JP2007132997A - Processing apparatus for planographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a processing apparatus for a planographic printing plate, which will give not adverse influence on an automatic platemaking machine, caused by elution failures in the end-face portion of a photosensitive material due to pressure fog upon development, even in a planographic printing plate which requires a chamfering process, and can carry out stable development processing over a long time, without the adherence of dirt on the surface of a conveying roll. <P>SOLUTION: The processing apparatus is constituted so that a planographic printing plate, subjected to chamfering on its end face, is immersed in at least a developing liquid, while conveying the plate held between rolls to dissolve and remove a non-image part; and then the plate is subjected to rinse water treatment, wherein among the conveying rolls in the rinse water processing section, the surface of the roll at least in the upper side at the entrance has water-repellence and oil-repellence properties. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a processing device for a lithographic printing plate, particularly a lithographic printing plate in which a photosensitive layer is photopolymerizable.

  In recent years, direct plate-making systems using various lasers such as ultraviolet, visible, and infrared (computer-to-plate, acronyms are also called CTP systems for directly making computer-generated image information) are available. It has been put into practical use and is widely used in the field of general commercial printing. This direct plate making system is advantageous in comparison with conventional plate making systems using film in terms of speed, cost, stability, etc. by digitizing the system, and is becoming mainstream in today's general commercial printing market.

  Due to these advantages, the direct plate making system is spreading not only in the general commercial printing market but also in the newspaper printing market. In newspaper printing, printing conditions are severer than general commercial printing because of its large number of copies and high printing speed, and high printing durability is required for printing plates. For this reason, negative type photopolymerizable photosensitive materials capable of forming an image with higher strength by a crosslinking reaction than positive type photosensitive materials have been used in conventional film plate making systems. For this reason, a lithographic printing plate having high image strength was indispensable for introducing a direct plate-making system into the newspaper printing market.

  Conventional film-making systems using negative photosensitive materials cause a cross-linking reaction of the photosensitive layer by prolonged contact exposure with a very high energy light source such as a mercury lamp. The image obtained was very strong. In the direct plate making system, since exposure processing is performed with lower exposure energy than these light sources, it was initially difficult to form an image with the same intensity, but in recent years, various photosensitivities have been developed to improve the image intensity. Materials have been developed. In particular, high-power semiconductor lasers that emit light in the infrared region of 750 nm or more are becoming more compact and higher-powered and are very useful as exposure light sources for direct plate-making systems. In the plate making system, the development of photosensitive materials has made remarkable progress, and various proposals have been made.

  For example, the photosensitive material described in JP-A-7-20629 is characterized in that it contains a resole resin, a novolak resin, a latent Bronsted acid, and an infrared absorber, and can be used for both positive and negative plates. The version is described. JP-A-2000-089452 discloses a cross-linkable compound having a unique structure, and a binder is a polymer having an aromatic hydrocarbon ring directly bonded to a hydroxy group or an alkoxy group in a side chain or main chain, In addition, a negative image recording material containing a compound that generates an acid by heat and an infrared absorber is described. JP-A-2001-272778 discloses a photosensitive material comprising a borate complex salt, a trihaloalkyl-substituted compound, and a sensitizing dye having absorption in a wavelength range from near infrared light to infrared light. Are listed.

  However, in the lithographic printing plate (hereinafter referred to as CTP printing plate) corresponding to these direct plate making, there has been a problem that has not been seen in the general commercial printing field in the newspaper printing field. It is pressure fogging by chamfering of the end face.

  Unlike general commercial printing, newspaper printing often requires frequent replacement of printing plates. Therefore, it is common to place multiple printing plates on a single plate cylinder and perform printing while replacing printing plates as necessary. . However, when a plurality of printing plates are printed side by side on a single plate cylinder, the border between adjacent printing plates appears linearly on the printed paper surface due to ink on the cut surface of the printing plate, so-called frame contamination. It becomes a printing failure called. In order to prevent this printing failure, the lithographic printing plate used for newspaper printing is generally chamfered in the lithographic printing plate in the manufacturing process.

  The chamfering process referred to in the present invention is a process of chamfering the end face of a lithographic printing plate. When cutting a lithographic printing plate to a required size by a cutting finishing machine such as a flying shear, rotary shear, or guillotine, the clearance of the blade This means that the edge of the surface on which the photosensitive layer is applied is scraped off while having an oblique linear shape or a curvature. FIG. 2 shows a schematic cross-sectional view of a lithographic printing plate that has been chamfered. In FIG. 2, b represents a lithographic printing plate support, and a represents a photosensitive layer. Moreover, c shows the side part formed by the chamfering process. Further, A represents the horizontal length from the end face of the support removed by the chamfering process, and B represents the vertical length from the photosensitive layer surface of the part removed by the chamfering process. The values of A and B are not particularly limited, but are generally 50 μm to 200 μm.

  When this chamfering process is performed, the photosensitive layer is locally subjected to a large pressure by the blade of the cutting and finishing machine, and the photosensitive layer is strongly pressed against the support. The pressed photosensitive layer may be embedded in the support, or the components in the photosensitive layer may be altered by pressure, resulting in a change in dissolution during development. This is particularly noticeable in the case of a printing plate for direct plate making using a laser that has higher sensitivity than the PS plate. As a result, an elution defect portion is formed on the end face of the photosensitive material, and a phenomenon called pressure fogging sometimes occurs. In addition, the photosensitive layer may wrap around the side surface of the support during the chamfering process, and elution of the wrapped photosensitive layer will be delayed during the development process, and it will not peel off from the side surface of the support and will remain on the plate as a poorly eluted portion. There were cases where it remained. These poorly eluted portions appeared as residual films in various forms such as needles, thin layers, and grains on the end face of the lithographic printing plate after development, causing a plate making failure.

  Further, since the elution by the developing solution is weaker than that at the rear end at the top of the processing, the occurrence is remarkable. The reason why the elution property of the head part becomes weak is that, in the method of immersing in the developer, it is not horizontally transported but is transported in a curved shape to the developer reservoir, so that it is separated from the developer reservoir upward. This is because the liquid breakage is improved and the development is completed earlier than the rear end. On the contrary, the rear end portion will be supplied more abundantly after being drawn into the air from the developer storage portion by the excess liquid from the squeeze roll, so that a difference occurs.

  If this poorly eluted portion cannot be completely removed by the developing unit of the plate-making processing device, it is sandwiched by the transport roll of the water washing unit in the next process, but in the case of a developer immersion type, it is detached from the solution and transported. When the printing plate is directed upward, it first hits the upper roll and then nips, so if there is an elution failure part at the processing head part of the printing plate, the elution failure part strongly against the part where the printing plate head contacts Sometimes peeled off by impact and transferred. In this case, the ink is accumulated on the roll as the number of plate-making plates increases, and gradually retransfers to the surface of the printing plate to be processed thereafter. In some cases, the printing plate quality is deteriorated due to printing stains, and the maintainability of the water-washing section conveyance roll is lowered.

Many immersion development type processing apparatuses have been proposed so far (for example, the processing apparatuses described in Patent Documents 1 and 2), both of which are caused by transfer dirt due to the residual film on the end face and dirt on the washing unit transport roll. No corresponding one has been proposed.
Japanese Patent Laid-Open No. 8-248642 JP 2000-298357 A

  Therefore, the problem of the present invention is that even in a lithographic printing plate that requires chamfering processing, there is no adverse effect on the automatic plate making machine due to the elution failure portion of the photosensitive material end surface due to pressure fog during development, and the surface of the transport roll is soiled. An object of the present invention is to provide a lithographic printing plate processing apparatus capable of performing a stable development process for a long period of time without sticking.

It has been found that the above object of the present invention can be achieved by the processing apparatus for a lithographic printing plate described below.
1. In the processing apparatus for rinsing the lithographic printing plate whose end face has been chamfered by being nipped in at least a developing solution while being conveyed by nipping the roll, and at least one of the conveyance rolls of the rinsing treatment unit, An apparatus for processing a lithographic printing plate in which the roll surface above the entrance has water and oil repellency.
2. 2. The processing apparatus for a lithographic printing plate as described in 1 above, wherein the washing roll above the entrance has a scraping member.
3. 3. The processing apparatus for a lithographic printing plate according to 1 or 2, wherein the lithographic printing plate is a CTP printing plate that is directly exposed using a laser beam as a light source.

  According to the present invention, even if the chamfering process applied to newspaper printing is performed, there is no elution failure of the end face portion of the photosensitive layer due to pressure fog or the like, and an excellent effect can be obtained that can obtain a printing plate in which no frame smear occurs even in printing. can get.

  As a result of intensive studies by the inventor, it has been clarified that a plate making apparatus in which at least the roll surface on the upper side of the entrance has water and oil repellency is extremely useful for the above problems.

  The development processing apparatus according to the present invention will be described below with reference to FIG. FIG. 1 is a sectional view of an automatic processor showing an example of the present invention. The lithographic printing plate 100 subjected to exposure processing in FIG. 1 is inserted into an automatic developing machine with the photosensitive layer surface facing upward, and is transported into the development processing section by transport rolls 1 and 2, and at a constant temperature via transport auxiliary rolls 3 and 4. And dipped in a temperature-controlled developer.

  While the photosensitive layer of the lithographic printing plate immersed in the developer is in a state in which the unexposed portion, which is a non-image portion, is swollen by the developer and is easily eluted, the submerged transport rollers 3 and 4 and the transport auxiliary roll 5, 6 to the scraping section. Elution is promoted by rubbing the swollen non-image area by the scraping roll 7. On the other hand, the image area where the crosslinking reaction has occurred by exposure hardly swells in the developer and remains as an image.

  Next, the lithographic printing plate on which an image is formed by elution of the non-image portion is squeezed with a developer squeezing roll 9, 10 to squeeze the excess developer on the plate surface, and is conveyed to the water washing processing unit which is the next step. In the washing unit, the surface of the planographic printing plate 100 is washed with washing water discharged from the washing shower pipes 14 and 15 while being conveyed by the washing conveyance rolls 11 and 12. The surface of the washing transport roll 11 is coated with a Teflon (R) resin that is water and oil repellent, and even if a part of the photosensitive layer that has been completely dissolved and removed by the transport of the planographic printing plate 100 is adhered. Easily detached by washing water. Further, a resin blade 30 is installed as a scraping member on the washing / conveying roll 11, and further detachment is promoted to clean the entire washing / conveying roll 11 in the width direction.

  Thereafter, the water washing liquid is squeezed by the water washing conveyance rolls 16 and 17 and conveyed to a gum processing unit (not shown). In the gum processing section, a gum solution is applied to form a protective film on the surface of the planographic printing plate, and finally, drying is performed in the drying processing section.

  The structure of the washing roll that is a feature of the present invention will be described in more detail. The surface of the water-washing roll may be water- and oil-repellent as long as it is prepared by wrapping a metal roll center axis with a water- and oil-repellent fluororubber or fluororesin elastic body, or a general-purpose rubber roll. A water- and oil-repellent fluororesin can be coated or a water- and oil-repellent heat-shrinkable tube can be attached. The water / oil repellency in the present invention refers to the property that the surface is difficult to wet with water and oil, and here it is defined by the contact angle with water and oil. The contact angle is obtained by using the material to be measured as a test piece and displaying the angle between the plane of the test piece formed when a water or oil drop is dropped and the water or oil drop as a scale. Generally, it can be easily measured using a commercially available contact angle meter. Water drops may be 60 degrees or more when pure water is used, and 60 degrees or more when linseed oil is added as oil drops. More preferably, when a water drop or an oil drop is dropped, any contact angle is 60 degrees or more, and any one contact angle is 90 degrees or more. More preferably, any one is 120 degrees or more. Such a high contact angle indicates that it is difficult to get wet with water or oil, and therefore it can be easily removed even if it adheres to the roll surface. As a material exhibiting such water / oil repellency, fluororesin or fluororubber can be preferably used. Examples of the fluororesin include polytetrafluoroethylene resin, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin, tetrafluoroethylene / hexafluoropropylene copolymer resin, and the like. As the water- and oil-repellent heat-shrinkable tube, a Gunze RC heat-shrinkable tube, a Nitto Denko Nitoflon heat-shrinkable tube, or the like can be used.

  Next, the scraping member of the present invention will be described. The surface is urged against a water-washing roll having water and oil repellency, and promotes the detachment of the photosensitive layer and other dirt components attached to the surface, which cannot be completely dissolved and removed, from the water-washing roll. As long as it is in contact with the washing roll at any position on the circumference, a position of 45 degrees to 90 degrees with respect to the nip position is preferable. As the material of the scraping member, metal, rubber or resin can be used, but at least the contact portion is preferably an elastic body in consideration of long-term stability due to damage to the surface of the washing roll.

  Next, the operation mechanism of the present invention will be described. In the case where the washing transport roll 11 in FIG. 1 is not water- and oil-repellent, when the poorly eluted portion of the photosensitive layer from the planographic printing plate in which pressure fogging has occurred due to the chamfering treatment contacts the washing transport roll, the photosensitive layer Is inherently hydrophobic and is attracted to a roll with a low contact angle of water and oil, making it easy to transfer. In addition, since the poorly eluted portion of the photosensitive layer transferred onto the water-conveying roll is not easily detached because the roll surface is easily wetted, the accumulated dirt starts to be transferred from the roll to the printing plate. On the other hand, when the water-washing transport roll 11 has water and oil repellency, the surface of the roll is not affected even when the elution failure portion of the photosensitive layer from the planographic printing plate in which pressure fogging has occurred due to the chamfering treatment is brought into contact with the water-washing transport roll. Since it is water and oil repellent, it is difficult to attract and repels, so transfer to the washing and transporting roll is difficult to occur, and even if it is transferred, it is difficult to get wet, so that it does not remain as dirt. Therefore, subsequent transfer of dirt to the printing plate does not occur, and as a result, contamination of the processing liquid after the washing liquid and the development processing apparatus itself can be prevented. In addition, it is possible to obtain a good printed matter free from stains in printing.

  Next, the planographic printing plate used in the present invention will be described. As the lithographic printing plate used in the present invention, a conventionally known lithographic printing plate can be used. In particular, a chamfering treatment used for newspaper printing is sufficiently effective. In addition, the CTP plate used for newspaper printing is more sensitive than the PS plate, and the occurrence of pressure fog due to the chamfering process becomes more prominent, so that it can be used more effectively. Examples of these printing plates include lithographic printing plates characterized by containing a resole resin, a novolak resin, a latent Bronsted acid and an infrared absorber described in JP-A-7-20629, and JP-A 2000-2000. The compound having crosslinkability described in Japanese Patent No. 089452 has a unique structure, and the binder is a polymer having an aromatic hydrocarbon ring directly bonded to a hydroxy group or an alkoxy group in a side chain or main chain, and an acid is generated by heat. A lithographic printing plate containing a generated compound and an infrared absorber, a borate complex salt described in JP-A-2001-272778, a trihaloalkyl-substituted compound, and an increase having absorption in a wavelength range from near infrared light to infrared light region. Examples thereof include a lithographic printing plate characterized by containing a dye-sensitive dye. In particular, the photosensitive layer of a lithographic printing plate has a copolymer of a monomer having a polymerizable double bond in the side chain and a carboxyl group-containing monomer as a polymerizable polymer, and lithographic printing having an organic boron salt as a photopolymerization initiator The plate can be applied effectively because it is more sensitive.

  The developer used in the present invention will be described. Any alkaline aqueous solution can be used as long as it is an alkaline liquid having a pH of 8 or more and can be dissolved in the lithographic printing plate to be used in a predetermined time. Examples of the alkali agent include inorganic alkalis such as sodium hydroxide and potassium hydroxide, organic alkali agents such as monomethylamine, dimethylamine and trimethylamine, and alkali metal silica such as sodium silicate, potassium silicate and lithium silicate. Examples thereof include acid salts and ammonium silicate. These can be used alone or in combination of two or more. Further, anionic, cationic, nonionic and amphoteric surfactants can be added singly or in combination in consideration of elution adjustment and detergency after dissolution.

  A printing plate developed with a developer having such a composition is then post-treated with a washing water, a rinse solution containing a surfactant, a finisher mainly composed of gum arabic or starch derivatives, or a protective gum solution. Applied. In the post-treatment of the printing plate of the present invention, these treatments can be used in various combinations. For example, development → water washing → rinsing liquid treatment containing surfactant or development → water washing → finisher liquid treatment is a rinse liquid or finisher. Less liquid fatigue is preferable. Furthermore, a countercurrent multistage process using a rinse liquid or a finisher liquid is also a preferred embodiment. These post-processing are generally performed using an automatic developing machine including a developing unit and a post-processing unit. As the post-treatment liquid, a method of spraying from a spray nozzle or a method of conveying through a treatment tank filled with the treatment liquid is used. A method is also known in which a fixed amount of a small amount of washing water is supplied to the plate surface after development, and the waste liquid is reused as dilution water for the developer stock solution. In such automatic processing, each processing solution can be processed while being replenished with the respective replenishing solution according to the processing amount and operating time. In addition, a so-called disposable processing method in which treatment is performed with a substantially unused post-treatment liquid can also be applied.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples as well as the effects.

  The automatic plate making machine in the present embodiment will be described below with reference to FIG. FIG. 1 is a schematic sectional view of a developing portion of an automatic plate making machine showing an example of the present invention. The lithographic printing plate 100 subjected to exposure processing in FIG. 1 is inserted into an automatic developing machine with the photosensitive layer surface facing upward, and is transported into the development processing section by transport rolls 1 and 2, and at a constant temperature via transport auxiliary rolls 3 and 4. And dipped in a temperature-controlled developer.

  The photosensitive layer of the lithographic printing plate immersed in the developer is transported to the scraping part by the submerged transport rolls 5 and 6 while the unexposed part, which is a non-image part, is swollen by the developer and is easily eluted. Is done. Elution is promoted by rubbing the swollen non-image area by the scraping roll 7. On the other hand, the image area where the crosslinking reaction has occurred by exposure hardly swells in the developer and remains as an image.

  Next, the lithographic printing plate on which an image is formed by elution of the non-image portion is squeezed with a developer squeezing roll 9, 10 to squeeze the excess developer on the plate surface, and is conveyed to the water washing processing unit which is the next step. In the washing unit, the surface of the planographic printing plate 100 is washed with washing water discharged from the washing shower pipes 14 and 15 while being conveyed by the washing conveyance rolls 11 and 12. The surface of the washing transport roll 11 is coated with a Teflon (R) resin that is water and oil repellent, and even if a part of the photosensitive layer that has been completely dissolved and removed by the transport of the planographic printing plate 100 is adhered. Easily detached by washing water. Furthermore, a resin blade 30 is installed as a scraping member on the washing / conveying roll 11 so as to promote further detachment and to be cleaned over the entire width direction of the washing / conveying roll 11.

  Thereafter, the water washing liquid is squeezed by the water washing conveyance rolls 16 and 17 and conveyed to a gum processing unit (not shown). In the gum processing section, a gum solution is applied to form a protective film on the surface of the planographic printing plate, and finally, drying is performed in the drying processing section.

  A commercially available CTP printing plate for newspaper printing (PD-News 300 manufactured by Mitsubishi Paper Industries, 1100 mm × 398 mm) was chamfered using a commercially available shearing machine (M-1245 manufactured by Amada). At this time, by adjusting the clearance of the blade edge, a planographic printing plate of the following chamfered processed product 1 and a non-chamfered processed product 2 substantially not formed with a chamfered processing part was prepared. The end face shape of the chamfered product 1 was 50 μm in the horizontal direction from the end face of the support, which is A in FIG. 2, and 50 μm in the vertical direction from the surface of the photosensitive layer, which was B in FIG. .

For the lithographic printing plates 1 and 2 produced as described above, laser irradiation was performed at a drum rotation speed of 1000 rpm using an external drum type plate setter (Dainippon Screen Manufacturing Co., Ltd. PT-R4000) equipped with an 830 nm semiconductor laser. The exposure process was carried out with the energy fixed at 50 mJ / cm ² , and then the development process was carried out with the automatic plate making machine.

  With the above-mentioned automatic plate making machine, each of the chamfered processed product 1 and the chamfered processed product 2 was processed continuously for 500 plates, and the plate surface was observed from the first plate-making product to the 500th plate-making product. There was no abnormality, and good printed matter was obtained even after printing. In addition, the washing transport roll 11 after completion of the plate making showed no particular adhesion of dirt. Next, a continuous plate-making process was carried out in the same manner as described above only by replacing the washing transport roll 11 of the washing section with a roll formed of nitrile butadiene rubber having a hydrophobic surface (lipophilic). Although not reflected on the printed matter, it was confirmed that the portion of the printing plate where the processing head portion gradually contacted from the 300th plate was transferred. On the other hand, in the chamfered processed product 2, the plate surface was good up to the 500th plate. Further, when the resin blade 30 in the washing section was removed and the same processing was performed, in the chamfered processed product 1, the transfer of the portion where the processing head portion gradually contacted the plate surface from the 100th plate was confirmed, and in the 500th plate The result was reflected as a stain on the print. On the other hand, the chamfered processed product 2 was not reflected in printing up to the 500th plate, but the transfer of partial stains was confirmed on the plate surface, and the stains on the water washing transport roll were severe, and it took time to clean.

  As an application example of the present invention, it can be used as an automatic developing device for a CTP printing plate for the newspaper printing field.

It is a cross-sectional schematic diagram of a processor showing an example of the present invention. 1 is a schematic cross-sectional view of a lithographic printing plate that has been chamfered according to the present invention.

Explanation of symbols

a Photosensitive layer of planographic printing plate b Support of planographic printing plate c Side surface formed by chamfering process A Horizontal length from the end surface of the support removed by chamfering process B Part of the part deleted by chamfering process Length in the vertical direction from the surface of the photosensitive layer 100 Planographic printing plate 101 Lead portion of the lithographic printing plate 1, 2, transport roll 3, 4, transport auxiliary roll 5, 6, submerged transport roll 7 scraping roll 8 guide plate 9, 10 development aperture Rolls 11, 12 Flushing rolls 14, 15 Flushing shower pipes 16, 17 Flushing rolls 30 Resin blades

Claims (3)

  In the processing apparatus for rinsing the lithographic printing plate whose end face has been chamfered by squeezing the roll while immersing it in at least the developer by leaching and removing the non-image part, at least of the transport rolls of the rinsing unit An apparatus for processing a lithographic printing plate, wherein the roll surface on the upper side of the entrance has water and oil repellency.   2. The processing apparatus for a lithographic printing plate according to claim 1, further comprising a scraping member in the washing roll on the upper side of the entrance.   3. The processing apparatus for a lithographic printing plate according to claim 1, wherein the lithographic printing plate is a CTP printing plate that is directly exposed using a laser beam as a light source.

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