JP2004050575A - On-board drawing lithographic printing method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing method which includes a cleaning step for efficiently removing the ink receiving region of a master, and especially, creates the ink receiving region directly corresponding to digital image data using an ink jet recording device and stably/simply creates an endless printing plate capable of printing many sheets of sharply imaged printed matter, and a related printing device. <P>SOLUTION: A made-up roll 1 has a chrome-plated satin-like surface having water/oil retention characteristics and serves as a plate cylinder by forming a grease-sensitive ink-applied part of positive information using an ink jet image-drawing device 4. The plate cylinder transfers an oil ink image to a blanket cylinder 2 by first applying dampening water, then printing with the dampening water and an oil ink and depositing the oil ink on the ink-applied part. Next, the oil ink image of the blanket cylinder 2 is transferred to printing sheet W passing between the cylinder 2 and an impression cylinder 3. Thus a one color printing job is completed. After that, the satin-like surface of the roll 1 is activated and restored to its original condition with high absorptivity and water/oil retention characteristics by cleaning the satin-like surface using a solvent cleaning means 10, an electrolytic degreasing means 11, a water cleaning means 12 and a wiping/cleaning means 13. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention includes a cleaning step so that the ink receiving area of the print master can be effectively removed and the substrate of the print master can be reused in the next printing cycle, particularly using an inkjet recording device. On-press lithographic printing method and on-press, which can create an ink-receiving area corresponding to digital image data directly and stably and easily create an endless printing plate capable of printing a large number of prints of clear images The present invention relates to a lithographic printing apparatus.
[0002]
[Prior art]
First, a part of the column described in the prior art of Japanese Patent Application Laid-Open No. 2002-127355 is quoted in its entirety below.
Today, the most important printing method, offset printing, is based on the incompatibility of water and oil-based printing inks. In that case, the non-printed part of the offset plate is so as to be in a hydrophilic state, i.e. to accept water or dampening agent, whereas the printed part of the offset plate is in a hydrophobic state. I.e., not treated with water or dampening agents.
For example, if the plate applied on the plate cylinder is wetted, only the hydrophilic parts are wetted and, subsequently, when the plate is inked, the oil-based printing ink is hydrophobic and at the same time lipophilic, ie accepts oil. Applied to plates only at the site.
The printed image produced in this way is subsequently transferred from the plate cylinder to a rubber blanket cylinder, and therefrom under pressure to a print carrier, for example a paper, carton or sheet. The offset method is therefore an indirect printing method.
[0003]
Conventional plates used in offset printing usually have a roughened surface on the non-printed part by a mechanical and / or electrolytic process, where a dampening film is applied. It consists of a pre-coated aluminum plate with micropores or pores that have been received and retained.
In contrast, in the printing section, the plate has a fine, closed surface, which does not accept dampening agents, but which provides a good adhesion base for printing inks.
However, this plate can only be imaged once, and it is not possible to subsequently erase the print image and re-apply a new print image. (End of quote)
[0004]
Subsequently, a part of the description column in the conventional art of Japanese Patent Application Laid-Open No. 2002-160344 is quoted in its entirety below.
In conventional lithographic printing, ink and fountain solution are supplied to the surface of a print master containing ink-receptive (lipophilic) and water-receptive (hydrophilic) regions. The inked image pattern is then transferred from the surface of the master to a blanket cylinder having a compressible surface. The image is printed on the paper from the blanket cylinder. The master is typically a printing plate having the image on a dimensionally stable substrate such as an aluminum sheet. The imaged aluminum plate is fixed to the plate cylinder of the printing press by a mechanical fixing mechanism that defines the positional register between the plate and the surface of the cylinder. After the printing operation, the mechanical fixing system can be released and the printing plate with the printed image can be removed and discarded, and another printing plate can be placed and locked in place. Then a new printing operation can be started.
[0005]
Print masters are generally obtained by a so-called computer-to-film method, in which each color selection is transferred to a graphic arts film using an image-setter.
After processing, the film can be used as a mask for exposure of an imaging element, referred to as a plate precursor, and a printing plate is obtained that can be used as a master after plate processing. These steps are generally performed in dedicated exposure and processing equipment and the printing plate is then sent to the printing press and by the operator of the printing press using a locking mechanism incorporated into the cylinder itself. Attached to the printing cylinder. Although the mounting of the printing cylinder is generally a manual operation, robotic means have been developed for positioning and fixing the printing plate.
[0006]
In recent years, the so-called computer-to-plate method has gained many advantages.
This method, also referred to as a direct-to-plate method, avoids the creation of a film because the digital data is transferred directly to the plate precursor by a so-called plate setter.
