JP3286214B2 - Erasable ink and printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink that can be erased after printing, and a printer using the ink.

[0002]

2. Description of the Related Art In recent years, with the spread of OA, the data amount of various types of information has been steadily increasing, and the output of information has also increased accordingly. The output of information is represented by a display output and a hard copy output to paper by a printer. However, display output requires a large-scale circuit board in the display unit, and thus poses a problem in terms of portability and cost. In addition, in the hard copy output, when information increases, a large amount of paper is used as a recording medium, which is problematic in terms of resource protection. Moreover, recycling paper printed by a printer or copier requires a large amount of bleaching agent and water, so the recycling cost is also high. In view of this, it has been considered that information is printed on paper using erasable ink, and the amount of paper used is substantially reduced by reusing the paper that has been erased and returned to a blank state.

Conventionally, an ink which can be erased by applying heat is disclosed in, for example, JP-A-7-81236. This ink has a color-forming compound such as a leuco dye,
It contains a color developer and an organic phosphoric acid compound having an erasing action.

[0004] However, when an ink made of such a material is used, erasure is insufficient and it is difficult to return to a blank paper state. For this reason, erasable ink has not been put to practical use yet.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink which can be printed with sufficient contrast and which can be erased by heat, making it possible to reuse the paper. Another object of the present invention is to provide a printer using such an ink.

[0006]

SUMMARY OF THE INVENTION The erasable ink of the present invention.
Is a color-forming compound that interacts with
Contains coloring agent and erasing agent selected from sterol compounds
The ink composition to be dispersed in a solvent,
I do. Other erasable inks of the present invention interact and emit.
Coloring compound and developer in color state with cholic acid,
Tocolic acid, testosterone and cortisone and
And an erasing agent selected from the group consisting of these derivatives.
Characterized by being dispersed in a solvent
And

The printer of the present invention has a printing mechanism for printing the above-described erasable ink and a printing mechanism for printing ordinary ink.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The erasable ink of the present invention enables erasure after printing by combining a color former, a developer, and an erasing agent.

First, the operation of the basic components constituting the erasable ink will be schematically described. A color-forming compound is a precursor compound of a dye that forms coloring information such as characters and figures, and a color developer is a compound that develops color by interacting with the color-forming compound (mainly by transferring electrons or protons). It is a compound that colors the compound. Further, the erasing agent is a compound having a property of preferentially dissolving one of the color developer and the coloring compound at the time of melting.

[0010] When these three components are solidified, they can take the following two states. That is, (1) the erasing agent is mixed with an amount of the coloring compound and the developing agent in an amount corresponding to the equilibrium solubility, and an excess of the coloring compound and the developing agent exceeding the equilibrium solubility in the erasing agent is added to the erasing agent. (2) a state in which the color developing compound and the color developing agent form a color due to the interaction, and (2) the erasing agent takes in the developing agent or the color developing compound in a large amount exceeding the equilibrium solubility, and the color is formed. In this state, the interaction between the coloring compound and the developer is reduced and the color is erased.

The state change between the color-developed state and the decolored state is performed according to the following principle. Here, the description will be made on the assumption that the erasing agent preferentially dissolves the color developer when the three-component system is in a molten state in a fluid state. At room temperature, the state in which the phase of the coloring compound and the developer and the phase of the erasing agent are phase-separated is close to the equilibrium state. In this case, the color former and the color developer interact with each other to form a color. From this state, when the three-component system is heated above the melting point,
The color developer is preferentially dissolved in the erasing agent in the fluid state, and loses the interaction with the color forming compound, so that the color erasing state is established. When the ternary system in the molten state is forcibly solidified by quenching, the erasing agent becomes amorphous by taking in a developer amount exceeding the equilibrium solubility and becomes colorless at room temperature. Although the amorphous ternary system is in a relatively non-equilibrium state, the glass transition point T
When the temperature is lower than room temperature, the amorphous state does not easily shift to the equilibrium state.

Next, specific compounds that can be used as components of the ink of the present invention will be described. Examples of the coloring compound used in the present invention include leuco auramines, diaryl phthalides, polyaryl carbinols, acyl auramines, aryl auramines, rhodamine B lactams, indolines, spiropyrans,
Electron donating organic substances such as fluorans.

As specific color-forming compounds, crystal violet lactone (CVL), malachite green lactone, 2-anilino-6- (N-cyclohexyl-
N-methylamino) -3-methylfluoran, 2-anilino-3-methyl-6- (N-methyl-N-propylamino) fluoran, 3- [4- (4-phenylaminophenyl) aminophenyl] amino -6-methyl-7-chlorofluoran, 2-anilino-6- (N-methyl-N
-Isobutylamino) -3-methylfluoran, 2-anilino-6- (dibutylamino) -3-methylfluoran, 3-chloro-6- (cyclohexylamino) fluoran, 2-chloro-6- (diethylamino) fluoran , 7- (N, N-dibenzylamino) -3- (N, N
-Diethylamino) fluoran, 3,6-bis (diethylamino) fluoran-γ- (4′-nitroanilino)
Lactam, 3-diethylaminobenzo [a] -fluoran, 3-diethylamino-6-methyl-7-aminofluoran, 3-diethylamino-7-xylidinofluoran, 3- (4-diethylamino-2-ethoxyphenyl)- 3- (1-ethyl-2-methylindole-3-
Yl) -4-azaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, 3-diethylamino-7-chloroanilinofluoran, 3-diethylamino- 7,8-
Benzofluorane, 3,3-bis (1-n-butyl-2
-Methylindol-3-yl) phthalide, 3,6-dimethylethoxyfluoran, 3,6-diethylamino-
6-methoxy-7-aminofluoran, DEPM, AT
P, ETAC, 2- (2-chloroanilino) -6-dibutylaminofluoran, crystal violet carbinol, malachite green carbinol, N- (2,
3-dichlorophenyl) leuco auramine, N-benzoyl auramine, rhodamine B lactam, N-acetyl auramine, N-phenyl auramine, 2- (phenyliminoethanedylidene) -3,3-dimethylindoline, N, 3 , 3-Trimethylindolinobenzospiropyran, 8'-methoxy-N, 3,3-trimethylindolinobenzospiropyran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-7
-Methoxyfluoran, 3-diethylamino-6-benzyloxyfluoran, 1,2-benzo-6-diethylaminofluoran, 3,6-di-p-toluidino-4,
5-dimethylfluoran, phenylhydrazide-γ-lactam, 3-amino-5-methylfluoran and the like. These can be used alone or in combination of two or more. A variety of colors can be obtained by appropriately selecting a color-forming compound, so that multi-color support is possible.

