JP2004066566A - Gravure platemaking method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gravure platemaking method, in which a gravure plate produced by adding screen ruling to an FM (frequency modulation) screen applicable to an offset printing or the like with an inkjet printer in place of a photo lithography is easily, quickly and favorably obtained without developing pin hole. <P>SOLUTION: By rotating a roll to be made up, the tape of a wiping cloth is drawn out of a raw cloth reel so as to wipe off smudges and oils and fats adhering to the roll to be made up. A negative mask is coated by jetting ink having resistance to etching liquid from an inkjet nozzle on the basis of digital plate information, which is formed by piling up the digital information of the FM screen obtained by FM screening so as to realize the necessary size for the favorable transferring of ink to the minimum small cell on a plate information to the digital information made only of the screen ruling of the most shadowy part of the gravure plate of an AM screen through the scanning action of the inkjet nozzle after or in succession to the wiping-off by the tape. After the formation of the negative mask, cells are formed by etching. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a simple and easy method of obtaining a gravure plate obtained by adding a screen line to an FM screen (Frequency Modulation Screen) applicable to offset printing or the like using an inkjet printer instead of photolithography, and having no pinholes. The present invention relates to a gravure plate making method which can be favorably manufactured.
[0002]
[Prior art]
Conventionally, the gravure plate making method used in practice is to apply a photosensitive film on a plate making roll, form a latent image by laser exposure, develop it to form a resist mask, and etch the exposed surface of thick copper sulfate plating. There is a photolithography method in which a cell is formed, a resist image is removed, and finally chromium plating is performed, and an engraving method in which a cell is engraved on a plate making roll by an electronic engraving machine and chromium plating is performed.
A major problem in the photolithography method is how to avoid generation of pinholes when a photosensitive film is applied and formed. The cause is dirt or grease adhering to the plate making roll. In addition, there is a problem that if the compatibility between the photosensitive agent and the developing solution is poor, a good plate cannot be formed, and a problem that an alkaline developing solution and a resist stripping solution containing the photosensitive agent is discharged to pollute the global environment.
[0003]
Both the photolithography method and the engraving method were AM screens.
FIG. 6 shows a normal gravure version of an AM screen (Amplitude Modulation Screen). In the gravure plate, the gradation expression is represented by the size of a halftone dot, and it is necessary to put the ink into a cell with a doctor and scrape off excess ink, so that the area of the screen line at the shadow portion becomes 20% to 30%. That is, the gravure plate is configured as a plate that expresses the gradation of the printed matter at about 0 to 75% with respect to the gradation of the printed matter of 0 to 100%.
The gravure plate includes a method of forming cells by engraving and a method of forming cells by applying, exposing, developing, and etching a photosensitive film (hereinafter, referred to as an etching method). Since it is formed in the shape of a pyramid, the transfer of the ink in the highlight portion is good. In the etching method, since the cells are formed in shallow dish-shaped concave portions, the transfer of the ink is inferior to the engraving method due to the ink being clogged in the cells in the highlight portion where the cells are very small. On the other hand, there is an advantage that the ink can be reliably transferred to the intersection by cutting off the intersection of the screen lines of the uppermost shadow portion so that the ink flows, and the outline of the character can be made an outline without jagged. Since the cells in the shadow area are also shallow, they are suitable for printing using water-based ink.
[0004]
[Problems to be solved by the invention]
Therefore, it is desired to improve the transferability of the ink in the highlight portion where the cell is very small in the etching method.
[0005]
FIG. 7 shows an AM screen of an offset printing plate or a flexographic printing plate. An AM screen such as an offset printing plate also expresses the gradation expression by the size of a halftone dot, but unlike a gravure plate, it does not require a screen line, so the gradation of the printed material is approximately 0 to 100% and the gradation of the plate is approximately 100% accurate. It corresponds to.
[0006]
In recent years, in the field of offset printing and flexographic printing, the FM screen method in which the gradation expression is represented by the number of small halftone dots as shown in FIGS. It is beginning to be put to practical use mainly. Since the FM screen technology can obtain the resolution of the minimum drawing dot that uses the fine structure expression power, the image quality is expected to be improved even in the output from a low-resolution output device such as a printer or an on-demand printer. In gravure printing, there has been no attempt to apply the gravure printing because there is no screen line for putting ink into a cell with a doctor and scraping off excess ink.
