Studies On Technology And Efficiency Of Tourmaline Modified Melt-Blown Filter Material

The ideal properties of air filtration material are "high filtration efficiency, low filtration resistance". Surface of polypropylene (PP) melt-blown materials is full of electric charge after being charged. Coulomb force of attraction between the charges has made the filtration efficiency of the material increased dramatically without enhance the filtration resistance, thus PP melt-blown materials are widely used in air filtration fields. However, charge stability of PP melt-blown electret materials is greatly affected by environment condition. This article proposed the idea of doping tourmaline particles to PP melt-blown materials to improve the defect, which is based on the spontaneous polarization effect of tourmaline.Firstly, this article studies the surface morphology, size distribution, thermal stability properties of tourmaline particles; analyze the feasibility of doping tourmaline particles to melt-blown technology. Secondly, the compatibility between the tourmaline power and PP was properly resolved by wet modification; then the modified power and PP are blended and extruded by twin-screw extruder to get high concentrated master batch. Finally, the high concentrated master batch and PP are mixed to be blend spinning on melt-blown machine, and then the melt-blown materials with different tourmaline content are obtained, this article test the properties of the materials.According to the above method, this article use two kinds of raw material to prepare tourmaline modified melt-blown filter material, they are PP with melt index(MI) 1800g/10min and 30g/10min. when MI=1800g/10min, this article manufactured five kinds of materials with tourmaline percentage at 0%,1%,2%,5%,8%. While MI=30g/10min, the article manufactured material with tourmaline percentage at 2%.When MI=1800g/10min, fiber diameter of the material increased as the percentage of tourmaline increase, interspaces between the fibers are enlarged and air permeability alter for the better; mechanical property of the material first increase and then decrease with the kick point of 2%. Adding of tourmaline has caused the change of the material's crystal form from mimetic crystal to a crystal, crystallinity of the material is increased and crystallite dimension is decreased. Thermally stimulated discharge (TSD) diagram of the material show that adding of tourmaline increase the charge stability of the material dramatically, which is also checked by filtration test. Filtration efficiency of tourmaline modified melt-blown filter material is dropped a little compare to that of the pure PP melt-blown material, but the filtration resistance is far lower than pure PP melt-blown, and stability of filtration efficiency is enhanced.At the end of this article, properties of tourmaline modified melt-blown filter material get from PP with MI=30g/10min and MI=1800g/10min is compared. The results show that surface of the material exist melt droplet when MI=30g/10min, and fiber diameter of this material is bigger, interspaces between the fibers are even bigger too. a crystal of the material is more consummate than the material when MI=1800/10min; both the crystallinity and crystallite dimension of the material is increased, which makes the material more brittle and cause the mechanical property of the material decrease. Compared to the materials when MI=1800g/10min, the filtration efficiency of the material drops a lot with lower filtration resistance and higher stability of filtration efficiency.