| 摘要 |
<p>A ceiling tile of gypsum and cellulose fibers formed into a board by initially mixing the fibers and gypsum in a water-based slurry that is felted and thereafter pressed and dried with a desired board thickness, the dried board being processed to form a plurality of holes in a face thereof through at least the majority of the thickness of the board, the collective volume of the holes being sufficient to reduce the weight of the board by at least 10% and increase the NRC exhibited by the board over that which would otherwise be found in a board of the same composition without such holes.</p> |
