JP2000127358A - Latent image printing method using ink-jet recording method, and anytime available developing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a method for easily forming a transparent image on a paper, using a colorless transparent liquid and reproducing an image as needed in the conventional ink-jet recording system, which cannot use an ink and a treating liquid for insolubilizing or aggregating a coloring agent of the ink. SOLUTION: A colorless transparent latent image to be visualized by a post treatment is formed on a medium to be recorded by printing a colorless transparent liquid on the medium to be recorded in an ink-jet recording apparatus. The apparatus comprises the means for forming the colorless transparent latent image, and a means for reproducing the image by a post treatment of the medium to be recorded with the latent image formed with the colorless transparent liquid, in particular, by producing a difference between the surface pH of the medium to be recorded and the transparent ink image pH on the medium to be recorded by applying an ink containing a substance to have a color change according to the pH change, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of printing a colorless and transparent image in an ink jet recording apparatus and then separately forming a color, and particularly to a method in which a color-changing substance is discolored on a recording medium on which an image is formed with a colorless and transparent liquid. The present invention relates to a latent image printing method using an ink jet recording method constituted by means for developing an image formed of a colorless and transparent liquid on a recording medium by applying ink, and a development method that can be used at any time.

[0002]

2. Description of the Related Art As a method of forming a transparent image on paper using a colorless and transparent liquid and reproducing the image when necessary, a transparent image is formed by juice of citrus fruits and the like, followed by heating. A so-called brushing method for visualizing brown to black images from colorless paper is generally widely known.

[0003] If this bleeding is to be carried out by an ink jet method, it is necessary to incorporate organic acids, which are substances causing color development upon heating, into the ink, and there has been a problem that the organic acids attack ink tanks and head members.
As a solution to this problem, Japanese Patent Application Laid-Open No. 9-254415 discloses a processing liquid for insolubilizing or aggregating the ink and the colorant of the ink by using an ink and a processing liquid for insolubilizing or aggregating the coloring material of the ink. An ink jet recording method is disclosed.

[0004]

However, in the ink jet recording method for insolubilizing or aggregating the ink and the colorant of the ink, the ink jet recording method described above can be applied only to an ink jet recording apparatus equipped with a processing liquid for insolubilizing or agglomerating the ink. There was a problem that it was not possible to start the game.

According to the present invention, a transparent image can be easily formed on a paper surface using a colorless and transparent liquid even in a conventional ink jet recording system in which an ink and a processing liquid for insolubilizing or aggregating a colorant of the ink cannot be used. In other words, it is necessary to realize a method of reproducing an image at a proper time.

[0006]

The present invention for achieving the above object is as follows.

This is a method of printing a colorless and transparent liquid on a recording medium in an ink jet recording apparatus to form a colorless and transparent latent image which can be visualized by post-processing on the recording medium. A latent image forming / developing method comprising: a latent image forming unit; and a unit for visualizing the latent image by post-processing of the recording medium on which the latent image is formed with the colorless transparent liquid. Further, the means for visualizing the colorless and transparent latent image is a means for forming the colorless and transparent image on the recording medium by printing the colorless and transparent liquid on the recording medium, and an image with the colorless and transparent liquid. This is a means for applying an ink containing a substance that changes color by a change in pH to the formed recording medium to express an image by a difference between the surface pH of the recording medium and the pH of the transparent ink image on the recording medium. , Latent image printing and optional development.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to preferred embodiments of the present invention.

The colorless and transparent ink of the present invention can form a colorless and transparent recorded image, that is, a latent image by printing on a recording medium, and visualize the latent image by post-processing. In the present invention, the “colorless and transparent” of the liquid and the image means that the presence or absence of the printing on the recording medium and the contents thereof cannot be identified unless a special operation is performed after the printing, and the liquid before the printing is used. It may be slightly colored or slightly cloudy.

[0010] As a method of visualizing the latent image, an ink containing a substance that changes color by a change in pH is applied to the recording medium to thereby adjust the surface pH of the recording medium and the pH of the transparent ink image on the recording medium. A method in which an image is expressed by the difference in color, a method in which the colorless transparent ink itself is denatured and colored by ultraviolet light of a specific wavelength, etc., or a reactive gas substance not present in the normal atmosphere is sprayed or a recording medium is exposed to the gas. A chemical reaction with the transparent ink to form a color.

Among them, a method of applying an ink containing a substance that changes color by a change in pH is simple and preferable. In this case, the colorless transparent ink to be printed depends on the pH of the recording medium.
The purpose of the present invention is to change the pH at the place where the colorless and transparent liquid is printed.

For this purpose, a non-volatile or low-volatility liquid is used in a colorless and transparent liquid so that the desired pH can be maintained on the recording medium even after the water in the liquid has evaporated after printing on the recording medium. It must contain a basic or acidic substance.

The recording medium used in the present invention is preferably printed on plain paper used in general offices and the like.

The water-soluble organic solvent used for the colorless and transparent liquid is preferably a water-soluble organic solvent generally used as an ink for ink jet recording.

