System control is the key to ensure the long-term stabi […]
System control is the key to ensure the long-term stability of pvc profile quality. It includes four items: “formulation quality, process quality, appearance quality, physical and chemical indicators”. The first two are the premise and basis of the latter two, and also the quality control and technical management. The top priority.
The uniformity of the mixing of the resin and the auxiliary agent and the apparent density of the mixture have a great influence on the impact strength of the PVC. PVC processing temperature has a certain range, the temperature is too high, PVC is easy to decompose; the temperature is too low, PVC plasticization is not sufficient, and uneven dispersion of various components will lead to increased brittleness. The main engine speed reflects the shearing action of the extruder on PVC. If the rotation speed is too large and the shearing force is increased, the low temperature performance and the welding angle strength of the product will be lowered. The high molding pressure is beneficial to improve the mechanical properties of the profile, especially the low temperature impact strength. The profile forming cooling function is to cool and stretch the stretched macromolecular chain in time to meet the requirements of the product. The slow cooling allows the macromolecular chain to stretch for a sufficient time, so that the internal stress is small, which can reduce the warpage, bending and shrinkage of the product, thereby improving the impact strength and the welding angle destructive force of the product.
Discuss that the formula cannot be separated from the raw materials. The quality of the formulation does not depend entirely on the proportion of the components and depends to a large extent on the intrinsic properties and quality of the raw materials. The same as the composite stabilizer, due to the different internal components, will affect the quality of the profile because of the inconsistency with other raw materials. Therefore, when discussing the formula, it must be determined after each raw material model and manufacturer. Xinjiang Tianye Building Materials Co., where the author is located, has been using self-produced pvc resin, CPE uses Weifang Yaxing Chemical Co., Ltd. products, and titanium dioxide uses DuPont products. Therefore, this article only discusses compound stabilizers and increases. Dosing agent.