JPH03295680A - Image forming device - Google Patents

Abstract

PURPOSE:To ensure that an easily operable image forming device suited for printing a large amount of data at high printing quality by stirring ink using a stirring device to homogenize the quality. CONSTITUTION:Ink 2 as a recording material is formed in a uniform thickness by a coating roll 9 which rotates in 'E' direction on the surface (cylindrical) of an ink bearing roll 1. To homogenize the ink 2, a stirring roll 10 as a device for stirring the ink 2 is provided near an ink reservior 11 and is rotated in 'P' direction. In addition, the stirring effect of the ink 2 is improved by roughing the surface of the stirring roll 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a recording material whose adhesion changes when energized,
The present invention relates to an image forming apparatus such as a printing press or a printer that forms an image by selectively bringing the recording material into a non-contact state and a contact state with respect to an electrode portion.

[Prior Art] Conventionally used printing techniques include lithographic printing, letterpress printing, and gravure printing, but each of these methods requires complicated steps to produce plates. In addition, the ink patterning required dampening water, making it extremely troublesome to handle. Furthermore, the adhesion of the ink was easily affected by temperature and humidity, and it lacked environmental stability.

For this reason, there are many difficulties in applying these printing techniques to recording peripheral devices such as computers.

To solve the problems with these printers, for example,
One-type printers that use ink whose adhesion changes depending on the voltage application state are disclosed in Japanese Patent Application Laid-open No. 3-71359, Japanese Patent Application Laid-Open No. 63-71360, and Japanese Patent Application Laid-Open No. 63-71386. Are known.

[Problems to be Solved by the Invention] Among the conventional image forming apparatuses described above, those using lithographic printing, letterpress printing, gravure printing, etc., have the following problems: (1) Complicated plate production. It has the disadvantages of requiring a process, (2) cumbersome handling, and (3) poor environmental stability.

In the case of image recording using ink whose adhesion changes depending on the polarity of the applied voltage, since the ink is energized, the ink near the voltage application means
Electrolysis of water occurs and the pH value changes rapidly.

For this reason, the viscoelasticity differs locally, resulting in unevenness on the printed surface. As a result, there is a drawback that the image lacks stability when printing in large quantities. This is because the ink to which a voltage is applied is near the positive electrode.
Generates oxygen gas and becomes acidic, increasing ink viscosity.
Conversely, the ink near the negative electrode generates hydrogen gas and becomes basic, reducing the viscosity of the ink.

As mentioned above, as the viscosity of the ink progresses and the water on the ink surface is consumed by electrolysis, the electrical resistance increases, making it difficult to control the adhesion of the ink even when voltage is applied. Therefore, the stability of image recording cannot be ensured.

The present invention has been made in view of the drawbacks of the above-mentioned conventional techniques, and it is an object of the present invention to realize an image forming apparatus that is easy to handle and suitable for high-quality printing in large quantities.

[: Means for Solving Problem 1] The image forming apparatus of the present invention includes an original plate in which a pattern is formed by a conductive part and a non-conductive part to which a voltage is applied, and a state in which the voltage is applied to the original plate. In an image forming apparatus having a coating means for applying ink whose adhesion changes depending on the color of the image, the coating means is provided with an ink agitation means for making the ink material uniform.

[For production]

Since the ink is stirred by the stirring means and its material properties (pH value, viscoelasticity, etc.) are made uniform, unevenness does not occur on the printed surface.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a side view schematically showing the configuration of an embodiment of the present invention.

In the image forming apparatus shown in FIG. 1, an ink carrying roll 1 is a member that has a cylindrical shape and rotates in the direction of arrow A.

The ink carrying roll 1 is preferably made of a conductive material such as aluminum, copper, or stainless steel. Ink 2, which is a recording material, is applied onto the surface (cylindrical surface) of the ink carrying roll 1 by a coating roll 9 rotating in the direction of arrow E.
is formed to a uniform thickness. The material constituting the ink carrying surface of the ink carrying roll 1 is a material that can form a desired layer of ink 2 on the surface (by conveying the ink 2 by rotation in the six directions of the arrows). If so, it can be used without any particular restriction. More specifically, a conductor made of metal such as stainless steel is preferred.