The color developer used in the present invention includes phenols, phenol metal salts, carboxylic acid metal salts,
Examples include acidic compounds such as benzophenones, sulfonic acids, sulfonates, phosphoric acids, metal phosphates, acid phosphates, acid phosphate metal salts, phosphorous acid, and metal phosphites. These can be used alone or in combination of two or more.

The erasing agent used in the present invention preferably has good colorlessness when in the amorphous state. The more the erasing agent is amorphous and colorless and transparent, the more the paper can return to a state close to the original white paper when the color of the ink is erased. Since such properties are required, the erasing agent is preferably a compound having a large molecular weight, a small change in enthalpy of fusion ΔH of a crystal per weight, and a small maximum crystal growth rate MCV. If the change in enthalpy of melting ΔH of the crystal of the erasing agent is small, the amount of heat energy required for melting the crystal becomes small, which is also preferable from the viewpoint of energy saving. From the above viewpoints, a compound having a nearly spherical and bulky molecular skeleton such as a steroid skeleton is preferable as the erasing agent. In order to increase the solubility of the developer in the erasing agent, the erasing agent preferably has a high affinity for the developing agent, and for example, a compound having an alcoholic hydroxyl group is suitable. From the viewpoint of storage stability of the three-component system in the decolored state, the three-component system must have a glass transition point Tg of at least room temperature (25 ° C.),
It is preferable that the temperature is not lower than ° C. To satisfy this condition, the glass transition point of the erasing agent must be at least room temperature (25 ° C.).
As described above, the temperature is preferably 50 ° C. or higher. on the other hand,
The crystallization temperature of the erasing agent is in a temperature range between the glass transition point Tg and the melting point Tm of the ternary system. Therefore, in order to speed up the erasing, the glass transition point of the erasing agent is preferably 150 ° C. or lower. Preferred erasing agents satisfying these conditions include the following compounds (a) to (c).

(A) Sterol compound. Specific examples of the sterol compound include cholesterol, stigmasterol, pregnenolone, methylandrostenediol, estradiol benzoate, epiandrostene, stenolone, β-sitosterol, pregnenolone acetate, β-cholesterol, 5,16-pregnadien-3β -All-20-one, 5α-pregnene-3β-ol-20-one, 5-pregnene-3
β, 17-diol-20-one 21-acetate,
5-pregnene-3β, 17-diol-20-one
17-acetate, 5-pregnene-3β, 21-diol-20-one 21-acetate, 5-pregnene-3β, 17-diol diacetate, locogenin,
Tigogenin, esmilagenin, hecogenin, diosgenin and derivatives thereof. These erasing agents can be used alone or in combination of two or more.
Among these erasing agents, those suitable for obtaining a stable erased state include methylandrostenediol, hecogenin, locogenin, tigogenin, diosgenin, esmilagenin and the like.

When these erasing agents are used, when the ternary system in an amorphous state is heated to a temperature exceeding the glass transition point, the diffusion rate of the developer rapidly increases, and the direction of returning to the equilibrium state is increased. Then, the phase separation movement between the color developer and the erasing agent is accelerated. Then, when the three-component system is heated to a temperature equal to or higher than the crystallization temperature and lower than the melting point, and then gradually cooled to room temperature, the state becomes closer to the equilibrium state, becomes a stable phase separation state, and returns to the colored state. Therefore, the three-component system using the erasing agent (a) can in principle reversibly repeat the color-developed state and the decolored state.
In this sense, the erasing agent (a) may be hereinafter referred to as a “reversible erasing agent”. In fact, a rewritable recording medium utilizing such a reversible change has been proposed (for example, Japanese Patent Application No. 7-37001). However, the erasable inks of the present invention are intended for erasing printed inks and are not inherently reversible except for special applications.

(B) cholic acid, lithocholic acid, testosterone and cortisone, and derivatives thereof. Specific examples include cholic acid, cholic acid methyl ester, lithocholic acid, lithocholic acid methyl ester, hydroxycholic acid, hydroxycholic acid methyl ester, testosterone, methyltestosterone, 11α-hydroxymethyltestosterone, and hydrocortisone. Among them, those having two or more hydroxyl groups are particularly preferable.

The erasing agent (b) has a higher affinity with the color developer at the time of melting than the erasing agent (a) and has very high compatibility. In addition, since the erasing agent (b) has a high amorphous property,
Phase separation hardly occurs even after the component system is solidified. In this sense, the erasing agent of (b) may be hereinafter referred to as a "compatible erasing agent". Therefore, in the three-component system using the erasing agent (b), a more stable decolored state can be obtained.

(C) a 5- or more-membered non-aromatic cyclic compound having at least one hydroxyl group. The melting point of these compounds is preferably 50 ° C. or higher. Specific examples include alicyclic monohydric alcohols (eg, cyclododecanol), alicyclic dihydric alcohols (eg, 1,4-cyclohexanediol, 1,2-cyclohexanediol, 1,2-cyclododecanediol), saccharides And its derivatives (eg, glucose and saccharose) and alcohols having a cyclic structure (eg, 1,2,5,6-diisopropylidene-D-mannitol).

