JP3292061B2 - Image forming method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for electrochemical deposition / deposition using a dispersion liquid in which coloring material fine particles are dispersed in an aqueous solvent.
The present invention relates to a method and an apparatus for forming an image by an adhesion phenomenon.

[0002]

2. Description of the Related Art When an image is formed, a high image quality (1000
In order to aim at DPI level resolution / color reproduction / multi-value gradation), the image thickness is preferably 2 μm or less, more preferably, from the relationship between the color reproduction range and the image sharpness. It is believed to be less than 1 micron in thickness. Accordingly, the average shape diameter of the image forming material, which is an element providing the image structure, needs to be 1 micron or less. In the case of powder having an average shape diameter of 5 μm or less, there is a problem in fluidity. In this regard, powder based image forming materials are considered to be quite difficult to use, while liquid based image forming materials are considered to be effective. Representative examples of the latter image recording technology include a silver salt technology, an ink jet technology, and a liquid developing electrophotographic technology.

1) A printing technique using silver halide is described in Hatsumi Tanemura et al., "High-quality color copy system using silver halide photography."
Japan Hardcopy '89 Research Proceedings P229, etc. 2) The printing technology using electrophotographic technology of liquid development,
E. FIG. B. Caruthers, et al. , "Mod
eling of Liquid TonerElec
tritical characters "P
rosedings of IS & T 10th I
nt @ l. Congress on Advances
in Non-Impact Printing T
technologies P204 (# 94), etc. 3) Usui is a printing technology using inkjet technology.
Minoru "Development of New Method MACH" Japan Hardco
py'96 There are many technical presentations such as the research presentation proceedings P161.

The following method is known as a prior art which is considered to be closer to the present invention in which an image is formed using a liquid.

4) An image forming method using an electrodeposition liquid in which a coloring material is dispersed in an insulating liquid to generate an electric double layer (Japanese Patent Application Laid-Open No. 7-181750, Japanese Patent Publication No. 7-54407), A method for forming a fine pattern and an electrodeposition offset printing method using an electrodeposition printing technique in which an insulating pattern is provided on a printing plate to form an insulating pattern (JP-A-4-9902, JP-A-6-293)
125).

5) Electrodevelopment method. For example, it is shown in Proceedings of the Society of Electrophotography Society of Japan P32 (1971) and Proceedings of the Society of Electrophotography Society of Japan P24 (1964.11). In the electrolytic development method, reduction of zinc oxide is caused by application of a voltage of 10 V or more and simultaneous exposure, and electrons generated thereby move to a dye precursor dissolved in a color developing solution and are reduced. This is a method of forming an image by depositing and coloring on the surface of a zinc oxide film.

[0007]

Among the conventional printing techniques, the printing technique 1) using a silver salt has no problem in image quality or image fastness, but has a chemical reaction due to a printing process involving a chemical reaction. The use of highly active chemicals and waste has led to problems with office adaptation.

[0008] In the ink jet printing technique 2), it is difficult to obtain a high resolution due to the problem of nozzle diameter and printing reliability.
Further, since the image forming material is generally an aqueous dye, there are problems in image fastness, safety and printability on plain paper.

Electrophotographic technology 3) using an insulating liquid developer has no problem in image quality, printability on plain paper, and image robustness comparable to printing, but the machine size increases due to the complicated printing process. Problems with safety and reliability. Further, the safety of the developing solution due to the solvent vapor of the hydrocarbon solvent is regarded as a major problem, and in some cases the use is severely restricted by the government.

The conventional electrodeposition printing technique, in which an insulating pattern is provided on a conductive substrate and used as a printing plate, involves complicated processes such as forming a non-image portion of an insulating resist in advance by a photolithography process. For this reason, it is difficult to change the image pattern every time to perform printing, and the accuracy of the apparatus is high, the scale is large, the number of processes is large, and the amount of waste is large. Therefore, it can be used only when it is installed in a well-equipped factory for printing. Further, the history of the image forming process is likely to remain on the substrate, and the reproducibility of fine image recording is low. In addition, since the image portion is concave, the image portion also has poor fluidity of particles, weakens particle deposition / adhesion selectivity, and a large amount of image forming material liquid component in the image portion tends to remain. For this reason, the viscosity becomes low, and the image forming material in the image area is liable to cause flow and cohesive failure in the transfer step, and it is difficult to obtain high image quality.

The conventional printing technique 5) using an aqueous dye solution as the electrodeposition solution has no problem with the vapor of the organic solvent, and has a few tens of angstroms because the minimum pixel unit is a dye molecule order.
There is no problem with the high resolution because it is sufficiently small as the unit, but the image part is mainly composed of a water-soluble dye,
Problems remain in safety (prevention of suction into the human body) and high optical density of images.

As described above, not only the above technology 1) but also the technologies 2) to 5) have characteristics required for the image forming technology used in the office (that is, 1000 DPI or more / multi-level gradation color high image quality, Possibility of printing on plain paper, image robustness comparable to printing, high security of printed records and printing machines, almost no waste, low running cost, small quantity Characteristics such as the possibility of making prints easily and inexpensively) are not completely satisfied.

Thus, the present invention provides image quality, image robustness,
An object of the present invention is to provide an image forming method which is excellent in safety and an image forming apparatus therefor.

It is another object of the present invention to provide an image forming method and an image forming apparatus for the same which consume little energy, consume less energy, and have simple processes and equipment.

Another object of the present invention is to use a printing plate,
An object of the present invention is to provide an image forming method and an image forming apparatus for the same that can be adapted to print production of small lots and many kinds.

In short, a main object of the present invention is to provide an image forming method and an image forming apparatus for realizing various characteristics required for an image forming technique used in an office.

[0017]

The image forming method of the present invention, which can achieve the above object, comprises a colorant fine particle having a dispersant adsorbed thereon.
Child A colorant particle dispersion prepared by dispersing in an aqueous liquid,
When the pH value of the dispersion is anodic deposition,
PH value between +1 and +3 compared to the starting pH point
Set and start deposition when the dispersion is cathodic deposition
Set to a pH value between -3 and -1 compared to the pH point
An image holding member that can function as one of an electrode pair and has a surface for holding an image, and a counter electrode that is the other of the electrode pair is immersed in the colorant fine particle dispersion liquid thus obtained. The step of preparing, and applying a voltage of less than 10 V between a desired portion of the image holding member and a counter electrode that is the other of the electrode pair, the desired portion of the image holding member and the counter electrode are dispersed with the dispersion liquid. And the pH of the colorant fine particle dispersion
By changing the value, the dispersion stability of the color material fine particles is changed, and the color material fine particles are electrochemically deposited on desired portions thereof.
Depositing to form an image.

The operation will be described with reference to FIG. 1 which schematically shows a typical example of the image forming method of the present invention.

When a voltage is applied to the image holding member 11 using an auxiliary electrode 12 (an electrode connected to a power source V; hereinafter also referred to as a cooperative electrode) in contact with a part of the image holding member 11, image holding is performed. A portion of the member 11 substantially corresponding to the auxiliary electrode 12 functions as one of the counter electrodes (the image holding member 11
Of the image holding member 11 via the colorant fine particle dispersion liquid 15 in which the ionized colorant fine particles 13 are dispersed in the aqueous liquid 14.
Between the corresponding portion and the counter electrode 16 is in a conducting state. Thereby, in the portion corresponding to the auxiliary electrode of the image holding member 11,
The ionized color material fine particles 13 are attracted to the polarity opposite to the polarity, deposited and adhered to form an image. Note that the auxiliary electrode 12 is not essential, since a voltage may be directly applied to the image holding member 11 without using the auxiliary electrode 12.

In the method of the present invention, since a liquid is used for image formation, fine particles of color material having a size of 1 micron or less can be used as a color material of the image forming material. Therefore, high image quality (1
000 DPI / multi-valued gradation or more), and a pigment-based coloring material can be used. Therefore, the coloring material has high image density, high optical density, and safety not to be taken into the human body. I can be satisfied.

Further, since an aqueous liquid is used as the liquid to be used, the safety is high from this point as well.

