Cleaning and liquid contact with solids – Processes – Including work heating or contact with combustion products
Reexamination Certificate
1999-01-22
2001-08-21
El-Arini, Zeinab (Department: 1746)
Cleaning and liquid contact with solids
Processes
Including work heating or contact with combustion products
C134S005000, C134S015000, C134S032000, C134S030000, C510S174000
Reexamination Certificate
active
06277208
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of decoloring a decolorizable image forming material.
In recent years, the amount of various kinds of information has significantly increased by spread of office automation, and so the level of information output has also increased. The information output is represented by display output and hard copy output from a printer onto paper sheets. The display output, however, requires a large scale circuit board in a display unit. This brings about problems of portability and cost. Regarding the hard copy output, a large quantity of paper as a recording medium is being consumed with increase in the information output amount. Therefore, the hard copy output is expected to be a problem with respect to conservation of natural resources. In addition, recycling of paper sheets once printed by a printer or a copying machine is expensive, since much of a bleaching agent and water are required for the recycling and consumption of electric power is enormous. Under such a situation, it is considered to decrease consumption of paper substantially by using decolorizable image forming material to print information on a paper sheet, restoring a blank sheet of paper by decoloring the formed image, and reusing the paper sheet.
Heretofore, ink which can be decolored on heating has been proposed in, for example, Published Unexamined Japanese Patent Application No. 7-81236. The ink includes a color former such as a leuco dye, a developer, and an organophosphoric compound having a decoloring power.
When such image forming material is used, however, decoloring can be done insufficiently and, as a result, a paper sheet is hard to return to the blank state. For this reason, decolorizable image forming material cannot have been put into practical use.
BRIEF SUMMARY OF THE INVENTION
It is, accordingly, an object of the present invention to provide a method of decoloring a decolorizable image forming material which can be decolored easily after image formation and the decolored state of which can be maintained stably, thereby making it possible to reuse paper sheets.
According to an aspect of the present invention, there is provided a method of decoloring an image forming material formed on a paper sheet and containing a color former, a developer and a decolorizer, comprising the steps of: heating the image forming material; bringing a solvent into contact with the image forming material for decoloring the image forming material; and removing a residual solvent from the paper sheet.
According to another aspect of the present invention, there is provided a method of decoloring an image forming material formed on a paper sheet and containing a color former, and a developer, comprising the steps of: heating the image forming material; bringing a solvent containing a decolorizer into contact with the image forming material for decoloring the image forming material: and removing a residual solvent from the paper sheet.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
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patent: 5736286 (1998-04-01), Kaneko et al.
patent: 6017386 (2000-01-01), Sano et al.
patent: 6022423 (2000-02-01), Bhatia
patent: 2-188294 (1990-07-01), None
patent: 4-247984 (1992-09-01), None
patent: 7-81236 (1995-03-01), None
patent: 410036721 (1998-02-01), None
Fujioka Sawako
Machida Shigeru
Naito Katsuyuki
Okuyama Tetsuo
Sano Kenji
El-Arini Zeinab
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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