| 摘要 |
<p>PURPOSE:To prevent a thermally welded portion and the vicinity thereof from being torn by a method wherein a vinyl chloride resin sheet whose peripheral edge protrudes outside thick paper is disposed on both surfaces of the thick paper, and portions to be thermally welded and the vicinity of the inner peripheries thereof are preliminarily heated before they are thermally welded. CONSTITUTION:A vinyl acetate adhesive is applied on both surfaces of thick paper 1, and vinyl chloride resin sheets 2 and 3 are disposed on said surfaces respectively through the intermediary of the adhesive. Thereafter the sheets are contact-bonded by rollers or the like and dried in this state. Next, the dried article is transferred onto a bottom tool 11, and the portions to be thermally welded of the peripheral edges of the vinyl chloride resin sheets 2 and 3 and the vicinity on the inner peripheral side thereof are preliminarily heated by a heater 14 for preliminary heating. Then, the heater 14 being withdrawn, a top force 12 is lowered from above and thereby the upper vinyl chloride resin sheet 2, the thick paper 1 and the lower vinyl chloride resin sheet 3 are pressed to contact with each other, while the portions to be thermally welded of the peripheral edges of the vinyl chloride resin sheets 2 and 3 are pressed on the bottom tool 11 side by an electrode 13 and are thermally welded by high-frequency heating.</p> |
