JP2005144692A - Plate-making method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a printing plate having a printing part showing excellent strength, resolution and oil sensitivity using an inkjet type plate-making method. <P>SOLUTION: The plate-making method comprises steps of; an imaging liquid resin containing a plurality of monomers or oligomers being a photo-polymerizable component and a solvent being a non-photo-polymerizable component is adhered to a print original plate provided with a water absorbing and water resistant porous layer to form a desired image pattern; at least a part of a solvent is released from the image creating resin by infiltrating the solvent in the porous layer; and the image creating resin is cured by the photopolymerization. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for making a lithographic printing plate by an ink jet method, which can directly produce a lithographic printing plate from digital information without going through a film having a negative or positive image.

  Due to recent advances in computer technology, the digitization of information in the printing field has rapidly progressed, and a plate making method capable of producing a lithographic printing plate from digital information output from a computer or the like without using a plate making film has attracted attention. Yes. As such a plate-making method, a method of directly forming a printing ink-receptive image line portion by an ink jet method has been proposed. The ink jet method does not require a complicated optical system, so that the apparatus can be simplified, less maintenance is required, and the plate-making cost can be expected to be greatly reduced.

  Examples of the plate making method for directly forming a printing ink-receptive imaged area or non-imaged area by an inkjet method include, for example, a printing ink repellent material such as curable silicone on the surface of a printing original plate (support). There is known a method for producing a printing plate by adhering a film by an inkjet method (for example, see Patent Document 1 and Patent Document 2).

  Also known is a method of forming an oleophilic (grease-sensitive) image line portion by attaching a water-based ink or oil-based ink containing a oil-sensitive component to a printing original plate by an inkjet method (for example, Patent Documents). 3, see Patent Document 4 and Patent Document 5.)

Furthermore, 5-40% by weight of a curable component selected from polyester acrylate, polyether acrylate, epoxy acrylate, alkyd acrylate, and urethane acrylate, and 10-60% by weight of a reactive diluent depending on an electrical signal corresponding to an image signal. A photosensitive ink prepared to have a composition in which the photopolymerization initiator is 0.1 to 10% by weight, the solvent (solvent) is 10 to 80% by weight, and the dye is 30% by weight or less is applied onto the printing plate material by an inkjet method. A method is known in which an image portion is formed by adhesion, and the image portion is cured by light irradiation (see, for example, Patent Document 6). This plate making method basically includes the following three steps: (1) a step of converting a document image to be made into data into an electrical signal, and (2) operating an ink jet head in accordance with the electrical signal obtained in (1). And a process of forming a photosensitive ink image on the printing plate material, and (3) a process of exposing the printing plate material having the photosensitive ink image to cure the photosensitive ink image.
JP 51-84303 A JP-A-56-113456 JP-A-7-304278 JP-A-8-324145 Japanese Patent Laid-Open No. 9-24599 Japanese Patent No. 2542500

  However, in the techniques described in Patent Document 1 and Patent Document 2, a printing plate obtained as a result of plate making is a planographic printing method in which an ink repellent material for printing formed on the surface of a printing original plate is used as a non-image portion. It is a version. Accordingly, the printed image is inferior in the resolution of the shadow part or the reverse part. In this method, a printing ink repellent material needs to be adhered to the entire non-image area that occupies most of the printing plate surface, so that a large amount of image forming ink is required.

  Further, in the techniques described in Patent Document 3, Patent Document 4 and Patent Document 5, a printing original plate used for a conventional lithographic printing plate is commonly used, and the surface of the printing original plate has hydrophilicity and water retention. Various treatments such as graining, anodizing, and hydrophilization are performed to improve the quality. Therefore, the spread of the image forming ink attached to the surface of the printing original plate cannot be sufficiently suppressed, and a problem is a decrease in resolution due to bleeding of the image forming ink. An ink composition having a very high surface tension is used as the image forming ink in order to form the image area directly on the surface of the hydrophilic printing original plate by the ink jet method while suppressing such bleeding of the image forming ink. However, it is conceivable that the printing ink does not sufficiently deposit on the image area formed by such an ink composition, and as a result, a good printed matter cannot be obtained.

