The Functional Studies Of The Antibacterial Of PP Filter Material

In recent years, variety of infectious diseases caused by bacteria and viruses through airborne transmission threatened people’s health. And to sterilize directly by convecting air is the most recommended method. Therefore, antibacterial air filtration material become the inevitable demand. Currently, there are many materials with antibacterial function. Among which, silver ions(Ag+) and nano titanium dioxide(TiO2) are the most accepted antibacterial agent. However, the high cost of the silver ions as well as the undefined conclusion whether it could do harm to human body or not made nano TiO2 a better choice in this paper. Nano TiO2 powder was selected as the antimicrobial agent due to its excellent photocatalytic antibacterial property, and PP non-woven fabrics in smallest density was used as raw materials. Then a PP non-woven material with photocatalytic antibacterial function was produced. During the experiments, the process conditions of preparing nano TiO2 dispersion were studied, followed by finishing process conditions, and the main influencing factors of each process. Antibacterial tests showed that the product got good antibacterial effect without ultraviolet radiation, and the antibacterial property still lasts after 10 times washing.1. By filtrating the type, dosage of dispersants, as well as the pH value and Zeta potential of the dispersed system, Polyethylene glycol(PEG) was chosen to prepare the nano TiO2 dispersion. And the optimal process was as followed. 10%(mass percent) of TiO2 powder and 2wt% of PEG were put into 20% ethanol solution, then adjust the pH to 10 with 0.1mol/L NaOH solution. Followed by 30 min magnetic stirring and 20 min ultrasonic dispersion in ultrasonic cell disruptor. Uniform and stable nano-titanium dioxide dispersion could be collected and stored for more than seven days by this process.2. Best technology was concluded by discussing the dipping time and temperature of padding method as well as the baking time and temperature of thermoforming, which was dipping 3min under 45℃ and baking 90 s under 120℃. Under this condition, the nano TiO2 content could reach up to 2.7%, but not washable. After 3 times washing, nano TiO2 fell off from the fiber completely. This means padding process was not suitable for washing resistance.3. By discussing the reaction temperature, time and pressure, the optimum process of supercritical CO2 treatment was obtained as followed. The penetration temperature of supercritical reaction was 100℃, penetration pressure was 30 Mpa and penetration time was 40 min. Under this condition, the fixed content of nano TiO2 could reach 4.5g. After washing, 2.4g was left and the loss rate was just 23%, which means the washing resistance became better.