双向拉伸聚酯薄膜横拉工艺研究

Study on the process of BOPET thin-film tentering stretching

通过对采用"一纵一横"逐次拉伸工艺生产双向拉伸聚酯薄膜的横向拉伸工艺研究,归纳出横向拉伸倍率与薄膜断裂强度、伸长以及薄膜横向厚度均匀性的相关性;分析总结出横向拉伸温度与进入横拉前薄膜结晶度的经验关系;提出了热定型时间、温度的确定原则;归纳出热定型松弛率与薄膜收缩率之间的关系;提出了横向拉伸与热定型过程中的弓曲现象对薄膜横向性能不均匀分布的影响及改善途径。

Through the investigation on the tentering stretching process of BOPET film which produced by gradual stretching process as ＂first longitudinal stretching and then tentering stretching ＂, this paper deduces the following the relevant relationships, that is, the relationship between tentering stretching ratio and intensity at film break, the relation- ship between elongation and film transverse uniformity, and also between heat setting relaxation ratio and film shrinkage rate. Meanwhile, the relationship between the tentering stretching temperature and film crystallizing rate before TDO are both analyzed and summarized. Besides, it put forth a principle of judging the heat setting time and temperature. Bowing effect to film transverse properties＇ uneven distribution and its corresponding improving method are beth brought forward during the process of tentering stretching and heat setting.