JP2007219093A - Processing method of planographic printing plate and automatic developing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic developing apparatus that can develop a planographic printing plate having a photopolymerizable photosensitive layer which uses a high-definition screen upon image exposure, for a long period of time without inducing an image defect such as process irregularity. <P>SOLUTION: The processing method of a photosensitive planographic printing plate and the automatic developing apparatus include steps of scanning exposure of a photosensitive planographic printing plate having a photopolymerizable photosensitive layer on a support with laser light and carrying the plate to a developing unit 10 to develop, wherein developing brush rollers 141, 142 as a rubbing member are rotated in an opposite direction to the developing direction while the developing process is not carried out. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a processing method and an automatic developing device for a lithographic printing plate in which a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer on a support is scanned and exposed by a laser and then conveyed to a development processing unit for development.

  In recent years, the development of lasers has been remarkable, and high-power and small-sized lasers have become readily available. These lasers are very useful as a recording light source when directly making a printing plate from digital data of a computer or the like.

  Ar ion laser (488 nm) or FD-YAG laser (532 nm) is used as a recording light source, and a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer suitable for these light sources has been developed and put into practical use. . Recently, an InGaN-based semiconductor laser (violet laser, 350 nm to 450 nm) has been developed, and a bright room, lower cost of the exposure machine, and higher productivity are expected. The development of lithographic printing plates having a polymerizable photosensitive layer has been accelerated.

  Furthermore, in the plate making / printing industry, various screening printing with high definition can be put into practical use relatively easily due to the combination of the above-mentioned technology that outputs halftone dots directly from data to plate making and the screening processing software. Therefore, high-definition screens are widely used in combination with high-end printing orientation in the market. As high-definition screens, conventional AM screens include a screening method that exceeds 250 lines, an FM type, and an AM / FM hybrid type (see Non-Patent Document 1).

  Further, in order to form a lithographic printing plate, development processing is performed after recording on the printing plate by laser exposure. In general, an automatic developing device is used for developing a printing plate. As an automatic developing device, a device including steps including heating, pre-water washing, development, water washing, and finishing is widely used (see Patent Document 1).

Journal of the Japan Printing Society, Volume 40, Issue 2 (2003) JP 2003-107728 A

  However, when a printing plate on which an image has been recorded by laser exposure using a high-definition screen is developed, uneven processing due to the developing brush may occur, resulting in image defects.

  The present invention has been made based on the background as described above, and develops a lithographic printing plate having a photopolymerizable photosensitive layer using a high-definition screen in image exposure for a long period without causing image defects such as processing unevenness. An object of the present invention is to provide a processing method and an automatic developing apparatus for a lithographic printing plate that can be processed.

  As a result of intensive studies, the present inventors have found the following matters. The halftone dot portion of a lithographic printing plate having a photopolymerizable photosensitive layer that uses a high-definition screen for image exposure has a larger or smaller halftone dot number than the halftone dot portion of an AM screen of about 175 lines that has been conventionally used. Therefore, since the perimeter of the halftone dots per unit area (the boundary length between the image portion and the non-image portion) is long, there are many portions called fringes. The fringe portion is a boundary between the portion to be developed and the remaining portion, and therefore contains some insoluble matter that is not dissolved or dispersed in the developer. For this reason, it has been found that the insoluble portion of the boundary portion, which has not been a problem in the conventional screen size AM screen, is likely to be uneven in processing on the high-definition screen, resulting in image defects.

  In addition, as shown in FIG. 14, when a large lithographic printing plate is processed after developing a large number of small (small) lithographic printing plates, the portion where the small lithographic printing plate is processed It was found that the halftone dot density was higher in the place corresponding to, and processing unevenness occurred. For example, when a planographic printing plate having a width direction of 650 mm and a longitudinal direction of 550 mm is continuously processed, and then a planographic printing plate having a width direction of 1030 mm and a longitudinal direction of 800 mm is processed, it is placed at a place corresponding to the first processed width direction of 650 mm. Uneven processing occurs.

  In addition, when the present inventor continues to process a large number of printing plates of the same size, as shown in FIG. It was found that processing irregularities occur because of a slight weakening.

  As a result of further intensive studies, the present inventor has found that when the rubbing member is rotated in the direction opposite to the direction of the development processing while the development processing is not performed, the processing unevenness is small and there is no image defect over a long period of time. It was found that stable treatment was possible.

That is, the above object of the present invention is achieved by the following configuration.
(1) A processing method of a lithographic printing plate in which a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer on a support is subjected to laser exposure, and then the photosensitive lithographic printing plate is developed, and the exposed photosensitive plate When the photopolymerizable photosensitive layer in the unexposed area is rubbed and removed by rotating the exposed surface of the photosensitive lithographic printing plate against the rubbing member, the development processing of the photosensitive lithographic printing plate is terminated. And a reverse rotation process in which the rubbing member is rotated in a direction opposite to the direction in which the rubbing member rotates during the development process period, within a development pause period from the start of development of the next photosensitive lithographic printing plate to the start of development. Processing method for printing plates.
(2) The lithographic plate according to claim 1, wherein a high-definition screen corresponding to a size of 250 lines or more as an AM screen and a minimum pixel size constituting a halftone dot of 50 μm or less is used as an FM screen for the exposure. Processing method for printing plates.
(3) The lithographic printing plate processing method according to claim 1 or 2, wherein the reverse rotation process is continuously performed continuously during a development suspension period of the photosensitive lithographic printing plate.
(4) The reverse rotation process is performed during the development pause period of the photosensitive lithographic printing plate for substantially the same period as the development process period of the photosensitive lithographic printing plate developed immediately before. Item 3. A lithographic printing plate processing method according to Item 2.
(5) The lithographic printing plate processing method according to claim 1 or 2, wherein the reverse rotation process is performed every predetermined period.
(6) A lithographic printing plate automatic developing apparatus for developing a photosensitive lithographic printing plate after laser exposure of a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer on a support,
A rubbing member that rotates while being pressed against the plate surface of the photosensitive lithographic printing plate after exposure to rub off the photopolymerizable photosensitive layer of the unexposed portion of the plate surface, and the rubbing member, the rubbing member of the photosensitive lithographic printing plate A rotation direction during the development processing period, and a rotation direction during the development processing period within a development pause period from the end of the development processing of the photosensitive lithographic printing plate to the start of development of the next photosensitive lithographic printing plate; A lithographic printing plate automatic developing device comprising: a rubbing member rotation control means for rotating in a reverse direction.
(7) The lithographic printing plate automatic developing device according to (6), wherein the rubbing member is a brush material.
(8) The lithographic printing plate automatic developing device according to claim 6 or 7, wherein a plurality of rubbing members are arranged side by side and at least one of them is reversed.

