| 摘要 |
<p>PURPOSE:To give antifungal and fungiproof property to a gypsum board and to effectively use an old liquid of electroless nickel plating liquid which is wasted in a large amt., by compounding a hardly-soluble phosphite into the gypsum board. CONSTITUTION:(A) A gypsum material such as gypsum anhydride, gypsum hemihydrate or gypsum dihydrate, (B) hardly-soluble metal phosphite by 0.5-30wt.% of the gypsum board to be produced, and if necessary, (C) a proper amt. of accelerating agent for hardening, pH controller, thickener, org. natural fiber, synthetic fiber, reinforcing agent, filler, or the like by a proper amt. are compounded with other antifungal fungistat. The component (B) is obtd. by processing an old electroless plating liquid containing sodium hypophosphite as a reducing agent to remove nickel and to desulfurize, then adding at least one of metal selected from calcium, magnesium, zinc and copper to the obtd. soln. essentially comprising sodium phosphite, and effecting the reaction to produce hardly-soluble metal phosphite. These components are mixed in a mixer, uniformly kneaded with addition of a proper amt. of water, molded with an extrusion molding machine, and hardened by drying.</p> |
