METHOD OF FIXING LID MATERIAL TO PAPER CUP, METHOD OF MANUFACTURING SEALED PAPER CONTAINER AND SEALED PAPER CONTAINER

摘要

PROBLEM TO BE SOLVED: To provide a method of fixing a lid material which can secure sealability and is excellent in the manufacturing cost and production efficiency.SOLUTION: A lid material 10 covers the upper surface of a flange part 11. The lid material 10 is heat-sealed to the upper surface of the flange part 11 with application of heat to the outer surface of the lid material 10 along the entire upper surface of the flange part 11. Then, internal heat generation is caused with application of an ultrasonic wave to the step portion of the flange part 11 and its neighboring range, and the lid material 10 within the range is pressed toward the upper surface of the flange part. The step portion is filled with a melted thermoplastic resin 15. An indentation 10A appears on the surface of the lid material 10 within the range of application of the ultrasonic wave.SELECTED DRAWING: Figure 5