Further, a printing plate is unnecessary, and image information can be generated by inputting an image signal each time printing is performed. Therefore, it is possible to easily and inexpensively produce prints of various kinds in small quantities.

The energy consumption is small, the process and equipment are simple and simple, so the running cost is low and there is almost no waste.

In the image forming method of the present invention, a step of forming an image by transferring the image forming material deposited on the image pattern portion on the surface of the image holding member to a recording medium may be further carried out. In this case, print output is possible on the plain paper surface.

According to the above method, there is provided a container for containing a colorant fine particle dispersion in which ionized colorant fine particles are dispersed in an aqueous liquid, and a container which is set in the container and which can function as one of an electrode pair and which is capable of functioning as an image. This can be performed by an image forming apparatus including an image holding member having a surface for holding the image and a counter electrode that is the other of the pair of electrodes.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to embodiments.

In a typical embodiment of the image forming method of the present invention, first, a colorant particle dispersion in which ionized colorant particles are dispersed in an aqueous liquid is prepared.

The ionization of the coloring material fine particles is achieved with the aid of a reagent (a dispersant described later). The ionized coloring material fine particles referred to in the present invention refers to particles in a state in which a dispersant is adsorbed by the coloring material fine particles, and does not include a dye that ionizes itself and dissolves in an aqueous liquid. Any color material that can be dispersed in a fine particle state with a reagent (dispersant) may be used, so that there is an advantage that a wide range of color material particles can be used. In the process of forming an image, the coloring material fine particles and the reagent thereof contribute.

Dyes and pigments having little or no solubility in water and oil-soluble dyes are suitable as the coloring material fine particle material. In addition, disperse dyes, dye lake pigments, and resins containing pigments in resins It is also possible to use powder or the like.

Examples of the above-mentioned dyes and pigments include inorganic pigments such as carbon black, titanium oxide, zinc white, red iron oxide, alumina white, aluminum powder, bronze powder, and the like.
Zinc oxide, barium sulfate, magnesium carbonate, ultramarine,
For example, toluidine red, permanent cumin FB, fast yellow-G, disazo yellow-AAA, disazo orange PMP, lake red C, brilliant cumin 6B, and the like.
Phthalocyanine Bull, Indanthromble, Quinacridone Red, Dioxazine Violet, Victoria Viewable, Alkaline Toner, Aniline Black, Permanent Red 2B, Barium Lysole Red, Quinacridone Magenta, Naphthol Red HF4
B, phthalocyanine line, benzimidazolone red and the like.

Examples of oil-soluble dyes include Victoriaable-4R base, nigrosine, nigrosine base,
C. I. Solvent Yellow 19,
C. I. Solvent Orange 45, C.I.
I. Solvent Red8 and the like.

The average particle size of the coloring material fine particles is generally from 0.01 μm to 1.0 μm, preferably 0.06 μm.
From 0.3 to 0.3 μm. When the average particle diameter is below the range, the light-shielding property of the image layer is reduced, so that the optical image density is apt to be reduced, the gloss is generated more than necessary in the image, and a problem is liable to occur in the safety. When the average particle diameter is larger than the above range, the dispersion state of the dispersion of the coloring material fine particles becomes poor, causing a problem in the uniformity of the image layer containing the coloring material fine particles and the occurrence of unnecessarily matted images. Is easy to occur. When the thickness is less than 0.06 μm, the dispersibility is excellent, but the optical density tends to be low.
μm to 0.3 μm is preferred.

The aqueous liquid in which the coloring material fine particles are dispersed includes water and any solvent which has an affinity for water and can be recognized as a water-soluble solvent in the chemical field (eg, methanol, ethanol, butanol). , Alcohols such as isopropyl alcohol, ketones such as acetone and methyl ethyl ketone, ethanol
Amines such as dimethylamine, dimethylamine, and triethanolamine, and acids such as acetic acid, sulfuric acid, phosphoric acid, oxalic acid, and phthalic acid). One of these may be used alone, or a mixture of two or more thereof may be used. Is suitable. Particularly, a mixed solvent containing water as a main component is very useful in terms of safety, stability and cost. It should be noted that addition of a water-insoluble solvent to an aqueous liquid is acceptable in the present invention as long as the desired effects of the present invention can be exerted.

In order to obtain the dispersion stability of the coloring material fine particles, and to cause the coloring material fine particles to generate and / or maintain a stable dispersion or ionized state which causes the phenomenon of deposition and adsorption of the coloring material fine particles on the image holding member. A dispersant is added to the colorant fine particle dispersion. The dispersion liquid is a substance having electrical properties that is adsorbed (by binding, adhesion, association, or the like) on the surface of the coloring material fine particles and stabilizes the dispersion of the coloring material fine particles. In addition, if necessary, various additives such as a wetting material, a water-soluble polymer material, an emulsion material, a latex material, and various kinds of solvent may be added. For the sake of convenience, these will be specifically described after describing the essential steps of the method of the present invention.

The composition of the colorant fine particle dispersion (hereinafter, also simply referred to as dispersion) has a solid content of usually 1 to 40% by weight, preferably 5 to 18% by weight.
It is. If the solid content concentration is less than 1% by weight, there is a possibility that problems such as difficulty in obtaining the dispersion stability of the color material components and difficulty in easily obtaining the optical density of the image. Also 4
When the solid content concentration is higher than 0% by weight, the liquid tends to be non-uniform at the time of image formation, and the liquid exhibits thixotropy, which causes problems such as complicated handling of the liquid.

In the solid component of the dispersion, the amount of the coloring material component in the solid component is usually from 30% by weight to 80% by weight.
Preferably it is from 40% by weight to 60% by weight. If the value is lower than the above range, the gloss of the image becomes too high or the optical density of the image is reduced. On the other hand, when the value is higher than the above range, the particle deposition efficiency is reduced, defects and defects are liable to be formed in the image layer, the fixing strength is lowered and the color tone is liable to be problematic.

The volume resistivity of the dispersion is usually 10 ⁵ Ω ·
cm ³ or less, preferably 10 ³ Ω · cm or less. If the value is higher than the above range, the voltage for depositing the coloring material is increased, the foaming phenomenon of the electrode is activated, or the depositing phenomenon becomes unstable, and the film quality of the coloring material is likely to vary.

The viscosity of the dispersion is from 1 cps to 1000 cp.
s is good, more preferably from 10 cps to 200
cps range. When the value is lower than the above range, the liquid is liable to be insufficiently viscous, so that the droplets are easily scattered. On the other hand, when the value is higher than the above range, a problem such as a decrease in efficiency due to an increased operation load in the transportability and stirring of the dispersion liquid may occur.

In the dispersion, the dispersion stability of the coloring material fine particles usually changes due to a change in pH. For example, as shown in FIG. 2, a system (curve 1) which is alkaline and has a stable dispersion of the coloring material, and has a clear tendency to settle on the acidic side (curve 1) can be suitably used in the present invention. , A system that tends to have high dispersibility (curve 2) or a system that tends to have high sedimentation (curve 3)
Are not suitable for the present invention. This is because, at the time of energization in the subsequent image forming step, the pH of the dispersion liquid generally fluctuates, and this causes the coloring material to precipitate.

In the setting of the pH of the dispersion, when the dispersion is the anodic deposition method, the pH value of the dispersion is +
PH value between 0 and +4 [that is, pH value to (pH +
4) Value], more preferably +1 to + from the pH point
Set to a pH value between +3 values. In addition, when the dispersion is a cathode deposition method, the pH is -4 to
Set to a pH value between 0, more preferably from -3 to
When the pH of the dispersion is set to a pH value between −1, high deposition film formation efficiency is maintained. Outside the above range, setting the precipitation range pH beyond the precipitation start pH point causes inconveniences such as the dispersion stability of the dispersion liquid not being obtained and the precipitation of the coloring material fine particles in the non-image area or the variation in the precipitation amount. is there. Setting the pH range outside the above-mentioned range, which is beyond the preferred set pH range, is difficult to deposit, resulting in low deposition film formation efficiency, raising the deposition potential and causing problems in the film properties of the formed film.

