| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat sealing method for a lid material for a sealed container for sealing yogurt, etc., therein, in which even if a surface of the lid material facing the interior of the lid material has a contents-adhesion-preventing layer made of hydrophobic inorganic fine grains that works as foreign matter to impair heat sealing performance, superior heat sealing strength, easy-unsealability, and contents-adhesion-preventing performance are provided, thus offering total satisfaction.SOLUTION: In a heat sealing process, the lid material is heat sealed by two steps consisting of a pre-heating step of heating part of a seal area of the lid material in its width direction to a temperature equal to or higher than the melting start temperature of a heat-sealing layer without applying a substantial seal pressure to the part and a full-scale sealing step of thermally pressurizing the seal area by applying a given seal pressure and heat of a given temperature to the seal area. |
