Al₂O₃微粉体の射出成形性に対する粒子表面改質の効果

抄録

The effect of surface treatment of Al₂O₃ powder has been studied on the moldability of mulled materials of oxide powder and resin for injection molding. Al₂O₃ powder was surface-treated by boiling with stearylamine dissolved in toluene for two hours. The amount of surface-adsorbed stearylamine was measured by thermogravimetric analysis. Comparison of wettability of treated and untreated powders for water or acetone showed that the treated powder is more lipophilic because of surface adsorbed stearylamine. Materials for injection molding experiments were prepared by mulling treated and untreated Al₂O₃ powders with polyethylene resin in a volume fraction of Al₂O₃ powder ranging from 50 to 80%. The dispersion of Al₂O₃ powder in resin was estimated from thin sections of these mulled materials with a microscope and by image-processing of the micrographs. The surface treated powder exhibited better dispersion than untreated one. Mulled materials of the surface-treated powder showed markedly large plasticity. For example, a mulled material of 50vol% of surface-treated powder showed about 10⁴ times larger plasticity than that of a material of untreated powder. Even in high powder concentrations, such as a mulled material of 80vol% of the treated powder showed 10 times larger plasticity than that of a material of 50vol% of the untreated powder.