水溶性アクリル樹脂を用いたアルミナ懸濁液とグリーンシートの性質に与える中和剤添加方法の影響

Abstract

The effect of adding methods of neutralizer of ammonium hydroxide on the rheological behavior of alumina/water suspension with acrylic polymer and the properties of green sheets prepared from the suspension was investigated. The acrylic polymer used in the present work had the acid value of 20mgKOH/g and glass transition temperature of -15 degrees Celsius. The viscosity of aqueous polymer solution increased from 0.1 to 10.0 Pa·s with the added amount of ammonium hydroxide, indicating that the polymer was a kind of polyelectrolyte. The neutralizer was added (1) after the preparation of the suspension, (2) during the preparation of suspension, and (3) prior to the preparation of suspension i. e., mixed with the aqueous polymer solution. With method (1), the suspension required a long period of time to have a stable viscosity because the viscosity increased after the addition of ammonium hydroxide and then gradually decreased with the maximum viscosity of suspension at 24 h after the mixing. The measurement of adsorbed amount of polymer on Al2O3 suggested that neutralization of free polymer occurred competing the polymer desorption from Al2O3. On the other hand, with methods (2) and (3), the viscosity did not change with time. The packing degree of green sheets prepared from the suspension was large in the order of (1), (2), (3), indicating that the adding method of ammonium hydroxide greatly alters the properties of the suspension and green sheets.