Bubble breathing occurs when the volume of air in the b […]
Bubble breathing occurs when the volume of air in the bubble changes periodically. This causes variations in the film's thickness. A solution for this problem is to increase the speed of the melt as it exits the die. Another problem is called helical instability, which occurs when one side of the bubble cools more than the other. This leads to a ring of air that can eventually collapse. To avoid this problem, you can increase the output of the extruder machine and lower the melting temperature.
The polymer used in a Blown Film Extruder Machine is a polymer, such as PVC, which is a thermoplastic. Various materials can be used in the process, and many types are blended together in multi-layer film structures. Some common materials used in this process are polyethylenes, as well as EVOH and PP. Since some of these materials cannot gel well, delamination can occur. To avoid delamination, special adhesive resins are used in between these thin layers, called "tie layers".
The blown film process is an advanced process that allows manufacturers to manipulate the mechanical properties of the final plastic film. By combining two or more molten layers, the process can create complex multilayer structures. In fact, commercial equipment is capable of coextrusion of seven to eleven layers. A three, five, or nine-layer blown film die is typical of the multilayer bubble equipment. However, this machine differs from other extrusion processes.