[0007]
The following is an excerpt of the advantages of the FM screen method applied in the fields of offset printing and flexographic printing, which are published on the Internet by the Japan Printing Industry Federation.
(1) Since the FM screen is not regularly arranged in a halftone dot shape unlike the screen (FIG. 7), it is possible to avoid occurrence of moiré which may be an obstacle. In the AM screen, the screen angle is set for each plate so that the output moire is minimized. However, in the FM screen, the output moire does not occur because dots are scattered. The FM screen does not generate a rosette pattern. On the AM screen, a pattern of a turtle pattern appears from the highlight to the middle, but this does not occur on the FM screen. No line break occurs even when printing five or more colors.
(2) The FM screen can reduce the halftone dot size over all gradations from highlight to shadow, so that high-resolution print reproduction can be performed. The screen is distributed without the minimum dots sticking up to about 30% density.
(3) Density jumps are not noticeable on FM screens. Density jumps (steps in density) occurring at halftone dots near 50% on the AM screen are inconspicuous on the FM screen. This is because the halftone dots near the middle of the screen make random contact with the adjacent points, so that the density step is reduced.
(4) The color tone of the FM screen is vividly expressed. Colors close to the primary colors and colors with high saturation can be reproduced with the four process colors, and a more realistic expression effect can be exhibited.
(5) The FM screen can have a higher resolution than the screen with the same output data capacity. Since the interval between the halftone dots can be reduced, if the output data capacity is the same, the resolution can be made higher than that of the AM screen by reducing the dot diameter. Since the minimum drawing dot has a physical resolution in the FM screen, it can be expected that image data (32 to 51% of the screen) is smaller than that of the screen. Since the dot diameter can be increased to obtain the same resolution as that of the 175-line AM screen, the FM screen created from the same input data amount requires a relatively small image data amount. For this reason, if the quality equivalent to the screen of 175 lines can be realized with an FM screen having a large dot diameter, the processing time and waiting time of the plate making / outputting step can be reduced, and the productivity can be improved.
(6) In the FM screen, the minimum drawing dot becomes the physical resolution, and it is easier to obtain a higher resolution than the AM screen. As for the number of gradations, the number of gradations decreases at a high screen line number in order to realize high definition on an AM screen, but the FM screen does not have such a case.
(7) The tone of the middle to shadow parts of the FM printed matter is higher than that of the AM printed matter, and the highlight to the middle part is almost equal to or lower than AM. The FM value of the K value representing the contrast on the shadow side is generally small. Regarding the ink solid density, in a high definition FM screen using a small dot diameter, it is difficult to obtain a high density in a halftone portion similarly to an AM screen having a high screen ruling.
(8) Like the high screen ruling, the highlight expressive power of the FM screen is disadvantageous because it is easily affected by dampening water in film output, plate printing, offset lithographic printing, and the like. In forming a calibration image, FM screens theoretically have more adaptation means than high screen ruling AM screens.
(9) In order to use FM screens for high-quality printing, quality control does not succeed at the standard AM screen 175 line level, and quality control of plate making and printing using FM screens is completed only after strictly controlling the management level. To do it.
[0008]
With the engraving method, it is impossible to engrave an FM screen, but with the photolithography method there is a possibility. However, the photolithography method requires many processing steps, requires large facilities and is expensive, and has many problems such as deterioration of a photosensitive solution and a developing solution and discharge of an alkaline waste solution.
[0009]
On the other hand, in the ink jet printer technology, since the ejection of 1 picoliter has become possible, it has begun to attract attention as a technology replacing photolithography. One picoliter is the volume of a cube having a side of 1 μm.
[0010]
The invention of the present application has been made in view of the above-described points. By adding a screen line to an FM screen applicable to offset printing or the like, the cell of a gravure AM screen formed by an etching method has a very large cell. Overcoming the drawbacks of poor ink transfer due to the clogging of the cells in the small highlight area, and the intersection of the screen line at the shadow end, where the ink flows, is cut off at the intersection. The transfer of ink can be ensured and the outline of the character can be made outline without jaggedness.The cells in the shadow area are shallow, making it suitable for printing using water-based ink. The advantage of FM screens over AM screens in halftone areas is that It offers the advantages of being able to print lines of 5 colors or more without line breaks, high-resolution print reproduction, and inconspicuous density jumps. It is an object of the present invention to provide a gravure plate making method which can shorten the time and can reduce or avoid problems such as discharge of an alkaline waste solution of a photosensitive solution and a developing solution.
