| 摘要 |
PROBLEM TO BE SOLVED: To provide a paperboard with a V-shaped groove cut in which is inexpensive and light-weight and produces no poisonous gas in incineration. SOLUTION: The V-shaped groove 5 is cut in the paperboard 4 formed by pasting an inner cardboard 2 and an outer cardboard 3 on the inner and outer surfaces of embossed paper 1 respectively, and then the paperboard is folded up.
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