  The high-definition screen includes an AM high-definition screen and an FM screen. The AM high-definition screen corresponds to 250 lines or more, and a Co-Re screen manufactured by Fuji Photo Film Co., Ltd. can be suitably used. .

FM screens include Fuji Photo Film's FM screen TAFFETA (20), CREO's Staccato (10, 20, 25, 35, 36), Dainippon Screen's Randot, RandotX (10, 15, 20) Stain Screening manufactured by Heidelbelg and Cristal Raster manufactured by Agfa can be used.
As hybrid screens, Dainippon Screen's Fairdot and Agfa's Sublima are known.

  In the above AM screen having 250 lines or more, the above-described FM screen, and hybrid screen, when the size of the minimum pixel constituting the halftone dot is 50 μm or less, image unevenness easily occurs, and the present invention is effective.

The present invention is a processing method and a processing apparatus for a lithographic printing plate in which a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer on a support is scanned and exposed by a laser and then transported to a development processing section for development. While the photosensitive lithographic printing plate is not developed, partial processing unevenness can be prevented by rotating the rubbing member in a direction opposite to the developing direction. Uneven processing is a brush that is rubbed with the edge of a plate with a small processing plate size when a large lithographic printing plate is processed after developing a large number of small lithographic printing plates. This is caused by streaks (so-called after small plate) when a plate with a larger part is processed, and the portion corresponding to the portion processed with a small lithographic printing plate has a halftone dot around it. The concentration is high. The occurrence of such processing unevenness can be prevented, the brush bed is eliminated, and the service life is extended, so that stable processing without image defects can be performed over a long period of time.
In particular, as a photosensitive lithographic printing plate, a remarkable effect is exhibited when using a high-definition screen corresponding to a size of 250 lines or more as an AM screen and a minimum pixel size of 50 μm or less as an FM screen. The

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As the automatic developing apparatus used in the present invention, any apparatus can be used as long as it includes heating, pre-water washing, development, water washing and finishing steps. A planographic printing plate processing method and an automatic developing apparatus according to the present invention will be described below with reference to the drawings.

  1 and 2 show a basic configuration of an automatic developing apparatus according to this embodiment. The automatic developing apparatus 1 includes a preprocessing unit 200 shown in FIG. 1 and a development processing unit 10 shown in FIG.

The preprocessing unit 200 will be described.
In the pretreatment unit 200, a pre-heating treatment and a pre-water washing treatment are performed on the planographic printing plate (hereinafter also referred to as a printing plate) 12 prior to the development treatment. The printing plate 12 pre-processed by the pre-processing apparatus 200 is developed by the development processing unit 10, and the development processing unit 10 uses an arbitrary configuration capable of developing the printing plate 12. it can. Further, the pre-processing unit 200 applied to the present embodiment may be used separately from the development processing unit 10 or may be used by being connected to the development processing unit 10.
Alternatively, the preprocessing unit may be eliminated and the processing may be performed only by the developing unit.

  In the pretreatment apparatus 200, a preheating unit 204 is provided in the machine frame 202 on the upstream side in the conveying direction of the printing plate 12, and a prewater washing unit 206 as a prewater washing step is provided on the downstream side.

  In the pre-heating unit 204, a plurality of (three in FIG. 1) skewer rollers 210 are arranged in the heating chamber 208. In the heating chamber 208, a heater 214 is provided on the inlet 212 side, and a circulation fan 216 is provided on the upstream side of the heater 214.

  In the preheating unit 204, when the printing plate 12 passes through the heating chamber 208, the photopolymerizable photosensitive layer of the printing plate 12 is accurately cured so as to have a predetermined temperature and a predetermined heating time, The printing power of the printing plate 12 is increased.

  On the other hand, the printing plate 12 that has passed through the heating chamber 208 is sent from the outlet 218 to the pre-water washing section 206.

  The pre-rinsing section 206 is provided with a water washing tank 220, and a washing tank 222 for storing washing water is formed in the water washing tank 220.

  In the pre-water washing unit 206, the conveyance rollers 224, 226, and 228 are arranged in a staggered manner along the conveyance direction of the printing plate 12 on the pre-heating unit 204 side. The conveyance rollers 224 and 228 are provided so as to face the upper surface of the printing plate 12, and the conveyance roller 226 is disposed between the conveyance rollers 224 and 228 so as to face the lower surface of the printing plate 12.

  As a result, the printing plate 12 sent to the pre-water washing unit 206 is transported between the transport rollers 224 and 228 and the transport roller 226.

  In the pre-water washing section 206, a brush roller 230 and a backup roller 232 are provided in pairs in the vertical direction on the downstream side of the conveying roller 228. The contact position between the brush roller 230 and the backup roller 232 is lower than the lower end of the transport roller 228. As a result, the printing plate 12 is inclined from between the conveying rollers 226 and 228 and fed between the brush roller 230 and the backup roller 232.

  Further, the pre-water washing unit 206 is provided with a spray pipe 234 between the conveying roller 228 and the brush roller 230, and a spray pipe 236 is provided above the brush roller 230.

  The cleaning water ejected from the spray pipe 236 is supplied to the entire area along the axial direction of the brush roller 230, and the cleaning water is supplied to the brush material substantially uniformly. Then, the printing plate 12 is brushed by the brush roller 230 to which cleaning water is supplied.

  As a result, the printing plate 12 is fed between the brush roller 230 and the backup roller 232 in a state where the cleaning water is supplied to the surface and the cleaning water is accumulated.

  The protective layer provided on the printing plate 12 is easily swollen by washing water and easily peeled off. Accordingly, the printing plate 12 is brushed by the brush roller 230 in a state where cleaning water is accumulated on the surface, the protective layer is surely removed, and the protective layer remains partially. There will be no unevenness.