On-press imaging is a direct-to-press method, also referred to as direct-to-press, in which the plate is placed on a plate cylinder of the press. The image is exposed on the plate as it is.
The main advantage of the latter method over off-press plate making is the improved registration between the presses of a multicolor press.
[0007]
Two types of such on-press imaging methods are known.
According to the first type, the printing plate precursor is placed on a printing press, imagewise exposed, optionally developed, and then used as a printing master and finally removed from the printing press and discarded Need new plate material for each image.
An example of this technique is the Heidelberg Model GTO-DI manufactured by Heidelberg Druckmaschinen AG (Germany) which is described in detail in US Pat. No. 5,339,737.
A disadvantage of this method is the need to use a new plate for each press operation, which increases the cost of the printing method. (End of quote)
[0008]
The above-described image forming method on a printing press is a system for recording an image in a light mode or a thermal mode using a laser. After recording, the image is processed with an alkaline developing solution to dissolve and remove a non-image portion to perform plate making. Alkaline waste liquid is discharged, which is not preferable for environmental protection. Moreover, it becomes an expensive and large apparatus.
Therefore, as an inexpensive and simple method, a digitally compatible plate making method and plate making device that does not require a development process that enables the production of a lithographic printing plate capable of producing a large number of clear and high-quality printed materials, is provided by inkjet printing on a printing machine. There have been proposed offset plate making methods and apparatuses that perform drawing and plate making. For example, there are JP-A-2002-127354 and JP-A-2002-127353.
Note that, although not on a printing press, Japanese Patent Application Laid-Open No. 64-27953 discloses an offset plate making method for performing plate making by drawing with an ink jet.
However, the printing plate precursor is placed on the printing press, the image is image-drawn by inkjet, and then used as a printing master and finally removed from the printing press and discarded for each image with a new plate. Requires material. Therefore, the disadvantage of this method is also the need to use a new plate for each press operation, which has not been improved in that it increases the cost of the printing method.
Further, the central mode of the embodiment is that the nozzle of the ink jet recording apparatus is brought close to the plate material wound around the drum, and a relative scanning operation is performed between the drum and the nozzle, and ink is ejected from the nozzle to form the plate material. This is a device that draws a positive image and fixes it, prepares a hydrophilic sheet-shaped plate material, winds it around a drum by the cooperation of an automatic plate feeding device and a plate head / butt holding device, and an automatic plate discharging device. The plate material wound around the drum is removed by the cooperation of the plate head / butt holding device.
Equipped with an automatic plate feeding device and an automatic plate discharging device, and a plate head / butt holding device in the drum is complicated in structure and often impairs the function, and is a major cause of failure and maintenance.
Since the printing plate is a sheet and is not endless, a portion of the printing material corresponding to the portion of the printing plate that has no printing plate from end to end is wasted. In this case, the radius of rotation of the plate surface becomes large in this portion, causing a problem such as contact damage to the ink jet drawing apparatus, and also hindering smooth rotation.
[0009]
Again, a part of the column described in the prior art of Japanese Patent Application Laid-Open No. 2002-127355 is quoted in its entirety below.
Further plates are known which can be imaged multiple times. This plate has, for example, a surface that can reversibly transition from a hydrophobic state to a hydrophilic state.
[0010]
EP-A-0 911 154 describes a version whose surface is coated with titanium oxide or zinc oxide. The surface properties of this plate preferably change from a hydrophobic state to a hydrophilic state under the action of UV light with a wavelength of less than 400 nm. In addition, the plate can again be converted to a hydrophobic state, which is simultaneously a lipophilic state, again under the action of heat provided by, for example, an infrared laser or a thermal element device. A printed image can be produced by irradiating the coated plate, which is initially in a hydrophobic or lipophilic state, entirely with UV light to make it entirely hydrophilic. Heat is subsequently applied locally to the area to be printed, for example by means of a thermal element device, so that the plate is locally imaged, i.e. locally hydrophilic. Thereafter, when the printing ink and the dampening agent are applied to the surface of the plate, the printing ink and the dampening agent respectively adhere to the sites receiving them, so that the plate is ready for printing. After printing, the printing ink is first washed out of the printing form in a washing device and is again returned to a completely hydrophilic state by the new action of UV radiation. The printed image thus disappears from the plate and can be processed in a further image application process.
[0011]
EP-A-0 911 155 furthermore discloses plates which are likewise coated with titanium oxide or zinc oxide, which, like the plate described in EP-A-0 911 154, It can be converted to a hydrophilic state using UV radiation and to a lipophilic state using heat. The described plate is initially in a lipophilic state and is locally exposed to UV radiation only to the non-printed areas, changing this part to a hydrophilic state. Thus, the plate is negatively imaged. After printing, the printing ink is firstly washed away from the printing form and subsequently returned entirely to the lipophilic state by a heat treatment, thereby erasing the image and preparing it for a further imaging process.