  In the technique described in Patent Document 6, a solvent is added for the purpose of adjusting the viscosity of the photosensitive ink. Therefore, under conditions where non-hardening components such as solvents are present in a mixture, the photopolymerizable material is unavoidable of a decrease in photopolymerization efficiency, and has an effect of improving the fixability to a recording medium such as paper. However, the effect of exhibiting durability as a printing plate cannot be obtained. In this conventional technique, a conventionally known offset master plate coated with zinc oxide, a waterless lithographic plate coated with a silicone compound, a grained aluminum plate, etc. are used as a printing plate (printing plate). ing. Therefore, for example, in a grained aluminum plate, various treatments such as graining, anodizing, and hydrophilization are performed to improve surface hydrophilicity and water retention, and large and small irregularities are formed. Since the size is sufficiently larger than the molecular size of the photosensitive ink, the photosensitive ink adhering to the surface of the printing original plate enters the unevenness as it is, and the photosensitive ink that does not enter spreads along the surface, causing blurring and resolution. Decreases.

  The present invention has been made on the basis of such knowledge, and in plate making of a printing plate by an ink jet method, a plate making method capable of providing a printing plate having an image line portion excellent in strength, resolution and oil sensitivity. The purpose is to provide.

  In order to achieve the above object, the plate making method according to the present invention comprises a plurality of monomers or oligomers that are photopolymerizable components and a solvent that is a non-photopolymerizable component, as shown in claim 1 of the claims. A process of forming a desired image pattern by adhering the liquid image-forming resin contained on a printing original plate provided with a water-absorbing and water-resistant porous layer, and by allowing the solvent to permeate the porous layer The process has a process of separating at least a part of the solvent from the image forming resin and a process of curing the image forming resin by photopolymerization.

  According to this, in the process of forming an image pattern, the viscosity of the image-forming resin can be adjusted to be relatively low by a solvent, so that a large ejection force is required when performing image formation using an inkjet recording head or the like. In addition, the image forming resin can be easily discharged from the recording head (nozzle), and the image forming resin can be attached to the printing original plate as fine droplets. Furthermore, before the process of curing the image forming resin attached to the printing original plate, the solvent, which is a non-photopolymerizable component that inhibits the curing, is separated, so that the polymerization efficiency of the photopolymerizable component of the image forming resin is increased. The image pattern can be improved to form a robust image pattern, and the image forming resin can be prevented from bleeding and a high-resolution image pattern can be formed.

  In the plate making method, as shown in claim 2, the image-forming resin can contain 3 to 50% by weight of a solvent that is a non-photopolymerizable component. Thus, in the process of forming an image pattern, the viscosity of the image forming resin can be adjusted to be relatively low by the solvent, while in the process of separating the solvent, the solvent is quickly separated from the image forming resin. Can do.

  In the plate making method, as shown in claim 3, the printing original plate is formed by applying a base material and inorganic material particles having a plurality of pores having an average diameter of 30 to 500 mm on the base material together with a water-resistant binder. The water-absorbing and water-resistant porous layer can be used. Thereby, a porous layer having water resistance and water absorption by capillary action can be easily formed on the printing original plate.

  In the plate making method, as shown in claim 4, the inorganic material particles can be composed of alumina or alumina hydrate and porous silica. Thereby, the photopolymerizable component contained in the image forming resin is trapped in the particles of alumina or alumina hydrate or porous silica particles, and the image forming resin is prevented from bleeding and a high-resolution image pattern can be formed.

  In the plate making method, as shown in claim 5, the alumina or the alumina hydrate can be formed by gelation of alumina sol. Thereby, as a material for forming the porous layer, it is possible to easily obtain alumina or alumina hydrate having a particle size and pores that are relatively controlled at a lower temperature using a sol-gel method.

  In the plate making method, as shown in claim 6, the alumina or alumina hydrate can be pseudoboehmite. Thereby, as a material for forming the porous layer, it is possible to easily obtain alumina or alumina hydrate having a particle size and pores that are relatively controlled at a lower temperature using a sol-gel method.

  In the plate making method, as shown in claim 7, the base material can be configured to be PET or paper having water-resistant treatment on both sides. Thereby, it is possible to obtain a printing original plate having good workability and low cost by using polyethylene terephthalate (PET) or paper.

