JPH02130183A - Image recording ink - Google Patents

Abstract

PURPOSE:To continuously form a stable and satisfactory image by incorporating nonhygroscopic solvent as liquid dispersing medium. CONSTITUTION:Liquid dispersing medium containing crosslinking structure substance for holding the medium to control adhesive properties by conduction includes nonhygroscopic organic solvent. The organic solvent which satisfies nonhygroscopic and nondrying conditions includes, for example, triacetin. The content of the organic solvent is 10-60% to total amount of ink. However, it contains hygroscopic solvent for obtaining adhesive controllability by conduction as liquid dispersing medium in addition of the organic solvent. The hygroscopic solvent includes, for example, methyl alcohol, ethyl alcohol, n-propylene alcohol, isopropylene alcohol, etc. The crosslinking structure substance includes, for example, vinylalcohol-vinyl acetate copolymer having 10 to 70mol% of saponification value. The copolymer can desirably hold the nonabsorptive solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image recording ink whose tackiness can be controlled by applying electricity.

[Background Art] 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, daim 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. Ink jets have low consumable costs, but because they eject low-viscosity liquid ink from thin nozzles, clogging due to solidification of the ink may be unavoidable when not in use. Furthermore, since the ink used for inkjet is a low viscosity ink, depending on the type of paper, after the ink is transferred to the paper, it tends to bleed and blur the image.

The thermal transfer method is a method in which patterned heat is supplied to a layer of solid ink provided on a sheet-like support to melt the ink and transfer it to plain paper or the like. This thermal transfer method is characterized in that a relatively small-sized device is used and the cost of the device 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.

Therefore, as a new image recording method that eliminates the above drawbacks and enables low running cost recording, for example, Japanese Patent Laid-Open No. 63
-30279, JP-A-63-71386, etc. were proposed.

The image recording method described in these documents uses a fluid ink that has fluid film-forming properties but is substantially non-adhesive and can be imparted with adhesive property by applying energy, and is applied to an ink carrier. a step of forming a layer of the fluid ink on the ink, supplying energy in a pattern according to the image signal to the ink calendar, and transferring the fluid ink imparted with tackiness according to the pattern onto the transfer medium. This is an image recording method characterized by comprising a transfer step of: This image recording method can eliminate the drawbacks of other image recording methods as described above.

That is, the noise and the like that occur in the impact printer described above do not occur in this method. Furthermore, this method is more advantageous in terms of equipment cost than electrophotographic equipment.

In addition, there is no need for the high-cost ink ribbons and ink sheets that are essential in conventional thermal transfer methods, and the ink that is not actually used for image recording can be reused, which is advantageous in terms of consumable costs. . Moreover, unlike the inkjet method, there is no need to always take measures against deterioration in image quality due to nozzle clogging, blurring of recorded images, and the like.

[Problem to be solved by the invention]

In the image forming method that controls the tackiness of the ink by applying energy as described above, the fact that the content of the liquid dispersion medium in the ink is difficult to change makes it possible to continuously form stable and good images and improves the environmental resistance of the ink. It is important in terms of stability, storage stability, etc.

For example, if the content of the liquid dispersion medium is higher than necessary,
The tackiness of the ink increases, and the transfer of the non-current-carrying portion to the non-transfer medium may reach a level that cannot be ignored in practice, resulting in a decrease in image quality.

Conversely, when the content of the liquid dispersion medium decreases,
The electrical resistance of the ink may increase and the density of the resulting image may decrease. Furthermore, if the ink dries and solidifies, it becomes impossible to replenish the liquid dispersion medium, making it impossible to form a film.

An object of the present invention is to provide an image recording ink that is more suitable for use in the image forming method as described above, and in particular, an image recording ink that is excellent in that the content of the liquid dispersion medium is difficult to change. It is about providing.

[Means to solve the problem]

That is, the present invention provides an image recording ink that contains a liquid dispersion medium and a crosslinked structure material that holds the liquid dispersion medium, and is capable of controlling tackiness by applying electricity, wherein the liquid dispersion medium is a non-hygroscopic organic solvent. An image recording ink characterized by containing:

Since the ink of the present invention contains a non-hygroscopic organic solvent, the content of the liquid dispersion medium is stabilized.

