双向拉伸聚乳酸薄膜的制备

摘要

Domestic and imported polylactide (PLA)were used respectively for pilot plant test of biaxially oriented PLA (BOPLA)filn.The impact of drying conditions,process parameters,and properties of PLA before and after stretching on the properties of the film were investigated.The optimal process conditions of BOPLA molding were explored as well.The results show that the optimal drying conditions of PLA is drying at 80 ℃ for 5 h;the drawn PLA is easier to crystallize than the undrawn PLA.The optimal process conditions of BOPLA molding are listed as follows:the temperature of casting piece roll is from 20 ℃ to 25 ℃;the temperature ranges from 40 ℃ to 75 ℃ at preheating zone,60-70 ℃ at stretching zone,and 20-30 ℃ at setting zone in the process of longitudinal stretching;the temperature ranges from 50 ℃ to 120 ℃ at preheating zone,60-130 ℃ at stretching zone,and 110-160 ℃ at setting zone in the process of transverse tensile;the ratio of longitudinal and transverse draw is 3.0 × 3.0.%以国产聚乳酸(PLA)和进口PLA为原料,进行双向拉伸PLA(BOPLA)薄膜的中试生产,研究了PLA干燥条件、PLA拉伸前后的性能变化,以及工艺参数对BOPLA薄膜性能的影响,并摸索BOPLA薄膜的最佳成型工艺条件.结果表明:PLA的最佳干燥条件是80℃干燥5 h;当温度升高时,经过拉伸的PLA厚片比未拉伸的PLA厚片更容易结晶.BOPLA薄膜成型的最佳工艺参数为:铸片辊温度20～25℃;纵向拉伸时,预热区温度40 ～ 75℃,拉伸区温度60～70℃,定型区温度20～30℃;横向拉伸时,预热区温度50～ 120℃,拉伸区温度60～130℃,定型区温度110～ 160℃;纵、横向拉伸比为3.0×3.0.