JPH01190773A - Ink for image recording - Google Patents

Abstract

PURPOSE:To obtain the title ink which is excellent in storage stability and stability in a continuous use and can be reused even when it remains unused in image recording, by mixing a liquid dispersing medium with a crosslinking substance and a solid acid comprising a metal oxide. CONSTITUTION:100 pts.wt. liquid dispersing medium comprising water and a water-soluble organic solvent (e.g., methyl alcohol) is homogeneously mixed under heating with 0.2-50 pts.wt. crosslinking substance (e.g., a product of crosslinking of PVA with boric acid), at least 0.1 pt.wt. corolant of a particle diameter of 0.01-100mum and 0.1-20wt.% solid acid comprising a metal oxide (e.g., SiO2-Al2O3), and the mixture is allowed to gel by cooling to obtain an ink for image recording, which can be made sticky by application of electric current.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an image recording ink suitable for use in an image recording method that enables low-cost recording while maintaining the advantages of conventionally used recording methods.

[Background 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 processing system. Among these, typical plain paper recording methods include electrophotography and its derivative laser beam printer,
Alternatively, inkjet printers, thermal transfer printers, impact printers (using wire dots, daisy foils, etc.), and the like can be used.

Impact printers make a lot of noise and are difficult to fully print. 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, since the ink used for ink jetting is a low viscosity ink, bleeding and blurring of the image are likely to occur after the ink is transferred to the paper.

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 comprising a solid ink layer provided on an expensive support is used, and this ribbon is disposable, this thermal transfer method has the disadvantage of increasing the cost of consumables.

The present inventors have previously proposed an image recording method that eliminates the above-mentioned drawbacks and enables low running cost recording (Patent Application No. 61
-175191).

This image recording method uses a fluid ink that has fluid film forming properties but is substantially adhesive, and can be imparted with adhesive properties by applying energy, and the fluid ink is applied onto an ink carrier. a step of forming an ink layer; a transfer step of supplying energy in a pattern according to an image signal to the ink layer and transferring fluid ink imparted with tackiness according to the pattern to a transfer medium; This is an image recording method characterized by the following steps.

However, although such new image recording methods enable image recording with low energy consumption, there is still room for improvement in maintaining the image characteristics of the ink during long-term storage or continuous use.

[Purpose of the invention]

An object of the present invention is to provide an image recording ink 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 an image recording ink that is not in the form of a disposable ink ribbon or ink sheet (and that allows ink that is not actually used for image recording to be reused). be.

More specifically, the object of the present invention is to provide an ink that does not adhere to and transfer to a transfer medium consisting of an intermediate transfer medium or a recording material (final transfer medium) simply by contacting the medium,
Unlike fixed ink held on conventional ink ribbons or ink donor films, this ink can be used without being coated as a thin layer of solid ink on a support, and is also storage stable and durable during continuous use. The objective is to provide an ink with excellent stability.

[Summary of the invention]

As a result of intensive research, the present inventor has found that it is possible to improve the stabilization of ink physical properties during continuous printing by adding a solid acid made of a metal oxide to an ink that can be printed by controlling tackiness by applying electricity. I found out.

The image recording ink of the present invention is based on such knowledge, and contains a liquid dispersion medium and a crosslinked structure material that holds the liquid dispersion medium, and is an image recording ink that can be imparted with tackiness by applying an electric current. This ink contains a solid acid made of a metal oxide.

When using an ink containing the above-mentioned solid acid, the physical properties of the ink, especially the pH
It is possible to prevent viscoelasticity from changing due to changes in , and maintain good image quality.

Furthermore, by using the image recording ink of the present invention,
This eliminates the need for high-cost ink ribbons and ink sheets, which require a layer of solid ink on an expensive sheet-like support through a complicated process (essential in conventional thermal transfer methods), reducing consumables costs. This makes it possible to significantly reduce the amount.

Hereinafter, the present invention will be described in further detail with reference to the drawings as necessary. In the following description, "%" represents the quantitative ratio.
"Parts" and "parts" are based on weight unless otherwise specified.

[Detailed description of the invention]

The image recording ink of the present invention is an ink that substantially has tackiness and can be imparted with tackiness by energization.