The colorless and transparent ink of the present invention may contain, if necessary, a surfactant, a rust inhibitor, a preservative, a fungicide, an antioxidant, an antioxidant, an evaporation promoter, Various additives such as a water-soluble polymer may be contained.

As the pH coloring indicator contained in the ink of the present invention containing a substance that changes color by changing pH, a compound that changes color, develops color, or loses color depending on the pH of a colorless and transparent liquid is used. Common examples of such dyes include, for example, pentamethoxy red, quinaldine red, 2,4-
Dinitrophenol, hexamethoxy red, heptamethoxy red, quinoline blue, o-cresolphthalein, thymolphthalein, phenolphthalein, methyl orange, congo red, salicylic acid, α-naphthylamine, 3,6-dihydroxyphthalic acid, m- Acid and alkali indicators such as cresol purple, thymol blue, dimethyl yellow, bromophenol blue, bromocresol green, methyl red, chlorophenol red, bromocresol purple, bromothymol blue, neutral red, phenol red, cresol red, thymol blue, etc. can give.

The coloring mechanism of these compounds is often
A change in pH causes the addition or elimination of a proton to or from a color-forming structural portion in the molecule, resulting in reversible color change. For example, in a hydroxyazo dye,
Proton is eliminated from the OH reactive group and has a large electron donating property
-O ^- When changing the electronic state of the electron resonance structure portion of the azo group changes, it showed significant spectral changes, it is known that discoloration occurs. Of course, in the present invention, p
As long as the compound changes color, loses color, or develops color due to the fluctuation of H, it is possible to use compounds other than those described above.

An image developed by coloring or discoloration may be obtained by placing the developed dye under non-coloring conditions, and / or by dissolving the developed dye itself.
A method of applying a decoloring solution containing a substance containing water and a water-soluble organic solvent as main components and the pH of which is decolorized by a pH change or returned to its original color by a color change, or a substance which changes color or develops a color by a pH change Can be erased by applying a decoloring liquid containing a chemical that dissolves and dissolves the ink containing, and the recording medium from which the image has been erased can be reused for normal printing.
In addition, a method of placing the developed dye under non-coloring conditions,
When both the method of separating and dissolving the colored dye itself are used in combination, for example, when a decoloring liquid that combines both pH change and ink color component decomposition is used, the process is repeated for latent image printing and occasional development. Available.

In the present invention, as a means for applying an ink containing a substance that changes color by a change in pH onto a recording medium on which an image is formed with a colorless and transparent liquid, a spray, a brush, a brush, or the like is used. An application method is also conceivable. However, when using a spray, a brush, a brush, or the like, it is difficult to control the amount of ink containing a substance that changes color due to a change in pH. There is a problem that it takes time and a problem that the printed matter is curled or cockled after drying and cannot be stored neatly. Therefore, in the present invention, as a means for applying an ink containing a substance that changes color by a change in pH onto a recording medium on which an image is formed with a colorless and transparent liquid, a writing instrument for supplying ink from the inside, especially an optimal amount, can be easily prepared. It is characterized in that it is applied by a felt pen which can be applied.

[0020]

Next, the present invention will be described in more detail with reference to examples.

Example Preparation of Colorless Transparent Ink Glycerin 7 parts Ethylene glycol 7 parts Sodium hydroxide 0.7 part Ammonium sulfate 2.5 parts Water balance The colorless transparent ink used in this example is a non-volatile acid substance or It contains a basic substance and water, a water-soluble organic solvent and other components such as a viscosity adjuster, a pH adjuster, a preservative, a surfactant and an antioxidant as required.

Preparation of Ink Containing Substance that Colors Due to pH Change Glycerin 30 parts Ethanol 40 parts Bromothymol blue 0.4 part Water balance The above composition yielded an orange-yellow ink.

The colorless and transparent ink used in the present embodiment is composed of a substance which changes its color due to a change in pH, water, a water-soluble organic solvent and other components such as a viscosity adjuster, a pH adjuster,
Preservatives, surfactants and antioxidants are included as needed.

As a recording device used for printing the adjusted transparent ink, a commercially available BJC-400J color cartridge is used by filling the black tank of a BJC-400J color cartridge using (trade name: BJC-400J manufactured by Canon Inc.). Printing was performed on plain paper (trade name: Canon PB paper) to create a colorless and transparent recorded image.

As a method for applying an ink containing a substance which changes color by a pH change adjusted in this embodiment to a colorless and transparent recorded image, a felt pen (trade name: PROPUS)
EYE fluorescent marker pen (manufactured by Mitsubishi Pencil) was extracted, and then filled with the ink prepared above.

[Comparative Example] As a comparative example, a transparent ink was prepared by removing sodium hydroxide and ammonium sulfate from the colorless transparent ink used in the above example, and a colorless transparent image was formed under the same conditions as in the example. And pH
An ink containing a substance that changed color by the change was applied by the felt pen.

[Evaluation Method] The evaluation method was as follows. The color cartridges of Examples and Comparative Examples were filled in a black tank of a BJC-400J color cartridge, and the ink cartridge was filled with BJC-400J.
A colorless and transparent recording image was created by mounting a 400J main body and printing a monochrome image on commercially available plain paper (trade name: Canon PB paper).

