JPH01190772A - Ink for image recording - Google Patents

Abstract

PURPOSE:To obtain the title ink which can realize a reduction in an applied voltage and prevent the necessary applied voltage from being increased due to a decrease in the amount of the solvent of the ink, by adding a reducing agent which can be oxidized at a potential baser than the electrolysis potential of the solvent of the ink. CONSTITUTION:0.2-50 pts.wt. hydrophilic polymer (e.g., PVA) of a particle diameter of 0.01-100mum and 0.1-40wt.% reducing agent which can be reduced at a potential baser than the electrolysis potential of the liquid dispersing medium of the ink (e.g., 1-phenyl-3-pyrazolidone) and at least 0.01 pt.wt. dye or pigment (e.g., carbon black) are homogeneously mixed with 100 pts.wt liquid dispersing medium of viscosity >=5000cp, comprising water and water-soluble organic solvent (e.g., ethlene glycol), and the mixture is allowed to gel by cooling to obtain an ink for image recording, which is nonsticky and can be made sticky by application of electric current.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an image recording ink that can be suitably applied to an image recording method that enables low-cost recording while maintaining the advantages of conventionally used recording methods. Regarding.

[Conventional technology]

In recent years, with the rapid development of the information industry, various information processing systems have been developed, and recording methods and recording devices have been developed and adopted for each information system. Among these, typical plain paper recording methods include electrophotography and its derivative laser beam printers, inkjet printers, thermal transfer printers, impact printers (
(using wire dots, daisy foil, etc.).

Impact printers are extremely noisy and difficult to fully multi-purpose. Electrophotography, laser beam printers, etc. have high image quality resolution, but the equipment is complex and large,
The equipment cost is also high. Although inkjet ink jets have low consumable costs, they eject low-viscosity liquid ink from thin nozzles, which causes the ink to solidify and clog easily when not in use. Furthermore, the ink used for inkjet has a low viscosity, so after the ink is transferred to the paper,
Blurring and image blurring are likely to occur.

In addition, the thermal transfer method is a method in which patterned heat is supplied to a solid ink layer provided on a sheet-like support, and the ink is melted and transferred onto plain paper, etc.; , a relatively small-sized device is used, and the device cost is low. However, since an ink ribbon consisting of a solid ink layer provided on an expensive support is used, and this ribbon is disposable, this thermal transfer method has the drawback of increasing the cost of consumables.

[Problem to be solved by the invention]

The present inventors have previously proposed an image recording device that eliminates the above-mentioned drawbacks and is capable of low-cost recording (Japanese Patent Application No. 61
-175191).

This image recording device includes: an ink carrier that has a surface capable of carrying a layer of fluid ink and is moved along an ink transfer position; and an ink carrier formed on the ink carrier at the ink transfer position. a transfer medium that is moved so as to be able to come into contact with the ink layer on the ink carrier; and an energy application means that makes it possible to apply energy to the ink layer on the ink carrier; This is an image recording device that allows fluid ink to be transferred onto a transfer medium.

The ink used in this image recording apparatus is an image recording ink that can be used without being in the form of a disposable ink ribbon or ink sheet due to the recording method.

More specifically, it is an ink that does not adhere to or transfer to a transfer medium consisting of an intermediate transfer medium or a recording material (final transfer medium) simply by contacting the medium, and is retained on a conventional ink ribbon or ink donor film. Unlike solid inks, inks can be used without being coated as a thin layer of solid ink on a support.

However, this image recording ink requires electrolysis of the solvent during recording, and it is necessary to apply a relatively high voltage. Another drawback is that a higher voltage is required to be applied in order to increase the printing speed or improve the image density.

In addition, since the solvent is electrolyzed, the amount of solvent decreases due to electrolysis, and furthermore, the amount of solvent decreases due to evaporation, which causes the required current recording voltage to gradually become lower.

