| 摘要 |
PROBLEM TO BE SOLVED: To obtain a broardlike material excellent in strength by providing a number of closed voids in the inside and constituting the material out of a paper panel having a specified apparent density and boardlike shapes at both faces, barrier thin films having a specified vapor permeability laminated at both faces, and cardboard having a specified basis weight. SOLUTION: A boardlike material 1 is constituted of barrier thin films 2 having 0.5 g/cm2/24 hr or less vapor permeability laminated at both faces of a paper panel 10 having 0.15-0.4 apparant density forming boardlike shapes at both faces and having a number of closed voids in the inside, and paper board 3 having 100 g/cm2 or larger basis weight laminated with the films. In case of an apparent density lower than 0.15, the mechanical strength is inferior, and in case of an apparant density higer than 0.4, the whole weight is heavy. Since paper panel 10 absorbs moisture in the air if it is left as it is and a warp arises, it is shielded by the barrier thin films 2. When the vapor permeability exceeds 0.5, there is a fear that a warp arises in the boardlike material 1. In this way, a light weight plate which has a small vapor permeability and no warp, and a large shock-resistance, can be obtained.
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