The Reason Why The Polymerization Of PVC Foam Board Is Too Low
Sep 23, 2022
To improve the melt strength of PVC foam materials and promote the plasticization of PVC, ultra-high molecular weight polymers are added to PVC foam products. The lubrication system is also different. What are the reasons for the low polymerization of PVC foam board?
PVC foam board has the characteristics of waterproof, flame retardant, acid and alkali resistance, moth resistance, lightweight, heat preservation, sound insulation, and shock absorption. It is the deal alternative to sheet metal.
PVC resins are generally divided into three types: emulsion PVC, suspension PVC, and bulk PVC according to their polymerization methods. When producing rigid PVC foam products, if the emulsion method PVC resin is used, a product with uniform cells and a smooth surface can be obtained, but the dimensional stability of the product is difficult to control; and the production cost of the emulsion method PVC resin is high; if the suspension method is used PVC resin, the appearance quality and cell uniformity of the product are slightly worse.
In terms of comprehensive technology, price, and performance, it is advisable to mix the two in a certain ratio, and the ratio can be between 80/20-20/80. The cross-sectional area of the sheet is relatively wide, and the extruder head enters the die to a width equivalent to about 1.3 meters. To obtain fully foamed low-density plastic products, the viscosity of the resin used should not be too high. The dispersion and expansion of the bubbles, and the coordinated pressure of the entire cross-section of the sheet, require high melt fluidity. If the viscosity of the PVC resin is too high, the melt fluidity is poor, the flatness of the board surface is difficult to ensure, and the cells are not easy to expand, resulting in a low foaming ratio; on the contrary, if the viscosity of the PVC resin is too low, the melt strength will be low, which is easy to cause rupture Bubble.