Although the erasing agent (c) may be used alone,
It is particularly effective when used together with the erasing agent (a). That is, the erasing agent of (c) has a strong affinity with the erasing agent of (a), and hardly causes phase separation even after solidification. In this sense, the erasing agent (c) may be hereinafter referred to as a “phase separation suppressing erasing agent” or a “phase separation suppressing agent”. Even when the erasing agent (c) is used, a more stable decolored state can be obtained.

Hereinafter, the specific structure and use of the erasable ink of the present invention will be described. One embodiment of the erasable ink of the present invention is obtained by dispersing an ink composition containing a color former, a color developer and an erasing agent in a color-forming state in a solvent.

The preferred compounding ratio of the coloring compound, the color developer and the erasing agent in the erasable ink is as follows. The mixing ratio of the color developer is preferably set to 0.1 to 10 parts by weight, more preferably 1 to 2 parts by weight, based on 1 part by weight of the coloring compound. When the amount of the color developer is less than 0.1 part by weight, the color development of the ink due to the interaction between the color former and the color developer becomes insufficient. When the amount of the developer exceeds 10 parts by weight, it is difficult to sufficiently reduce the interaction between the two. The compounding ratio of the erasing agent is preferably set to 1 to 200 parts by weight, more preferably 10 to 100 parts by weight, per 1 part by weight of the coloring compound. When the amount of the erasing agent is less than 1 part by weight, it is difficult to cause a state change between the color developing state and the color erasing state of the ink. When the erasing agent exceeds 200 parts by weight,
Insufficient color development of the ink.

Preferably, the solvent of the erasable ink is water. Although the ink composition may be dispersed in a solvent using a surfactant, it is preferable that the ink composition is microencapsulated and dispersed in the solvent. in this case,
In order to improve the weather resistance and the resistance to ultraviolet light of the ink, it is preferable to add an ultraviolet absorber to the ink composition in the microcapsule or to use an ultraviolet absorbing polymer as the shell of the microcapsule. The blending ratio of the polymer used for producing the microcapsules is 0.01 to 100 parts by weight per 1 part by weight of the erasing agent
Further, the content is preferably 0.1 to 5% by weight.

The concentration of the ink composition in the solvent varies depending on the application, but is preferably in the range of 0.1 to 10% by weight. If the concentration of the ink composition is less than 0.1% by weight, a sufficient print density cannot be obtained. If it exceeds 10% by weight, the viscosity of the ink becomes too high, which is particularly inconvenient when used as an ink for an ink jet printer. The ink composition dispersed in the solvent is preferably submicron-order particles that do not include particles of 10 μm or more.

The erasable ink of the present invention can be used as ordinary ballpoint pen and fountain pen ink, ink for printers such as ink jet printers, printing ink for screen printing and type printing, and printing on various papers. Can be. Further, in addition to paper, printing can be performed on a sheet for an overhead projector or the like. After printing, it can be easily erased only by heating.
That is, since the erasable ink contains an erasing agent that preferentially dissolves one of the color developing compound and the color developing agent at the time of melting, the solidified color developing compound and the color developing agent when solidified. The print can be almost completely erased without interaction, and the paper can be reclaimed in a blank state.
Therefore, since it is not necessary to use bleach or water for paper regeneration, the cost can be reduced and forest resources can be greatly contributed.

The erasable ink of the present invention does not necessarily require the reuse of paper, and can be applied to applications in which erasing can be simply performed after printing. For example, read a postcard's handwritten address with an image reader, convert it into barcode information, print a barcode with erasable ink, classify the postcard by machine in the office, sort it in the delivery order at another post office, and then heat it. Then, it can be used for the purpose of erasing a barcode. In this way, it is possible to keep no trace of processing on the delivered mail. Similarly, erasable inks can be applied to logistics in general. In this application, printing may be performed on a material other than paper.

Next, an apparatus for erasing the erasable ink and a printer using the erasable ink according to the present invention will be described. The apparatus for erasing the erasable ink and regenerating the paper according to the present invention may be in any form as long as it has a mechanism capable of heating and quenching. Specifically, a heating device having a heating resistor such as a thermal head may be used. A type of thermal head may use a heating resistor generally called a thermal bar, which can heat the paper over a wide area. In this case, the current supplied to the thermal bar may be controlled to return only a desired area of the paper to a blank sheet. If a heating device such as a heat roller is used, a large amount of paper can be reproduced by printing and erasing. Furthermore, in order to erase the print applied to the surface of a non-sheet-like article such as paper, the article may be heated by an infrared lamp or hot air, and may be cooled by blowing cold air or using a heat sink having a large heat capacity.

For example, as shown in FIG. 1, a thermal bar 13 adjusted to an appropriate area is provided between a pair of supply rollers 11, 11 and a pair of transport rollers 12, 12.
Pass the paper 10 that has been printed with erasable ink.
When an electric current is applied to the thermal bar 13, it can be instantly heated to 300 ° C. After the paper 10 is heated by the thermal bar 13,
As a result of the paper 10 being discharged from the apparatus and being rapidly cooled, the print on the paper 10 can be erased. FIG. 2 shows a manual erasing device (reproducing device) 21 incorporating the erasing mechanism of FIG.

FIG. 3 shows a mechanism for further ensuring erasure of printing and reproduction of paper as compared with FIG. This mechanism, in addition to the configuration of FIG. 1, includes a pair of rolling rollers 14, 14 for extending the wrinkles of the paper on the discharge side of the paper 10, and between the transport rollers 12, 12 and the rolling rollers 14, 14. U
A V light source 15 and a humidifier 16 are provided. In this mechanism, the dye can be completely decomposed by decomposing the pigment by the UV light source 15, and the paper 10 can be moderately humidified by the humidifying device 16 and then the wrinkles of the paper 10 can be extended by the rolling rollers 14, 14. it can. By using such a mechanism, the number of times paper is used can be increased. In the present invention, since the same paper is used many times, deterioration of the paper becomes a problem.
Considering this point, high-grade paper treated with plastic may be used as special paper.