An object of the present invention is to provide an image recording ink that is particularly suitable for use in a new recording method that eliminates the drawbacks of conventional image recording methods. More specifically, it is an object of the present invention to provide image recording that can reduce the applied voltage and prevent an increase in the required applied voltage due to a decrease in the amount of solvent due to drying, evaporation, and electrolysis of the solvent contained in the ink. The objective is to provide ink for

[Means to solve the problem]

As a result of intensive research on fluid ink suitable for use in the recording device of the above-mentioned Japanese Patent Application No. 175191/1987, the present inventor found that the ink in the ink that can be printed due to the adhesiveness control by applying electricity. It has been found that by containing a reducing agent that is oxidized at a potential less base than the electrolytic potential of the solvent contained in the inkjet ink, it is possible to lower the voltage applied for printing. Furthermore, it has been found that doing so also prevents an increase in the required current voltage due to a decrease in the amount of solvent due to solvent electrolysis and dry evaporation.

The image recording ink of the present invention is based on this knowledge, and is an ink that can be printed by controlling tackiness based on the application of electricity, and has an electrolytic potential that is less base than the electrolytic potential of the inorganic or organic solvent contained in the ink. It contains a reducing agent that is oxidized by electric potential.

As will become clearer from the drawings later, an image recording device that can suitably use the image recording ink of the present invention has a surface that can carry an ink layer and move it along the ink transfer position. an ink carrier, a transfer medium that is moved so that it can come into contact with the ink layer on the ink carrier at the ink transfer position, and means for applying current to the ink layer on the ink carrier, and The invention is characterized in that the ink imparted with tackiness by the application of a target can be transferred onto a transfer medium.

By using the ink of the present invention in a recording apparatus having such a configuration, it becomes possible to directly and selectively impart tackiness to the ink layer formed in a layered manner on the ink carrier.

Therefore, by using the image recording ink of the present invention, a high-cost ink in which a solid ink layer is formed by a complicated process on an expensive sheet-like support (which was essential in the conventional thermal transfer method) can be avoided. Since ribbons and ink sheets are no longer required, it is possible to significantly reduce the cost of consumables.

Hereinafter, the present invention will be described in further detail with reference to the drawings as necessary. In the following description, the invention will be explained in more detail. In the following description, "%" and "part" expressing quantitative ratios are based on weight unless otherwise specified.

The image recording ink of the present invention is an ink that has substantially no tackiness and can be imparted with tackiness by applying electricity.

More specifically, the ink of the present invention is preferably an ink as shown below.

(1) Film-forming property The term "ink with film-forming property" herein refers to an ink that has the property of forming an ink film. “Film formability” means
For example, it means that ink can be formed in a layer on a carrier.

The ink of the present invention preferably has film-forming properties such that an ink layer of 0.1 mm or more is formed on a stainless steel surface with a surface roughness of IS.

(2) Gently place a 5cm x 5cm piece of aluminum foil (after weighing accurately) on the surface of the fluid ink placed in a non-adhesive (or liquid dispersion medium retaining) container, and leave it at a temperature of 25°C.
After being left in an atmosphere with a humidity of 60% for 1 minute, the aluminum foil was gently peeled off from the ink surface, and the aluminum foil was quickly and accurately weighed to determine the weight increase of the aluminum foil. In this case,
In the ink of the present invention, the solid component is not substantially transferred to the aluminum foil piece, and the weight increase of the aluminum foil is 0 to 100.
It is preferable that the amount is about 0 mg, (or even 0 to 100 mg). When peeling off the entire ink in the container and the aluminum foil, if necessary, gently peel it off with a spatula etc.
You can also weigh it.

If the non-adhesiveness of the ink of the present invention is weaker than the above-mentioned level, the transfer of the ink itself to the transfer medium during application of electricity will be to such an extent that it cannot be ignored in practice, resulting in a decrease in image quality.

The above-mentioned ink having film-forming properties and non-adhesion properties is an ink having a gel state in a broad sense in which a liquid dispersion medium is held by a crosslinked structure substance, or an ink having a relatively high viscosity (preferably 5000 centivoise (Cps) or more). in the dispersion medium of
It is preferable that the ink is a sludge-like ink formed by dispersing particles (having a particle diameter of preferably 0.01 to 100 μm, preferably 0.1 to 20 μIn). An ink having properties of both a gel-like ink and a sludge-like ink is more preferably used.