This is because conventional image recording inks generally use water and a hygroscopic solvent that easily absorbs moisture in the air as the liquid dispersion medium, but the ink of the present invention This is because, since a non-hygroscopic organic solvent (such as triacetin) is used instead of a non-hygroscopic solvent (such as propylene glycol), it becomes difficult to absorb moisture in the air, that is, it becomes difficult to increase the content of the liquid dispersion medium. In other words, the present inventors found that it is extremely important to include a non-hygroscopic organic solvent in order to improve the stability of the liquid dispersion medium content without impairing the tackiness controllability and film-forming properties of the ink when energized. They found that it is suitable for

As the non-hygroscopic organic solvent for the ink of the present invention, it is preferable to use a non-hygroscopic organic solvent having a boiling point higher than water, such as triacetin or octylene glycol, from the viewpoint of stability of the content of the liquid dispersion medium. It is even more preferable. This is because a liquid dispersion medium having a boiling point of water or lower may evaporate in a high-temperature environment, resulting in a decrease in the liquid dispersion medium content of the ink.

The ink of the present invention is disclosed in Japanese Patent Application Laid-Open No. 63-30279 mentioned above.
It can be used very suitably for the image recording method described in Japanese Patent Application Laid-open No. 63-71386, and has low running costs that eliminates the drawbacks of impact printers and thermal transfer methods, and provides clear images. An image forming method that can obtain an image can be performed more favorably. Note that this is particularly advantageous for continuous printing.

Hereinafter, the present invention will be described in detail with reference to the drawings as necessary. In addition, in the following description, the quantitative ratio is 1%.
” and “parts” are based on weight unless otherwise specified.

The image recording ink of the present invention is an ink whose tackiness can be controlled by energization 6 In other words, it has substantially tackiness when energized (or when energized) and when energized (or when not energized). is an ink that is given tackiness. Further, it has a fluid film formability to the extent that it can be formed into a layer on a carrier. Note that "substantially adhesive" means exhibiting non-adhesiveness to the extent described below, for example.

Place a 5cm x 5cm square on the surface of the fluid ink in the container.
After weighing the aluminum foil carefully (after weighing it accurately) and leaving it for 1 minute in an atmosphere with a temperature of 25℃ and a humidity of 60%,
The aluminum foil is gently peeled off from the ink surface, and the aluminum foil is 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 on the order of 0 to 1000 mg (or even 0 to 100 mg). preferable.

The above-mentioned ink having better film-forming properties and adhesion control properties is, for example, an ink having a gel state in a broad sense in which the liquid dispersion medium is held by a cross-linked structure substance, but this gel-like ink further contains particles (with a particle size of Preferably 0. old to 100-1
More preferably 0. An ink obtained by dispersing 20 μm in diameter may also be used.

Each component contained in the ink of the present invention will be explained in more detail below.

The ink of the present invention contains a non-hygroscopic organic solvent as a liquid dispersion medium. In addition, in the present invention, "non-hygroscopic" means
This does not only mean the property of not absorbing moisture in the air at all, but also includes cases where it absorbs a small amount of moisture to the extent that it does not adversely affect image formation.Also, as mentioned earlier, it has a higher boiling point than water. (Non-drying) It is preferable to use a non-hygroscopic organic solvent.

Particularly, triacetin (also known as glyceryl triacetate) can be mentioned as an organic solvent that suitably satisfies the above-mentioned non-hygroscopic and non-drying conditions. However, other than that, various non-hygroscopic organic solvents such as octylene glycol can also be used.

The content of the above non-hygroscopic organic solvent is based on the total amount of ink.
It is 10% to 60%, preferably 25% to 50%. However, if only a non-hygroscopic organic solvent is contained as a liquid dispersion medium, it is usually impossible to control the tackiness of the ink by applying electricity. Therefore, in addition to the non-hygroscopic organic solvent, it is necessary to contain a solvent (water, a hygroscopic solvent) as a liquid dispersion medium in order to ensure adhesion controllability by energization.

When a hygroscopic solvent is included to ensure adhesion controllability by energization, examples of the hygroscopic solvent include methyl alcohol, ethyl alcohol, n-propylene alcohol, isopropylene alcohol, n-butyl alcohol, and 5ec-butyl. Alkyl alcohols having 1 to 4 carbon atoms such as alcohol, tert-butyl alcohol, and isobutyl alcohol; amides such as dimethylformamide, dimethylacetamide, N-methylacetamide, N-methylformamide, and N-methylpropionamide;
Ketones or ketoalcohols such as acetone and diacetone alcohol; Nethenes such as tetrahydrofuran and dioxane; Nitrogen-containing heterocyclic ketones such as N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone: Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; polyalkylene glycols such as butylene glycol, triethylene glycol, 1,2,6-hexandriol, thioglycol, hexylene glycol, and diethylene glycol, in which the alkylene group has 2 to 6 carbon atoms. Alkylene glycols containing: glycerin; lower alkyl ethers of polyhydric alcohols such as ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl (or ethyl) ether; amines such as nitriethanolamine; etc. Examples include sterile solvents.