The surface of the ink carrying roll 1 made of such a material is
The surface may be smooth, but from the point of view of further improving the conveying and supporting properties of the ink 2, the surface may be appropriately roughened (for example, according to JIS BO
It is preferable that the surface roughness of 601 be approximately IS. The ink 2 is replenished into the ink reservoir 11.

As is clear from the above description, in this embodiment, the application means is comprised of the ink carrying roll 1 and the coating roll 9, and the in-stirring means is comprised of the stirring roll 10.

The printing plate 4 on the plate roll 3 rotating in the direction of arrow B comes into contact with the ink 2 on the surface of the ink carrying roll 1.
The ink of ink 2 is transferred to the image area to form an ink image. As the printing plate 4, any conventionally known printing plate can be used as long as the printing plate is composed of a conductive part and an insulating part. For example, a plate for offset printing, a plate for gravure printing, a letterpress, etc. can be used. Alternatively, a voltage may be applied between the printing plate 4 and the ink carrying roll 1 so that the ink does not adhere to the conductive parts of the plate, and the ink adheres only to the insulating parts. Further, a further roll may be interposed between the printing plate 4 and the ink carrying roll 1 to form a more uniform ink layer, or the rolls may be used as a pair of conductive members and a voltage may be applied to them. .

Next, the ink image on the printing plate 4 is transferred to the plan cylinder 5 rotating in the direction of the arrow C while being in pressure contact with the printing plate 4, and the ink image on the plan cylinder 5 is further transferred to the plan cylinder 5 while being in pressure contact with the plan cylinder 5. By transferring the ink image onto a recording medium 7 (paper, cloth, metal sheet, etc.) passing in the F direction between impression cylinders 6 rotating in the direction F, the ink image is transferred onto the recording medium 7, which is an image receiving body. A corresponding image is formed.

In some cases, the ink image on the plate 4 may be directly transferred onto the recording medium 7 without providing the plan cylinder 5, but the surface material of the plan cylinder 5 can prevent abrasion and deterioration of the printing plate 4. Furthermore, an image having the same pattern as the printing plate 4 can be obtained on the recording medium 7.

Now, if the ink layers on the plan cylinder 5, printing plate 4, and ink carrying roll 1 are not removed after printing is completed, the layer formed by the ink 2 will dry and cause problems in the next printing.

In addition, the physical properties (pH
5 viscoelasticity, electrical resistance, etc.) changes locally, and the recording material 7
In order to equalize the ink 2 in this embodiment, a stirring roll 10 serving as a stirring means for the ink 2 is provided near the ink reservoir 11 in order to equalize the ink 2 since the image formed thereon will be uneven.

As the stirring roll 10, a roll made of metal such as stainless steel, resin, etc. and having a diameter of 20 mm is used, and this roll is arranged with a gap of 0.8 to 1.2 mm from the ink carrying roll 1, and the arrow F peripheral speed approximately 30 t in the direction
It is configured to rotate at ag/sec.

In FIG. 1, the ink 2 that has not been transferred onto the printing plate 4 is stored in an ink reservoir 11, is stirred by the rotation of the stirring roll 10, becomes uniform, and is used again for image recording.

Although a stirring means that is not specially treated may be used, roughening the surface of the stirring roll 10 increases the effect of scraping the ink 2 and improves the effect of stirring the ink 2.

The method for roughening the surface may be any method such as mechanical processing such as knurling or cutting, chemical processing such as etching, or metal spraying methods such as sandblasting or plasma coating. It's not something you can do.

When roughening the surface of the stirring roll 10 as described above, the ten-point average surface roughness RZ (JIS 80601-1982
) is preferably 1 to 1000 μm, more preferably 1
It is desirable that the thickness be 0 to 500 μm.