Among these inks, in the former gel-like ink, the liquid dispersion medium is well retained in the gel, so if no electricity is applied, the ink (except for a small amount of the liquid dispersion medium) will not transfer to the transfer medium. It is estimated that there is no substantial transfer to the

In addition, in the latter type of sludge-like ink, the particles are closely arranged at the ink interface, which suppresses the contact of the dispersion medium with the transfer medium. It is thought that it is not transferred to In particular, in this sludge-like ink, when a rotating ink carrier is used as an ink carrier, the particles in the ink are arranged on the surface (outer periphery) of the ink layer due to centrifugal force, and this ink behaves like a dilatant fluid. Therefore, it is preferable.

When the above-mentioned gel-like ink or sludge-like ink is given a change in pH value by applying electricity in a pattern, the cross-linked structure, ionic structure, or arrangement of particles changes, resulting in a pattern-like change in the ink. It is estimated that the adhesiveness is imparted to the product.

The image recording ink of the present invention having the above-mentioned characteristics contains, in addition to the reducing agent, a liquid dispersion medium and a crosslinked structure substance (or polymer electrolyte) that holds the liquid dispersion medium.

Here, ``Crosslinked structure material j'' refers to a substance that can form a crosslinked structure by itself, or a substance that forms a crosslinked structure by adding other additives (for example, a crosslinking agent made of inorganic ions such as borate ions). A substance that makes it possible to

Furthermore, the term "crosslinked structure" refers to a three-dimensional structure having "crosslinked bonds."

In the ink of the present invention, this "crosslinking bond" may be composed of any one of a covalent bond, an ionic bond, a hydrogen bond, or a van der Waals bond (or a combination of two or more types).

In the ink of the present invention, the above-mentioned "crosslinked structure" need only be of such a degree that the desired liquid dispersion medium retention property can be obtained. In other words, this crosslinked structure is, for example, network-like, honeycomb-like,
It may have any structure such as a spiral structure, and may not have a regular structure.

In the ink of the present invention, various inorganic or organic solvents that are liquid at room temperature can be used as the liquid dispersion medium, but they have relatively low volatility (for example,
It is preferable to use a solvent that is equivalent to or lower than water.

When using a hydrophilic dispersion medium such as water or a water-containing dispersion medium as the above-mentioned liquid dispersion medium, a hydrophilic (
Natural or synthetic) polymers are preferably used.

Examples of such hydrophilic polymers include guar gum,
Plant-based polymers such as locust bean gum, gum arabic, taragant, carrageenan, pectin, mannan, and starch; Microbial-based polymers such as xanthan gum, dextrin, succinucan, and curdlan; Animal-based polymers such as gelatin, casein, albumin, and collagen. Polymers: Cellulose-based polymers such as methylcellulose, ethylcellulose, and hydroxyethylcellulose, starch-based polymers such as soluble starch, carboxymethyl starch, and methyl starch, alginic acid-based polymers such as propylene glycol alginate, and alginate, and other polysaccharide-based polymers. Semi-synthetic polymers such as derivatives of polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, carboxyvinyl polymer, sodium polyacrylate, etc.Other vinyl polymers such as polyethylene glycol, ethylene oxide, propylene oxide block copolymers, etc. Synthetic polymers and the like are preferably used alone or in combination of two or more as necessary.

It is preferable to use these hydrophilic polymers in a range of 0.2 to 50 parts, sometimes 0.5 to 30 parts, per 100 parts of the liquid dispersion medium.

In the ink of the present invention as outlined above, at least a part of the crosslinked structure is changed or destroyed due to a change in pH value,
From a gel state to a sol state (reversibly), p
Adhesiveness is imparted according to changes in H value. Alternatively, the dissociation state of the polymer electrolyte changes due to a change in pH value, and tackiness is imparted in accordance with the change in pH. The ink of the present invention having such properties contains a reducing agent, which is a feature of the present invention.

The reducing agent used in the ink of the present invention is oxidized at a potential less noble than the electrolytic potential of the solvent in the ink, thereby releasing hydrogen ions and imparting tackiness to the ink. Therefore, the reducing agent can reduce the applied voltage during recording.