  In the plate making method, as shown in claim 8, the base material is mainly an aluminum, and the porous layer is an alumite layer having a thickness of 5 μm to 50 μm provided by anodizing the surface of the base material. There can be a certain configuration. Thereby, the base material and porous layer of a printing original plate can be formed with a single material, and the manufacturing process of the printing original plate can be simplified, and at the same time, peeling of the porous layer can be prevented.

  In the plate making method, as shown in claim 9, the alumite layer can have a large number of pores having a pore diameter of approximately 100 to 500 and substantially perpendicular to the surface thereof.

  As a result, after the image forming resin is attached to the printing original plate, only the solvent can efficiently penetrate into the alumite layer and be separated from the image forming resin. A pattern can be formed. Further, since the solvent, which is a non-photopolymerizable component that inhibits curing, can be efficiently separated, the polymerization efficiency of the photopolymerizable component of the image-forming resin can be improved and a more robust image pattern can be formed. Furthermore, since the hole diameter is smaller than the particles of the printing ink, it is possible to prevent the printing ink from entering the hole and causing printing stains in the printing process.

  In the plate making method, as shown in claim 10, the image-forming resin can be configured such that the surface after curing is oleophilic. As a result, when printing is performed on a rotary press using a printing plate after plate making, oil-based printing ink efficiently adheres to the surface of the cured image-forming resin, thereby enabling high-density printing.

  In the plate making method, as shown in claim 11, the solvent may be amphiphilic. As a result, when printing on a rotary press using a printing plate after plate making, the dampening solution to be attached before applying the printing ink to the printing plate adheres to the solvent in which the image forming resin is blotted. This prevents printing ink from adhering, prevents smudges, and at the same time enables high-resolution printing.

  In the plate making method, as shown in claim 12, the image forming resin may have a viscosity of 4 to 30 centipoise. As a result, it is possible to more easily discharge the image forming resin from the recording head without requiring a large discharge force when performing image formation using an inkjet recording head or the like. Higher resolution image patterns can be formed by adhering to the printing original plate as fine droplets.

  ADVANTAGE OF THE INVENTION According to this invention, the platemaking method which can provide the printing plate provided with the image part which was excellent in intensity | strength, resolution, and oil-sensitivity in platemaking of the printing plate by an inkjet system can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 are diagrams schematically showing a process of forming an image pattern by the plate making method of the present invention. These differ in the configuration of the printing original plate, but the other configurations are generally the same.

  In FIG. 1, a printing original plate 102 includes a base material 103 mainly composed of aluminum and a porous layer 104 provided on the surface of the base material 103. The porous layer 104 is composed of fine particles of inorganic material having fine pores (for example, alumina or a mixture of alumina hydrate and porous silica) and a water-resistant binder.

  Alumina or alumina hydrate is a porous aluminum oxide having a radius of 30 to 100 mm in order to absorb the non-polymerizable solvent 106 in the image pattern forming process and absorb dampening water in the printing process. Or a hydrated product thereof. At this time, the pore size distribution of the dry solid content of alumina or alumina hydrate can be measured using a nitrogen adsorption method (constant flow rate method) as a means for measuring pore properties. Here, the gel-like product obtained by drying the alumina sol is suitable as alumina or alumina hydrate used in the present invention. Among these, coagulated boehmite is optimal as a substance used for the porous layer of the present invention, and pseudoboehmite sol obtained by drying the sol is particularly preferable. Alumina or alumina hydrate may be either crystalline or amorphous, and any suitable form such as amorphous particles or spherical particles can be used.

  As the porous silica particles, in the same manner as the above alumina or alumina hydrate, the non-polymerizable solvent 106 is absorbed in the image pattern forming process and the dampening water is absorbed and retained in the printing process. Those having an average pore diameter of about 2 to 50 μm and an average pore diameter of 80 to 500 mm are preferable.

  As the binder material, polyvinyl alcohol is mainly used, but various other modified polyvinyl alcohols such as cation modified, anion modified and silanol modified, starch derivatives and modified products thereof, cellulose derivatives, styrene-maleic acid copolymers and the like are suitably used alone. Alternatively, they can be mixed and used.

  When manufacturing the printing original plate 102 as described above, it is usual to use a method in which alumina or a mixture of alumina hydrate and porous silica particles is prepared and applied to the substrate 103 together with a binder. As the application means, for example, various methods such as an air knife coater, a blade coater, a bar coater, a rod coater, a roll coater, a gravure coater, and a size press can be used.

