Why Does The PVC Foam Board Have Bubbles When It Is Extruded?

What happens when the PVC foam board has bubbles when it is extruded? There are big bubbles, bubbles, yellowing and other problems in the middle of the board. The surface of the board is not smooth because of the excessive lubricant of the PVC foam board. Tianshi wax powder will take you to learn more about it.

PVC foam board extrusion is prone to the following problems:

1. Yellowing of the board surface: The extrusion temperature is too high or the stability of the stabilizer is insufficient. The solution is to lower the processing temperature. If there is no improvement, the formula can be adjusted. The amount of stabilizer and lubricant added can be appropriately increased. It can be changed one by one, which can easily find the problem quickly and solve the problem as quickly as possible.

2. Yellowing in the middle of the board: The main reason is related to the high temperature of the barrel area and the mold temperature. The amount of lubricant is also related, and it is related to the white foaming agent again. It can be treated by adjusting the process temperature or adjusting the addition ratio of white foaming.

3. Plate bending: The main reason is uneven material flow or insufficient cooling. The factors causing uneven material flow generally include large traction fluctuations or uneven internal and external lubrication in the formula. The machine factor is easy to exclude. Formula adjustment generally adjusts the internal lubrication under the premise of minimizing external lubrication, which will have a good effect, while ensuring uniform cooling. The water temperature of the die is generally controlled at 30-40℃ during the production process, and the water temperature of the shaping table is generally controlled at 15-20℃ as the optimal range.

4. Uneven thickness of the plate: uneven discharge, the height of the die lip can be adjusted. If the flow rate is too high, the flow control rod can be adjusted. The formula is adjusted. Generally, more internal lubrication will make the middle thicker, and more external lubrication will make the material discharge faster on both sides.

5. Changes in thickness and texture of the board during shift handover: The main reason is the fluctuation of the mixing raw materials. After the mixing of the previous shift, the interval between mixing and the next shift is long, the hot mixing pot is well cooled, and the first pot of mixing is well pre-plasticized, which is different from the previous mixing. Under other conditions, it is easy to produce fluctuations, which can be solved by adjusting the traction and processing temperature or by standardizing the mixing handover.

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