Injection stretch blow molding is widely used in the packaging of food, medicine, cosmetics and daily chemical products. It has both distinct advantages and limitations. Generally, when evaluating how to package a product, it is necessary to conduct a detailed analysis of the product's specific use requirements, characteristics, costs, etc., and then evaluate and select according to whether the characteristics of various bottle production processes meet the requirements. The following is divided into five parts to introduce some application cases and design ideas of injection stretch blow molding in various fields.
·Common cases of injection stretch blow molding
·The difference and application of one-step method and two-step method
·Note-Pull-Blow Process Control Points
·Development Trend of Injection Stretch Blow Molding and Its Production Technology
·Appreciation of injection stretch blow molding
1. Common Cases Of Injection Blow And Injection Stretch Blow Molding
Injection stretch blowing is a process in which the preform is first injected by an injection molding machine, and the hot parison is stretched longitudinally, and then compressed air is introduced to stretch it transversely to obtain a product with the same shape as the mold cavity. According to the product molding process, it can be divided into one-step injection stretch blow molding process and two-step injection stretch blow molding process.
1). Application of one-step injection stretch-blow PET bottle in pharmaceutical oral liquid packaging
Injection stretch-blow PET Bottles are widely used in Pharmaceutical Packaging, and are often used in the packaging of pharmaceuticals including oral solids, oral liquids and eye drops. Different uses have different requirements for bottles.
Taking the injection stretch blow PET bottle for oral liquid drug packaging as an example, the application and general design ideas of the one-step injection stretch blow PET bottle in drug packaging are introduced:
(1). The material and performance of the bottle meet the national requirements for oral liquid packaging bottles.
(2). Convenient transportation, packaging and consumer use.
(3). The bottle is beautiful in appearance and has corporate LOGO graphics.
You Can Refer To The Following Ideas:
(1). The material of the bottle can be evaluated, and the materials that can be used are glass and plastic. However, glass is not convenient for packaging, transportation and safe use due to its large proportion and fragility. There is no special reason to choose plastic materials as much as possible.
(2). Selection of specific materials and production processes. Usually the two are related. Considering the packaging of oral liquid drugs, PET materials can be considered. PET materials have excellent gas barrier properties and chemical stability, and can meet the national regulatory requirements for oral liquid drug packaging. At the same time, PET material has good surface gloss and impact strength, which is not only beautiful but also meets the packaging and transportation requirements. In addition, the versatility and cost of PET also have advantages.
In terms of molding process, one-step injection stretch blowing process can be considered, and the mouth size and thread accuracy can be well guaranteed. It can be directly matched with the lid to seal without using gaskets or inner plugs. Convenient and cost-effective. At the same time, the one-step injection stretch blowing process completes the injection parison and stretch blow molding actions in the same equipment, ensuring the hygiene of the product. It is more conducive to the packaging of medicines.
(3). For the appearance design of the product, the mouth of the bottle can adopt a circular thread structure, which is simple and beneficial to mold design, process molding and packaging sealing effect. Compatible with PP/HDPE safety cover. The appearance of the bottle body is relatively flexible, and can adopt traditional cylindrical or other shapes.
(4). For secondary processing, scale lines can be engraved on both sides of the mold clamping line, which is convenient for quantitative use each time. At the same time, brand information such as simple words or patterns can also be engraved on the body and bottom of the bottle. For secondary processing, due to the higher requirements for hygiene and safety of medicines. Generally, a simple surface labeling method is used to give information such as the product brand and various descriptions. Less used for other secondary processing.
(5). For the design of the number of mold cavities, for one-step injection stretch blowing, the price is generally higher due to more mold parts. The mold with more cavities has higher production capacity and lower unit product manufacturing cost, but the initial mold cost is relatively large. Molds with fewer cavities have lower production capacity and higher unit product manufacturing costs, but the initial mold cost investment is relatively small. In this case, the annual quantity of 5 million bottles uses a 6-cavity mold, and the initial mold investment and output are more suitable. The price of the mold varies greatly according to the quality of the mold and the manufacturer. For bottles with a capacity of about 100ml, the output of the one-step injection stretch blowing 6-cavity mold can reach 25,000-35,000 bottles/24H, which is relatively suitable.
Therefore, for this case, the alternative solution is to use a PET bottle produced by a one-step injection stretch blowing process with a scale line or LOGO on the bottle body.
