Application and Opening Mechanism of Silica Opening Agent in Casting Polypropylene Film
Five types of casting polypropylene film(CPP)/SiO2 masterbatches were prepared and cast into film via using four types of SiO2 opening agents and one imported opening agent AB905 under the same processing conditions through twin-screw extruder.The results show that all five opening agents can meet the anti-adhesion and opening performance requirements of CPP film,and the dynamic/static friction coefficient is reduced to less than 0.12(belonging to high smoothness).The anti-adhesion test under a load of 7 kPa at 50 ℃ for 24 h shows that there is no adhesion between the CPP film which is made with K45 and AB905,while the pure PP film has some adhesion.AFM test shows that there are pits near the submicron SiO2 opening agent particles,and these pits play a key role in reducing negative pressure and van der Waals force,thus reducing the adhesion of PP films.Finally,based on experimental data,a model of anti-adhesion and opening principle suitable for CPP films was proposed for the first time,it is expected to be used to guide the production of opening agents with higher anti stick opening efficiency.