In this example, recording was performed using a stirring roll 10 whose surface was formed by sandblasting to a surface roughness RZ of 10 μm, and another whose surface roughness was formed to a surface roughness R2 of 500 μm. Also showed excellent effects on ink agitation, a homogeneous ink layer was formed on the surface of the ink carrying roll 1, and recorded images without fogging, ghosting, image distortion, etc. could be obtained.

Further, it is preferable to use a stirring roll 10 having a spiral groove on its surface. In this way, when the stirring roll 10 rotates, the spiral groove advances in the longitudinal direction of the stirring roll 10, and the ink 2 is carried along with the progress of the Yuki spiral groove, thereby improving the stirring effect.

In providing the spiral grooves as described above, as shown in FIG.
b, 10c, 10d, and IOe may be combined. In this case, when the stirring roll 1o rotates in the direction of the arrow P in FIG. 2, the spiral grooves 10b to 10e move in the direction of the arrows Q and R in FIG. 2, respectively.

The ink 2 moves in the S and T directions, respectively, and the ink 2 is also carried in the Q, R, S, and T directions. The ink transported in the directions of the arrows Q and R and in the directions of the arrows S and T are mixed, so that the stirring effect is further improved.

Furthermore, when a plurality of spiral grooves are combined as described above, the spiral grooves at both longitudinal ends of the stirring roll 10 (grooves 10b and 10e in FIG. If the ink 2 is formed in a direction that advances inward, the agitated ink 2 will reach the stirring roll 10.
This is effective because it prevents the material from spreading outward from both ends in the longitudinal direction.

In addition, although a stirring spout/hole is used in the above embodiment, the stirring means is not limited to this, and instead of being composed of a roll-shaped member, it may be composed of a rotating member such as a one-rotation belt. Also good. Alternatively, for example, the ink may be peeled off from the ink roll by electricity, a blade, etc., stored in an ink container, and stirred using a general stirring means such as a stirring rod or a stirring blade.

In this embodiment, cleaning in the printing process is performed by using a blade made of an electrically conductive material that can be pressed onto and released from the printing plate 4, the printing cylinder 5, the ink carrying roll 1, and other rollers to which ink adheres. It can be implemented by

Next, other requirements for implementing the image forming apparatus of the present invention will be explained.

In FIG. 1, the printing plate 4 may have an insulating film on which an image-like conductive pattern is formed by discharge breakdown on a base material made of a conductive material. Furthermore, a plate having a photographic image in which a conductive pattern of a silver image is formed by depositing silver particles on a base material made of a conductive material can also be used. Further, the shape of the plate is not limited to a flat surface, and may be a roll shape, a curved shape, or a polygonal shape.

The shape of the ink application member is not limited to a roll, and a blade-like application member may also be used. The shape of the conductive member is not limited to a roll, and a plate-shaped conductive member may be used.

The printing plate 4 wound around the plate roll 3 is in contact with the ink 2 on the surface of the ink carrying roll 1 described above.
For example, as shown in FIG. 2, a desired pattern 4 made of an insulating material is formed on a base material 4a made of a conductive material such as metal.
b is provided.

As the material of the base material 4a, aluminum, copper, stainless steel, platinum, gold, chromium, nickel, steel copper, carbon, etc., or conductive polymers or various polymers in which metal fillers are dispersed are used. Materials for pattern 4b include thermal transfer recording materials (mainly wax and resin),
Electrophotographic toners, vinyl polymers, and natural or synthetic polymers are used.

In this way, the power supply 103 is connected between the printing plate 4 and the ink carrying roll 1.
By applying a voltage, the adhesion of the ink 2 in contact with the conductive portion of the printing plate 4 changes, and the difference in adhesion causes the ink 2 to adhere in a pattern on the printing plate 4, creating an ink image. form. Practically speaking, the voltage of the power supply 103 is preferably a DC voltage of 3 to 100V, more preferably 5 to 80V. Image quality can be further improved by applying an AC bias voltage (10V to 1oov) of high frequency (10) 1z to 100kHz). Can be sharpened.