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" as used 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 amount of the aluminum foil is 0 to 10.
00mg.

(Furthermore, it is preferably on the order of 0 to 100 mg). In addition, when peeling off the entire ink in the container from the aluminum foil, if necessary, it may be gently peeled off with a spatula or the like and weighed accurately.

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 energization will be practically negligible, resulting in a decrease in image quality.

As described above, although the ink of the present invention has film-forming properties, it does not substantially have tackiness, and has the property of becoming tackified when electrical energy is applied. Note that "adhesion" here refers to selective adhesion, and when ink is brought into contact with an object such as an intermediate transfer roll (details will be explained after 6 degrees in Figure 1), a portion of the ink may become ink. It refers to being separated from the whole ink and attached to an object, regardless of whether the whole ink is sticky or not.

Therefore, when no energy is applied to the ink layer formed on the surface of the ink transport roll (described in detail after 1° in Figure 1), the ink comes into contact with other media, such as the intermediate transfer roll. is not substantially transferred to the intermediate transfer roll.

Furthermore, the ink of the present invention has properties as a plastic body when coated on an ink transfer roll, and conversely, it behaves as an elastic body after it is applied with energy by the energy application means and reaches the intermediate transfer roll. It is preferable to have the following properties.

Therefore, the ink used in this example preferably has a certain degree of viscoelasticity (complex elasticity having an elastic term and a viscous term).

The range of the viscoelasticity is the ratio G'/G' of the storage modulus G' and the loss modulus G", which is determined as follows:
Those having a value of about 0.1 to 10 are preferably used.

Here, the storage elastic modulus G' and the loss elastic modulus G'
is obtained as follows. That is, for example, as shown in the schematic perspective view of FIG. 3(A), a sample of the ink 2 of the present invention having a diameter of 25 mm and a thickness of 2 mm is subjected to an angular velocity of 1 rad/ s
Apply a sinusoidal strain γ of ec, detect its stress σ and phase shift δ (Fig. 3 (B)), and calculate the complex modulus G'', storage modulus G', and loss modulus G'' from the following equations. demand.

G''-σ/γ=G'+iG'G': Storage modulus G'': Loss modulus In the complex elastic modulus, if the G'/G' is less than 0.1, it will not work as a plastic body. The lack of behavior results in insufficient ink coating on the ink transfer roll, while if the G'/G' exceeds 10, the behavior as an elastic body is insufficient, leading from the energy application means to the intermediate transfer roll. Elastic recovery between the two ends becomes insufficient.

The size of the sample and the manner in which distortion is applied are values that are considered appropriate for a recording apparatus that uses the ink of the present invention.

The above-mentioned ink that has film-forming properties and non-adhesive properties is an ink that has a gel state in a broad sense in which a liquid dispersion medium is held by a cross-linked structure substance. may be an ink obtained by dispersing 0.01 to 100 .mu.m, more preferably 0.01 to 20 .mu.m).

In this gel-like ink, since the liquid dispersion medium is well retained in the gel, it is presumed that the ink (except for a small amount of the liquid dispersion medium) is not substantially transferred to the transfer medium.

When the above-mentioned gel-like ink is given pattern-like energy by energization, the cross-linked structure, ionic structure, particle arrangement state, etc. change, thereby imparting pattern-like tackiness to these inks. It is estimated that

□A “crosslinked structure substance” here refers to a substance that can form a crosslinked structure by itself, or a substance that can form a crosslinked structure by adding other additives (for example, a crosslinking agent made of inorganic ions such as borate ions). A substance that can be removed.

Further, the term "crosslinked structure J" refers to a three-dimensional structure having a "crosslinked bond."

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" is sufficient as long as it can obtain the desired liquid dispersion medium retention property. 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 a hydrophilic dispersion medium such as water or a water-containing dispersion medium is used as the liquid dispersion medium, a hydrophilic (natural or synthetic) polymer or the like is preferably used as the crosslinked structure substance.

