Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or... – Method of use – kit – or combined with marking instrument or...
Reexamination Certificate
2002-08-16
2004-09-14
Schilling, Richard L. (Department: 1752)
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
Method of use, kit, or combined with marking instrument or...
C503S207000, C503S208000, C503S214000, C430S339000, C430S964000
Reexamination Certificate
active
06790809
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a heat-responsive-discoloring coloring composition capable of providing prints recyclable by heat treatment and thus suitable for detecting the thermal history of such articles as electronic appliances, food, etc., and a heat-responsive-discoloring coloring element and a method for detecting the thermal history of an article using such a heat-responsive-discoloring coloring composition or element.
BACKGROUND OF THE INVENTION
With OA equipment widely spreading and information technology (IT) rapidly progressing in recent years, offices are flooded with papers, causing serious social problems in the treatment of waste papers increased accordingly. Also, attention is paid to environmental problems of the conservation of forest resources, etc. Against such backdrop, development is actively carried out particularly to provide the technologies of recycling copy papers, and hydrolyzable toners, toners decolored by light, etc. are disclosed in JP 7-120975 A, JP 7-301952 A, etc. Also, toners discolored by heating are described in Takayama, et al “Polymer Preprints, Japan” Vol. 47, No. 9 (1998), page 2063, etc. Further proposed is a method for discoloration of coloring components comprising an electron-donating, organic color former and a phenolic material or another acidic material by heating together with a decoloring agent (JP 57-59079 B, etc.). Though various discoloration methods are proposed, dry treatment is preferable for the simplicity of treatment.
With respect to discoloration by dry treatment, several methods were proposed, and main methods among them are;
(1) Methods using heat-decolorable dyes (U.S. Pat. Nos. 3,769,019, 3,821,001, 4,033,948, 4,088,497, 4,153,463 and 4,283,487, JP 52-139136 A, JP 53-132334 A, JP 54-56818 A, JP 57-16060 A and JP 59-182436A, etc.), or dyes decolored by corrosive gases generated from counter salts while heating (U.S. Pat. No. 4,347,401, etc.);
(2) Methods for discoloration when heated in the presence of agents for generating carbanions by heat and dyes (U.S. Pat. Nos. 5,135,842, 5,258,274, 5,314,795, 5,324,627 and 5,384,237, European Patent 605286, JP 6-222504 A and JP 7-199409 A);
(3) Methods using dyes comprising leuco dyes and acids vaporizable or decomposable by heating for generating a color-developed state by their combination (JP 10-16410 A and JP 10-287055 A);
(4) Methods using dyes discolored by light, such as an o-nitroarylidene dye or an o-nitro-o-azarylidene dye (U.S. Pat. No. 3,984,248 and JP 54-17833 A), dyes having cleavable N—O bonds (U.S. Pat. No. 3,770,451), chrominium-type cyanine dyes (JP 2-229864 A), anionic dyes containing iodonium salts as counter ions (JP 59-164549 A), etc.; and
(5) Methods using (a) photosensitive halogen-containing compounds (JP 57-20734 A and JP 57-68831 A), azide compounds (JP 63-146028 A), ketone-based sensitizing compounds (JP 50-10618 A), mesoionic compounds (U.S. Pat. No. 4,548,895) or iodonium compounds (U.S. Pat. No. 4,701,402), and (b) dyes which are decolored by reaction with active species generated by irradiating and/or heating the above compounds, or by interaction with the above compounds in excited states.
The above methods (1) to (3) are easy because discoloration occurs when heated. However, a discoloration reaction is likely to occur during storage in these methods, failing to exhibit functions when necessary. It has also been found that in a case where a reaction accompanied with gas generation at the time of heating is used, the gas likely forms bubbles, resulting in image defects.
The methods (4) and (5), in which discoloration occurs by light irradiation, are free from the above problems. However, because a large amount of irradiation rays are needed for discoloration in these methods, photo-discoloration is likely to occur, and it takes much time for the treatment.
OBJECT OF THE INVENTION
Accordingly, an object of the present invention is to solve the problems of the above prior art technologies, thereby providing a heat-responsive-discoloring coloring composition that is easily discolored or decolored by a dry treatment, and a heat-responsive-discoloring coloring element comprising a heat-responsive-discoloring coloring layer containing such a heat-responsive-discoloring coloring composition, and further a method for detecting the thermal history of an article using such a heat-responsive-discoloring coloring composition or such a heat-responsive-discoloring coloring element.
SUMMARY OF THE INVENTION
As a result of intensive research in view of the above object, the inventor has found that by adding a polymer having a glass transition temperature (Tg) of 60° C. to 200° C. to a discoloring coloring composition, it is possible to obtain a heat-responsive-discoloring coloring composition, which is colored at a temperature lower than its discoloration initiation temperature (T) of 60° C. to 200° C. and substantially discolored at a temperature equal to or higher than the discoloration initiation temperature (T), and which does not recover its color once discolored, even when its temperature is lowered to a temperature lower than the discoloration initiation temperature (T) again. The present invention has been completed based on this finding.
Thus, the heat-responsive-discoloring coloring composition of the present invention is colored at a temperature lower than its discoloration initiation temperature (T) and substantially discolored at a temperature equal to or higher than the discoloration initiation temperature (T), and does not recover its color once discolored, even when its temperature is lowered to a temperature lower than the discoloration initiation temperature (T) again, the discoloration initiation temperature (T) being 60° C. to 200° C., and the heat-responsive-discoloring coloring composition comprising a polymer having a glass transition temperature (Tg) of 60° C. to 200° C.
The heat-responsive-discoloring coloring composition of the present invention preferably comprises at least an electron-donating, organic color former (coloring compound) and an acidic compound. The acidic compound is preferably a phenol compound. The heat-responsive-discoloring coloring composition of the present invention preferably contains a hydrophilic binder. The above polymer is preferably in the form of dispersed particles having an average particle size of 0.01 &mgr;m to 1 &mgr;m.
The heat-responsive-discoloring coloring element of the present invention comprises a substrate and a heat-responsive-discoloring coloring layer coated on the substrate, the heat-responsive-discoloring coloring layer comprising the above heat-responsive-discoloring coloring composition.
A method for detecting the thermal history of an article according to the present invention comprises the steps of applying the above heat-responsive-discoloring coloring composition to the article, and measuring the color concentration of the heat-responsive-discoloring coloring composition to detect the thermal history of the article. Another method for detecting the thermal history of an article according to the present invention comprises the steps of positioning the above heat-responsive-discoloring coloring element near the article, and measuring the color concentration of the heat-responsive-discoloring coloring composition to detect the thermal history of the article.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The heat-responsive-discoloring coloring composition of the present invention is in a colored state at 25° C., while it is irreversibly discolored at a temperature equal to or higher than the discoloration initiation temperature (T), which is 60° C. to 200° C., and it contains a polymer having a glass transition temperature (Tg) of 60° C. to 200° C. Detailed explanation will be made below with respect to the heat-responsive-discoloring coloring composition of the present invention, and a heat-responsive-discoloring coloring element and a method for detecting the thermal history of an article using the heat-responsive-discoloring coloring composition.
Fuji Photo Film Co. , Ltd.
Schilling Richard L.
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