These can be used alone or in combination of two or more. The content of the hygroscopic solvent must be such that the hygroscopicity of the ink does not pose a practical problem, and although it varies depending on the type of solvent, it is 25% or less, preferably 10% or less, based on the total amount of the ink.

In addition, when using a non-hygroscopic organic solvent and water together, the ratio (non-hygroscopic solvent: water) = (9:1) to (4:6) is desirable, and (7:3) to (,5 :5) is preferred. Furthermore, when a non-hygroscopic organic solvent and a hygroscopic solvent are used together, the ratio is (non-hygroscopic organic solvent: hygroscopic solvent) = (+0
0: 0.1 ) to (75 to 25) is desirable, and (10
〇21) to (90:10) are preferred.

The "crosslinked structure substance" contained in the ink of the present invention refers to a substance that can form a crosslinked structure by itself, or a substance that can form a crosslinked structure by itself, or a substance that can be formed by adding other additives (for example, a crosslinking agent made of inorganic ions such as borate ions). , refers to a substance that is capable of forming a crosslinked structure. The "crosslinked structure" refers to a three-dimensional structure having "crosslinked bonds." This "bridge 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). The above-mentioned "crosslinked structure" is sufficient as long as it can obtain the desired liquid dispersion medium retention property.

That is, this crosslinked structure may be, for example, a network, honeycomb, or spiral structure, and may not be a regular structure.

The crosslinked structure substance contained in the ink of the present invention is a polymer compound, particularly a hydrophilic (natural or synthetic) polymer, etc.
It is preferable to use a material that can also retain a non-absorbable organic solvent well, and a particularly preferred one is one that has a degree of saponification of 1O
Examples include vinyl alcohol-vinyl acetate copolymers of mol% or more and 70 mol% or less, preferably 20 mol% or more and 55 mol% or less. The present inventors discovered for the first time that this copolymer is excellent in that it can retain non-absorbable solvents well.

The vinyl alcohol-vinyl acetate copolymer is polyvinyl acetate [the following general formula (a)]]+-CH2-CH+-
.=(a) A copolymer obtained by saponifying C0CL [the following general formula (b)] 0)10COCH3. The degree of saponification means ×100 (1,000m+1%). If the copolymer has a low degree of saponification of less than 10 mol %, the number of hydroxyl groups for forming a crosslinked structure will decrease, which is not preferable.

On the other hand, if the above-mentioned copolymer has a high degree of saponification exceeding 70 mol %, it becomes difficult to dissolve in the above-mentioned non-hygroscopic organic solvent, which is not preferable.

The crosslinked structure substance used in the present invention can form a crosslinked structure by itself, for example, based on its properties as a polymer. A crosslinking agent (or gelling agent) may be used to crosslink more actively.

Ionic crosslinking agents include various salts of diboric acid such as CuSO4: NazB40t, NaB(OH)4,
NaJz04, NaBO□, JOa, KJ204
, KJ4(h, BO, etc.) can be suitably used.

When these ionic crosslinkers are used, electrochemical reactions (
This is preferable from the viewpoint of suppressing pattern energy consumption because it becomes easy to impart selective tackiness to the ink by transferring electrons (electron transfer and receiving) or by changing the pH. These ionic crosslinking agents are used in an amount of 0.05 to 100 parts of the crosslinked structure material.
It is preferable to use 3 parts (and even 1 to 1.5 parts of O).

Examples of covalent crosslinking agents include glyoxal and dialdehyde benzene.

If the ink of the present invention is desired to have a desired color tone, dyes and pigments that are generally used as colorants in the fields of printing and recording can be suitably used. These colorants may be used by being dissolved or dispersed in the ink. This colorant is
The content is preferably 0.5 to 20% based on the weight of the entire ink.

In addition, when adding a basic component for the purpose of adjusting the pH of the ink, triethanolamine, NaOH1 and OH
, NazCO, and other strong/weak bases may be added as appropriate.

Furthermore, for the purpose of adjusting the conductivity of the ink, LiBF4.
Salts such as NaCl, LiCl, KCI, etc. may be added.

Further, a pH stabilizer such as an ionic surfactant may be added for the purpose of stabilizing recording by continuous energization.