[0011]
[Means for Solving the Problems]
The invention described in [Claim 1] is that the plate making roll is chucked at both ends, an ink jet nozzle of an ink jet printer is brought close to the plate making roll, and a relative scanning operation is performed between the ink jet nozzle and the plate making roll. The digital information of the FM screen obtained by performing the FM screening so that the minimum cell has a required size for good ink transfer with respect to the plate information before forming the plate, and the minimum information of the gravure plate of the AM screen. Based on digital version information obtained by superimposing digital information only on the screen portion of the shadow portion, a negative mask is formed by spraying ink having resistance to an etching solution from an inkjet nozzle onto a plate-making roll, and then, It is characterized by forming cells by etching the exposed metal surface of the plate making roll Gravure plate-making method that is intended to provide.
According to a second aspect of the present invention, the plate making roll is chucked at both ends and rotated, and the tape of the wiping cloth is fed out from the raw material reel, and is slid into contact with one end of the plate making roll to take up the tape. To the other end of the plate-making roll, wipe the dirt and oils and fats adhered to the plate-making roll with tape, and set the ink jet nozzle of the ink jet printer so as to follow the wiping or after the wiping. Scanning operation is performed relative to the inkjet nozzle and the plate-making roll in close proximity to the plate-making roll, so that the minimum number of cells for the plate information before the plate is formed can transfer ink well. Digital information of the FM screen obtained by performing the FM screening and a digital image of only the screen line of the shadow portion of the gravure version of the AM screen. Based on the digital version information obtained by superimposing the information, the inkjet nozzle sprays an ink having resistance to the etching solution onto the plate making roll to form a negative mask, and then, exposes the exposed metal surface of the plate making roll To form a cell by etching a gravure plate.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
In the gravure plate making method according to the embodiment, the plate making roll is chucked at both ends and rotated, the wiping cloth tape is fed out from the raw fabric reel, slid into contact with one end of the plate making roll, wound up, and the tape sliding contact position is set. Move to the other end of the plate making roll, wipe the dirt and oils and fats and oils adhered to the plate making roll with tape, and set the ink jet nozzle of the ink jet printer device to the plate making so as to follow after or after wiping. By performing a relative scanning operation between the ink jet nozzle and the plate-making roll in close proximity to the roll, the minimum number of cells for the plate information before forming the plate is a required size that allows good ink transfer. Information of the FM screen obtained by performing the FM screening as described above, and the data of only the screen line at the most shadow part of the gravure version of the AM screen. Based on the digital plate information obtained by superimposing the metal plate information, the inkjet nozzle sprays ink having resistance to the etching solution onto the plate making roll to apply and form a negative mask, and then exposes the exposed metal of the plate making roll The surface is etched to form a cell, then the resist is stripped off and hard chromium plating is provided.
Specifically, the minimum cell size at which the ink transfer is favorably performed is about 15 μm square.
[0013]
An embodiment of the gravure plate making method of the present invention will be described with reference to the drawings.
FIG. 1 is a front view of a plate-making ink jet printer for carrying out the gravure plate-making method of the present invention.
FIG. 2 is an enlarged side view of a main part before starting the operation of the wiping head.
FIG. 3 is an enlarged side view of a main part of the cleaning head during operation.
In FIG. 1, a casing denoted by reference numeral 1 has a roll feed-in / out opening 1a at the upper part on the front surface and a roll feed-out door 2 which rises to close the roll feed-in / out opening 1a.
A plate making roll chuck rotating means 3 is provided in the casing 1. The plate-making roll chuck rotating means 3 rotates the plate-making roll R with a drive-side chuck 3a, which is rotationally driven by a motor (not shown), and moves on the movable table 3b in accordance with the roll length and with the tail chuck 3c. The rotation speed at which the required low speed, for example, the peripheral speed becomes 0.5 m / s, is calculated based on the input of the diameter of the plate making roll R that can be chucked, and the roll is rotated at the rotation speed.
The plate making roll R according to this embodiment is a sleeve type plate making roll for gravure printing having a size of 100 mm x 800 mm to 300 mm x 2000 mm.
The movable table 3b is configured such that the movable table 3b is guided by a horizontal linear guide 3d provided on the rear wall of the casing 1 and a ball screw 3e provided between the linear guides 3d. A ball nut 3f to be screwed is provided on the movable table 3b, and the ball screw 3e is rotated by a servomotor 3g, so that the ball nut 3f becomes a runner.
