What is the molding process of plastic bottles2021-04-19 16:51:41
What is the molding process of plastic bottles? Plastics can be made into packaging containers and products with various properties and shapes through various processing methods. There are many molding and processing methods for plastic packaging containers. Commonly used are injection molding, hollow blow molding, and sheet thermoforming. We can choose a reasonable molding method according to the properties of the plastic, the type, shape, use, and cost of the product.
Plastic bottles have many excellent properties and are widely used in liquid food packaging. In addition to the traditional glass bottle packaging of alcohol, plastic bottles have become the most important liquid food packaging container and have a trend to replace glass bottles.
1. The extrusion→blowing process is the most commonly used molding process for plastic bottles. The resin is heated and melted on the plastic extruder and the hollow tube is extruded through the die, and then sent to the metal mold and compressed air is blown into the tube to make the plastic The preform is expanded and placed on the mold, and the product is formed after cooling. It is the main method for producing LDPE, HDPE, PVC small mouth bottles.
2. The injection → blowing process includes two main processes. First, the plastic is melt-injected into a preform with a certain shape, and then the injection mold is removed and replaced with a blow mold while it is hot. Blow molding, and cooling to form a product. It is the main method of producing large-mouth containers. The suitable plastic varieties are mainly PS, HDPE, LDPE, DET, PP, PVC, PAN, etc.
3. The extrusion→pulling→blowing process first melts and extrudes the plastic into a tube blank, and then stretches it longitudinally at a degree of stretching and blows it with compressed air. Finally, it is cooled and shaped and then the mold is opened to take out the finished product. The product has been oriented stretched to improve transparency, barrier properties and strength, and reduce the wood and quality stars. This molding process is mainly suitable for PP, PVC and other plastic bottles. (plastic bottle)
4. Injection → stretch → blow molding The preform is molded by injection, and then stretched and blow molded. It is characterized by high product precision and precise neck size without modification. The container has good rigidity, high strength, and good appearance quality, which is suitable for mass production; its disadvantage is that it is difficult to achieve narrow mouth or special-shaped bottles. This process is suitable for forming PET, PP, PS and other plastic bottles.
5. Multi-layer co-extrusion (Note)→Blowing process requires the molding of a thousand-layer tinged tobacco bottle male.