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 polymers such as xanthancum, dextrin, succinoglucan, and curdlan; Gelatin, casein, albumin, collagen, etc. Animal-based polymers: Cellulose polymers such as methylcellulose, ethylcellulose, and hydroxyethylcellulose; starch polymers such as soluble starch, carboxymethyl starch, and methyl starch; alginic acid polymers such as propylene glycol alginate, and alginate; Semi-synthetic polymers such as cane sugar derivatives; vinyl polymers such as polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, carboxyvinyl polymer, sodium polyacrylate; other polyethylene glycols, ethylene oxide-propylene oxide block copolymers Synthetic polymers such as the following are preferably used alone or in combination of two or more as necessary.

These hydrophilic polymers are usually used in an amount of 0.2 to 50 parts, particularly preferably 0.5 to 30 parts, per 100 parts of the liquid dispersion medium.

On the other hand, when using a dispersion medium made of oil such as mineral oil or an organic solvent such as toluene as the liquid dispersion medium,
Metal salts of stearic acid, such as aluminum stearate, magnesium stearate, zinc stearate:
Other metal soaps made of similar metal salts of fatty acids such as palmitic acid, myristic acid, and lauric acid, or hydroxypropyl cellulose derivatives, dibenzylidene-D
- Organic substances made of sugar derivatives such as sorbitol, sucrose fatty acid esters, and dextrin fatty acid esters are preferably used alone (as with the hydrophilic polymers mentioned above) or in combination of two or more as necessary.

When using hydrophilic polymers or metal soaps as described above, the retention of the liquid dispersion medium and the fluidity of the ink will change to some extent depending on the amount of these ingredients or the combination of these and the liquid dispersion medium. do. Although it is somewhat difficult to unambiguously determine the amount or combination of these components, the ink of the present invention containing a liquid dispersion medium and a crosslinked structure material has the above-mentioned non-adhesive property ( It is preferable to configure the structure to such an extent that it has good film-forming properties (retention of liquid dispersion medium) and film-forming properties.

In addition to the above-mentioned liquid dispersion medium and crosslinked structure substance, the image recording ink of the present invention contains a solid acid made of a metal oxide.

By adding a solid acid made of such a metal oxide, pH buffering properties are imparted to the ink of the present invention, and the storage stability and stability during continuous use of the ink are significantly improved.

In the ink of the present invention, at least a part of the crosslinked structure is changed or destroyed by the pH change due to electricity supply, and the ink changes from a gel-like state to a (reversibly) sol-like state, and changes in accordance with the energy application pattern. Gives stickiness.

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, the crosslinking structure changes. The pH value changes from the borate ion 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 the crosslinked structure (at least part of it) changes to the acidic side. ) is destroyed, imparting selective tackiness to the ink.

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

■ OH2 C-OH 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 alcohol, but as the pH increases, gelation progresses and the pH increases.
As the value decreases, solization progresses.

In addition, in an electrochemical reaction when electricity is applied, water electrolysis occurs at the anode side with 20H"'-)H3O+ -02↑+2e-■ At the cathode side, 2H"+2e-→ -H2↑ With this reaction, the balance of hydrogen ions changes between the electrodes. Since the ink is acidified on the anode side and alkalinized on the cathode side, adhesive recording is possible by solization of the ink on the anode side, and gelation progresses on the cathode side.

Therefore, based on the above reaction, when the ink that has transitioned from gel to sol state on the anode side is transferred to the transfer target, the acidified sol state ink will be transferred, and when looking at the ink as a whole, the acidic Reduces the amount of ink that has become stained.

On the other hand, on the cathode side, the ink becomes basic, gelation progresses, and the ink hardens. Since this hardened ink is not transferred, if energization recording is performed continuously, the overall p of the ink is
The H value increases and hardens, impeding film formability, making recording difficult.

However, since the image recording ink of the present invention contains a solid acid made of a metal oxide, the pH change due to the above-mentioned electrical reaction is suppressed, and even if energization recording is performed continuously, image recording is possible. A suitable pH condition is maintained.

As the metal oxide used in the present invention, a composite oxide containing two types of metal ions is particularly effective. The reason why solid acids made of metal oxides have the effect of stabilizing the pH value is not necessarily clear, but silica-alumina (Sin
The reason will be explained using 2-Aj7203) as an example.