[0014]
Below the plate making roll R chucked by the plate making roll chuck rotating means 3, a moving table 5 mounted on a rail 4 can reciprocate along the plate making roll R by driving a ball screw. A movable bracket 7 is provided on an elevating table 6 mounted on the moving table 5, and the movable bracket 7 is equipped with a wiping head.
In the configuration for raising and lowering the lifting table 6, the lifting table 6 is guided by a vertical linear motion guide 8 provided on the moving table 5, and a ball screw (not shown) is on the vertical axis of the moving table 5. And a ball nut (not shown) screwed to the ball screw is provided on the lifting table 6, and the ball screw is rotated by a servo motor (not shown) so that the ball nut becomes a runner.
The movable bracket 7 is configured to further move up and down with respect to the elevating table 6 that performs the above-described elevating. In the configuration in which the movable bracket 7 is raised and lowered, a male guide 10 provided on the movable bracket 7 is guided by a female guide 9 provided on the lifting table 6, and the lifting table 6 and the movable bracket 7 are connected by the cylinder device 11. The movable bracket 7 is connected to and moved up and down with respect to the elevating table 6 by expansion and contraction of the cylinder device 11.
The movable bracket 7 is raised before the elevating table 6 by the extension operation of the cylinder device 11, and is then chucked by the plate making roll chuck rotating means 3 when the elevating table 6 is moved up and down. And a bay portion 7a for receiving the plate-making roll R.
The proximity sensor 12 is attached to the movable bracket 7 so as to correspond to the center of the bay 7a. The proximity sensor 12 outputs a detection signal when the gap with the lower surface of the plate making roll R received in the bay portion 7a becomes, for example, 3 mm. Based on the detection signal, the lifting table 6 stops lifting. It is supposed to. Accordingly, the movable bracket 7 is moved upward by a large stroke by the extension of the cylinder device 11, and then the movable bracket 7 is moved to the maximum in the bay 7a of the movable bracket 7 regardless of the diameter of the plate making roll R. A stroke corresponding to the diameter of the plate making roll R is shared by the elevating table 6, thereby shortening the operation time and shortening the positioning stroke.
The moving speed of the moving table 5 is changed according to the number of rotations of the plate making roll R so that the plate making roll R moves by, for example, 8 to 10 mm when it makes one rotation.
[0015]
The wiping head draws out a tape T of a wiping cloth having no self-dusting property from a web reel 13 attached to the movable bracket 7 and a pair of guide rolls 14 provided on an opposing portion sandwiching the bay portion 7a of the movable bracket 7, 15, the tape T is wound around a winding bobbin 17 driven to rotate by a first torque motor 16, and a braking free roll 21 to which a nip pressure is applied to a guide roll 14 by a cylinder device 20. The tape T is pressed and pressed, and the rotation of the guide roll 14 is braked to apply a brake to the feeding of the tape T from the material reel 13.
The braking free roll 21 has play in the shaft and the bearing so as to be separated from the guide roll 14 by, for example, 0.5 mm, and the braking free roll 21 is urged by the cylinder device 20 being extended, and the braking free roll 21 is urged. Reference numeral 21 applies a nip pressure to the guide roll 14.
The plate making roll chuck rotating means 3 rotates the plate making roll R in a direction opposite to a running direction of the tape T unwound from the raw material reel 13 so that a load is applied to the first torque motor 16. I have.
[0016]
The rewinder shaft 18 is configured so as to be connected to and disengaged from the output shaft of the second torque motor 19, to be able to be pulled out and removed in the axial direction, and to insert and support the center hole of the material reel 13. The second torque motor 19 has a smaller torque than the first torque motor 16 and is provided so as to rotate in a direction in which the feeding of the tape T from the raw reel 13 is braked.
Since the tape T is fed out from the material reel 13 by the first torque motor 16, the second torque motor 19 rotates the creep in a direction opposite to the rotational direction in which the tape T is driven, thereby causing the tape T to rotate. Braking can be applied to the payout. Accordingly, the application of braking to the feeding of the tape T is performed by pressing the guide roll 14 with the braking free roll 21 to which the nip pressure is applied by the cylinder device 20 and the second torque motor 19 synergistically.
[0017]
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 μm 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, a wiping cloth manufactured by Toray Industries, Inc. is a cloth made of polyester of ultra-fine long fibers and having no self-dusting property, and is applicable.
