Preface

Injection blow molding is a method of producing hollow plastic bottles through injection blow molding equipment; Extrusion Blowing Molding is currently the main plastic hollow blow molding process. The two have both great similarities and many differences. These two molding processes are widely used in various fields that we come into contact with daily, such as packaging container blow molding production for food, medicine, daily chemical packaging, and petrochemical products.

1、 The production process of injection blown bottles

(1). Principle of Injection Blown Bottle Production Process

Injection blown molding process (IBM), also known as injection blown molding process. The process principle is to use injection blow molding equipment to heat and melt the resin and inject it into the blank mold to form a blank. Then, the blank attached to the core rod and with a certain temperature is transferred to another blow molding station mold, and compressed air is introduced into the blank to blow and expand the blank. Then, the required hollow product is obtained by cooling and shaping the blow molding mold. The formation of products mainly goes through the following four core processes: 1. resin plasticization and melting; 2. Injection molding blank; 3. Blow molding; 4. Product demolding.


At present, the mainstream equipment in the injection blow molding process market is mainly horizontal three-station rotary molding equipment, with the principle shown in the above figure.

2. Characteristics of injection blowing process

Compared to the extrusion blowing process, injection blown bottles have the following process characteristics.

Advantages:

1. The product is formed in one go without any leftover materials (excluding tail trimming), resulting in a higher resin forming rate and no need for post processing, resulting in a more efficient utilization of raw materials.

2. The surface of the product is smooth and beautiful.

3. The product preform adopts injection molding, with stable quality, weight, and process.

4. The product mouth or threaded part adopts injection molding, which has higher dimensional accuracy and is suitable for producing products with high sealing requirements.

Limitations:

More suitable for producing small capacity bottles, not suitable for producing bottles larger than 300ml.

For special-shaped bottles or flat bottles, it is not easy to form.

The net weight of the product is fixed and cannot be randomly adjusted.

The cost of mold development and maintenance is relatively high, and the cycle is long.

The production efficiency is relatively lower than that of extrusion blowing.


2、 The Manufacturing Process of Squeeze Blown Bottles

Extrusion blow molding process (EBM), also known as hollow extrusion blow molding process. The process principle is to use a blow molding equipment extrusion system to heat the resin into a molten state and then extrude it from the mold head to form a tubular billet, which naturally droops into the mold to form a blow molding billet; After the mold is closed, the blowing air rod blows compressed air into the inner part of the mold through the air nozzle to expand the mold. Then, the mold is cooled and shaped to obtain the required hollow product. After the product is formed, it is automatically cut on the machine or the edge is removed through secondary processing in the later stage.

Fluoride bottles and multi-layer barrier bottles, both of which are barrier functional containers, have their own characteristics. With this question in mind, we consulted relevant experts.

Firstly, let's talk about the technology of fluoride bottles. The source of fluoride gas and patented technology is "American Gas Company". Initially, BOXMORE Company in the UK invested in Jiangsu Longdeng Doctor Mo Packaging Materials Co., Ltd. (JRB) with this patented technology in China. Fluorine gas+nitrogen protection, the mixed fluorine gas is blown into shape through a hollow shaped blowing device (patented 30 years ago, whether the patent protection period has expired is unknown). After blowing into shape and maintaining pressure, online fluorination treatment is completed, and a layer of "polytetrafluoroethylene" barrier layer is formed on the inner wall. The complete solution for this patent includes a relatively complex wind pole structure and a recycling system. Fluorine gas is highly toxic and can be fatal if inhaled by the human body, so the reliability of this process device is very important. Previously, fluorine gas was imported, but it is said that now fluorine gas can be obtained through domestic military enterprises, greatly reducing costs. The acquisition of nitrogen is relatively convenient, and the control of the proportion and accuracy of fluorine gas addition, as well as the control of the fluorination process and recovery (without leakage) are also key to this process. There are currently imitations of fluorination process devices in China (with unknown effects).

The bottle treated with fluoride forms a polytetrafluoroethylene barrier layer on the inner layer of the bottle. The thickness of the PTFE barrier layer is generally around 7-8, which is relatively thin μ m. The thicker one is about 10 μ About m. The blocking effect of polytetrafluoroethylene layer is relatively ideal, but the blocking effect does not gradually decay. Once the blocking breakthrough is formed due to long-term corrosion, the blocking effect will flow like a dam breaking for thousands of miles. For example, if the content is toluene, there may be no problem for one year, but after more than one and a half years, the fluoride layer is corroded and broken through, immediately losing its barrier effect.
The advantage of fluoride bottles is that the overall process is relatively simple, but the fluoride device, including the basic device, requires higher requirements and is expensive because it is necessary to ensure that there is no fluoride leakage. On the surface, the cost of fluoride bottles is relatively low, but if the auxiliary costs around them are included, it may not necessarily be low.

Multi layer barrier bottles usually use EVOH (nylon is also used for lower requirements) as the barrier layer. This material is water resistant, so it is usually placed in the middle and does not blend with other materials (PE/PP). Therefore, it is necessary to have a bonding layer, and EVOH is also more expensive. However, the disadvantage of this process characteristic also becomes its advantage. Placing EVOH in the middle is not easy to form a breakthrough, and the long-term blocking effect is relatively reliable. The bonding effect at the seam is a risk, and the utilization of the recycled layer is also a hassle (the compatibility of recycled EVOH). There is no risk of death or injury to the human body. And with the continuous progress of multi-layer technology, the amount of EVOH layer is decreasing and the cost is decreasing. Therefore, the use of multi-layer barriers will become a trend in the future.

Another fluorination process is post fluorination treatment. Place the formed bottle into a sealed fluorine gas container for fluorination treatment. Although the cost may be lower, as the manufacturing chain becomes longer, it is still necessary to carefully consider the risk of fluorine gas leakage.