After preparing the colorant fine particle dispersion as described above, the dispersion contains an image holding member which can function as one of the electrode pairs and has a surface for holding an image.
The counter electrode, which is the other of the pair of electrodes, is immersed. This is used in the next step as an image forming apparatus.

The form and material of the image holding member are not particularly limited as long as the functions described above are exhibited. For example, as the material, such as metal, organic semiconductor, inorganic semiconductor,
A substrate having conductivity, a substrate obtained by depositing these on an insulating substrate, or the like can be used. In particular, noble metals such as platinum and gold, and carbon are preferable because of their excellent electrochemical stability. Further, a transparent substrate such as ITO or a conductive polymer formed on a transparent substrate such as glass or a transparent film can be used as an image holding member.

A substrate having a conductive surface and a photoconductive material (typically, P
(N junction or PIN junction). This is because, by light irradiation, an electromotive force is generated in the irradiated portion, and as described in detail later,
An electric current flows in the light-irradiated portion of the image holding member, and the electrodeposited phenomenon of the dispersed particles occurs in that portion, so that optical writing is possible. The whole substrate may have conductivity, or only the surface thereof may have conductivity.

As a material for forming the PN junction or the PIN junction, a p-type semiconductor and an n-type semiconductor are joined,
Any type can be used as long as the type semiconductor and the n-type semiconductor are joined via an insulating layer and have photovoltaic power (photoconductive material).
Each of those materials can be used regardless of organic or inorganic. Typically, Si, Ge, GaAs, inorganic photoconductive materials are used.
CdSe, CdS, CdTe, InP, AlSb, Ga
P and the like. Examples of organic photoconductive materials include phthalocyanines having various central metals, porphyrins, naphthalocyanines (p-type), perylene derivatives such as perylene, perylenetetracarboxylic diimide, and benzimidazole perylene (n-type), and polyvinyl. A wide variety of materials such as carbazole [PVK] (p-type), quinacridones (p-type), and polyphenylenevinylene [ppv] (n-type) can be used.

An undoped (non-doped) semiconductor is generally used for the insulating layer. P of amorphous silicon
In the case of IN junction, n-type amorphous silicon
About 50 nm, i-type amorphous silicon 500 to 10
About 00nm, p-type amorphous silicon 10-50n
A film thickness of about m is preferred. In the case of an organic PN junction, since the conductivity is low and the absorption is large, each of the P layer and the N layer
A film thickness of about 100 nm is preferred.

As the image holding member, those having a high smoothness on the surface on which an image is formed and having no step can obtain good printing characteristics.
In particular, this characteristic becomes important when a repeated image holding member is used. As a result, the physical cleaning property of the image on the image holding member surface is enhanced, and a printing cycle in which the history of the previously recorded image information is not always left even when the particle deposition recording of a different image is performed every time can be constructed.

The counter electrode, which is the other of the pair of electrodes, is not particularly limited in its material and shape. For example, the material is Pt,
It may be selected from general-purpose ones used in the electrochemical field, such as Au, SUS, and carbon.

The image holding member and the counter electrode are immersed in a colorant fine particle dispersion.
At least a portion of the object is not only literally immersed in the liquid, but also includes contact with the liquid surface.

It should be noted that the image holding member and the counter electrode are naturally provided with a means for conducting a current therebetween. for that reason,
Normally, the image holding member is directly connected to a conducting wire through which a current flows when used, or an auxiliary electrode (cooperating electrode) as described above is contacted or installed, and the conducting wire is connected thereto. . However, when the conducting wire is not connected to the image holding member, the cooperating electrode is formed in a needle shape or a pen shape, and when the cooperating electrode is brought into contact, the image holding member can function as an electrode. Is also good.

In consideration of stabilization of the voltage between the image holding member and the counter electrode, it is practically preferable to use a three-electrode system having a control electrode in addition to these electrodes.

After the above-mentioned apparatus is prepared, a desired portion of the image holding member and a counter electrode are energized via a dispersion. As a result, the coloring material fine particles are electrochemically deposited on the desired portion, and an image is formed. This is because if the color material particles are ionized to the positive side, the image holding member can function as a cathode, so that the color material particles can be deposited on the cathode, while the color material particles are ionized to the negative side. For example, by causing the image holding member to function as an anode, color material fine particles can be deposited on the anode.

In general, an external power supply may be used to supply current between the image holding member and the counter electrode. In this case, unless the resistance value of the image holding member is made too small (for example, less than 1 kΩ), the cooperating electrode having a needle shape, a pen shape, or the like is scanned with respect to the image holding member, and thereby the lower portion of the cooperating electrode is scanned. Only the surrounding image holding member portion functions as an electrode, and the portion is energized, so that an image of a desired pattern can be drawn. Note that, in this case, the image holding member has a conductive layer that, when a current is input from the back surface, the current is output without the input signal being diffused from the surface holding the image.

When the image holding member uses a photoconductor, the above-mentioned energization can be performed by irradiating light or by using light irradiation and application of a bias voltage. is there. In this case, an image of a desired pattern can be drawn by imagewise exposure or scanning with irradiation light such as a laser.

FIGS. 3 to 6 schematically show an example of an apparatus for performing such a process. In the device shown in FIG.
The dispersion liquid 15 is put in the inside, and the counter electrode 16, the image holding member 11,
The control electrode 18 (immersed in the dispersion) is used (the same applies to the apparatus shown in other drawings), the counter electrode 16 is sunk horizontally in the dispersion 15, and the image holding member 11 is leveled. The surface for holding the image is in contact with the dispersion surface. An imagewise exposure device 19 is installed on the image holding member 11.

In the apparatus shown in FIG. 4, a container 10 having an opening on the side is used, and the image holding member 11 is set in close contact with a sealing jig (not shown) so as to close the opening, and is opposed to the image holding member 11. The counter electrode 16 is set vertically, and its lower part is immersed in the dispersion liquid 15. Further, an imagewise exposure device 19 is provided to face the image holding member 11.

In the apparatus shown in FIG. 5, a container 10 having an opening on the bottom is used, and the image holding member 1 is closed so as to close the opening.
1 is set in close contact with the counter electrode 1
6 is set horizontally and immersed in the dispersion 15.
A laser light source 20 and a laser scanning system 22 such as a polygon mirror 21 are arranged opposite to the image holding member 11.
A desired portion of the image holding member 11 can be scanned by a laser.

In the above-described apparatus, light is radiated imagewise or beam-like light is scanned, so that the conductivity of only a desired portion of the image holding member 11 is increased. An energized state occurs between the counter electrode 16 and the counter electrode 16 via the dispersion liquid 15. As a result, the color material 13 is deposited on a desired portion of the image holding member 16 to form an image.

In the apparatus shown in FIG. 6, the counter electrode 16 is set horizontally near the bottom of the container 10 and is immersed in the dispersion liquid 15. The image holding member 11 is fixed by an image holding member fixing jig 23 so that the surface on the image holding side contacts the liquid surface of the dispersion liquid 15. Image input print head 2
A needle-shaped cooperating electrode 4 is provided so as to be able to contact and scan the back surface of the image holding member 11 by the print head scanning system 25.

In this apparatus, the image input print head 24 is scanned by the print head scanning system 25 and, when desired, comes into contact with the image holding member 11 and the contact between the contact portion of the image holding member 11 and the counter electrode 16. Becomes energized, and as a result,
The color material 13 is deposited on the back surface of the contact portion of the image holding member 11 to form an image.

As described above, according to the present invention, a current is applied or an electric field is formed in the image holding member 11 corresponding to the image pattern, and a color material is deposited on the portion to form an image. .

Hereinafter, the conditions of the image forming (particle deposition) step will be specifically described. The voltage difference applied between the image holding member and the counter electrode in this step is determined by using a bias voltage.
Usually, it is less than 15V. However, in order to sharply reproduce each pixel on the image, a short-time DC pulse and a signal input of the short pulse by a heavy chest may be performed. The voltage difference applied between both electrodes is preferably less than 10 V using a bias voltage, and within 5 V if more importance is attached to the film properties of the coloring material. When a voltage difference of 10 V or more is applied, the generation of bubbles due to the electrolysis of the dispersion liquid from the electrode surface in the liquid becomes severe, the electric field distribution on the electrode surface becomes uneven, and the film quality of the deposited film itself becomes uneven. Also, the surface of the deposited film tends to be uneven, and it tends to be difficult to reproduce a fine pattern image.