As a printer using the erasable ink of the present invention, an ink jet printer is most suitable. In particular, when an ink containing a reversible erasing agent is used, a printer that can print by flying the ink into space without heating is desirable. Therefore, it is preferable that the optimal ink flying method uses the vibration of the piezo element or the ultrasonic wave.
If an ink containing the erasing agent of (b) or (c) is used, or if a material having a high Tg is used as all the ink components, a bubble jet printer that heats the ink can also be applied.

FIGS. 4A and 4B show an ink jet printer provided with the erasing mechanism shown in FIG. In the printer 31, printing paper is stored in a printing tray 32, and the paper is printed via a printing mechanism similar to a normal inkjet printer, and is discharged from a discharge port 33. Also, when playing back printed paper,
The paper 10 is inserted from the input port 34, and the supply roller 11, the transport roller 12, and the thermal bar 13 as shown in FIG.
And is collected in the collection tray 35 via the erasing mechanism provided with. In this case, the print tray 32 and the collection tray 35 have the same shape and can be replaced.

FIG. 5 shows an ink jet printer capable of printing on both new paper and printed paper. In the printer 41, a tray 42 for storing new paper is provided.
And the tray 43 for storing the printed paper
It is provided on one side. The tray 42 is also used as a tray for erasing printed paper and collecting recycled paper. New paper is discharged from the tray 42 after printing is performed by the printer head 45 via a printing mechanism of a normal inkjet printer. on the other hand,
The printed paper is conveyed from the tray 43 and is collected on the tray 42 after the printing is erased by the thermal bar 13, or is conveyed to the printer head 45 as it is and discharged after printing. The switching of the transport path of the reproduced paper is performed by the switching mechanism 44.

FIG. 6 shows an ink jet printer having a head for printing erasable ink and a head for printing normal ink. This printer 51
Are erasable ink head 52 and normal ink head 5
And 3. The instruction of the print information to the printer 51 is executed by executing an application on the computer 61,
This is performed by inputting, for example, an area corresponding to the fixed information area 62 and the variable information area 63 of the printing paper on the display. In the printer 51, the erasable ink head 52 and the normal ink head 53 perform printing on the paper 50 in a predetermined operation according to a print instruction from an application. With such a printer, it is possible to erase and rewrite only the variable information that has a possibility of being rewritten many times.

FIG. 7 shows an ink jet printer provided with an erasing mechanism including a heat roller. In the printer 71, the paper stored in the cassette 72 at the bottom is transported by a transport roller, printed by a printer head 73, and discharged from a discharge port 74. When the printed paper is to be reproduced, the paper is inserted through the input port 75, heated and erased by the heat roller 76, and discharged from the discharge port 77.

In the present invention, a composition containing a color-forming compound, a color developer, an erasing agent, a binder and the like is pulverized,
It may be used as a toner for electrophotography so that printing can be erased. In the case of electrophotography, since heating is performed to fix the toner transferred to the paper, it is preferable to use a compatible erasing agent or a phase separation suppressing erasing agent.

FIG. 8 shows an electrophotographic copying machine provided with an erasing mechanism comprising a heat roller. In this copying machine 81, paper is stored in a cassette 82 at the bottom.
A latent image is formed by irradiating light from an LED head 84 to a photosensitive drum 83 provided at the center of the apparatus.
The toner 86 charged by the developing device 85 is attached to the photosensitive drum 83 by using an electrostatic force to develop the latent image. The paper is transported by the transport roller at the same time as this, and the toner is transferred to the paper by passing between the photosensitive drum 83 and the transfer roller 87. The toner transferred to the paper is fixed by a fixing roller 88 and discharged from a discharge port 89. When the printed paper is to be reproduced, the paper is inserted through the input port 90, heated and erased by the heat roller 91, and discharged from the discharge port 92. The temperatures of the fixing roller 88 and the heat roller 91 are, for example, 1
The temperature of the heat roller 91 is set to a high temperature, such as 40 ° C. and 190 ° C.

Further, a printing toner containing a coloring compound and a developer and an erasing toner containing an erasing agent may be used. The ink component of the present invention can be applied to a thermal printer. In this case, a method of performing printing and erasing using a printing sheet (or ribbon) and an erasing sheet (or ribbon) is preferable. A sheet or ribbon made of a heat-resistant resin such as polyethylene terephthalate (PET) is used.

For example, a printing sheet is prepared by applying an ink composition containing a color former and a color developer on one sheet substrate. The ink composition may be applied together with a wax to facilitate transfer to paper. A composition containing an erasing agent is applied on another sheet substrate to prepare an erasing sheet. Then, using a thermal printer, the ink composition is thermally transferred to a medium using a printing sheet and printed, and if necessary, a composition containing an erasing agent in the medium on which the ink composition has been printed using the erasing sheet. Is thermally transferred and erased. As the erasing agent, it is preferable to use those classified as the above-described compatible erasing agent or phase separation suppressing erasing agent. At the time of erasing, the output of the thermal printer head is increased at a higher temperature than at the time of printing.

FIGS. 9A and 9B show examples of a printing sheet and an erasing sheet. 9A is a PET sheet on which a back coat layer 102 is formed.
A release layer 103, an ink layer 104, and a lubricant layer 105 are formed on a sheet 101. Note that the release layer 103 and the lubricant layer 105 are not necessarily provided. The erasing sheet 200 shown in FIG. 9B has a release layer 2 on a PET sheet 201 on which a back coat layer 202 is formed.
03, a barrier layer 204 and an erasing agent layer 205 are formed. By providing the barrier layer 204, it is possible to prevent the erasing agent from unnecessarily spreading on the print medium.
Note that the release layer 203 and the barrier layer 204 are not necessarily provided.