Adhesiveness is imparted by applying electricity by cutting the crosslinked structure of the ink at the print side, for example at the anode, due to a decrease in pH value.

According to the findings of the present inventors, the crosslinking structure of the ink changes due to the pH value change due to electricity supply, for example, when a crosslinked product of polyvinyl alcohol and borate ions is bonded to the OH group of polyvinyl alcohol and crosslinked. From the borate ion, the pH value changes to the acidic side due to an anodic reaction near the anode (or addition of an electron pair acceptor such as hydrochloric acid), electrons are taken away, and a crosslinked structure (at least a part of it) is formed. It is presumed that this is because the ink was destroyed and selective tackiness was imparted to the ink.

According to the knowledge of the wood inventors, the reaction at this time is estimated as follows, for example.

The above sol-gel transition occurs due to changes in pH, and varies depending on the degree of polymerization, degree of saponification, and amount of boric acid ions of polyvinyl coal, but as the pH increases, gelation progresses, and as the pH decreases, sol formation progresses. .

The electrochemical reaction of a solvent, for example the electrolysis of water, caused by the application of electricity is expressed by the following equation.

On the anode side, 20H-→)(2o+Ho,,T+2e-
, on the cathode side, 2 H++2 e ”−−+ % H7↑
As a result of this reaction, the balance of hydrogen ions is disrupted near the electrode, resulting in acidification on the anode side, alkalization on the cathode side, and sol formation of the ink on the anode side, allowing adhesive recording, and gelation progresses on the cathode side.

However, patent application No. 61-17519 utilizing this reaction
In the method started with No. 1 etc., the pH was changed by electrolysis of water, so it was necessary to apply a relatively high potential. Also, since water was electrolyzed, the voltage required for recording due to the decrease in water content increased. I become like a dog.

However, when using the ink of the present invention that contains a reducing agent that is oxidized at a potential that is more base than the electrolysis potential of the solvent, for example when using an ink containing hydroquinone as a reducing agent, the electrolysis of water The following reactions occur with priority.

After the electrode reaction proceeds, the pH near the anode decreases and the following chemical reaction proceeds, which makes it possible to perform adhesive recording by solizing the ink on the anode side.

As a result, the addition of the reducing agent causes an oxidation reaction of the reducing agent at a potential that is more base than the electrolytic potential of the solvent, resulting in a pH
As a result, adhesive recording becomes possible with lower voltage than before. It is also possible to prevent an increase in recording voltage due to evaporation of the solvent.

For the above reasons, a reducing agent is used in the ink of the present invention.

The reducing agent used in the ink of the present invention is a compound that decomposes in an electrochemical reaction at a potential lower than the decomposition potential of the solvent and releases protons. Specific examples of preferred reducing agents include 1-phenyl-3-pyrazolidone (phenidone), 4-methyl-1-phenyl-3-pyrazolidone, 4.4-dimethyl-1-phenyl-3-pyrazolidone, 4-ethyl -1-phenyl-3-pyrazolidone, 5-methyl-1-phenyl-3-pyrazolidone, 5
-Phenyl-3-pyrazolidone, 5,5-dimethyl-1
-Phenyl-3-pyrazolidone, 4,4-dihydroxymetal-1-phenyl-3-pyrazolidone, 4-methyl-4-hydroxymethino-1-phenyl-3-pyrazolidone, 4,5-dimethyl-1-phenyl-3 -pyrazolidone, 1-p methoxytuunyl-3-pyrazolidone, 1
p-tolyl-3-pyrazolidone, pyrazolidone derivatives such as 2- and droxymethyl-1-phenyl-3-pyrazolidone, p (or m or 0)-aminophenol, 2
, 6-dichloro-p-aminophenol, 2,6-dimethyl-p-aminoneenol, 3,5-dimethyl-p-
Aminophenol derivatives such as aminophenol, hydroquinone, methylhydroquinone, catechol, p-7crt-butylcatechol, chlorohydroquinone, p
- Polyhydroxybenzene such as methoxyphenol, alkoxyphenol, etc., p-anisidine, 0-anisidine, 0 (or m or p)-phenylenediamine, 2
．． These include 4-tolylene diamine, 3,4-tolylene diamine, and the like.

