JPH0414452A - Picture forming device - Google Patents

Abstract

PURPOSE:To prevent the temperature of an ink from rising by the Joule heat produced upon current application by providing a coating means with an ink cooling means. CONSTITUTION:A coating means consists of an ink carrying roll 1 and a coating roll 9 and the two units of ink cooling means are provided consisting of water supply devices 11 and 13, pipes 12a, 12b and 14a, 14b and water passageways 1a and 3a, respectively. The ink carrying roll 1 is provided with a thermistor 15 to serve as a temperature sensor. The thermistor 15 is changed in resistance with a change in the temperature of cooling water and this resistance is converted into voltage E2 through an electric source E1 and a resistor R1 and this voltage is compared with a reference voltage E0 by a comparator C. An output produced by the comparator C as a result of its comparison activates a relay R to open and close through a relay driver RD, thereby controlling an electric source E3 to actuate a pump 15e between on and off conditions. In this way the supply of the cooling water is controlled and the temperature of an ink 2 is maintained at a predetermined value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a recording material whose adhesion changes when energized,
This technology relates to a technique for forming an image by selectively bringing the recording material into a non-contact state and a contact state with respect to an electrode part, and relates to various image forming apparatuses such as printing machines and printers, for example. be.

[Prior art] In printing technology, lithographic printing, letterpress printing, gravure printing, etc. are used, but these methods require complicated steps to prepare plates and require ink buttering. It was very difficult to handle, as it required dampening water. As a method to solve these problems, the present applicant electrically imparts partial (pattern-like) adhesiveness to the ink, and uses the difference between the adhesiveness and non-adhesion of this ink to perform recording. He was the first to propose a recording method for
-30279).

[Problems to be Solved by the Invention] Among the above-mentioned conventional image forming apparatuses, those using lithographic printing, letterpress printing, gravure printing, etc. have the following problems: (1) A complicated process is required to prepare a plate. , (2) cumbersome handling, and (3) poor environmental stability.

The method of electrically imparting partial tackiness to ink had a problem because the Joule heat generated by passing electricity through the ink evaporated the water in the ink. . Specifically, the electrical resistance of the ink increases, making it difficult to conduct electrical non-adhesion, resulting in deterioration of image quality, and the viscosity of the ink increasing, making it difficult to transfer the ink to the image receptor, resulting in poor image quality. The problem was that the concentration decreased.

This is because the temperature of the ink rises due to the Joule heat generated as the ink is energized, and the evaporation of water contained in the ink is accelerated. In this state, the electrical resistance of the ink increases, making it difficult for current to flow, making it difficult to prevent the ink from adhering, and as a result, fogging occurs in the recorded image.

The present invention has been made in view of the drawbacks of the prior art described above, and an object of the present invention is to realize an image forming apparatus that is easy to handle, has high print quality, and is suitable for large-volume printing.

[Means for Solving the Problems] An image forming apparatus of the present invention includes a coating means for coating an ink whose adhesion changes depending on the state of voltage application on an original, wherein the coating means includes: An ink cooling means is provided to cool the ink.

[Function] Since the ink cooling means is provided, it is possible to prevent the temperature of the ink from rising due to Joule heat generated by energization. In this case, the temperature of the ink can be detected using a temperature detection means such as a thermistor, and the temperature can be maintained at a constant temperature by an ink cooling means.

[Embodiments] Hereinafter, embodiments of the image forming apparatus of the present invention will be described with reference to the drawings.

FIG. 1 shows a side view showing essential parts of a first embodiment of an image forming apparatus of the present invention.

The ink carrying roll 1 is a member that has a cylindrical shape and rotates in the direction indicated by the arrow, and is made of a conductive material such as aluminum, copper, or stainless steel. The surface of the ink carrying roll 1 (
Ink 2, which is a recording material supplied to an ink reservoir 10 by a coating roll 9 rotating in the direction of arrow E, is formed on the cylindrical surface 2) to have a uniform thickness.

The ink carrying roll 1 is connected to one end of the DC power supply 103, and forms a cathode of a pair of electrodes formed by the facing plate roll 3.