In this case, a color-developing ink composition containing a color developing compound, a color developer and a reversible erasing agent having a relatively low glass transition point may be used. When such an ink composition is thermally transferred and printed on paper, the print is temporarily erased by heating, and when left at room temperature, the print can be returned to the original state. As an application that uses such a function, for example, a label printed with a warning message is attached to fresh food that needs to be kept refrigerated, so that the warning message appears on the label when left at room temperature. It is possible to do.

Further, when the ink composition is made to have reversibility as described above, the color separation compound and the color developer are promoted to phase-separate from the reversible erasing agent in order to increase the color development speed of printing. A compound (phase separation accelerator) may be added. As the phase separation accelerator, a highly crystalline low molecular weight organic material having a long straight chain portion having 8 or more carbon atoms and a polar group such as, for example, OH, CO, and COOH is preferable. For example, a linear higher alcohol having a long linear alkyl group, a linear higher polyhydric alcohol, a linear higher fatty acid, a linear higher polyhydric fatty acid,
Examples thereof include esters and ether conjugates thereof, linear higher fatty acid amides, and linear higher polyvalent fatty acid amides.

More specifically, 1-docosanol, 1-docosanol,
Linear higher monohydric alcohols represented by tetracosanol, 1-hexacosanol, 1-octacosanol and the like;
Linear higher polyhydric alcohols represented by 1,12-dodecanediol, 1,12-octadecanediol, 1,2-tetradecanediol, 1,2-hexadecanediol, etc .; behenic acid, 1-docosanoic acid, 1-tetracosane Linear higher fatty acids such as acids, 1-hexacosanoic acid and 1-octacosanoic acid; linear higher polyvalent fatty acids such as dodecanedioic acid and 1,12-dodecanedicarboxylic acid; stearone and the like. Linear higher ketones
Straight-chain higher fatty acid alcohol amides such as isopropanolamide stearate, isopropanolamide behenate, and hexanole behenate; straight-chain higher fatty acids such as diester ethylene glycol laurate, catechol laurate diester, and cyclohexanediol laurate diester Fatty acid diol diester. These can be used alone or in combination of two or more. Examples of the mixture include ester wax, alcohol wax, and urethane wax, which can be used as a phase separation accelerator.

The components applied to the printing sheet and the components applied to the erasing sheet may be different from those described above.
For example, a printing sheet coated with an ink composition containing a color former, a color developer and a phase separation suppressing erasing agent (or a compatible erasing agent), and an erasing sheet coated with a composition containing a reversible erasing agent A sheet may be used. Also, a coloring compound,
Printing by applying an ink composition containing a developer, a reversible erasing agent, and a phase separation suppressing erasing agent (or a compatible erasing agent), wherein the reversible erasing agent and the phase separation suppressing erasing agent are phase-separated. May be used alone.

It is also possible to use two types of printing methods in combination.
For example, the image may be printed on paper by electrophotography using a toner containing a color former and a developer, and the erasing agent may be thermally transferred from the erasing sheet to the printed paper for erasure.

Further, printing and erasing may be performed as follows. At the time of printing, the toner is transferred to a heat-resistant sheet by electrophotography using a toner containing a color former and a developer, and the toner is thermally transferred from the heat-resistant sheet to paper for printing. At the time of erasing, the toner is transferred to a heat-resistant sheet by electrophotography using a toner containing an erasing agent, and the toner is thermally transferred from the heat-resistant sheet to a printed paper for erasing. Also in this case, erasing is performed at a higher temperature than printing. In this way, a partial modification of the printing is possible. Also, in normal electrophotography, the entire surface of the paper is heated in the fixing process, so after erasing part of the paper and reprinting, erasing the printing of another part, the reprinted part is erased in the fixing process May be done. On the other hand, in the above method, it is not necessary to perform the fixing step, so that the correction can be performed two or more times.

[0047]

Embodiments of the present invention will be described below. Example 1 1 part by weight of crystal violet lactone (CVL) as a color-forming compound, 2 parts by weight of 2,4,4'-trihydroxybenzophenone as a developer, and 10 parts by weight of methylandrostenediol as an erasing agent were dissolved in toluene / After uniformly mixing using a cyclohexane mixed solvent,
The solvent was evaporated to obtain a powder. After heating this powder to 150 ° C., it was cooled to room temperature over 10 minutes to give a blue color. 1 g of this powder was added to 50 cc of water to which 0.5 g of sodium stearate was added as a surfactant.
And the ink composition was pulverized to a micron order with a pulverizer to prepare an dispersed ink.

Using this ink, letters were written on A4 size paper with a pen. After drying, a thermal bar set at 200 ° C. was moved over the paper for 2 seconds. As a result,
The letters disappeared completely and a blank sheet was obtained. It was confirmed that even when the recording and erasing of characters were repeated 30 times in the same manner as described above, a blank sheet was finally obtained. The optical density (OD) of the finally obtained white paper was 0.15.

Example 2 Using 1 part by weight of ETAC as a color former, 1 part by weight of 2,4,4'-trihydroxybenzophenone as a color developer, and 5 parts by weight of hecogenin as an erasing agent, using a mixed solvent of toluene / cyclohexane. After mixing evenly,
The solvent was evaporated to obtain a powder. After heating this powder to 150 ° C., it was cooled to room temperature over 10 minutes to give a blue color. 1 g of this powder was put into 50 cc of water to which 0.5 g of sodium stearate had been added, and crushed and dispersed to a micron order by a crusher to prepare an ink.

This ink was used as an ink for an ink jet printer (MJ800C manufactured by Epson Corporation) using a piezo element, and was printed on A4 size paper. Thereafter, the print was erased by passing a thermal bar over the paper. When the recycled paper was stored at 60 ° C. for 30 hours, the print information was not displayed again and the storage stability was good. After printing again, light of 5000 lux was irradiated for 300 hours. In this case, the decrease in print density was 10% or less.

