CPP薄膜专用树脂的结晶性能及加工应用

Crystallization character and processing of polypropylene special resin for cast films

用差示扫描量热仪和偏光显微镜研究了流延薄膜专用无规共聚聚丙烯树脂在不同降温速率下的结晶性能及结晶形态,并分析了在实际加工应用过程中不同冷辊温度对薄膜性能的影响。结果表明:试样的降温速率越快,形成的晶体尺寸越小,且结晶度越低,当降温速率由5℃/min增加到40℃/min时,结晶度由38.15%降至33.18%;在流延膜的实际生产中,加工温度及其他条件一定时,当冷辊温度超过30℃,薄膜的透明度和落镖冲击强度明显下降,拉伸强度缓慢上升,热封温度也升高。

Crystallization character and crystal morphology of polypropylene random copolymer for cast films at different cooling rates were studied by differential scanning calorimeter and polarized light microscope. The influence of different temperatures of cooling roll on film properties during processing was analyzed. The results show that the crystallite size becomes smaller and the crystallinity decreases as the cooling rate gets faster. The crystallinity lowers from 38.15% to 33.18% when the cooling rate rises from 5 ℃/min to 40 ℃/min. The transparency and impact strength of the films dramatically declines, the tensile strength enhances slowly and the sealing temperature increases in case the temperature of the cooling roll exceeds 30 ℃ while setting processing temperature and other conditions at given values.