Two or more of these reducing agents can be used simultaneously.

The amount of reducing agent used is usually 0, based on the total amount of ink.
．． 1% to 40%, preferably 1% to 20%. 0.1
If it is less than 40%, the effect of the reducing agent will be small, and if it exceeds 40%, the gel state of the ink will change, making coating difficult, which is not preferable.

The image recording ink of the present invention preferably comprises the above-mentioned liquid dispersion medium, a crosslinked structure substance (or polymer electrolyte), and a reducing agent. agent, a color-forming compound that develops color due to a change in pH value, or an electrolyte that imparts the desired conductivity to the ink and enables the ink to generate heat when energized, and if necessary, a fungicide, a preservative, etc. may contain additives.

As the above-mentioned coloring agent, dyes and pigments generally used in the printing and recording fields, such as carbon black, can be used without any particular restrictions, but the coloring agent may be used without any particular restrictions. From the viewpoint of suppressing discoloration due to adhesion of the dispersion medium as much as possible, it is preferable to use dyes and pigments (particularly pigments) that have a relatively low affinity for the liquid dispersion medium.

These dyes and pigments are used in an amount of 0.1 parts per 100 parts of liquid dispersion medium.
It is preferable to use at least 5 parts, more preferably 5 to 50 parts (especially 10 to 30 parts).

As the coloring agent, colored particles (for example, toner particles of various colors used in electrophotography) obtained by dispersing the dye and pigment in a natural or synthetic resin and forming fine particles may be used. An ink containing such colored particles exhibits dilatant fluid-like behavior, and is therefore particularly preferred from the standpoint of transferring the liquid dispersion medium to the transfer medium or suppressing coloring when the pH value remains unchanged.

Such colored fine particles are used in an amount of 1 part or more, more preferably 5 to 100 parts (especially 20 to 80 parts), based on ioo parts of the liquid dispersion medium.
It is preferable to use it. Furthermore, in general, when the diameter of the fine particles is increased, it is desirable to increase the fine particle content in the ink from the viewpoint of colorability.

In the present invention, the toner particles can be used regardless of their electrophotographic properties such as chargeability.

In order to obtain the image recording ink of the present invention, for example, a liquid dispersion medium such as water and a crosslinked structure material (
If necessary, a viscous solution or dispersion may be obtained by uniformly mixing with a crosslinking agent, a coloring agent, an electrolyte, etc. while heating, and then cooling and gelling.

In addition, when adding a basic component for the purpose of adjusting the ink pH, NaOH, KOH, Na2CO3 and other strong,
A weak base may be added as appropriate.

Further, for the purpose of adjusting the conductivity of the ink when energy is applied, salts such as NaCl, LiCl, KCI, etc. may be added.

In the image recording ink of the present invention, water itself is preferably used as the liquid dispersion medium, but if necessary, a mixture of water and a water-soluble organic solvent may be used for the purpose of preventing drying of the ink, maintaining wettability, etc. is also preferably used.

Examples of water-soluble organic solvents include methyl alcohol,
Ethyl alcohol, n-propylene alcohol, isopropylene alcohol, n-butyl alcohol, 5ee-
Alkyl alcohols with 1 to 4 carbon atoms such as butyl alcohol, tert-butyl alcohol, and isobutyl alcohol Amides such as dimethylformamide and dimethylacetamide; Amides such as acetone and diacetone alcohol; Ketones such as acetone and diacetone alcohol or keto alcohols: tetrahydrofuran, dioxane, etc.; N-methyl-2-pyrrolidone, 1,3
-Nitrogen-containing heterocyclic ketones such as dimethyl-2-imidazolidinone: polyethylene glycol, polypropylene glycol/polyalkylene gelcol, butylene glycol, triethylene glycol, 1,2,6-hexandriol, thiodiglycol, hexylene glycol,
Alkylene glycols containing 2 to 6 carbon atoms such as diethylene glycol; glycerin; polyhydric alcohols such as ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monoethyl (or ethyl) ether; Examples include lower alkyl ethers; amines such as triethanolamine; and the like.