  Here, the amount of alumina or alumina hydrate used is suitably about 5 to 50% by weight based on the porous silica particles. When the amount used is less than the lower limit, the object of the present invention cannot be sufficiently achieved. Conversely, when the amount exceeds the upper limit, the absorption rate is undesirably slowed. Also, by making the pore diameter of alumina or alumina hydrate and porous silica particles smaller than the color material of the printing ink, the color material of the printing ink enters the pores in the printing process and causes printing stains. This can be prevented. The porous layer 104 of the printing original plate 102 thus produced has a structure in which a capillary structure composed of fine pores of inorganic material fine particles and fine gaps formed by the inorganic material fine particles and a binder spreads vertically and horizontally.

  Note that the porous layer 104 of the printing original plate 102 shown in FIG. 1 may have a configuration in which only alumina or hydrated alumina having fine pores is applied together with a binder. Further, it goes without saying that a printing original plate can be formed by applying a porous material having water-resistant fine pores having a pore diameter of about 80 to 500 mm on the substrate.

  In FIG. 1, an image-forming resin 101 mainly comprises a plurality of oligomers or monomers that are photopolymerizable components, a polymerization initiator and a reactive agent 105, and a solvent 106 that is a non-photopolymerizable component. . This image-forming resin 101 is a liquid ultraviolet-curing resin that undergoes a photopolymerization reaction upon irradiation with ultraviolet light, and contains 8 wt% of hydrocarbon, alcohol, ketone, ether alcohol, ether, ester, and the like as the solvent 106.

  Here, as an oligomer of the image forming resin 101, polyester acrylate, epoxy acrylate, urethane acrylate, or the like can be used. Since such an oligomer or monomer has a high viscosity, it is difficult to form fine droplets at high speed when it is attached to the printing original plate 102 by an ink jet method. Therefore, the viscosity is adjusted to about 4 to 30 centipoise (cP) with a low-viscosity reactive diluent and solvent. The photopolymerization initiator generates radicals by light energy (ultraviolet rays), which reacts with a reactive group of an oligomer or monomer to initiate polymerization.

  In this embodiment, the viscosity of the image forming resin 101 is adjusted appropriately, and the solvent content is set to 8% by weight so that the solvent 106 can be easily separated from the image forming resin 101 described later. However, the content of the solvent is not limited to this, and the content of the solvent can be selected in the range of 3 to 50% by weight in consideration of the addition amount of the reactive diluent and the optimum viscosity for ejection by the ink jet method. Further, long-term storage stability and stability can be secured by adding various adjusting agents such as a polymerization inhibitor and an antifoaming agent for preventing dark reaction to the image forming resin 101.

  When an image pattern is formed on the printing original plate 102 as described above, as shown in FIG. 1A, an image forming resin 101 is applied to a fine liquid from an ejection means (not shown) such as an ink jet recording head. The droplets are discharged toward the surface of the printing original plate 102. As shown in FIG. 1B, the image forming resin 101 that has reached the surface of the printing original plate 102 adheres to the porous layer 104, and then, in the lateral and depth directions due to the capillary action of the pores of the porous layer 104. To penetrate. At this time, the molecular size of the solvent 106 constituting the image-forming resin 101 is very small compared to the pore diameter of the porous layer 104. Therefore, the interaction with the pore wall is small and vertically and horizontally without being trapped. It penetrates. On the other hand, the molecular size of each material of the photopolymerizable component 105 is larger than the molecular size of the solvent 106, and the interaction with the pore walls (for example, suction force such as van der Waals force and Coulomb force) is larger. Therefore, it is easily trapped in the wall of the pore and hardly penetrates. As a result, the photopolymerizable component 105 and the solvent 106 constituting the image forming resin 101 are separated, and the photopolymerizable component 105 generally stays on the porous layer 104 at the position where the image forming resin 101 is adhered, A solvent 106 exists so as to spread around the periphery.

