PVC is a very special thermoplastic. Its pure resin is easy to decompose during processing, has poor fluidity, low impact strength and poor weather resistance. Therefore, it is necessary to add various auxiliary materials during the processing to improve its performance. Such as: lubricants, heat stabilizers, impact modifiers, PVC processing aids, etc. In the development and application of PVC processing aids, the product components are roughly classified into the following categories: methyl methacrylate (MMA) / acrylate copolymer, MMA / styrene copolymer, acrylonitrile / styrene, etc. At present, the most used and best effect is MMA/acrylate copolymer.
In the PVC foaming formula, in order to obtain a more uniform, small and independent cell structure, in addition to the use of foaming agents such as: AC, etc., PVC foaming regulators are also used in the general formulation system, and sometimes A foaming accelerator (adjusting the decomposition temperature of the foaming agent) such as a metal oxide such as zinc oxide or lead oxide, an organic acid salt such as zinc stearate, or a urea derivative is added. PVC foaming regulator is actually an acrylate emulsion polymer, which has all the characteristics of PVC processing aids, and its molecular weight is much higher than PVC processing aids. In the PVC foamed product, the purpose of adding the foaming regulator is mainly to increase the melt strength of the melt and prevent the combination of the bubbles to obtain a uniformly foamed PVC foamed product. At the same time, it can also promote the plasticization of PVC and ensure the melt has good fluidity.