| 摘要 |
PROBLEM TO BE SOLVED: To realize a sealing excellent in sealability by forming a deep-drawn paper tray, and squeezing a flange part with the heat and the pressure generated by an ultrasonic machining to form a smooth surface. SOLUTION: A cardboard on a surface of which a thermoplastic resin is laminated is punched to form a blank, and the blank is fed between a male die and a female die and pressed to form a deep drawn paper tray 2. A flange part of the deep-drawn paper tray 2 is held by an anvil 15 and an ultrasonic horn 16, and pressurized and oscillated to generate the heat inside, and a thermoplastic resin layer on the surface is softened and fluidized to fill an unevenness of the flange part. At the same time, paper is also squeezed through pressurization, and the unevenness of the surface is reduced on the whole to form a smooth surface. A seal excellent in sealability can be obtained, a commodity with liquid content, etc., can be packaged, and the seal can be resistant against the gas substitution or gas flash.
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