Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or... – Having nonchromogenic liquid spread-control or...
Patent
1996-09-18
1998-10-06
Hess, Bruce H.
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
Having nonchromogenic liquid spread-control or...
503201, 503209, B41M 530
Patent
active
058175997
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of international application PCT/JP96/00104 filed Jan. 22, 1996.
The present invention relates to a reversible heat sensitive recording material in which formation and erasion of an image can be carried out by controlling heat energy.
Heat sensitive recording materials generally comprise a support and, provided thereon, a heat sensitive recording layer mainly composed of an electron donating normally colorless or light colored dye precursor and an electron accepting color developer, and, upon heating with a thermal head, a thermal pen, a laser beam or the like, the dye precursor instantaneously reacts with the color developer to produce a record image. These are disclosed in JP-B 43-4160, 45-14039, etc.
Generally, once an image is formed on these heat sensitive recording materials, it is impossible to restore them to the original state having no image by erasing the formed image. Therefore, when information is to be additionally recorded, only the way is to additionally record the information in the portion where no image is formed. Thus, in the case of the area of recording being limited, quantity of recordable information is limited and all of the necessary information cannot be recorded.
Recently, in order to cope with this problem, reversible heat sensitive recording materials in which image formation and image erasion can be repeatedly carried out have been proposed. For example, JP-A 54-119377, 63-39377 and 63-41186 disclose heat sensitive recording materials composed of a resin matrix and an organic low molecular material dispersed in the resin matrix. However, since these methods reversibly change the transparency of heat sensitive recording materials by application of heat energy, the contrast between the image portion and the non-image portion is insufficient.
Moreover, according to the methods disclosed in JP-A 50-81157 and 50-105555, since the images formed change with environmental temperatures, the temperature at which the image-forming state is maintained differs from the temperature at which the image-erasing state is maintained and, at room temperature, these two states cannot be stably maintained for an optional period of time.
Furthermore, JP-A 59-120492 discloses a method of maintaining the image-forming state and image-erasing state by keeping the recording materials in the region of hysterisis temperature utilizing hysterisis characteristics of the color forming component. However, this method suffers from the problems that a heating source and a cooling source are necessary for image formation and erasion, and further the temperature region in which image-forming state and image-erasing state can be maintained is limited to the hysterisis temperature region. Thus, this method is still unsatisfactory to be used in the temperature environment of daily living.
JP-A 2-188293 and 2-188294 and International Patent Laid-Open No. WO 90/11898 disclose reversible heat sensitive recording media comprising a leuco dye and a color developing and erasing agent which causes color formation and color erasion of the leuco dye by heating. The color developing and erasing agent is an amphoteric compound having an acidic group which allows the leuco dye to form a color and a basic group which erases the developed color. This compound carries out color formation and color erasion by preferentially exerting one of the color forming action of the acidic group and the color erasing action of the basic group by controlling the heat energy. This method, however, cannot perform complete switching between color forming reaction and color erasing reaction only by control of heat energy, and both the reactions simultaneously take place in some proportion. Therefore, sufficient color density cannot be obtained and sufficient color erasion cannot be performed. Thus, sufficient contrast of the image cannot be obtained. Furthermore, since the color erasing action of the basic group exerts also on the color formed portion at room temperature, the phenomenon of decrease in density of the
REFERENCES:
patent: 5395815 (1995-03-01), Ikeda et al.
German Search Report dated Jul. 17, 1997, issued in a counterpart foreign application, together with English translation.
Higuchi Masahiro
Iida Kazuyuki
Maruyama Jun
Sano Hidekazu
Shibuya Yukiko
Hess Bruce H.
Mitsubishi Paper Mills Limited
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