A highly transparent water-soluble film is provided. The water-soluble film contains a PVA resin as a major component, and has not more than 50 dark defects each having a diameter of 1 to 5 mm per a 5 cm × 5 cm area thereof as observed under crossed Nicols after being uniaxially stretched under the following conditions (α):
(α) a test piece cut out of the water-soluble film to a size having a length of 25 cm and a width of 13 cm is clamped with chucks spaced 11 cm from each other longitudinally of the test piece in a stretching machine, and is uniaxially stretched at a stretching rate of 3 mm/second to a stretch ratio of 1.2 at a temperature of 23°C at a humidity of 50%RH.
提供了一种高度透明的
水溶性薄膜。该
水溶性薄膜的主要成分是 PVA
树脂,在下列条件下进行单轴拉伸后,在交叉尼科尔斯条件下观察到,在 5 厘米×5 厘米的面积上,暗缺陷不超过 50 个,每个暗缺陷的直径为 1 至 5 毫米(α):
(α)将从
水溶性薄膜上切割下来的长 25 厘米、宽 13 厘米的试片用夹头夹在拉伸机中,试片纵向的夹头间距为 11 厘米,在温度为 23℃、湿度为 50%RH、拉伸率为 1.2、拉伸速度为 3 毫米/秒的条件下进行单轴拉伸。