The material reel 13 is formed by winding a wiping cloth tape T around a bobbin, and can be purchased and used from Kanebo Corporation or Toray Industries, Inc.
[0018]
On the upper side of the plate making roll R chucked by the plate making roll chuck rotating means 3, a printer head 22 having an ink jet nozzle 22a opposed to the plate making roll R is provided, and the plate making roll on which the ink jet nozzle 22a is rotated. An ink having a resistance to an etching solution is ejected by moving close to one end of R, and moves to the other end of the plate making roll R to form an image.
The movement of the printer head 22 toward and away from the plate-making roll R is performed by raising and lowering a lifting table 24 supporting the printer head 22 via a bracket 25 by lifting driving means mounted on the carriage 23. .
The elevating / lowering driving means is such that a ball screw provided on the carriage 23 and a ball nut fixed to the elevating table 24 are screwed together, and when the ball screw is driven by the servo motor 29, the ball nut becomes a runner. It is done in.
The reciprocating movement of the printer head 22 along the plate-making roll R is performed by reciprocating the carriage 23 by reciprocating drive means.
The reciprocating drive means includes a ball screw 27 in which a carriage 23 is engaged and guided by a linear motion guide 26 mounted on a rear wall of the casing 1 and a ball screw 27 supported on the rear wall of the casing 1 and a ball fixed to a lifting table 24. When the ball screw 27 is driven by the servomotor 28 when the nut is screwed, the ball nut becomes a runner.
[0019]
The operation will be described.
First, wiping is performed from one end to the other end of the plate-making roll R on which the wiping head is rotated, and then ink is ejected from the ink jet nozzle 21 of the printer head 22 to the rotated plate-making roll R. A corrosion resistant image is formed.
[0020]
The operation of the wiping head will be described in detail.
The raw material reel 13 is attached, and the tape T of the wiping cloth is wound around the free roll 21 for braking, is wound around the guide rolls 14 and 15, and the tape feeding end is wound around the winding bobbin 17.
The plate making roll chuck rotating means 3 chucks and rotates the plate making roll R at both ends. The rotation speed at this time may be a relatively low rotation speed, and is not limited to a specific rotation speed. Next, the movable table 5 moves to a position corresponding to one end of the plate making roll R.
The movable bracket 7 is raised with respect to the elevating table 6 by extending the cylinder device 11, and then the elevating table 6 is moved up, and the plate-making roll R relatively enters the bay portion 7 a of the movable bracket 7 to make the plate-making plate. When the gap with the lower surface of the roll R becomes, for example, 3 mm, the proximity sensor 12 outputs a detection signal and the lifting table 6 stops rising.
At substantially the same time when the lifting table 6 is raised, the first torque motor 16 and the second torque motor 19 are driven, the cylinder device 20 is extended, tension is applied to the tape T of the wiping cloth, and tape running starts.
When the elevating table 6 rises, the plate-making roll R comes into contact with the tape T wrapped around the guide rolls 14 and 15 and relatively enters the bay portion 7a of the movable bracket 7, so that the tape T is rolled. To slide along the peripheral surface of. The rotation of the plate making roll R is in a direction opposite to the running direction of the tape T. Accordingly, the tape T slides and travels on the rotating plate-making roll R without loosening the tension, and starts wiping of dirt and oils and fats adhered to the plate-making roll R.
The moving table 5 moves from a position corresponding to one end of the plate making roll R to a position corresponding to the other end after a lapse of several seconds after the lifting table 6 stops moving up. Accordingly, the wiping cloth is wiped with the tape T from one end to the other end of the plate making roll R. Next, after the elevating table 6 is lowered and returned, the cylinder device 11 is reduced and the movable bracket 7 is lowered with respect to the elevating table 6, and the tape T wrapped around the guide rolls 14 and 15 is separated from the plate making roll R. When returning to the state of being stretched horizontally, the first torque motor 16 and the second torque motor 19 are stopped, the cylinder device 20 is reduced, the tape running is stopped, and the moving table 5 is moved to the original position. Move back to.
[0021]
Next, drawing an image on the plate making roll R rotated by ejecting ink from the ink jet nozzle 21 of the printer head 22 will be described in detail.
The carriage 23 is moved by the drive of the servo motor 28, and the ink jet nozzle 21 comes to a position corresponding to one end of the plate making roll R, and the carriage 23 is stopped. The elevation table 24 is lowered by the drive of the servomotor 29, the ink jet nozzle 21 approaches the plate-making roll R, and the elevation table 24 is stopped.
