What are the reasons for the massive use of polypropylene in the meltblown process? What are the characteristics of polypropylene?

Polypropylene is widely used in melt blown technology because it has the following advantages. 1. The viscosity of the polymer may need to be controlled by using an oxidizer or a superoxidant in the extrusion process, or by mechanical shearing of the extruder or controlling the working temperature for thermal degradation to achieve the purpose of regulating the melt viscosity. 2. The molecular weight distribution can be controlled. The meltblown non-woven fabric process requires a relatively tight molecular weight distribution in order to produce uniform ultrafine fibers. The use of new catalytic technology, such as metallocene catalysts, can produce poly with extremely high melt index and extremely narrow molecular weight distribution. Higher melting point The heat resistance of polypropylene is sufficient for most product applications, and it has a wider molten propylene. Therefore, it is very advantageous for the thermal bonding process commonly used in the non-woven fabric process. 4. It is beneficial to make ultrafine fibers. If the polypropylene melt viscosity is very low and the molecular weight distribution is very narrow, the same energy consumption can be used in the meltblown process to make very fine fibers under the same drafting conditions. Therefore, polypropylene The common fiber diameter of meltblown non-woven fabric is 2-5um, or even finer. Since the melt-blown process uses high-pressure hot air drafting, a polymer with a higher melt index is required, which is beneficial to increase production and reduce energy consumption. At present, most of the most used polypropylene chips have a melt index of 400 to 1200g/10min, and their molecular weight distribution is relatively narrow to produce ultrafine fibers with the required linear density. The polypropylene chips used in melt-blown production and processing should have a higher and more uniform melt index, narrow molecular weight distribution, good melt-blown processing characteristics, and more uniform and stable chip quality to ensure the process of melt-blown nonwoven materials stable.