[0012]
Erasing the image of said plate, however, requires several minutes, for example, about 10 minutes at a temperature of about 150 ° C. This time can only be reduced by increasing the temperature. For example, to achieve an erase time of 10 seconds, the temperature must already be raised to 250 ° C. during the heat treatment. In this case, a continuous reduction of the erasing time, on the one hand, temperature tolerance, in particular decomposition of the oxide layer by thermal action, on the other hand, for example, the temperature of the erasing device which may be present in the printing press as well as the temperature of the printing press itself Instability hinders. In the case of applying direct printing, i.e. in the case of sending image data directly from a computer to a printing press, however, the printing and erasing of the plate must take place in the printing press, and at the same time the time of both processes, In particular, it must be possible to carry out a rapid plate change with the time of the erasing process being minimized. However, plates erased according to the prior art must therefore be very heated and therefore have to pass through a cooling phase before the subsequent imaging process, whereby the overall time for reimaging is reduced. It again increases undesirably.
[0013]
Furthermore, it is known that the hydrophilic effect of the plate is lost again in a few hours or in a few weeks on storage in the dark, due to the modification of the titanium dioxide. On the molecular plane, in this case, the OH groups providing the hydrophilicity are released, and instead oxygen is deposited, which causes the surface to be hydrophobic.
[0014]
Also used as reimageable plates are plates that are newly coated with a surface that can be imaged in a coating process after the cleaning process. In this case, the printing-critical surface layer remains unchanged in the molecular range and is not erased, but the already imaged layer is covered by a layer which has not yet been imaged. (End of quote)
[0015]
From the above, in the invention proposal of JP-A-2002-127355, an erasing agent is used and ultrasonic cleaning is performed.
[0016]
Again, a part of the column described in the prior art of Japanese Patent Application Laid-Open No. 2002-160344 is quoted below in its entirety.
In an imaging system on a second type of press, the same lithographic substrate is used in multiple printing operations (hereinafter referred to as a printing cycle).
At each printing cycle, a heat-sensitive or light-sensitive layer is coated on a lithographic substrate to produce a printing plate precursor and a print master is obtained after image-wise exposure and optional development.
After press operation, the ink-receiving area of the print master is removed from the lithographic substrate in a cleaning step to recirculate the substrate and to be used in the next cycle of coating, exposing and printing without having to install a new plate on the cylinder. can do.
Examples of such on-press coating and on-press imaging systems are described, for example, in US 5,188,033, US 5,713,287, EP-A 789 337 and EP-A 802 457. ing.
The latter patent application discloses a printing member, means for applying a uniform coating, means for exposing the uniform coating according to an image pattern in a scan-wise manner, and developing the uniform coating to form an image on the printing member. An image comprising an ink-receptive area on an ink-repellent background or an ink-repellent area on an ink-receptive background. According to a preferred embodiment, the coating comprises hydrophobic thermoplastic polymer particles in a hydrophilic binder.
[0017]
All cleaning liquids for lithographic printing plates are described in EP-A 0 211 176, EP-A 0 211 177 and EP-A 0 211 178 and DE-A 4 216 636, filed on Jan. 18, 2000. ing.
[0018]
Known cleaning fluids typically contain solvents that are harmful to hoses, pumps and seals and / or are very thorough with water because these fluids are not compatible with the coating step during the next printing cycle Requires rinsing.
[0019]
Known on-press coating methods provide an adequate balance between the chemical reactivity of the cleaning liquid on the ink-receptive area that must be removed on the one hand and the required inertness of the cleaning liquid on the brittle lithographic surface on the other hand. Cleaning of the lithographic substrate often fails because a compromise cannot be found. Typical lithographic surfaces are very sensitive, both mechanically and chemically. In order to differentiate the spreading properties of the ink and the fountain solution, the lithographic surface generally comprises a microporous structure. Anodized aluminum plates comprise a lithographic surface that contains one or more metal oxides on which absorption phenomena can occur. These metal oxides are very susceptible to chemical conversion to a form that is no longer lithographically active.
[0020]
The above microporosity of the lithographic surface is also very susceptible to mechanical damage. The presence of solid particles in the cleaning liquid, which is often required for effective mechanical cleaning of the lithographic surface, inevitably results in disturbance of the surface microstructure. Because the ink and the coated imaging layer penetrate into the microporous structure, it is necessary to perform vigorous cleaning to avoid ghosting due to incomplete removal of the previous image in the next printing cycle . (End of quote)
[0021]
From the above, in the invention proposal of JP-A-2002-160344, a negative-working image-forming material is applied by applying a coating solution containing hydrophobic thermoplastic particles and a hydrophilic binder on a hydrophilic surface. To produce a printing master having an ink-receiving area by exposing the image-forming material image-wise, applying ink and fountain solution to the printing master, and applying the ink-receiving area to the printing master for the organic compound. A direct-to-plate lithographic printing method using a reusable substrate having a hydrophilic surface, comprising a step of removing by performing a cleaning using a cleaning liquid comprising an underwater emulsion. are doing.