  After the process of forming the image pattern by adhering the image forming resin 101 to the printing original plate 102 and the process of separating the solvent 106 from the image forming resin 101, the image pattern is further cured by light irradiation. Through the process, the production of the printing plate is completed, and the printing plate is used for printing on a flat printing press (rotary press). In printing, first, dampening water is supplied to a portion of the printing plate where there is no image pattern in order to prevent bleeding of the printing ink. In a conventional printing plate, there are irregularities called large waves and medium waves coated with a hydrophilic material on the surface where there is no image pattern, and these irregularities played a role of retaining water. However, the printing plate produced by the plate-making method of the present invention includes the porous 104 having a water-resistant surface and water retention (water absorption). Exhibits the same performance as the uneven surface. Further, the portion of the image-forming resin 101 where the photopolymerizable component 105 is cured is lipophilic, and therefore repels dampening water. On the other hand, in the portion where the solvent 106 spreads around the portion, the solvent 106 is amphiphilic. So dampening water adheres. As a result, dampening water adheres to areas other than the image area composed of the cured portion of the photopolymerizable component 105.

  Next, printing ink is applied to the printing plate. At this time, since the printing ink is oily, the portion where the fountain solution exists repels the printing ink, and the printing ink is applied only to the oleophilic portion where the photopolymerizable component 105 of the cured image-forming resin 101 exists. Adhere to. Finally, the printing original plate 102 coated with the printing ink is pressed against a rubber blanket to transfer only the printing ink to the blanket, and the printing ink transferred to the blanket is transferred to the paper again to complete the printing. To do.

  On the other hand, in FIG. 2, a printing original plate 107 has a porous layer provided with a large number of fine holes 108 by alumite treatment of the surface of a base material mainly composed of aluminum. The capillary structure of the porous layer is composed of innumerable fine holes 108 extending in the vertical direction (thickness direction of the printing original plate) and fine grooves formed by surface irregularities.

  Here, although the hole diameter and depth of the fine hole 108 can be variously changed depending on the chemical used for anodizing and the treatment time, in this embodiment, the hole diameter is 100 to 500 mm and the depth is 25 to 50 μm. Selected by range. The micropore 108 has a pore diameter as close as possible to the molecular size of the material of the photopolymerizable component 105 so that the interaction with the molecule of the material of the photopolymerizable component 105 is large, and the image forming resin to be attached It is desirable that the depth be such that the solvent 106 contained in the 101 droplets can be reliably absorbed. Therefore, the optimum pore diameter is selected depending on the molecular size of the material of the photopolymerizable component 105 contained in the droplets of the image forming resin 101, and the optimum depth is selected depending on the volume of the droplets.

  As a result, when an image pattern is formed on the printing original plate 107, as shown in FIG. 2B, most of the image forming resin 101 attached to the printing original plate 107 has a depth due to the capillary phenomenon of the fine holes 108. It penetrates in the direction, and the remaining small amount penetrates in the lateral direction by the fine grooves formed by the surface irregularities. For this reason, the image-forming resin 101 separates the photopolymerizable component 105 and the solvent 106 constituting the image-forming resin 101 in the same manner as in FIG. Therefore, the photopolymerizable component 105 is trapped near the surface of the micropore 108, and the solvent 106 exists in the deep portion of the micropore 108. Thus, in the state where the separation of the solvent 106 from the image forming resin 101 is completed, only the photopolymerizable component 105 exists in the vicinity of the surface of the fine hole 108 where the image pattern is formed, and the solvent 106 is excluded. Therefore, the photopolymerizable component 105 can be efficiently polymerized by irradiation with light (ultraviolet rays).

  FIG. 3 is a diagram showing an example of a plate making apparatus used for carrying out the plate making method of the present invention. Here, for the sake of convenience, only the schematic configuration of the printing plate preparation unit of the plate making apparatus is shown. The printing plate preparation unit includes a conveyance mechanism (conveying means) including an insertion roller 202 and a conveyance roller 203 that engage with a non-image area (outside of a recording area) of the printing original plate 201 and convey the printing original plate 201, A linear motor 20 (scanning means) 6 comprising a stator 204 installed so as to cross the printing original plate 201 conveyed by the conveyance mechanism and a slider 205 moving along the stator 204, and mounted on the slider 205, are in the form of droplets. An inkjet recording head 207 (recording means) having a plurality of nozzles for discharging an ultraviolet curable resin and an ultraviolet ray having an irradiation width wider than the width of the printing original plate 201 and curing the ultraviolet curable resin discharged to the printing original plate 201 It is mainly composed of a lamp (curing means) 208.