Example 3 PSD-HR (manufactured by Nippon Soda Co., Ltd.) as a coloring compound
1 part by weight, 1 part by weight of α, α, α′-tris (4-hydroxyphenyl) -1-ethyl-4-isopropylbenzene as a developer, and pregnenolone 2 as an erasing agent
After melting and mixing 0 parts by weight, the mixture was slowly cooled to obtain a red solid. Using a ball mill, this solid was crushed and dispersed to an order of 10 μm in an aqueous 8 wt% gum arabic solution. Next, an aqueous gelatin solution was mixed at 40 ° C., and the mixture was stirred for 1 hour, and then water was added dropwise, followed by dilution by stirring. Subsequently, the pH of the solution was adjusted to 3.9 by adding a 10 wt% acetic acid aqueous solution, and the pH of the solution was further adjusted to 7.0 by adding 37% formalin. The liquid was cooled to 5 ° C., left at room temperature for 3 days, and then microcapsules formed in the liquid were separated by a centrifugal separator to prepare red microcapsules. The microcapsules were dispersed in water at a concentration of 8% by weight to prepare an ink.

This ink was used as an ink for an ink jet printer (MJ800C manufactured by Epson Corporation) using a piezo element and printed on A4 size paper. Thereafter, the print was erased by passing a thermal bar over the paper. When the recycled paper was stored at 60 ° C. for 30 hours, the print information was not displayed again and the storage stability was good. After printing again, light of 5000 lux was irradiated for 300 hours. In this case, the decrease in print density was 10% or less.

Example 4 Microcapsules obtained in the same manner as in Example 3
It was dispersed in water at a concentration of 5 wt% to prepare a letterpress printing ink.

Using this ink, A4
Printed on size paper. Thereafter, the print was erased by contacting a 200 ° C. heat roller for 2 seconds. It was confirmed that even when printing and erasing were repeated 30 times in the same manner as described above, a blank sheet was finally obtained. The optical density (OD) of the finally obtained white paper was 0.15.

Example 5 1 part by weight of crystal violet lactone (CVL) was used as a coloring compound, 2 parts by weight of 2,4,4'-trihydroxybenzophenone was used as a color developer, and 20 parts by weight of pregnenolone was used as an erasing agent. Except for the above, an ink was prepared by dispersing the microcapsules in water at a concentration of 8% by weight in the same manner as in Example 3.

This ink was used as an ink for an ink jet printer (MJ800C manufactured by Epson Corporation) using a piezo element, and was printed on A4 size white paper. Thereafter, the print was erased by passing a thermal bar over the paper. When the recycled paper was stored at 60 ° C. for 30 hours, the print information was not displayed again and the storage stability was good. After printing again, light of 5000 lux was irradiated for 300 hours. In this case, the decrease in print density was 10% or less.

Example 6 As a coloring compound, PSD-150 (manufactured by Nippon Soda Co., Ltd.)
2 parts by weight of a composition formed by mixing 2,3,4,4'-tetrahydroxybenzophenone in a ratio of 1: 1 as a developer, 7 parts by weight of D-glucose as an erasing agent, and 3 parts by weight of gelatin as a binder Parts and a small amount of isopropyl alcohol and an antifungal agent were added to water, and a solid content of 10 parts was added.
% Aqueous ink was prepared. This ink was black.

The ink was printed on paper by an ink jet printer and dried. By heating this paper with a thermal printer head (TPH) at a power of 0.35 mJ / dot or more, printing could be erased. This erased state did not change at 40 ° C. for 1000 hours.

Examples 7 to 11 4.5 μm PE back-coated with a thermosetting silicone acrylic resin as a sheet substrate to a thickness of about 0.2 μm.
Using a T film, a printing sheet and an erasing sheet were prepared. Printing and erasing were performed at a recording speed of 10 ms / L using a thermal printer head having a pixel density of 8 dots / mm.

Example 7 1 part by weight of crystal violet lactone (CVL) as a color-forming compound and propyl gallate 1 as a color developer
Parts by weight, 15 parts by weight of rice wax as a hot-melt transfer agent, and 3 parts by weight of polystyrene as a binder resin, and heat-fused to form an ink composition, which is applied to a surface of a sheet substrate with a bar coater to a thickness of about 2 μm. Thus, a printing sheet was prepared.

1 part by weight of 1,2-cyclohexanediol as an erasing agent and 1 part by weight of methyl cholate were mixed and melted by heat, and about 3 parts were coated on the surface of another sheet substrate with a bar coater.
It was applied to a thickness of μm to prepare an erasing sheet.

FIG. 10 shows the result of examining the reflection density of printing when printing, erasing, and reprinting were performed by changing the power of TPH as described below. When a printing sheet was overlaid on paper and thermally transferred using TPH, it was 0.15 mJ /
Printing could be performed stably with a power of more than dot.

When an erasing sheet was overlaid on this paper and thermally transferred using TPH, erasing could be performed with a power of 0.3 mJ / dot or more. This erased state was maintained even after 300 hours at 40 ° C.

The printing sheet is again placed on this paper, and TPH
When thermal transfer was carried out using 0.1 to 0.2 mJ / d
Reprinting was possible with the power of ot. But the power is 0.3
When it was increased to mJ / dot or more, printing could not be performed.

Example 8 1 part by weight of CVL as a coloring compound and 2, as a color developer
1 part by weight of 4,4'-trihydroxybenzophenone, 5 parts by weight of methylandrostenediol as a reversible erasing agent, 5 parts by weight of 1-docosanol as a phase separation accelerator, and 3 parts by weight of a styrene-methacrylic acid copolymer as a binder Was melted to form an ink composition, and applied to a surface of a sheet substrate with a bar coater to a thickness of 2 μm to prepare a printing sheet. The erasing sheet was produced in the same manner as in Example 7.

FIG. 11 shows the results of examining the reflection density of a print when printing, reversible erasure, complete erasure, and reprinting were performed by changing the power of the TPH as described below. When a printing sheet is overlaid on paper and thermally transferred by TPH,
Stable printing was possible with a power of 0.15 mJ / dot or more.