[0022]
[Problems to be solved by the invention]
As described above, the plate is initially in a lipophilic state, and is locally irradiated with UV rays only to the non-printed area to change this part to a hydrophilic state, and after printing, the remaining printing ink is washed from the plate. Negative-working imaging material by removing it and then heat-treating it entirely to a lipophilic state, or by applying a coating solution comprising hydrophobic thermoplastic particles and a hydrophilic binder on the hydrophilic surface In the process of forming the ink-receiving area by exposing the image forming material image-wise, the ink-receiving area corresponding to the digital image data is directly formed using an inkjet recording device, which is not simple. There is no room.
[0023]
According to the present invention, an ink receiving area corresponding to digital image data can be directly formed on the surface of an endless roll by using an ink jet recording apparatus, and an endless printing plate capable of printing a large number of clear printed images can be stably formed. Automatic plate feeder, which includes a cleaning stage that can be easily and easily prepared, after printing is completed, the ink receiving area of the print master can be effectively removed and the substrate can be reused in the next printing cycle. The present invention relates to an on-machine drawing lithographic printing method and an on-machine drawing lithographic printing apparatus which do not require a printing machine, an automatic plate discharging device, a plate head / butt holding device, and the like.
[0024]
[Means for Solving the Problems]
The invention of [Claim 1] provides a printing machine in which the outer peripheral surface is subjected to chrome plating and further subjected to a satin finish so that the surface tension is maximized due to the roughening-enlargement of the surface area, and the hydrophilic / lipophilic property region is increased. Attach a plate-making roll with a matte surface with high water retention and oil retention properties with high adsorptivity, clean and activate the surface of the plate-making roll and bring the inkjet nozzle of the inkjet recording device close to the surface. By applying a required relative scanning operation to the plate making roll and the ink jet nozzle to eject ink from the ink jet nozzle based on the digital image data to form a positive image ink receiving area on the plate making roll to form a plate cylinder, A dampening solution and oil-based ink are supplied to the plate cylinder, oil-based ink is applied to the ink receiving area, and the image pattern of the oil-based ink applied to the ink receiving area is transferred to the plate cylinder. The printing is performed by transferring the image pattern of the oil-based ink to a printing material passing between the blanket cylinder and the impression cylinder while being pressed between the blanket cylinder and the impression cylinder. It is an object of the present invention to provide an on-press lithographic printing method characterized by cleaning an image pattern of an oil-based ink and an ink-receiving area remaining on a printing plate so that they can be reused in the next printing cycle.
The invention according to claim 2 is a cleaning step, wherein the cleaning includes a first step of removing an image pattern and an ink receiving area of the oil-based ink remaining on the surface of the plate-making roll with a solvent; The on-press lithographic printing apparatus according to [1], wherein a combination of a second stage treatment of electrolytically degreasing the roll surface and a third stage treatment of cleaning the roll surface with water is provided. It is in.
According to a third aspect of the present invention, there is provided an image of an oil-based ink applied to an ink-receiving area formed on a plate cylinder by supplying dampening water and oil-based ink to the plate cylinder, and applying the oil-based ink to the ink-receiving area. The pattern is transferred to a blanket cylinder that rolls and rotates in contact with the plate cylinder, and the image pattern of the oil-based ink is transferred to a printing object that is sandwiched between the blanket cylinder and the impression cylinder, and printed. In an on-press drawing lithographic printing apparatus for cleaning the image pattern and ink receiving area of the oil-based ink remaining on the surface of the plate making roll so that they can be reused in the next printing cycle,
In the plate cylinder, the base material is chrome-plated on the outer peripheral surface, and is further subjected to satin finish.The surface tension is maximized by increasing the surface area, and the surface tension is maximized. It is a plate-making roll with a pear surface having high water retention and oil retention,
An ink jet nozzle is brought close to the plate making roll and a required relative scanning operation is applied to the plate making roll and the ink jet nozzle to eject ink from the ink jet nozzle based on the digital image data to receive a positive image ink on the plate making roll. Equipped with an ink jet printer device that forms an area,
A cleaning means for cleaning the image pattern of the oil-based ink remaining on the surface of the plate making roll and the ink receiving area after printing is completed so that the ink receiving area can be reused in the next printing cycle. An object of the present invention is to provide an upper drawing planographic printing apparatus.
