| 摘要 |
PURPOSE:To eliminate the curling-up of the end of a film at thermal shrinkage by a method wherein main sealing is performed with ultrasonic wave at the middle of an overlapped portion of both the ends of the film and at the same time auxiliary sealing is also performed with ultrasonic wave at the upper side end edge of the film. CONSTITUTION:A main sealing part 2 is obtained by sealing the middle of an loverlapped portion of both the ends 3 and 4 of a shrinkable film 1 with ultrasonic wave. The slight crosswise distortion of said main sealing is permissible. the numeral 5 denotes an auxiliary, sealing produced by ultrasonic sealing along the upper side end 3. In addition, the auxiliary sealing 5 may be done simultaneously with or after the main sealing 2. Further, the intermittent auxiliary sealing 5 may be acceptable except the continuous auxiliary sealing 5. No curling- up of the end of the shrinkable film occurs by heating due to the auxiliary sealing provided along the end as mentioned above except the main sealing. |