Next, the colorless and transparent recorded image created by the above method is traced with a felt pen filled with an ink containing a substance which changes its color by a change in pH. An ink containing a discoloring substance was applied, and it was confirmed whether a colorless and transparent recorded image appeared.

[Results] In the examples, when an ink containing a substance discolored by a change in pH was applied to a colorless and transparent image formed with a transparent ink using a felt pen, printing was performed with the transparent ink. A colorless and transparent image could be reproduced by changing the color of the portion from yellow to blue.

In the comparative example, when an ink containing a substance that changes its color due to a change in pH was applied to a colorless and transparent image made of a transparent ink with a felt pen, discoloration of the portion printed with the transparent ink was recognized. Did not.

[0031]

A method for forming a colorless and transparent latent image which can be visualized by post-processing on a recording medium by printing a colorless and transparent liquid on the recording medium in an ink jet recording apparatus, especially on a recording medium A method for printing a colorless transparent liquid having a different pH from the above, and means for visualizing the latent image by post-processing on a recording medium formed with the colorless transparent liquid by post-processing, particularly a substance which changes color or develops color due to a change in pH Latent image printing / optional development method comprising means for expressing an image by applying a difference between the surface pH of the recording medium and the pH of the image drawn by the transparent liquid on the recording medium by applying ink containing By using a colorless and transparent liquid, a transparent image can be easily formed on a sheet of paper, and the image can be reproduced when necessary.

Continued on front page F-term (reference) 2C056 FC01 FD05 FD20 2H086 BA01 BA02 BA05 BA52 BA53 BA56 BA59 BA60 4J039 BA14 BA18 BA29 BC07 BC10 BC33 BC47 BE02 BE04 BE05 BE06 BE30 CA02 EA29 GA24 GA26

Claims (15)

[Claims] 1. A method for forming a colorless and transparent latent image which can be visualized by post-processing on a recording medium by printing a colorless and transparent liquid on the recording medium in an ink jet recording apparatus. 2. A means for forming a colorless and transparent latent image according to claim 1, and means for visualizing the latent image by post-processing of a recording medium on which an image has been formed with the colorless and transparent liquid. Latent image printing and occasional development method. 3. The latent image printing / optional development method according to claim 2, wherein the colorless and transparent liquid according to claim 1 itself contains a dye precursor that develops color by the post-processing. 4. The colorless and transparent liquid according to claim 1 does not contain a dye precursor, and the post-processing is a means for applying an ink containing a dye precursor, and the ink is a colorless and transparent liquid. The latent image printing / optional development method according to claim 2, wherein the color is formed by the action of a liquid component. 5. The colorless and transparent liquid has a different pH from that of the recording medium, and the ink contains a substance that changes color or develops color due to a change in pH, and the action of the component of the colorless and transparent liquid is a surface pH of the recording medium. 3. The latent image printing / optional development method according to claim 2, wherein the image is expressed by a difference in pH between an image drawn by the transparent liquid on the recording medium. 6. The ink jet recording apparatus according to claim 2, wherein the colorless and transparent liquid is printed on the recording medium to form a colorless and transparent image on the recording medium. Characterized in that water and a water-soluble organic solvent are the main components, and the pH thereof is adjusted to a pH range in which the color changes or changes color of an ink containing a substance which changes color or changes color by changing the pH. Colorless transparent ink. 7. The latent image printing method according to claim 5, wherein the substance contained in the ink according to claim 5 which changes color or develops color due to a change in pH is an indicator for detecting an acid and an alkali. -Development method at any time. 8. The ink according to claim 5, wherein the means for visualizing the transparent latent image formed by the colorless transparent ink includes an ink containing a substance that changes color by a change in pH according to claim 5. A latent image printing / optional development set in which the means for applying is a tracing with a writing implement with ink. 9. The latent image printing / optional development set according to claim 8, wherein the writing implement supplies ink from the inside. 10. The latent image printing / optional development set according to claim 8, wherein the writing implement is a felt pen. 11. The latent image printing / optional development method according to any one of claims 2 to 5, or 7,
A latent image printing / optional development method characterized by erasing an image on a recording medium after color development so that the image can be reused for normal printing. 12. A latent image printing / optional development method according to claim 11, wherein the method of erasing a color image is performed under a condition in which a colored dye is not colored. 13. The method for erasing a color image according to claim 11 or 12, wherein the method mainly comprises water and a water-soluble organic solvent.
A latent image printing / optional development method characterized by applying a decoloring liquid containing a substance whose pH is decolored by a change in pH or returned to its original color by discoloration. 14. A latent image printing and occasional development method according to claim 11, wherein the method of erasing a color image according to claim 11 is to separate and separate the color of the colored dye itself. 15. The pH according to claim 5, wherein the color-separated colorant according to claim 14 is a colorant.
A latent image printing / optional development method, which is an ink containing a substance that changes color or develops color by a change.