  The brush roller 230 is configured to obtain a predetermined brush pressure when the printing plate 12 is sandwiched between the backup roller 232 and the printing roller 12. As a result, when the printing plate 12 passes between the brush roller 230 and the backup roller 232 while rotating in a predetermined direction, the surface of the printing plate 12 is brushed by the brush roller 230.

  On the other hand, a skewer roller 238 is provided in the pre-wash unit 206 on the downstream side of the brush roller 230. The skewer roller 238 is arranged on the upper side of the conveying path of the printing plate 12, and the printing plate 12 that has passed between the brush roller 230 and the backup roller 232 is lifted by being brushed by the brush roller 230. , To prevent the transfer path from coming off.

  Further, when the preprocessing unit 200 is connected to the development processing unit 10, the transport roller pair 42 of the development processing unit 10 is in a state in which the planographic printing plate 12 can be transported to the most downstream side of the pre-water washing unit 206. Is provided.

Next, the development processing unit 10 of the automatic developing apparatus 1 will be described.
As shown in FIG. 2, the development processing unit 10 of the automatic developing device 1 supplies a developing unit 14 for processing the printing plate 12 with a developing solution and water for washing the printing plate 12 processed with the developing solution. A washing section 16 for washing with water, a finishing treatment section 18 for applying a gum solution for protecting the printing surface to the printing plate 12 after washing with water, desensitizing treatment and brushing the printing plate, and a drying section 20 for drying the printing plate 12. Are disposed. That is, in the automatic developing device 1, a developing process, a washing process, a finishing process, and a drying process are sequentially arranged along the direction of conveyance of the printing plate 12 (arrow A in FIG. 2).

  A processing tank 22 is provided in the development processing unit 10. In the processing tank 22, a developing tank 24 is formed at a position serving as the developing section 14 as a processing tank, and a washing tank 26 and a finishing tank 28 are formed at positions serving as the washing section 16 and the finishing processing section 18. Further, the processing tank 22 is provided with a space for the insertion section 34 on the upstream side of the developing tank 24 (upstream in the transport direction of the printing plate 12), and a space for the drying section 20 is formed on the downstream side of the finishing processing tank 28. Has been.

  In the outer panel 30 covering the periphery of the processing tank 22, a slit-like insertion port 32 is formed on the insertion side of the printing plate 12 into the development processing unit 10 (left side in FIG. 1). An insertion portion 34 is formed on the insertion port 32 side of the developing portion 14.

  The development processing unit 10 is provided with covers 36 and 38 that cover the upper part of the processing tank 22 and the upper part of the drying unit 20. The cover 36 on the insertion port 32 side covers the upper part of the washing unit 16 from the insertion part 34 of the processing tank 22, and the cover 38 is disposed so as to cover between the upper part of the washing unit 16 and the upper part of the drying unit 20.

  The cover 36 is provided with an entry insertion port (sub-insertion port) 40 for inserting the printing plate 12 between the developing unit 14 and the water washing unit 16. The sub insertion port 40 is used for inserting the printing plate 12 for processing by the PS plate processor excluding the processing in the developing unit 14.

  A rubber conveyance roller 42 is disposed in the insertion portion 34 adjacent to the insertion port 40. The printing plate 12 on which the image is printed is inserted between the conveying roller pair 42 by being inserted along the direction of arrow A from the insertion port 32.

The transport roller 42 is driven to rotate and feeds the printing plate 12 from the insertion port 32 to the developing unit 14 at an angle in the range of about 15 ° to 31 ° with respect to the horizontal direction. At this time, the front end side of the printing plate 12 in the transport direction is inclined by a predetermined angle with respect to the direction orthogonal to the transport direction. That is, the angle formed by the sub-scanning direction during scanning exposure of the printing plate 12 and the conveyance direction of the printing plate 12 is inclined within a range of 30 degrees to 60 degrees.
Note that, in the development processing unit 10 used for processing the printing plate 12, the development processing unit 10 performs processing with the photosensitive layer (photosensitive surface) facing upward.

  The developing tank 24 formed in the processing tank 22 has a substantially mountain shape with the center of the bottom portion protruding downward, and stores a developing solution for performing the developing process of the printing plate 12. The immersion time is 2 to 60 seconds, preferably 5 to 30 seconds. The immersion temperature is preferably 15 to 50 ° C, more preferably 15 to 50 ° C, and further preferably 20 ° C to 45 ° C.

  In the developing tank 24, a transport roller 48 is disposed on the insertion portion 34 side that is the upstream portion of the transport path of the printing plate 12. In the developing tank 24, a conveyance roller pair 50 is arranged at the center of the conveyance path of the printing plate, and a conveyance roller pair 52 is arranged on the washing unit 16 side which is a downstream part.

  A guide 116 is provided between the transport roller 48 and the transport roller pair 50 in the developing tank 24 of the development processing unit 10. One end of the guide 116 faces the conveyance roller 48, and the other end is directed between the conveyance roller pair 50.

  The printing plate 12 drawn into the development processing unit 10 by the conveying roller pair 42 is sent between the conveying roller 48 and the guide 116 and guided and conveyed on the guide 116 to the conveying roller pair 50.

  In the developing tank 24, a brush roller 141 is disposed in the vicinity of the conveyance roller pair 50 so as to face the guide 116. The brush roller 141 is a long cylindrical member that is driven to rotate about a rotation axis at a predetermined rotation direction and a predetermined rotation speed, and is placed on the surface of the exposure surface of the printing plate 12 conveyed on the guide 116. The contact is brushed by rubbing the upper surface of the printing plate 12. The guide 116 is disposed so that the brush roller 141 contacts the upper surface of the printing plate 12 with a predetermined brush pressure.

  Further, the brush roller 141 protrudes from the liquid surface of the developing solution, and the upper portion protruding from the liquid surface of the brush roller 141 enters the concave portion 100B of the shielding lid 100 together with the conveying roller pair 50. It has become.

