| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the deterioration of initial characteristics over a long period of time by dispersing a specified amt. of high resistance magnetic powder having a specified resistivity in a resin having a specified wt. average mol.wt. SOLUTION: High resistance magnetic powder having >=1×10<5>Ω.cm resistivity is dispersed in a bonding resin having a wt. average mol.wt. of 80,000-150,000 in the mol.wt. distribution of the THF-soluble component by gel permeation chromatigraphy by 150-800 pts.wt. per 100 pts.wt. of the resin to obtain the objective carrier. When the wt. average mol.wt. of the resin is <80,000, the carrier becomes brittle and causes cracking. The cracked carrier sticks to an image, accelerates the wear of a photosensitive drum and damages the drum. In the case of >150,000, it becomes difficult to melt and knead the resin with other material in a producing process, pulverizability is deteriorated and production efficiency is reduced.</p> |
