| 摘要 |
An insulating board is formed of a low density insulating material, such as polystyrene foam. The board has perforations therein and deformations on its upper and its lower surfaces. A high density material, such as gypsum or artificial resin fills the perforations and deformations and extends over the upper and the lower surfaces of the board and, if desired, over its edges to form a composite sheet. Sheets of paper, plastic or metal may be fixed to the top and to the bottom of the composite sheet. A method of making the sheet involves bringing the board into contact with the material of higher density and allowing it to set or cure.
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