SiO□-A1203, which is a solid acid, is not simply a mixture or sintered body of 5i02 crystal and Al2O3 crystal (
, 5i02 skeleton is thought to have randomly distributed An. 5i02-Aj! Regarding the reason why 203 exhibits stronger acidity than silica or alumina, which are single oxides, the one proposed by Thomas from the standpoint of structural theory is the most accepted (for example, published in the monthly magazine "Surface"). , voA, 21.No, 12 (1983)
, pp. 43-53). According to it, the following T h
In omas model-8i-0, Al2. +3 for each of Si and O. +4. −
When a charge of 2 is given, there is an average excess of -% negative charge per Al-◯ bond, so protons (hydrogen ions) that neutralize this are generated and become a source of acidity.

On the other hand, at the cathode, H+ is consumed by H" + e--H2↑, and OH- becomes excessive and gelation progresses. However, when silica-alumina is present, H+ To occur,
Excess ○H- is reduced by the reaction H++ OH-→H20, and the PH value is returned to its original state, thereby preventing the progress of gelation.

In addition, at the anode, due to the reaction of ■ 20H-- "→H20+-02↑+2e-, OH- is consumed and H+ becomes excessive and becomes a sol.
This reaction occurs only near the electrodes, and the sol-formed portion is transferred to the transfer target and used for image formation, so the change in pH value of the ink is extremely small.

For these reasons, the pH value of the ink as a whole is
It is stably controlled and viscoelasticity and adhesiveness can be kept constant.

It is preferable that this solid acid is pulverized into powder and then uniformly dispersed in the ink.Since the ink is in the form of a gel with viscoelasticity, the solid acid in powder form is mixed into the crosslinked structure of the ink. It is well retained and does not cause non-uniform dispersion due to sedimentation.

The solid acid made of metal oxide used in the present invention includes:
Aj! 203. ZnO, TiO2, CeO2.

Single oxides such as As2O3, V2O5, Cr2O3, MoO3, or SiO2-Al2203. B2O3
-Ajl! 203゜Cr2O3-AA 203, M
oO3-AA 2o3. ZrO2-3i02.

Ga203-8i02, Be0-3i02, M
gO-3i02.

CaO-3i02.5rO-8i02. Y2O3-
3i02゜La2O3-8i02, 5n02-3i0
2, PbO-8i02.

Composite oxides such as MgOB2O3 and T102-ZnO can be used. The above solid acids may be used alone or in combination of two or more.

The solid acid is preferably contained in an amount of 0.1 to 20%, more preferably 0.6 to 10% by weight, based on the total amount of the ink. If the content of the solid acid is less than 0.1% by weight, it will not have a sufficient effect on stabilizing the pH value of the ink, and if a large number of sheets are printed, the pH value of the ink will increase and the ink will deteriorate. It hardens, resulting in poor film formability. On the other hand, if the content exceeds 20% by weight, the fluidity of the ink will deteriorate, resulting in poor film-forming properties.

Further, in order to disperse the solid acid, it is also possible to use a known dispersing machine such as a roll mill or a kneader-attritor.

The image recording ink of the present invention includes the above-mentioned liquid dispersion medium,
The ink contains a crosslinked structure substance and a solid acid made of a metal oxide, and if necessary, a coloring agent made of dyes and pigments or colored fine particles, a coloring compound that develops color when energized, or a desired ink. An electrolyte that imparts conductivity and enables the ink to conduct electricity, and if necessary, a fungicide,
It may contain additives such as preservatives.

As the above-mentioned colorant, dyes and pigments that are generally used in the fields of printing and recording, such as carbon black, can be used without particular restrictions, but liquid dispersion media on the transfer medium (when not energized) can be used. From the viewpoint of suppressing coloring due to adhesion 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 per 100 parts of liquid dispersion medium.
It is preferable to use at least 1 part, more preferably 1 to 30 parts (especially 1 to 10 parts).

As the coloring agent, colored fine 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 preferable from the viewpoint of suppressing the transfer of the liquid dispersion medium to the transfer medium or the suppression of coloration when no current is applied.

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), per 100 parts of the liquid dispersion medium.
It is preferable to use Generally, when the fine particle size is increased, it is desirable to increase the fine particle content in the ink from the viewpoint of coloring property.In addition, in the present invention, the toner particles are used regardless of their electrophotographic properties such as chargeability. It is possible to do so.

