バレイショデンプンの諸物性におよぼす軽質無水ケイ酸の疎水化物並びに含有水分の影響

抄録

The effect of the addition of light anhydrous silicic acid to potato starch powdes, which improves the lubricating characteristics of drug powders, is usually cancelled by the absorption of moisture. In order to improve this point, hydrophobic light anhydrous silicic acid was used, and prevention of the loss of the lubricating effect by moisture sorption was examined.
1) Moisture sorption of the mixture of dry starch and silicic acid (0.1%) results in the increase of the apparent specific volume and angle of repose, and decrease of dispersibility, with the increase in water content. The resultant mixture shows powder characteristics close to that of starch, that is the lubricating effect of light anhydrous silicic acid is lost. When 0.1% hydrophobic silicic acid is added, its effect was almost the same as when added to moistened starch, and the lubricating effect of hydrophobic silicic acid was not lost due to moisture sorption by starch.
2)Examination of such mixtures by a scanning electron microscope revealed that ordinary light anhydrous silicic acid stuck to starch granules that looked like the moistened thin paper to be stuck when light anhydrous silicic acid experienced moisture sorption, and light anhydrous silicic acid could not prevent the contact of the starch granules. This resulted in the reappearance of powder characteristics in starch itself. In the case of hydrophobic light anhydrous silicic acid, the particles do not stick to or fall from starch granules even after moisture sorption and remain attached sterically to the starch granules the same as after their addition, and prevent the contact of starch granules themselves. This is considered to be one of the reasons why hydrophobic light anhydrous silicic acid does not lose its lubricating effect.