  In the developing tank 24, a brush roller 142 is disposed between the conveyance roller pair 50 and 52. The brush roller 142 can have the same configuration as the brush roller 141, and is attached so as to face the upper surface side of the printing plate 12 conveyed between the conveyance roller pair 50, 52. The brush roller 142 is brushed by rubbing the photosensitive layer on the upper surface side of the printing plate 12 by contacting the upper surface of the printing plate 12 while rotating in a predetermined direction and a predetermined rotation direction, and unnecessary photosensitivity by the developer. It is intended to facilitate the removal of the layer. A transport roller 60 is disposed in the vicinity of the brush roller 142 in the downstream side in the transport direction of the printing plate 12. The conveyance roller 60 is attached so as to face the upper surface side of the printing plate 12 conveyed between the conveyance rollers 50 and 52.

  The printing plate 12 drawn from the insertion port 32 by the transport roller 42 passes under the transport roller 48 and is rubbed and brushed by the brush roller 141 before being fed between the transport roller pair 50. Then, the printing plate 12 is guided obliquely upward toward the conveyance roller pair 52 along the bottom surface of the developing tank 24 by the conveyance roller 50. At this time, the upper surface side of the printing plate 12 is rubbed and brushed by the brush roller 142.

In the present embodiment, the brush roller 141 and the brush roller 142 have a shape as shown in the perspective view of FIG. 3 and a brush b such as hair on the surface, and the surface of the exposed surface of the planographic printing plate 12 after exposure. By rubbing, it functions as a rubbing member for removing the photopolymerizable photosensitive layer in the unexposed area.
A back-up roller 45 is provided on the opposite side of the brush roller 141 across the printing plate 12, and a backup plate 46 is disposed on the opposite side of the brush roller 142 across the printing plate 12. In addition, although both the backup roller 45 and the backup plate 46 are provided in this embodiment, the structure provided only corresponding to each brush roller 141,142 may be sufficient as either one. That is, it may be an aspect with or without a backup roller.

  The rubbing member used in the present invention may be any member as long as it can rub the image recording surface of the lithographic printing plate precursor, but it can rub the photopolymerizable photosensitive layer by rotating around the rotation axis. It is particularly preferable to use such a member (for example, a known channel brush, twisting brush, implantation brush, carpet brush, and Morton roller).

  As the channel brush, long so-called channel brushes as disclosed in Japanese Utility Model Laid-Open Nos. 62-167253, 4-63447, 4-64128, and Japanese Patent Laid-Open No. 6-186751 are disclosed. A (band-like brush) wound around the roller body surface in a spiral shape is used.

  As the torsion brush, a torsion brush inserted into a spiral groove provided on the shaft as disclosed in JP-A-3-87832 and spirally wound around the shaft is used. Yes.

  As an implantation brush, what is created by the method of making a small hole in a shaft roller and implanting a brush material is used.

  As a carpet brush, an elongated belt in which a hair material is woven into a woven fabric is wound around the shaft roller as disclosed in JP 2001-5193 A and JP 2001-66788 A. Is used.

  As the Molton roller, a roller part as disclosed in Japanese Patent Laid-Open No. 10-198044 is covered with a cylindrical sliding contact material made of a knitted fabric made of fibers, and the end on the mounting side is tightened. it can.

  When a rotating member is used as the rubbing member, the number of revolutions of the rubbing member is preferably as fast as possible in order to improve the removability of the photopolymerizable photosensitive layer, but the durability of the automatic processor, the manufacturing cost, From the viewpoint of scattering of the developing solution and damage of the exposed portion of the lithographic printing plate precursor, it is preferably 30 to 500 rpm, more preferably 50 to 300 rpm.

  When using a brush as a rubbing member, the number of the brush should just be one or more, and there may be two or more.

  As a brush material used for the rubbing member, natural fibers such as horse hair and pig hair, artificial fibers, metal fibers, and the like are known. However, artificial fibers are preferable in terms of chemical resistance. Man-made fibers include polyamides such as nylon 6, nylon 6,6, nylon 6,10, nylon 6,12 and nylon 12, polyesters such as polyethylene terephthalate and polybutylene terephthalate (PBT), polyacrylonitrile, poly (meta ) Polyacrylics such as alkyl acrylate, Polyethylene, Polypropylene, Polystyrene, Polyvinyl chloride, Polyolefins such as poly (vinylidene chloride), Celluloses such as acetylcellulose, Polyurethanes such as polyurethane, Polyphenylene sulfite, Ethylene tetrafluoride Fluorine resins such as ethylene copolymers and polyvinylidene fluoride are used, but considering elasticity, rigidity, wear resistance, heat resistance, chemical resistance, water supply, moisture absorption, etc., nylon 6, nylon 6, 6, Nylon 6 · 10, Nai 6/12, nylon 12, polypropylene, polybutylene terephthalate, and polyethylene terephthalate are preferable. Nylon 6.6, nylon 6.10, 6.12, nylon 12, polybutylene terephthalate (PBT), and polypropylene are preferably used. . Of the polyesters, polybutylene terephthalate (PBT) is particularly preferable. Of the polyolefins, polypropylene is particularly preferred.

The thickness of the brush is not particularly limited, but is preferably 0.01 mm to 1.0 mm, and more preferably 0.2 mm to 0.5 mm. This is because if the thickness of the brush is thinner than 0.01 mm, the rubbing property is inferior, and if it is thicker than 1.0 mm, the plate surface is easily scratched.
Further, the length of the bristles of the brush is not particularly limited, but is usually in the range of 3 mm to 50 mm. This is because if the length is shorter than 3 mm, the contact with the planographic printing plate precursor becomes non-uniform and the plate surface is easily scratched. On the other hand, when the length is longer than 50 mm, the advantage in development processing due to the increase in length is not found, which is disadvantageous economically. In the case of a Molton roller, since the cylindrical sliding contact material which consists of a knitted material is covered, the regulation of the thickness length of a bristle material is unnecessary.

  In the automatic developing apparatus 1 of the present embodiment, the brush rollers 141 and 142 as rubbing members are used when brushing the printing plate 12 as shown in FIG. 6 (backup roller type) and FIG. 7 (backup plate type). The rotation direction can be switched between normal rotation and reverse rotation about the rotation axis. When one brush roller is normal rotation, the other brush roller can be reversed. Further, when three or more brush rollers are applied as the rubbing member, at least one of the brush rollers is reversed.