According to a fourth aspect of the present invention, the cleaning means includes a solvent cleaning means for removing an image pattern and an ink receiving area of the oil-based ink remaining on the surface of the plate making roll with a solvent as a first step processing; It is characterized by a combination of electrolytic degreasing means for immersing the plate making roll in a negative electrode in a negative electrode as a two-step treatment and electrolytically degreasing the roll surface and water washing means for washing the roll surface with water as a third step treatment. An object of the present invention is to provide an on-press lithographic printing apparatus according to [claim 3].
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
The on-press lithographic printing method and the on-press lithographic printing apparatus of the present invention will be described with reference to FIG.
FIG. 1 shows an overall configuration diagram of an on-press lithographic printing apparatus for monochrome printing.
As shown in FIG. 1, the on-press lithographic printing apparatus has a plate-making roll 1, a blanket cylinder 2, and an impression cylinder 3, one at a time. A blanket cylinder 2 for transfer is arranged so as to be in pressure contact, and an impression cylinder 3 for transferring a printing ink image transferred to the blanket cylinder 2 to a printing web W is arranged so as to be in pressure contact with the blanket cylinder 2.
[0026]
The plate-making roll 1 has an outer peripheral surface obtained by applying a thick chromium by electroless plating to a base material roll of a shaft type or a sleeve type made of aluminum, iron, or the like by electroless plating and precision cylindrical polishing. The surface area is maximized by shot blasting, liquid honing using a lapping abrasive, electrolytic treatment, chemical treatment, etc., roughening-surface area is increased to maximize surface tension, and hydrophilic / lipophilic physical properties It has a pear surface with high water retention and oil retention that is highly adsorbent.
The ink receiving area of the positive image is formed on the plate-making roll 1 by the ink jet recording device to form a plate cylinder.
Chromium plating has no oil repellency and water repellency from the beginning, as can be seen from the gravure plate roll, and is hydrophilic and lipophilic. When chrome plating is matte-finished, the surface tension is maximized by roughening-increasing the surface area, and it has high water retention and oil retention properties with high adsorptivity beyond the physical property range of hydrophilicity and lipophilicity. . In addition, you may perform the desensitization process which has a permanent effect as needed after pear-time processing.
By jetting a lipophilic or lipophilic ink that does not spread out due to strong adhesion, the ink can be stably applied to this part, and this ink is used as an oil-based ink for offset printing. It can be an attachment part. Once the ink-coated part is formed, the dampening solution should be brought into contact with the parts other than the ink-coated part sufficiently before contact with the inking roll. Oil-based ink does not adhere during offset printing.
[0027]
In accordance with the plate-making roll 1, an ink jet recording device 4, an image data operation control unit 5, a dampening solution supply device 6, a printing ink supply device 7, an ink fixing device 8, and a solvent cleaning device 10 as a cleaning device. An electrolytic degreasing means 11, a water washing means 12, and a wiping means 13 are provided. It is to be noted that a desensitizing means 9 for providing water retentivity to the satin surface of the plate making roll 1 is provided as necessary.
Further, a blanket cylinder cleaning unit 14 is provided corresponding to the blanket cylinder 2, and an impression cylinder cleaning unit 15 is provided corresponding to the impression cylinder 3.
Then, the printing web W is supplied by the paper feeding device 16 so as to wind around the impression cylinder 3, and is transported so as to be pressed by the blanket cylinder 2. Paper dust generation preventing means 17 is provided upstream of a position where the printing web W is pressed between the blanket cylinder 2 and the impression cylinder 3.
[0028]
The ink jet recording apparatus 4 discharges oil-based ink onto the plate making roll 1 to form an image in accordance with the image data sent from the image data calculation control unit 5. The plate-making roll 1 is preferably provided with a grounding means such as a brush, a leaf spring, a roller, etc., because the plate-making roll 1 is a counter electrode of the discharge head electrode in electrostatic field discharge.
The inkjet recording device 4 includes the inkjet recording device 4 and an ink supply unit. The ink supply unit has an ink tank, an ink supply device, and an ink density control unit. The ink tank includes a stirring unit and an ink temperature management unit. The ink may be circulated in the head. In this case, the ink supply unit also has a collecting and circulating function. The stirring means suppresses precipitation and aggregation of the solid components of the ink. As the stirring means, a rotary blade, an ultrasonic vibrator, and a circulation pump can be used, and these are used or in combination. The ink temperature management means is arranged so that high-quality images can be stably formed without changing the dot diameter or the physical properties of the ink due to a change in the surrounding temperature.
The head moving means 4b can support the ink jet recording apparatus 4 and move two-dimensionally in a direction approaching and separating from the plate making roll 1 and a direction going along the plate making roll 1.
