| 摘要 |
PURPOSE:To stabilize the developing performance and fixing performance of a pressure fixable capsuled toner even in case of copying on many sheets of plain paper and improve the shelf stability of the toner by restricting the thickness of the shell substance to a specified relation in accordance with the hardness of the core substance. CONSTITUTION:Supposing the main grain size (grain size occupying the maximum number of grains in the grain size distribution) of a pressure fixable capsuled toner to be (a)mum, the main grain size of the core substance (b)mum, and the hardness of the core substance (y)dmm., the thickness of the shell substance is adjusted to a-b >=0.01, preferably >=0.02mum in accordance with the hardness of the core substance so that the relation represented by the equation is satisfied. The core substance is made of low mol. wt. polyethylene, higher fatty acid or the like having pressure fixability, and the shell substance is made of insulating noncohesive polystyrene or the like having high film forming capacity and high positive or negative chargeability and exerting no unfavorable influence on the pressure fixability of the core substance. Thus, offset to a pressurizing roller, adhesion to a carrier and the surface of a photoreceptor, etc. are prevented. |