In the known electrodeposition coating, generally, an applied voltage of 50 V or more is applied to perform electrodeposition. This is because if the applied voltage is low, the resistance of the electrodeposited film generated is high, and as the electrodeposited film formation proceeds, the electrodeposited film formation speed is greatly reduced and the required film thickness cannot be obtained. A high voltage is applied to cause an intense foaming phenomenon due to electrolysis, which is used to agitate the vicinity of the electrode surface and bring the electrode surface into contact with a new electrodeposition solution, thereby obtaining a film thickness required for electrodeposition coating (generally 10 μm). Above). However, the object of the method of the present invention is to reproduce a high-quality image, and it is preferable that a fine image pattern having a film thickness level of 1 μm or less can be reproduced. Therefore, the foaming phenomenon due to electrolysis of the dispersion is suppressed. And even if it occurs, a fine image pattern
Must be kept at a level that does not affect reproduction. As a result, the applied voltage difference is a DC electric field of less than 10 V, and if the image quality is more important, a DC electric field of 5 V or less.

In order to maintain the uniformity of the liquid property of the dispersion bath,
Stirring in the dispersion bath facilitates formation of a uniform deposited film. However, too strong agitation must be avoided because it may delay the formation of the deposited film or cause the dispersion liquid to scatter.

By controlling the temperature of the dispersion, more uniform and good film properties can be obtained. Since the precipitation phenomenon itself is affected by the liquid temperature, it is recommended to install a high-precision liquid temperature control system especially when obtaining high-quality image reproduction.

The image pattern formed on the image holding member by the method described above can directly handle the image holding member as a document, or can transfer an image to another medium and handle it as a document (transfer). Will be specifically described later).

Next, the above-mentioned dispersant and the like will be described in detail. The dispersant generally has hydrophilicity and the presence of a molecular structure having a group that is easily ion dissociated in an aqueous liquid in order to fulfill its function (dispersion function of the coloring material fine particles). And when a current or an electric field is provided to the dispersion,
Usually, the pH of the dispersion near the current supply section of the image forming surface of the image holding member is changed, and the electric double layer formed by the dispersant wrapping the particles near the image current supply section of the image holding member is compressed, and the color is changed. Agglomeration of the fine particles of the material occurs, causing their precipitation phenomenon.

When the image portion (image pattern portion) of the image holding member is electrically anodic from the counter electrode, the dispersing agent may be a structural material having at least one anionic group represented by the following structure. One or more may be utilized. When these are bonded, adhered or associated with the surface of the coloring material fine particles, a precipitation phenomenon in a preferable state occurs, and a coloring material deposited film as a particularly high quality image is obtained. In particular, those in which the anionic group is a carboxyl group have a good colorant fine particle deposition efficiency in the precipitation phenomenon and show better characteristics.

[0068]

Embedded image

When the image area of the image holding member is electrically cathodic rather than the counter electrode, one or more structural materials having at least one cationic group represented by the following structure are used as the dispersant. Can be done. These are bonded to the surface of the coloring material fine particles,
Due to the attachment or association, a precipitation phenomenon in a preferable state occurs, and a color material deposition film as a particularly high quality image is obtained.

[0070]

Embedded image

In particular, the above-mentioned surfactant having an ionic substituent, a water-soluble polymer and a polymer having a low degree of polymerization show particularly good characteristics in terms of dispersion stability and film properties of a deposited film. Examples of these dispersants having a water-soluble polymer and a polymer having a low degree of polymerization include alkyl alkylene oxide carboxylate, alkyl oxide carboxylate, alginic acid-modified carboxylate, carboxy-modified methyl cellulose, and polyacryl. Examples include acid-modified carboxylate, polymethacrylic acid-modified carboxylate, polyethylene oxide-modified carboxylate, epoxy-modified carboxylate, polyethanolamine-modified methylcellulose, amine-modified alginate, and amine-modified polyacrylic. .

The wetting agent mentioned above is added for the purpose of preventing the deterioration of the dispersion due to the evaporation of the aqueous solvent component. Its properties and form are such that it is highly hydrophilic, has an azeotropic point with water and has a high boiling point. A low vapor pressure liquid is preferred. The required properties include a highly polar solvent, preferably a boiling point of 120 ° C.
Above, the saturated vapor pressure at room temperature in the atmosphere is 100 mmHg or less,
More preferably, the vapor pressure in the atmosphere at a boiling point of 150 ° C. or more is 6
0 mmHg or less. If the ratio is outside the above range, the life of the dispersion is shortened, and the characteristics of the dispersion are largely changed, so that it is difficult to obtain stable deposition characteristics. The composition ratio is preferably in the range of 0.5 wt% to 70 wt%, and more preferably in the range of 5 wt% to 30 wt% in the liquid component of the dispersion. Typical specific examples thereof include ethylene glycol, diethylene glycol, polyethylene glycol, glycerin, triethanolamine, methylcellosolve, ethylcellosolve, butylcellosolve, and ethylene glycol diacetate.
And so on.

Water-soluble polymer additives, electrolytic polymer materials,
The addition of emulsion materials (other than the colorant fine particle dispersion) allows them to be deposited, for example, as part of the image during image formation, to provide stable deposition properties during particle deposition and to improve the film properties of the deposited film. This has a great effect on the robustness of the deposited image and the control of the electric resistance of the film. The amount of these additives is preferably in the range of 0.2 wt% to 50 wt%, and more preferably in the range of 1 wt% to 15 wt%, as the concentration in the solid content.

As the water-soluble polymer additive, gelatin,
Gum arabic, pectin, casein, starches, microcrystalline cellulose, alginate, polyvinyl alcohol,
Representative examples include vinyl acetate copolymers, polyacrylic acid copolymers, and methylcellulose derivatives.

Typical examples of the electropolymerized material include pyrrole, phenylene, diacetylene, aniline, thiophene, and derivatives thereof.

As the emulsion material, polyvinyl acetate emulsion, vinyl acetate copolymer emulsion,
Acrylic ester copolymer emulsions and synthetic rubber latex are typical examples.

In addition, an antiseptic / antifungal agent, a trace amount of a surfactant, a pH adjuster, a liquid viscosity adjuster, and the like are added as necessary. Particularly, since the aqueous liquid is liable to be deteriorated due to propagation of microorganisms and generation of mold, it is particularly preferable to add an antiseptic / antifungal material.

Next, a method for transferring an image formed on the image holding member to another medium will be described. In this transfer, the image formed by the precipitation phenomenon on the image holding member is transferred from the image holding member using electrostatic force, pressure, adhesive force, chemical bonding force, etc., and the image is transferred to a transfer medium such as plain paper. Perform formation. The specific method can be performed, for example, by bringing a transfer medium into contact with the image holding surface of the image holding member and pressing the transfer medium with a pressure roller.

The image carrier on which an image has been formed can also be used as a master (original) for forming a duplicate image. For example, through a step of applying a water-soluble dye to the entire surface of an image carrier on which an oil-soluble image is formed, a water-soluble dye is attached only to a non-image portion, and the water-soluble dye is transferred to another recording medium. This allows the image to be duplicated.

The method of the present invention can be carried out continuously by using, for example, an apparatus schematically shown in FIG.

In this apparatus, a counter electrode 16 is provided inside the bottom surface of the container 10 in which the dispersion liquid 15 is placed, and two rollers 70 and 71 are arranged in the dispersion liquid 15 at an interval. In addition, two rollers 72 and 73 are arranged on the upper part in parallel with the roller pair, and the four rollers
A belt-shaped image holding member 11 is wound around the belt. The image holding member 11 has a configuration in which a photoconductive substance is laminated on a transparent substrate via a transparent electrode. A transfer roller 74 is pressed against one of the upper rollers 72, and a sheet 76 from a sheet roll 75 can be conveyed therebetween. A cleaning brush 77 is in contact with the other 73 of the upper roller, and a cleaning waste tray 78 is provided below the cleaning brush. Further, the imagewise exposure device 19
Is provided so as to be able to irradiate light downward around the center of the belt formed by the image holding member 11.

