| Research Abstract |
Application of toners, which had been charged before use, was tried to the development in photocopy machines and laser printers. First, toners were charged by tribocharging, corona-charging and electron beam irradiation, and charge keeping characteristics of toners were examined. The toner, when charged by tribocharging, kept its charge for the longest period among the three ways of charging. Plasma treatment was applied to the toners to improve its charge maintaining ability. As a result, fluorine plasma treatment was found to increase the time constant considerably for charge decay from charged toner. In addition, the fluorine plasma treatment shifted charging tendency of the toner in negative direction. On the other hand, argon plasma treatment of toners decreased their charge maintaining ability and shifted their charging tendency in positive direction. However, the fluorine plasma treatment gave wrong influence of fixing.
Thermally stimulated charge decay (TSCD) measurements were carried out on charged polymer layers to study the charge decay mechanism from toners. The trap depths in polypropylene were 0.99eV, 1.2eV and 0.19eV for positive corona-charging, negative corona-charging and tribocharging, respectively. These values are large enough for long term charge maintaining in toners. Thermally stimulated current (TSC) measurements were made on polymers containing charge control agent (CCA). Trapping sites were found to be located between the polymer and CCA.
Finally, change in toner charge associated with handling, such as agitation, transport, etc. was examined, which should be cleared for practical applications.
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