In addition, when using colored particles such as toner particles as a coloring agent, it is preferable to add the colored particles after mixing the crosslinked structure material and the liquid dispersion medium while heating to make them uniform. Further, in this case, it is particularly preferable to mix at around room temperature in order to prevent agglomeration of toner particles and the like.

Next, the role of electricity supply will be explained. It is responsible for changing the pH value in the vicinity of the electrode through an electrochemical reaction. That is, the transfer of electrons by the recording electrode causes a change in ink adhesion due to a change in the crosslinked structure or a change in the dissociation state of the electrolyte.

When applying a pH change to the ink using electrodes in this way, this pH value change selectively diffuses in the depth direction of the ink (current flow direction). (unlike diffusion), clarifying the ink pattern (cutting,
image quality).

Next, a preferred embodiment of the image recording method using the ink of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a schematic sectional view showing an example of an image recording apparatus using the ink of the present invention, and FIG. 2 is a perspective view thereof. The gel-like fluid ink 2 is carried while being supported on the surface of the ink transfer roll 1 as the ink transfer roll 1 rotates in the six directions of the arrows.

The ink 2 being conveyed is passed by the coating roll 4 rotating in the direction of arrow E to form an ink reservoir 3, and the ink 2 stored in this ink reservoir 3 is transferred to the ink transport roll 1.
A layer of ink 2 whose thickness is controlled to be constant is formed on the surface. This ink 2 comes into contact with the recording electrode 5 and is applied with a patterned voltage according to the image signal. A current based on the voltage flows from the recording electrode 5 through the ink 2 to the ink transport roll 1, thereby forming an ink image 2a in which the fluid ink 2 is given selective tackiness.

The ink image 2a is further conveyed in the six directions of the arrows and reaches a position where the layer made of the ink 2 comes into contact with the intermediate transfer roll 6 rotating in the direction of the arrow B. At least a portion of the ink 2 constituting the ink layer formed on the roll 1 is transferred onto the intermediate transfer roll 6 to form an ink pattern 2b.

Ink pattern 2 formed on this intermediate transfer roll 6
b is transferred as the roll 6 rotates in the direction of arrow B, and is transferred onto the recording paper 8 by the transfer roll 7 rotating in the direction of arrow C at the ink image transfer position to form a transferred recorded image 2c. . The transferred recorded image 2c thus formed on the recording paper 8 is transferred to the conveyor rolls 9a, 9 along with the recording paper 8.
b, 9c, and 9d are transported in the direction of the arrow.

After the ink pattern 2b is transferred onto the recording paper 8, the ink remaining on the surface of the intermediate transfer roll 6 is removed by the cleaning means 1.
0 and used again to form a new ink pattern 2b. On the other hand, the ink image 2a' and the fluid ink 2 that were not transferred to the intermediate transfer roll 6 at the ink transfer position are further transferred in the six directions of the arrow, return to the ink reservoir 3, and can be used again based on their fluidity. be done. The ink image 2a' and the fluid ink 2 that have returned to the ink reservoir 3 are stirred by the rotation of the ink transfer roll in six directions and the rotation of the coating roll 4 in the E direction, and become uniform components, forming a constant film again. It is layered thickly and can be recorded repeatedly following a similar process.

In the above-described ink pattern forming step, that is, the step in which the ink pattern 2b is formed by selectively transferring the fluid ink 2 to the intermediate transfer roll 6, at the separation position between the intermediate transfer roll 6 and the ink layer, the ink is The shear force applied to the layer is rather a negative value. For this reason, by slowing down the circumferential speed of the intermediate transfer roll 6 (although it may be made constant with respect to the circumferential speed of the ink transport roll 1), the ink layer can be
- It is preferable to provide a shearing force based on this difference in circumferential speed from the viewpoint of stabilizing the peeling of the ink layer from the intermediate transfer roll 6. Since this fluid ink 2 is an ink having a broadly defined gel state in which a liquid dispersion medium (or vehicle) is held by a crosslinked structure substance, it is estimated that it is not substantially transferred to the intermediate transfer roll 6 when no energy is applied. Ru. In addition, since electrical energy is used as an image signal, if a crosslinked structure material of the fluid ink 2 is, for example, guar gum or polyvinyl alcohol crosslinked with boric acid ions, this crosslinked structure can be used to impart tackiness. For such inks, the amount of current required to cut off (at least a part of) due to a change in the pH of the solvent is usually quite small (for example, several hundred pp for the ink).
pm) only the amount necessary to transfer electrons to and from the added crosslinking agent (for example, the borate ions mentioned above) is sufficient.