  As shown in the figure, the linear motor 206 includes a plurality of permanent magnets 209 provided on the stator 204, a linear guide 210 that supports and guides the slider 205, a linear scale 211, and a linear sensor 212 attached to the slider 205. The linear scale 211 is detected at 212, and the detected signal is sent through a cable 213 to a control circuit (not shown). In the control circuit, the speed and position of the slider 205 based on the detection signal of the linear scale 212 and the signal for controlling the discharge of the ultraviolet curable resin from the recording head 207 provided on the slider 205 are synchronized. At the same time, the control circuit controls the operations of the insertion roller 202 and the transport roller 203 in accordance with the operations of the slider 205 and the recording head 207, and joins the image line portions by the ultraviolet curable resin formed in a strip shape on the printing original plate 201. Do exactly.

  In addition, in order to make the connection of the image line portions more accurate, the same control as various controls in a normal inkjet printer is performed as necessary. Further, the linear motor is not limited to the configuration using the permanent magnet shown here, and various types of linear motors can be used. Alternatively, a mechanism that converts a rotary motion using a rotary motor and a belt into a linear motion is also applicable.

  The ultraviolet lamp 208 includes an ultraviolet lamp main body 214 and a reflection cover 215. The reflective cover 215 is for efficiently irradiating the emitted ultraviolet rays toward the printing original plate 201. On the other hand, unnecessary ultraviolet rays reach the recording head 207 and hit the ultraviolet curable resin of the nozzle portion, This prevents the ultraviolet curable resin from being hardened and being unable to discharge. The ultraviolet lamp 208 is controlled according to the movement of the printing original plate 201 by a control circuit similar to the linear motor 206, the recording head 207, the insertion roller 202, and the conveyance roller 203.

  It is also possible to mount a smaller ultraviolet lamp on the slider 205 of the linear motor 206, or ultraviolet rays emitted from an external light source are applied to the slider 205 via a light guide means such as an optical fiber. It is also possible to irradiate from a held predetermined irradiation part (opening part of the light guide means). Accordingly, the ultraviolet curable resin attached to the printing original plate 201 can be cured when the slider 25 is moved. In addition, the printing plate preparation unit does not include a device for applying a gum solution for protecting the printing original plate 201 that has been subjected to plate making, but may include a gum solution application device after the ultraviolet lamp 208 as necessary. Good. Further, similarly to the ultraviolet lamp 28, it is also possible to mount a smaller gum solution application device on the slider 205 and apply the gum solution to the ultraviolet curable resin that has been cured on the printing original plate 201.

  Next, the operation of the printing plate preparation unit configured as described above will be described.

  First, when the printing original plate 201 is sent to the insertion roller 202 of the transport mechanism, the insertion roller 202 does not damage the image area of the printing original plate 201 (region where the UV curable resin adheres) so as not to damage the image. The printing original plate 201 is sent out by rotating so as to sandwich the line portion from above and below. When the leading edge of the printing original plate 201 passes through the insertion roller 202 and reaches the conveyance roller 203, the conveyance mechanism is stopped and the linear motor 206 is operated. Here, the movement of the slider 205 of the linear motor 206 and the discharge of the ultraviolet curable resin by the recording head 207 are controlled to be synchronized so that the image line portion formed by the ultraviolet curable resin formed in units of a plurality of lines is not disturbed. Furthermore, various control methods are used so that the image line portions formed in units of a plurality of lines are accurately joined and the discontinuity of the image line portions is eliminated. Thus, the ultraviolet curable resin is ejected according to the drawing signal rasterized in units of pages to be printed in advance, and the ultraviolet curable resin is adhered to the portion corresponding to the image of the printing plate.

  The ultraviolet curable resin adhering to the printing original plate 201 is absorbed by the pores of the porous layer of the printing original plate 201, the solvent is separated from the ultraviolet curable resin, and only the photopolymerizable component in the ultraviolet curable resin is near the porous surface. Swelled to form a layer of ink for printing. The formation of the walled layer is closely related to the structure of the porous layer and the amount of droplets ejected from the ink jet recording head 207. For example, in the case of an anodized layer formed by anodizing, the density of micropores And depth is important. When the micropore diameter is relatively larger than the molecular size of the photopolymerizable component and deep, the solvent is not sufficiently separated, and all the droplets containing the photopolymerizable component are absorbed by the pores and the porous layer No photopolymerizable component remains on the surface. In such a case, the printing ink does not adhere to the image area on the surface of the printing plate and printing cannot be performed appropriately. On the other hand, when the pores are relatively shallow, many portions of the droplets are not absorbed by the pores, and the solvent is not sufficiently separated. ) And an image cannot be formed at a necessary resolution. Furthermore, sufficient curing does not occur even when irradiated with ultraviolet rays due to the large amount of solvent present in the attached ultraviolet curable resin.