  These brush rollers are driven and controlled by a system conceptually shown in FIG. 8, which is a rubbing member rotation control means. In FIG. 8, a case is considered in which the brush rollers 141 and 142 are driven to rotate by, for example, normal rotation operation and reverse rotation operation. In this case, the timing generator 33 generates a timing signal for reversing the motor drive in accordance with the processing contents in the development processing unit or information such as the elapsed time of the development processing from the timer 31. The control unit 35 receives this timing signal, generates a drive signal for the motor M based on a command from the CPU in the control unit 35, and outputs the drive signal to the motor driver 37. As a result, the motor M is rotationally driven, and control is performed so that the brush roller shaft R has a desired rotational direction and rotational speed.

  When the transport position of the printing plate 12 is detected by an optical position sensor or the like and the printing plate 12 is not directly under the brush rollers 141 and 142, the brush rollers 141 and 142 are appropriately moved as shown in FIGS. By controlling the vertical movement by a simple driving means, it is possible to adjust the brush pressure during reverse rotation driving. In FIG. 6, the brush roller 141 is reversely driven while being in contact with the backup roller 45, and in FIG. 7, the brush roller 142 is reversely driven while being in contact with the backup plate 46. By adjusting the brush pressure, the litter at the tip of the brush is reliably returned.

  Returning to FIG. 2 again, the conveying roller pair 52 provided on the downstream side in the conveying direction in the developing unit 24 has, for example, an outer peripheral portion formed of a rubber roller.

  In the developing tank 24, a spray pipe 56 is provided in the vicinity of the bottom surface between the conveyance roller pair 50 and the conveyance roller pair 52. The developer is ejected from the spray pipe 56. Thereby, the developing solution in the developing tank 24 is agitated, and the printing plate 12 can be uniformly processed.

  After the photopolymerizable photosensitive layer is removed by the brush rollers 141 and 142, the printing plate 12 is pulled out from the developing tank 24 while being sandwiched by the transport roller pair 52. The printing plate 12 drawn out from the developing tank 24 by the conveying roller pair 52 is sent to the washing unit 16 while the developer attached to the surface is squeezed out by the conveying roller pair 52.

  In the water washing section 16, a conveyance path for conveying the printing plate 12 in a substantially horizontal state is formed by a pair of conveyance rollers 62 and 64 disposed above the washing tank 26. The printing plate 12 includes conveyance rollers 62, 64 is horizontally transported above the washing tank 26.

  In the water washing section 16, spray pipes 66 and 68 are provided between a pair of conveyance rollers 62 and 64, with the conveyance path of the printing plate 12 being sandwiched up and down. The spray pipes 66 and 68 have an axial direction arranged along the width direction of the printing plate 12 (a direction orthogonal to the conveying direction), and a plurality of discharge holes (not shown) facing the conveying path of the printing plate 12 in the axial direction. Are formed along.

  In the washing tank 26, for example, water (hereinafter referred to as "washing water") is stored as a cleaning agent. In the automatic developing device 10, a water supply pump (not shown) synchronizes with the conveyance of the printing plate 12, The washing water in the washing tank 26 is supplied to the spray pipes 66 and 68. As a result, washing water is ejected from the spray pipes 66 and 68 toward the printing plate 12 to wash away the developer adhering to the surface of the printing plate 12.

  The washing water supplied to the printing plate 12 is squeezed from the front and back surfaces of the printing plate 12 together with the developer and the like adhering to the front and back surfaces of the printing plate 12 when the printing plate 12 is held between the conveying roller pair 64 and sent out. It is dropped and collected in the washing tank 26. The spraying direction of the washing water from the spray pipes 66 and 68 is such that the spray pipe 66 is on the upstream side in the conveyance direction of the printing plate 12 and the spray pipe 68 is on the downstream side in the conveyance direction of the printing plate 12. It may be in another direction. Further, a new washing water solution is supplied to the washing tank 26 by means (not shown) according to the processing amount of the printing plate 12.

  In the water washing section 16, a brush for brushing the plate surface of the printing plate 12 may be disposed between the conveying roller pairs 62 and 64.

  The finishing processing unit 18 is provided with a transport roller pair 70 above the finishing processing tank 28, and the printing plate 12 is transported toward the transport roller pair 70 by the transport roller pair 64, thereby passing through the interior of the finishing processing unit 18. After being conveyed, the sheet is nipped by the conveying roller pair 70 and sent toward the drying unit 20.

  The finishing processing unit 18 is provided with a spray pipe 72 above the transport path of the printing plate 12 and a spray pipe 74 below the transport path. The spray pipes 72 and 74 have a longitudinal direction (axial direction) along the width direction of the printing plate 12, and are arranged above and below the conveyance path of the printing plate 12. A plurality of discharge holes are formed in the spray pipes 72 and 74 along the width direction of the printing plate 12.

  In the finishing tank 28, a gum solution used for protecting the printing plate 12 is stored, and the gum solution is supplied to the spray pipes 72 and 74 in synchronization with the conveyance of the printing plate 12. The spray pipe 72 drops the gum solution onto the printing plate 12 and spreads it on the surface of the printing plate 12 and applies it. The spray pipe 74 discharges the gum solution from the discharge hole toward the back surface of the printing plate 12 and applies the gum solution to the back surface of the printing plate 12.

  The printing plate 12 has a protective film formed by a gum solution applied to the front and back surfaces. In addition, the discharge direction of the gum solution from the spray pipe 72 is not limited to the downstream side in the transport direction of the printing plate 12, and may be other directions, and a rectifying plate is provided and ejected toward the rectifying plate. The gum solution may be applied to the surface of the printing plate 12 while being uniformly diffused along the width direction of the printing plate 12 with a current plate. Further, instead of the spray pipe 74, a discharge unit for applying the gum solution to the back surface of the printing plate 12 by moving the printing plate 12 in contact with the discharged gum solution may be used.

