Technological Problems & Solutions for the Extrusion Production of PVC Transparent Sheet
1. Color yellow problem
The reasons and solutions are as follows:
First, PVC itself is poor. If it is a new PVC resin manufacturer, it may be that the PVC itself is not stable and can be changed the PVC. However, even the used brand PVC can also be caused by PVC resin itself, even if the PVC produced by the same manufacturer,the quality of different batches may also be different.
Second, lack of stabilizers, or quality problems of stabilizers
Third, the temperature controller problems, shows the temperature is lower than the actual temperature is too high will cause PVC decomposition, yellow.At this time need to re-check the more accurate temperature controller. The method is very simple, more accurate with a mercury thermometer. In actual production, due to loose thermocouple, stuck on the material and other reasons, will cause the temperature controller display temperature and the actual gap. In addition it is recommended to use high-quality temperature controller, often the foreign brands RKC, the European mother dragon, domestic Shanghai Yatai.
2. The sheet has small bubbles
1. PVC raw water too much, such as in the summer of rainy days, damp raw materials, water may not be fully discharged in the barrel, heated expansion, and then the formation of bubbles in the sheet.
2. Other additives may also contain too much water.
In summary, the solution measures can be used: appropriate extension of the mixing time of the heat mixer, the mixing temperature is generally maintained at 105-110 degrees, and the use of cooling mixer, cold mix temperature is generally 45 degrees and below appropriate. Can effectively remove the moisture of raw materials.
3. MICROTEK points sheet called fisheye exceed the standard.
The common cause of crystal point is that some PVC resin particles are not plasticized or plasticized well. The reasons are: the quality of PVC resin itself is not good or the 5 type resin powder is used too much. In the condition that PVC resin is not replaced, the solution is:
First, prolong mixing time and improve the mixing temperature, promote the absorption of additives. And using high quality mixing unit, the preplasticizing effect of the mixing unit is irreplaceable.
Second, mixed material can be placed for half a day or a day, let the cure, and then use the.
Third, can improve the setting temperature of barrel, increasing the screw speed, increasing the die pressure, further improve the plasticizing property.
Fourth, in the formula, we must carefully select the appropriate additives, and the amount of additive, the additive market confusion, differences in product quality, choose carefully, find a good balance between price and performance.
We should consider all above reasons, and then choose the optimal solution. There are contradictions in some solutions, such as increasing the temperature may cause the sheet to yellow, and more stabilizers may lead to higher costs. It is only in practice to find the way forward.