| 摘要 |
PURPOSE:To provide the title compsn. having excellent surface strength, durability, smoothness and adhesion to plywood, containing alpha- or beta-type hemihydrate gypsum, an aq. melamine(/urea co-condensate) resin and a natural high-molecular gypsum coagulation retarder. CONSTITUTION:100pts.wt. alpha- or beta-type hemihydrate gypsum (A) having a particle size passing through a 100-mesh sieve or mixture thereof with a pigment (A) is blended with 20-100pts.wt. (on a solid basis) aq. melamine resin (B-a) obtd. by reacting formaldehyde with melamine in a molar ratio of 1.5-3 at a pH of 6-9 and at 50-98 deg.C or melamine/urea co-condensation resin (B-b) obtd. from urea and melamine in a molar ratio of 0.2-4, 0.25-1pt.wt. (on a solid basis) natural high-molecular gypsum coagulation retarder (C) and optionally water (D) in such an amount as to give a viscosity of 20-100P. |