  The finishing processing unit 18 is provided with a cleaning spray 76 above the conveying roller pair 70 and a cleaning roller 78 that rotates while contacting the roller above the conveying roller pair 70, and is set in advance. At a predetermined timing, the cleaning water is dropped from the cleaning spray 76 to the contact position between the cleaning roller 78 and the roller above the conveying roller pair 70 via the rectifying plate 80, thereby supplying the cleaning water to the conveying roller pair. 70 is uniformly diffused on the peripheral surface of the roller above 70, and the gum solution is washed away from the peripheral surfaces of the upper and lower rollers of the conveying roller pair 70, and the gum solution adheres to the peripheral surfaces of the rollers and damages the photopolymer plate 12. To prevent it.

  The gum solution is applied by the finishing processing unit 18, and the printing plate 12 is sandwiched between the conveying roller pair 70, and is sent to the drying unit 20 with the gum solution remaining slightly on the front and back surfaces (the gum solution remains as a thin film). It is done.

  In the development processing unit 10, a partition plate 82 is provided between the finishing processing unit 18 and the drying unit 20. The partition plate 82 is disposed above the conveyance path of the printing plate 12 so as to face the upper end of the processing tank 22, and thereby, a slit-shaped insertion port is provided between the finishing processing unit 18 and the drying unit 20. 84 is formed. In addition, the partition plate 82 has a double structure, whereby a groove-like air passage is formed on the drying unit 20 side of the insertion port 84, and the air in the drying unit 20 enters the passage. Air in the drying unit 20 is prevented from entering the finishing processing unit 18 from the insertion port 84.

  In the drying unit 20, a support roller 86 that supports the printing plate 12 is disposed in the vicinity of the insertion port 84, and in the vicinity of the central portion in the conveyance direction of the printing plate 12 and the discharge port 88. A roller pair 90 and a conveying roller pair 92 are disposed. The printing plate 12 is transported in the drying unit 20 by a support roller 86 and transport roller pairs 90 and 92.

  Ducts 94 and 96 are disposed between the support roller 86 and the transport roller 90 and between the transport roller pair 90 and the transport roller pair 92 in pairs with the transport path of the printing plate 12 interposed therebetween. The ducts 94 and 96 are disposed such that the longitudinal direction thereof is along the width direction of the printing plate 12, and a slit hole 98 is provided on a surface facing the conveyance path of the printing plate 12.

  The ducts 94 and 96 discharge the dry air from the slit hole 98 toward the conveying path of the printing plate 12 when the dry air generated by the dry air generating means (not shown) is supplied from one end side in the longitudinal direction. And sprayed onto the printing plate 12. Thereby, as for the printing plate 12, the gum liquid currently apply | coated to the front and back is dried, and a protective film is formed.

  The printing plate 12 on which the protective film is formed is nipped by the conveying roller pair 92 and is carried out of the development processing unit 10.

  Here, the development processing unit 10 described above will be further described. In the development processing unit 10, the liquid level lid 100 is disposed in the development tank 24 so that the developer in the development tank 24 comes into contact with carbon dioxide gas in the air. This prevents the deterioration and moisture evaporation caused by this. A blade-shaped shielding member (not shown) formed of silicon rubber or the like is provided between the shielding lid 100 and the processing tank 22 and the conveying roller 48 and the conveying roller 52, so that the developer in the developing tank 24 is fresh. It is more preferable to prevent contact with the outside air or evaporation of moisture in the developer.

  Furthermore, a preservative may be automatically added to the pre-wash water and the wash water in order to suppress the growth of scale, mold, etc. As a scale inhibitor, BK-3 manufactured by Fuji Photo Film Co., Ltd. is suitable. Used for. As addition amount, it is 50-5000 ppm, Preferably it is 100-3000 ppm.

  The AM high-definition screen corresponds to 250 lines or more, but a Co-Re screen manufactured by Fuji Photo Film Co., Ltd. can be suitably used.

  Examples of FM screens include Fuji Photo Film FM screen TAFFETA (20), CREO Staccato (10, 20, 25, 35, 36), Dainippon Screen Randot, Randot X (10, 15). 20), Stain Screening manufactured by Heidelbelg and Cristal Raster manufactured by Agfa can be used.

  As hybrid screens, Dainippon Screen's Fairdot and Agfa's Sublima are known. Specifically, there are AM screens of 250 lines or more, more preferably 300 lines or more, FM screens, and hybrid screens described above. In the FM screen and the hybrid screen, when the size of the minimum pixel constituting the halftone dot is 50 μm or less, image unevenness is likely to occur. Particularly, when the size is 30 μm or less, image unevenness is likely to occur, and the present invention is effective.

  Here, the size of the minimum pixel represents the length of one side of the minimum pixel constituting the image. FIG. 4 shows a highlight portion of the FM screen. FIG. 5 shows the halftone of the FM screen. As shown in FIGS. 4 and 5, the minimum pixel can be seen on the highlight side, and a part of the minimum pixel can be seen on the halftone and shadow sides.

  Thus, the lithographic printing plate processing method and automatic developing apparatus according to the present invention scan and expose a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer on a support with a laser, and then convey it to the development processing unit 10. When developing, the printing plate 12 is a high-definition screen corresponding to an AM screen of 250 lines or more and an FM screen corresponding to a size of the minimum pixel constituting a halftone dot of 50 μm or less. While the photosensitive lithographic printing plate is not developed, the rubbing member is rotated in a direction opposite to the developing direction. As a result, as shown in FIG. 14, when a large lithographic printing plate is processed after a large number of lithographic printing plates are developed, a place corresponding to the portion where the small lithographic printing plate is processed. However, there is no processing irregularity in which the halftone dot density is higher than the surrounding area, and stable processing without image defects can be performed over a long period of time.

  That is, when the printing rubbing member 12 is not yet processed, if the developing rubbing member is rotated in the direction opposite to the developing processing direction, the sleeping of the developing brush as shown in FIG. 15 is eliminated, so that there is no image defect. Stable processing is possible. Moreover, the effect which extends the lifetime of the bristle material of a brush is also acquired.