Ink is ejected from the ink jet nozzle 21 to the rotated plate-making roll R, and the carriage 23 is moved by the driving of the servo motor 28, so that the ink-jet nozzle 21 moves to the other end of the plate-making roll R. Draw an image. After wiping with the wiping cloth, ink is ejected to describe the plate information, so that pinholes do not occur.
When the drawing of the image is completed, the elevation table 24 is lifted and returned by the driving of the servomotor 29, and the ink jet nozzle 21 is separated from the plate making roll R. Next, the carriage 23 is returned and moved by the driving of the servo motor 28, the printer head 22 is returned to the standby position, and the carriage 23 is stopped.
[0022]
A plate making roll R for gravure printing is chucked at both ends by plate making roll chuck rotating means 3, and an ink tank of a cartridge storing ink having resistance to a corrosive liquid corroding thick copper sulfate plating is set. A negative mask is formed on the plate making roll by the ink jet nozzle 21 and is burned.
The gravure plate making is completed by performing etching on a plate making roll on which a negative mask is formed, forming cells, stripping the resist, and performing chrome plating.
[0023]
Even if the diameter of the plate making roll R is variously varied, the peripheral surface speed of the plate making roll R chucked at both ends by the plate making roll chuck rotating means 3 is adjusted to the linear forming speed of the ink jetted from the ink jet nozzle 21. In addition, in response to the rotation speed being different due to variously different diameters of the plate making roll R, the moving speed of the ink jet nozzle 21 along the plate making roll R is changed so that the diameter of the plate making roll R becomes various. , The overlap of the pixels is the same.
[0024]
In the gravure plate making method of the present invention, the thick copper sulfate plating on the surface of the plate making roll R is mirror-finished, and the negative plate information is formed on the roll surface with an ink which is resistant to an etching solution by inkjet and has high adhesion. It is preferably formed.
However, the plate-making roll R may be a mirror-finished surface whose surface is nickel-plated, chrome-plated, or zinc-plated.
At this time, since an etching solution corresponding to the plating is selected, an ink for inkjet having a resistance and an adhesive force corresponding to the etching solution is selected.
When etching is performed by forming a negative plate information by ink jetting by thick chrome plating and leaving chrome plating at the bottom of the cell, subsequent chrome plating is not required.
When zinc plating is applied to the thick copper sulfate plating surface or nickel plating surface and mirror-polished, then negative plate information is formed by ink jet, etching is performed and then chrome plating is performed. The chromium plating can be dissolved and removed together with a hydrochloric acid solution, and if zinc plating and mirror plating are used, negative plate information can be formed by ink jet. This is simpler than ballad plating removal and plate drop polishing.
[0025]
In particular, the invention of the present application is to form a negative mask by performing a relative scanning operation between an inkjet nozzle and a plate making roll, and jetting ink having resistance to an etchant from the inkjet nozzle to the plate making roll. ,
The digital information of the FM screen obtained by performing the FM screening so that the minimum cell has a required size for good ink transfer with respect to the plate information before forming the plate, and the minimum information of the gravure plate of the AM screen. A negative mask is applied and formed on the basis of digital version information obtained by superimposing digital information on only the screen portion of the shadow portion.
The specific contents of the digital version information will be described below with reference to the drawings.
[0026]
Embodiment 1
In FIG. 4, A1 represents digital information of an FM screen obtained by performing an FM screening using an FM screening program when a gradation of 0% to 100% is prepared as plate information before forming a plate. It is. B1 indicates digital information of only the screen line of the shadow portion of the gravure plate of the AM screen, regardless of the plate information before the plate is formed. C2 displays digital version information in which digital information of the FM screen shown in A1 and digital information of only the screen lines of the AM screen shown in B1 are superimposed.
[0027]
Embodiment 2
In FIG. 5, A2 is an FM screen obtained by performing an FM screening using an FM screening program different from that in Example 1 when a gradation of 0% to 100% is prepared as plate information before forming a plate. Is displayed. B2 displays digital information of only the screen line of the shadow portion of the gravure plate of the AM screen, irrespective of the plate information before the plate is formed. C2 displays digital version information in which digital information of the FM screen shown in A2 and digital information of only the screen lines of the AM screen shown in B2 are superimposed.
