| 摘要 |
<p>PURPOSE:To provide a discoloring method which enables re-use of a transcribing material through discoloring of the printing at any time when preservation of the contents is no more needed. CONSTITUTION:A fixed image is discolored when a thermal energy five times or more as large as the energy used to fix a toner image is applied to a transcribing material which retains the toner image after being fixed. The condition of thermal energy at this time is expressed by T1Xt1X5<=T2Xt2, where T1 is heat roll temp. in K deg. in heat fixation operation, t1 is nip stagnating time in msec for it, T2 is heat roll temp. in K deg. at the time of discoloring, and t2 is nip stagnating time in msec for it. The toner to form toner image contains as inevitable an electron donative, coloration type organic compound either colorless or pale, an electron acceptive compound, a compound having a substantially irreversible discoloring effect for the coloration due to these compounds, and a resin as binder.</p> |