Further, fine powder fillers such as silica and carbon black may be added as appropriate for the purpose of adjusting the viscoelasticity of the ink.

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 vinyl alcohol and borate ions is bonded to the OH group of the vinyl alcohol, the crosslinking structure changes. The liquid dispersion medium is electrolyzed by the borate ion CH2 in the vicinity of the anode of electricity (or addition of an electron pair acceptor such as hydrochloric acid), and the pH value of the liquid dispersion medium changes to the acidic side. It is presumed that this is because electrons were taken away, the crosslinked structure (at least a part of it) was destroyed, and selective tackiness was imparted to the ink.

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

CH.

(Sol) 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 as the pH decreases, sol formation occurs. progresses.

The image recording ink of the present invention includes the above-mentioned liquid dispersion medium,
A crosslinked structure substance (if necessary, a crosslinking agent, a coloring agent, an electrolyte, etc.) is mixed uniformly with heating to form a viscous solution or dispersion medium, and then cooled to form a gel.

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, an example of an image forming method using the ink of the present invention will be described. FIGS. 1 and 2 are a sectional view and a perspective view showing the configuration of an apparatus for forming the image.

The gel-like ink 2 of the present invention is carried while being supported on the surface of the ink transfer roller 1 as the ink transfer roller 1 rotates in the six directions of the arrows. This transported ink 2
An ink reservoir 3 is formed by a coating roller 4 rotating in the direction of arrow E, and the ink 2 stored in this ink reservoir 3 forms an ink layer with a controlled thickness on the surface of the ink transport roller 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 roller 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 six directions of the arrows, and reaches a position where the intermediate transfer roll 6 rotating in the direction of the arrow B contacts the layer made of the ink 2. At least a portion of the ink 2 constituting the ink layer formed on the intermediate transfer roller 6 is transferred onto the intermediate transfer roller 6 to form an ink pattern 2b.

Ink pattern 2 formed on this intermediate transfer roller 6
b is transferred as the roller rotates in the direction of arrow B, and is transferred onto the recording paper 8 by a transfer roller ruff rotating in the direction of arrow C at the ink image transfer position, forming a transferred recorded image 2c.

The transferred recorded image 2c thus formed on the recording paper 8 is conveyed together with the recording paper 8 by transport rollers 9a, 9b and 9c,
It is conveyed in the direction of the arrow by 9d.

After the ink pattern 2b is transferred onto the recording paper 8, the ink remaining on the surface of the intermediate transfer roller 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 roller 6
Ink image 2ax and fluid ink 2 that were not transferred to
The ink is further transferred in the direction of the arrow 6, separated from the intermediate transfer roller 6 by the action of gravity (based on its non-adhesive property), returned to the ink reservoir 3, and made available for use again based on its fluidity. Ru.

The ink image 2ax returned to the ink reservoir 3 and the fluid ink 2
The ink is stirred by the rotation of the ink transfer roller in six directions and the rotation of the coating roller 4 in the E direction, and becomes a uniform component, which is again formed into a layer with a constant thickness, and recording can be repeated according to the same process. can.

If the water contained in the ink evaporates significantly during image formation through the above-described process, drop the evaporated amount of water into the ink reservoir 3 and remove the water from the ink transfer roll 1. It is preferable to mix by rotating the coating roll 4.

In the above-mentioned method, when recording is performed based on a change in pH value based on energization, an elution phenomenon of the electrode due to electrolysis occurs at the anode of the electrode. It is preferable to use such inert metals as the recording electrode material. In such cases, microfabrication such as photolithography is required, and EB (,
The cost tends to be relatively high due to the use of electron beam (electron beam) evaporation or sputter evaporation.

On the other hand, when the recording electrode is used as a cathode, the above-mentioned fine processing is not required, so it is possible to reduce the cost of the electrode, which is preferable.

As the recording electrode 5, for example, as shown in FIG.
A plurality of electrode elements 5b made of a metal such as platinum or gold are provided on a base 5a, and an insulating coating 5c made of polyimide or the like is provided on the electrode elements 5b except for the tip (the part that contacts the ink). A recording electrode provided with is preferably used.

In the image forming method described above, unlike three-dimensional diffusion such as heat, electrodes are used to apply pH to the ink.
Since this pH value change is selectively diffused in the depth direction of the ink layer (current flow direction),
The ink pattern can be clarified (cutting and image quality improved).