[0028]
Digital version information indicated by C2 in FIG. 5 was created for three colors of Y, M, and C.
In this case, assuming that the minimum cell has a required size for good ink transfer, a laser exposure device manufactured by Cleopatex Co., Ltd. of Canada is used to arrange four laser beams of 7 μm square in the vertical and horizontal directions, one on each side. Numerical input required for the FM screening program so that a laser beam forming a square cell having a diameter of 28 μm can be output as a unit and correspondingly, the minimum cell is a square and one side is 28 μm. Was performed to perform FM screening on the plate information before forming the plate to obtain digital information on the FM screen.
Then, based on the digital color plate information of one color, the surface on which the positive type photosensitive film is formed is exposed and alkali-developed, and then the exposed metal surface (copper-plated surface) is treated with a cupric chloride solution. After etching, the resist was stripped off with a strong alkaline solution, and then a gravure plate having hard chromium plating was prepared for three colors and mounted on a gravure rotary printing machine to perform overprinting. The jump was not noticeable. High-resolution print reproduction was achieved. Drying load was small and drying was performed smoothly. The outline of the character could be made an outline without jaggedness.
[0029]
In the present invention, either a positive type or a negative type photosensitive film may be used.
[0030]
【The invention's effect】
As described above, the gravure plate making method of the present invention has the following effects.
[0031]
According to the gravure plate making method of the first aspect, since a negative mask is formed on a plate making roll by an ink jet printer technique, the conventional photosensitive film coating, laser exposure and development steps can be omitted in one step, and the photosensitive film Problems such as poor adhesion, poor compatibility between the photosensitive film and the developer, and deterioration of the developer can be avoided, high reliability for gravure plate making can be secured, plate making time can be significantly reduced, and plate making line space can be significantly reduced. The connection system can be constructed inexpensively, the plate making process can be shortened, and problems such as discharge of alkaline waste solution of the photosensitive solution and the developing solution can be reduced or avoided.
[0032]
According to the gravure plate making method described in [Claim 2], before forming a negative mask on the plate making roll, dirt and oils and fats adhering to the plate making roll are wiped off with a wiping cloth, and the plate making is performed by an inkjet printer technique. Since a negative mask is formed on the roll, the ink ejected from the ink jet nozzles of the printer head can be reliably applied to the plate making roll, and the pinhole, that is, the point where the ink is not applied to the portion where the ink is to be applied, is provided. Since generation can be avoided with an extremely high probability, and good pixels can be formed on the plate making roll, the plate can be applied to the production of gravure plates, which are plate making rolls having various diameters, and the conventional photosensitive film coating and Laser exposure and development steps can be omitted in one step, and a good negative mask without pinholes It can be formed quickly and easily, while the conventional photosensitive film coating, laser exposure and developing steps can be omitted in one step, and the adhesion of the photosensitive film, poor compatibility between the photosensitive film and the developing solution, deterioration of the developing solution, etc. Problem can be avoided, high reliability for gravure plate making can be secured, and plate making time can be greatly reduced, leading to significant reduction in plate making line space.
[0033]
The invention described in [Claim 1] or [Claim 2] provides a gravure AM screen formed by an etching method by adding a screen line to an FM screen applicable to offset printing or the like. Overcoming the drawbacks of poor ink transfer due to clogging of the cells in the highlight area where the cells are very small, and lacking the flow of ink at the intersection of the screen lines in the shadow area. In addition to the advantages that the ink can be transferred to the intersection part without fail and the outline of the character can be made an outline without jaggedness, and the cells of the shadow area are shallow, so that it is suitable for printing using water-based ink. The advantage that the FM screen is superior to the AM screen in the highlight area to the halftone area is Can be avoided raw, that does not occur missing line in the printing of five or more colors, that can be printed reproduction of high resolution, you can enjoy the benefits of such that den City jump is inconspicuous.
[0034]
Since the smallest cell is of a required size for good ink transfer, the ink is clogged in the cell in a very small highlight portion of the gravure AM screen formed by the etching method. It is possible to overcome the conventional disadvantage that the transfer of the ink caused by the above-mentioned problem is poor.
The intersection of the AM screen line at the shadow area can be a free flow cell that lacks ink so that ink flows, and the ink can transfer to the intersection reliably and the outline of the character can be an outline without jagged edges. In addition, since the cell at the outermost shadow portion is shallow, it can continue to enjoy the conventional advantage that it is suitable for printing using water-based ink. In addition, the advantages of the screen that can be enjoyed by offset printing or the like can also be enjoyed by the gravure version.
