How Should PVC Sheath Foam Board Break?

Here are some possible causes and solutions:

1. Formula problem

· Improper ratio of foaming agent and foaming regulator: excessive foaming agent or insufficient foaming regulator will lead to insufficient melt strength and easy to burst bubbles. Adjust the ratio of the two and use a blowing agent with higher melt strength.

· Improper selection of resin: different types of PVC resin have an impact on foaming properties, and the resin type suitable for foaming should be selected, such as SC-7 type.

2. Improper processing temperature control

· High temperature: resulting in melt degradation, strength reduction, appropriate reduction of processing temperature.

· Too low temperature: poor plasticization, low melt strength. Appropriately increase the screw temperature to ensure that the melt is fully plasticized.

3. Improper use of molds

· Wrong choice of die: Misuse of thick die in the production of sheet metal, or vice versa, will lead to uneven discharge, bubble bursting, correct choice of die, to ensure that the thickness of the plate matches.

4. Calcium carbonate is added too much

· Excessive addition of calcium carbonate will reduce the melt strength, resulting in. Burst. Control the amount of calcium carbonate added, and ensure that its particle size is moderate, good activity.

5. Lubricant problem

· Insufficient external lubrication: it is difficult to control the temperature in zone 5 of the extruder and easy to overtemperature. Appropriately increase the amount of external lubricant.

Insufficient internal lubrication: the surface is difficult to control the thickness, performance. The plate is thick in the middle and thin on both sides. Adjust the amount of internal lubricant.

6. Uneven mixing

Mixing temperature is low, time is short or the amount of mixing in a single pot is too much

It will lead to uneven dispersion of the mixture components. Strictly implement mixing operation procedures to ensure uniform mixing.

7. Improper gaps in shaping templates

· Too large or too small clearance will lead to uneven sheet thickness or bubble breaking. Adjust the formwork clearance to ensure uniform sheet shrinkage during cooling.

Through the above measures, can effectively solve the problem of PVC skin foam board bubble breaking. In actual operation, it should be analyzed and adjusted according to the specific situation to achieve the best production effect.