When the printed portion of this paper was heated by TPH, it could be erased at 0.35 mJ / dot or more. When the paper was left at room temperature, the printed characters returned to the original state after 72 hours.

When an erasing sheet was overlaid on this paper and thermally transferred by TPH, erasing could be performed with a power of 0.35 mJ / dot or more. This erased state did not change even after elapse of 1000 hours at 60 ° C.

The printing sheet is again placed on this paper, and TPH
0.15 to 0.25 mJ / d
Reprinting was possible with the power of ot. But the power is 0.3
When it was increased to 5 mJ / dot or more, printing could not be performed.

Example 9 1 part by weight of ETAC (manufactured by Yamada Chemical Co., Ltd.) as a coloring compound, 1 part by weight of 2,4,4'-trihydroxybenzophenone as a color developer, and 5 parts by weight of methyl lithocholic acid as a compatible erasing agent Parts, 3 parts by weight of polystyrene as a binder, dispersed at a temperature at which methyl lithocholic acid does not melt to form an ink composition, and applied to a surface of a sheet substrate with a bar coater to a thickness of 2 μm to prepare a printing sheet. did.

Β-sitosterol as a reversible erasing agent,
Rice alcohol as a phase separation accelerator was mixed at a weight ratio of 2: 1 and melted by heat, and applied to the surface of another sheet substrate with a bar coater to a thickness of 2 μm to prepare an erasing sheet.

FIG. 12 shows the result of examining the reflection density of printing when printing, erasing, and reprinting were performed by changing the power of the TPH as described below. When a printing sheet was overlaid on paper and thermally transferred by TPH, it was 0.10 mJ / d.
Printing was stably performed with a power of over ot. The printed portion of the paper was heated by TPH but could not be erased.

When an erasing sheet was superimposed on this paper and thermally transferred by TPH, erasing was performed with a power of 0.3 mJ / dot or more. This erased state did not change even after elapse of 300 hours at 40 ° C.

A printing sheet is again placed on this paper, and TPH
0.15 to 0.2 mJ / do
Reprinting was possible with the power of t. However, the power is 0.3m
If it was increased to J / dot or more, printing could not be performed.

Example 10 1 part by weight of RED40 (manufactured by Yamada Chemical Co., Ltd.) as a coloring compound, 1 part by weight of 2,3,4,4'-tetrahydroxybenzophenone as a color developing agent, and as a phase separation suppressing erasing agent After melt-mixing 10 parts by weight of 1,2-cyclohexanediol, the mixture was pulverized to 10 μm or less.

On the other hand, 1 part by weight of RED40 (manufactured by Yamada Chemical Co., Ltd.) as a coloring compound and 2, 3, 4, 4 ′ as a color developer
1 part by weight of tetrahydroxybenzophenone and 10 parts by weight of cholesterol as a reversible erasing agent were melt-mixed and then pulverized to 10 μm or less.

These two powders were mixed at a weight ratio of 1: 1 and dispersed in a 5% aqueous gelatin solution so as to have a solid content of 20% to prepare an ink. This ink was applied to the surface of the sheet substrate with a bar coater so as to be about 3 g / m ² to prepare a printing sheet. In this embodiment, no erasing sheet is used.

FIG. 13 shows the relationship between TPH power and reflection density. When a printing sheet was overlaid on paper and thermally transferred by TPH, printing was possible with a power of 0.10 to 0.3 mJ / dot. However, printing was not possible with a power exceeding 0.3 mJ / dot.

The printed portion of this paper was adjusted to 0.10 by TPH.
Even when heating was performed with a power of about 0.3 mJ / dot, erasing could not be performed. However, erasing was possible with a power of 0.3 mJ / dot or more. This erased state is
There was no change even after the lapse of 00 hours.

Example 11 Using a composition prepared by heating and melting 1 part by weight of CVL as a coloring compound, 1 part by weight of propyl gallate as a color developer, and 10 parts by weight of cholesterol as a reversible erasing agent,
Gelatin capsule microcapsules were prepared. One part by weight of rice wax as a hot-melt transfer agent was mixed with 3 parts by weight of the microcapsules, and the mixture was applied to a sheet substrate with a hot melt coater to prepare a printing sheet.

The sheet for printing was superimposed on paper and thermally transferred by TPH under the condition of 0.15 mJ / dot, so that the characters “improper storage” were printed. The paper was heated to 160 ° C. to temporarily erase the characters.

When this paper was stored in a refrigerator,
No letters appeared even after 240 hours at 10 ° C.
However, when left in a room at 25 ° C., the printed characters returned to their original state after 10 hours. Further, when left in a room at 30 ° C., the printed characters returned to the original state after 2 hours. As described above, the ink of the present invention functions as a heat history sensor, and can be applied to uses such as quality control of fresh food.

The temperature at which printing returns to its original state after printing and temporarily erasing the ink of the present invention can be controlled by selecting a material having an appropriate glass transition point. Table 1 shows the glass transition points and melting points of typical reversible erasing agents. The coloring speed of the ink near the above-mentioned temperature can be controlled by adding a phase separation accelerator or selecting an appropriate color developer.

[0084]

[Table 1]

Example 12 1 part by weight of CVL as a coloring compound, 1 part by weight of propyl gallate as a color developer, 10 parts by weight of cholesterol as a reversible eraser, and rice wax 3 as a hot-melt transfer material
Parts by weight, 5 parts by weight of polystyrene as a binder, and a small amount of a hydrophobized ultrafine quartz filler and a charge controlling agent, which are then solidified and pulverized.
Finely pulverized to 0 μm to prepare a toner. An erasing sheet was produced in the same manner as in Example 7.

This toner is used as a copy machine (Canon, FC
210), and the characters were copied on paper, and could be fixed stably. When an erasing sheet was stacked on this paper and thermally transferred by TPH, erasing could be performed with a power of 0.3 mJ / dot or more. This erase state is 300 ° C. at 40 ° C.
There was no change over time.

