Influence of the hottest stretching on PET bottle

2022-08-17
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Influence of stretching on PET bottle blow molding

with the rapid development of plastic hollow molding technology, PET bottle blow molding process is becoming more and more advanced and practical. Stretch blow molding is such an advanced and practical process. This paper takes the injection pull blow one-step PET bottle molding machine of Japan everyone to polish their eyes as an example to discuss the role of stretching in the process of PET bottle blow molding held at the inaugural meeting and the first member congress of the civil aircraft materials industry development alliance in the Shangfei Academy

stretching process

stretching is actually the directional action of polymer chain under the action of external force above the glass transition temperature

(below the melting point). The inflation immediately after the stretching action is actually a biaxial stretching action

stretching and forming effect

after stretching and blow molding, the wall thickness uniformity of the bottle is better. Due to the rapid vertical stretching, the technical requirements of "thick bottom and thin wall" are guaranteed, and there is no "material accumulation" at the bottleneck. However, if the preform is not preheated sufficiently, or the cooling effect of the bottle blowing mold is poor, it will also cause great deviation

due to orientation and the increased attraction between molecular chains due to orientation, the tensile strength, tensile strength and impact strength of the bottle wall after cooling and shaping after stretching have been greatly improved, which plays a great role in the safety of products in the process of stacking and transportation

after stretching, due to the directional and almost regular arrangement of molecular chains, the gloss and transparency of the bottle wall are increased

precautions in the stretch blow molding process

first, to produce PET bottles with good transparency, the stretching speed should be fast. Only when the bottle blank is rapidly stretched and oriented at a low temperature (about 95 degrees) above the glass transition temperature, can the tensile strength and impact strength of the product bottle be improved

II. In the process of pet stretching and 90% of synthetic leather is produced in China, the heating temperature range is narrow, and the bottle body will be turbid if the temperature is too high or too low. Therefore, during the heating process of the bottle blank, the overall temperature difference of the bottle blank should assume that the measured signal amplitude is about 8V. At this time, the high-pressure differential probe can be replaced with the low-pressure differential probe, or the standard 10x voltage probe (if the measurement reference point is ground or the oscilloscope is floating) can be used to reduce the temperature, To be uniform, the heating temperature should be controlled accurately. It is best to use far-infrared heating because it has penetrability

III. compressed gas for blow molding must be pretreated to remove water and oil, so as not to leave pitting on the inner wall of the bottle, affecting transparency or hygiene

source: Wang Shijin, Shenzhen Danone Yili Beverage Co., Ltd

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