In this apparatus, when a voltage is applied between the image holding member 11 and the counter electrode 16 by a power supply (not shown) while exposing by the imagewise exposure device 78, the image holding member 1
An image of the color material 13 is formed on the first color. Next, the image is transferred to the sheet 76 by the transfer roller 74 around the image holding member 11. Further, when the image holding member 11 is rotated, the cleaning brush 77 removes unnecessary color material particles remaining on the image holding member 11, and the portion of the image holding member 11 is brought into a state where it can be used again for image formation. You.

The color material particles on the surface of the image holding member 11 can be removed by a cleaning method such as a blade method, a fur brush method, an elastic roller method, a cleaning web method, or an air knife method. Used.

[0084]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. Example 1 Carbon black (coloring material) powder (average particle size 0.1 μm)
m) 10 parts by weight, diethylene glycol (wetting agent) 15
Parts by weight, 3 parts by weight of sodium polyoxyethylene alkyl ethercarboxylate (dispersant), 3 parts by weight of sodium polyethylene glycol dicarboxylate (dispersant), 6 parts by weight of water-soluble acrylic resin (additive), isopropanol (Solvent) 7 parts by weight, 55 parts by weight of distilled water, and the above materials were mixed, and a medium-strength propeller was stirred for 1 hour to sufficiently wet the carbon powder to form a coarse dispersion. Next, the dispersion liquid was subjected to a high-intensity forced dispersion treatment for 3 minutes using a homogenizer-dispersing machine to prepare a dispersion stock solution. 120 parts by weight of distilled water, 10 parts by weight of glycerin, 0.8 parts by weight of a fungicide (Proxel XL-2, ICI),
Was added dropwise to this dispersion stock solution while stirring with a propeller to complete a colorant fine particle dispersion solution. This solution was adjusted to pH 6.5 by adjusting the pH with a phosphoric acid aqueous solution and a sodium hydroxide aqueous solution. The pH of this liquid at the starting point of the precipitation of the coloring material fine particles was 5.0. The volume resistivity of this liquid was 8 × 10 ² Ω · cm.

Next, as shown in FIG. 3, an image signal can be input from the back surface, and the image holding member functioning as an electrode is placed in a dispersion bath containing the dispersion so that the back surface goes out of the dispersion bath. After setting, a counter electrode and a control electrode using a salt bridge were set in the bath. This image holding member is formed by a laminated structure (a 50 nm-thick two-layer structure of phthalocyanine and perylene pigments) on which a transparent conductive layer of ITO is provided on a glass plate substrate having a thickness of 4 mm, and two organic photoconductor layers are provided thereon. IT
The O-conductive layer is used as a work electrode (refers to a portion to which an external voltage is directly applied in the image holding member functioning as an electrode), and the surface of the organic photoconductive layer can be made smooth without any steps. I was Each electrode was connected to a potentiostat power supply. Then, while inputting an image to the optical image input section on the back surface of the image holding member, a potentiostat power supply applies a 3.0 V D.V. between the work electrode and the counter electrode. C. Voltage was applied for 15 seconds.

Next, the image holding member on which the image formation was completed was taken out of the liquid, and it was confirmed that a high quality image having an optical image density of 1.41 was formed on the surface of the image holding member. Example 2 Carbon black powder (average particle size 0.07 μm) 20
Parts by weight, 10 parts by weight of polyethylene glycol, 5 parts by weight of ammonium polymethyl acrylate dicarboxylate,
5 parts by weight of ammonium polyoxyethylene alkylphenylcarboxylate, 6 parts by weight of water-soluble acrylic resin, 10 parts by weight of isopropanol, 50 parts by weight of distilled water, and the above materials were mixed and stirred with a medium-strength propeller for 3 hours. -The Bon Black powder was sufficiently wetted with a liquid to form a coarse dispersion. Next, this dispersion liquid was subjected to a dispersion treatment for 24 hours using a ball mill disperser to prepare a dispersion stock solution. 200 parts by weight of distilled water, 20 parts by weight of glycerin, fungicide (IC
A diluent obtained by mixing 0.5 parts by weight of Proxel XL-2 (Company I) was dropped into this dispersion stock solution while stirring with a propeller to complete a colorant fine particle dispersion solution. The pH of this solution was adjusted with a phosphoric acid aqueous solution and an ammonia aqueous solution,
The pH was set to 6.0. The pH of this liquid at the starting point of the precipitation of the coloring material fine particles was 5.0. The volume specific resistance of this liquid was 2 × 10 ² Ωcm.

Next, using an apparatus similar to that of the first embodiment shown in FIG. 3, an image holding member provided with a work electrode to which an image signal can be input from the back side is placed in a dispersion containing the above dispersion. The bath was placed with the backside out of the dispersion bath, and a counter electrode, a control electrode utilizing a salt bridge, was placed in the bath. This image holding member is made of a 2 mm thick quartz substrate provided with a transparent conductive layer of ITO on which a two-layer organic photoconductor layer is laminated (as before), and the ITO conductive layer is used as a work electrode. The surface of the organic photoconductor layer was made smooth. Each electrode was connected to a potentiostat power supply. Then, while inputting an image to the optical image input section on the back surface of the image holding member by using He-Ne laser light, a potentiostat power supply applies a 5.0 V D.V. between the work electrode and the counter electrode. C. A pulse voltage (pulse width 2 ms / pulse period 3 ms) was applied.

Next, the image holding member on which the image formation was completed was taken out of the liquid, and it was confirmed that a high quality image having an optical image density of 1.52 was formed on the surface of the image holding member. Example 3 10 parts by weight of phthalocyanine powder (average particle size 0.2 μm), 10 parts by weight of ethyl cellosolve, 7 parts by weight of lithium polyoxyethylene alkylphenylacetate, 4 parts by weight of lithium polymethyl acrylate dicarboxylate, water-soluble 6 parts by weight of an acrylic resin, 10 parts by weight of isopropanol, 50 parts by weight of distilled water, and the above materials were mixed, and a medium-strength propeller was stirred for 0.5 hour to sufficiently wet the pigment powder into a liquid to obtain a coarse dispersion. It was created.

Next, this dispersion liquid was subjected to a dispersion treatment for 4 minutes using a homogenizer-dispersing machine to prepare a dispersion stock solution.
200 parts by weight of distilled water, 20 parts by weight of diethylene glycol, fungicide (Proxel XL-2, ICI) 0.5
By weight, the diluted liquid mixture of parts by weight was dropped into this dispersion liquid while stirring with a propeller to complete a dispersion of coloring material fine particles for electrodeposition. This solution was adjusted to pH 7.0 by adjusting the pH with a phosphoric acid aqueous solution and a lithium hydroxide aqueous solution.
The pH of this liquid at the starting point of the precipitation of the coloring material fine particles was 4.0. The volume resistivity of this liquid was 9 × 10 ² Ωcm.

Next, using the apparatus shown in FIG. 6, an image holding member capable of inputting a current image signal from the back side is placed in a dispersion bath containing the above-mentioned dispersion so that the back comes out of the dispersion bath. Then, a counter electrode and a control electrode using a salt bridge were set in the bath. This image holding member was provided with a 5 mm-thick conductive layer in which current diffusion was suppressed, and the surface of the conductive layer in contact with the liquid was made smooth.

Then, each electrode is connected to a control power source, and an image is input to the image input section on the back side of the image holding member using a 600 DPI needle-type cooperating electrode image input print head, and the image is input to the needle-type cooperating electrode. A 4.0 V D.D. C. A pulse voltage (pulse width 2 ms / pulse period 3 ms) was applied in synchronization with the scanning speed of the print head.

