What related matters should be paid attention to in the production process of PVC foam board? The following is a detailed introduction by HANGZHOU GEGE PVC foam board manufacturers, hoping to help you.
1. Stability issues. Insufficient stability will affect the entire board surface, the board surface will turn yellow and discolored, and the board will be brittle;
The second is the melt strength problem. Insufficient melt strength will lead to large cells in the PVC foam board and long longitudinal section cells; the direct method to judge whether the melt strength is insufficient is to press the board wrapped on the roll with your fingers behind the three rolls of the equipment during production. If the melt strength is good, you can feel the elasticity when pressed. If it is difficult to bounce after pressing, it indicates that the melt strength is poor.
Third, is the lubrication problem. Lubricants are divided into external lubricants and internal lubricants. External lubricants help the plate to be released from the mold and are good for the smoothness of the surface of the plate. Too few external lubricants make it difficult to control the temperature of the extruder and heat up easily, which will lead to confluence. If the core temperature is high, there will be problems such as large bubbles, string bubbles, and yellowing in the middle of the plate, and the surface of the plate will not be smooth; the internal slip agent is conducive to plasticization, and the fluidity of the melt. The precipitation of the outer slip on the surface of the inner plate of the mold will also show the phenomenon of irregular back and forth movement on the plate surface. If the inner slip is insufficient, it is difficult to control the thickness of the plate surface. The phenomenon of high core temperature. If the dispersion is not good, the surface of the sheet will be uneven.
Fourth, is the problem of dispersion. The increase in temperature will also lead to the decrease in melt strength, the increase of foamed sheet cells, the reduction of the number of cells, the brittleness of the sheet, and the ease to break; the decrease in temperature will also reduce the melt viscosity, and the sheet will have uneven dispersion of cells when the viscosity decreases.