| 摘要 |
PURPOSE:To improve bubble stability without impairing water repellency and the flowability of a gypsum slurry by emulsifying waxes, styrene/maleic anhydride copolymer, water soluble alkaline compd., and PVA in water. CONSTITUTION:The water repelling agent is obtd. by emulsifying (A) the waxes of 40 to 90 deg.C m.p. (e.g.; paraffin wax), (B) the styrene/maleic anhydride copolymer of 800 to 100000molwt., (C) the water soluble alkaline compd. (e.g.: NaOH) of 0.3 to 3 times the volume of the component B, (D) the PVA having 10 to 80cps viscosity of 40% aq. soln. at 20 deg.C, and (E) a hydrocarbon resin (e.g.; cumarone/indene resin) of 500 to 3000mol.wt. in such a manner that the weight ratio of A:E attains 100:0 to 30:70, the weight ratio of A+E:B attains 1:0.01 to 0.7 and the weight ratio of A+B:D attains 1:0.01 to 1. The water repelling gypsum compsn. is then obtd. by compounding 0.5 to 20 pts.wt. (solid content) with 100 pts.wt. gypsum. |