Next, the image holding member having completed the image formation was taken out of the liquid, and it was confirmed that a high-quality image of cyan optical image density 1.53 was formed on the surface of the image holding member. Further, the voltage between the needle-type cooperating electrode and the counter electrode is set to a D.V. of 2.5 V. C. It was confirmed that a high-quality image having a cyan optical image density of 1.10 was formed on the surface of the image holding member by printing with a pulse. Example 4 Carbon black powder (average particle size 0.07 μm) 20
Parts by weight, 10 parts by weight of polyethylene glycol, 5 parts by weight of ammonium polymethyl acrylate dicarboxylate,
5 parts by weight of ammonium polyoxyethylene alkylphenylcarboxylate, 6 parts by weight of water-soluble acrylic resin, 10 parts by weight of isopropanol, 50 parts by weight of distilled water, and the above materials were mixed and stirred with a medium-strength propeller for 3 hours. -The Bon Black powder was sufficiently wetted with a liquid to form a coarse dispersion.

Next, this dispersion liquid was subjected to a dispersion treatment for 24 hours using a ball mill disperser to prepare a dispersion liquid. 200 parts by weight of distilled water, 20 parts by weight of glycerin, pyrrole 4
Parts by weight, fungicide (Proxel XL-2, ICI)
0.5 parts by weight of the mixed diluent was dropped into this dispersion liquid while stirring with a propeller to complete a colorant fine particle dispersion liquid. This solution was adjusted to pH 6.0 by adjusting the pH with a phosphoric acid aqueous solution and an aqueous ammonia solution. The pH of this liquid at the starting point of the precipitation of the coloring material fine particles was 5.0. The volume resistivity of this liquid was 1 × 10 ² Ωcm.

Next, using an apparatus similar to that of Embodiment 1 shown in FIG. 3, an image holding member capable of inputting an image signal from the back surface and functioning as an electrode is placed in a dispersion bath containing the above dispersion. The back side was placed outside the dispersion bath, and a counter electrode and a control electrode using a salt bridge were installed in the bath. This image holding member is made of a 2 mm thick quartz substrate provided with a transparent conductive layer of ITO on which a two-layer organic photoconductor layer is laminated (as before), and the ITO conductive layer is used as a work electrode. The surface of the organic photoconductor layer was made smooth. Each electrode was connected to a potentiostat power supply. While a He-Ne laser beam is used to input an image to the optical image input section on the back surface of the image holding member, a 1.0 V D.V. C. A voltage was applied.

Next, the image holding member on which the image formation was completed was taken out of the liquid, and it was confirmed that a high quality image having an optical image density of 1.26 was formed on the surface of the image holding member. Example 5 (Transfer) In the same manner as in Example 1, a colorant fine particle dispersion was prepared, the image holding member was taken out of the dispersion bath through a recording and printing process, and the image of the dispersed colorant fine particles was placed on the image holding member. Obtained. Plain paper was placed on the surface of the image holding member. A corona discharge of +6 KV is performed from above the paper, and then a pair of rubber rollers is pressed at a linear pressure of 600 g.
/ Cm between the plain paper and the image holding member and pressurized and conveyed. Then, the plain paper immediately after the pressing was peeled off from the image holding member, and a transferred image having an optical image density of 1.33 was obtained on the plain paper. Example 6 (Addition of aqueous emulsion solution) 15 parts by weight of carbon black powder (average particle size: 0.1 μm), 15 parts by weight of glycerin, 5 parts by weight of sodium polyoxyethylene alkyl ethercarboxylate, polyethylene glycol dicarboxylic acid Sodium 3 parts by weight, water-soluble acrylic resin 3 parts by weight, isopropanol 7 parts by weight,
The above materials were mixed with 55 parts by weight of distilled water, and a medium-strength propeller was stirred for 1 hour to sufficiently wet the carbon black powder with a liquid to prepare a coarse dispersion.

Next, this dispersion liquid was subjected to a high-intensity forced dispersion treatment for 3 minutes using a homogenizer-dispersing machine to prepare a dispersion stock solution. A diluent obtained by mixing 100 parts by weight of distilled water, 20 parts by weight of an aqueous solution of vinyl acetate emulsion, and 0.6 parts by weight of a fungicide (Proxel XL-2, ICI) was dropped into the dispersion without stirring with propeller stirring. A colorant fine particle dispersion was completed. This solution was adjusted to pH 6.9 by adjusting the pH with a phosphoric acid aqueous solution and sodium hydroxide. The pH at the colorant fine particle precipitation start point of this liquid was 5.2. The volume resistivity of this liquid is 5 × 10 ² Ωc
m.

Next, as shown in FIG. 3, the image holding member provided with a work electrode to which an image signal can be inputted from the back side is put into a dispersion bath containing the above-mentioned dispersion liquid, and the back side goes out of the dispersion liquid bath. And a control electrode using a salt bridge was installed in the bath. This image holding member is made of a laminated structure (the same as above) of a two-layer organic photoconductor layer on which a transparent conductive layer of ITO is provided on a glass plate having a thickness of 4 mm, and the ITO conductive layer is used as a work electrode. The surface of the organic photoconductor layer was made smooth. Each electrode was connected to a potentiostat power supply. Then, while inputting an image to the optical image input section on the back surface of the image holding member, a 2.5 V D.V. C. Voltage was applied for 15 seconds.

Next, the image holding member after the completion of the image formation was taken out of the liquid, and it was confirmed that a high quality image having an optical image density of 1.42 was formed on the surface of the image holding member.
Next, as a result of performing an eraser rub fixing test, the optical density change amount of this print sample was 0.3. The optical density change amount of the print sample of Example 1 was 0.4. Thereby, it was confirmed that the fixability was improved by the addition of the emulsion aqueous solution. Example 7 (Effect of Particle Size of Coloring Material Fine Particles) Carbon black powder (average particle size 0.1 μm),
Examples using four kinds of pigment powders, carbon black powder (average particle diameter 0.4 μm), carbon black powder (average particle diameter 0.7 μm), and carbon black powder (average particle diameter 2.0 μm) In the same manner as in Example 1, a dispersion was prepared, and a recording and printing evaluation test was performed.

The recording and printing evaluation results show that the optical image density of the recorded image on the surface of the image holding member in the four kinds of dispersion liquids was 1.4.
2, 1.53, 1.25, and 0.76. The dispersion of the carbon black powder having an average particle size of 2.0 μm had unstable dispersion stability, and a precipitate was observed at the bottom of the test tube for sedimentation evaluation after standing for 2 days. Other carbon black pigment powder dispersions were left undisturbed for 2 days, and no sediment was observed at the bottom of the test tube for sedimentation evaluation. Example 8 (addition of wetting agent) 10 parts by weight of carbon black powder (average particle diameter 0.1 μm), 3 parts by weight of sodium polyoxyethylene alkyl ethercarboxylate, 3 parts by weight of sodium polyethylene glycol dicarboxylate, 6 parts by weight of a water-soluble acrylic resin, 7 parts by weight of isopropanol, 70 parts by weight of distilled water, and the above materials were mixed, and a medium-strength propeller was stirred for 1 hour to sufficiently wet the carbon black powder into a liquid. A crude dispersion was made. Next, the dispersion liquid was subjected to a high-intensity forced dispersion treatment for 3 minutes using a homogenizer-dispersing machine to prepare a dispersion stock solution. A diluent obtained by mixing 140 parts by weight of distilled water and 0.3 part by weight of a fungicide (Proxel XL-2 from ICI) was dropped into the dispersion without stirring with a propeller to complete a colorant fine particle dispersion. Was.

Next, as shown in FIG. 3, an image holding member provided with a work electrode capable of inputting an image signal from the back side is placed in a dispersion bath containing the above-mentioned dispersion, and the back side is placed outside the dispersion bath. It was placed out of the way and a counter electrode, a control electrode using a salt bridge, was placed in the bath. Then, while inputting an image to the optical image input section on the back side of the image holding member, a 2.5 V D.V. C. Voltage was applied for 11 seconds.

Next, the image holding member having completed the image formation was taken out of the liquid, and it was confirmed that a high quality image having an optical image density of 1.36 was formed on the surface of the image holding member.
Then, the recording apparatus containing the above-described dispersion liquid of this example and the same recording apparatus containing the dispersion liquid of Example 1 were left as they were for one week. As a result, the liquid level of the recording apparatus of the present embodiment dropped by 25 mm, but the liquid level of the recording apparatus of Example 1 dropped by 9 mm. This indicated that the addition of the wetting agent had an effect on the liquid preservability. Example 9 (pulse voltage application) In the same manner as in Example 2, the same color material fine particle dispersion as in Example 2 was completed.

Next, using the same apparatus as that of the second embodiment shown in FIG. 3, the He-N
While inputting an image with laser light, a potentiostat power supply applies 5.0 V D.P. between the work electrode and the counter electrode. C. Pulse voltage (pulse width 2 ms / pulse period 3 m
s) was applied. At that time, a propeller for stirring was put in the dispersion bath, and printing recording was performed while the dispersion in the bath was slightly stirred.

Next, the image holding member after the completion of the image formation is taken out of the liquid, an image having an optical image density of 1.51 is formed on the surface of the image holding member, and the optical density variation of the solid portion is σ = 0. .05. The optical image density of Example 2 was 1.53, and the optical density variation of the solid portion was σ = 0.09. Example 10 (Liquid Temperature Control) In the same manner as in Example 2, the same color material fine particle dispersion as in Example 2 was completed.

Next, using the same apparatus as that of the embodiment 2 shown in FIG. 3, the He-N
While inputting an image with laser light, a potentiostat power supply applies 5.0 V D.P. between the work electrode and the counter electrode. C. Pulse voltage (pulse width 2 ms / pulse period 3 m
s) was applied. At that time, a temperature controller was put into the dispersion bath, and printing was performed at a constant temperature while controlling the temperature of the dispersion in the bath.

Next, the image holding member having completed the image formation is taken out of the liquid, an image having an optical image density of 1.56 is formed on the surface of the image holding member, and the optical density variation of the solid portion is σ = 0. 0.07. The optical image density of Example 2 was 1.57, and the optical density variation of the solid portion was σ = 0.09. Example 11 (Effect of Preservation by Presence or Absence of Fungicide) 10 parts by weight of carbon black powder (average particle size: 0.1 μm), 15 parts by weight of diethylene glycol, sodium polyoxyethylene alkyl ethercarboxylate 3 Parts by weight, sodium polyethylene glycol dicarboxylate 3
Parts by weight, 6 parts by weight of water-soluble acrylic resin, isopropano-
7 parts by weight of water, 55 parts by weight of distilled water,
A medium-strength propeller was stirred for 1 hour to sufficiently wet the carbon black powder with a liquid to prepare a coarse dispersion. Next, this dispersion liquid was subjected to a high-intensity forced dispersion treatment for 3 minutes using a homogenizer-dispersing machine to prepare a dispersion stock solution. A diluent obtained by mixing 120 parts by weight of distilled water and 10 parts by weight of glycerin was dropped into this dispersion liquid with stirring with a propeller to complete a colorant fine particle dispersion.

Next, as shown in FIG. 3, the image holding member provided with a work electrode to which an image signal can be input from the back side is put into a dispersion bath containing the above-mentioned dispersion liquid, and the back side goes out of the dispersion liquid bath. And a control electrode using a salt bridge was installed in the bath. This image holding member is made of a laminated structure of two organic photoconductor layers on which a transparent conductive layer of ITO is provided on a glass substrate having a thickness of 3 mm (the same as above), and the ITO conductive layer is used as a work electrode. The surface of the organic photoconductor layer was made smooth. Each electrode was connected to a potentiostat power supply. Then, while inputting an image to the optical image input section on the back side of the image holding member, a potentiostat power supply applies a 4.0 V D.V. between the work electrode and the counter electrode. C. Voltage was applied for 7 seconds.

Next, the image holding member after the completion of the image formation was taken out of the liquid, and it was confirmed that an image having an optical image density of 1.46 was formed on the surface of the image holding member.

Next, each of the dispersion of the present example and the dispersion of Example 1 was placed in a 300 ml polyethylene bottle, and
It was left for 3 months in an environment of 0 ° C. and 90 Rh%. Visual, filtration and shaking evaluations showed that the dispersion of Example 1 had the same liquid properties as before the standing test, but the dispersion of this example had a higher viscosity than the liquid before the standing test. And the presence of microsuspension in the liquid. Example 12 (Cleaning) In the same manner as in Example 2, a dispersion was prepared, taken out of the dispersion liquid bath through a printing process, and an image of dispersed color material fine particles was obtained on the image holding member. With plain paper. A conductive rubber roller and an insulating rubber roller are placed on the paper at a linear pressure of 400 g.
/ Cm between the plain paper and the image holding member and pressurized, +8
A bias voltage of 00 V was applied to the conductive rubber roller, and the sheet was rotated and transported. Then, the plain paper was peeled off from the image holding member immediately after the roller was carried out, and an image transferred with an optical image density of 1.43 was obtained on the plain paper. Next, a rubber shake is applied to the surface of the image holding member.
The transfer residual image forming material was removed by using a mold. As a result, the surface of the image holding member returns to the initial state, and the preparation for the next image formation is completed. Example 13 (Effect of pH change) Carbon black powder (average particle size: 0.1 μm) 10 parts by weight, diethylene glycol 15 parts by weight, sodium polyoxyethylene alkyl ethercarboxylate 3 parts by weight, polyethylene glycol Sodium dicarboxylate 3
Parts by weight, 6 parts by weight of water-soluble acrylic resin, isopropano-
7 parts by weight of water, 55 parts by weight of distilled water,
Medium-strength propeller stirring was performed for 1 hour to sufficiently wet the carbon black powder with a liquid to prepare a coarse dispersion.

Next, this dispersion liquid was subjected to a high-intensity forced dispersion treatment for 3 minutes using a homogenizer-dispersing machine to prepare a dispersion stock solution. 120 parts by weight of distilled water, 10 parts by weight of glycerin, fungicide (Proxel XL-2, ICI) 0.3
By weight, the diluted liquid mixture of parts by weight was dropped into this dispersion liquid while stirring with a propeller to complete a dispersion of coloring material fine particles for electrodeposition. The pH of this solution was adjusted with an aqueous hydrochloric acid solution and an aqueous sodium hydroxide solution to adjust the pH to 4.5, 6.0,
7.5 and 9.5 were set. The pH of this liquid at the starting point of coloring material fine particle precipitation is 5.0.

Next, as shown in FIG. 3, an image holding member provided with a work electrode to which an image signal can be input from the back side is placed in a dispersion bath containing the above-mentioned dispersion, and the back side is placed outside the dispersion bath. It was placed out of the way and a counter electrode, a control electrode using a salt bridge, was placed in the bath. This image holding member is made of a laminated structure of a two-layer organic photoconductor layer provided on a 4 mm-thick plate glass substrate provided with a transparent conductive layer of ITO. The ITO conductive layer is used as a work electrode, and an organic photoconductive layer is formed. The surface of the body layer was smooth. Each electrode was connected to a potentiostat power supply.

Then, while inputting an image to the optical image input section on the back of the image holding member, a potentiostat power supply is used to output a word.
Of 3.5 V between the negative electrode and the counter electrode. C. Voltage was applied for 9 seconds.

Next, the image-holding member on which the image formation was completed was taken out of the liquid, and the optical image density on the surface of the image-holding member was measured.
It was confirmed that images of 48 (dispersion of pH 6.0), 1.41 (dispersion of pH 7.5) and 1.15 (dispersion of pH 9.5) were formed. In the dispersion of pH 4.5, the dispersed particles settled at the bottom of the bath, and the dispersion state was unstable.

[0113]

As described above, according to the present invention,
High optical density, high resolution, low image thickness, high robustness image,
High safety, little waste, low energy consumption, and can be formed. In addition, the process and equipment are simple, and the method can be applied to the production of various kinds of prints in small quantities without using a printing plate.

Therefore, the present invention can realize various characteristics required particularly for an image forming technique used in an office.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a typical example of an image forming method of the present invention.

FIG. 2 is a diagram showing the relationship between the pH of a dispersion and dispersion stability.

FIG. 3 is a diagram schematically showing an example of an apparatus for implementing the present invention.

FIG. 4 is a diagram schematically showing an example of an apparatus for implementing the present invention.

FIG. 5 is a diagram schematically illustrating an example of an apparatus for implementing the present invention.

FIG. 6 is a diagram schematically showing an example of an apparatus for implementing the present invention.

FIG. 7 is a diagram schematically showing an example of an apparatus for continuously implementing the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Container 11 Image forming member 12 Cooperating electrode 13 Color material fine particles 14 Aqueous solvent 15 Dispersion liquid 16 Counter electrode 19 Imagewise exposure apparatus 20 Laser light source

Continuation of the front page (72) Inventor Ryujun Husband 430 Green, Nakai-cho, Nakai-cho, Ashigara-gun, Kanagawa Prefecture Inside Fuji Xerox Fuji Xerox Co., Ltd. (56) References JP-A-63-237085 (JP, A) JP, A) JP-A-7-268063 (JP, A) JP-A-50-139133 (JP, A) JP-A-7-133206 (JP, A) JP-A-4-104101 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) B41M 1/06

Claims (28)

(57) [Claims] Claims: 1. A colorant fine particle dispersion in which colorant fine particles having a dispersant adsorbed therein are dispersed in an aqueous liquid, wherein the pH value of the dispersion is a precipitation start pH when the dispersion is anodic deposition.
Set to a pH value between +1 and +3 compared to the point,
Also, when the dispersion is a cathodic deposition, it can function as one of the electrode pairs in the colorant fine particle dispersion set to a pH value between -3 and -1 compared to the pH value at which the deposition starts. An image holding member having a surface for holding an image, and a counter electrode as the other of the pair of electrodes, a step of preparing an immersed device; and a desired portion of the image holding member and the other of the pair of electrodes. By applying a voltage of less than 10 V to a certain counter electrode, a desired portion of the image holding member and the counter electrode are energized through the dispersion to change the pH value of the color material fine particle dispersion. Forming the image by changing the dispersion stability of the coloring material fine particles and electrochemically depositing and attaching the coloring material fine particles to a desired portion thereof. 2. The image forming method according to claim 1, wherein the image holding member is capable of flowing a current corresponding to an image pattern or forming an electric field. 3. An energization is performed such that the desired portion of the image holding member has a polarity opposite to the polarity of the ionized coloring material fine particles.
The image forming method according to claim 1, wherein: 4. The aqueous liquid according to claim 1, wherein a dispersant having an electrical property for binding, adhering or associating with the surface of the coloring material fine particles and stabilizing the dispersion of the coloring material fine particles is added to the aqueous liquid. Image forming method. 5. When the image forming portion of the image holding member is more anodic than the counter electrode, at least one kind of substance having a structure having an anionic group that dissociates in an aqueous liquid is used as the dispersant. The image according to claim 4 , wherein when the image forming portion of the image holding member is more cathodic than the counter electrode, one or more substances having a structure having a cationic group by ion dissociation in an aqueous liquid are used as the dispersant. Forming method. 6. The substance having a structure having an anionic group,
The image forming method according to claim 5, which is a substance having a carboxyl group. 7. A colorant particle dispersion electrolytic polymerization monomers while - the further contain, during image formation, precipitation and deposited allowed Ru claim 1, wherein as part of the electrolytic polymerization was while the image on the surface of the image holding member Image forming method. 8. An ionic water-soluble polymer material is further contained in the colorant fine particle dispersion, and the ionic water-soluble polymer material is deposited on the surface of the image holding member as part of an image during image formation. 2. The image forming method according to claim 1, wherein the image is adhered. 9. The method according to claim 1, wherein emulsion particles are further contained in the colorant fine particle dispersion, and the emulsion particle material is also deposited as a part of an image on the surface of the image holding member during image formation. Image forming method. 10. The color material fine particles having an average particle size of 0.1.
2. The image forming method according to claim 1, wherein the thickness is in a range of from 01 μm to 1.0 μm. 11. The image forming method according to claim 1, wherein a wetting agent having a boiling point of 120 ° C. or higher and a vapor pressure in the air of 100 mmHg or lower is added to the aqueous liquid. 12. A photoconductive substance capable of converting a light input as an image signal into a current signal is held on the image holding member, and the conductivity of the surface of the image holding member is increased in accordance with the image signal.
The image forming method according to claim 1, wherein an image is formed. 13. The image holding member according to claim 1, wherein an auxiliary electrode as an electrode connected to a power supply is in contact with or provided on the image non-holding surface side of the image holding member, and the image holding member functions as an electrode via the auxiliary electrode. Image forming method. 14. The image forming method according to claim 13, wherein the auxiliary electrode is a needle-shaped or pen-shaped electrode, and an image is formed on the surface of the image holding member in accordance with an image signal from the electrode. 15. The volume specific resistance of the colorant fine particle dispersion is 1
0 ⁵ Ω · cm or less image forming method according to claim 1, wherein the. 16. The image forming method according to claim 1, wherein the colorant fine particle dispersion is flowed or stirred during image formation. 17. The image forming method according to claim 1, wherein an agent having an antiseptic and antifungal effect is contained in the colorant fine particle dispersion. 18. The image forming method according to claim 1, wherein the temperature of the colorant fine particle dispersion is controlled during image formation. 19. The image forming method according to claim 1, further comprising the step of removing unnecessary image forming material deposited and adhered on the surface of the image holding member. 20. The image forming method according to claim 1, wherein the solid content of the dispersion is between 1% by weight and 40% by weight. 21. The image forming method according to claim 1, wherein the amount of the coloring material component in the solid component of the dispersion is between 30% by weight and 80% by weight. 22. A colorant fine particle dispersion in which colorant fine particles having a dispersant adsorbed therein are dispersed in an aqueous liquid, and when the pH value of the dispersion is anodic deposition, the starting pH of the dispersion is p.
It is set to a pH value between +1 and +3 as compared to the H point, and when the dispersion is cathodic deposition, a pH value between -3 and -1 as compared to the pH point at which precipitation begins. Contacting at least the holding surface of a holding member operable as one of the electrode pairs and having a holding surface for holding the colorant deposition film, with the colorant fine particle dispersion set to By applying a voltage of less than 10 V between the desired portion of the holding member and the counter electrode which is the other of the electrode pair, the desired portion of the holding member and the counter electrode are energized via the dispersion, and By changing the pH value of the fine particle dispersion, changing the dispersion stability of the coloring material fine particles, a desired portion of the holding member,
A method for forming a color material deposition film, comprising a step of depositing and adhering color material fine particles. 23. The method according to claim 22 , wherein the energization is performed while suppressing a foaming phenomenon in the holding member functioning as one of the electrode pairs. 24. A dispersion of coloring material fine particles in which coloring material fine particles having a dispersant adsorbed therein are dispersed in an aqueous liquid, and the pH value of the dispersion is set to p when the dispersion is anodic deposition.
It is set to a pH value between +1 and +3 as compared to the H point, and when the dispersion is cathodic deposition, a pH value between -3 and -1 as compared to the pH point at which precipitation begins. Contacting at least the holding surface of a holding member operable as one of the electrode pairs and having a holding surface for holding the colorant deposition film, with the colorant fine particle dispersion set to The desired part and the opposite electrode of the other electrode pair are energized through the dispersion to change the pH value of the colorant fine particle dispersion, thereby changing the dispersion stability of the colorant fine particles. A method for forming a coloring material deposition film, comprising: depositing and attaching coloring material fine particles to a desired portion of the holding member, wherein the holding member has a substrate having a conductive surface and a photoconductive material film. The energization is performed by irradiating the photoconductive material film with light. Method of forming a color material deposition film, characterized in that. 25. The current, in addition to the light irradiation to the photoconductive material film, the colorant deposition film according to claim 24, characterized in that it is carried out by application of a bias voltage to the photoconductive material layer Forming method. 26. is the substrate transparent substrate, formation of colorant deposition film according to claim 24 or claim 25 wherein the light irradiation is characterized by being performed from the side opposite to the photoconductive material film Method. 27. The method for forming a color material deposition film according to claim 22, wherein the color material fine particle dispersion contains a pH adjuster. 28. A holding member having a transparent substrate, a conductive film and a photoconductive material film formed in this order, which is manufactured by the method for forming a color material deposition film according to any one of claims 24 to 27 . A colored material deposited film formed body having a colored material deposited film formed on a photoconductive material film.