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Precautions for the production of pet plastic bottles
by：Lisson
2021-04-07
Information summary
etPlastic bottles have better rheology in the molten state, and the pressure has a greater effect on viscosity than temperature. Therefore, the pressure is mainly used to change the mobility of the melt. Plastic bottles have different usage conditions in different environments...
The rheology of pet plastic bottles in the molten state is better, and the influence of pressure on viscosity is greater than that of temperature. Therefore, pressure is mainly used to change the mobility of the melt. Plastic bottles have different usage conditions in different environments, so the rheology and viscosity of the plastic bottles are effectively controlled in the molten state.
, processing of raw materials. Because pet plastic bottle macromolecule contains fat base and has certain hydrophilicity, pellets are more sensitive to water at high temperature. When the moisture content exceeds the limit, the molecular weight of pet plastic will decrease during processing, and the product will become colored and brittle. . Because of this, the materials must be dried before processing. The drying temperature is ℃, hour or more, generally ℃, hour. The air shot method can be used to check whether the material is completely dry. Pay attention to different drying temperatures and time limits to ensure that the plastic bottles produced have good product functions.
, Injection molding machine selection. Because pet plastic bottles have a short stabilization time after melting point and high melting point, it is necessary to choose an injection system with more temperature control sections and less self-friction heat generation during plasticization, and the actual weight of the product cannot be less than the injection volume of the machine/ .
, detention time. Do not use too long a residence time to prevent molecular weight drop. Try to avoid temperatures above ℃. If the downtime is less than minutes. It only needs to be air shot; if it exceeds minutes, clean with viscosity pe, and reduce the barrel temperature to pe temperature until the machine is turned on again. Strict control should be carried out on the residence time of plastic bottles. Different temperatures need to be processed differently, and the time limit should be strictly controlled.
, matters needing attention. The recycled material should not be too large, otherwise it is easy to cause 'bridging' at the unloading place and affect plasticization. When recycling plastics, strictly control the number of recycled materials to ensure the plasticization quality of plastics. If the mold temperature is not well controlled or the material temperature is not properly controlled, it is easy to produce white fog and opacity. The mold temperature must be strictly controlled, otherwise there will be undesirable events. The mold temperature is low and average, the cooling rate is fast, and the product is transparent with less crystallization.
, mold and gate design. Pet plastic preforms are generally formed by hot runner molds. It is better to have a heat shield between the mold and the injection molding machine template, the thickness of which is about mm, and the heat shield must be able to withstand high pressure. Exhaust must be sufficient to avoid local overheating or chipping, but the depth of the exhaust port should generally not exceed .mm, otherwise flash will easily occur. The production process of pet plastic bottles requires strict quality system maintenance to ensure that the produced plastic bottles have good product quality and guarantee. The production process is complicated, and different production processes need to be strictly controlled to ensure that each process is carried out in strict accordance with the standards.
etPlastic bottles have better rheology in the molten state, and the pressure has a greater effect on viscosity than temperature. Therefore, the pressure is mainly used to change the mobility of the melt. Plastic bottles have different usage conditions in different environments...
The rheology of pet plastic bottles in the molten state is better, and the influence of pressure on viscosity is greater than that of temperature. Therefore, pressure is mainly used to change the mobility of the melt. Plastic bottles have different usage conditions in different environments, so the rheology and viscosity of the plastic bottles are effectively controlled in the molten state.
, processing of raw materials. Because pet plastic bottle macromolecule contains fat base and has certain hydrophilicity, pellets are more sensitive to water at high temperature. When the moisture content exceeds the limit, the molecular weight of pet plastic will decrease during processing, and the product will become colored and brittle. . Because of this, the materials must be dried before processing. The drying temperature is ℃, hour or more, generally ℃, hour. The air shot method can be used to check whether the material is completely dry. Pay attention to different drying temperatures and time limits to ensure that the plastic bottles produced have good product functions.
, Injection molding machine selection. Because pet plastic bottles have a short stabilization time after melting point and high melting point, it is necessary to choose an injection system with more temperature control sections and less self-friction heat generation during plasticization, and the actual weight of the product cannot be less than the injection volume of the machine/ .
, detention time. Do not use too long a residence time to prevent molecular weight drop. Try to avoid temperatures above ℃. If the downtime is less than minutes. It only needs to be air shot; if it exceeds minutes, clean with viscosity pe, and reduce the barrel temperature to pe temperature until the machine is turned on again. Strict control should be carried out on the residence time of plastic bottles. Different temperatures need to be processed differently, and the time limit should be strictly controlled.
, matters needing attention. The recycled material should not be too large, otherwise it is easy to cause 'bridging' at the unloading place and affect plasticization. When recycling plastics, strictly control the number of recycled materials to ensure the plasticization quality of plastics. If the mold temperature is not well controlled or the material temperature is not properly controlled, it is easy to produce white fog and opacity. The mold temperature must be strictly controlled, otherwise there will be undesirable events. The mold temperature is low and average, the cooling rate is fast, and the product is transparent with less crystallization.
, mold and gate design. Pet plastic preforms are generally formed by hot runner molds. It is better to have a heat shield between the mold and the injection molding machine template, the thickness of which is about mm, and the heat shield must be able to withstand high pressure. Exhaust must be sufficient to avoid local overheating or chipping, but the depth of the exhaust port should generally not exceed .mm, otherwise flash will easily occur. The production process of pet plastic bottles requires strict quality system maintenance to ensure that the produced plastic bottles have good product quality and guarantee. The production process is complicated, and different production processes need to be strictly controlled to ensure that each process is carried out in strict accordance with the standards.
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