| 摘要 |
PURPOSE:A magnetic substance, obtained by cultivating magnetotactic bacteria collected from ponds, lakes, etc., in a nutrient culture medium, having an extremely fine and uniform particle diameter as well as good purity and applicable as an additive for toners. CONSTITUTION:Water containing magnetotactic bacteria is separated from sludge water collected from ponds using a magnet and an inorganic salt, vitamin, etc., are added to the resultant filtrate water to carry out cultivation in a culture medium. Spiral magnetotactic bacteria Aquaspirillum magnetotacticum are isolated from the culture medium. The resultant bacteria are then cultivated in a nutrient culture medium with preferably <=0.1wt% salt concentration at 6.0-7.5pH at about room temperature under slightly aerobic condition to give magnetic iron oxide. The resultant magnetic iron oxide in an amount of preferably 40-90pts.wt. and antioffset agent in an amount of 0.5-8pts.wt. are blended with 100pts.wt. binding resin to give a blend, which is then melt kneaded, cooled and subjected to a method for pulverizing, classifying, etc., to afford the aimed magnetic toner. |