2). One-step injection stretch-blow PET bottle combined with multiple secondary processing effects applied to high-end cosmetic bottles
One-step injection stretch-blow PET bottle combined with a variety of secondary processing technology is also a relatively common packaging method for cosmetics. Different from pharmaceutical or food packaging, pharmaceutical or food packaging bottles pay more attention to the safety and hygiene of bottle materials. The cosmetic packaging bottle is more focused on the beauty and grade of the bottle. Therefore, in addition to ensuring the quality and function of the bottle itself, the application of secondary processing technology for cosmetic bottles is more extensive and diverse.
The following is an example of a plastic bottle used for toner packaging in a cosmetics company:
(1). Basic information of the bottle: the capacity is 120ml, and the weight is 20g. Used in toner packaging.
(2). Bottle material and process: The bottle is made of PET material and one-step injection stretch blowing process, which has the advantages of high transparency and good gloss, combined with the high stability and high precision of the one-step injection stretch blow process. Make the bottle itself more aesthetically pleasing.
(3). Bottle structure: The mouth of the bottle adopts a small-caliber thread structure, and the precise size of the injection stretch blowing process is matched with an LDPE inner plug and a combined outer cap. Form a reliable sealing effect.
(4). According to the bottle size, wall thickness requirements and process requirements. The design weight of 20g can ensure the uniform distribution of the bottle wall thickness, and at the same time, the bottle body has sufficient rigidity and good hand feeling, which meets the rigidity requirements of the bottle body for secondary processing such as bronzing, but does not affect the extrusion of the contents. out.
(5). The bottle adopts three secondary processing techniques, the text description and the bar code part adopts the screen printing process, the key graphics and texts adopt the bronzing process, and finally the bottle is sprayed with gradient colors. With the electroplated combination cap, the bottle as a whole is very beautiful and high-end.
Usually, PET bottles are highly adaptable to secondary processing technology, and the safety and hygiene requirements for bottles are not as strict as those of pharmaceuticals and food, which makes the choice of secondary processing more flexible and diverse. Just in line with the needs of cosmetic packaging, therefore, PET injection stretch blow bottle is more and more widely used in cosmetic packaging.
3). One-step injection stretch blowing PP jars for candy packaging
In the past ten years, the application of bottles in the packaging of food, especially candy, has developed rapidly. In many ways, it has replaced the original composite bag packaging. Compared with traditional packaging, bottle packaging has two advantages. On the one hand, it is beautifully packaged and has a strong three-dimensional effect, and on the other hand, it is convenient to use and store. Therefore, the application of bottle food packaging is becoming more and more extensive.
Especially in recent years, one-step injection stretch blowing PP jars are often used in candy packaging. Compared with other packaging, this type of packaging has the following characteristics and advantages:
(1). Apply one-step injection stretch blowing process, high precision of mouth size and good sealing effect.
(2). The use of PP material has several characteristics and advantages. First, it has high water resistance, which is good for candy protection and prevents moisture absorption; second, the bottle has high rigidity and surface gloss; third, PP material is suitable for forming jars. It just meets the filling requirements of candies.
(3). The bottle mouth does not need to adopt a threaded structure, but only needs to adopt a buckle structure to meet the sealing requirements. At the same time, it is convenient for capping and improves filling efficiency.
(4). Cooperate with the secondary processing technology such as labeling and coating to make the bottle more exquisite.
The above introductions are only the most basic and common applications of injection stretch-blow or injection-blow bottles, and more applications such as: the application of injection-blow bottles in various industries of medicine, food and cosmetic bottles; various ultra-thick, ultra-thin, special-shaped Products and applications of high barrier, special materials, modified materials, etc. The design and application of the product are flexible and diverse, and the appropriate material, molding process, product structure design and secondary processing process should be selected according to the use and requirements of the product.
2. The Difference And Application Of One-Step Method And Two-Step Method
1). Differences and respective characteristics:
Compared with the two-step method, the one-step method is completed in one device from raw materials to finished products. The production process is simple, its controllability is strong, and the precision of the bottle mouth is high. The layout of the one-step three-station model is: the first station injects the preform, the second station stretches and blows the bottle, and the third station takes off the bottle. The advantage is that after the tube blank is injection-molded, the heat retained by itself can be directly stretched and blow-molded, which avoids the disadvantages of the tube blank being cooled first, losing heat, and then reheating, resulting in repeated energy consumption. No secondary heating is required, so energy consumption is low.
