PET Plastic Bottle When Injection Precautions
PET plastic bottle is one of the types of packaging bottles often used in cosmetics. The cost of the bottle of this material is not too high, so PET plastic bottle for so many cosmetics container materials, cost-effective is still very high, and has been favored by many cosmetics brand customers in the market. What should we pay attention to when molding such a popular bottle?
Because PET macromolecules contain lipid groups, with certain hydrophilicity, the grain is sensitive to water at high temperature. When the moisture content exceeds the limit, the molecular weight of PET is reduced in processing, and the finished product is colored and brittle. Trapped in this, it is necessary to dry the material before processing, its dry temperature is 150℃, more than 4 hours, generally 170℃, 3-4 hours. Air - fire method can be used to check whether the data is completely boring. Take back material share generally do not exceed 25%, and to take back material completely boring.
Because PET has a short stable time after melting point and a high melting point, it is necessary to choose an injection system with more temperature control sections and less heat generated by self-conflict during plasticization. Moreover, the practical component of the finished product (water mouth material) of the cosmetic packaging bottle manufacturer should not be less than 2/3 of the machine injection amount.
PET plastic bottle embryo is generally molded with warm flow mold, and there should be a heat insulation board between the mold and the injection molding machine template, the thickness of which is about 12mm, and the heat insulation board must be able to accept high pressure. The exhaust is necessary enough to prevent partial overheating or fragmentation, but the depth of the exhaust port is generally not more than 0.03mm, otherwise it simply occurs flying edge. The injection rate should be fast to prevent premature solidification during injection. However, too fast and high shear rates make the material brittle, usually within 4 seconds.