The particle size of the pigment or colored fine particles as the coloring agent mentioned above is as follows:
0.01 μm to 100 μm1 and even 0.01 to 20 μm
It is desirable that

If this particle size is less than 0.01 μm, pigment particles, etc. will cross-link if the ink comes into contact with the intermediate transfer medium or recording material (when not energized) and a slight amount of the liquid dispersion medium is transferred to the intermediate transfer medium, etc. The particles are not held in the structure and are transferred together with the liquid dispersion medium, which tends to cause image fogging.Furthermore, if the particle size exceeds 100 μm, the resolution is insufficient for normal images.

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 substance (if necessary, a crosslinking agent, a coloring agent, an electrolyte, etc.) are uniformly mixed while heating. After preparing a viscous solution or dispersion, it may be cooled to form a gel.

In addition, when adding a basic component for the purpose of adjusting the pH of the ink, NaOH, KOH, NaCO3 and other strong,
A weak base may be added as appropriate.

Also, for the purpose of adjusting the conductivity of the ink when energy is applied, NaCl! , LiCjl! , KCl and other salts 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, water and a water-soluble organic solvent may be used for the purpose of preventing drying of the ink, maintaining wettability, etc. Mixtures are also preferably used.

Examples of water-soluble organic solvents include methyl alcohol,
Alkyl alcohols having 1 to 4 carbon atoms such as ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, 5eC-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; Ketones or keto alcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; N-methyl-2-pyrrolidone, 1,
Nitrogen-containing heterocyclic ketones such as 3-dimethyl-2-imidazolidinone; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, 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 method of applying electricity will be explained.

When applying a pH change to ink using an electrode, this pH value change occurs in the depth direction of the ink (current flow direction).
Because the ink is selectively diffused (unlike three-dimensional diffusion such as heat), it is possible to clarify the ink pattern (breakage, improve image quality).

In addition, when recording by <pH value change based on energization, an elution phenomenon of the electrode due to electrolysis occurs at the anode. Therefore, when using an inert metal such as platinum as the recording electrode, Preferably used for materials. In such a case, fine processing such as photolithography is required, and costs tend to be relatively high due to the use of EB (electron beam) evaporation or sputter evaporation.

On the other hand, when the recording electrode is a cathode, it is preferable because it does not require microfabrication of the anode, which enables cost reduction.

Inks that enable recording with such a cathode include:
An ink consisting of a peptide compound such as a protein and a dispersion medium containing water, whose pH (when the pH remains unchanged) is
A compound whose H value is higher than the isoelectric point of the peptide compound (toward the alkaline side) (by adding an aqueous alkaline solution or the like) is preferably used.

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

The gel-like ink 2 of the present invention is carried while being supported on the surface of the ink transfer roll 1 as the ink transfer roll 1 rotates in the direction of arrow A. This transported ink 2
An ink reservoir 3 is formed by a coating roll 4 rotating in the direction of arrow E, and the ink 2 stored in this ink reservoir 3 forms an ink layer controlled to a constant thickness on the surface of the ink transfer roll 1. be done.

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 grounded by the earth wire 11, thereby forming an ink image 2a in which the ink 2 is selectively adhesive. The ink image 2a is further conveyed in the direction of arrow A and reaches a position where the layer made of ink 2 comes into contact with the intermediate transfer roll 6 rotating in the direction of arrow B. At least a portion of the ink 2 constituting the ink layer formed on the ink layer 1) is transferred onto the intermediate transfer roll 6 to form the ink pattern 2b.

Ink pattern 2 formed on this intermediate transfer roll 6
b is transferred as the roll 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. It is conveyed in the direction of the arrow by 9c and 9d.

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 10, and a new ink pattern 2b is transferred again.
used for the formation of

Meanwhile, at the ink transfer position, the intermediate transfer roll 6
The ink image 2a' and the fluid ink 2 that have not been transferred are further transferred in the direction of the arrow A, separated from the intermediate transfer roll 6 by the action of gravity (based on their non-adhesive properties), and placed in the ink reservoir 3. and be made available again based on its liquidity.