In FIG. 1, the printing plate 4 side is the cathode and the ink carrying roll 1 side is the anode, but depending on the properties of the ink used, the plate 4 side may be the anode and the roll 1 side may be the cathode.

Specifically, the voltage from the power source 103 is preferably applied between the rotation axes of the printing roll 3 and the ink carrying roll 1, respectively.

The thickness of the layer of ink 2 formed on the surface of the ink carrying roll 1 is (the thickness of the ink carrying roll 1 and the coating roll 9
the size of the gap, the fluidity or viscosity of ink 2,
Although it varies depending on the material or roughness of the surface of the ink carrying roll 1 or the rotation speed of the roll 1, etc.), the ink transfer position where the roll 1 faces the pattern plate 4 on the plate roll 3 is approximately 0.001 to About 100 mm,
Furthermore, it is preferable that it is 0.001-10 mm.

If the layer thickness of the ink 2 is less than 0.001 mm, it becomes difficult to form a uniform ink layer on the ink carrying roll 1. On the other hand, if the ink layer thickness exceeds 100 mm, it becomes difficult to convey the ink 2 while keeping the surface layer of the ink layer (the layer in contact with the conductive pattern plate 4) at a uniform circumferential speed. 1 and conductive pattern plate 4
It is no longer easy to connect electricity to the device.

If the ink 2 contains water (water-soluble ink, emulsion ink), it can be used in the image forming method of the present invention by changing from adhesive to non-adhesive by applying a voltage.

The mechanism by which ink changes from adhesive to non-adhesive due to voltage application will be explained.

When the ink is energized by applying a voltage, the ink is electrolyzed and gas is generated, and this gas prevents the ink from adhering to the electrodes. In order for the ink to electrolyze and generate gas, the ink contains a solvent such as water, alcohol, or glycol, or a solvent in which an electrolyte such as sodium chloride or potassium chloride is dissolved. The electrical resistance of the ink is
The lower the resistance, the better, and it is preferable that the volume resistance is 10 5 Ω·CI or less. When the volume resistance exceeds 105Ω·CII+, the amount of current flowing decreases, or a high voltage is required to prevent the amount of current flowing. This ink moves almost entirely in the thickness direction (hereinafter referred to as bulk movement) in the portion of the ink layer to which a voltage is applied.

When the ink used in the present invention is a low-viscosity liquid such as water or alcohol, the cohesive force is weak and suitable adhesion cannot be obtained. The viscosity of the ink is a shear rate of 10 rad/3. 10' to 1010 poise at a temperature of 25°C, and even 1
04 to 108 poise is preferred. Furthermore, when the ink used in the present invention is applied to a platinum-plated stainless steel plate vertically erected to a thickness of 2 ma+, the ink is substantially removed in an environment of a temperature of 25°C and a humidity of 60%. It is preferable that the material be of such a level that it can be held on a platinum-plated stainless steel plate. In addition, when ink was sandwiched between the two platinum-plated stainless steel plates and the thickness of the ink was 2 mm, and the two platinum-plated stainless steel plates were separated from each other at a speed of 5 cm/sec with no voltage applied. In addition, it is preferable that the ink adhere to both plates to the same extent.

An ink that uses the above mechanism is composed of, for example, inorganic or organic fine particles and a liquid dispersion medium. The fine particles in the ink make it easier to cut the ink and improve the resolution of the image. The inks used in the present invention are amorphous and non-Newtonian in flowability.

When the change in ink adhesion is caused by Coulomb force, charged particles or easily charged particles are used as all or part of the particles, and are kneaded in a liquid dispersion medium described below, such as in a homogenizer, colloid mill, or ultrasonic disperser. Charged particles are thereby generated. Particles that are positively charged include metal (Au, Ag, Cu, etc.) particles, sulfides (sulfide ZnS, antimony sulfide Sb2S3, potassium sulfide 2S, calcium sulfide CaS, germanium sulfide GeS, cobalt sulfide CO5, tin sulfide SnS
, iron sulfide FeS, copper sulfide Cu2S, manganese sulfide Mn
S, molybdenum sulfide M0253, etc.) particles, silicic acid (
Orthosilicic acid H45i04, metasilicic acid H2SiO3,
Mesotrisilicate)12Si20. , mesotrisilicate) +4
51303, mesotetrasilicic acid H65i40+, etc.)
Particles, polyamide resin particles, polyamideimide resin particles, etc. can be used, and particles to which a negative charge is imparted include iron hydroxide particles, aluminum hydroxide particles, fluorinated mica particles, polyethylene particles, montmorillonite particles, Fluororesin or the like can be used. Furthermore, polymer particles containing various charge control agents used as toners for electrophotography can be used.

