JP2002019068A - Method and apparatus for platemaking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for ink jet platemaking capable of dealing with digital image data and clearly and rapidly printing different images on a printing medium at a low cost. SOLUTION: The method for platemaking comprises the steps of directly forming an image on a plate material by an electrostatic ink jet method for discharging an oily ink based on a signal of image data by utilizing an electrostatic field, and fixing the image to form a press plate in the apparatus comprising (1) an ink circulating system having a discharge head, an ink supply system for supplying an oily ink to the head and an ink recovery system for recovering the ink from the head and an ink tank, (2) a cleaning liquid sending system for supplying a cleaning liquid from the ink sending system, (3) and a cleaning liquid recovery system for recovering the liquid from the ink sending system. Further, the method comprises the steps of separating the tank from the sending system at the cleaning time, connecting the supply system and the recovery system to the sending system, and sending the liquid to the sending system to clean the sending system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate making method and a plate making apparatus for performing digital plate making, and more particularly, a cleaning function provided in an ink jet type ink supply system for discharging oil-based ink using an electrostatic field. The present invention relates to a plate making method and a plate making apparatus having good plate making quality and printing quality.

[0002]

2. Description of the Related Art In lithographic printing, printing ink receiving and printing ink repelling areas are provided on the surface of a printing plate corresponding to an image original, and printing is performed by adhering printing ink to the ink receiving areas. . Usually, hydrophilic and lipophilic (ink-receptive) areas are formed imagewise on the surface of the printing plate, and the hydrophilic areas are made ink-repellent by using a fountain solution.

To record an image on a printing plate (plate making), an image document is first output in analog or digital form to a silver halide photographic film, through which a diazo resin or a photopolymerizable photopolymer photosensitive material (printing plate) is printed. Is generally performed by exposing the non-image portion to elution and removal mainly using an alkaline solution.

In recent years, in the lithographic printing method, due to the recent improvement of digital drawing technology and the demand for more efficient processes,
Many systems for directly drawing digital image information on a printing plate have been proposed. This is CTP (Computer
-to-plate) or DDPP (Digital Direct Pri
nting Plate). As a plate making method, for example, there is a system for recording an image in a light mode or a heat mode using a laser, and a part of the system has begun to be put into practical use.

However, in this plate making method, in both the light mode and the heat mode, plate making is generally performed by treating with an alkaline developer after laser recording to dissolve and remove non-image portions.
Alkaline waste liquid is discharged, which is not preferable for environmental protection.

On the other hand, since the above-described method using a laser is expensive and large, a system using an ink jet method, which is an inexpensive and compact drawing apparatus, has been attempted.

Japanese Patent Application Laid-Open No. 64-27953 discloses a method of performing plate making by drawing with an ink jet using a lipophilic wax ink on a hydrophilic plate material. In this method, the image is formed with wax, so that the mechanical strength of the image portion is weak, and the adhesion to the hydrophilic surface of the printing plate is insufficient, so that the printing durability is low. Therefore, a plate making method and a plate making apparatus using an ink jet method of discharging oil-based ink using an electrostatic field have recently been spotlighted. By the way, in this ink jet method, dust adhesion and ink fixation on the discharge electrode deteriorates the discharge performance,
In addition, it has been found that the sticking of the ink in the ink circulation channel also causes a decrease in the ink flow rate and deteriorates the ejection performance. An object of the present invention is to provide a method for removing deposits in a discharge electrode and an ink circulation channel.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide, firstly, a digital plate making method and a plate making apparatus which do not require a development process. It is to be. Second, it is an object of the present invention to provide a plate making method and a plate making apparatus capable of producing a lithographic printing plate capable of obtaining a large number of clear and high-quality printed materials by an inexpensive and simple method. Thirdly, it is an object of the present invention to provide a plate making method and a plate making device capable of removing deposits in a discharge electrode and an ink circulation system flow path.

[0009]

According to a first aspect of the present invention, there is provided a plate making method according to the present invention, wherein an oil-based ink is discharged by utilizing an electrostatic field based on a signal of image data. In a plate making method for forming an image directly on a plate material by an ink-jet method and fixing the image to form a printing plate, an ink circulation system having the following a, b, and c: An ink supply system that supplies the oil-based ink to the inkjet discharge head; and an ink collection system that collects the oil-based ink from the inkjet discharge head. C, an ink tank that stores the oil-based ink, and a cleaning liquid. A cleaning liquid supply system for supplying the cleaning liquid to the ink supply system; and a cleaning unit for collecting the cleaning liquid from the ink supply system. And a liquid recovery system, at the time of cleaning,
Disconnecting the ink tank from the ink supply system, connecting the cleaning liquid supply system and the cleaning liquid recovery system to the ink supply system, and supplying cleaning liquid to the ink supply system for cleaning. Features. According to a second aspect of the present invention, in the plate making method of the first aspect, the cleaning liquid circulates during cleaning. According to a third aspect of the present invention, in the plate making method of the first or second aspect, the flow rate of the cleaning liquid during cleaning is faster than the flow rate of ink during drawing. According to a fourth aspect of the present invention, in the plate-making method according to any one of the first to third aspects, the oil-based ink is contained in a non-aqueous solvent having a specific electric resistance of 10 ⁹ Ωcm or more and a dielectric constant of 3.5 or less. At least at room temperature, wherein solid and hydrophobic resin particles are dispersed. An ink jet drawing apparatus as an image forming means for forming an image directly on a plate material by discharging an oil-based ink from a discharge head using an electrostatic field based on a signal of image data. And an image fixing unit that fixes the image formed by the image forming unit to obtain a printing plate, wherein the image forming unit includes an inkjet discharge head and the oil-based ink. An ink supply unit configured to supply ink and an ink collection unit configured to collect the oil-based ink from the inkjet discharge head; an ink tank configured to store the oil-based ink; an ink circulation unit configured to include the cleaning liquid; Cleaning liquid supply means for supplying the ink to the ink supply means, and ink supply means for supplying the cleaning liquid to the ink supply means Cleaning liquid collecting means for collecting ink from the ink supply means, a supply-side switching means for connecting the cleaning liquid supply means to the ink supply means, and the cleaning liquid collection means And a recovery-side switching means connected to the liquid sending means. According to a sixth aspect of the present invention, in the plate making apparatus of the fifth aspect, a circulating means for circulating the cleaning liquid during cleaning is provided. According to a seventh aspect of the present invention, in the plate making apparatus according to the fifth or sixth aspect, a flow rate changing unit is provided, wherein a flow rate of the cleaning liquid at the time of cleaning is higher than a flow rate of the ink at the time of drawing. The invention according to claim 8 is the plate making device according to any one of claims 5 to 7, wherein the oil-based ink is contained in a non-aqueous solvent having a specific electric resistance of 10 ⁹ Ωcm or more and a dielectric constant of 3.5 or less. At least at room temperature, wherein solid and hydrophobic resin particles are dispersed. The invention according to claim 9 is characterized in that
Wherein the image fixing means has a heat roller and / or a heating means using an infrared lamp, a halogen lamp or a xenon flash lamp. According to a tenth aspect of the present invention, in the plate making apparatus of the ninth aspect, the heating unit is arranged and / or controlled so as to gradually increase the temperature of the plate material when fixing the image. It is characterized by the following. According to an eleventh aspect of the present invention, in the plate making apparatus according to any one of the fifth to ninth aspects, at the time of drawing on the plate material, the main scanning is performed by rotating a drum on which the plate material is mounted. It is characterized by. According to a twelfth aspect of the present invention, in the plate making apparatus of the eleventh aspect, the discharge head is a single-channel head or a multi-channel head, and performs sub-scanning by moving the discharge head in the axial direction of the drum. It is characterized by the following. Claim 13
The invention described in the plate-making apparatus according to any one of claims 5 to 10, wherein at the time of drawing on the plate material, the sub-scanning is performed by nipping and running the plate material by at least a pair of capstan rollers. It is characterized by performing. According to a fourteenth aspect of the present invention, in the plate-making apparatus according to the thirteenth aspect, the discharge head comprises a single-channel head or a multi-channel head, and moves the discharge head in a direction orthogonal to a running direction of the plate material. Is used to perform main scanning. According to a fifteenth aspect of the present invention, in the plate making apparatus according to the eleventh or thirteenth aspect, the discharge head comprises a full line head having a length substantially equal to a width of the plate material. According to a sixteenth aspect of the present invention, there is provided the plate making apparatus according to any one of the fifth to fifteenth aspects, wherein dust existing on the surface of the plate material is removed before and / or during drawing on the plate material. It has a removing means. The invention according to claim 17 is the plate making device according to any one of claims 5 to 16,
The ink jet drawing apparatus has a stirring means for stirring the oil-based ink in an ink tank storing the oil-based ink. The invention according to claim 18 is the plate making apparatus according to any one of claims 5 to 17, wherein the ink jet drawing apparatus manages a temperature of the oil-based ink in an ink tank that stores the oil-based ink. It has a management means.
The nineteenth aspect of the present invention is directed to any one of the fifth to eighteenth aspects.
The plate-making apparatus according to any one of the first to third aspects, wherein the ink jet drawing apparatus has an ink density control unit for controlling the density of the oil-based ink. According to a twentieth aspect, in the plate making apparatus according to any one of the fifth to nineteenth aspects, a cleaning means for cleaning the ejection head is provided. As described above, in the ink circulation system of an ink jet type plate making apparatus that uses a static electric field to discharge oil-based ink, the cleaning liquid is switched to the cleaning liquid when cleaning the ink flow path. Deposits in the system flow path can be removed.

[0010]

Embodiments of the present invention will be described below in detail. The present invention relates to a printing plate (printing plate)
It is intended for a method of forming an image by an ink jet method in which oil-based ink is ejected by an electrostatic field.

In the present invention, the size of the ejected ink droplet is determined by the size of the tip of the ejection electrode or the conditions for forming the electric field. Therefore, by using a small ejection electrode or adjusting the electric field forming conditions, a small ink droplet can be obtained without reducing the ejection nozzle diameter or the ejection slit width. Accordingly, the present invention provides a plate making method and a plate making apparatus capable of controlling a minute image without the problem of ink clogging of a head and obtaining a printing plate capable of printing a large number of clear images.

An example of the configuration of a plate making apparatus used to carry out the plate making method of the present invention will be described below. 7 and 8 are general configuration diagrams of the plate making apparatus. FIG. 9 shows a control unit of the plate making apparatus,
3 is a schematic configuration example of a drawing unit including an ink supply unit and a head detachment mechanism. FIGS. 10 to 16 illustrate an ink jet drawing apparatus provided in the plate making apparatus shown in FIGS.

First, the plate making process according to the present invention will be described with reference to the overall configuration diagram of a plate making apparatus having a structure in which a plate material is mounted on a drawing drum 11 as shown in FIG. However, the present invention is not limited to the following configuration examples.

The drum 11 is usually made of a metal such as aluminum, stainless steel or iron, plastic, glass or the like. Particularly, in the case of a metal drum, its surface is often subjected to, for example, anodizing or chrome plating in order to enhance abrasion resistance and rust prevention. The drum 11 may have a heat insulating material on its surface as described later. Further, it is preferable that the drum 11 has a ground function as a counter electrode of the discharge head electrode in the electrostatic field discharge. On the other hand, when the insulating property of the substrate of the plate material is high, it is preferable to provide a conductive layer on the substrate. In this case, it is desirable to provide a means for grounding the conductive layer. Further, even when a heat insulating material is provided on the drum 11 as described above, drawing is facilitated by providing a means for grounding the plate material. In this case, a known means such as a brush, a leaf spring, or a roller having conductivity can be used.

Further, the plate making apparatus 1 has an ink jet drawing apparatus 2, which can
In accordance with the image data sent from the printer, an oil-based ink is ejected onto the plate material 9 mounted on the drum 11 to form an image.

The plate making device 1 has a fixing device 5 for strengthening the oil-based ink image drawn on the plate material 9. If necessary, a plate surface desensitizing device 6 used for the purpose of enhancing the hydrophilicity of the surface of the plate material 9 may be provided. In addition, the plate making apparatus 1 may be configured to print the plate material 9 before and / or during drawing on the plate material 9.
It has dust removing means 10 for removing dust present on the surface.
As a result, it is possible to effectively prevent the ink from adhering to the plate material 9 due to the dust entering between the head and the plate material during plate making,
Good plate making is performed. As the dust removing means 10, in addition to a known non-contact method such as suction removal, blowing removal, and electrostatic removal, a contact method using a brush, a roller, or the like can be used. In the present invention, any of air suction and air blowing is preferable. Or a combination thereof.

Further, an automatic plate feeding device 7 for automatically supplying the plate material 9 onto the drum 11 and an automatic plate discharging device 8 for automatically removing the plate material 9 from the drum 11 after drawing are provided. Good. The use of the automatic plate feeding device 7 and the automatic plate discharging device 8 makes the plate making operation easier and shortens the plate making time, so that the effects of the present invention can be further enhanced.

Referring to FIG. 7 and a part of FIG.
The process of producing a printing plate according to the above will be described below.

First, the plate material 9 is mounted on the drum 11 using the automatic plate feeding device 7. At this time, the plate material 9 is closely fixed on the drum 11 by a mechanical method using a known plate head / butt holding device, an air suction device, or the like, or the like. It is possible to prevent the ink jet drawing apparatus 2 from being damaged at the time of contact. In addition, the plate material 9 is formed only around the drawing position of the ink jet drawing apparatus 2.
The plate member 9 can be prevented from coming into contact with the ink jet drawing apparatus 2 by providing a means for bringing the plate material 9 into close contact with the drum 11 and acting at least when drawing is performed. Specifically, for example, there is a method of disposing a pressing roller upstream and downstream of the drawing position on the drum 11. Further, when the drawing is not performed, it is desirable to keep the head away from the plate material, which can effectively prevent the ink jet drawing apparatus 2 from suffering a problem such as contact damage.

The image data arithmetic control unit 21 receives image data from an image scanner, a magnetic disk device, an image data transmission device, etc., performs color separation as necessary, Divide calculation into number and gradation number. Furthermore, in order to draw an oil-based ink image in a halftone manner using the inkjet discharge head 22 (see FIG. 9 and described in detail later) included in the inkjet drawing apparatus 2, a calculation of a dot area ratio is also performed. Also, as described below,
The image data calculation control unit 21 controls the movement of the inkjet discharge head 22 and the discharge timing of the oil-based ink, and also controls the operation timing of the drum 11 and the like as necessary. The calculation data input to the image data calculation control unit 21 is temporarily stored in a buffer. The image data calculation control unit 21 rotates the drum 11 and
Is brought closer to the position close to the drum 11 by the head separation / contact device 31. Discharge head 22 and plate 9 on drum 11
The distance from the surface is controlled to a predetermined distance during drawing by mechanical distance control such as an abutment roller, or control of a head separation / contact device by a signal from an optical distance detector. By such distance control, good plate making can be performed without the dot diameter becoming non-uniform due to the floating of the plate material or the dot diameter not changing even when vibration is applied to the plate making machine.

A single-channel head, a multi-channel head, or a full-line head can be used as the ejection head 22, and the main scanning is performed by the rotation of the drum 11. In the case of a multi-channel head having a plurality of discharge units or a full line head, the arrangement direction of the discharge units is set in the axial direction of the drum 11. Further, in the case of a single-channel head or a multi-channel head, the discharge head 22 is moved in the axial direction of the drum 11 by one rotation of the drum 11 by the image data calculation control unit 21 to obtain the discharge position and the net obtained by the above calculation. The oil-based ink is discharged onto the plate material 9 mounted on the drum 11 at a point area ratio. As a result, a halftone image corresponding to the density of the print document is drawn on the plate material 9 with the oil-based ink. This behavior is
An oil-based ink image for one color of the printing original is formed on the plate material 9 and continues until a printing plate is completed. On the other hand, when the ejection head 22 is a full line head having a length substantially equal to the width of the drum 11, one rotation of the drum 11 forms an oil-based ink image of one color of a printing document on the plate 9. A printing plate is completed. By performing the main scanning by rotating the drum 11 in this manner, the positional accuracy in the main scanning direction can be improved, and high-speed drawing can be performed.

Next, in order to protect the discharge head 22, the discharge head 22 is retracted away from a position close to the drum 11. This separation / contact means operates so that the ejection head is separated from the drum by at least 500 μm except during drawing. The separation / contact operation may be performed by a slide type, or the ejection head 22 may be fixed by an arm fixed to a certain axis, and the arm may be moved around the axis to move like a pendulum. By retracting the ejection head 22 during non-drawing in this way, the ejection head 22 can be protected from physical damage or contamination, and a long life can be achieved.

Further, the formed oil-based ink image is reinforced by the fixing device 5. As a means of fixing ink,
Known means such as heat fixing and solvent fixing can be used. In the heat fixing, irradiation with an infrared lamp, a halogen lamp, a xenon flash lamp, hot air fixing using a heater, and heat roll fixing are generally used. In this case, the drum 9 is heated in order to enhance the fixing property.
Is heated in advance, drawing is performed while applying hot air, the drum 11 is coated with a heat insulating material, and the drum 11 is fixed at the time of fixing.
It is effective to take measures such as separating the plate material 9 from the substrate and heating only the plate material 9 alone or in combination.
Flash fixing using a xenon lamp or the like is known as a method for fixing electrophotographic toner, and has an advantage that fixing can be performed in a short time. Also, when using paper plates,
The water inside the plate evaporates rapidly due to the rapid temperature rise,
Since a phenomenon called blister, in which irregularities occur on the plate material surface, occurs, the drum 1 is heated so that the temperature of the paper plate material gradually increases.
It is preferable to gradually increase the power supply to the heat source while rotating 1, or to change the rotation speed from high speed to low speed with constant power supply. Alternatively, the paper plate material may be gradually heated by disposing a plurality of fixing units in the rotation direction of the drum 11 and changing the distance to the plate material 9 and / or the supplied power.

In solvent fixing, a solvent capable of dissolving the resin component in the ink, such as methanol or ethyl acetate, is sprayed or exposed to steam, and excess solvent vapor is recovered. In addition, at least in the process from the formation of the oil-based ink image by the ejection head 22 to the fixing by the fixing device 5, it is desirable that nothing is kept in contact with the image on the plate material 9.

A configuration example of a plate making apparatus for performing sub-scanning by moving the plate material 9 will be described with reference to FIG. However, the present invention is not limited to the following configuration examples.

The plate material 9 includes two pairs of capstan rollers 1
2, and the image is drawn by the ink jet drawing apparatus 2 using the data divided and calculated by the image data calculation control unit 21 into an appropriate number of pixels and gradations. It is preferable that a grounding means 13 is provided at a portion where drawing is performed by the ink jet drawing device 2 so as to be a counter electrode of the discharge head electrode in electrostatic field discharge, thereby facilitating drawing. On the other hand, when the insulating property of the base of the plate 9 is high, it is preferable to provide a conductive layer on the base. In this case, the conductive layer is formed on the conductive layer by means of a known conductive brush, leaf spring, roller or the like. It is desirable to take the ground.

FIG. 8 shows an apparatus using a sheet plate material, but a roll plate material is also suitably used. In this case, it is desirable to provide a sheet cutter upstream of the automatic plate discharging device. Further, the plate making apparatus has the ink jet drawing apparatus 2, and the
An oil-based ink is discharged onto the plate material 9 to form an image in accordance with the image data sent from the printer.

The plate making device 1 has a fixing device 5 for strengthening the oil-based ink image drawn on the plate material 9. A plate surface desensitizing device 6 used as needed for the purpose of enhancing the hydrophilicity of the surface of the plate material 9 may be provided. In addition, the plate making apparatus 1 includes dust removing means 10 for removing dust existing on the plate material surface before and / or during drawing on the plate material 9. Accordingly, it is possible to effectively prevent ink from adhering to the plate material by transmitting dust between the discharge head and the plate material during plate making, and perform good plate making. As the dust removing means 10, in addition to a known non-contact method such as suction removal, blowing removal, and electrostatic removal,
A contact method using a brush, a roller, or the like can be used, and in the present invention, it is preferable to use either air suction or air blowing, or a combination thereof.

Further, it is preferable to provide an automatic plate feeding device 7 for automatically supplying the plate material 9 and an automatic plate discharging device 8 for automatically removing the plate material 9 after drawing. The use of the automatic plate feeding device 7 and the automatic plate discharging device 8 makes the plate making operation easier and shortens the plate making time, so that the effects of the present invention can be further enhanced.

Referring to FIG. 8 and partly in FIG.
Will be described in more detail below.

First, the plate material 9 is transported using the automatic plate feeding device 7 and the cap stun roller 12. At this time, if necessary, by providing a plate material guide means or the like (not shown), it is possible to prevent the plate head / tail of the plate material from fluttering and coming into contact with the ink jet drawing apparatus 2 and being damaged. In addition, means for preventing the plate material 9 from being loosened only around the drawing position of the ink jet drawing device 2 is provided to prevent the plate material 9 from contacting the ink jet drawing device 2 at least when drawing is performed. You can also.
Specifically, for example, there is a method of arranging a pressing roller upstream and downstream of the drawing position. Further, when the drawing is not performed, it is desirable to keep the ejection head away from the plate material 9, which can effectively prevent the ink jet drawing apparatus 2 from causing troubles such as contact damage.

Image data from a magnetic disk device or the like
The image data calculation control unit 21 is provided with the image data calculation control unit 21 and calculates the ejection position of the oil-based ink and the halftone dot area ratio at that position in accordance with the input image data. These calculation data are temporarily stored in the buffer. The image data calculation control unit 21 controls the movement of the ejection head 22, the ejection timing control of the oil-based ink, and the operation timing control of the capstan roller. Move closer to the close position. The distance between the ejection head 22 and the surface of the plate material 9 was maintained at a predetermined distance during drawing by mechanical distance control such as a contact roller or control of a head separation / contact device by a signal from an optical distance detector. It is. By such distance control, good plate making can be performed without the dot diameter becoming non-uniform due to the floating of the plate material or the dot diameter not changing even when vibration is applied to the plate making machine.

As the discharge head 22, a single-channel head, a multi-channel head, or a full-line head can be used. In the case of a multi-channel head having a plurality of ejection portions, the arrangement direction of the ejection portions is set substantially parallel to the traveling direction of the printing plate. Further, in the case of a single-channel head or a multi-channel head, the ejection head 22 is moved by the image data calculation control unit 21 in the direction orthogonal to the traveling direction of the plate material 9 every time the plate material is moved, and the ejection obtained by the above calculation is performed. Plate material 9 with oil-based ink at position and dot area ratio
To be discharged. As a result, a halftone image corresponding to the density of the print document is drawn on the plate material 9 with the oil-based ink. This operation continues until an oil-based ink image for one color of the printing original is formed on the plate material 9 and the printing plate is completed. On the other hand, the ejection head 22
Is a full line head having substantially the same length as the width of the plate material 9, the arrangement direction of the discharge units is set to a direction substantially orthogonal to the traveling direction of the plate material, and the plate material 9 passes through the drawing unit. By doing so, an oil-based ink image for one color of the printing original is formed on the plate material 9, and a printing plate is completed.

In order to protect the discharge head 22, it is preferable that the discharge head 22 is retracted away from a position close to the plate material 9. This separation / contact means operates so that the ejection head is separated from the plate material 9 by at least 500 μm except during drawing. The separation / contact operation may be performed by a slide type, or the ejection head may be fixed by an arm fixed to a certain axis, and the arm may be moved around the axis to move like a pendulum. By retracting the ejection head during non-drawing in this way, the ejection head can be protected from physical damage or contamination, and a long life can be achieved.

Further, the formed oil-based ink image is reinforced by the fixing device 5. As a means of fixing ink,
Known means such as heat fixing and solvent fixing can be used. In the heat fixing, irradiation with an infrared lamp, a halogen lamp, a xenon flash lamp, hot air fixing using a heater, and heat roll fixing are generally used. Flash fixing using a xenon lamp or the like is known as a method for fixing electrophotographic toner, and has an advantage that fixing can be performed in a short time. Also, when using a paper plate material, a phenomenon called blister occurs, in which the water inside the plate material evaporates rapidly due to a rapid temperature rise, and irregularities are generated on the plate material surface.
It is preferable to dispose a plurality of fixing devices and change the power supply and / or the distance of the fixing device to the plate material 9 so as to gradually increase the temperature of the paper plate material in order to prevent blisters of the plate material 9. .

In solvent fixing, a solvent capable of dissolving the resin component in the ink, such as methanol or ethyl acetate, is sprayed or exposed to steam, and excess solvent vapor is recovered. In addition, at least in the process from the formation of the oil-based ink image by the ejection head 22 to the fixing by the fixing device 5, it is desirable that nothing is kept in contact with the image on the plate material 9.

The printing plate obtained is printed by a known lithographic printing method. That is, the printing plate on which the oil-based ink image is formed is mounted on a printing press, a printing ink and dampening water are applied to form a printing ink image, and the printing ink image is formed on a blanket cylinder rotating with the plate cylinder. Printing is performed, and then printing of one color is performed by transferring the printing ink image on the blanket cylinder onto printing paper passing between the blanket cylinder and the impression cylinder. After the printing is completed, the printing plate is removed from the plate cylinder, and the blanket on the blanket cylinder is cleaned by the blanket cleaning device, and is ready for the next printing.

Next, the ink jet drawing apparatus 2 will be described. As shown in FIG. 9, the ink jet drawing apparatus 2 used in the plate making apparatus includes an ink jet discharge head 22 and an ink supply unit 24. Ink supply unit 2
Reference numeral 4 further includes an ink tank 25, an ink supply device 26, and an ink concentration control unit 29. The ink tank 25 includes a stirring unit 27 and an ink temperature management unit 28. The ink may be circulated in the ejection head 22, and in this case, the ink supply unit 24 also has a recovery circulation function. Stirring means 27
Reduces the precipitation and aggregation of the solid components of the ink, thereby reducing the necessity of cleaning the ink tank 25. As the stirring means 27, a rotary blade, an ultrasonic vibrator, and a circulation pump can be used, and these are used or in combination. The ink temperature management unit 28 is arranged so that a high-quality image can be stably formed without changing the physical properties of the ink due to a change in ambient temperature and without changing the dot diameter. As the ink temperature control means, a heater, a heating element such as a Peltier element, or a cooling element is arranged in the ink tank 25 together with the stirring means 27 so as to keep the temperature distribution in the ink tank 25 constant, and a temperature sensor, for example, A known method such as control using a thermostat or the like can be used.
The temperature of the ink in the ink tank 27 is 15 ° C. or more and 60 ° C.
C. or less, more preferably 20.degree. C. or more and 50.degree. C. or less. Further, the stirring means for keeping the temperature distribution in the ink tank 25 constant may be shared with the stirring means for suppressing the precipitation and aggregation of the solid components of the ink.

In addition, the plate making apparatus preferably has an ink density control means 29 in order to perform high-quality drawing. As a result, it is possible to effectively suppress the occurrence of bleeding on the plate due to a decrease in the solid concentration in the ink, the jump or blur of the printed image, or the change in the dot diameter on the plate due to the increase in the solid concentration. The ink concentration is measured by optical detection, physical property measurement such as conductivity measurement, viscosity measurement, or management based on the number of drawn images. In the case of performing management by physical property measurement, an optical detector, a conductivity measuring instrument, and a viscosity measuring instrument are provided alone or in combination in the ink tank 25 or the ink flow path, and drawing is performed by an output signal thereof. In the case of performing management by the number of sheets, the supply of liquid from a replenishing concentrated ink tank or a diluting ink carrier tank (not shown) to the ink tank 25 is controlled according to the number of plate making and the frequency.

As described above, the image data calculation control unit 21 calculates the input image data, and controls the head separation / contact device 31,
Alternatively, in addition to moving the ejection head 22 by the head sub-scanning means 32, a timing pulse from the encoder 30 provided on the drum 11 or the capstan roller is taken in, and the ejection head 22 is driven according to the timing pulse. Thereby, the position accuracy can be improved.

Next, the ejection head 22 will be described with reference to FIGS. However, the content of the present invention is not limited to the following.

FIGS. 10 and 11 show an example of the discharge head provided in the ink jet drawing apparatus. The ejection head 22 has a slit sandwiched between an upper unit 221 and a lower unit 222 made of an insulating base material, the tip of which is an ejection slit 22a, and an ejection electrode 22b is arranged in the slit. The slit 23 is filled with the ink 23 supplied from the ink supply device. As the insulating base material, for example, plastic, glass, ceramics, etc. can be applied. The discharge electrode 22
b, aluminum, nickel, chromium, gold, a conductive material such as platinum is vacuum-deposited, sputtered, or electroless-plated on the lower unit 222 made of an insulating base material, and a photoresist is applied thereon, Exposing and developing a photoresist through a mask of a predetermined electrode pattern, forming a photoresist pattern of the discharge electrode 22b, and then etching or mechanically removing the photoresist pattern, or a method combining them It is formed by a known method.

As shown in FIG. 10, the ejection head 22
The drum 11 serving as a counter electrode is provided at a position facing the discharge electrode 22b provided on the substrate, and the plate material 9 is provided on the drum 11 serving as the counter electrode. When a voltage is applied to the discharge electrode 22b according to the digital signal of the pattern information of the image, a circuit is formed between the discharge electrode 22b and the drum 11 serving as a counter electrode, and the oil-based ink 23 is discharged from the discharge slit 22a of the head 22. An image is formed on the plate material 9 provided on the drum 11 which is discharged and becomes a counter electrode.

It is preferable that the width of the discharge electrode 22b is as narrow as possible in order to form a high quality image. Specific numerical values vary depending on conditions such as applied voltage and ink physical properties, but are usually used in a range of a tip width of 5 to 100 μm. For example, a discharge electrode 22b having a tip of 20 μm width is used, a distance between the discharge electrode 22b and the drum 11 serving as a counter electrode is set to 1.0 mm, and a voltage of 3 KV is applied between the electrodes for 0.1 millisecond to form a dot of 40 μm. To plate material 9
Can be formed on.

FIGS. 12 and 13 are a schematic sectional view and a schematic front view, respectively, showing the vicinity of the ink discharge portion of another discharge head. In the figure, reference numeral 22 denotes a discharge head, which is a first insulating base material 33 having a gradually decreasing shape.
have. A second insulating substrate 34 is provided on the first insulating substrate 33 so as to be spaced apart and opposed to the first insulating substrate 33, and a slope portion 35 is formed at the tip of the second insulating substrate 34.
The first and second insulating substrates are made of, for example, plastic, glass, ceramics, or the like. A plurality of ejection electrodes 22b are provided on an upper surface 36 of the second insulating base 34, which forms an acute angle with the inclined surface 35, as an electrostatic field forming means for forming an electrostatic field in the ejection portion. The tips of the plurality of ejection electrodes 22b extend to near the tips of the upper surface portion 36, and the tips protrude forward of the first insulating base material 33 to form ejection portions.
An ink inflow path 3 is provided between the first and second insulating bases 33 and 34 as a means for supplying the ink 23 to the discharge section.
7 is formed, and an ink recovery path 38 is formed below the second insulating base material 34. The ejection electrode 22
b is formed by using a conductive material such as aluminum, nickel, chromium, gold, or platinum on the second insulating base material 34 by a known method as described above. Individual electrode 22b
Are electrically insulated from each other.

The amount by which the tip of the discharge electrode 22b projects from the tip of the insulating substrate 33 is preferably 2 mm or less. The reason that the protrusion amount is preferable in the above range is that if the protrusion amount is too large, the ink meniscus does not reach the tip of the discharge unit,
This is because the ejection becomes difficult and the recording frequency decreases. The space between the first and second insulating bases 33 and 34 is preferably in the range of 0.1 to 3 mm. The reason that this space is preferable in the above range is that if the space is too narrow, it becomes difficult to supply ink and it becomes difficult to discharge, or the recording frequency is lowered, and if the space is too wide, the meniscus is not stable. This is because the ejection becomes unstable.

The ejection electrode 22b is connected to the image data calculation control section 21. When recording, the ink on the ejection electrode is ejected by applying a voltage to the ejection electrode based on the image information. Drawing is performed on a plate material (not shown) arranged opposite to the plate material. The direction opposite to the ink droplet ejection direction of the ink inflow path 37 is connected to an ink feeding unit of an ink supply device (not shown). The second insulating substrate 3
A backing 39 is provided on the surface opposite to the ejection electrode forming surface of No. 4 so as to be spaced apart and opposed, and an ink recovery path 38 is provided between the two. The space of the ink recovery path 38 is 0.1
mm or more is desirable. The reason why this space is preferable in the above range is that if the space is too narrow, it becomes difficult to collect the ink, which may cause ink leakage. The ink recovery path 38 is connected to an ink recovery means of an ink supply device (not shown).

When a uniform ink flow on the ejection section is required, a groove 40 may be provided between the ejection section and the ink recovery section. FIG. 13 is a schematic front view of the vicinity of the ink ejection portion of the ejection head, and a plurality of grooves are formed on the slope of the second insulating base 34 from near the boundary with the ejection electrode 22 b toward the ink recovery path 38. 40 are provided. A plurality of the grooves 40 are arranged in the arrangement direction of the ejection electrodes 22b, and a certain amount of ink near the tip of the ejection electrode is guided from the opening on the ejection electrode 22b side by a capillary force according to the opening diameter. A function of discharging the discharged ink to the ink recovery path 38. For this reason, it has a function of forming an ink flow having a constant liquid thickness near the tip of the discharge electrode. The shape of the groove 40 may be any range as long as the capillary force acts, and particularly preferably, the width is 10 to 200 μm and the depth is 10 to 300 μm.
It is in the range of μm. The necessary number of grooves 40 are provided so that a uniform ink flow can be formed over the entire surface of the ejection head.

The width of the discharge electrode 22b is preferably as narrow as possible in order to form a high quality image. Specific numerical values vary depending on conditions such as applied voltage and ink physical properties, but are usually used in a range of a tip width of 5 to 100 μm.

Another example of the ejection head used to carry out the present invention is shown in FIGS. FIG. 14 is a schematic view showing only a part of the head for the purpose of explanation. As shown in FIG. , 42 '. In the drawing, reference numeral 22b denotes an ejection electrode for applying a voltage to form an electrostatic field in the ejection section. Further, the head body will be described in detail with reference to FIG.

The head main body 41 is provided with a plurality of ink grooves 43 for circulating ink perpendicular to the edge of the head main body. The shape of the ink groove 43 may be set in a range where the capillary force acts so that a uniform ink flow can be formed, and particularly preferably, the width is 10 to 200 μm.
m, the depth is 10 to 300 μm. The ejection electrode 22b is provided inside the ink groove 43. The ejection electrode 22b is formed on a head body 40 made of an insulating material by using a conductive material such as aluminum, nickel, chromium, gold, or platinum by a known method similar to that of the above-described apparatus embodiment. It may be arranged on the entire surface in the groove 43 or may be formed only on a part thereof. The discharge electrodes are electrically isolated. Two adjacent ink grooves form one cell, and ejection parts 45 and 45 'are provided at the end of the partition wall 44 at the center. In the discharge portions 45 and 45 ', the partition walls are thinner than the other partition portions 44 and are sharpened. Such a head body is formed by a known method such as machining, etching, or molding of an insulating material block. The thickness of the partition wall at the discharge portion is preferably 5 to 100 μm, and the radius of curvature of the sharpened tip is preferably 5 to 50 μm. The tip of the discharge section may be slightly chamfered as in 45 '. Although only two cells are shown in the figure, the cells are separated by a partition wall 46, and the front end portion 47 is chamfered so as to be retracted from the discharge portions 45 and 45 '.
Ink is supplied to the ejection head from an I direction through an ink groove by an ink sending means of an ink supply device (not shown) to supply the ink to the ejection unit. Further, surplus ink is collected in the O direction by an ink collecting unit (not shown), and as a result, fresh ink is always supplied to the ejection unit. In this state, a voltage is applied to a discharge electrode (not shown) holding a plate material on the surface thereof in accordance with image information in accordance with image information. An image is formed on the material.

Another embodiment of the ejection head will be described with reference to FIG. As shown in FIG. 16, the ejection head 22 has a pair of substantially rectangular plate-shaped support members 50 and 50 '. These support members 50, 50 'are made of a plate-like plastic, glass, ceramic or the like having a thickness of 1 to 10 mm having an insulating property, and one surface of each is parallel to each other according to the recording resolution. Each of the grooves 51, 5 is formed with a plurality of elongated rectangular grooves 51, 51 '.
1 'preferably has a width of 10 to 200 [mu] m and a depth of 10 to 300 [mu] m, and the discharge electrode 22b is formed entirely or partially inside. As described above, by forming a plurality of structures 51, 51 'on one surface of the support members 50, 50', a plurality of rectangular partition walls 52 are inevitably provided between the structures 51. Each support member 50, 50 '
Are combined so that the surfaces on which the grooves 51 and 51 'are not formed face each other. That is, the ejection head 22 has a plurality of grooves on the outer peripheral surface for flowing ink.
Grooves 51, 51 'formed in each support member 50, 50'
Are connected in a one-to-one correspondence via a rectangular portion 54 of the ejection head 22, and the rectangular portion 54 to which each groove is connected is a predetermined distance (50 to 500 μm) from the upper end 53 of the ejection head 22.
m) has receded. That is, on both sides of each rectangular portion 54, the upper end 55 of each partition 52 of each support member 50, 50 '.
Are provided so as to protrude from the rectangular portion 54. A guide projection 56 made of an insulating material as described above is provided so as to protrude from each rectangular portion 54 to form a discharge portion.

When the ink is circulated through the discharge head 22 configured as described above, the ink is supplied to each rectangular portion 54 through each groove 51 formed on the outer peripheral surface of one of the support members 50, and is supplied to the opposite side. Each groove 5 formed in the supporting member 50 '
Discharge via 1 '. In this case, the ejection head 22 is inclined at a predetermined angle to enable smooth ink distribution. In other words, the ejection head 22 is inclined such that the ink supply side (support member 50) is located above and the ink discharge side (support member 50 ') is located below.
As described above, when the ink is circulated through the ejection head 22,
The ink passing through each rectangular portion 54 wets along each protrusion 56, and an ink meniscus is formed near the rectangular portion 54 and the protrusion 56. Then, in a state where independent ink meniscuses are formed in the respective rectangular portions 54,
Ink is ejected from the ejection unit to apply a voltage to the ejection electrode 22b based on image information to a drum (not shown) holding the plate material on the surface thereof, and the ink is ejected from the ejection unit onto the plate material. An image is formed. By providing a cover for covering the groove on the outer peripheral surface of each support member 50, 50 ', a pipe-shaped ink flow path is formed along the outer peripheral surface of each support member 50, 50'. May be forcibly circulated. In this case, it is not necessary to tilt the ejection head 22.

The ejection head 22 described above with reference to FIGS.
May include a maintenance device such as a cleaning unit as necessary. For example, if the pause state continues or if a problem occurs in image quality, the tip of the ejection head is brushed with a flexible brush, brush, cloth, or the like, circulates only the ink solvent, supplies only the ink solvent, Alternatively, a good drawing state can be maintained by performing means such as sucking the discharge unit while circulating the ink alone or in combination. In order to prevent the ink from sticking, it is effective to cool the head and suppress evaporation of the ink solvent. If the contamination is further severe, the ink is forcibly sucked from the ejection section, the jet of air, ink, or ink solvent is forcibly injected from the ink flow path, or the ultrasonic wave is applied while the head is immersed in the ink solvent. Is also effective, and these methods can be used alone or in combination. Furthermore, it has been found that it is also effective to supply a cleaning liquid to the ink flow path when cleaning the ink flow path in the ink circulation system of the plate making apparatus.

FIG. 1 shows a first embodiment of the present invention in which ink is changed from a cleaning liquid to a cleaning liquid when cleaning an ink flow path in an ink circulation system of a plate making apparatus for forming a single-color image on a roll-shaped plate material. This is an example of a cleaning liquid non-circulation type using a pump pressure feeding circulation system. In FIG. 1, 101 is a head, 102, 103,
Is a liquid sending pump, 104 is an ink concentration control means, 105,
106 is a three-way valve, 107, 114, 115 and 116 are valves, 108 is a cleaning liquid tank, 109 is an ink tank, 110 is a waste liquid tank, 111 is a stirring means, 112
Denotes an ink temperature management unit, and 113 denotes a tray.

(1) Non-circulating type of cleaning liquid (pump pressure circulation type) Cleaning pattern 1: During cleaning, the valve 107 is opened and the valve 114 is closed. The three-way valve 105 is set to the cleaning liquid tank 108 side. The three-way valve 106 is set on the waste liquid tank 110 side. By switching the valve 115 to the closed side, the cleaning liquid flows to the waste liquid tank 110 side, and the ink flow path (between the three-way valve 105 and the head 101 and between the head 101 and the three-way valve 106) and the discharge part (electrode) of the head 101 To clean. The cleaning liquid is discharged to the waste liquid tank 110. (At this time, the valve 116 is normally open.)

Cleaning pattern 2: The above-mentioned cleaning pattern 1
Further, the flow rates of the liquid sending pumps 102 and 103 are increased. That is, at the time of cleaning, the valve 107 is opened and the valve 114 is closed. The three-way valve 105 is set to the cleaning liquid tank 108 side. 3 way valve 106 to waste liquid tank 1
Set to 10 side. By switching the valve 115 to the closed side, the cleaning liquid flows to the waste liquid tank 110 side, and the ink flow path (between the three-way valve 105 and the head 101 and between the head 101 and the three-way valve 106) and the discharge part (electrode) of the head 101 To clean. The cleaning liquid is discharged to the waste liquid tank 110 (the valve 116 is always open). At this time, the flow rates and flow rates of the liquid sending pumps 102 and 103 are increased. Thereby, the cleaning effect can be improved.

Cleaning pattern 3: Cleaning pattern 1
Further, the discharge amount of only the liquid sending pump 102 is increased.
That is, at the time of cleaning, the valve 107 is opened and the valve 114 is opened.
Close. The three-way valve 105 to the cleaning liquid tank 108
To the side. The three-way valve 106 is set on the waste liquid tank 110 side.
By switching the valve 115 to the closed side, the cleaning liquid flows to the waste liquid tank 110 side, and the ink flow path (the three-way valve 1)
05-head 101, and head 101-three-way valve 1
06) and the ejection portion (electrode) of the head 101 is cleaned. The cleaning liquid is discharged to the waste liquid tank 110 (the valve 116 is always open). At this time, the discharge amount of only the liquid sending pump 102 is increased. As a result, the cleaning liquid leaks from the head discharge section, and the tip of the head discharge section is cleaned, so that more effective cleaning can be performed. The leaked cleaning liquid is discharged to the waste liquid tank 110 via the tray 113.

At the time of stopping: The valves 107 and 116 are switched to the closed side almost simultaneously with stopping the liquid feeding pumps 102 and 103 from the above-mentioned cleaning patterns 1 to 3. As a result, the cleaning is stopped in a state in which the liquid sending system is filled with the cleaning liquid, so that the liquid sending system is kept clean. In the above case, the three-way valve 106 is switched at the time of cleaning.
By further delaying, the outflow of the ink to the waste liquid tank 110 can be reduced. It is best to switch immediately before the cleaning liquid reaches the three-way valve 106. The timing t (second) is determined by the pumps 102, 1
Since equation (1) is established from the liquid supply amount Q per second Q, the radius r in the pipe, and the pipe length L of 03, the equation (2) can be easily calculated therefrom. Q · t = L · πr ² (1) t = L · πr ² / Q (2)

FIG. 2 shows a second embodiment of the present invention, which is an example of a cleaning liquid circulation type using a pump pressure circulation system. In FIG. 2, 201 is a head, 202, 2
03 is a liquid feed pump, 204 is an ink density control means, 20
5, 206, 214 are three-way valves, 207, 215, 21
6, 217 are valves, 208 is a cleaning liquid tank, 20
9 is an ink tank, 210 is a waste liquid tank, 211 is a stirring means, 212 is an ink temperature management means, and 213 is a tray.

(2) Cleaning liquid circulation type (pump pressure circulation system) Cleaning pattern 1: During cleaning, the valve 207 is opened and the valve 215 is closed. The three-way valve 205 is set to the cleaning liquid tank 208 side. The three-way valve 206 is switched to the waste liquid tank 210 side, and the valve 216 is closed. At this time, the three-way valve 214 is still on the waste liquid tank 210 side. At a timing such that the cleaning liquid passing through the three-way valve 214 becomes clean, the three-way valve 214 is switched to the cleaning liquid tank 208 side to circulate the cleaning liquid. At this time, the valve 217 is always open.

Cleaning pattern 2: Cleaning pattern 2 is to increase the flow rates of the liquid sending pumps 202 and 203 to the above-mentioned "cleaning pattern 1". That is, at the time of cleaning, the valve 207 is opened, the valve 215 is closed, and the three-way valve 205 is opened.
To the cleaning liquid tank 208 side. Further, the three-way valve 206 is switched to the waste liquid tank 210 side, and the valve 216 is closed. At this time, the three-way valve 214 is still on the waste liquid tank 210 side. At a timing such that the cleaning liquid passing through the three-way valve 214 becomes clean, the three-way valve 214 is switched to the cleaning liquid tank 208 side to circulate the cleaning liquid. The valve 217 is normally open. At this time, the flow rates and flow rates of the liquid sending pumps 202 and 203 are increased. Thereby, the cleaning effect can be improved.

Cleaning pattern 3: Cleaning pattern 1
Further, the discharge amount of only the liquid sending pump 202 is increased. In other words, this allows the cleaning liquid to leak from the head discharge unit 201, thereby enabling more effective cleaning than the head discharge unit. The leaked cleaning liquid is transferred to the pan 2
13, and is discharged to the waste liquid tank 210. It is more effective to perform this pattern 3 at the start of cleaning and at the end of cleaning.

At the time of stop: from the above-mentioned patterns 1 to 3,
Almost simultaneously with the stop of the liquid sending pumps 202 and 203, the valve 20
7, 217 are closed. As a result, the cleaning is stopped in a state in which the liquid sending system is filled with the cleaning liquid, so that the liquid sending system is kept clean. In the above case, the switching of the three-way valve 206 at the time of cleaning is delayed after the three-way valve 205, so that the outflow of the ink to the waste liquid tank 210 can be reduced. It is best to switch immediately before the cleaning liquid reaches the three-way valve 206. The timing is the same as described above.

(3) Non-circulating Cleaning Liquid (Hydrostatic Circulation System) FIG. 3 shows a third embodiment of the present invention, which is an example of a non-circulating cleaning liquid using a hydrostatic circulation system. .
In FIG. 3, reference numeral 301 denotes a head, 302 and 303 denote a liquid feed pump, 304 denotes an ink density control unit, and 305 and 30.
Reference numerals 6 and 314 denote three-way valves, and the three-way valve 314 is for switching between the overflow liquid ink tank 309 side and the waste liquid tank 310 side. 307, 315, 316, 317 are valves, 3
08 is a cleaning liquid tank, 309 is an ink tank,
310 is a waste liquid tank, 311 is a stirring means, 312 is an ink temperature management means, and 313 is a hydrostatic tank. In this hydrostatic pressure method, a hydrostatic tank 313 storing ink is installed on a vertically moving table, and the hydrostatic tank 313 is
This is a method of adjusting the static ink pressure applied to the head 301 by raising and lowering the pressure, and has a feature that the liquid pressure applied to the head 301 does not pulsate.

At the time of cleaning, the valve 307 is opened and the valve 31 is opened.
5 is closed, and the three-way valve 305 is
Side, the three-way valves 306, 314 to the waste liquid tank 310 side,
By switching the valve 316 to close, the ink flow path (between the three-way valve 305 and the hydrostatic pressure tank 313 and the head 301, the overflow portion of the hydrostatic pressure tank 313, and the three-way valve 314
The cleaning liquid is caused to flow by cleaning fluid between the head 301 and the three-way valve 306) and the discharge part (electrode) of the head 301.

When the apparatus is stopped, the pumps 307 and 31 are stopped almost simultaneously with the stop of the liquid supply pumps 302 and 303 from the above-mentioned washing state.
Switch 7 to closed.

(4) Cleaning Liquid Circulation Type (Hydrostatic Pressure Circulation System) FIG. 4 shows a fourth embodiment of the present invention, and is an example of a cleaning liquid circulation type using a hydrostatic pressure circulation system. In FIG. 4, reference numeral 401 denotes a head, 402 denotes a feed side, and 40 denotes a head.
Numeral 3 denotes each liquid feed pump on the return side, 404 denotes an ink density control means, 405, 406, 413, 415, and 416 denote three-way valves, a three-way valve 405 switches ink / cleaning liquid on the feed side, and a three-way valve 406 returns. Side ink tank 409
The three-way valve 413 is for switching between the cleaning liquid tank 408 and the waste liquid tank 410 and the three-way valve 4 for switching the cleaning liquid destination.
Numeral 15 is for switching the overflow liquid to the ink tank 409 side / waste liquid tank 410 side, and three-way valve 416 is for switching the destination of the overflow cleaning liquid to switch between the cleaning liquid tank 408 side and the waste liquid tank 410 side. 407, 417, 418, 419 are valves. 40
8 is a cleaning liquid tank, 409 is an ink tank, 4
10 is a waste liquid tank, 411 is a stirring means, 412 is an ink temperature management means, and 414 is a hydrostatic tank.

At the start of cleaning, the valve 407 is opened and the valve 417 is opened.
Is closed, the three-way valve 405 is switched to the cleaning liquid tank 408 side, the three-way valves 406 and 415 are switched to the waste liquid tank 410 side, and the valve 418 is closed. At this time, the three-way valves 413 and 41
6 is still on the waste liquid tank 410 side. Then, the three-way valves 413 and 416 are switched to the side of the cleaning liquid tank 408 to circulate the cleaning liquid at such a timing that the cleaning liquid passing through the three-way valves 413 and 416 becomes clean. It is desirable to always circulate the cleaning liquid except during plate making.

When the apparatus is stopped, the valves 407 and 41 are switched almost simultaneously with the stop of the liquid sending pumps 402 and 403 from the above-mentioned washing state.
Switch 9 to closed.

(5) Non-circulating cleaning liquid type (hydrostatic pressure type / pressure feeding type during cleaning) FIG. 5 shows a fifth embodiment of the present invention. This is an example of a circulation type. 5, reference numeral 501 denotes a head, 502 denotes a feed side, 503 denotes a liquid feed pump on a return side, 504 denotes an ink density control unit, 505, 506, 514, 515, 517.
Is a three-way valve, three-way valve 505 is for switching ink / cleaning liquid on the sending side, three-way valve 506 is for switching between ink tank 509 on the return side / waste liquid tank 510 side, and three-way valves 514 and 515 are hydrostatic pressure tanks for cleaning. The three-way valve 517 is for switching between the overflow liquid ink tank 509 side and the waste liquid tank 510 side. 507, 518, 519, and 520 are valves. 508 is a cleaning liquid tank, 509 is an ink tank, 510 is a waste liquid tank, 511 is a stirring means,
512 is an ink temperature management means, 513 is a tray, 516
Is a hydrostatic tank.

According to this embodiment, at the time of cleaning, the three-way valves 514 and 515 are switched, the head cleaning liquid is directly supplied to the head 501 by bypassing the hydrostatic pressure tank 516, and cleaning of the head 501 is effectively performed quickly. Is what you do. That is, in the cleaning pattern, the valve 507 is opened and the valve 518 is closed during cleaning. The three-way valve 505 is set on the cleaning liquid tank 508 side. The three-way valves 506 and 517 are set on the waste liquid tank 510 side. After switching the valve 519 to the closed state, the cleaning liquid flows to the waste liquid tank 510 side, and the ink flow path (the three-way valve 50
5-head 501, head 501-three-way valve 50
6) and the ejection part (electrode) of the head 501 is cleaned. The cleaning of the head 501 is performed by discharging the cleaning liquid from the head 501 to the tray 513. These cleaning liquids are discharged to a waste liquid tank 510. (At this time, the valve 520 is always open.) At this time, the flow rates of the liquid sending pumps 502 and 503 are determined.
Increase the flow rate. Thereby, the cleaning effect can be improved. In addition, by increasing only the discharge amount of the liquid sending pump 202, the cleaning liquid leaks from the head discharge unit 501, so that more effective cleaning can be performed from the head discharge unit. The leaked cleaning liquid is discharged to the waste liquid tank 510 via the tray 513. This is more effectively performed at the start of cleaning and at the end of cleaning.

When the apparatus is stopped, the liquid supply pumps 502 and 503 are stopped from the above-mentioned washing state, and the valves 507 and 52 are almost simultaneously.
Switch 0 to closed.

(6) Cleaning Fluid Circulation Type (Hydrostatic Pressure Circulation System / Pressure Feeding Type During Cleaning) FIG. 6 shows a sixth embodiment of the present invention, in which a cleaning liquid performing hydrostatic pressure feeding and pressure feeding during cleaning is used. This is an example of a circulation type. 6, reference numeral 601 denotes a head, 602 denotes a feed side, 603 denotes a liquid feed pump on a return side, 604 denotes an ink density control unit, 605, 606, 614, 615, and 61.
Reference numerals 6, 618, and 619 denote three-way valves. A three-way valve 605 is for switching the ink / cleaning liquid on the feed side. A three-way valve 606 is for switching between the ink tank 609 on the return side / waste liquid tank 610. A three-way valve 614 is a cleaning liquid. Is switched between the cleaning liquid tank 608 side and the waste liquid tank 610 side. The three-way valves 615 and 616 are for bypass switching for bypassing the hydrostatic pressure tank 617 at the time of cleaning, and the three-way valves 618 and 619 are for switching between the overflow liquid ink tank 609 side and the waste liquid tank 610 side. Reference numerals 607, 620, 621, and 622 denote valves. 608, a cleaning liquid tank; 609, an ink tank; 610, a waste liquid tank;
Denotes an ink temperature management unit, 613 denotes a tray, and 617 denotes a hydrostatic pressure tank.

According to this embodiment, at the time of cleaning, the three-way valves 615 and 616 are switched to bypass the hydrostatic pressure tank 617 and to feed the head cleaning liquid, thereby effectively cleaning the head. In the cleaning pattern, the valve 607 is opened and the valve 620 is closed during cleaning. The three-way valve 605 is set on the cleaning liquid tank 608 side. The three-way valves 606 and 618 are set on the waste liquid tank 610 side. After switching the valve 621 to the closed state, the cleaning liquid flows to the waste liquid tank 610 side, and the ink flow path (between the three-way valve 605 and the head 601 and between the head 601 and the three-way valve 606)
And the ejection portion (electrode) of the head 601 is cleaned. The cleaning of the head 501 is performed by discharging the cleaning liquid from the head 601 to the tray 613. These cleaning liquids are discharged to a waste liquid tank 610. (At this time, the valve 622 is always open.) At this time, the three-way valves 614 and 619 are still in the waste liquid tank 610.
Is on the side. Then, the three-way valves 614 and 619 are removed from the cleaning liquid tank 60 at such a timing that the cleaning liquid passing through the three-way valves 614 and 619 becomes clean.
Switch to the side 8 and circulate the cleaning liquid. It is desirable to always circulate the cleaning liquid except during plate making. At this time, if the flow rates and flow rates of the liquid sending pumps 602 and 603 are increased, the cleaning effect can be improved. In addition, by increasing only the discharge amount of the liquid sending pump 602, the cleaning liquid leaks from the head discharge unit 601 and effective cleaning can be performed from the head discharge unit.
The leaked cleaning liquid is discharged to the waste liquid tank 610 via the tray 613. This is more effectively performed at the start of cleaning and at the end of cleaning.

When the apparatus is stopped, the valves 607 and 62 are switched almost simultaneously with the stop of the liquid sending pumps 602 and 603 from the above-mentioned washing state.
Switch 2 to closed.

As described above, by switching to the cleaning liquid at the time of cleaning the ink flow path in the ink-jet type ink circulation system in which the oil-based ink is ejected by utilizing the electrostatic field, the deposits in these electrodes and the circulation system flow path can be removed. Since it can be removed, it is indispensable to secure the performance of the electrostatic ink jet system.

Next, the plate material (printing plate) used in the present invention will be described. Examples of the printing original plate include a metal plate such as an aluminum plate or a chrome-plated steel plate. In particular, an aluminum plate having excellent surface water retention and abrasion resistance by graining and anodizing is preferable. As an inexpensive plate material, a plate material provided with an image receiving layer on a water-resistant support such as water-resistant paper, plastic film, or paper laminated with plastic can be used. The thickness of the plate material is suitably in the range of 100 to 300 μm, and the thickness of the image receiving layer provided is suitably in the range of 5 to 30 μm.

As the image receiving layer, a hydrophilic layer comprising an inorganic pigment and a binder, or a layer which can be made hydrophilic by a desensitizing treatment can be used.

As the inorganic pigment used in the hydrophilic image receiving layer, clay, silica, calcium carbonate, zinc oxide, aluminum oxide, barium sulfate and the like can be used. Further, as a binder, polyvinyl alcohol, starch,
Hydrophilic binders such as carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, polyacrylate, polyvinylpyrrolidone, and polymethylether-maleic anhydride copolymer can be used. If necessary, a melamine formalin resin, a urea formalin resin, or another crosslinking agent for imparting water resistance may be added.

On the other hand, examples of the image receiving layer used after the desensitization treatment include a layer using zinc oxide and a hydrophobic binder.

Zinc oxide to be used in the present invention may be, for example, zinc oxide, zinc oxide, zinc oxide, or zinc oxide, as described in “Pigment Handbook” edited by Japan Pigment Technical Association, page 319, Seibundo Co., Ltd. (1968) Any of those commercially available as wet zinc white or activated zinc white may be used. That is, zinc oxide includes, as dry methods, French methods (indirect methods), American methods (direct methods), and wet methods, depending on the starting materials and production methods. For example, Shodo Chemical Co., Ltd., Sakai Chemical Co., Ltd. ), Hakusui Chemical Co., Ltd., Honjo Chemical Co., Ltd., Toho Zinc Co., Ltd., Mitsui Kinzoku Kogyo Co., Ltd., and the like.

Examples of the resin used as a binder include styrene copolymers, methacrylate copolymers, and the like.
Examples include an acrylate copolymer, a vinyl acetate copolymer, polyvinyl butyral, an alkyd resin, an epoxy resin, an epoxy ester resin, a polyester resin, and a polyurethane resin. These resins may be used alone or 2
More than one species may be used in combination. The content of the resin in the image receiving layer is represented by a weight ratio of resin / zinc oxide, 9/91 to 2/9.
It is preferably 0/80.

Desensitization of zinc oxide is carried out by a conventional method using a desensitizing solution. Conventionally, as this type of desensitizing solution, a cyanide compound containing a ferrocyan salt or a ferricyan salt as a main component has been used. Containing treatment solution, ammine cobalt complex,
Phytic acid and its derivatives, a cyanide-free treatment liquid containing a guanidine derivative as a main component, a treatment liquid containing an inorganic acid or an organic acid that forms a chelate with zinc ions as a main component,
Alternatively, a treatment liquid containing a water-soluble polymer is known. For example, as a cyanide-containing treatment solution, JP-B-44-9045 and JP-B-46-39403;
-76101, 57-107889, 54-1
No. 17,201, and the like.

The surface of the plate material opposite to the image receiving layer is
The Beck smoothness is preferably in the range of 150 to 700 (sec / 10 cc). As a result, the formed printing plate does not shift or slip on the plate cylinder even during printing,
Good printing is performed.

Here, the Beck smoothness can be measured by a Beck smoothness tester. A Beck smoothness tester is a tester that applies a test piece to a highly smooth finished circular glass plate having a hole in the center at a constant pressure (1 kgf / cm ² (9.8 N).
/ Cm ² )) to measure the time required for a fixed amount (10 cc) of air to pass between the glass surface and the test piece under reduced pressure.

The oil-based ink used in the present invention will be described below. The oil-based ink used in the present invention is obtained by dispersing solid and hydrophobic resin particles at least at room temperature in a non-aqueous solvent having a specific electric resistance of 10 ⁹ Ωcm or more and a dielectric constant of 3.5 or less.

The specific electric resistance used in the present invention is 10 ⁹ Ωcm.
As the nonaqueous solvent having a dielectric constant of 3.5 or less, preferably a linear or branched aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon, and a halogen-substituted product of these hydrocarbons are used. is there. For example, hexane, heptane,
Octane, isooctane, decane, isodecane, decalin, nonane, dodecane, indodecane, cyclohexane, cyclooctane, cyclodecane, benzene, toluene, xylene, mesitylene, isoper C, isoper E, isoper G, isoper H, isoper L (isoper: exon , Shelsol 70, Shelsol 71 (Shelsol: trade name of Shell Oil), Amsco OMS, Amsco 460 solvent (Amsco: trade name of Spirits), silicone oil, etc., alone or in combination. Used. The upper limit of the specific electric resistance of such a non-aqueous solvent is about 10 ¹⁶ Ωcm, and the lower limit of the dielectric constant is about 1.9.

The reason why the electric resistance of the non-aqueous solvent used is in the above range is that when the electric resistance is low, the concentration of the resin particles and the like hardly occurs, and sufficient printing durability cannot be obtained. The reason for setting the above range is that when the dielectric constant is increased, the electric field is relaxed by the polarization of the solvent, whereby the ejection of the ink tends to be deteriorated.

The resin particles dispersed in the non-aqueous solvent may be any hydrophobic resin particles which are solid at a temperature of 35 ° C. or lower and have a good affinity for the non-aqueous solvent. Glass transition point is -5 ° C to 110 ° C or softening point 33 ° C
The resin (P) having a glass transition point of 10 to 100 ° C or a softening point of 38 to 1 ° C is more preferable.
20 ° C., more preferably 15 ° C.
80 ° C or a softening point of 38 ° C to 100 ° C.

By using a resin having such a glass transition point or softening point, the affinity between the surface of the image receiving layer of the printing original plate and the resin particles is increased, and the bonding between the resin particles on the printing original plate is increased. Therefore, the adhesion between the image portion and the image receiving layer is improved, and the printing durability is improved. On the other hand, regardless of whether the glass transition point or the softening point is low or high, the affinity between the image receiving surface and the resin particles is reduced, and the bonding between the resin particles is weakened.

The weight average molecular weight Mw of the resin (P) is 1 ×
10 ³ to 1 × 10 ⁶ , preferably 5 × 10 ³ to 8
× 10 ⁵ , more preferably 1 × 10 ^{4 to} 5 × 10 ⁵ .

Specific examples of such a resin (P) include:
Olefin polymers and copolymers (e.g., polyethylene, polypropylene, polyisobutylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer,
Ethylene-methacrylate copolymer, ethylene-methacrylic acid copolymer, etc.), vinyl chloride polymer and copolymer (eg, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, etc.), vinylidene chloride copolymer, alkane Vinyl acid polymers and copolymers, allyl alkanoate polymers and copolymers, polymers and copolymers of styrene and its derivatives (eg, butadiene-styrene copolymer, isoprene-styrene copolymer, styrene-methacrylate copolymer) Polymer, styrene-acrylate copolymer, etc.), acrylonitrile copolymer, methacrylonitrile copolymer, alkyl vinyl ether copolymer, acrylate polymer and copolymer, methacrylate polymer and copolymer, Itaconic acid diester polymer and copolymer, maleic anhydride Phosphate copolymers, acrylamide copolymers, methacrylamide copolymers, Funinoru resin,
Alkyd resin, polycarbonate resin, ketone resin, polyester resin, silicone resin, amide resin, hydroxyl and carboxyl group-modified polyester resin, butyral resin, polyvinyl acetal resin, urethane resin, rosin resin, hydrogenated rosin resin, petroleum resin, hydrogenated Petroleum resin, maleic acid resin, terpene resin, hydrogenated terpene resin, cumarone-indene resin, cyclized rubber-methacrylate copolymer, cyclized rubber-acrylate copolymer, heterocycle containing no nitrogen atom Included copolymers (for example, as a heterocycle, a furan ring, a tetrahydrofuran ring, a thiophene ring, a dioxane ring, a dioxofuran ring, a lactone ring, a benzofuran ring, a benzothiophene ring, a 1,3-dioxetane ring, etc.), an epoxy resin and the like. Can be

The content of the dispersed resin particles in the oil-based ink of the present invention is preferably 0.5 to 20% by weight of the whole ink. If the content is low, it becomes difficult to obtain an affinity between the ink and the surface of the printing original plate, so that a good image cannot be obtained, or problems such as reduced printing durability are likely to occur. When the number of inks increases, it is difficult to obtain a uniform dispersion liquid, and the ink flow in the discharge head tends to be uneven, so that it is difficult to obtain stable ink discharge.

The oil-based ink used in the present invention preferably contains a coloring material as a coloring component together with the above-described dispersed resin particles, for example, for plate inspection of a plate after plate making.
As the coloring material, any pigments and dyes conventionally used in oil-based ink compositions or liquid developers for electrostatography can be used.

Regarding pigments, those generally used in the technical field of printing can be used irrespective of inorganic pigments and organic pigments. Specifically, for example, carbon black, cadmium red, molybdenum red, Chrome yellow, cadmium yellow, titanium yellow, chromium oxide, viridian, cobalt green, ultramarine blue, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, sulene Conventionally known pigments such as pigments, perylene pigments, perinone pigments, thioindigo pigments, quinophthalone pigments, and metal complex pigments can be used without particular limitation.

As the dyes, azo dyes, metal complex dyes,
Naphthol dye, anthraquinone dye, indigo dye,
Oil-soluble dyes such as carbonium dyes, quinone imine dyes, xanthene dyes, aniline dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, phthalocyanine dyes and metal phthalocyanine dyes are preferred. These pigments and dyes may be used alone or in an appropriate combination, but are desirably contained in the range of 0.01 to 5% by weight based on the whole ink.

These coloring materials may be dispersed in a non-aqueous solvent as the dispersed particles themselves or separately from the dispersed resin particles, or may be contained in the dispersed resin particles. In the case of containing, pigments and the like are generally coated with the resin material of the dispersed resin particles to obtain resin-coated particles. General.

The resin particles dispersed in the non-aqueous solvent of the present invention, and further including the colored particles, preferably have an average particle size of 0.05 μm to 5 μm. More preferably, it is 0.1 μm to 1.0 μm. This particle size is CAPA-
500 (trade name, manufactured by Horiba, Ltd.).

The non-aqueous dispersion resin particles used in the present invention can be produced by a conventionally known mechanical pulverization method or polymerization granulation method. As the mechanical grinding method,
If necessary, a material as resin particles is mixed, melted and kneaded, and then directly pulverized by a conventionally known pulverizer to obtain fine particles, a dispersing polymer is used in combination, and a wet disperser (for example, a ball mill, paint shaker) , Keddy mill, Dyno mill, etc.)
A method is known in which a dispersion-assisting polymer (or a coating polymer) is kneaded in advance to form a kneaded product, then pulverized, and then dispersed in the presence of a dispersing polymer. Specifically, a method for producing a paint or a liquid developer for electrostatography can be used. For example, these methods are described in Kenji Ueki, “Flow and paint dispersion of paint”, Kyoritsu Shuppan (1971), Solomon “ Paint Science "Hirokawa Shoten (1969), Yuji Harasaki" Coating Engineering "Asakura Shoten (1971), Yuji Harasaki" Basic Science of Coatings "Maki Shoten (1977) and other books.

Examples of the polymerization granulation method include a conventionally known non-aqueous dispersion polymerization method. Specifically, Chapter 2 of Soichi Muroi, “Latest Technology of Ultrafine Polymer,” CMC Publishing (1991) ), Koichi Nakamura, "Recent Electrophotographic Development System and Development and Practical Use of Toner Materials", Chapter 3, (Nippon Kagaku Kagaku Co., Ltd. 1985), KEJ Barrett, "Dispersi
on Polymerization Organic Media "John Wiley (19
75)).

Usually, a dispersion polymer is used in combination to stabilize the dispersion of the dispersed particles in a non-aqueous solvent. The dispersed polymer contains a repeating unit soluble in a non-aqueous solvent as a main component, and has an average molecular weight of 1 × 10 in weight average molecular weight Mw.
^It is preferably ³ to 1 × 10 ⁶ , more preferably 5 × 10 ³
５5 × 10 ⁵ .

As preferred soluble repeating units of the dispersion polymer used in the present invention, there may be mentioned a polymerization component represented by the following general formula (I).

[0104]

Embedded image

In the general formula (I), X ₁ is —COO
Represents-, -OCO- or -O-. R represents 10 carbon atoms
Represents an alkyl group or alkenyl group having from 32 to 32, preferably represents an alkyl group or an alkenyl group having from 10 to 22 carbon atoms, and may be linear or branched, and is preferably unsubstituted. It may be. Specifically, decyl group, dodecyl group, tridecyl group, tetradecyl group, hexadecyl group, octadecyl group, eicosanyl group, docosanyl group, decenyl group, dodecenyl group, tridecenyl group, hexadecenyl group, octadecenyl group, linolenyl group, and the like. .

A₁And a_TwoAre the same or different
Hydrogen atom, halogen atom (for example, chlorine
Atom, bromine atom, etc.), cyano group, alkyl having 1 to 3 carbon atoms
(For example, methyl group, ethyl group, propyl group, etc.),
-COO-Z₁Or -CH _TwoCOO-Z₁[Z₁Is
An optionally substituted hydrocarbon group having 22 or less carbon atoms (eg,
For example, alkyl group, alkenyl group, aralkyl group, alicyclic
A formula group, an aryl group, etc.).

Among the hydrocarbon groups represented by Z ₁ , preferred hydrocarbon groups are alkyl groups having 1 to 22 carbon atoms which may be substituted (for example, methyl group, ethyl group, propyl group, butyl group, Hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tridecyl,
Tetradecyl group, hexadecyl group, octadecyl group, eicosanyl group, docosanyl group, 2-chloroethyl group,
A bromoethyl group, a 2-cyanoethyl group, a 2-methoxycarbonylethyl group, a 2-methoxyethyl group, a 3-bromopropyl group, etc., and an optionally substituted alkenyl group having 4 to 18 carbon atoms (for example, 2-methyl- 1-propenyl group, 2-butenyl group, 2-pentenyl group, 3-methyl-
2-pentenyl group, 1-pentenyl group, 1-hexenyl group, 2-hexenyl group, 4-methyl-2-hexenyl group, decenyl group, dodecenyl group, tridecenyl group, hexadecenyl group, octadecenyl group, linolenyl group, etc.),
An aralkyl group having 7 to 12 carbon atoms which may be substituted (for example, benzyl group, phenethyl group, 3-phenylpropyl group, naphthylmethyl group, 2-naphthylethyl group, chlorobenzyl group, bromobenzyl group, methylbenzyl group, An ethylbenzyl group, a methoxybenzyl group, a dimethylbenzyl group, a dimethoxybenzyl group, etc., an alicyclic group having 5 to 8 carbon atoms which may be substituted (for example, cyclohexyl group,
-Cyclohexylethyl group, 2-cyclopentylethyl group, etc.) and an optionally substituted aromatic group having 6 to 12 carbon atoms (for example, phenyl group, naphthyl group, tolyl group, xylyl group, propylphenyl group, butylphenyl group) , Octylphenyl, dodecylphenyl, methoxyphenyl, ethoxyphenyl, butoxyphenyl, decyloxyphenyl, chlorophenyl, dichlorophenyl, bromophenyl, cyanophenyl, acetylphenyl, methoxycarbonylphenyl, ethoxy Carbonylphenyl group, butoxycarbonylphenyl group, acetamidophenyl group, propionamidophenyl group, dodecyloylamidophenyl group, etc.).

In the dispersion polymer, another repeating unit may be contained as a copolymer component together with the repeating unit represented by the general formula (I). Other copolymer components include:
Any compound may be used as long as it is composed of a monomer copolymerizable with a monomer corresponding to the repeating unit of the general formula (I).

The proportion of the polymer component represented by the general formula (I) in the dispersion polymer is preferably at least 50% by weight, more preferably at least 60% by weight. Specific examples of these dispersion polymers are described in JP-A-10-20
No. 4354, No. 10-204356, No. 10-259
No. 336, No. 10-306244, No. 10-3169
No. 17, No. 10-316920, and the dispersion stabilizing resin (Q-1) used in Examples, and a commercially available product (Solprene 1205, manufactured by Asahi Kasei Corporation). It can also be used.

When the resin (P) particles are produced as a dispersion (latex) or the like, the dispersion polymer is preferably added in advance during the polymerization. When the dispersing polymer is used, the addition amount is 1 to 50 based on the resin for particles (P).
% By weight.

The dispersed resin particles and colored particles (or coloring material particles) in the oil-based ink of the present invention are preferably positively or negatively charged electro-detectable particles. In order to impart an electric detecting property to these particles, it can be achieved by appropriately utilizing a technique of a wet type electrophotographic developer. Specifically, the above-mentioned "Recent development and practical use of electrophotographic development systems and toner materials", pages 139 to 148, "Basics and Application of Electrophotographic Technology", edited by the Society of Electrophotography, 497-505 (Corona Co., 1988)
Annual), Yuji Harasaki "Electrophotography" 16 (No. 2), 44
The method is performed by using an electric detection material such as a charge control agent described on page (1977) and other additives.

More specifically, for example, British Patent No. 8934
No. 29, No. 934038, No. 11222397,
U.S. Pat. No. 3,900,412, equivalent 4,606,899,
JP-A-60-179751, JP-A-60-185963
And JP-A-2-13965.
The charge control agent as described above is used as the carrier liquid dispersion medium 10.
0.001 to 1.0 part by weight based on 00 parts by weight is preferred. If desired, various additives may be added. The upper limit of the total amount of these additives is regulated by the electric resistance of the oil-based ink. That is, if the specific electrical resistance of the ink from which the dispersed particles have been removed is lower than 10 ⁹ Ωcm, it becomes difficult to obtain a high-quality continuous tone image. desirable.

[0113]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples. First, a production example of the ink resin particles (PL) will be described.

Production Example 1 of Resin Particles (PL-1) A mixed solution of 10 g of dispersion stabilizing resin (Q-1) having the following structure, 100 g of vinyl acetate and 384 g of Isopar H was heated to a temperature of 70 ° C. while stirring under a nitrogen stream. did. 2,2'-azobis (isovaleronitrile) as a polymerization initiator
0.8 g (abbreviation AIVN) was added and reacted for 3 hours. Twenty minutes after the initiator was added, cloudiness occurred and the reaction temperature rose to 88 ° C. Furthermore, 0.5 g of this initiator was added, and after reacting for 2 hours, the temperature was raised to 100 ° C., and the mixture was stirred for 2 hours to distill off unreacted vinyl acetate. After cooling, the mixture was passed through a 200-mesh nylon cloth, and the resulting white dispersion was a latex having a degree of polymerization of 90% and an average particle diameter of 0.23 μm and having good monodispersity. The particle size was measured with CAPA-500 (manufactured by Horiba, Ltd.).

[0115]

Embedded image

A part of the white dispersion was centrifuged (1 × 10 ⁴ rpm, rotation time: 60 minutes), and the precipitated resin particles were collected and dried. Weight average molecular weight of resin particles (Mw: GPC in terms of polystyrene)
Value) was 2 × 10 ⁵ , and the glass transition point (Tg) was 38 ° C.

Example 1 First, an oil-based ink was prepared. <Preparation of oil-based ink (IK-1)> 10 g of dodecyl methacrylate / acrylic acid copolymer (copolymerization ratio; 95/5 weight ratio), 10 g of nigrosine and Shellsol 7
1 g together with glass beads was placed in a paint shaker (manufactured by Toyo Seiki Co., Ltd.) and dispersed for 4 hours to obtain a fine dispersion of nigrosine. Production example 1 of resin particles for ink
60 g (as solid content) of the resin particles (PL-1) produced in the above, 2.5 g of the above nigrosine dispersion, FOC-14
00 (Nissan Chemical Co., Ltd., tetradecyl alcohol) 1
A black oil-based ink was prepared by diluting 5 g, and 0.08 g of octadecene-half-maleic acid octadecylamide copolymer into 1 liter of Isopar G.

Next, 2 liters of the oil-based ink (IK-1) prepared as described above was filled in the ink tank of the ink jet drawing apparatus 2 of the plate making apparatus (see FIGS. 7 and 9). Here, the ejection head is 900 dp shown in FIG.
i, a 64 channel multi-channel head was used. A throwing heater and a stirring blade were provided in the ink tank as ink temperature management means, the ink temperature was set at 30 ° C., and the temperature was controlled with a thermostat while rotating the stirring blade at 30 rpm. Here, the stirring blade was also used as a stirring means for preventing sedimentation and aggregation. Further, the ink flow path is partially transparent, and an LED light emitting element and a light detecting element are arranged with the ink flow path interposed therebetween.
The solid content concentration of 1) was adjusted twice)) and the concentration was controlled by feeding. Prior to plate making, plate making was performed by removing the cleaning liquid at the start of plate making from the ink circulation system filled with the cleaning liquid by the pump pressure circulation system according to the first embodiment of the present invention as shown in FIG. .

As a plate material, a 0.12 mm-thick aluminum plate subjected to graining and anodizing treatment was mounted with a plate head and a plate edge added by a mechanical device provided on a drum of a plate making device. After removing dust from the surface of the plate by suction with an air pump, move the discharge head close to the plate until the drawing position,
The image data to be made was transmitted to the image data calculation control unit, and the 64-channel ejection head was moved while rotating the drum, thereby ejecting oily ink onto the aluminum plate to form an image. At this time, the tip width of the ejection electrode of the ink jet head was set to 10 μm, and the distance between the head and the plate material was controlled to be 1 mm based on the output from the optical gap detector. A voltage of 2.5 KV is constantly applied as a bias voltage, and when performing ejection, a pulse voltage of 500 V is further superimposed, and the pulse voltage is 256 steps within a range of 0.2 ms to 0.05 ms. The drawing was performed while changing the area of the dot by changing.
No drawing failure due to greeting was observed at all, and no image deterioration due to a change in the dot diameter was observed even when the outside air temperature changed or the number of plate making increased, and good plate making was possible.

Further, the image was strengthened by heating with a xenon flash fixing device (light emission intensity 200 J / pulse, manufactured by Ushio Inc.) to produce a printing plate. In order to protect the ink jet head, the ink jet drawing apparatus is retracted by 50 mm from the position adjacent to the drum together with the sub-scanning means.
It was mounted on a plate cylinder of a 66EPZ printing machine and printing was performed.

The obtained printed matter was an extremely clear image without any skipping or blurring in the printed image even after 10,000 sheets were passed. After completion of plate making, as shown in FIG. 1 again, ink is removed from the ink circulation system by a pump pressure circulation system and filled with a cleaning liquid, and further, Isopar G is supplied to the head for 10 minutes. After cleaning by dripping Isopar G from the head opening and storing the head in a cover filled with vapor of Isopar G, good printed matter can be obtained without maintenance work for 6 months. The printing plate to be given could be made.

Example 2 A device of the type shown in FIG.
A full line inkjet head was arranged. A pump is used for ink circulation.Ink reservoirs are respectively provided between the pump and the ink inflow path of the ejection head, and between the ink recovery path of the ejection head and the ink tank, and ink circulation is performed by a difference in hydrostatic pressure between the ink tanks. A heater and the above-mentioned pump were used as temperature control means, the ink temperature was set to 35 ° C., and the temperature was controlled by a thermostat. Here, the circulation pump was also used as a stirring means for preventing precipitation and aggregation. In addition, a conductivity measuring device was arranged in the ink flow path, and density control was performed by diluting the ink or feeding the concentrated ink based on the output signal. The above-described aluminum plate was similarly mounted on a drum of a plate-making apparatus as a plate material. After removing dust from the surface of the plate using a rotating brush made of nylon, the image data to be made is transmitted to the image data calculation control unit, and the plate material is drawn by a full line head while transporting the plate using a capstan roller. An image was formed by discharging oil-based ink onto the aluminum plate. Prior to plate making, plate making was performed by removing the cleaning liquid at the start of plate making from the ink circulation system filled with the cleaning liquid according to the third embodiment of the present invention as shown in FIG. No drawing failures due to dust were observed at all, and no image deterioration due to changes in dot diameter was observed even due to changes in outside air temperature and increase in the number of plate making.
Good plate making was possible. Heat roller (30
0W halogen lamp included Teflon (registered trademark) silicone rubber roller) Heated by fixing (pressure: 3 kg
f / cm ² (29.4 N / cm ² )) The image was strengthened and a printing plate was prepared.

Further, when printing was performed on the prepressed plate in the same manner as in Example 1, the printed image was extremely clear without any skipping or blurring even after 10,000 sheets were passed. After completion of plate making, the ink is removed from the ink circulation system again as shown in FIG. 3 to fill with a cleaning liquid. Further, the head is circulated, and then the nonwoven fabric containing the isoper G is removed. When the cleaning was carried out by contacting the tip, a printing plate giving good printed matter could be produced for 6 months without maintenance work. Further, instead of the ink jet head of the type shown in FIG.
When a similar operation was performed using a 600 dpi full line inkjet head of the type shown in FIGS. 14 and 16,
In each case, good results were obtained as described above.

Example 3 The cleaning liquid was circulated through the ink circulation system according to the fourth embodiment of the present invention as shown in FIG. 4 before plate making, but these cleaning liquids were supplied to the cleaning liquid tank at the start of plate making. After the collection, the ink was sent to an ink circulation system to perform plate making. Further, instead of the aluminum plate of Example 1, a plate material provided with an image receiving layer capable of being made hydrophilic by a desensitizing treatment was used on the surface described below, and a plate surface desensitizing treatment device was used after the printing plate was prepared. Example 1 except that the non-image area was hydrophilized using the above method, the plate material conductive layer was grounded by contact with a conductive leaf spring (made of phosphor bronze) at the time of drawing, and fixing was performed by applying hot air to the plate material. The same operation was performed.

A high-quality paper having a basis weight of 100 g / m ² was used as a substrate. The layer coating is applied on one side, and after drying, the applied amount is 10 g / m ² .
Further, the dispersion A was dried thereon and dried at a coating amount of 15 g /
An image receiving layer was provided so as to obtain a plate material of m ² .

Coating for conductive layer; carbon black (30
% Aqueous dispersion), 5.4 parts, clay (50% aqueous dispersion) 5
4.6 parts, SBR latex (solid content 50%, Tg25
C) 36 parts and melamine resin (solid content 80%, Sumiretz Resin SR-613) 4 parts were mixed, and the total solid content was 2
Water was added so as to be 5% to obtain a paint.

Dispersion A: 100 g of dry zinc oxide, 3 g of binder resin (B-1) having the following structure, and binder resin (B-2) 1
A mixture of 7 g, 0.15 g of benzoic acid and 155 g of toluene was wet-dispersed with a homogenizer (manufactured by Nippon Seiki Co., Ltd.).
For 8 minutes at 6,000 rpm.

[0128]

Embedded image

When fixing was performed by blowing hot air on the plate material, blisters were generated. Therefore, the fixing was performed by gradually increasing the supply power to the heater used for the hot air, or by gradually decreasing the rotation speed of the drum from high speed to low speed without changing the supply power.
As a result, no blister was generated, and the printed matter obtained by printing the printing plate was an extremely clear image without any skipping or blurring in the printed image even when the number of sheets passed 5,000.

[0130]

According to the present invention, it is possible to prepare a printing plate capable of printing a large number of prints of clear images. In addition, a printing plate directly corresponding to digital image data can be stably formed with high image quality, and inexpensive and high-speed lithographic printing can be performed. Moreover, since the deposits in the ejection electrode and the ink circulation system flow path can be effectively removed, stable ejection performance can be obtained for a long period of time.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, which is an example of a cleaning liquid non-circulation type using a pump pressure feeding circulation system.

FIG. 2 shows a second embodiment of the present invention, and is an example of a cleaning liquid circulation type using a pump pressure circulation system.

FIG. 3 shows a third embodiment of the present invention and is an example of a non-circulating type of cleaning liquid using a hydrostatic circulation system.

FIG. 4 shows a fourth embodiment of the present invention, which is an example of a cleaning liquid circulation type using a hydrostatic circulation system.

FIG. 5 shows a fifth embodiment of the present invention, and is an example of a cleaning liquid non-circulation type using a hydrostatic pressure type and a cleaning-time pressure feeding system.

FIG. 6 shows a sixth embodiment of the present invention, and is an example of a cleaning liquid circulation type using a hydrostatic pressure type and a pressure feed system during cleaning.

FIG. 7 is an overall configuration diagram schematically illustrating an example of a plate making apparatus used in the present invention.

FIG. 8 is an overall configuration diagram schematically showing another example of the plate making apparatus used in the present invention.

FIG. 9 is a configuration diagram schematically illustrating an example of a drawing unit of the plate making apparatus used in the present invention.

FIG. 10 is a schematic configuration diagram illustrating an example of an ejection head provided in an ink jet drawing apparatus used in the present invention.

FIG. 11 is a schematic cross-sectional view of the vicinity of an ink ejection unit in FIG.

FIG. 12 is a schematic cross-sectional view of an example of another ejection head provided in the inkjet drawing apparatus used in the present invention, in the vicinity of an ink ejection section.

FIG. 13 is a schematic front view of the vicinity of an ink ejection unit in FIG. 12;

FIG. 14 is a schematic configuration diagram showing a main part of an example of another ejection head provided in the ink jet drawing apparatus used in the present invention.

FIG. 15 is a schematic configuration diagram of a head obtained by removing a regulating plate from the ejection head of FIG.

FIG. 16 is a schematic configuration diagram showing a main part of an example of another ejection head provided in the ink jet drawing apparatus used in the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 plate making device 2 ink jet drawing device 5 fixing device 6 plate surface desensitizing device 7 plate material automatic plate feeding device 8 plate material automatic plate discharging device 9 plate material (printing plate) 10 dust removing means 11 drum 12 capstan roller 13 grounding means 21 Image data calculation control unit 22 Discharge head 221 Upper unit 222 Lower unit 22a Discharge slit 22b Discharge electrode 23 Oil-based ink 24 Ink supply unit 25 Ink tank 26 Ink supply device 27 Stirring unit 28 Ink temperature management unit 29 Ink density control unit 30 Encoder 31 Head separation / contact device 32 Head sub-scanning means 33 First insulating substrate 34 Second insulating substrate 35 Slope of second insulating substrate 36 Upper surface of second insulating substrate 37 Inflow of ink Road 38 Ink recovery path 39 Backing 40 Groove 41 Head book 42, 42 'Meniscus regulating plate 43 Ink groove 44 Partition wall 45, 45' Ejection part 46 Partition wall 47 Partition end part 50, 50 'Support member 51, 51' Groove 52 Partition wall 53 Upper end part 54 Rectangular part 55 Upper end of partition 56 Guide projection 101, 201, 301, 401, 501, 601 heads 102, 202, 302, 402, 502, 602,
Feed-side liquid transfer pumps 103, 203, 303, 403, 503, 603,
Feed side liquid feed pumps 104, 204, 304, 404, 504, 604 Ink density control means 105, 106, 205, 206, 214, 305, 3
06, 314, 405, 406, 413, 415, 41
6, 505, 506, 514, 515, 517, 60
5, 606, 614, 615, 616, 619 Three-way valve 107, 207, 114, 115, 215, 116, 2
16, 217, 307, 315, 316, 317, 40
7, 417, 418, 419, 507, 518, 51
9, 520, 607, 620, 621, 622 Valve 108, 208, 308, 408, 508, 608 Cleaning liquid tank 109, 209, 309, 409, 509, 609 Ink tank 110, 210, 310, 410, 510, 610 Waste liquid tank 111, 211, 311, 411, 511, 611 Stirring means 112, 212, 312, 412, 512, 612 Ink temperature management means 113, 213, 513, 613 Receiving tray 313, 414, 516, 617 Hydrostatic tank

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 EA24 FA07 FA10 FA13 FB01 JB15 KB21 KD01 2H084 AA25 AA38 AE05 BB02 BB16 CC05

Claims (20)

[Claims] 1. An image is formed directly on a plate material by an electrostatic ink jet method in which an oil-based ink is discharged using an electrostatic field based on a signal of image data, and the image is fixed to form a printing plate. An ink circulating system having the following a, b, and c: a, an inkjet discharge head, b, an ink supply system for supplying the oily ink to the inkjet discharge head, and the oily ink from the inkjet discharge head. C, an ink tank for storing the oil-based ink, a cleaning liquid feeding system for supplying a cleaning liquid to the ink feeding system, and an ink feeding system for feeding the cleaning liquid to the ink feeding system. A cleaning liquid recovery system for recovering the ink from the ink supply system during cleaning. Plate making method with, for connecting the cleaning liquid supply system and the cleaning liquid recovery system to the ink supply system, and performing by feeding a cleaning liquid to the ink supply system cleaning away. 2. The plate making method according to claim 1, wherein said cleaning liquid circulates during cleaning. 3. The method according to claim 1, wherein the flow rate of the cleaning liquid during cleaning is higher than the flow rate of ink during drawing. 4. The oil-based ink has a specific electric resistance of 10
^The solid and hydrophobic resin particles are dispersed at least at room temperature in a non-aqueous solvent having a resistivity of ⁹ Ωcm or more and a dielectric constant of 3.5 or less. Plate making method. 5. An ink jet drawing apparatus as an image forming means for forming an image directly on a plate material by discharging an oil-based ink from a discharge head using an electrostatic field based on a signal of image data, and said image forming means An image fixing means for fixing the image formed in step 1 to obtain a printing plate, wherein the image forming means comprises: an inkjet discharge head; an ink supply means for supplying the oil-based ink to the inkjet discharge head; An ink supply unit including an ink collection unit configured to collect the oil-based ink from the inkjet discharge head; an ink circulation unit including an ink tank configured to store the oil-based ink; and supplying the cleaning liquid to the ink supply unit. A cleaning liquid feeding unit that cleans the cleaning liquid from the ink feeding unit; Cleaning liquid recovery means, supply side switching means for disconnecting the ink tank from the ink liquid supply means, and connecting the cleaning liquid supply means to the ink liquid supply means, and supplying the cleaning liquid recovery means to the ink liquid supply means. And a collecting-side switching means connected to the plate-making apparatus. 6. A circulating means for circulating the cleaning liquid at the time of cleaning.
The plate making device described in the above. 7. The plate-making apparatus according to claim 5, further comprising a flow rate changing unit that makes the flow rate of the cleaning liquid at the time of cleaning faster than the flow rate of the ink at the time of drawing. 8. The ink according to claim 1, wherein the oil-based ink has a specific electric resistance of 10 ^9.
The plate-making according to any one of claims 5 to 7, wherein solid and hydrophobic resin particles are dispersed at least at room temperature in a non-aqueous solvent having a resistivity of not less than Ωcm and not more than 3.5. apparatus. 9. The plate-making method according to claim 5, wherein the image fixing means has a heating means using a heat roller and / or an infrared lamp, a halogen lamp or a xenon flash lamp. apparatus. 10. The plate-making apparatus according to claim 9, wherein the heating means is arranged and / or controlled so as to gradually increase the temperature of the plate material when fixing the image. . 11. The plate making apparatus according to claim 5, wherein a main scan is performed by rotating a drum on which the plate is mounted when drawing on the plate. 12. The plate making apparatus according to claim 11, wherein the discharge head is a single-channel head or a multi-channel head, and performs sub-scanning by moving the discharge head in the axial direction of the drum. . 13. The sub-scanning device according to claim 5, wherein at the time of drawing on the plate material, sub-scanning is performed by nipping and moving the plate material by at least a pair of capstan rollers. The plate making device described in the above. 14. The apparatus according to claim 1, wherein the ejection head comprises a single-channel head or a multi-channel head, and performs main scanning by moving the ejection head in a direction orthogonal to a traveling direction of the printing plate. 13
The plate making device described in the above. 15. The plate making apparatus according to claim 11, wherein the discharge head is a full line head having a length substantially equal to a width of the plate material. 16. The apparatus according to claim 5, further comprising dust removing means for removing dust existing on the surface of the printing plate before and / or during drawing on the printing plate. The plate making device described in the above. 17. The ink jet drawing apparatus according to claim 5, further comprising a stirring unit for stirring the oil-based ink in an ink tank storing the oil-based ink.
The plate-making apparatus according to any one of claims 16 to 16. 18. The ink-jet drawing apparatus according to claim 5, wherein said ink-jet drawing apparatus has an ink temperature managing means for managing a temperature of said oil-based ink in an ink tank storing said oil-based ink. The plate making device described in the above. 19. The plate making apparatus according to claim 5, wherein said ink jet drawing apparatus has an ink density control means for controlling the density of said oil-based ink. 20. The apparatus according to claim 5, further comprising cleaning means for cleaning said discharge head.
10. The plate making device according to any one of items 9 to 9.