Supercritical foaming is a physical foaming technology capable of providing high-quality products. The foaming mechanism fully utilizes the characteristics of supercritical fluids. First, the supercritical fluid is thoroughly and uniformly mixed with the molten raw material. Then, by changing the pressure, the fluid precipitates to form a large number of bubble nuclei. During the subsequent cooling and molding process, the bubble nuclei inside the sol continuously grow and form by adjusting and controlling parameters, ultimately obtaining qualified microporous foamed products. 

Technical Features

Supercritical foaming technology can adjust the pore size and distribution by controlling parameters, thereby regulating the density of the foamed products. The supercritical foaming process involves rapid changes in pressure and temperature, and the precision and accuracy of controlling these changes affect the quality and yield of the final foamed products. The depressurization rate of supercritical foaming is nearly sonic, with fast phase transition speed, allowing it to quickly skip the metastable region and directly undergo spontaneous phase separation. Commonly used supercritical foaming media are mainly CO2 and N2. CO2 enters polymers faster and has a higher equilibrium concentration than N2, so the quality and uniformity of supercritical foaming products using CO2 as the medium are better than those using N2. After the supercritical fluid is melted with the foaming material, it is divided into three different specific implementation processes according to different application scenarios: completing temperature and pressure changes in the same container (static foaming), continuous extrusion through the extrusion port (continuous foaming), or injection into the mold cavity (mold foaming). 

Technical Advantages

Compared with traditional foaming processes, supercritical foaming has shorter foaming time, finer and purer foam pores, better coloring performance, strong stress structure, no concentration or temperature gradient issues, more uniform pore distribution, and controllable particle size, resulting in products with lower density, better thermal stability, toughness, and sound insulation performance, as well as lower thermal conductivity and thermal conductivity coefficient. Due to the simplicity of the process, lower foaming temperature, less energy consumption, more variables such as temperature, pressure, and auxiliaries available for regulation, and easier adjustment and precise control of parameters, the structure of the final foamed products can be regulated. Most of the supercritical fluid media used are inert, environmentally friendly, non-flammable and non-explosive, with no waste emissions. After the process is completed, there is no residue of formamide, odorless and non-toxic, providing long-term protection for consumers and producers. The production process does not use cross-linking agents, allowing for melt recycling, making it green and environmentally friendly. 

Application Areas

Supercritical foaming technology is an efficient material preparation technology capable of preparing pure foamed materials with food safety grades and good skin compatibility, with finer foam pore structure and more stable performance, making it widely used in various fields such as thermal insulation materials, insulation materials, lightweight automotive parts, lightweight aviation components, sports equipment, shoe materials, ships, 5G, new energy batteries, furniture, decorations, toys, protective equipment, and packaging industries.