In the inkjet nozzle 4a, a voltage is applied to the ejection electrode in accordance with the digital signal of the pattern information of the image, and a circuit is formed between the inkjet printing plate 4 and the plate-making roll 1 which is a counter electrode in a form facing the ejection electrode. An oil-based ink is discharged from the substrate to form an image on the plate-making roll 1 serving as a counter electrode.
[0029]
The image data calculation control unit 5 receives image data from an image scanner, a magnetic disk device, an image data transmission device, etc., performs color separation, and divides the separated data into an appropriate number of pixels and gradations. In order to draw the oil-based ink image using the inkjet nozzles 4a of the inkjet recording apparatus 4, the positions and area ratios of the halftone dots are calculated. In addition to controlling the ink ejection timing, the operation timing of the plate-making roll 1, blanket cylinder 2, impression cylinder 3 and the like is controlled as necessary.
[0030]
The dampening water supply device 6 supplies dampening water to the hydrophilic portion (non-image portion) formed on the plate making roll 1 and may be any of a Molton water supply system, a synflo water supply system, a continuous water supply system, and the like.
The printing ink supply device 7 is provided downstream of the dampening solution supply device 6.
The ink fixing means 8 improves the adhesion of the drawn oil-based ink image to the plate making roll 1. As the fixing means for the ink, known means such as heat fixing, solvent fixing, and UV exposure fixing can be used. In the heat fixing, irradiation with an infrared lamp, a halogen lamp, a xenon flash lamp, or hot air fixing using a heater can be used.
[0031]
The solvent cleaning means 10, the electrolytic degreasing means 11, and the water cleaning means 10 have substantially the same mechanical structure.
[0032]
The solvent cleaning means 10 is first operated for renewing the plate after printing is completed. When the chamber 10a is brought close to the plate-making roll 1, two solvent-resistant parts provided in the chamber 10a are used. The rubber roll 10b can be in rolling contact with the rotatably driven plate-making roll 1 to secure a partition for preventing scattering, and is provided at equal intervals on a pipe provided to reciprocate with a small stroke in the chamber 10a. The nozzle 10c made of stainless steel is opposed to and close to the plate-making roll 1 and is oscillated along the plate-making roll 1 while spraying a solvent from the nozzle 10c to form an image of the oil-based ink remaining on the surface of the plate-making roll 1. It serves to dissolve and remove the pattern and the ink receiving area.
[0033]
The electrolytic degreasing means 11 is a means for completely removing traces of oil-based ink and the ink composition which has formed the ink receiving area, which are still firmly adhered even after the solvent washing, and operates after the solvent washing. When the chamber 11a is brought close to the plate-making roll 1, two rubber rolls 11b provided in the chamber 11a and having resistance to the alkaline electrolytic degreasing solution are brought into rolling contact with the rotationally driven plate-making roll 1. A partition for preventing scattering can be secured, and a stainless steel nozzle 11c provided at equal intervals on a pipe provided so as to reciprocate with a small stroke in the chamber 11a is opposed to and close to the plate-making roll 1, and is covered. While oscillating along the plate making roll 1, an alkaline electrolytic degreasing solution is sprayed from the nozzle 11c to the plate making roll 1 and each nozzle 11c is positively irradiated. An oil-based ink that secures electrode wiring so that the plate-making roll 1 becomes a cathode, supplies an electrolytic current, generates hydrogen gas from the surface of the plate-making roll 1 and firmly adheres to the surface of the plate-making roll 1; It serves to physically peel off the ink receiving area. In this case, the reaction between chromium and alkali that would destroy the chrome-plated satin surface does not occur by electrolytic degreasing.
[0034]
The water washing means 12 is operated after the completion of the alkaline electrolytic degreasing, and when the chamber 12a is brought close to the plate-making roll 1, two rubber rolls 12b having resistance to the alkaline electrolytic degreasing liquid provided in the chamber 12a are provided. The nozzle is provided at equal intervals on a pipe provided in the chamber 12a so as to reciprocate with a small stroke by rolling contact with the plate-making roll 1 which is driven to rotate, thereby securing a partition for preventing scattering. The pure water, distilled water, or tap water passed through a filter is jetted from the nozzle 12c to the plate making roll 1 while the nozzle 12c is oscillated along the plate making roll 1 while being opposed to the plate making roll 1. It plays the role of washing away the alkaline electrolytic degreasing solution adhering to the surface.
[0035]
The wiping means 13 slides the wiping cloth against one end of the rotating plate-making roll 1 and scans the wiping cloth from one end to the other end to wipe the plate-making roll 1 and wipe off the cleaning water.