The ink image 2a' returned to the ink reservoir 3 and the fluid ink 2 are agitated by the rotation of the ink transfer roll in the A direction and the rotation of the coating roll 4 in the E direction.
It becomes a uniform component, is layered again to a constant thickness, and recording can be repeated according to the same process.

In the ink pattern forming step described above, that is, the step in which the ink pattern 2b is formed by selectively transferring the ink 2 to the intermediate transfer roll 6, at the separation position between the intermediate transfer roll 6 and the ink layer, the ink layer is Such a shearing force is rather a negative value. Therefore, the intermediate transfer roll 6
Although the circumferential speed of the ink transfer roll 1 may be constant relative to the circumferential speed of the ink transfer roll 1, it is possible to apply a shearing force to the ink layer based on the difference in the circumferential speed. This is preferable from the viewpoint of stabilizing the peeling off from the intermediate transfer roll 6.

It is presumed that this ink 2 does not qualitatively transfer the liquid dispersion medium to the crosslinked structure material.・Also, since electrical energy is used as an image signal, fluid ink 2
If, for example, guar gum or polyvinyl alcohol is cross-linked with boric acid ions as the cross-linked material, the amount of current required to destroy (at least part of) this cross-linked structure is as follows. Only the amount necessary to transfer electrons to and from the crosslinking agent (for example, the borate ions mentioned above), which is usually added to the ink in a very small amount (for example, about several hundred ppm to the ink), 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, as shown in FIG. 4, a plurality of electrode elements 5b made of metal such as platinum or gold are provided on a base 5a. 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 portion where the recording electrode is formed.

As the electrode element 5b, one formed by electroless platinum plating is preferably used from the viewpoint of adhesion to the base material 5a and durability.

In the configuration shown in FIG. 1, electricity is applied between the recording electrode 5 and the ink roll 1, but electricity may also be applied between the recording electrode 5 and the intermediate transfer roll 6. Current may be passed between the plurality of upper electrode elements 5b.

In the above, the embodiment of the present invention has been mainly explained in which the ink is in a gel state in a broad sense and is selectively turned into a sol state by electricity to impart tackiness. By making it acidic), it is made into a sol state that is sticky or sticky when no current is applied, and for example, by applying electrochemical energy, it may be selectively put into a gel state (non-sticky) to form an ink pattern.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Example 1] After uniformly dissolving the above components while heating them to 80 to 90°C, 3 g of silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) and silica-alumina (manufactured by JGC Chemical Co., Ltd., manufactured by JGC Chemical Co., Ltd.) as a solid acid were added. After adding 3 g of N633HN, l!20328 wt%) and thoroughly dispersing it, 2.5 g of a solution of sodium tetraborate IO hydrate (Na2B407 ・10H20) dissolved in 20 wt% propylene glycol was added. After gelation, 0.3 g of IN sodium hydroxide was added dropwise and mixed to obtain a gel-like ink.

Take a part of the ink of Example 1 and place it on top of this in a 5cm
Gently place a 5cm piece of aluminum foil on it and leave it at a temperature of 25℃.
After leaving the aluminum foil in an atmosphere at 60% room temperature for 1 minute, the aluminum foil was gently peeled off from the ink surface and the aluminum foil was accurately weighed. There was virtually no increase in the weight of the aluminum foil (weight increase). (0.1g or less).

The gel ink thus obtained was applied to the recording apparatus shown in FIG. 1, and an image formation test was conducted.

That is, referring to Fig. 1, a stainless steel 40 m
An ink transfer roll 1 consisting of a cylindrical roll (surface roughness 100S) with a diameter of mφ and an intermediate transfer roll 6 consisting of a cylindrical roll made of iron (40 mmφ) whose surface is plated with hard chrome are arranged with a gap of 1 mm at the ink transfer position. The gel ink 2 of the present invention obtained as described above was charged into the ink reservoir 3 of the image recording apparatus shown in FIG.

When the ink transfer roll 1 was rotated in the direction of arrow A at a rotation speed of about 1 Orpm to form a layer of ink 2 on the roll 1, it was found that the 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.

