Process Problems and Solutions of PVC Transparent Sheet

PVC calendered transparent sheet is one of the main varieties of rigid PVC. It is usually produced by conical twin-screw extrusion. Common problems encountered in the production process are bubbles, more crystal points, and the yellowish color of the sheet. According to our experience, here are the reasons and solutions.

Yellow color problem

1. The stability of PVC resin is poor. Even if the brand of PVC has been used all the time, it may be caused by the PVC resin, because the quality may vary in different batches.
2. Insufficient PVC stabilizer
3. There is a problem with the temperature controller

The displayed temperature is lower than the actual temperature, and the PVC will decompose and turn yellow if the temperature is too high. At this time, it is necessary to recheck the calibration temperature controller.

Bubbles

1. Excessive moisture in PVC raw materials: If the raw materials are damp in summer or rainy days, the water may not be fully discharged in the barrel, and the heat will expand, and then air bubbles will be formed in the sheet.
2. The additives may contain too much water.

You just need to remove moisture from the raw material via prolong the mixing time of the heating mixer and use a cooling mixer.

Too many crystal points, also known as fisheye

Here are the common reasons for crystal point: some PVC resins are not plasticized, or the plasticization is not good. If the quality of PVC resin is OK, you can try the solutions below:

1. Prolong the mixing time and increase the mixing temperature to promote the absorption of additives. In addition, high-quality mixing units should be used.
2. Mixed ingredients can be left to ripen for half a day or a day before use.
3. The setting temperature of the barrel can be increased, as well as the screw speed and the head pressure, which can improve the plasticizing performance.
4. In terms of formula, we must carefully choose the appropriate additives and the number of additives. We must choose carefully and find a better balance between price and performance.

In summary, the above reasons should be comprehensively considered to choose the optimal solution. Some solutions have contradictory relationships, such as increasing the temperature may cause the sheet to turn yellow, adding more stabilizers may cause cost increases, etc.

Welcome to contact TopJoy Chemical if you need any help with the PVC application.