Further, the ink carrying roll 1 and the printing roll 3 have a hollow structure, and are configured to allow cooling water to be circulated inside. Water is supplied to the ink carrier roll 1 from a water supply device fill to a water channel 1a inside the ink carrier roll 1 through a pipe 12a, and water is supplied to the printing roll 3 from a water supply device 1.
3 to the inner water channel 3 of the plate roll 3 by the vibrator 14a.
Water is supplied to a. As a result, the ink carrying roll 1
, the ink 2 and the plate roll 3 are cooled. The cooling water is supplied to the water supply system again via pipes 12b and 14b.
, 13, respectively. In this embodiment, the ink carrying roll 1 and the coating roll 9 constitute the coating means, and the water supply devices 11, 13, the vibrators 12a, 12b, 14a, f4b, and the water channels 1a, 3a serve as two types of ink. A cooling means is configured.

At that time, a method of detecting the temperature of the ink 2 and controlling the circulation of the cooling water will be explained.

The ink carrying roll 1 is provided with a thermistor 15 serving as a temperature detection sensor.

The drive structure of the ink cooling means is constructed as shown in FIG.

The resistance of the thermistor 15 changes depending on the temperature of the cooling water, and this resistance value is determined by the power source E and the resistor R.

is converted into a voltage E2 by a reference voltage E2 by a comparator C. compared to The output from the comparison result of the comparator C causes the relay R to open and close via the relay driver RD, and the pump 15e is turned on and off by the power source E3.
N, OFF control. This controls the supply of cooling water and keeps the ink 5 at a constant temperature. Water is also supplied to the plate roll 3 by the same structure as the ink carrying roll 1, and the plate 4 and the plate 4 wound on the upper surface of the plate roll 3 are supplied with water.
The ink 2 adhering to is cooled. Ink carrying roll 1
is made of a conductor such as aluminum, copper, or stainless steel.

The ink 2 on the surface of the ink carrying roll 10 is in contact with the plate 4, which is an original plate wound on the upper surface of the plate roll 3 as described above. The plate roll 3 is rotating in the direction of arrow B in the opposite direction to the roll 1. In version 4, for example, as shown in Figure 3,
A desired pattern 4b made of an insulating material is provided on a base material 4a made of a conductive material such as metal.

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

By turning on the switch 11 and applying a voltage from the power source 103 between the plate 4 formed as described above and the ink carrying roll 1, the adhesion of the ink 2 that comes into contact with the conductive portion of the plate 4 changes. Due to the difference in adhesion, the ink 2 is deposited on the plate 4 in a pattern, thereby forming an ink image. Practically speaking, the voltage of the power supply 103 is preferably a DC voltage of 3 to 10V, more preferably 5 to 80V, and a high frequency (10Hz
By further applying an AC bias voltage of ~100 kHz), the image quality can be made even sharper.

In FIG. 1, when electricity is repeatedly applied between the ink carrying roll 1 and the plate 4, the ink 2 generates heat due to the electricity application.
Moisture in the ink evaporates, increasing electrical resistance and deteriorating image quality. However, in this example,
By supplying cooling water by the water supply devices 11 and 13, the ink carrying roll 1 and the plate roll 3 are cooled, and drying of the ink 2 is prevented, so that it is possible to stably print a large amount. .

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

In this example, water is used as the cooling medium, but olefin, methyl chloride,
Organic refrigerants such as dichloromethane, refrigerants such as carbon dioxide gas and ammonia, and cooling devices using these may also be used.

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

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
(This varies depending on the size of the gap between It is preferable that it is about .001 to 1100a.

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 layer thickness of the ink 2 exceeds 100 mm, it becomes difficult to convey the ink 2 while maintaining a uniform circumferential speed on the surface layer of the ink layer (the layer on the side that contacts the conductive pattern plate roll 4). It is also difficult to conduct electricity between the ink carrying roll 1 and the plate 4.

Next, the ink image formed on the plate 4 is transferred to the blank cylinder 5 which rotates in the direction of the arrow C while being in pressure contact with the plate 4, and the ink image on the blank cylinder 5 is further transferred in the direction of the arrow C while being in pressure contact with the blank cylinder 5. A recording medium 7 (paper,
(cloth, metal sheet, etc.) to form an image 8 corresponding to the above ink image on the recording medium 7.

In some cases, the ink image on the plate 4 may be directly transferred onto the transfer medium 7 without providing the blank cylinder 5, but for example, a blank cylinder made of a material such as silicone rubber, fluorine rubber, nitrile rubber, or butyl rubber may be used. 5, it is possible to prevent the plate 4 from deteriorating due to abrasion, and it is also possible to obtain an image (positive image) with the same pattern as the plate on the recording medium.

As explained above, the image forming apparatus of the present invention supplies a specific ink 2 between an electrode (plate) having a desired insulating pattern and a counter electrode, and applies a voltage between the pair of electrodes. Accordingly, image formation is performed by utilizing the fact that the adhesion of ink 2 changes depending on the pattern of the electrodes.

Therefore, the device of the present invention uses a type of ink that has adhesive properties when no voltage is applied, and loses its adhesive properties when a voltage is applied.

The ink 2 used in these image forming methods will be described below.

Regarding the mechanism by which the ink 2 changes from adhesive to non-adhesive due to voltage application, the following case can be considered.

This is a case in which the ink 2 is electrolyzed and generates gas due to energization due to voltage application, and the adhesion properties change.

In this case, the ink is adjusted so that it inherently has adhesive properties, and when a voltage is applied, the ink 2 generates gas near one of the electrodes, and this gas prevents the ink 2 from adhering to the electrode. In order for the ink 2 to electrolyze and generate gas, the ink 2 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 lower the electrical resistance of the ink 2, the better, and the volume resistivity is preferably 10 5 Ω·cm or less. If the volume resistance exceeds 10 5 Ω·cn+, the amount of current flowing decreases, or a high voltage is required to prevent the amount of current flowing from decreasing.

Further, regarding the transfer of the ink 2 to the plate 4, almost the entire portion of the ink layer in the thickness direction is transferred (hereinafter referred to as bulk transfer) in the portion where the voltage is applied.

If the ink 2 is a liquid such as water or alcohol, its cohesive force is weak and suitable adhesiveness cannot be obtained. For this reason, ink can be applied, for example, to a platinum-plated stainless steel plate held vertically.
It is preferable that when the ink 2 is deposited to a thickness of 0.01111, the ink 2 is substantially retained on the platinum plated stainless steel plate. In addition, when the ink 2 is sandwiched between two platinum-plated stainless steel plates and the thickness of the ink 2 is set to 2III11, and when the two platinum-plated stainless steel plates are separated from each other with no voltage applied, neither plate It is preferable that the ink 2 adheres to the same extent.

The viscosity of the ink is 10' to 101 O poise, or even 10 at a shear rate of 10 rad/s and a temperature of 25°C.
4 to 108 poise is preferred.

The ink 2 that uses the above-mentioned mechanism is basically composed of inorganic or organic fine particles and a liquid dispersion medium. The fine particles in the ink 2 make it easier to cut the ink 2 and improve the resolution of the image. The ink 2 is a pasty or amorphous solid, and is a non-Newtonian fluid.

In order to change the adhesion of the ink 2 by applying a voltage, the ink 2 contains fine particles.

A fine particle dispersion is formed by kneading in the above-mentioned liquid dispersion medium, for example, in a homogenizer colloid mill or an ultrasonic disperser. Such particles include metal (Au, 8g, Cu, etc.) particles, sulfide (zinc sulfide, etc.)
nS, antimony sulfide Sb, S3, potassium sulfide 2
S, calcium sulfide CaS, germanium sulfide GeS
, cobalt sulfide CoS, tin sulfide SnS, iron sulfide FeS, copper sulfide Gu2S, manganese sulfide MnS, molybdenum sulfide Mo253, etc.) particles, silicic acid (orthosilicate H45iO4, metasilicate H2SiO3, mesonicic acid H2S1205, mesotrisilicate [14S i 30
3, mesotetrasilicic acid t16sI40++, etc.) particles, polyamide resin particles, polyamideimide resin particles, iron hydroxide particles, aluminum hydroxide particles, fluorinated mica particles, polyethylene particles, montmorillonite particles, fluororesins, etc. can be used. Furthermore, polymer particles containing various charge control agents used as toners for electrophotography can be used.

As a series of fine particles, those having an average particle diameter of 100 μm or less, preferably 0.1 μm to 20 μm, especially 10 μm or less, can be used. 1 part by weight or more, preferably 3 parts by weight to 90 parts by weight, more preferably 5 parts by weight
It can be contained in an amount of 60 parts by weight.

Further, the liquid dispersion medium used for ink 2 includes ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (weight average molecular weight, about 10
0-1000), ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, methyl calpitol, ethyl calpitol, butyl calpitol, ethyl calpitol acetate, diethyl calpitol, triethylene glycol monomethyl ether, triethylene Glycol monoethyl ether, propylene glycol monomethyl ether, glycerin, triethanolamine, formamide, dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, 1.3-
dimethylimidazolidinone, N-methylacetamide,
Ethylene carbonate, acetamide, succinonitrile, dimethyl sulfoxide, sulfolane, furfuryl alcohol, N,N-dimethylformamide, 2-ethoxyethanol, hexamethylphosphoric triamide (hexamethylphosphoric triamide), 2nitropropane, nitroethane, γ-butyrolactone, propylene carbonate,
1.2.6-Hexandrool, dipropylene glycol, hexylene glycol, and the like can be used alone or in combination of two of them. The liquid dispersion medium is 40 to 95 parts by weight, more preferably 60 to 95 parts by weight, based on 100 parts by weight of ink 2.
It is preferable to contain 85 parts by weight.

In a preferred embodiment, in order to control the viscosity of the ink 2, the above-mentioned polymer soluble in the liquid dispersion medium is added to the ink 2 in an amount of 1 to 90 parts by weight, more preferably 1 to 50 parts by weight, based on 100 parts by weight of the ink 2. part, especially 1 to 20 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, and casein. 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, and alginic acid-based polymers such as propylene glycol alginate and alginate. Semi-synthetic polymers such as polymers and other 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 synthetic polymers such as alkyd resins, phenolic resins, epoxy resins, aminoalkyd resins, polyester resins, polyurethane resins, acrylic resins, polyamide resins, polyamideimide resins, polyesterimide resins, silicone resins, etc., singly or in combination of two or more. Can be used. It is also possible to use greases such as silicone grease and liquid polymers such as bolybdenum.

Since the change in the adhesion of the ink 2 is caused by the generation of gas due to electrolysis, the liquid dispersion medium may be a solvent such as water, methanol, ethanol, glycerin, ethylene glycol, or propylene glycol, or potassium iodide,
A solvent in which an electrolyte such as lithium fluoroborate 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, based on 100 parts by weight of the ink 2.

In the case of the ink 2 that generates gas by electrolysis, the fine particles contained in the ink 2 include, in addition to those listed above, silica, carbon fluoride, titanium oxide, carbon black, carbon fluoride, and the like.

In a preferred embodiment of the ink 2, considering the viscoelastic properties of the ink 2, it is preferable to use swellable fine particles capable of retaining the above-mentioned liquid dispersion medium as all or part of the fine particles in the ink 2. Examples of such swellable fine particles include Na-montmorillonite, Ca-montmorillonite, 3-octahedral synthetic smectite, Na-hectrite,
Examples include fluorinated mica, synthetic mica, and silica such as Li-hectolite, Na-duolite, Na-tetrasilicic mica, and Li-duolite. The above-mentioned fluorinated mica can be represented by the following formula (1).

- Formula (1) % formula %) In the formula, W is Na or Li, X and Y are Mg'', pe2
+Niz”, Mn2-, ^l 3 +, p e
6-coordinate ions such as 3 + and l + +, Z is A
I3◆, Si'◆, Ge'◆ pe3+, B3+
or a combination thereof (^13415i4+), which represents a cation with a coordination number of 4.

The average particle diameter of the swellable fine particles is preferably 75 μm or less, more preferably 0.8 to 15 μm, and preferably 8 μl or less in a dry state.

The ink 2 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 2 contains a coloring material, the content of the coloring material is preferably 0.1 to 40 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the ink 2. Further, instead of or together with the coloring material, a coloring compound that develops color upon application of voltage may be contained. In addition, the ink 2 may contain an electrolyte that imparts conductivity, a thickener, a viscosity reducer 5 a surfactant, and the like. Furthermore, it is also possible for the above-mentioned fine particles themselves to also function as a coloring material.

In order to obtain such an ink 2, for example, a liquid dispersion medium and fine particles may be mixed by a conventional method.

In each of the embodiments described above, an example was shown in which the cylindrical ink carrying roller 1 was used as the means for transporting the ink 2.
As the means for transporting the ink 2, a belt or sheet-like ink transport member stacked in a removable manner may be used. Although this belt or sheet-like ink transport member may be edged out from one side and wound up at the other end, it is preferable to use the belt or sheet-shaped ink transfer member by turning it around by moving it endlessly.

FIG. 4 is a side view showing the main parts of a second embodiment of the present invention.

In this embodiment, the plan cylinder 5 is omitted from the embodiment shown in FIG. 1, and a negative image is recorded on the recording medium 7. For this reason, the impression cylinder 6 rotates in the direction of arrow D', opposite to that shown in FIG. Also, a water supply device 13 and an accompanying vibrator 14a.

14b is omitted. This is because most of the Joule heat generated in the ink 2 is generated in the ink layer on the ink carrier roll 1 due to its volume ratio, so even if only the ink carrier roll 1 is cooled, the ink 2 is not sufficiently cooled. This is because it becomes possible.

In this embodiment, a printed circuit board having a photoresist image on a metal plate is used as the plate 4.

4C in the figure indicates an insulating photoresist. Since the other configurations are those shown in FIG. 1, they will be given the same reference numerals and their description will be omitted. In this example, ink 2 adheres to the part of the metal substrate where there is no photoresist 4C,
An image 8 is formed on the recording paper 7. If the ink 2 is originally adhesive, the ink 2 will adhere to the photoresist 4C to form an image.

Similar to the embodiment shown in FIG. 1, cooling water is supplied to the ink carrying roll 1 from a water supply device 11 through a vibrator 12a, and is collected by a vibrator 12b.

In addition to the above, as second version 4, on a base material made of conductive material,
It is also possible to use an insulating film having an image-like conductive pattern formed by discharge breakdown. 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.

In addition, in the embodiment shown in FIGS. 1 and 4, the plate 4 is used by being wound around the cylindrical plate roll 3, but the plate 4 is used as a flat plate and used as an electrode, and ink is applied to the plate. Even if a voltage is applied with the ink sandwiched between the plate and the counter electrode,
An ink image can be formed on the plate.

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

By cooling the conductive ink, it is possible to prevent the ink from generating heat and drying out, and it is possible to ensure the stability of the image forming function.

Therefore, it is possible to realize an image forming apparatus that does not require dampening water and is easy to maintain.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the main parts of the first embodiment of the present invention, and FIG.
The figure is a drive circuit diagram of the cooling means in the first embodiment, FIG. 3 is a perspective view showing an example of the plate 4, and FIG. 4 is a side view showing main parts of the second embodiment of the present invention. It is. ! ... Ink carrying roll, la, 3a... Waterway, 2
・・・Ink, 3 axes/plate roll, 4...
Plate, 4 a-base material, 4 b... pattern, 4 cm... photoresist, 5... plan cylinder, 6... impression cylinder, 7... transfer object,
8... Ink image, 9... Coating roll, 10... Ink reservoir, 11.13... Water supply device, 12a, 12b, 14a, 14b --- Pipe, 15
...Thermistor, 15e...Pump, 10
1-...Switch.

Claims (1)

[Scope of Claims] 1. In an image forming apparatus having a coating means for coating an ink whose adhesion changes depending on the voltage application state on an original, the coating means includes an ink cooling device for cooling the ink. An image forming apparatus comprising: means.