PVC sealing strip extrusion foam what is the reason?
Raw material has moisture. Exceed the standard
Raw material needs drying
In addition to some raw materials damp, containing more volatile will cause PVC edge banding in extrusion process will blister, there is a more prone to this phenomenon, namely: lack of thermal stability lead to PVC decomposition bubble. Lack of PVC thermal stability for several reasons: 1. heat stabilizer unqualified or improper selection; 2. heat stabilizer; 3. processing temperature setting is not reasonable, mainly temperature too high; 4. screw extruder of high speed; 5. formula system inside and outside lubrication or collocation unreasonable amount; 6. main raw materials such as stability PVC deficiency. In addition, reasonable mixing processing conditions will greatly reduce the volatile substances in raw materials.