Here, examples of the reverse rotation driving method include the following timings (1) to (5). Control of these timings is based on the rubbing member rotation control means shown in FIG.
(1) Reverse rotation processing is always performed during non-processing As shown in the time chart of FIG. 9, the rotation directions of the two brushes A (brush 141) and brush B (flash 142) are normal, and the brush A is normal during the development processing. In the case of rolling, the brush B is rotated in the reverse direction, and during non-development processing, the brush B is always continuously rotated in the opposite direction. That is, the reverse rotation process is always continuously performed during the development suspension period of the photosensitive lithographic printing plate. In this case, the reverse rotation process is always performed during the development pause time, thereby facilitating control and reliably returning the brush tip to the bed.

(2) Reverse rotation processing is performed for the same time as the processing time. As shown in the time chart of FIG. 10, assuming that the development processing time is t1, t3, and the non-development processing time is t2, t4, t1 = t2, t3 = t4. It is what. That is, the reverse rotation process is performed during the development pause period of the photosensitive lithographic printing plate for substantially the same period as the development process period of the photosensitive lithographic printing plate developed immediately before. In this case, since the brush tip is reversely rotated for the same time as the developing process, the original state can be reliably restored without waste.

(3) Reverse rotation processing at the end of development processing and automatic termination As shown in the time chart of FIG. 11, the reverse rotation processing is reverse rotation at the end of development processing, for example, in synchronization with pressing of a stop switch when the apparatus is stopped. Perform the process. In this case, the brush tip remains in the original state until the next device startup, and the life of the brush can be extended.

(4) Reverse rotation processing is performed when the automatic developing apparatus is started up As shown in the time chart of FIG. 12, reverse rotation processing is executed during warm-up when the apparatus is started up. In this case, since the reverse rotation process can be performed within the waiting time for warming up, the development process can be efficiently performed without wasting time.

(5) Reverse rotation is performed periodically. As shown in the time chart of FIG. By performing the reverse rotation process every predetermined fixed period, the control becomes simple, and by selecting the time corresponding to the contents of the development process, it is possible to perform the optimal brush laying down.

Next, the plate making of the photosensitive lithographic printing plate used in the present invention will be supplemented below.
The photosensitive lithographic printing plate used in the present invention has a photopolymerizable photosensitive layer on a support. In addition, an undercoat layer may be provided between the support and the photopolymerizable photosensitive layer as necessary, and a protective layer (oxygen blocking layer) may be provided on the photopolymerizable photosensitive layer. Examples of the photosensitive lithographic printing plate include photosensitive lithographic printing plates having a photopolymerized photosensitive layer as described in JP-A Nos. 2004-4145 and 2005-84303.

  The photosensitive lithographic printing plate of the present invention is usually subjected to image exposure, and then an unexposed portion of the photosensitive layer is removed with a developer to obtain an image.

  In addition, as the plate making process of the photosensitive lithographic printing plate of the present invention, the entire surface may be heated before exposure, during exposure, and between exposure and development, if necessary. By such heating, the image forming reaction in the photosensitive layer is promoted, and advantages such as improvement in sensitivity and printing durability and stabilization of sensitivity may occur. Furthermore, for the purpose of improving the image strength and printing durability, it is also effective to subject the developed image to full post heating or full exposure. Usually, heating before development is preferably performed under mild conditions of 150 ° C. or less. If the temperature is too high, problems such as covering up to the non-image area occur. Very strong conditions are used for heating after development. Usually, it is in the range of 200 to 500 ° C. If the temperature is low, sufficient image strengthening action cannot be obtained. If the temperature is too high, problems such as deterioration of the support and thermal decomposition of the image area occur.

  As a method for exposing a scanning exposure lithographic printing plate according to the present invention, a known method can be used without limitation. A desirable wavelength of the light source is 350 nm to 450 nm, and specifically, an InGaN semiconductor laser is suitable. The exposure mechanism may be any of an internal drum system, an external drum system, a flat bed system, and the like. Among these exposure mechanisms, the internal drum system is particularly effective.

As a laser, an Ar ion laser (364 nm, 351 nm, 10 mW to 1 W), a Kr ion laser (356 nm, 351 nm, 10 mW to 1 W), a He-Cd laser (441 nm, 325 nm, 1 mW to 100 mW), and a solid laser, Nd: YAG Combination of (YVO ₄ ) and SHG crystal × 2 times (355 nm, 5 mW to 1 W), combination of Cr; LiSAF and SHG crystal (430 nm, 10 mW), KNbO ₃ ring resonator (430 nm, 30 mW) as a semiconductor laser system , A combination of waveguide type wavelength conversion element and AIGaAs, InGaAs semiconductor (380 nm to 450 nm, 5 mW to 100 mW), a combination of waveguide type wavelength conversion element and AIGaInP, AIGaAs semiconductor (300 nm to 350 nm, 5 mw to 100 w), AIGaInN ( 50nm~450nm, 5mW~30mW) As other pulsed laser, _{N 2} laser (337 nm, pulse: 0.1 to 10), XeF (351 nm, pulse 10 to 250 mJ) are exemplified. In particular, AIGaInN semiconductor lasers (commercially available InGaN-based semiconductor lasers 400 to 410 nm, 5 to 30 mw) are suitable in terms of wavelength characteristics and cost.

  In addition, a heating process for 1 second to 5 minutes at a temperature of 50 ° C. to 150 ° C. for the purpose of increasing the curing rate of the photopolymerization type photosensitive layer after image exposure with conventionally known actinic light and development. By providing, it is possible to increase the curability of the non-image area and further improve the printing durability, which is more preferable.

  The above-mentioned photosensitive lithographic printing plate can be developed using a conventionally known developer to form an image. These conventionally known developers are described in JP-B-57-7427. Such a developing solution is mentioned.

  Further, the developed photosensitive lithographic printing plate can be washed with water or a surfactant as described in JP-A Nos. 54-8002, 55-1115045 and 59-58431. And a desensitizing solution containing gum arabic, starch derivatives and the like. In the post-treatment of the photosensitive lithographic printing plate of the present invention, these treatments can be used in various combinations. The lithographic printing plate obtained by such processing is applied to an offset printing machine and used for printing a large number of sheets.

[Example 1]
Hereinafter, although the remarkable effect of the present invention is explained based on an example, the range of the present invention is not limited to these examples.

  (Examples 1 to 3 and Comparative Example 1)

(Evaluation of image unevenness on FM screen)
A high-sensitivity photosensitive lithographic printing plate PN-V for violet laser manufactured by Fuji Photo Film Co., Ltd. was prepared by the following method, and image unevenness on an FM screen was evaluated. Mounted on a Violet semiconductor laser setter Vx9600 (InGaN semiconductor laser 405 nm ± 10 nm emission / output 30 mw) manufactured by FujiFILM Electronic Imaging LTD, with an exposure amount of 90 μJ / cm ² and resolution of 2438 dpi, with Fuji Photo Film FM screen, TAFFETA20 A 50% flat mesh was drawn.

As a printing plate size to be processed, a lithographic printing plate having a width direction of 650 mm and a longitudinal direction of 550 mm was used as a small size. As the large size, a lithographic printing plate having a width direction of 1030 mm and a longitudinal direction of 800 mm was used. Table 1 shows the processing method and the timing for rotating the developing brush in the direction opposite to the processing direction. This timing corresponds to the above-described reverse rotation methods (1) to (4).
The exposed printing plate was sent to an automatic developing device, heated at 100 ° C. for 10 seconds, the PVA protective layer was washed away with water, and subsequently the developing temperature was 28 ° C. and the developing time was 20 seconds. The developing brush roller b (141, 142) shown in FIG. 3 is also equipped with two channel brushes having an outer diameter of 4.8 mm. Nylon 610 was used as the hair material, the hair material diameter was 0.07 mm, and the hair material length was 16 mm. The front brush roller had a rotational speed of 110 rpm in the same rotational direction as the conveying direction. The rear brush roller was rotated at a rotation speed of 110 rpm in the rotation direction opposite to the conveying direction.
The developer was prepared by diluting a developer DV-2 manufactured by Fuji Photo Film Co., Ltd. five times with water. The developed plate was washed with a rinse bath and then sent to the finishing processing section, and a Fuji Photo Film Co., Ltd. gum solution FP-2W diluted twice with water was used. The finished plate was discharged after hot air drying to obtain a lithographic printing plate on which a 50% flat screen of an FM screen was drawn. The flat net unevenness of the obtained lithographic printing plate was evaluated. The results are shown in Table 1.

  As shown in Table 1, all of Examples 1 to 4 corresponding to the timing examples (1) to (4) of the above-described reversal processing could be processed stably without unevenness of the flat mesh on the plate. On the other hand, in Comparative Example 1 in which the reverse rotation process was not performed, the flat net unevenness on the plate was severely generated.

It is a figure which shows the structure of the pre-processing part of the automatic development apparatus of the planographic printing plate which concerns on this invention. It is a figure which shows the structure of the image development processing part of the automatic developing apparatus shown in FIG. FIG. 3 is a perspective view of a developing brush roller of the developing processing unit shown in FIG. 2. It is a figure which shows the highlight part of FM screen. It is a figure which shows the halftone of FM screen. FIG. 3 is an explanatory diagram of a rotation direction of the developing brush roller shown in FIG. 2. FIG. 3 is an explanatory diagram of a rotation direction of a backup plate type developing brush roller shown in FIG. 2. It is a figure which shows the rotation control system of the brush roller shown in FIG. FIG. 3 is a time chart when the developing brush roller shown in FIG. 3 is a time chart when the developing brush roller shown in FIG. 2 is reversely rotated for the same time as the processing time. 3 is a time chart when the developing brush roller shown in FIG. 2 is reversely rotated at the end of processing. 3 is a time chart when the developing brush roller shown in FIG. 2 is reversely rotated when it is started up in the morning. 3 is a time chart when the developing brush roller shown in FIG. 2 is periodically reversely rotated. It is explanatory drawing of the process nonuniformity of the conventional automatic image development apparatus. It is explanatory drawing of the litter of the brush bristle material of the conventional automatic developing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Automatic developing device 10 Development processing part 12 Printing plate 14 Developing part 16 Water washing part 18 Finishing processing part 20 Drying part 24 Developing tank 141, 142 Developing brush roller 200 Pre-processing part

Claims (8)

A method for processing a lithographic printing plate comprising developing a photosensitive lithographic printing plate after laser exposure of a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer on a support,
The exposed surface of the photosensitive lithographic printing plate after exposure is rotated by pressing a rubbing member to remove the photopolymerizable photosensitive layer in the unexposed area by rubbing and developing the photosensitive lithographic printing plate. A reverse rotation process is performed in which the rubbing member is rotated in a direction opposite to the direction in which the rubbing member rotates during the development processing period within a development pause period from the end of the processing to the start of development of the next photosensitive lithographic printing plate. A processing method of a lithographic printing plate characterized by the above.   2. The lithographic printing plate according to claim 1, wherein a high-definition screen corresponding to a minimum screen size of 50 [mu] m or less is used as an AM screen and an FM screen with a minimum pixel size of 50 [mu] m or less. Processing method.   The lithographic printing plate processing method according to claim 1 or 2, wherein the reverse rotation process is continuously performed continuously during a development suspension period of the photosensitive lithographic printing plate.   3. The reverse rotation process is performed during the development suspension period of the photosensitive lithographic printing plate for substantially the same period as the development process period of the photosensitive lithographic printing plate developed immediately before the photosensitive lithographic printing plate. Lithographic printing plate processing method. The lithographic printing plate processing method according to claim 1, wherein the reverse rotation process is performed every predetermined period. A lithographic printing plate automatic developing apparatus for developing a photosensitive lithographic printing plate after laser exposure of a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer on a support,
A rubbing member that rotates while pressing against the plate surface of the photosensitive lithographic printing plate after exposure to rub off the photopolymerizable photosensitive layer of the unexposed portion of the plate surface;
The rubbing member is rotated during the development processing period of the photosensitive lithographic printing plate, and within the development suspension period from the end of the development processing of the photosensitive lithographic printing plate to the start of development of the next photosensitive lithographic printing plate And a rubbing member rotation control means for rotating in a direction opposite to the direction of rotation during the development processing period;
An automatic developing device for a lithographic printing plate, comprising:   7. The lithographic printing plate automatic developing device according to claim 6, wherein the rubbing member is a brush material.   The lithographic printing plate automatic developing device according to claim 6 or 7, wherein a plurality of rubbing members are arranged side by side and at least one of them is reversed.

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