Further, in the image forming method as described above, a relatively small amount of electrical energy is required as an image signal. For example, when polyvinyl alcohol is cross-linked with borate ions as the cross-linked structure material of the fluid ink 2, it is necessary to The amount of current to be supplied is only the amount necessary to transfer electrons to and from the crosslinking agent (for example, the above-mentioned borate ion) which is normally added to the ink in a very small amount (for example, on the order of several hundred ppm to the ink). This amount of current is approximately 1/1 of the amount of current when using a thermal head.
Since it may be about 0, recording with lower energy consumption can be achieved by utilizing such electrochemical changes.

〔Example〕

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

Example 1 (Ingredient A) (Ingredient B) (Ingredient C) (Ingredient D) "Reethanolamine... 0.5 part The above A component was uniformly dissolved while heating to 80 to 90°C,
After that, add the above B component, mix well, and leave at room temperature (25℃).
Component C was added and mixed well, and Component D was added and gelled to obtain an ink.

Printing was performed using this ink using the recording apparatus shown in FIG. Specifically, a stainless steel cylinder with an outer diameter of 40 mm is used as the ink transfer roller 1, and the ink 2 is transferred by rotating in the six directions of arrows, and coated to a constant thickness by the coating roller 4, which rotates in the direction of arrow E. did.

In this embodiment, the circumferential speed of the ink transfer roller 1 is set to 2 (1
mm/sec, the circumferential speed of coating roller 4 is 24 m
m/sec, and the gap between them was set to 1.0 mm, so that an ink layer with a layer thickness of 1.2 mm was formed on the surface of the ink transfer roller 1.

The intermediate transfer roller 6 has an outer diameter of 30 mm in this embodiment.
A stainless steel cylindrical member is disposed above the ink transport roller 1 with a distance of about 1.0 to 1.2 mm from the surface of the ink transport roller 1, and an ink layer coated on the ink transport roller 1. , and is configured to be rotatable in the direction of arrow B by a driving means.

The platinum electrode shown in Figure 3 was used as the recording electrode.
Recording was performed at a recording voltage of V. As a result, a clear black recorded image could be obtained on plain paper according to the image signal.

Further, this ink was left in a high humidity environment at a temperature of 50° C. and a humidity of 90% for about 10 hours. As a result, due to drying, the total amount of ink slightly decreased by 1.0% compared to before standing. This ink could be coated onto the coating roller 4 to a constant thickness.

Furthermore, after replenishing this ink with the amount of water that evaporated,
When an image was formed in the same manner as described above, a clear black recorded image similar to that described above could be obtained.

On the other hand, when we conducted a similar environmental test in a low-humidity environment with a temperature of 50°C and humidity of 20%, we found that the ink weight was 4.
．． Similar good results were obtained with only a 2% decrease.

Example 2 (Component A) (Component C) (Component D) (Component B) An ink was obtained in the same sequential manner as in Example 1, except that the above-mentioned components were used. Using this ink, recording was performed on plain paper using the same recording apparatus and recording method as in Example 1. As a result, a clear black recorded image could be obtained at a recording voltage of 40 V in accordance with the image signal. In addition, as a result of high humidity and low humidity environment tests similar to those in Example 1,
Good results similar to those of Example 1 were obtained in both coating performance and recording performance.

Example 3 (Component A) (Component B) Ink was obtained by sequential operations. Using this ink, recording was performed on plain paper using the same recording apparatus and recording method as in Example 1. As a result, a clear black recorded image could be obtained at a recording voltage of 40 V in accordance with the image signal. Further, as a result of performing the same high humidity and low humidity environmental tests as in Example 1, good results similar to those in Example 1 were obtained in both coating performance and recording performance.

Comparative example 1 (component A) (component C) (component D) (component B) Same as Example 1 except that each of the above components was used. (component C) Comparative example 2 (component A) Above Uniformly dissolve component A while heating it to 80 to 90°C,
After that, add the above B component, mix well, and leave at room temperature (25℃).
The mixture was cooled to a temperature of 100.degree. C., and component C was added thereto to form a gel, thereby obtaining an ink.

Using this ink, recording was performed on plain paper using the same recording apparatus and recording method as in Example 1. As a result, it was possible to obtain a clear black recorded image according to the image signal at a recording voltage of IOV.

Further, this ink was left in a high humidity environment with a temperature of 50° C. and a humidity of 90% and a low humidity environment with a temperature of 50° C. and a humidity of 20% for about 10 hours. As a result, in both cases, the ink dried and solidified due to evaporation of water in the ink, making it impossible to coat the ink. It was also impossible to replenish water.