The advantages of the FM screen from the highlight part to the halftone part are better than that of the AM screen, such as avoiding moiré, preventing line breaks even when printing five or more colors, and enabling high-resolution print reproduction. Benefits such as inconspicuous city jumps can be enjoyed.
Since a conventional large cell is formed by being divided into a plurality of minimum cells, the ink film thickness is reduced, the drying load is reduced, and higher-speed printing is possible.
[Brief description of the drawings]
FIG. 1 is a front view of a plate-making ink jet printer for carrying out a gravure plate-making method of the present invention.
FIG. 2 is an enlarged side view of a main part before the operation of the cleaning head is started.
FIG. 3 is an enlarged side view of a main part of the cleaning head during operation.
FIG. 4 relates to the gravure plate making method of the present invention, and is intended to explain obtaining digital version information C1 by superimposing digital information A1 of an FM screen and digital information B1 of only a screen line of a gravure AM screen. FIG.
FIG. 5 relates to the gravure plate making method of the present invention, in which digital information A2 of the FM screen and digital information B2 of only the screen lines of the gravure AM screen are superimposed to obtain digital plate information C2. FIG.
FIG. 6 is a diagram showing a conventional gravure plate normal AM screen.
FIG. 7 is a diagram showing a normal AM screen used for conventional offset printing and the like.
FIG. 8 is a diagram showing an FM screen used for conventional offset printing or the like.
FIG. 9 is a view showing another FM screen used for conventional offset printing and the like.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Casing, 1a ... Roll-in / out opening, 1b ... Roll-in / out opening, 2 ... Roll-out / door, 3 ... Plate-making roll chuck rotating means, 3a ... Drive side Chuck, 3b: movable table, 3c: tail chuck, R: plate roll, 3d: linear guide, 3e: ball screw, 3f: ball nut, 3g ... Movable table, 4 ... Rail, 5 ... Movable table, 6 ... Elevating table, 7 ... Movable bracket, 7a ... Bay portion, 8 ... Linear guide, 9 ... Female Guide: 10: Male guide, 11: Cylinder device, 12: Proximity sensor, 13: Raw reel, T: Wiping cloth tape, 14, 15: Guide roll, 16 ... First torque motor, 17 ... Stripping bobbin, 18 rewinder shaft, 19 second torque motor, 20 cylinder device, 21 free roll for braking, 22 printer head, 22a inkjet nozzle , 23 ... carriage, 24 ... elevation table, 25 ... bracket, 26 ... linear guide, 27 ... ball screw, 28 ... servo motor, 29 ... servo motor,

Claims (2)

The plate making roll is chucked at both ends, the ink jet nozzle of the ink jet printer is brought close to the plate making roll, and the inkjet nozzle and the plate making roll perform a relative scanning operation, and the plate information before forming the plate is obtained. The digital information of the FM screen obtained by performing the FM screening so that the minimum cell has a required size for the good transfer of the ink and the digital information of only the screen line of the shadow portion of the gravure plate of the AM screen are obtained. Based on the digital plate information that is superimposed, an ink having a resistance to the etching liquid is jetted from the inkjet nozzle to the plate making roll to form a negative mask, and then the exposed metal surface of the plate making roll is etched. A gravure plate-making method characterized by forming cells by heating. The plate-making roll is chucked at both ends and rotated, and the tape of the wiping cloth is drawn out from the raw material reel, slid into contact with one end of the plate-making roll and wound up, and the sliding position of the tape is moved to the other end of the plate-making roll. Wipe off dirt and oils and fats adhered to the plate making roll with tape, and bring the ink jet nozzle of the ink jet printer device close to the plate making roll so that the ink jet nozzle is covered with the ink jet nozzle so as to follow the wiping or after the wiping. It is obtained by making the plate-making roll perform a relative scanning operation and performing an FM screening so that the minimum number of cells for the plate information before forming the plate is a required size for good ink transfer. A digital image obtained by superimposing digital information of the FM screen and digital information of only the screen line at the shadow portion of the gravure version of the AM screen. Based on the plate information, the inkjet nozzle sprays ink having resistance to the etchant from the inkjet nozzle onto the plate-making roll to form a negative mask, and then forms a cell by etching the exposed metal surface of the plate-making roll. A gravure plate making method.

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