Nowadays, with the rapid development of science and technology, new developments have emerged in the building materials industry and flooring. PVC flooring has added new members to the flooring family. As a product of the high-tech era, it is characterized by green environmental protection, low cost and high cost performance. PVC transparent sheet is one of the main types of hard PVC conical twin-screw extrusion production. Common problems in the production process include: air bubbles, many crystal points, yellowish color of the sheet, etc. Below, the editor will give you a detailed introduction to the causes and solutions of the yellowing of the sheet.
1. Reasons for sheet yellowing:
1. The stability of PVC itself is poor.
If it was just replaced. PVC may be the resin manufacturer's own poor stability of PVC, you can try to replace PVC. However, even for the brands that have been used, even if it is PVC, it is possible that the PVC resin itself is produced by the same manufacturer, because even if it is PVC, the quality of different batches may vary.
2. Insufficient stabilizer
If there is a problem with the temperature controller, the displayed temperature is lower than the actual temperature. If the temperature is too high, the PVC will decompose and turn yellow. At this point, a more accurate temperature controller needs to be rechecked. This method is simple, and it is more accurate to use a mercury thermometer. In actual production, there is a gap between the displayed temperature of the temperature controller and the actual temperature.
2. Reasons for small air bubbles in the sheet:
1. There is too much moisture in the PVC raw material. For example, in the rainy summer day, the raw material is damp, that is, the moisture may not be completely discharged from the barrel, and it will expand when heated, and then generate air bubbles in the sheet.
2. In addition, the water content of additives may be too high.
In summary, the solution can be adopted: Properly increase the mixing time of the hot mixer, and use a cooling mixer. Can effectively remove moisture from raw materials.
3 The number of crystal points in the sheet exceeds the standard, also known as fisheye
Some common causes of crystal points are: PVC resin particles are not plasticized, or the plasticization is not good. The reasons for this are: the quality of PVC resin itself is not good.
.JPG)
3. Under the condition of not replacing the PVC resin, the solution is as follows:
1. Appropriately increase the mixing time and increase the mixing temperature to promote the absorption of additives. And choose a high-quality mixing unit, the preforming effect of the mixing unit on the material is irreplaceable.
2. The mixed raw materials can be left for half a day or a day, let it mature, and then used.
3. It is possible to properly increase the set temperature of the barrel, increase the screw speed, increase the head pressure, etc., to further improve the plasticizing performance.
4. In terms of formulation, we must carefully select the appropriate additives and the amount of additives. At present, the additive market is chaotic and the quality of products varies widely. We should choose carefully and find a better balance between price and performance.
The above is all the content shared today, I hope it will be helpful to everyone!
没有评论:
发表评论