(Component B) (Component C) The above component A is uniformly dissolved while heating to 80 to 90°C,
After that, add the above B component, mix well, and leave at room temperature (25℃).
The mixture was cooled to a temperature of 100.degree. C., and component C was added thereto to form a gel, thereby obtaining an ink.

Using this ink, recording was performed on plain paper using the same recording apparatus and recording method as in Example 1. As a result, it was possible to obtain a clear black recorded image according to the image signal at a recording voltage of IOV. In addition, this ink was exposed to a high temperature environment of 50℃ and humidity of 90%, and a temperature of 50℃ and humidity of 2.
It was left in a low humidity environment of 0% for about 10 hours. As a result, in a high humidity environment, the weight of the ink increased by 7% due to moisture absorption. An attempt was made to coat this ink to a constant thickness on the coating roller 4 and apply a voltage by bringing the recording electrode 5 into contact with the ink surface, but the contact of the electrode 5 greatly disturbed the ink surface and the recording failed. It was impossible. On the other hand, in a low humidity environment, the ink dries and hardens.
It was not possible to coat the coating roller 4 with a constant thickness. However, 1% for this ink
When water was replenished, coating became possible and recording performance returned to its original state.

evaluation: The above results are summarized in Table 1 below.

In addition, in the table, conting property is "fair".
Indicates that it is possible to coat to a constant thickness, and "impossible" indicates that it is not possible. Further, "good" head contact property indicates that the ink surface is not disturbed by contact and recording can be performed, and "poor" indicates that the ink surface is disturbed and recording cannot be performed. Further, the recordability after water replenishment being "fair" indicates that it is possible to record with the ink soaked in water, and "replenishment not possible" indicates that the ink cannot be dried and solidified to contain water.

As is clear from the results shown in Table 1, in Comparative Example 1, since the ink contained only water as a liquid dispersion medium, it dried and solidified in the high-humidity and low-humidity environment tests; It is also impossible to replenish water. Furthermore, in Comparative Example 2, since the content of the hygroscopic solvent as the liquid dispersion medium is high, the tackiness increases more than necessary in the high-temperature environment test and the head contactability deteriorates.

On the other hand, in Examples 1 to 3, there was no such problem,
It was also possible to form good images in high humidity and low humidity environment tests.

Example 4 Ink preparation, image formation, and environmental testing were performed in the same manner as in Example 1, except that the triacetin content was changed to 5 parts, and the same good results as in Example 1 were obtained. .

Example 5 Example 1 except that the triacetin content was 45 parts.
Ink preparation, image formation, and environmental tests were conducted in the same manner as in Example 1, and the same good results as in Example 1 were obtained.

Example 5 Ink preparation, image formation, and environmental testing were conducted in the same manner as in Example 1, except that 20 parts of octylene glycol was used instead of triacetin, and the same good results as in Example 1 were obtained. was gotten.

[Effects of the Invention] As explained above, since the ink of the present invention contains a non-hygroscopic solvent as a liquid dispersion medium, the content of the liquid dispersion medium in the ink is difficult to change, and therefore it has a stable and good quality. This ink has excellent environmental resistance and storage stability, allowing continuous image formation.

The ink of the present invention is an ink that can be very suitably used in an image forming method that utilizes tack control by energization (an image forming method that eliminates the drawbacks of impact printers, thermal transfer methods, and the like).

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a recording device in which the image recording ink of the present invention is used, FIG. 2 is a perspective illustration thereof, and FIG. 3 is an example of the recording electrode shown in FIGS. FIG. 1... Ink transfer roller 2... Ink 2a... Ink image 3...
... Ink reservoir 4 ... Coating roller 5
... Recording electrode 5b ... Electrode element 6 ... Intermediate transfer roller 7 ... Transfer roller 8 ... Recording paper

Claims (1)

[Scope of Claims] 1) An image recording ink that contains a liquid dispersion medium and a crosslinked structure material that holds the liquid dispersion medium, and that enables tackiness to be controlled by applying electricity, wherein the liquid dispersion medium is a non-moisture-absorbing ink. An image recording ink characterized by containing a synthetic organic solvent. 2) The crosslinked structure substance has a saponification degree of 10 mol% or more 70
2. The image recording ink according to claim 1, which contains a vinyl alcohol-vinyl acetate copolymer in an amount of mol % or less. 3) The image recording ink according to claim 1 or 2, wherein the non-hygroscopic organic solvent contains triacetin.