This amount of current may be approximately 1/10 of the amount of current when using a thermal head, so by utilizing such electrochemical changes, recording with lower energy consumption can be achieved.

The recording electrode 5 is, for example, a plurality of electrode elements 5b made of metal such as platinum or gold provided on a substrate 5a, as shown in a partial schematic perspective view in FIG.
A recording electrode is preferably used in which an insulating coating 5c made of polyimide or the like is provided on a portion other than the upper tip portion (the portion that contacts the ink). As the electrode element 5b, one formed by electroless plating of platinum is preferably used from the viewpoint of adhesion to the base material and durability.

In the configuration shown in FIG. 1, electricity is supplied between the recording electrode 5 and the ink transport roll 1, but it may also be supplied between the recording electrode 5 and the intermediate transfer roll 6, or the recording electrode Current may be passed between the plurality of electrode elements 5b on each other.

In the above, the embodiment of the present invention has been mainly described in which the fluid ink is an ink having a gel state in a broad sense, and the fluid ink is selectively turned into a sol state to impart tackiness by applying energy. (e.g. p
By making H acidic), the ink pattern may be formed into a sol state that is sticky or adhesive when no energy is applied, and selectively put into a gel state (non-adhesive) by applying electrochemical energy, for example. .

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but these are not intended to limit the present invention in any way.

Example 1 Propylene glycol 20g water
6g Polyvinyl alcohol 6g (Gohsenol GL-03 manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.) Potassium iodide 3.5g Carbon black 2.5g (Sterling SR1 manufactured by Capot Co., Ltd. in the United States) The above components were uniformly dissolved while heating to 80 to 90°C. After that, 3 g of silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) and hydroquinone (as a reducing agent) were added.
0.4 g of special grade reagent manufactured by Kishida Chemical Co., Ltd.) was added and sufficiently dispersed. Thereafter, 2.5 g of a solution of sodium tetraborate, decahydrate (Na2 B407.10H20) dissolved in 20% by weight propylene glycol was added to this to form a gel, and 0.3 g of IN sodium hydroxide was added to the solution. The mixture was mixed to obtain a fluid, gel-like ink.

Take a part of the ink of Example 1 and add 5 c+
Gently place the aluminum foil of nx 5 c+n on it and leave it for 1 minute in an atmosphere of 25℃ and 60% room temperature.
When the aluminum foil was gently peeled off from the ink surface and accurately weighed, there was virtually no increase in the weight of the aluminum foil (weight increase of 0.1 g or less).

The gel ink thus obtained was applied to the recording apparatus shown in FIG. 1, and an image forming test was conducted. That is, (
(See Figure 1) An ink transfer roll 1 consisting of a stainless steel cylindrical roll (40 mm diameter) (surface roughness 100S) and an iron cylindrical roll (40 mm diameter) with a hard chrome plated surface.
Using the image recording apparatus shown in FIG. 1, in which the intermediate transfer roll 6 consisting of a roller (mφ) faces each other with a gap of 1 mm at the ink transfer position, the gel of the present invention obtained as described above is placed in the ink reservoir 3 of this apparatus. Ink 2 was added. When the ink transport roll 1 was rotated in the direction of the arrow at a rotation speed of about 10 ppm to form a layer of fluid ink 2 on the roll 1, the fluid ink of the present invention was suitably coated on the ink carrying roll 1. The surface of the coated ink layer was extremely smooth, and uniform coating could be achieved.

