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The hottest questions about PET bottle embryo prod

2022-10-02

Detail

About the problems that should be paid attention to in the production process of PET bottle embryo

Pet (polyester) beverage bottles have only been developed in China for more than ten years, while hot filled PET beverage bottles have a shorter history in China, only about six years, but the momentum of development is fierce, surpassing most other packaging containers. As we all know, tea drinks and fruit juice drinks are the focus of beverage development, and most of the packaging containers are filled with pet hot, and the proportion has a growing trend. The general production process of PET beverage bottle is: injection molding into bottle embryo - heated bottle embryo is longitudinally stretched - horizontally stretched - blow molding. If the final molding in this production process adopts mechanical cold setting, once the temperature of PET bottle reaches the pet glass transition temperature (78 ℃), its molecular chain will relax and the bottle will shrink seriously. Therefore, this kind of bottle is only suitable for cold filling beverages. During the stretching and shaping process of the above process, the hot filling bottle is always at a high temperature (about 140 ℃), and the PET molecular chain is shaped at a high temperature in a loose state. Finally, a large number of neat and dense knots are produced in the bottle body, and the knot degree can reach 30% - 45%, which makes the bottle have high heat resistance and become a hot filling bottle with practical significance

at first, consumers only focused on the quality of the beverage itself, but now they are gradually beginning to pay attention to the outer packaging of the beverage. The quality of PET bottles depends on the quality of the supplied bottle embryo. There are two kinds of bottle embryo injection molding, one is long rubber mouth, the other is short rubber mouth. Domestic bottle embryo manufacturers choose short rubber mouth bottle embryo more, while foreign manufacturers choose long rubber mouth bottle embryo more. The bottle embryo with long rubber mouth is cut off because the rubber mouth at the bottom is cut off, so the tension is evenly distributed in the bottle blowing process, so the quality of the blown bottle will be better, and the cut part can be recycled, which is conducive to saving the cost of raw materials. Today, with the increasing shortage of oil resources, domestic manufacturers will prefer the bottle embryo with long rubber mouth. The quality control of bottle embryo in the production process depends on the degree of control to avoid scratching during the transportation process. At present, most domestic manufacturers use belt conveyor for bottle embryo conveying, which is a relatively old method of conveying technology. Generally, pay more attention to some basic configurations of the experimental machine. The disadvantages of this conveying are as follows:

when the bottle embryo comes out of the injection molding machine, the temperature is 45 ℃ - 55 ℃. Falling directly on the belt will cause bumps between bottle embryos

in addition, the bottle embryo is piled up disorderly on the belt, and the bottle embryo is not very uniform when cooled

when the bottle embryo comes out of the injection molding machine, there may be quality problems with the embryo injected into a certain mold cavity. It is difficult to judge which mold cavity has the problem

when the injection molding machine injects the bottle embryo, a certain the first mock examination cavity may form a cavity, which is arranged disorderly. If the counting is still based on the number of injected cavities, the counting will be inaccurate

for belt conveyor, the quality control of bottle embryo should be completed manually. First, the quality is difficult to control, and second, too much personnel contact is easy to cause pollution

now Japan, South Korea and Taiwan, China generally adopt the method of chain plate conveying bottle embryos with bottle mouths clamped in a certain order. The production process is as follows:

bottle embryo forming machine - manipulator to take out all the glue mouth machine - front conveying of finished products - bottle mouth finished products machine - rear conveying of finished products - detection machine - counting and packing device

the advantages of this conveying method are as follows: they are forming a fire partnership:

1. The manipulator takes out the bottle embryo from the injection molding machine, and the position of each bottle embryo is numbered. The bottle embryo is taken out by a manipulator instead of falling directly to avoid scratching. Because the position of each bottle embryo has a number, when there is a problem with the injection molding machine, we can accurately find out which mold cavity has the problem

2. The bottle embryo is transported by clamping the neck of the bottle embryo through the plate chain, so that the bottle embryo is transported in a certain order by pulling the electrical switch on the panel. In this way, the bottle embryo is cooled evenly and easy to count. The counting error per 10000 bottle embryos is within ± 5

3. The whole production line adopts automation and is equipped with a small number of personnel