Plastic mold manufacturers, analysis of the selection skills of different properties of plastics
Injection molding manufacturers use different methods when selecting plastics with different properties. Through in-depth understanding of the material properties of raw materials, they can provide customers with better product material configuration scheme. This paper will discuss the skills of injection molding manufacturers in selecting thermosensitive plastics and hydrolyzable plastics, as well as the improvement scheme for different hygroscopicity of plastics, hoping to provide some reference for readers.
1、 Heat sensitive plastics and easily hydrolyzed plastics
Thermosensitive plastic refers to the plastic that is sensitive to heat at high temperature. When it is heated for a long time or the feed inlet section is too small and the shear effect is large, it is prone to discoloration, degradation and decomposition. Such plastics are called heat sensitive plastics, such as rigid polyvinyl chloride (PVC), polyvinylidene chloride, vinyl acetate copolymer, Polyoxymethylene (POM), polytrifluoroethylene, etc. The decomposition of thermosensitive plastics will produce monomer, gas, solid and other by-products, some of which have corrosive or toxic effects on human body, equipment and mold. Therefore, attention should be paid in the process of mold design, injection molding machine selection and molding. It is suggested to select screw type injection molding machine to ensure that the section of the gating system is large enough. The mold and barrel should be chrome plated to avoid dead corner stagnation, strictly control the molding temperature, and add stabilizer to the plastic to reduce its thermal sensitivity. Even if some plastics (such as polycarbonate (PC)) contain a small amount of water, it will decompose under high temperature and high pressure. This property is called easy hydrolysis, so it needs to be heated and dried in advance.
2、 Hygroscopic plastics
Due to the existence of various additives, hygroscopic plastics have different affinity for water, so plastics can be roughly divided into two types: hygroscopic, adherent and neither hygroscopic nor easy to adhere to water. The water content in the plastic should be controlled within the range allowed by the injection molding manufacturer, otherwise, under high temperature and high pressure, the water will turn into gas or cause hydrolysis reaction, resulting in foaming, decreased fluidity, and poor appearance and mechanical properties of the resin. Therefore, hygroscopic plastics need to be preheated by appropriate heating methods and specifications according to the requirements before use, and at the same time, re hygroscopic plastics should be prevented during use.
The selection skills of plastics with different properties are analyzed. When selecting plastics with different properties, injection molding manufacturers need to take corresponding measures according to the characteristics of plastics to ensure product quality and production efficiency. By understanding the characteristics of plastic such as heat sensitivity, easy hydrolysis and moisture absorption, processing manufacturers can provide customers with more professional and high-quality plastic material selection schemes. I hope this article can enlighten readers and provide some suggestions for the development and technology improvement of the plastic processing industry