The Research Of Processing And Molding Polypropylene Isolation Film

In this paper, use a kind of drawing level Polypropylene which is homo-polymer, and study the process of using this kind of Polypropylene resin and nucleating agent to prepare Polypropylene micro-porous membrane.Mix Polypropylene and nucleating agent, use the single screw extruder to pile out them and get polypropylene casting film, and then put the casting films in oven to make spherulites grow, at last, use uniaxial tensile machine to stretch casting films, and finally get Polypropylene micro-porous membrane. Studied the preparation process of Polypropylene micro-porous membrane, and discussed the effects of oven temperature and the time that casting films stay in the oven to the spherulites and crystallization situation of casting films, and also the effects of the technological conditions of uniaxial tensile machine to the thickness and porosity factor of Polypropylene micro-porous membrane were discussed. Results show that:When sodium benzoate was used as nucleating agent, we need a solvent to dissolve sodium benzoate, and then mix the solution and Polypropylene, in this way, sodium benzoate can distribute well in Polypropylene; Prepare magnesium oxide master batch, and then mix the master batch and Polypropylene, in this way, magnesium oxide can be evenly dispersed in Polypropylene; Adding nucleating agent in Polypropylene can make more perfect spherulites in the casting films, and also increase the amount of spherulites; When the oven temperature is 90℃, it can make the spherulites grow well; When the time that casting films stay in the oven is 7d, the size of spherulites is larger; Compare to adding 0.1 phr nucleating agent, adding 0.2phr agent can make the spherulites size smaller and increase the spherulites number; Compare to using sodium benzoate as nucleating agent, using magnesium oxide as nucleating agent can make the spherulites bigger; The number of spherulites in the casting film has nothing to do with the crystallinity of the casting film; When polypropylene casting film thickness too thick, using uniaxial tensile machine to stretch the casting film just can get membrane with crackles but no millipore; When the temperature of uniaxial tensile machine increased, the Millipore in the membrane can easily shaped, the aperture will increase, and also the porosity factor will increase, but the thickness will reduce; When the rotate speed of uniaxial tensile machine increased, the aspect ratio of the Millipore in the membrane will increase, the aperture and porosity factor will increase too, at the same time the thickness will reduce.