Polypropylene Foam Sheet Production Technology

Compared with PS and PE, the development of polypropylene (PP) foam as a major member of the semi-crystalline thermoplastic family has been slow, and domestic production has not been achieved yet, but PP foam has many unique advantages: (1) The flexural modulus of PP is about 1.52GPa, which is much higher than that of PE 207MPa. Therefore, the static load capacity of PP foam is better than that of PE. (2) The glass transition temperature of PP is lower than room temperature, so the impact performance of PP foam is better than that of PS. Foam; (3) When PS foam is used above 105°C, it softens and deforms; PE foam is rarely used above 100°C, but PP foam has a high heat distortion temperature (165°C), and it has excellent high temperature resistance. Used in high temperature environment; (4) PP has very good chemical resistance, comparable to PE; (5) Due to the presence of pendant methyl groups, PP is prone to B degradation, and PP foam is easy to recycle and its environment-friendly Better than other foam materials. It is based on the above advantages that the application of PP foam in many industrial fields, especially in the automotive industry and food packaging industry, is very competitive, and it can replace existing PS and PE foams with broad prospects.

However, the extrusion foaming of PP is very difficult. The main reason is that the passability of PP is poor, and the processing window for extrusion foaming is very narrow. Experts have estimated that the temperature suitable for foaming with PP is only 4 °C. When the temperature rises to its melting temperature, the melt elasticity of PP decreases sharply, and the lower melt strength cannot guarantee the tensile stress on the cell walls during bubble growth, resulting in the collapse and collapse of the bubbles, resulting in PP. The open rate of the foam is very high and cannot meet the requirements for use. Therefore, in order to prepare a PP foamed material, it is first necessary to improve its expandability from the viewpoint of raw materials.

The polypropylene foam sheet production technology developed by Beijing Technology and Business University adopts domestically-produced polypropylene and high-melt-strength polypropylene produced abroad. Through optimized design, polypropylene foam sheet can be produced on domestically produced equipment, and the cell density can be achieved. 106/cm3, density as low as 0.6g/cm3. Products can be widely used in the automotive industry and food packaging industry.

Reproduced from: China Plastics Additives Network