The wiping cloth is a cloth made of polyester of ultra-fine and long fibers or polyester and nylon and having no self-dusting property. A suitable wiping cloth is Savina Minimax (registered trademark), a wiping cloth manufactured by Kanebo Co., Ltd., which is an ultra-fine fiber of 0.1 denier (1 to 5 μmm in thickness) and a long fiber. It is made of polyester and nylon, has a wedge-shaped cross section of the original yarn, takes in dust, and has no self-dusting property. In addition, Toray's wiping cloth is made of ultra-fine long-fiber polyester and has no self-dusting properties.Purchased by Kanebo Co. and Toray Co., Ltd. Can be used.
The configuration of a specific example of the wiping unit 13 is as follows. After wrapping a tape of a wiping cloth fed from a web reel on a rubber roll that comes into contact with the plate-making roll 1, wrap it again on the web reel and the rubber roll, and then wind it on a take-up bobbin. The rotation direction of the rubber roll is opposite to the rotation direction of the plate-making roll 1.
[0036]
The blanket cylinder cleaning means 14 and the impression cylinder cleaning means 15 can have the same structure as the water cleaning means 12, or can be composed of the water cleaning means 12 and the wiping means 13, and employ known means. be able to.
[0037]
The paper dust generation preventing means 17 is for collecting paper dust to be attached to the plate material, and may employ a method such as humidity control, suction by air or electrostatic force, or the like.
[0038]
The printing plate preparation process will be described below.
Image data from a magnetic disk device or the like is provided to an image data calculation control unit 5, which calculates a discharge position of the oil-based ink and a dot area ratio at the position in accordance with the input image data. Do. These operation data are temporarily stored in a buffer. The image data calculation control unit 5 rotates the plate making roll 1 at a predetermined speed, and moves the inkjet nozzle 4a closer to a position close to the plate cylinder 1 by the head separating device. The distance between the inkjet nozzle 4a and the surface of the plate making roll 1 is 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. Dripping.
[0039]
A multi-channel head is used as the inkjet nozzle 4a, and the main scanning is performed by rotating the plate cylinder 1. The ink jet nozzle 4a is continuously moved in the axial direction of the plate cylinder while rotating the plate making roll 1 at a predetermined rotation speed by the image data calculation control unit 5, and the discharge position and the halftone dot obtained by the above calculation are obtained. The oil-based ink is jetted onto the plate-making roll 1 at an area ratio. As a result, a halftone image corresponding to the density of the print document is drawn on the plate making roll 1 with the oil-based ink. In this operation, when an oil-based ink image for one color of a printing original is formed on the plate making roll 1, a plate cylinder = printing plate is completed.
[0040]
Next, in order to protect the inkjet nozzle 4a, the inkjet nozzle 4a is retracted away from a position close to the plate cylinder 1.
[0041]
The printing process after the printing plate is formed is the same as a known lithographic printing method.
Printing ink and fountain solution are applied to the plate copper to form a print image, and the print ink image is transferred onto the blanket cylinder 2 rotating with the plate cylinder, and then the blanket cylinder 2 and the impression cylinder 3 are moved between the blanket cylinder 2 and the impression cylinder 3. By transferring the printing ink image on the blanket cylinder 2 onto the passing printing paper W, printing for one color is performed.
[0042]
After the printing, the solvent cleaning means 10 dissolves and removes the image pattern and the ink receiving area of the oil-based ink remaining on the surface of the plate-making roll 1, and then the electrolytic degreasing means 11 removes the plate copper from the plate-making roll 1. The oil-based ink and the substance forming the ink receiving area firmly adhered to the surface of the paper are peeled off, and then the water washing means 12 sprays tap water passed through a filter onto the plate-making roll 1 and adheres to the plate-making roll 1. The alkaline electrolytic degreasing solution is washed off, and then the wiping means 13 wipes the plate-making roll 1 with a wiping cloth to wipe off the washing water. The desensitizing treatment is performed by the desensitizing means 9 provided as necessary.
[0043]
As described above, a lip-sensitive ink-coated portion of positive information is formed on the chrome-plated satin surface having water-retaining and oil-retaining properties to form a plate cylinder. When the printing is performed after the dampening water is retained in the areas other than the oil-based ink and the dampening water is applied, the oil-based ink adheres to the oil-sensitive ink-coated area, and the oil-based ink image is transferred to the blanket cylinder. Then, printing of one color is performed by transferring the oil-based ink image on the blanket cylinder onto printing paper passing between the blanket cylinder and the impression cylinder. After printing, the chromium-plated matte surface is activated by cleaning with the solvent cleaning means 10, the electrolytic degreasing means 11, the water cleaning means 12, and the wiping means 13 to have a state of having high water-retaining and oil-retaining properties. To restore.
