| 摘要 |
PURPOSE:To obtain the board equivalent to asbestos-added boards in terms of strength, dimensional stability, etc., by specifying the Blaine value of silica, using a specific ratio of pulp fibers and mica, and specifying the water absorption rate of the pulp in the inorg. compounding of cement by a dry process. CONSTITUTION:The silica having >=10000cm<2>/g Blaine value is used and the pulp fibers are used as reinforcing fibers. The mica of 5 to 20wt.% of the weight of the total raw materials is used as the auxiliary reinforcing fibers. First, 20 to 50wt.% water is absorbed into the pulp and this pulp is uniformly mixed with the other cement compd., the mixture is molded to a board-shaped body by the dry process. The mica prevents the degradation in the strength arising from the shrinkage and deformation of the molding and the water absorption of the pulp, but the effect of preventing the deformation is not obtainable if the amt. of the addition is below the lower limit. An appropriate effect is not obtainable even if the amt. of the addition exceeds the upper limit. The Blaine value of the silica is set at the above- mentioned value to accelerate the curing reaction and to improve the bond strength of the cement matrix, by which the strength is improved synergistically with the intensification of the reinforcement by the pulp. The weight addition is insufficient and the mixing is difficult if the water absorption rate of the pulp is below the lower limit. The moisture administration over the entire part of the compd. is difficult if the water absorption rate exceeds the upper limit. |