The above-mentioned fine particles have an average particle diameter of 100 μm or less,
Preferably 0.1μI11-20μm, especially 0.1μ
Fine particles with a diameter of 10 μm or more and 10 μm or less can be used.
It can be contained in an amount of at least 3 parts by weight, preferably 3 parts by weight to 90 parts by weight, and more preferably 5 parts by weight to 60 parts by weight.

In addition, the liquid dispersion medium used in the ink includes ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (weight average molecular weight, about 100
-1000), ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, methylcarpitol,
Ethyl carbitol, butyl carpitol, ethyl carpitol acetate, diethyl carpitol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, glycerin, triethanolamine,
Formamide, dimethylformamide, dimethylsulfoxide, N-methyl-2pyrrolidone, 1,3-dimethylimidazolidinone, N-methylacetamide, ethylene carbonate, acetamide, succinonitrile, dimethylsulfoxide, sulfolane, furfuryl alcohol, N
, N-dimethylformamide, 2-ethoxyethanol, hexamethylphosphoric triamide (hexamethylphosphoric triamide), 2-nitropropane, nitroethane, γ-butyrolactone, propylene carbonate, 1
, 2.6-hexandriol, dipropylene glycol, hexylene glycol and the like can be used alone or in combination of two or more of them. The liquid dispersion medium is ink 1
00 parts by weight, 40 to 95 parts by weight, and even 60 to 8 parts by weight.
It is preferable to contain 5 parts by weight.

In addition, in order to control the viscosity of the ink, 1 to 90 parts by weight, more preferably 1 to 50 parts by weight, particularly 1 to 20 parts by weight of the above-mentioned polymer soluble in the liquid dispersion medium is added to the ink based on 100 parts by weight of the ink material. It can be contained in a proportion of parts by weight. Such polymers include plant-based polymers such as guar gum, locust bean gum, gum arabic, taragant, carrageenan, pectin, mannan, and starch; microbial polymers such as xanthan gum, dextrin, succinoglucan, and curdlan; gelatin, casein, etc. Animal-based polymers such as , albumin, and collagen; cellulose-based polymers such as methylcellulose, ethylcellulose, and droxyethylcellulose, or starch-based polymers such as soluble starch, carboxymethyl starch, and methyl starch; alginic acid-based polymers such as propylene glycol alginate, and alginates. , other semi-synthetic polymers such as polysaccharide derivatives: vinyl polymers such as polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, carboxyvinyl polymer, sodium polyacrylate; other polyethylene glycol, ethylene oxide, propylene oxide block copolymers , alkyd resin, phenol resin, epoxy resin, aminoalkyd resin, polyester resin, polyurethane resin, acrylic resin, polyamide resin, polyamideimide resin, polyesterimide resin, silicone resin, and other synthetic polymers are used alone or in combination of two or more. be able to. It is also possible to use greases such as silicone grease and liquid polymers such as bolybdenum.

Since the change in ink adhesion is caused by the generation of gas due to electrolysis, the liquid dispersion medium should be water, alcohols such as methanol or ethanol, solvents with hydroxyl groups such as glycerin, ethylene glycol, propylene glycol, or A solvent in which an electrolyte such as sodium chloride or potassium chloride is dissolved is preferably used. The contents of the liquid dispersion medium and fine particles are the same as those described above. In particular, it is preferable to use water or a liquid containing water as the liquid dispersion medium because hydrogen gas is likely to be generated on the negative electrode side. When water and another liquid dispersion medium are mixed, the content of water is preferably 1 part by weight or more, more preferably 5 parts by weight or more and 99 parts by weight or less, based on 100 parts by weight of the ink.

In a preferred embodiment of the ink, considering the viscoelastic properties of the ink, it is preferable to use swellable fine particles capable of retaining the liquid dispersion medium in the particles as all or part of the fine particles. Such swelling fine particles include, for example, Na-
Fluoride micas such as montmorillonite, Ca-montmorillonite, 3-octahedral synthetic smectite, Na-hectolite, Li-hectolite, Na-teniolite, Na-tetrasilicic mica and Li-teniolite, synthetic mica, silica, etc. .

The above-mentioned fluorinated mica can be represented by the following formula (1).

General formula (1) % formula %) In the formula, W is Na or Li, X and Y are Mg", Fe"N
6-coordinate ions such as i'', Mn'', AI'', Fe3◆, Li+, Z is ^13+, 5i4+, Ge4
◆ pe3+, 93+ or a combination of these (^13
+15i4+) represents a cation with a coordination number of 4.

The average particle diameter of the swellable fine particles is 0.1 to 20μ in dry state.
m, more preferably 0.8 to 15 μm, especially 0.8 to 8 μm. The content of the swellable fine particles may be the same as the content of the fine particles described above, but it is preferably 8 parts by weight to 60 parts by weight based on 100 parts by weight of the ink. It is also preferable to use swellable fine particles having charges on their surfaces.

The ink may contain colorants such as carbon black and other dyes and pigments that are generally used in the fields of printing and recording, if necessary. When the ink contains a coloring material, the content of the coloring material is 0.00 parts by weight per 100 parts by weight of the ink.
1 to 40 parts by weight, more preferably 1 to 20 parts by weight. Further, instead of or together with the coloring material, a coloring compound that develops color upon application of voltage may be contained.

In addition, electrolytes that give conductivity to ink, thickeners,
It may contain a thinning agent, a surfactant, etc. or,
It is also possible for the above-mentioned fine particles themselves to also function as a coloring material.

In order to obtain the ink described above, for example, a liquid dispersion medium and fine particles may be mixed by a conventional method.

[Effects of the Invention] Since the present invention is configured as described above, it has the following effects.

In the present invention, the adhesion of the ink changes depending on the polarity of the applied voltage, and this is used to form an image.
It has excellent environmental stability and is very easy to handle, and by incorporating an ink stirring means, the ink can be kept in a homogeneous state at all times, thereby ensuring stability in image formation.

That is, according to the invention, by applying a voltage. By stirring, it is possible to eliminate local deterioration of the r-ink and prevent fogging and image chipping.

Furthermore, as described above, the image forming apparatus is easy to handle and has excellent image stability.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing the configuration of an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a stirring roll 10 with spiral grooves on its surface, and FIG. 3 is a diagram showing the configuration of the stirring roll 10 used in the apparatus shown in FIG. 1. FIG. 2 is a schematic perspective view showing an example of a printing plate. 1... Ink carrying roll, 2-- Ink, 3--
・Plate roll, 4...Printing plate, 4a...
・Base material, 4 b-... pattern, 5...
Plan cylinder, 6--Impression cylinder, 7--Recorded object, 8--Ink image, 9--Coating roll, 10--Stirring roll, 10 b ~ 10
e-Spiral groove, 11-...Ink reservoir.

Claims (1)

[Claims] 1. An original plate in which a pattern is formed by a conductive part and a non-conductive part to which a voltage is applied, and an ink whose adhesion changes depending on the voltage application state is applied onto the original plate. What is claimed is: 1. An image forming apparatus having a coating means for uniformizing the material of the ink, wherein the coating means is provided with an ink stirring means for making the material of the ink uniform. 2. The image forming apparatus according to claim 1, wherein the ink carrying roll and the coating roll constitute the coating means, and the stirring roll constitutes the ink stirring means.