In the case of multi-color printing, the on-press lithographic printing apparatus shown in FIG. 1 is arranged by the number of colors, and plate cylinders separated at each printing station are prepared, and corresponding colors are printed.
[0044]
【The invention's effect】
According to the on-press lithographic printing method and the on-press lithographic printing apparatus of the present invention,
An endless offset plate can be manufactured by simply forming a high-definition ink-coated portion using an inkjet recording device instead of photolithography on an endless plate-making roll, and washing the ink-coated portion with a solvent after printing is completed. As a result, the offset printing machine can be simplified and CTP can be realized because an automatic plate feeding device, an automatic plate discharging device, a plate head / butt holding device, and the like are not required.
[Brief description of the drawings]
FIG. 1 shows an overall configuration diagram of an on-press lithographic printing apparatus for monochrome printing of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Plate roll, 2 ... Blanket cylinder, 3 ... Impression cylinder, W ... Printing web, 4 ... Inkjet recording device, 4a ... Inkjet nozzle, 4b ... Head movement Means 5, image data calculation control unit 6, dampening solution supply device 7, printing ink supply device 8, ink fixing means 9, desensitizing means 10, ..Solvent cleaning means, 11 electrolytic degreasing means, 12 water washing means, 13 wiping means, 14 blanket cylinder cleaning means, 15 impression cylinder cleaning means, 16 ..Paper feeding devices, 17 means for preventing generation of paper dust,

Claims (4)

The chromium plating is applied to the outer peripheral surface of the printing machine, and the surface is roughened.The surface tension is maximized by increasing the surface area. A plate-making roll provided with a matte surface having oil retaining properties is mounted, the surface of the plate-making roll is cleaned and activated, and the ink jet nozzle of the ink jet recording apparatus is brought close to the surface, and the plate making roll and the ink jet nozzle are required. The relative scanning operation is performed to eject ink from an inkjet nozzle based on digital image data to form a positive image ink receiving area on a plate-making roll to form a plate cylinder, and dampening water and oil-based ink are applied to the plate cylinder. The oil-based ink is applied to the ink-receiving area, and the image pattern of the oil-based ink applied to the ink-receiving area is rolled into contact with the plate cylinder to form a blank. Transfer to the printing cylinder, and further transfer the image pattern of the oil-based ink to the printing material passing between the blanket cylinder and the impression cylinder by printing, and after printing, adhere to the surface of the plate-making roll. An on-press lithographic printing method characterized by cleaning the remaining oil-based ink image pattern and ink-receiving area so that they can be reused in the next printing cycle. The cleaning includes a first step of removing an image pattern and an ink receiving area of the oil-based ink remaining on the surface of the plate making roll with a solvent, and a second step of electrolytically degreasing the surface of the roll using the plate making roll as a negative pole. 2. The on-press lithographic printing method according to claim 1, wherein the method is a combination of a step treatment and a third step treatment of washing the roll surface with water. A dampening solution and oil-based ink are supplied to the plate cylinder to apply the oil-based ink to the ink-receiving area formed on the plate cylinder, and the image pattern of the oil-based ink applied to the ink-receiving area rolls and rotates in contact with the plate cylinder. Transfer to the blanket cylinder, transfer the image pattern of the oil-based ink to the printing material that is passed between the blanket cylinder and the impression cylinder and print, and after printing, adhere to the surface of the plate making roll and remain. An on-press lithographic printing apparatus that cleans an image pattern and an ink receiving area of an oil-based ink so that it can be reused in the next printing cycle.
In the plate cylinder, the base material is chrome-plated on the outer peripheral surface, and is further subjected to satin finish.The surface tension is maximized by increasing the surface area, and the surface tension is maximized. It is a plate-making roll with a pear surface having high water retention and oil retention,
An ink jet nozzle is brought close to the plate making roll and a required relative scanning operation is applied to the plate making roll and the ink jet nozzle to eject ink from the ink jet nozzle based on the digital image data to receive a positive image ink on the plate making roll. Equipped with an ink jet printer device that forms an area,
A cleaning means for cleaning the image pattern of the oil-based ink remaining on the surface of the plate making roll and the ink receiving area after printing is completed so that the ink receiving area can be reused in the next printing cycle. Top drawing lithographic printing equipment. The cleaning means includes a solvent cleaning means for removing an image pattern and an ink receiving area of the oil-based ink remaining on the surface of the plate making roll with a solvent as a first step processing, and a negative pressure for the plate making roll as a second step processing. The combination of electrolytic degreasing means for immersing in an alkaline degreasing solution as an electrode and electrolytically degreasing the roll surface and water washing means for washing the roll surface with water as a third step treatment [Claim 3]. On-machine drawing lithographic printing equipment.

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