This is the part two of first production procedure China cheap durable pvc seed trays roll material

2). The sheet has small bubbles

1. Excessive moisture in PVC raw materials. On a rainy day in summer, the raw material is damp, and the moisture cannot be fully discharged in the barrel.

2. The problem of the factory's own formula. This is each factory's own production secret issue.

3). The number of crystal points in the sheet exceeds the standard

Some PVC resins are not plasticized due to poor quality, or the plasticization is not good.

At this time, it is necessary to properly extend the mixing time and increase the temperature of the mixture to promote the absorption of additives. The mixed raw materials can also be left for half a day or a day, let them ripen before use. It can also increase the barrel temperature, increase the screw speed, increase the head pressure and other measures to further improve the plasticizing performance.