The intermediate transfer roll 6 (30 mmφ) was rotated at a rotation speed of about 13 rpm in the direction of arrow B while contacting the layer formed on the ink transport roll 1 in this manner. At this time, when electrical energy was not supplied from the recording electrode 5 to the layer of ink 2, a very small amount of moisture was transferred onto the intermediate transfer roll 6, but the ink 2 was substantially transferred onto the intermediate transfer roll 6. It was not transferred to

On the other hand, the area of the recording electrode 5 having the shape shown in FIG.
m m
When the pulse c was applied, the ink 2 was selectively transferred onto the intermediate transfer roll 6, and the ink pattern 2b was transferred.

At the ink image transfer position, the recording paper 8 made of plain paper is transferred to the intermediate transfer roll 6 in the direction of the arrow.
A pressure roll 7 (10 m long on a 20 mmφ iron cylindrical roll) rotates at the same speed as the intermediate transfer roll 6 in the direction of arrow C.
When the sheets (with a silicone rubber layer of m thickness
A cyan dot image 2C (with a size of 1 mm) was obtained.

The transferred recorded image 2C obtained on the recording paper 8 was a high-quality image with no trailing or fogging (and high image density).

In addition, the above-mentioned recording by energization (the width of the image is 50 m
m, of which the area ratio of the image actually printed is 5
0%) (repeatedly) to evaluate changes in image density and resolution.As a result, 297 mm x 52,5
Even after printing on 300 sheets of cut plain paper (equivalent to A4 size) in the longitudinal direction, there was no change in image density or resolution compared to the initial printing.

[Example 2] An ink was prepared in the same manner as in Example 1, except that silica-magnesia (manufactured by Tsukagel Honsho Hakutosha) was used instead of the silica-alumina used in Example 1, and the same experiment was carried out. I did it. the result,
As in Example 1, good image quality was obtained even after printing 300 sheets.

[Example 3] Silica-alumina (N633HN) used in Example 1
: manufactured by JGC Chemical Co., Ltd., AA20328% by weight) instead of silica-alumina (N633L, manufactured by JGC Chemical Co., Ltd.).

An ink was prepared in the same manner as in Example 1, except that 13% by weight of A1203) was used, and the same experiment was conducted. As a result, as in Example 1, good image quality was obtained even after printing 300 sheets.

[Example 4] Instead of the solid acid and silica-alumina used in Example 1, silica-magnesia (E53J1, manufactured by JGC Chemical Co., Ltd.) was used.
An ink was prepared in the same manner as in Example 1, except that the following was used, and the same experiment was conducted. As a result, as in Example 1, 3
Good image quality was obtained even after printing 00 sheets.

[Comparative Example 1] An ink was prepared in the same manner as in Example 1 except that silica-alumina was not contained in Example 1, and image recording was performed under the same conditions. As a result, the image quality after recording 300 sheets had a lower image density than the initial image (even compared to Example 1, the image quality was lower).

〔Effect of the invention〕

As described above, according to the present invention, an image recording ink capable of recording at extremely low running cost is provided by eliminating the need for a high-cost ink ribbon having a solid ink layer (conventionally used). Ru.

By using the image recording ink of the present invention, you can easily
The recording cost is significantly lower than that of the thermal transfer recording method, and it also enables image recording that eliminates the disadvantages of the inkjet method, such as nozzle clogging, blurring, trailing, and fogging of the recorded image, resulting in poor image quality.

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 transferability of the ink is also good, it is possible to significantly reduce costs in terms of energy consumption.

Further, by using the image recording ink of the present invention, even if printing is performed on a large number of sheets in succession, the gel state of the ink does not change, making it possible to perform stable printing.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a recording device using the image recording ink of the present invention, FIG. 2 is a perspective view of the device shown in FIG. 1, and FIGS. 3(A) and (B) are viscoelastic FIG. 4 is a perspective view showing an example of a recording electrode used in the image recording device.

Claims (1)

[Claims] (1) An image recording ink that includes a liquid dispersion medium and a crosslinked structure substance that holds the liquid dispersion medium, and that can be imparted with tackiness by applying electricity, and contains a solid acid made of a metal oxide. An image recording ink characterized by: