JPH07125433A - Coloring material transfer image recording method using supply of current - Google Patents

Abstract

PURPOSE:To form an image of high quality by controlling the discharge of a polar solvent from a polymeric gel by the supply of a current. CONSTITUTION:A transfer medium 112 composed of a water-containing polymeric electrolyte gel layer 116 is arranged between a pair of electrodes 114, 122. A current is supplied across a pair of the electrodes 114, 122 on the basis of image data to selectively discharge water to the outer peripheral surface of the gel layer 116. Oily ink is supplied to the transfer medium 112 to which water is discharged from an ink roll 110 containing an oily ink liquid to be transferred to the part where no water is discharged of the gel layer 116. This ink liquid is transferred to recording paper P.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color material transfer image forming method by applying current, and more particularly, to an image forming method using a polymer gel which transfers a medium to the surface by applying current as a transfer medium.

[0002]

2. Description of the Related Art Currently, the main qualities required for an image formed by an image forming (recording) apparatus are resolution, image density, image sharpness, gradation expression, color purity, and color superimposition. Can be mentioned.

The performance of the image recording apparatus is high recording speed, quiet sound, low running cost, small size and light weight, and both plain paper and recycled paper are used. There is a demand for things that can be done and maintenance-free. Recently, the basic characteristics of a recording device, such as resolution, image density, and recording speed, have risen to a certain level. Therefore, color expression is possible, regardless of the type of recording paper, compact and lightweight. Is especially emphasized.

Various image recording methods have been proposed so far, from industrial lithographic printing and stencil printing to office electrophotographic printers and thermal transfer printers, but plain paper that generally satisfies the above requirements. A color image recording system for use has not yet been realized.

[0005]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a color material transfer type image recording method capable of easily achieving high quality color image recording by a simple method.

[0006]

In order to solve the above-mentioned problems, the present invention provides (1) a polymer which releases a polar solvent to its surface by applying electric current and loses the wettability of the surface by releasing the electric current. The gel constitutes a transfer medium, and (2) the polymer gel is energized between a pair of electrodes to release the polar solvent in the energized portion, and (3) the transfer medium from which the polar solvent has been released is treated with the polar solvent. The non-affinity ink liquid is supplied to transfer the ink liquid to the non-conducting portion of the transfer medium.

That is, according to the present invention, there is provided a transfer medium comprising a polymer gel layer containing a liquid first medium containing a polar solvent and releasing the first liquid medium to the surface thereof by energization. The first liquid medium is disposed between the pair of electrodes, and an electric signal based on image data is passed between the pair of electrodes to cause the first liquid medium to be discharged to the surface of the polymer gel layer in the current-carrying region so that the first liquid medium is not connected to the current-carrying region. A latent image is formed on the transfer medium by the current-carrying region, and a liquid second medium containing a coloring material and having a non-affinity for the first medium is formed on the transfer medium on which the latent image is formed. By supplying the second medium, the second medium is moved to the non-conducting region of the transfer medium to form a visible image of the second medium thus transferred on the transfer medium, and a transfer target material is formed on the transfer medium. The visible image is transferred onto the material to be transferred by bringing them into contact with each other. Characterized by recording an image, the color material transfer image recording method according to energization is provided with.

The present invention will be described in more detail below. In the present invention, the first medium refers to a polar solvent or a solution in which a solute such as an electrolyte is dissolved in a polar solvent. Also, the second
The medium (1) contains a coloring material and is incompatible with the first medium in the sense that it is immiscible with the first medium.
Hereinafter, this second medium is referred to as an ink liquid.

The polymer gel used in the present invention is one in which the first medium contained therein is discharged to the surface by applying an electric current, and the wettability of the surface disappears when the electric current is released. Here, release of energization means non-energization or separation from the energization part. The polymer gel of the present invention comprises a polymer electrolyte gel obtained by crosslinking a cationic or anionic polymer (polyelectrolyte) and a high-performance gel prepared by adding metal ions to a solution of the polymer electrolyte to adjust the pH. And molecular complex gels.

The cross-linked polyelectrolyte gel is a gel composed of a network structure having a polymer chain as a skeleton and a solvent incorporated between the networks, and a polymer having an ionic dissociative group which is ionically dissociated by a polar solvent. It has a chain. Since the crosslinked polyelectrolyte gel is charged along the polymer chains, it is known that it has a strong affinity for polar solvents and can absorb and retain several hundred times its own weight of water, for example. A polyelectrolyte gel containing water is called a hydrogel.

The crosslinked polyelectrolyte gel has rubber viscoelasticity, and polar solvents such as water retained in the gel do not flow out even when an external force is applied to the gel. Further, when a gel is energized by an electrode device capable of applying a DC voltage, it has a characteristic that a polar solvent such as water is released from one electrode and the gel itself contracts at the other electrode. This phenomenon occurs because the polymer chains are charged. The shrunken gel can reabsorb polar solvents such as water. The crosslinked polyelectrolyte gel shows this behavior not only in a polar solvent such as water but also in a solution prepared by dissolving a solute such as a low molecular electrolyte in a polar solvent. Water is preferable as the polar solvent, but other polar solvents can be used as long as they are polar solvents capable of dissociating the ion-dissociable groups of the polymer electrolyte.

In the first aspect of the present invention, the first medium is normally held (when the energization is released) and is not discharged to the surface (the surface wettability disappears), and the first medium is energized by the energization. The transfer medium is constituted by the cross-linked polyelectrolyte gel having such characteristics that is released to the surface thereof. When the polymer electrolyte is a polyanion at the time of energization, the first medium is released at the cathode and the gel contracts at the anode. On the other hand, when the polyelectrolyte is a polycation, the first medium is released at the anode and the gel contracts at the cathode. When the first medium is a conductive solution in which an electrolyte such as sodium chloride, sodium hydroxide or potassium hydroxide is dissolved in a polar solvent, the gel and one electrode do not have to be in direct contact with each other. This is because electricity is achieved through the electrically conductive first medium containing the electrolyte. As the cross-linked polyelectrolyte, polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, poly-4-vinylpyridine, agar, alginic acid, collagen, gelatin, gum arabic, poly, which are cross-linked with a cross-linking agent such as methylenebisacrylamide. (Acrylamidomethylpropane sulfonic acid) or the like can be used.

An example of producing a crosslinked polymer complex gel will be described below. Preparation Example 1 Ion exchange containing 4M of acrylamidomethylpropanesulfonic acid, which is a monomer of the polymer electrolyte, 0.2M of methylenebisacrylamide as a cross-linking agent, and 0.04M of azobisisobutyronitrile as a polymerization initiator. Reaction with water at about 60-70 ° C for about 5 hours to give the desired poly (acrylamidomethylpropane sulfonic acid)
A (PAMPS) gel was obtained. This gel was washed and swollen in ion-exchanged water to obtain the desired PAMPS hydrogel. Preparation Example 2 After obtaining a poly (acrylamidomethylpropane sulfonic acid) gel in the same manner as Preparation Example 1, this was immersed in ion-exchanged water containing sodium hydroxide at a concentration of 0.05 M as an electrolyte. Thus, a desired PAMPS hydrogel incorporating an aqueous solution of an electrolyte was obtained.

On the other hand, the polymer complex gel is formed by adding metal ions to a high concentration aqueous solution of a polymer electrolyte and adjusting the hydrogen ion concentration (pH) of the aqueous solution. For example, a system in which calcium ions are added to an aqueous solution of polyacrylic acid exhibits the behavior shown in Table 1 below.

[0015]

[Table 1]

That is, this system reversibly forms or dissociates a complex due to a change in ambient pH. In the high pH region where the pH is 4 or more, the hydrogen ion concentration in the system is low, and therefore the carboxyl group of the polymer chain is dissociated into COO ⁻ and H ⁺ . At this time, electrostatic interaction between the side chain of the polymer and Ca2 + occurs to form a polymer complex. Due to the formation of this complex, the polymer solution system shows a large increase in viscosity. In particular, when the polymer concentration is sufficiently high, the entire solution system gels. On the other hand, in the low pH region of pH 3 or less, the hydrogen ion concentration in the system is high, so that the side chain of the polymer does not dissociate and C
Takes the form of OOH. Therefore, electrostatic interaction with Ca ²⁺ does not occur, and the polymer complex is not formed. When the polymer concentration is high enough, the system changes from the gel to a sol. In the present invention, the pH is lowered by the hydrolysis of water by applying electricity. According to the second aspect of the present invention, in a normal case (non-energization or release of energization), the first medium is held in a gel state and is not discharged to the surface (surface wettability disappears), and current is applied. Thus, the transfer medium is constituted by the polymer complex gel having such characteristics that the surface becomes a sol and the first medium is released to the surface. The polymer complex gel is
Not only the above polyacrylic acid, but also polymethacrylic acid,
It is formed between alginic acid and metal ions such as magnesium, calcium, strontium, and barium, and any suitable polymer complex gel can be used in the present invention.

An example of the polymer complex gel will be described below. Preparation Example 3 A 3 M aqueous solution of polyacrylic acid (pH = 2.7), which is a polyelectrolyte, was added with calcium chloride in an equimolar amount to the carboxyl groups of polyacrylic acid.
A highly viscous solution (sol) was transferred to an elastic gel to obtain a desired polymer complex gel.

As described above, when an electric signal based on image data is passed between the pair of electrodes, the first liquid medium is discharged to the surface of the polymer gel layer in the current-carrying region. A latent image is formed on the transfer medium by the energized area and the non-energized area from which the first liquid medium is discharged.

Next, the ink liquid is supplied to the transfer medium on which the latent image is formed. Usually, the ink liquid can be supplied by a porous roll containing the ink liquid.
When the ink liquid is supplied to the transfer medium, the ink liquid is not transferred to the energized region where the first liquid medium is discharged due to the non-affinity of the first liquid medium, and the ink liquid is not in the non-energized region (ink liquid Is selectively released only to the polymer gel layer portion where it is not released. The transferred ink liquid is a visible image.

Then, the material to be transferred (recording paper) is brought into contact with the transfer medium on which the developed image is formed, and the developed image is transferred to the recording paper to record the image. In the present invention, it is desirable to provide a means for continuously supplying the first medium on the inner peripheral surface of the polymer gel layer. By absorbing the first medium from the medium supplying means on the inner peripheral surface of the polymer gel contracted by the electrode reaction, the polymer gel in the contracted portion can be re-swelled. In this way, it is possible to continuously supply the first medium to the polymer gel layer.

Such a medium supply means supports, for example, a transfer medium on a cylindrical porous support, and a medium tank is formed by accommodating the first medium inside the cylindrical porous support. It is composed. At that time, when (1) the first medium is composed only of a polar solvent, the porous support also acts as an electrode (direct contact between the polymer gel layer and the electrode), or (2) the first medium is When it contains an electrolyte and becomes conductive, an electrode can be provided separately from the cylindrical porous support in a non-contact state with the polymer gel layer.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. The same parts are designated by the same reference numerals throughout the drawings. FIG. 1 shows the basic structure of an image recording apparatus according to the first embodiment of the present invention. The apparatus 100 includes a drum-shaped ink liquid transfer medium 112. Transfer medium 112
Are supported by a rotatable cylindrical porous support 114. This support 114 also serves as a common anode electrode and is applied with a positive potential. Therefore, the support 1
14 can be formed of a conductive material such as carbon. The transfer medium 112 is formed by covering the entire outer peripheral surface of the support 114 and forming the swollen cross-linked polymer electrolyte gel layer 116 containing the first medium as described in detail above. In this example, a polyanion hydrogel is used as the polymer electrolyte gel, and for example, the PAMPS hydrogel prepared in Preparation Example 1 can be used.

Inside the cylindrical porous support 114, water 120, which is the same first medium as that contained in the polymer electrolyte gel, is accommodated to form a water tank 118.
A cathode electrode 122 to which a signal potential (negative potential) is applied is provided in contact with the outer periphery of the polymer gel layer 116. The cathode electrode 122 can be composed of, for example, a multi-stylus electrode. Needless to say, both end surfaces of the drum-shaped transfer medium 112 are liquid-tightly closed by a lid or the like not shown.

Now, the image recording apparatus 100 has a porous ink roll 110 which rotates externally on a drum-shaped transfer medium 112.
Is equipped with. The ink roll 110 contains an ink liquid (oil-based ink liquid) that has no affinity for water, which is the first medium contained in the polymer gel 116.

Below the transfer medium 112, there is provided a transfer means 124 for bringing the material to be transferred (recording paper) P into sliding contact with the polymer gel layer 116 of the transfer medium 112. The transfer means 124 can be composed of, for example, a rubber roll.

In the image forming apparatus 100 having such a structure, as shown in FIG. 2, the transfer medium 112 and the ink roll 110 are rotated, the anode electrode 114 is set to a positive potential, and the cathode electrode 122 corresponds to the image data. When a signal potential (negative potential) S to be applied is applied, the PAMPS hydrogel 116, as already described in detail above, receives the cathode electrode 1
On the side of 22, the contained water is sequentially discharged as a water film W corresponding to the image information. No water is released into the areas of the PAMPS hydrogel 116 that are not energized. The energized area and the non-energized area form a latent image.

On the other hand, on the common anode electrode 114 side, P
The AMPS hydrogel 116 contracts. Next, the transfer medium 112 comes into contact with the ink roll 110 by rotation.
The area where the water film W is formed and the area where the water film is not formed on the transfer medium have different repellency / wettability with the oil-based ink liquid, and the oil-based ink liquid has a non-affinity with water. The oil-based ink liquid I migrates only to the formation area to form a visible image.

When the recording paper P is brought into close contact with the surface of the transfer medium 112 by the transfer means 124, the ink liquid I on the surface of the polymer gel layer 116 is transferred onto the recording paper P to record an image. The water W remaining on the transfer medium 112 is reabsorbed by the gel layer 116 and the gel surface is cleaned.

Further, the polymer gel contracted on the side of the anode electrode 114 absorbs the water 120 in the water tank 118 through the porous anode electrode 114 and returns to the initial state. By repeating the above process, continuous image formation can be achieved. Further, as described above, the water is continuously supplied to the gel layer by the water 120 in the water tank 118.
Water is supplied to the water tank 118 when the transfer medium 11 is used.
It can be performed from the two end faces.

FIG. 3 shows the basic structure of an image recording apparatus according to the second embodiment of the present invention. This image forming apparatus 200
Is an aqueous solution containing an electrolyte, except that the anode electrode is not in direct contact with the polymer gel layer,
It has the same configuration as the device 100 of the first embodiment.

That is, the transfer medium 212 of the apparatus 200
Has a rotatable cylindrical porous support 214,
No potential is applied here. Therefore, the porous support 21
The material 4 is only required to allow the ink liquid to pass therethrough, and can be formed of not only a conductive material but also other materials such as woven cloth.

The polymer electrolyte gel layers 216a and 216b, which cover the entire inner and outer peripheral surfaces of the porous support 214 and are swollen by containing the conductive aqueous solution as described in detail above, are each about 1 mm, for example. Is formed to a thickness of. In this example, as in the first example, a polyanion hydrogel is used as the polymer electrolyte gel, and the water contained in this contains an electrolyte.
Examples of such a polyelectrolyte hydrogel include:
PAMPS containing the aqueous electrolyte solution prepared in Preparation Example 2
Hydrogels can be used.

The inside of the cylindrical porous support 214 contains an aqueous electrolyte solution 220 to form an aqueous solution tank 218. Needless to say, the end surface of the roll-shaped transfer medium 212 is liquid-tightly closed by a lid or the like not shown.

A common anode electrode 226, which is set to a positive potential, is inserted through the central axis of the ink liquid transfer medium 212. The common anode electrode 226 is not in contact with the polymer gel layer 216a, and the common electrolyte electrode 220
I am only in contact with. Energization with the cathode electrode 122 is achieved through the electrolyte aqueous solution 220.

The operation of the image forming apparatus 200 described above is as follows.
The device is the same as the device of the first embodiment except that the common anode electrode 226 is set to a positive potential instead of the porous support 214, and the replenishment of the electrolyte solution is also the same. In addition,
In this embodiment, since the conductive aqueous solution containing the electrolyte is used as the first medium, the contraction of the polymer gel layer allows the first medium to be absorbed (re-swelled) more quickly, resulting in a more stable quality. Image formation is possible.

FIG. 4 shows the basic structure of an image recording apparatus according to the third embodiment of the present invention. This device 300 is the same as the device of the second embodiment shown in FIG. 3 except that the cathode electrode structure is different.

That is, the image forming apparatus 300 of this embodiment.
The cathode electrode structure 322 has a rotatable cylindrical transparent support 323. The transparent support 323 can be formed of a transparent electrode, for example.

A photoconductive layer 325 is formed so as to cover the entire outer peripheral surface of the transparent support 323. This photoconductive layer 325
Is substantially insulative when not irradiated with light and becomes conductive when irradiated with light. It is a well-known inorganic material such as CdS, ZnO, and amorphous silicon, or polyvinylcarbazole. It can be formed of an organic material such as. The photoconductive layer 325 circumscribes the outer polymer gel layer 216b of the transfer medium 212 that rotates at the same time.

Inside the cylindrical transparent support 323, at the contact with the gel layer 216b of the photoconductive layer 325, the photoconductive layer 325 is selectively irradiated with light through the transparent support 323 in accordance with image information. The optical head 327 causes the transfer medium 2
It is inserted and fixed over the entire length of 12. Optical head 3
27, a light emitting diode head, a laser head,
Any suitable head such as a plasma image bar, an electron beam excitation phosphor head, a liquid crystal shutter head, and a PLZT head can be used.

When an optical signal corresponding to image information is input, the optical head 327 selectively irradiates the photoconductive layer 325 with the light hν in response thereto. The light-irradiated portion of the photoconductive layer 325 becomes conductive and achieves conduction with the common anode electrode 226. Thus, the image formation as described in the second embodiment can be performed.

The third embodiment has an additional advantage that finer dots can be formed because the energizing portion is controlled by light. Needless to say, the cathode electrode structure 322 of this embodiment can achieve the same function even if it is used in place of the cathode electrode 122 of the first embodiment shown in FIG.

FIG. 5 shows the basic structure of an image recording apparatus according to the fourth embodiment of the present invention. This apparatus 400 has the same configuration as the image recording apparatus shown in FIG. 1 except that the transfer medium is formed of a polymer complex gel according to the second aspect of the present invention.

That is, in this image recording apparatus 400, the transfer medium 412 is entirely formed of the roll-shaped polymer complex gel 416. This polymer complex gel contains and retains water. For example, this polymer complex gel can be prepared, for example, from the polyacrylic acid-calcium complex gel shown in Preparation Example 3. Polymer complex gel roll 4
A common anode electrode 426 is formed through the central axis of the No. 16.

When electricity is applied between the pair of electrodes 122 and 426 based on the image data, the water in the polymer complex gel 416 forming the roll-shaped transfer medium 412 is electrolyzed and the pH is lowered in the vicinity of the cathode electrode 122. Anode electrode 42
The pH rises near 6. As detailed above,
In this case, the polymer complex remains a gel in the vicinity of the anode electrode 426, but a sol phenomenon occurs in the vicinity of the cathode electrode 122, that is, the surface of the transfer medium 412, and water is released. After that, as described with reference to FIG. 1, the oil-based ink is selectively transferred from the ink roll 110 and transferred onto the recording paper P.

[0045]

As described above, according to the present invention, a polymer gel is used as a transfer medium, and the first medium contained therein is discharged by energization, and the ink is transferred to the transfer medium from which the first medium is discharged. This is a method in which the liquid is selectively transferred to form a visible image, and this is transferred to a recording paper, and a higher quality image can be formed by a recording method similar to so-called lithographic printing.

Further, an image forming apparatus having a simple structure, light weight and inexpensive can be realized, and energy required for image formation can be reduced. Furthermore, a color image can be easily formed by exchanging the transfer medium, and since the ink used is a liquid, an image can be formed regardless of the type of recording paper as the material to be transferred. In addition, since the ink liquid is consumed only in the image forming portion, the running cost is low.

Furthermore, since the image forming apparatus to which the present invention is applied can be downsized with a simple structure, a multi-color image forming apparatus can be easily realized by incorporating a plurality of such image forming apparatuses.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic structure of an image recording apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an image recording method according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a basic structure of an image recording apparatus according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a basic structure of an image recording apparatus according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a basic structure of an image recording apparatus according to a fourth embodiment of the present invention.

[Explanation of symbols]

110 ... Ink roll, 112, 212, 412 ... Transfer medium, 114, 214 ... Porous support, 116, 216
a, 216b, 416 ... Polymer gel layer, 118, 218
... medium tank, 120, 220 ... first medium, 122 ...
Signal electrodes, 226, 426 ... Common electrode, 325 ... Photoconductive layer, 327 ... Optical head.

Claims (1)

[Claims] 1. A transfer medium, which contains a liquid first medium containing a polar solvent and is composed of a polymer gel layer which releases the first liquid medium on its surface upon energization, is arranged between a pair of electrodes. Then, the first liquid medium is discharged to the surface of the polymer gel layer in the current-carrying region by passing an electric signal based on image data between the pair of electrodes. An image is formed on the transfer medium, and a liquid second medium containing a coloring material and having a non-affinity for the first medium is supplied to the transfer medium on which the latent image is formed. The second medium is transferred to the non-conducting region of the transfer medium to form a visible image of the transferred second medium on the transfer medium, and the transfer medium is brought into contact with the transfer medium to form the visible image. Transferring an image onto the transfer material to record the image A method for recording an image of a color material transfer by energization, which comprises: