JP2003072020A - Plate-making method and plate-making apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plate-making method for a plate material which can correspond to digital image data and produce numbers of prints of a clear image inexpensively at a high speed, and a plate-making apparatus. SOLUTION: In the plate-making method in which, on the basis of the signal of image data, an image is formed directly on the plate material by an electrostatic ink-jet method for discharging oil ink from a discharge head by using an electrostatic field, and the image is fixed to manufacture a machine plate, before the image is formed on the plate material and/or during the image being formed, an adhesive roller 10 is rotated on the plate material 9 to attract/ remove dust on the plate material 9.

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 to a plate-making method and a plate-making apparatus having good plate-making image quality and print image quality using oil-based ink.

[0002]

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

To record an image on a printing original plate (plate making), an image original is once output to a silver salt photographic film in an analog or digital manner, and a diazo resin or a photopolymerizable photopolymer photosensitive material (printing original plate) is passed through this. It is a general method to expose the non-image area and to elute and remove the non-image area mainly using an alkaline solution.

In recent years, in the planographic printing method, due to recent demands for improvement of digital drawing technology and process efficiency,
Many systems for directly drawing digital image information on a printing original plate have been proposed. This is a CTP (Computer
-to-plate) or DDPP (Digital Direct Pri
This is a technology called "nting plate". As a plate-making method, for example, there is a system for recording an image in an optical mode or a thermal mode by using a laser, and a part of the system has been put into practical use.

However, in this plate-making method, in both the optical mode and the heat mode, generally, after laser recording, the plate-making is carried out by treating with an alkaline developing solution to dissolve and remove the non-image area,
Alkaline waste liquid is discharged, which is not preferable for environmental protection.

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

Japanese Unexamined Patent Publication (Kokai) No. 64-27953 discloses a method of making a plate by drawing an image on a hydrophilic plate material using a lipophilic wax ink with an ink jet. In this method, since the image is formed of wax, the mechanical strength of the image area is weak and the adhesion to the hydrophilic surface of the plate material is insufficient, so that the printing durability is low.

Further, in order to obtain a high quality image, it is necessary to keep the ejection state of the ink jet good. That is, as the head is used, the ink component adheres to the head, and it is necessary to remove the adhered component. Conventionally, the cleaning of the head has been performed when a predetermined use time has passed or when the image quality has deteriorated, so that the head is often used in a dirty state. Also, depending on the ink component, the ink component may stick to the surface, and it is often difficult to remove it with ordinary cleaning means. In this case, since it is not possible to sufficiently remove the dirt on the head, it is necessary to repeat the cleaning frequently, and dirt that cannot be completely removed is accumulated, resulting in accelerating the deterioration of the head.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a digital plate-making method and a plate-making apparatus which do not require a developing process, and are inexpensive and simple. It is an object of the present invention to provide a plate making method and a plate making apparatus capable of forming a high quality image on a plate material by removing dust on the plate material.

[0010]

In order to achieve the above object, a plate making method according to a first aspect of the present invention uses an electrostatic field to discharge an oil-based ink from an ejection head based on a signal of image data. A method of making a plate by directly forming an image on a plate material by an ink jet system and fixing the image to form a printing plate, wherein the pressure-sensitive adhesive is applied before and / or during image formation on the plate material. It is characterized in that the characteristic roller is rolled on the plate material to adsorb and remove dust on the plate material.

The plate making method according to the second aspect is characterized in that the adhesive force of the adhesive roller is 4 hPa or more and 250 hPa or less.

In the plate making method, the oil-based ink has a specific electric resistance value of 10 ⁹ Ωcm or more and a dielectric constant of 3.5.
It may be characterized in that solid and hydrophobic resin particles are dispersed at least at room temperature in the following non-aqueous solvent.

According to a third aspect of the present invention, in the plate making apparatus, an image forming means for directly forming an image on the plate material and an image formed by the image forming means are fixed to obtain a printing plate based on an image data signal. An image fixing unit, and the image forming unit,
A plate making apparatus which is an ink jet drawing apparatus for ejecting oil-based ink from an ejection head by utilizing an electrostatic field, wherein an adhesive roller for adsorbing and removing dust on the plate material is provided on the upstream side in the plate material moving direction of the ink jet drawing apparatus. It is characterized in that it is arranged so as to be rollable on the plate material.

The plate making apparatus according to claim 4 is characterized in that the adhesive force of the adhesive roller is 4 hPa or more and 250 hPa or less.

According to a fifth aspect of the present invention, in the plate making apparatus, the adhesive roller is composed of two or more adhesive rollers having different adhesive forces, and one adhesive roller is rolled on the plate material.
Another adhesive roller having an adhesive force larger than that of the one adhesive roller is brought into contact with the one adhesive roller.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The present invention, on the plate material (printing original plate),
An image is formed by an inkjet method in which an 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 electric field forming conditions. Therefore, by using a small ejection electrode or adjusting an electric field forming condition, a small ink droplet can be obtained without reducing the ejection nozzle diameter or the ejection slit width. Therefore, the present invention provides a plate making method and a plate making apparatus which can control a minute image without a problem of ink clogging of a head and can obtain a printing plate capable of printing a large number of prints having clear images.

An example of the construction of the plate making apparatus used for carrying out the plate making method of the present invention is shown below. 1 and 2 are overall configuration diagrams of a plate making apparatus. Fig. 3 shows the control part of the plate making device.
4 is a schematic configuration example of a drawing unit including an ink supply unit and a head separating / contacting mechanism. Further, FIGS. 4 to 10 are for explaining an inkjet drawing apparatus included in the plate making apparatus of FIGS. 1 and 2.

First, the plate making process according to the present invention will be described with reference to the overall construction 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 aluminum, metal such as stainless steel or iron, plastic, glass or the like. Particularly in the case of a metal drum, its surface is often anodized or chrome-plated in order to enhance its wear resistance and rust resistance. The drum 11 may have a heat insulating material on its surface as described later. Further, the drum 11 preferably has a grounding function as a counter electrode of the ejection head electrode in electrostatic field ejection. On the other hand, when the substrate of the plate material has a high insulating property, 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, known means such as a brush, a leaf spring, and a roller having conductivity can be used.

Further, the plate making apparatus 1 has an ink jet drawing apparatus 2, which allows the image data calculation control section 21.
Oily ink is ejected onto the plate material 9 mounted on the drum 11 to form an image corresponding to the image data sent.

The plate making apparatus 1 also 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 necessary for the purpose of enhancing the hydrophilicity of the surface of the plate material 9 may be installed.

In the plate making apparatus 1, an adhesive roller 10 for adsorbing and removing the dust on the plate material is arranged on the upstream side of the ink jet drawing apparatus 2 in the plate material moving direction so as to be rollable on the plate material 9. I have set up. Here, rolling means that the adhesive roller 10 is in contact with the plate material 9 and moves relative to the plate material 9 while rotating (including driven rotation or rotation). In the configuration of the present embodiment, the pressure-sensitive adhesive roller 10 rotates at the fixed position with respect to the rotating plate material 9, so that the pressure-sensitive adhesive roller 10 and the plate material 9 move relatively.

The adhesive roller 10 can be brought into contact with and separated from the plate material 9 by a separation / contact mechanism (not shown). The adhesive roller 10 removes dust existing on the surface of the plate material before and / or during drawing on the plate material 9. That is, the dust on the plate material 9 may be removed only before drawing, only during drawing, or before and during drawing. Adhesive roller 10
Can be formed, for example, by applying an adhesive layer to the outer periphery of a tubular core material made of metal. As a tubular core material,
In addition to metals, ceramics and plastics are used. Examples of the adhesive layer include rubber adhesives and acrylic adhesives. Adhesive roller 10 is JI
Adhesive strength determined by the method according to the "Test for adhering two parallel metal plates with rubber" in the section "Adhesion test between metal and vulcanized rubber" of S-K6301 vulcanized rubber physical test method Four
It is preferably hPa or more and 250 hPa or less,
More preferably, it is 7 hPa or more and 180 hPa or less. As Table 1 shows the adhesive strength of the adhesive roller 10 and the result of performance evaluation, it is almost impossible to remove dust at 4 hPa or less, and the adhesive roller 10 cannot be used. 4 hP
The effect of removing dust is observed when the value is a or more, but the effect is further improved when the value is 7 hPa or more. Further, when the adhesive roller 10 having a pressure of 250 hPa or more is used, there arises a problem that stains are generated during printing and printing durability is deteriorated. 250h
When it is 180 hPa or less, it can be used, but when it is 180 hPa or less, the above-mentioned problems do not occur and the quality level at the time of printing is further improved.

[0025]

[Table 1]

The pressure-sensitive adhesive roller 10 may be composed of one pressure roller or two or more pressure-sensitive adhesive rollers having different adhesive strengths. In this embodiment, the adhesive roller 10 is set to 2
It is composed of one adhesive roller 10a, 10b. In such a configuration, one adhesive roller 10a is rolled on the plate material 9, and the other adhesive roller 10b is brought into direct or indirect contact with this one adhesive roller 10a to form one adhesive roller. Dust adhering to 10a is adsorbed and removed.

Here, “direct” means another adhesive roller 10
This is a configuration (the present embodiment) in which b is directly rolled on the adhesive roller 10a. Therefore, when there are two or more adhesive rollers 10b, a plurality of adhesive rollers 10b come into contact with the adhesive roller 10a at the same time. Indirectly, when there are two or more adhesive rollers 10b, the adhesive roller 1
This is a configuration in which 0b is brought into contact in series. Therefore, in the case of this mechanism, one adhesive roller 10b always contacts the adhesive roller 10a. Then, the adhesive force of the adhesive roller 10b is set to be larger than the adhesive force of the adhesive roller 10a. That is, the adhesive roller 10b works as a cleaning roller for the adhesive roller 10a. In addition, if there are two or more adhesive rollers 10b,
Adhesive rollers 10b (adhesive rollers 10b1, 10b2, 1
0b3, ...) In the case of a structure in which they are contacted in series, the adhesive force is 10b1 <10b2 <10b3 <.
・ ・

According to the former direct contact, a plurality of adhesive rollers 10b can adsorb and remove dust on the adhesive rollers 10a at the same time. Further, according to the latter indirect contact, the dust adhering to the adhesive roller 10a can be sequentially adsorbed and removed by the other adhesive roller 10b, and the adhesive can always be adhered by the clean adhesive roller 10b to which no dust is attached. Roller 10a
The dust can be adsorbed and removed, the ability to adsorb and remove the dust can be maintained for a long time, and reverse adhesion from the adhesive roller 10a to the plate material can be reliably prevented.

Further, even if an automatic plate feeding device 7 for automatically feeding the plate material 9 onto the drum 11 and an automatic plate discharging device 8 for automatically removing the plate material 9 after drawing is installed, Good. By using the automatic plate feeding device 7 and the automatic plate discharging device 8, the plate making operation becomes simpler and the plate making time can be shortened, so that the effect of the present invention can be further enhanced.

A plate making apparatus 1 with reference to FIG. 1 and a part of FIG.
The process of making a printing plate by means of will be described below.

First, the plate material 9 is mounted on the drum 11 using the automatic plate feeder 7. At this time, the plate material 9 is tightly fixed on the drum 11 by a mechanical method such as a known plate edge / tail gripping device, an air suction device, or an electrostatic method, whereby the plate edge flaps and is drawn. It is possible to prevent the ink-jet drawing device 2 from coming into contact with and sometimes being damaged. Further, a means for bringing the plate material 9 into close contact with the drum 11 is provided only around the drawing position of the ink jet drawing device 2, and at least when drawing is performed, this means is acted to prevent the plate material 9 from contacting the ink jet drawing device 2. You can also do it. Specifically, for example, there is a method of arranging 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, and thereby it is possible to effectively prevent the occurrence of troubles such as contact damage in the inkjet drawing device 2.

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, and also selects an appropriate pixel for the decomposed data. Number and the number of gradations. Further, the dot area ratio is also calculated in order to draw the oil-based ink image in half-tone dots using the ink-jet ejection head 22 (see FIG. 3, which will be described later in detail) of the ink-jet drawing device 2. Also, as described below,
The image data calculation control unit 21 controls the movement of the inkjet ejection head 22 and the ejection 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 the buffer. The image data calculation control unit 21 rotates the drum 11 and causes the ejection head 22 to rotate.
Is brought close to the position close to the drum 11 by the head separating / connecting device 31. Plate material 9 on the discharge head 22 and the drum 11
The distance to the surface is controlled to a predetermined distance during drawing by a mechanical distance control such as an abutting roller or a head separation / contact device controlled by a signal from an optical distance detector. Due to such distance control, the dot diameter does not become non-uniform due to floating of the plate material, and the dot diameter does not change particularly when vibration is applied to the plate making machine, and good plate making can be performed.

A single-channel head, a multi-channel head, or a full-line head can be used as the ejection head 22, and main scanning is performed by rotating the drum 11. In the case of a multi-channel head having a plurality of ejection portions or a full line head, the ejection portions are arranged in the axial direction of the drum 11. Further, in the case of a single-channel head or a multi-channel head, the image data calculation control unit 21 moves the discharge head 22 in the axial direction of the drum 11 for each rotation of the drum 11, and the discharge position and the mesh obtained by the above calculation. Oily 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 shading of the print document is drawn on the plate material 9 with the oil-based ink. This behavior is
The oil-based ink image for one color of the printing original is formed on the plate material 9 and continues until the printing plate is completed. On the other hand, when the ejection head 22 is a full line head having a length substantially the same as the width of the drum 11, one rotation of the drum 11 forms an oil-based ink image for one color of the printing original on the plate material 9. A printing plate is completed. By performing the main scanning by rotating the drum 11 in this manner, it is possible to improve the position accuracy in the main scanning direction and perform high-speed drawing.

Next, in order to protect the ejection head 22, the ejection head 22 is retracted away from the position close to the drum 11. This separating / connecting means operates so that the discharge head is separated from the drum by at least 500 μm or more except during drawing. The contact / separation operation may be performed by a slide method, 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 longer life can be achieved.

The formed oil-based ink image is strengthened by the fixing device 5. As the ink fixing means,
Known means such as heat fixing and solvent fixing can be used. In the heat fixing, irradiation with an infrared lamp, a halogen lamp or a xenon flash lamp, or hot air fixing using a heater, or heat roll fixing is generally used. In this case, the drum 9 is heated in order to improve 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 separate the plate material 9 from the above and heat only the plate material 9 alone or in combination.
Flash fixing using a xenon lamp or the like is known as a fixing method for electrophotographic toner, and has an advantage that fixing can be performed in a short time. When using a paper plate material,
Moisture inside the plate material evaporates rapidly due to the rapid temperature rise,
Since a phenomenon called blister occurs in which unevenness occurs on the surface of the plate material, the drum 1 is set so that the temperature of the paper plate material gradually rises.
It is preferable to gradually increase the power supply to the heat source while rotating 1 or to change the rotation speed from a high speed to a low speed with a constant power supply. It is also possible to arrange a plurality of fixing devices in the rotating direction of the drum 11 and change the distance to the plate material 9 and / or supply power to gradually increase the temperature of the paper plate material.

In the solvent fixing, a solvent capable of dissolving the resin component in the ink, such as methanol or ethyl acetate, is sprayed or exposed to vapor, and excess solvent vapor is collected. 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 to keep nothing on the image on the plate material 9.

An example of the construction of a plate-making device 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 comprises two pairs of cap stun rollers 1.
The image is drawn and carried by the inkjet drawing apparatus 2 by using the data which is nipped and conveyed by the image data No. 2 and is 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 the ink-jet drawing apparatus 2 draws, in order to serve as a counter electrode of the ejection head electrode in electrostatic field ejection, which facilitates drawing. On the other hand, when the base material of the plate material 9 has a high insulating property, it is preferable to provide a conductive layer on the base material. In this case, the conductive layer is formed on the conductive material layer by means of a known conductive brush, leaf spring, roller or the like. Grounding is desirable.

Although FIG. 2 shows an apparatus using a sheet plate material, a roll plate material is also preferably used, and in this case, it is desirable to provide a sheet cutter upstream of the automatic plate discharging apparatus.

The plate making apparatus 1 also has a fixing device 5 for strengthening the oil-based ink image drawn on the plate material 9. Further, a plate surface desensitizing device 6 used as necessary for the purpose of enhancing the hydrophilicity of the surface of the plate material 9 may be installed. Also,
The plate making device 1 is provided on the upstream side of the inkjet drawing device 2.
The adhesive roller 10 described above is rotatably arranged on the plate material 9. In the present embodiment, the adhesive roller 10 is composed of two or more adhesive rollers 10a and 10b having different adhesive strengths, one adhesive roller 10a is rolled on the plate material 9, and the adhesive roller 10a is adhered. The other adhesive roller 10b having a larger adhesive force than the adhesive force to the adhesive roller 10a.
Is in contact with. Therefore, the dust adhering to the adhesive roller 10a can be adsorbed and removed by the adhesive roller 10b. That is, the adhesive roller 10b functions as a cleaning roller for adsorbing and removing the dust of the adhesive roller 10a,
The reverse adhesion of dust from the adhesive roller 10a to the plate material is prevented.

Further, it is preferable to install an automatic plate feeder 7 for automatically supplying the plate material 9 and an automatic plate discharge device 8 for automatically removing the plate material 9 after drawing. By using the automatic plate feeding device 7 and the automatic plate discharging device 8, the plate making operation becomes simpler and the plate making time can be shortened, so that the effect of the present invention can be further enhanced.

Referring to FIG. 2 and part of FIG. 3, the plate making apparatus 1
The process of making a printing plate by means of will be described in more detail below.

First, the plate material 9 is conveyed by using the automatic plate feeder 7 and the cap stun roller 12. At this time, if necessary, by providing a plate material guide means (not shown) or the like, it is possible to prevent the plate head / butt of the plate material from flapping and coming into contact with and damaging the inkjet drawing device 2. Further, means for preventing the plate material 9 from slacking only around the drawing position of the inkjet drawing device 2 is provided, and at least when drawing is performed, this is applied to prevent the plate material 9 from contacting the inkjet drawing device 2. You can also do it. 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, and thereby it is possible to effectively prevent the occurrence of troubles such as contact damage in the inkjet drawing device 2.

Image data from the magnetic disk device, etc.
The image data calculation control unit 21 is supplied to 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 according to the input image data. These calculation data are temporarily stored in the buffer. The image data arithmetic control unit 21 controls the movement of the ejection head 22, the ejection timing control of the oil-based ink, the operation timing control of the cap stun roller, and the ejection head 22 is connected to the plate material 9 by the head separating / contacting device 31 as necessary. Move closer to the close position. The distance between the ejection head 22 and the surface of the plate material 9 is kept at a predetermined distance during drawing by controlling the mechanical distance such as an abutting roller or controlling the head contact / separation device based on a signal from an optical distance detector. Be done. Due to such distance control, the dot diameter does not become non-uniform due to floating of the plate material, and the dot diameter does not change particularly when vibration is applied to the plate making machine, and good plate making can be performed.

A single-channel head, a multi-channel head, or a full-line head can be used as the ejection head 22, and the sub-scanning is performed by transporting the plate material 9. In the case of a multi-channel head having a plurality of ejection parts, the arrangement direction of the ejection parts is set substantially parallel to the traveling direction of the plate material. Further, in the case of a single-channel head or a multi-channel head, the image data arithmetic control unit 21 moves the ejection head 22 in a direction orthogonal to the traveling direction of the plate material 9 every time the plate material moves, and the ejection obtained by the above calculation is performed. The oil-based ink is used for the plate material 9 according to the position and the dot area
To discharge. As a result, a halftone image corresponding to the shading of the print document is drawn on the plate material 9 with the oil-based ink. This operation is continued until an oil 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 a length substantially the same as the width of the plate material 9, the arrangement direction of the discharge parts is set to a direction substantially orthogonal to the traveling direction of the plate material 9 and the plate material 9 passes through the drawing part. By doing so, 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.

In order to protect the ejection head 22, the ejection head 22 is preferably retracted away from the position close to the plate material 9. The separating / contacting means operates so that the discharge head is separated from the plate material 9 by at least 500 μm or more except during drawing. The separating / contacting operation may be a slide type, or the ejection head may be fixed by an arm fixed to a certain shaft, and the arm may be moved around the shaft 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 longer life can be achieved.

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

In the 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 collected. 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 to keep nothing on the image on the plate material 9.

The obtained printing plate is printed by a known planographic printing method. That is, the printing plate on which the oil-based ink image is formed is mounted on a printing machine, printing ink and dampening water are applied to form a printing ink image, and the printing ink image is formed on the blanket cylinder rotating with the plate cylinder. One color printing is performed by transferring and then transferring the printing ink image on the blanket cylinder onto the 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 to be ready for the next printing.

Next, the ink jet drawing device 2 will be described. As shown in FIG. 3, the inkjet drawing apparatus 2 used in the plate making apparatus includes an inkjet ejection 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 means 29, and the ink tank 25 includes a stirring means 27 and an ink temperature management means 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
Suppresses the precipitation / aggregation of the solid components of the ink, and the need for cleaning the ink tank 25 is reduced. As the stirring means 27, a rotary vane, an ultrasonic vibrator, 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 changing the dot diameter. As a temperature control means for the ink, 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. A known method such as controlling with a thermostat or the like can be used.
The ink temperature in the ink tank 27 is 15 ° C or higher and 60
C. or less is desirable, more preferably 20.degree. C. or more and 50.degree. C. or less. The stirring means for keeping the temperature distribution in the ink tank 25 constant may be shared with the stirring means for the purpose of suppressing precipitation / aggregation of solid components of the ink.

Further, 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 the decrease in the solid content concentration in the ink, the jumping and blurring of the printed image, and the change in the dot diameter on the plate due to the increase in the solid content concentration. The ink density is measured by optical detection, measurement of electrical properties, measurement of physical properties such as viscosity, or control by the number of drawn images. In the case of managing by physical property measurement, an optical detector, an electric conductivity measuring instrument, a viscosity measuring instrument are provided individually or in combination in the ink tank 25 or the ink flow path, and drawing is performed by the output signal thereof. In the case of management based on the number of sheets, the liquid supply from the replenishing concentrated ink tank or the diluting ink carrier tank (not shown) to the ink tank 25 is controlled depending on the number of plates and the frequency.

As described above, the image data calculation control unit 21 calculates the input image data, and the head separating / contacting 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 installed on the drum 11 or the cap stun roller is fetched, and the ejection head 22 is driven according to the timing pulse. As a result, the positional accuracy can be improved.

Next, the ejection head 22 will be described with reference to FIGS.
The description will be made using 0. However, the content of the present invention is not limited to the following.

4 and 5 show an example of the ejection head provided in the ink jet drawing apparatus. Discharge head 22
Has a slit sandwiched by an upper unit 221 and a lower unit 222 made of an insulating base material, the tip of which is a discharge slit 22a, and a discharge electrode 22b is arranged in the slit. The ink 23 supplied from the inside is in a state where the slit is filled.
Examples of the insulating base material include plastic, glass,
Ceramics can be applied. In addition, the discharge electrode 22b
Are vacuum-deposited, sputtered, or electroless plated with a conductive material such as aluminum, nickel, chromium, gold, or platinum on the lower unit 222 made of an insulating base material.
A photoresist is applied on this, the photoresist is exposed through a mask having a predetermined electrode pattern, and the photoresist is developed to form a photoresist pattern of the ejection electrode 22b, which is then etched or mechanically removed. It is formed by a known method such as a method or a combination thereof.

In the ejection head 22, a voltage is applied to the ejection electrode 22b according to a digital signal of image pattern information. As shown in FIG. 4, the drum 11 serving as a counter electrode is provided so as to face the discharge electrode 22b,
A plate material 9 is provided on a drum 11 that serves as a counter electrode. By applying a voltage, a circuit is formed between the ejection electrode 22b and the drum 11 serving as a counter electrode, and the head 22
The oil-based ink 23 is ejected from the ejection slits 22a, and an image is formed on the plate material 9 provided on the drum 11 serving as a counter electrode.

The width of the ejection electrode 22b is preferably as thin as possible in order to form a high quality image. The specific numerical value varies depending on the conditions such as the applied voltage and the physical properties of the ink, but is usually used in the range of the tip width of 5 to 100 μm. For example, a discharge electrode 22b having a tip width of 20 μm is used, the 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 for 0.1 msec between the electrodes to form a 40 μm dot. The plate material 9
Can be formed on.

Further, FIGS. 6 and 7 show a schematic sectional view and a schematic front view, respectively, in the vicinity of the ink ejection portion of another ejection head example. In the figure, 22 is a discharge head, and this discharge head 22 has a first insulating base material 33 having a gradually decreasing shape. A second insulating base material 34 is provided on the first insulating base material 33 so as to face each other with a space therebetween, and a sloped surface portion 35 is formed at the tip of the second insulating base material 34. The first and second insulating base materials are formed of, for example, plastic, glass, ceramics or the like. A plurality of ejection electrodes 22b are provided on the upper surface portion 36 forming an acute angle with the inclined surface portion 35 of the second insulating base material 34 as an electrostatic field forming means for forming an electrostatic field in the ejection portion. The tips of the plurality of ejection electrodes 22b are extended to the vicinity of the tips of the upper surface portion 36, and the tips thereof are the first insulating base material 33.
The ejection portion is formed by projecting forward. An ink inflow path 37 is formed between the first and second insulating base materials 33 and 34 as a means for supplying the ink 23 to the ejection portion, and a lower side of the second insulating base material 34 is provided. An ink recovery path 38 is formed. The ejection electrode 22b is
A conductive material such as aluminum, nickel, chromium, gold, or platinum is used on the second insulating base material 34, and the same as above.
It is formed by a known method. The individual electrodes 22b are configured to be electrically insulated from each other.

The amount by which the tip of the ejection electrode 22b projects from the tip of the insulating base material 33 is preferably 2 mm or less. The reason why the amount of protrusion is preferably in the above range is that if the amount of protrusion is too large, the ink meniscus does not reach the tip of the ejection portion,
This is because ejection becomes difficult and the recording frequency is lowered. The space between the first and second insulating base materials 33 and 34 is preferably in the range of 0.1 to 3 mm. The reason why this space is preferable in the above range is that if the space is too narrow, it becomes difficult to supply the ink and ejection becomes difficult, 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, and when recording, a voltage is applied to the ejection electrode based on the image information to eject the ink on the ejection electrode, and Drawing is performed on a plate material (not shown) that is arranged so as to face each other. The direction opposite to the ink droplet ejection direction of the ink inflow path 37 is connected to an ink feeding means of an ink supply device (not shown). The second insulating base material 3
A backing 39 is provided on the surface opposite to the ejection electrode forming surface of No. 4 so as to face each other with a space therebetween, 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 will be difficult to collect the ink and ink leakage will occur. The ink recovery passage 38 is connected to an ink recovery means (not shown) of an ink supply device.

If 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. 7 shows a schematic front view of the vicinity of the ink ejection portion of the ejection head. On the slope of the second insulating base material 34, the ink recovery path 3 is formed from the vicinity of the boundary with the ejection electrode 22b.
8 are provided with a plurality of grooves 40. This groove 4
A plurality of 0s 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 of the ejection electrode 22b. Is discharged to the ink collecting path 38. Therefore, it has a function of forming an ink flow having a constant liquid thickness near the tip of the ejection electrode. The shape of the groove 40 may be in a range where a capillary force works, but it is particularly preferable that the width is 10 to 200 μm and the depth is 10 to 300.
It is in the range of μm. Further, the grooves 40 are provided in the required number so that a uniform ink flow can be formed over the entire surface of the ejection head.

The width of the ejection electrode 22b is preferably as thin as possible in order to form a high quality image. The specific numerical value varies depending on the conditions such as the applied voltage and the physical properties of the ink, but it is usually used in the range of the 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. 8 is a schematic view showing only a part of the head for explanation. The ejection head 22 is made of plastic, ceramic, or the like as shown in FIG.
It comprises a head body 41 made of an insulating material such as glass and meniscus regulating plates 42, 42 '. 22b in the figure
Is an ejection electrode to which a voltage is applied to form an electrostatic field in the ejection portion. Furthermore, from the discharge head 22 to the regulation plates 42,
The head main body will be described in detail with reference to FIG.

The head body 41 is provided with a plurality of ink grooves 43 for circulating ink perpendicularly to the edge of the head body. The shape of the ink groove 43 may be set in a range in which a capillary force works so that a uniform ink flow can be formed, but the width is particularly preferably 10 to 200 μm.
m, and the depth is 10 to 300 μm. A discharge electrode 22b is provided inside the ink groove 43. The ejection electrode 22b is formed by using a conductive material such as aluminum, nickel, chromium, gold, or platinum on the head body 40 made of an insulating material by a known method similar to the case of the above-described apparatus embodiment. It may be arranged on the entire surface of the groove 43 or may be formed on only a part thereof. The ejection electrodes are electrically isolated. Two adjacent ink grooves form one cell, and ejection portions 45 and 45 'are provided at the tip of the partition wall 44 at the center thereof. In the ejection portions 45 and 45 ', the partition wall is thinner than the other partition wall portions 44 and is sharpened. Such a head body is formed by a known method such as machining an insulating material block, etching, or molding. The thickness of the partition wall at the ejection portion is preferably 5 to 100 μm, and the radius of curvature of the sharpened tip is preferably in the range of 5 to 50 μm. The tip of the discharge part may be slightly chamfered like 45 '. Although only two cells are shown in the figure, the cells are partitioned by a partition wall 46, and a tip portion 47 thereof is chamfered so as to be retracted more than the discharge portions 45, 45 '.
To the ejection head, ink is supplied from an ink supply unit (not shown) through an ink groove from the direction I to supply the ink to the ejection unit. Further, the excess ink is recovered in the O direction by an ink recovery means (not shown), and as a result, fresh ink is constantly supplied to the ejection portion. In this state, a voltage is applied to the discharge electrode according to image information to a drum (not shown) having a plate material held on the surface thereof so as to face the discharge portion, whereby ink is discharged from the discharge portion. An image is formed on the material.

Another embodiment of the discharge head will be described with reference to FIG. As shown in FIG. 10, the ejection head 22 has a pair of substantially rectangular plate-shaped supporting members 50 and 50 '. These supporting members 50, 50 'are made of an insulating plate-like plastic having a thickness of 1 to 10 mm, glass, ceramics, etc., and one surface of each of them is parallel to each other depending on the recording resolution. Each of the grooves 51, 5 is formed with a plurality of elongated rectangular grooves 51, 51 '.
1'is preferably in the range of 10 to 200 μm in width and 10 to 300 μm in depth, and the ejection electrode 22b is formed in the whole or a part thereof. By thus forming the plurality of structures 51, 51 'on one surface of the support members 50, 50', a plurality of rectangular partition walls 52 are necessarily provided between the structures 51. Each support member 50, 50 '
Are combined so that the surfaces not forming the grooves 51, 51 'face each other. That is, the ejection head 22 has a plurality of grooves on the outer peripheral surface for circulating the ink.
Grooves 51, 51 'formed in each support member 50, 50'
Are connected in a one-to-one correspondence via the rectangular portion 54 of the ejection head 22, and the rectangular portion 54 to which each groove is connected is separated from the upper end 53 of the ejection head 22 by a predetermined distance (50 to 500 μm).
m) has retreated. That is, on both sides of each rectangular portion 54, the upper end 55 of each partition wall 52 of each support member 50, 50 'is provided.
Are provided so as to project from the rectangular portion 54. Then, the guide projections 56 made of an insulating material as described above are provided so as to project from each rectangular portion 54 to form a discharge portion.

When the ink is circulated through the ejection head 22 having the above-described structure, the ink is supplied to the rectangular portions 54 through the grooves 51 formed on the outer peripheral surface of the one supporting member 50, and the ink is supplied to the opposite side. Each groove 5 formed in the supporting member 50 'of
Discharge via 1 '. In this case, the ejection head 22 is inclined at a predetermined angle in order to enable smooth ink circulation. That is, the ejection head 22 is inclined so that the ink supply side (support member 50) is located above and the ink discharge side (support member 50 ') is located below.
In this way, when ink is circulated through the ejection head 22,
The ink passing through each rectangular portion 54 gets wet along each protrusion 56, and an ink meniscus is formed near the rectangular portion 54 and the protrusion 56. Then, in a state in which the ink meniscus is formed independently in each rectangular portion 54,
By applying a voltage based on image information to the discharge electrode 22b to a drum (not shown) having a plate material held on the surface thereof, the ink is discharged from the discharge section 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'. The ink may be forcibly circulated by. In this case, it is not necessary to tilt the ejection head 22.

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

As the image receiving layer, a hydrophilic layer composed of an inorganic pigment and a binder, or a layer which can be rendered 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 or the like can be used. As the binder, polyvinyl alcohol, starch,
Hydrophilic binders such as carboxymethyl cellulose, hydroxyethyl cellulose, casein, gelatin, polyacrylic acid salt, polyvinylpyrrolidone, and polymethyl ether-maleic anhydride copolymer can be used. Further, if necessary, a melamine formalin resin, a urea formalin resin, or other cross-linking agent that imparts water resistance may be added.

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

Zinc oxide used in the present invention is, for example, zinc oxide, zinc oxide, as described in “New Edition Pigment Handbook” edited by Japan Pigment Technology Association, page 319, Seibundou Co., Ltd. (published in 1968). Any of those commercially available as wet zinc white or activated zinc white may be used. That is, depending on the starting material and the manufacturing method, zinc oxide includes dry method, which is called French method (indirect method), American method (direct method) and wet method, such as Shodo Kagaku Co., Ltd. and Sakai Chemical Co., Ltd. ), Hakusui Chemical Co., Ltd., Honjo Chemical Co., Ltd., Toho Zinc Co., Ltd., Mitsui Kinzoku Kogyo Co., Ltd., and the like.

As the resin used as the binder, specifically, a styrene copolymer, a methacrylate copolymer,
Examples thereof include acrylate copolymers, vinyl acetate copolymers, polyvinyl butyral, alkyd resins, epoxy resins, epoxy ester resins, polyester resins, polyurethane resins and the like. These resins may be used alone or 2
You may use together 1 or more types. The content of resin in the image receiving layer is 9/91 to 2 in terms of the weight ratio of resin / zinc oxide.
It is preferably 0/80.

Desensitization of zinc oxide is carried out by a conventional method using a desensitizing treatment liquid, and conventionally, as a desensitizing treatment liquid of this kind, a cyanide compound containing ferrocyan salt or ferricyan salt as a main component is used. Containing treatment liquid, amminecobalt complex,
Phytic acid and its derivatives, cyan-free treatment liquid containing guanidine derivative as a main component, treatment liquid containing inorganic acid or organic acid forming a chelate with zinc ion as a main component,
Alternatively, a treatment liquid containing a water-soluble polymer is known. For example, as a cyanide-containing treatment liquid, JP-B-44-9045, JP-B-46-39403, and JP-A-52-52
-76101, 57-107889, 54-1
Examples thereof include those described in Japanese Patent No. 17201.

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

The Beck's smoothness can be measured by a Beck's smoothness tester. Beck's smoothness tester is a circular glass plate with a hole in the center that has been finished to a highly smooth surface. The test piece is pressed at a constant pressure (1 kgf / cm ² (9.8 N
/ Cm ² )), and the time required for a given amount (10 cc) of air to pass between the glass surface and the test piece under reduced pressure is measured.

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.

Specific electric resistance used in the present invention 10 ⁹ Ωcm
As the non-aqueous solvent having a dielectric constant of 3.5 or less, linear or branched aliphatic hydrocarbons, alicyclic hydrocarbons or aromatic hydrocarbons, and halogen-substituted products of these hydrocarbons are preferable. 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 (isopar: exon) Company name), SHERZOL 70, SHELSOL 71 (Shellsol: trade name of Shell Oil Co.), Amsco OMS, Amsco 460 solvent (AMSCO: trade name of Spirits Co., Ltd.), silicone oil, etc. either alone or mixed. To use. 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 within the above range is that when the electric resistance is low, concentration of resin particles and the like is less likely to occur, and sufficient printing durability cannot be obtained, and the dielectric constant is reduced. The reason for setting the above range is that when the dielectric constant is high, the electric field is relaxed due to the polarization of the solvent, and the ejection of the ink is likely to be deteriorated.

The resin particles dispersed in the above non-aqueous solvent may be particles of a hydrophobic resin which are solid at a temperature of 35 ° C. or lower and have good affinity with the non-aqueous solvent. Glass transition point is -5 ° C to 110 ° C or softening point is 33 ° C
The resin (P) having a temperature of ˜140 ° C. is preferable, and more preferably, the glass transition point is 10 ° C. to 100 ° C. or the softening point is 38 ° C. to 1.
20 ° C., more preferably glass transition point 15 ° C.
The softening point is 80 ° C or 38 ° C to 100 ° C.

By using such a resin having a glass transition point or a 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 strengthened. Therefore, the adhesion between the image area and the image receiving layer is improved, and the printing durability is improved. On the other hand, even if the glass transition point or the softening point is low or high, the affinity between the image receiving surface and the resin particles is lowered, or the bond 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 , and more preferably 1 × 10 ^{4 to} 5 × 10 ⁵ .

Specifically as such a resin (P),
Olefin polymers and copolymers (for example, polyethylene, polypropylene, polyisobutylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer,
Ethylene-methacrylate copolymer, ethylene-methacrylic acid copolymer, etc.), vinyl chloride polymer and copolymer (for example, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, etc.), vinylidene chloride copolymer, alkane Vinylate polymers and copolymers, allyl alkanoate polymers and copolymers, polymers and copolymers of styrene and its derivatives (for example, butadiene-styrene copolymers, isoprene-styrene copolymers, styrene-methacrylate copolymers) Polymers, styrene-acrylate copolymers, etc.), acrylonitrile copolymers, methacrylonitrile copolymers, alkyl vinyl ether copolymers, acrylic acid ester polymers and copolymers, methacrylic acid ester polymers and copolymers, Itaconic acid diester polymers and copolymers, maleic anhydride Phosphate copolymers, acrylamide copolymers, methacrylamide copolymers, Funinoru resin,
Alkyd resin, polycarbonate resin, ketone resin, polyester resin, silicone resin, amide resin, hydroxyl group and carboxyl group modified polyester resin, butyral resin, polyvinyl acetal resin, urethane resin, rosin resin, hydrogenated rosin resin, petroleum resin, hydrogenated resin Petroleum resin, maleic acid resin, terpene resin, hydrogenated terpene resin, coumarone-indene resin, cyclized rubber-methacrylic acid ester copolymer, cyclized rubber-acrylic acid ester copolymer, nitrogen ring-free heterocycle Copolymers contained (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. To be

The content of the dispersed resin particles in the oil-based ink of the present invention is preferably 0.5 to 20 wt% of the whole ink. When the content is low, the affinity between the ink and the surface of the printing original plate is difficult to be obtained, so that a good image cannot be obtained or the printing durability is deteriorated. When the amount is large, it is difficult to obtain a uniform dispersion liquid, and the ink flow in the ejection head is likely to be non-uniform, which makes it difficult to obtain stable ink ejection.

In the oil-based ink used in the present invention, it is preferable to include a coloring material as a coloring component together with the above-mentioned dispersed resin particles for inspecting a plate after plate making.
As the color material, any pigment and dye conventionally used in oil-based ink compositions or liquid developers for electrostatic photography can be used.

As the pigment, those commonly used in the technical field of printing can be used regardless of whether they are inorganic pigments or 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, slene 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 dye, azo dye, metal complex salt dye,
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 preferable. These pigments and dyes may be used alone or may be used in combination as appropriate, but are preferably contained in the range of 0.01 to 5% by weight based on the whole ink.

In addition to the dispersed resin particles, these coloring materials may be dispersed in the non-aqueous solvent as the coloring material itself as dispersed particles, or may be contained in the dispersed resin particles. When contained, the pigment and the like are generally coated with the resin material of the dispersed resin particles to form resin-coated particles, and the dye and the like are colored by coloring the surface portions of the dispersed resin particles to form colored particles. It is common.

The average particle size of these particles including resin particles dispersed in the non-aqueous solvent of the present invention and further colored particles is preferably 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 a mechanical grinding method,
If necessary, materials to be resin particles are mixed, melted and kneaded, and directly pulverized by a conventionally known pulverizer to obtain fine particles, and a dispersion polymer is used in combination, and a wet disperser (for example, ball mill, paint shaker) is used. , Keddy mill, Dyno mill, etc.), and the resin particle component material,
Examples thereof include a method of previously kneading a dispersion-aiding polymer (or a coating polymer) to form a kneaded product, pulverizing, and then allowing a dispersion polymer to coexist and disperse. Specifically, a method for producing a paint or a liquid developer for electrostatic photography can be used, and for example, for these, for example, Kenji Ueki, "Paint Flow and Pigment Dispersion," Kyoritsu Shuppan (1971), Solomon ". Science of paints "Hirokawa Shoten (1969), Yuji Nagasaki" Coating Engineering "Asakura Shoten (1971), Yuji Harazaki" Basic Science of Coating "Maki Shoten (1977), and other publications.

Further, as the polymerization granulation method, a conventionally known non-aqueous dispersion polymerization method can be cited. Specifically, it is described in Chapter 2, "Latest Technology of Ultrafine Particle Polymer" by Soichi Muroi, CMC Publishing (1991). ), Koichi Nakamura, "Recent Development and Practical Use of Electrophotographic Development System and Toner Material", Chapter 3, (Published by Japan Science Information Co., Ltd. in 1985), KEJBarrett "Dispersi
on Polymerization Organic Media "John Wiley (19
1975) and the like.

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

As a preferable soluble repeating unit of the dispersion polymer used in the present invention, a polymerization component represented by the following general formula (I) can be mentioned.

[0092]

[Chemical 1]

In the general formula (I), X ₁ is --COO.
Represents-, -OCO- or -O-. R has 10 carbon atoms
To 32 alkyl groups or alkenyl groups, preferably C10 to C22 alkyl groups or alkenyl groups, which may be linear or branched and are preferably unsubstituted, but have a substituent. You may have. Specific examples thereof include a decyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, an eicosanyl group, a docosanyl group, a decenyl group, a dodecenyl group, a tridecenyl group, a hexadecenyl group, an octadecenyl group, and a linolenyl group. .

A ₁ and a ₂ may be the same or different from each other, and are a hydrogen atom, a halogen atom (eg, chlorine atom, bromine atom, etc.), a cyano group, an alkyl group having 1 to 3 carbon atoms (eg, methyl group). group, an ethyl group, a propyl group, etc.), - COO-Z1 or -CH ₂ COO-Z ₁
[Z ₁ represents an optionally substituted hydrocarbon group having 22 or less carbon atoms (for example, an alkyl group, an alkenyl group, an aralkyl group, an alicyclic group, an aryl group, etc.)].

Of the hydrocarbon groups represented by Z ₁ , a preferred hydrocarbon group is an optionally substituted alkyl group having 1 to 22 carbon atoms (eg, methyl group, ethyl group, propyl group, butyl group, Hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tridecyl group,
Tetradecyl group, hexadecyl group, octadecyl group, eicosanyl group, docosanyl group, 2-chloroethyl group, 2
-Bromoethyl group, 2-cyanoethyl group, 2-methoxycarbonylethyl group, 2-methoxyethyl group, 3-bromopropyl group, etc.), an alkenyl group having 4 to 18 carbon atoms which may be substituted (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.),
Aralkyl groups having 7 to 12 carbon atoms which may be substituted (eg, 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 (eg, a cyclohexyl group, 2
-Cyclohexylethyl group, 2-cyclopentylethyl group, etc.) and optionally substituted aromatic group having 6 to 12 carbon atoms (eg, phenyl group, naphthyl group, tolyl group, xylyl group, propylphenyl group, butylphenyl group) , Octylphenyl group, dodecylphenyl group, methoxyphenyl group, ethoxyphenyl group, butoxyphenyl group, decyloxyphenyl group, chlorophenyl group, dichlorophenyl group, bromophenyl group, cyanophenyl group, acetylphenyl group, methoxycarbonylphenyl group, ethoxy Carbonylphenyl group, butoxycarbonylphenyl group, acetamidophenyl group, propionamidophenyl group, dodecyloylamidophenyl group, etc.).

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

The content of the polymer component represented by the general formula (I) in the dispersion polymer is preferably 50% by weight or more, more preferably 60% by weight or more. Specific examples of these dispersion polymers include the dispersion stabilizing resin (Q-1) used in the examples, and a commercially available product (Sorprene 1205, manufactured by Asahi Kasei Co., Ltd.) can also be used.

The dispersion polymer is preferably added in advance during the polymerization when the resin (P) particles are produced as a dispersion (latex) or the like. The amount of addition when the dispersion polymer is used is 1 to 50 with respect to the resin (P) for particles.
Set to about wt%.

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 electroscopic particles. It is possible to impart an electroscopic property to these particles by appropriately utilizing the technique of a developer for wet electrostatic photography. Specifically, the above-mentioned "Recent Development and Practical Use of Electrophotographic Development System and Toner Material" pp. 139 to 148, "The Basics and Applications of Electrophotographic Technology" edited by The Institute of Electrophotography, pp. 497-505 (Corona Publishing Co., Ltd., 1988).
Annual), Yuji Harasaki "Electronic Photography" 16 (No. 2), 44
Page (1977) and the like, and the use of a charge-detecting material such as a charge control agent and other additives.

Specifically, for example, British Patent No. 8934.
No. 29, No. 934038, No. 1122397,
U.S. Pat. No. 3,900,422, equivalent 4,606,989,
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 in the dispersion medium 10.
0.001 to 1.0 part by weight is preferable with respect to 00 parts by weight. If desired, various additives may be added, and the upper limit of the total amount of these additives is restricted by the electric resistance of the oil-based ink. That is, if the specific electric resistance of the ink with the dispersed particles removed is lower than 10 ⁹ Ωcm, it becomes difficult to obtain a good quality continuous tone image. Therefore, it is possible to control the addition amount of each additive within this range. desirable.

[0101]

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

<Production Example of Resin Particles (PL-1)> 10 g of dispersion stabilizing resin (Q-1) having the following structure and 10 parts of vinyl acetate.
A mixed solution of 0 g and Isopar H384 g was heated to 70 ° C. while stirring under a nitrogen stream. 0.8 g of 2,2'-azobis (isovaleronitrile) (abbreviation AIVN) was added as a polymerization initiator, and the reaction was carried out for 3 hours.
After 20 minutes from the addition of the initiator, white turbidity occurred and the reaction temperature was 8
It rose to 8 ° C. Furthermore, add 0.5 g of this initiator,
After reacting for 2 hours, the temperature was raised to 100 ° C. and stirred for 2 hours to distill off unreacted vinyl acetate. After cooling, it was passed through a nylon cloth of 200 mesh and the white dispersion obtained had a polymerization rate of 90.
%, The latex had an average particle size of 0.23 μm and good monodispersity. The particle size is CAPA-500 (Horiba Ltd.)
Manufactured).

[0103]

[Chemical 2]

A part of the white dispersion was subjected to a centrifugal separator (rotation speed 1 × 10 ⁴ rpm, rotation time 60 minutes) to collect and dry the precipitated resin particle component. Weight average molecular weight of resin particles (Mw: polystyrene conversion GPC
The value) was 2 × 10 ⁵ , and the glass transition point (Tg) was 38 ° C.

Next, 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), nigrosine 10 g, and shell sol 7
30 g of 1 was put into a paint shaker (manufactured by Toyo Seiki Co., Ltd.) together with glass beads 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 1., 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 to 1 liter of Isopar G.

Next, the ink jet tank 2 of the plate making apparatus (see FIGS. 1 and 3) was filled with 2 liters of the oil-based ink (IK-1) prepared as described above in the ink tank. Here, the discharge head is 900 dp shown in FIG.
i, 64 channel multi-channel head was used. As an ink temperature control means, a throw-in heater and a stirring blade were provided in the ink tank, the ink temperature was set to 30 ° C., and the temperature was controlled by 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. In addition, a part of the ink flow path is made transparent, and an LED light emitting element and a light detection element are arranged with the ink flow path sandwiched therebetween, and an output signal from the LED diluting solution (Isopar G) or concentrated ink (the above ink (IK-
The solid content concentration of 1) was adjusted to double), and the concentration was controlled by charging.

As a plate material, an aluminum plate having a graining and anodizing treatment and having a thickness of 0.12 mm was mounted by holding a plate head and a plate butt by a mechanical device provided on a drum of a plate making device. After removing dust on the surface of the plate material by suction with an air pump, bring the discharge head close to the plate material to the drawing position,
The image data to be plate-made was transmitted to the image data calculation control section, and the 64-channel discharge head was moved while rotating the drum to discharge the oil-based ink onto the aluminum plate to form an image. At this time, the tip width of the ejection electrode of the inkjet head was 10 μm, and the distance between the head and the plate material was controlled to be 1 mm by the output from the optical gap detection device. A voltage of 2.5 kV is always applied as a bias voltage, a pulse voltage of 500 V is further superimposed when performing ejection, and the pulse voltage is 256 steps in the range of 0.2 ms to 0.05 ms. Drawing was performed while changing the area of the dots by changing with.
No drawing defects due to dust were observed at all, and no image deterioration due to changes in dot diameter due to changes in outside temperature or an increase in the number of plate making was observed, and good plate making was possible.

Further, the image was solidified by heating with a xenon flash fixing device (manufactured by Ushio Inc., emission intensity 200 J / pulse) to prepare a printing plate. In order to protect the inkjet head, the inkjet drawing device together with the sub-scanning means is retracted by 50 mm from the position close to the drum, then the printing plate is taken out from the plate making device, and the oliver 2
Printing was carried out by mounting on a plate cylinder of a 66EPZ printing machine.

The obtained printed matter was an extremely clear image with no jumps or scratches on the printed image even after passing 10,000 sheets. Also, after plate making, the tip of the discharge head is
And a positive DC voltage of 1 kV was applied for 30 seconds to produce a printing plate that gives good printed matter for 6 months without requiring maintenance work.

Under the same conditions, the adhesive force of the adhesive roller is 7 hPa or more and 180 hPa or less (Example 1),
4 hPa or more and 7 hPa or less (Example 2), 180 hPa
Above 250 hPa (Example 3), below 4 hPa (Comparative Example 1), above 250 hPa (Comparative Example 2).
As a result, in Example 1, most of the dust adhering to the plate material can be adsorbed and removed by the adhesive roller, troubles such as clogging of the recording head do not occur, and clear images without defects such as printing stains can be obtained. It was Further, in Example 2, although dust remained on the printing plate to a small extent, there was no problem. Further, in Example 3, print stains were slightly seen depending on the print conditions, but the level was practically no problem. On the other hand, in Comparative Example 1, the dust adsorption capacity was small and it was impossible to remove the dust. Further, in Comparative Example 2, the hydrophilic surface of the plate material was scratched and stains occurred during printing.

[0111]

According to the present invention, in a plate making method in which an image is directly formed on a plate material and the image is fixed to form a printing plate, the image is formed on the plate material before and / or during the image formation. To
Since the adhesive roller rolls on the plate material to adsorb and remove the dust on the plate material, it is possible to prevent failures caused by the dust on the plate material adhering to the ejection head during image formation. , It is possible to create a printing plate that can print a large number of clear printed matter. Further, it is possible to prevent image defects caused by the ink adhering to the dust on the plate material. Further, a printing plate that directly corresponds to digital image data can be stably created with high image quality, and inexpensive and high-speed lithographic printing can be performed.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram schematically showing an example of a plate making apparatus used in the present invention.

FIG. 2 is an overall configuration diagram schematically showing another example of the plate making apparatus used in the present invention.

FIG. 3 is a configuration diagram schematically showing an example of a drawing unit of the plate making apparatus used in the present invention.

FIG. 4 is a schematic configuration diagram showing an example of an ejection head provided in the ink jet drawing device used in the present invention.

5 is a schematic cross-sectional view of the vicinity of the ink ejection portion of FIG.

FIG. 6 is a schematic cross-sectional view of the vicinity of an ink ejection portion in an example of another ejection head provided in the inkjet drawing device used in the present invention.

FIG. 7 is a schematic front view of the vicinity of the ink ejection unit of FIG.

FIG. 8 is a schematic configuration diagram showing a main part of an example of another ejection head provided in the inkjet drawing apparatus used in the present invention.

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

FIG. 10 is a schematic configuration diagram showing a main part of an example of another ejection head provided in the inkjet drawing apparatus used in the present invention.

[Explanation of symbols]

1 Plate making equipment 2 Inkjet drawing device 5 Fixing device 6 Plate desensitizing device 7 Plate material automatic plate feeder 8 Automatic plate discharge device 9 Plate material (printing original plate) 10 Adhesive roller 11 drums 12 Cap Stan roller 13 Grounding means 21 Image data calculation controller 22 Discharge head 221 Upper unit 222 Lower unit 22a discharge slit 22b Discharge electrode 23 Oil-based ink 24 Ink supply section 25 ink tanks 26 Ink supply device 27 stirring means 28 Ink temperature control means 29 Ink density control means 30 encoder 31 Head contact / separation device 32 head sub-scanning means 33 First Insulating Base Material 34 Second insulating base material 35 Slope of second insulating base material 36 Upper surface of second insulating base material 37 Ink flow path 38 Ink collection path 39 backing 40 grooves 41 head body 42, 42 'Meniscus regulated version 43 ink groove 44 partition 45, 45 'Discharge part 46 partitions 47 Partition tip 50, 50 'support member 51, 51 'groove 52 partition 53 Upper end 54 rectangle 55 Top of partition 56 Guide protrusion

Claims (5)

[Claims] 1. An image is directly formed on a plate material by an electrostatic ink jet system in which an oil-based ink is ejected from an ejection head using an electrostatic field based on a signal of image data.
A plate making method of fixing the image to form a printing plate, comprising rolling an adhesive roller on the plate material before and / or during image formation on the plate material. A plate-making method characterized by adsorbing and removing the dust of. 2. The plate making method according to claim 1, wherein the adhesive force of the adhesive roller is 4 hPa or more and 250 hPa or less. 3. An image forming means for directly forming an image on a plate material on the basis of a signal of image data, and an image fixing means for fixing the image formed by the image forming means to obtain a printing plate. The image forming unit is a plate making apparatus that is an inkjet drawing apparatus that discharges an oil-based ink from an ejection head by using an electrostatic field, and the upstream side in the plate material moving direction of the inkjet drawing apparatus,
A plate making apparatus, wherein an adhesive roller for adsorbing and removing dust on the plate material is provided so as to be rollable on the plate material. 4. The plate making apparatus according to claim 3, wherein the adhesive force of the adhesive roller is 4 hPa or more and 250 hPa or less. 5. The pressure-sensitive adhesive roller is composed of two or more pressure-sensitive adhesive rollers having different pressure-sensitive adhesive forces, one pressure-sensitive adhesive roller is rolled on a plate material, and a pressure-sensitive adhesive force larger than the pressure-sensitive adhesive force of the one pressure-sensitive adhesive roller. 5. The plate making apparatus according to claim 4, wherein another adhesive roller having a is brought into contact with the one adhesive roller.