While in contact with the layer formed on the ink transport roll 1 in this way, the intermediate transfer roll 6 is rotated at approximately 10 rpm in the direction of arrow B.
It was rotated at a rotation speed of . At this time, the recording chamber 8i5 (insulating film 5C made of polyimide) having the shape shown in FIG.
The area of the electrode element 5b formed by platinum, electroless plating, and the exposed portion of the electrode element 5b is 1 mm x 1 mm). Although a very small amount of water was transferred, the ink 2 was not substantially transferred onto the intermediate transfer roll 6. On the other hand, with the recording electrode 5 as an anode and the ink transfer roll 1 as a cathode, ink is transmitted through the ink 2 at 5v, 10v and 15v.
When a pulse of 25 m5ec was applied, the ink 2 was selectively transferred onto the intermediate transfer roll 6, forming an ink pattern 2b. At the ink image transfer position, a pressure roll 7 (20 mm φ When a 10 mm thick silicone rubber layer was placed on a steel support tube roll (10 mm) and a slight pressure was applied from this pressure roll 7, a pattern (corresponding to the above-mentioned ink pattern 2b) was formed on the recording paper 8.
A cyan dot image 2c (with a size of 1 mm x 1 mm) was obtained.

When the applied potential was 10 V and 15 V, the transferred recorded image 2C obtained on the recording paper 8 was a high-quality image with no trailing, fogging, etc. and high image density (indicated by Good in Table 1). .

Example 2 An experiment similar to Example 1 was conducted except that 0.8 g of hydroquinone was used instead of 0.4 g of hydroquinone used in Example 1. The results are shown in Table 1.

Example 3 An experiment similar to Example 1 was conducted except that 0.8 g of 0-nitro-p-phenylenediamine was used instead of 0.4 g of hydroquinone used in Example 1. The results are shown in Table 1.

Comparative Example An ink similar to that of Example 1 was prepared without using ehydroquinone, and an image printing experiment was conducted.

The results are shown in Table 1.

〔Effect of the invention〕

As mentioned above, the present invention not only has the following effects (a) and (b) over the known technology, but also newly provides (C
) has the effect of

(8) By eliminating the need for the conventionally used high-cost ink ribbon having a solid ink layer, an image recording ink capable of recording at an extremely low running cost is proposed.

(b) An image that is a simple method and has significantly lower recording costs than the thermal transfer recording method, and also eliminates the disadvantages of the inkjet method, such as nozzle clogging, smearing, trailing, and fogging of the recorded image, resulting in decreased image quality. Recording becomes possible.

In particular, in a preferred embodiment of the present invention in which the cross-linked structure of the ink is changed by applying electricity, image recording can be performed with approximately 1/10 the current amount of the conventional thermal transfer method (thermal head drive), and the device can be started up. Since the selective ink manufactured by the company is also good, it is possible to significantly reduce costs in terms of energy consumption.

(C) By including a reducing agent, it is possible to (1) improve image density in low-potential reverse electromagnetism, and (2) prevent an increase in the required recording voltage due to a decrease in the amount of solvent due to electrolysis and evaporation of the solvent. This makes it possible to improve the stability of ink use and image quality.

[Brief explanation of the drawing]

FIG. 1 is a schematic side sectional view showing an aspect of an apparatus system for carrying out an image recording method using the image recording ink of the present invention, FIG. 2 is a perspective view thereof, and FIG. FIG. 2 is a schematic perspective view showing the configuration of a recording electrode. 1... Ink transfer roll, 2... Ink, 2a, 2a'... Ink image, 2b... Ink pattern, 2c・
......Transfer recorded image, 3...Ink reservoir, 4...Coating roll, 5...Recording electrode, 7... ...Pressure roll, 8...Recording paper, 9...9a, 9b and 9c, 9d...
- Conveyance roll, 10...Cleaning means, 11...Ground.

Claims (1)

[Scope of Claims] 1) An image recording ink that has substantially no tackiness and can be imparted with tackiness by application of electricity, characterized by containing a reducing agent. 2) A claim in which the ink is imparted with adhesive properties on the anode side of the electrode to which electricity is applied, and contains a reducing agent that is oxidized at a base potential by the electrolysis potential of the solvent contained in the ink. 1. The image recording ink according to 1.