Odorous effect on bottles, resulting in off-flavors (but little effect on humans) Increase of AA (Acetaldehyde) acetaldehyde. High levels of moisture will exacerbate during production: The transparency is as high as more than 90%, the surface gloss is excellent, and the appearance is glassy the aroma retention is excellent, the air tightness is good the chemical resistance is excellent, and almost all organic drugs are resistant to acids the sanitation is good it will not burn Toxic gas is generated the strength characteristics are excellent, and various characteristics can be further improved by biaxial stretching.īecause PET has a certain degree of water absorption, it will absorb a lot of water during transportation, storage and use. Under a certain temperature and pressure, the mold is filled with raw materials, and under the processing of the injection molding machine, it is processed into a preform with a certain thickness and height corresponding to the mold. PET preforms are reprocessed by blow molding to form plastic bottles, including bottles for cosmetics, medicine, health care, beverages, mineral water, reagents, etc. A method of forming PET plastic bottles through blow molding.
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