Study On The Processing Pameters For Producing Meltblown Microfibers Nonwovens

Microfibrous materials have a high application value in the biological medicine; filter material, military and industrial areas. At present, the methods for producing microfibers are fiber alkali deweighting, composite spinning, melt spinning and electrostatic spinning and so on. Melt blowing is one of the most commonly used methods for producing microfiber nonwovens. Although it has been realized industrialization production, but the fineness of fiber is still in microns range. If the fineness of meltblown fiber reduces to the nanometer level, the melt blowing technology will have a broader prospect of application.In this study, the following three aspects of work have been done:Firstly, melting point and the crystallization temperature of polypropylene were tested. Through the analysis the rheology of polymer melt with different temperature condition, the polymer viscosity decreased with the increasing temperature and polymer melt flow rate. By adding cooling masterbatch, polymer melt flow rate can be significantly improved so that the spinning temperature can be reduced by 20～30℃. Meanwhile, the fiber diameter and crystallinity significantly reduced, evenness of fiber web increasedSecondly, the processing parameters including collecting distance, polymer flow rate, polymer temperature, air temperature, air pressure. With the decrease of the collecting distance, polymer flow rate, polymer temperature, air temperature and air pressure increases, the fiber diameter and fiber unevenness reduce. Furthermore, when the air temperature is higher than melt temperature, the fiber diameter reduced significantly. Through orthogonal test we get the optimum process conditions for polymer temperature 270℃, air pressure 0.40 MPa, collecting distance 10 cm, air temperature of 350℃, polymer flow rate 1.3 ml/min. Under these optimum conditions, the fiber diameter obtained is 0.4714μn.Finally, through the study on application of the nanofiber to improve the filter performance, we concluded that with the increase of air pressure, air temperature and melt temperature, the meltblown fiber diameter decrease, which lead to the concentration of the filter pore size distribution, the average of aperture size reduce. Porosity has no significant changes, shows that the permeability of the filter material without change.