Example 13 1 part by weight of ETAC (manufactured by Yamada Chemical Co., Ltd.) as a coloring compound, 1 part by weight of 2,4,4'-trihydroxybenzophenone as a developer, 5 parts by weight of hecogenin as a reversible erasing agent, 3 parts by weight of rice alcohol (a mixture containing a large amount of myricyl alcohol) as a phase separation accelerator, 5 parts by weight of a styrene-methacrylic acid copolymer as a binder, and a small amount of a small amount of a hydrophobized ultrafine quartz filler and a charge controlling agent are thermally melted. After that, it is solidified and pulverized.
Finely pulverized to 0 μm to prepare a toner. An erasing sheet was produced in the same manner as in Example 7.

This toner is used in a copying machine (Canon, FC
210), and the characters were copied on paper, and could be fixed stably. When the printed portion of this paper was heated with TPH at a power of 0.35 mJ / dot or more,
Temporarily erased. The erased characters were stable at room temperature. It returned to its original state after 3 weeks at 40 ° C. At 135 ° C., it returned to its original state in 0.2 seconds.

When an erasing sheet was overlaid on this paper and thermally transferred by TPH, erasing could be performed with a power of 0.35 mJ / dot or more. This erased state did not change even after elapse of 1000 hours at 60 ° C.

[0090]

As described above in detail, according to the present invention, it is possible to provide an ink which can be printed with a sufficient contrast and can be erased by heat, and can reuse paper.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an erasing mechanism for erasing a print using the erasable ink of the present invention.

FIG. 2 is a perspective view of an erasing device for erasing printing using erasable ink according to the present invention.

FIG. 3 is a schematic diagram of another erasing mechanism for erasing printing with the erasable ink of the present invention.

FIG. 4 is a perspective view of the inkjet printer of the present invention and a schematic diagram of an erasing mechanism thereof.

FIG. 5 is a schematic view of another ink jet printer of the present invention.

FIG. 6 is a perspective view of still another ink jet printer of the present invention.

FIG. 7 is a diagram showing a configuration of still another inkjet printer of the present invention.

FIG. 8 is a diagram showing a configuration of an electrophotographic copying machine of the present invention.

FIG. 9 is a cross-sectional view of a sheet coated with the ink of the present invention and a sheet coated with the erasing agent of the present invention.

FIG. 10 is a diagram showing a relationship between printing power and reflection density in Embodiment 7 of the present invention.

FIG. 11 is a diagram showing a relationship between printing power and reflection density in Embodiment 8 of the present invention.

FIG. 12 is a diagram showing the relationship between printing power and reflection density in Embodiment 9 of the present invention.

FIG. 13 is a diagram showing the relationship between print power and reflection density in Embodiment 10 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Paper 11 ... Supply roller 12 ... Conveyance roller 13 ... Thermal bar 21 ... Manual erasing apparatus (reproduction apparatus) 14 ... Rolling roller 15 ... UV light source 16 ... Humidifier 31 ... Printer 32 ... Printing tray 33 ... Discharge port 34 ... Insertion port 35. Collection tray 41. Printers 42 and 43. Tray 44. Switching mechanism 45. Printer head 50. Paper 51. Printer 52. Erasable ink head 53. Normal ink head 61. Computer 62. Fixed information area. 63: Variable information area 71: Printer 72: Cassette 73: Printer head 74: Discharge port 75: Input port 76: Heat roller 77: Discharge port 81: Copy machine 82: Cassette 83: Photosensitive drum 84: LED head 85: Developing device 86: toner 87: transfer roller 88: Attaching roller 89 ... Discharge port 90 ... Input port 91 ... Heat roller 92 ... Discharge port 100 ... Printing sheet 101 ... PET sheet 102 ... Back coat layer 103 ... Release layer 104 ... Ink layer 105 ... Lubricant layer 200 ... Erase sheet 201: PET sheet 202: Back coat layer 203: Release layer 204: Barrier layer 205: Eraser layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI-B41M 5/18 101C (72) Inventor Sawako Fujioka 1 Kosuka-Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba R & D Center ( 72) Inventor Tetsuo Okuyama 1 Toshiba R & D Center, Komukai, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture (56) References JP-A-50-81157 (JP, A) JP-A-61-53388 (JP, A) JP-A-4-314584 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 11/00-11/20 B41M 5/26

Claims (11)

(57) [Claims] Claims: 1. A color forming compound which is in a colored state upon interaction
Selected from substances and developers and sterol compounds
An ink composition comprising: an ink composition comprising: 2. A color forming compound which is in a colored state upon interaction.
Substances and developer and cholic acid, lithocholic acid, test
Consisting of Ron and cortisone and their derivatives
An ink composition containing an erasing agent selected from the group,
Erasable ink characterized by being dispersed in a solvent . 3. 0.1 part by weight of the coloring compound is 0.1 part by weight.
Claims: 10 to 10 parts by weight of a developer
Item 3. The erasable ink according to item 1 or 2 . 4. 1-2 parts per 1 part by weight of the coloring compound.
Claims: 100 parts by weight of an erasing agent
3. The erasable ink according to 1 or 2 . 5. 請, wherein the solvent is water
3. The erasable ink according to claim 1 or 2 . 6. The coloring compound, a color developer and an erasing agent.
Is microencapsulated and separated into solvents.
Erasable ink according to claim 1 or 2, characterized in that is dispersed. 7. The method according to claim 1, wherein the concentration of the ink composition in the solvent is
2. The composition according to claim 1, wherein the content is 0.1 to 10% by weight.
Or the erasable ink according to 2 . 8. A printer comprising a printing mechanism for printing erasable ink according to claim 1 and a printing mechanism for printing normal ink. 9. The printer according to claim 8 , wherein the printing mechanism is an ink jet printer head. 10. The printer according to claim 8, further comprising a mechanism for heating and erasing the printed erasable ink. 11. The printer according to claim 10 , wherein said erasing mechanism is a thermal bar.