One-step injection stretch blow molding:
The two-step method requires preform injection molding first, and then secondary processing on the blow molding machine, blow molding. It is completed twice by the injection molding machine and the bottle blowing machine, and can be produced in-line or in separate lines.
Two-step injection stretch blow molding:
2). What kind of applications are suitable for:
The one-step process is more suitable for medium and small batches and products with high hygiene requirements. Of course, it has greater advantages for heterosexual bottles and thick-walled bottles.
At present, one of the two-step processes is high-speed equipment, which is suitable for mass production of water bottles and beverages. One is low-speed (or semi-automatic) for some small-volume products.
3. Key Points Of Injection-Pulling-Blowing Process Control
1). Selection of raw materials:
It should have good barrier properties, extrusion resistance and environmental stress cracking resistance. In addition, some blow molding containers for packaging special liquid goods also require the plastics used to have chemical resistance, antistatic properties and high burst strength. There are mainly PET, PVC, PP, PC, PETG, PCTG, HDPE, HIPS, PES, PEN, recycled PET, amorphous PET, etc., depending on the stretch ratio, blow-up ratio and specific application of different materials. Choose a different material, choose a different material.
2). Parison forming requirements:
·High transparency, homogeneous, no internal strain, no defects in appearance.
·Injection parison process control: temperature, pressure, time.
·Stretching temperature: PET and PVC stretching temperature should be 10-40°C higher than Tg. PET is generally 90-110 ℃, PVC is generally 100-140 ℃. The stretching temperature of
crystalline plastics such as PP is 5-40°C lower than the melting point. Generally around 150°C. If the stretching temperature is too high, the orientation is insufficient; if the stretching temperature is too low, the transparency of the bottle will be affected.
·Stretch ratio: large stretch ratio, high tensile strength and impact strength of the bottle, high drop strength, good air tightness, but difficult to operate, easy to break the preform, PET bottles generally take the stretch ratio of 2.0~ 3.0 2
·Blowing pressure: If the blowing pressure is too small, it is not easy to form; if the pressure is too high, the wall thickness of the bottle will be uneven.
·Cooling time: Cooling time varies with the square of the parison wall thickness. The parison wall is thick, the cooling time is long, and the production cycle is long.
4. The Development Trend Of Injection Stretch Blow Molding And Its Production Process
The main machine of one-step injection stretch blowing process equipment is injection stretch blow plastic hollow molding machine and its injection stretch blow mold, which mainly consists of injection device, lifting and transposition device, stretch blow molding device, demoulding device, hydraulic system and air system , electronic control system, microcomputer automatic control system, frame, safety cover, injection preform mold, stretch blow molding mold and other parts, integrated injection stretch blow molding special control computer, frequency conversion controller, electro-hydraulic proportional control system, Some advanced technology equipment such as hot runner mold.
The development of injection stretch blow molding has been due to the needs of the market and the development of filling equipment on the one hand, and the research and development of automatic packaging lines, various new technologies and new materials on the other hand. While various higher requirements are put forward for injection blow and injection stretch blow molding, it also provides more possibilities. Therefore, the development of injection stretch blow molding has the following trends:
1). The application fields are becoming wider and wider, and the total amount is also increasing. In addition to the packaging needs of disposable products such as food, medicine, cosmetics and daily chemicals, other products such as water cups, home appliances, lampshades, etc. will also use the injection stretch blowing process.
2). The products are becoming more and more diversified and exquisite. The appearance of a product determines its attractiveness to a large extent, and the design requirements for products and molds will be further improved.
3). The quality level and requirements are getting higher and higher. On the one hand, consumers, markets and regulations have higher and higher requirements on the quality and safety of bottles. On the other hand, there are various reasons such as application fields, wider sales regions and the development of various high-speed filling equipment. Higher and individual requirements are put forward for bottle quality.
4). In terms of production process technology and materials, equipment with higher speed, more stability, more automation and breakthroughs in various process limits are constantly appearing. Various safer and personalized new materials and modified materials are constantly being developed and applied to the market.
5. Appreciation Of Injection Stretch Blow Molding
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