  When the fine pore size of the anodized layer is slightly larger than the molecular size of the material of the photopolymerizable component and is deep enough to absorb the solvent, the solvent is appropriately separated from the UV curable resin. As a result, only the photopolymerizable component in the ultraviolet curable resin rises in the vicinity of the porous surface, and an optimal ink deposit layer can be formed. For example, when an image pattern is formed at a resolution of 1200 dots / inch, the droplet size of the ultraviolet curable resin needs to be 2 picoliters or less. At this time, the pores of the porous layer formed by the alumite treatment are desirably extremely small pores having a diameter of 100 to 500 mm and a depth of 20 to 25 μm.

  When the recording head 207 moves from one end of the printing original plate 201 to the other end along with the movement of the slider 205 of the linear motor 206 and finishes adhering the ultraviolet curable resin, the linear motor 206 changes direction and follows the stator 204. Thus, the recording head 27 mounted on the slider 205 returns to the original position. During the operation of returning the recording head 207 to the original position, the recording head 207 does not discharge the ultraviolet curable resin, and only the transport mechanism operates. When a new portion (non-imaged area) of the printing original plate 201 is set below the recording head 27 (image forming position) by the insertion roller 292 and the conveyance roller 203, the insertion roller 202 and the conveyance roller 203 are stopped again. . Then, the recording head 207 is moved again from one end of the printing original plate 201 to the other end by the linear motor 206, and the ultraviolet curable resin is attached. As described above, the ultraviolet curable resin is repeatedly attached by the recording head 207 while the printing original plate 201 is intermittently conveyed by the conveyance mechanism.

  The area of the printing original plate 201 where the image formation with the ultraviolet curable resin is completed is then sent to the ultraviolet lamp 208 provided in parallel with the linear motor 206 by the transport mechanism, and the ultraviolet curable resin is irradiated with the ultraviolet curable resin from the ultraviolet lamp 208. Hardens when exposed to light.

  When the attachment and curing of the UV curable resin is completed over the entire surface of the printing original plate 201, the production of the printing plate is completed. Thereafter, the printing plate is set on a normal rotary press, and the necessary number of copies are printed.

  In the above embodiment, the recording head 207 is operated only in the forward path of the reciprocating motion of the slider 205. However, in the backward path of the slider 205, the recording head 207 discharges the ultraviolet curable resin to form an image. It is also possible. In this case, when the forward movement of the slider 205 is completed, only the transport mechanism operates, and after the new portion of the printing original plate 201 is set below the recording head 207 by the insertion roller 202 and the transport roller 203, the insertion roller is again inserted. 202 and the conveyance roller 203 are stopped. By repeating such an operation, the ultraviolet curable resin can be attached and cured over the entire surface of the printing original plate 201.

  The plate making method according to the present invention can provide a printing plate having an image line portion excellent in strength, resolution and oil sensitivity in making a printing plate by an ink jet method, and a film having a negative or positive image from digital information. This is useful as a plate-making method of a lithographic printing plate by an ink jet method capable of directly producing a lithographic printing plate without intervention.

The schematic diagram which shows an example of the image pattern formation process by the plate-making method of this invention The schematic diagram which shows another example of the image pattern formation process by the plate-making method of this invention The figure which shows an example of the plate-making apparatus used for implementation of the plate-making method of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Image forming resin 102, 107 Printing original plate 103 Base material 104 Porous layer 105 Photopolymerizable component 106 Solvent 108 Pore

Claims (12)

A liquid imaging resin containing a plurality of monomers or oligomers that are photopolymerizable components and a solvent that is a non-photopolymerizable component is attached to a printing original plate provided with a water-absorbing and water-resistant porous layer. Forming a desired image pattern, separating the at least part of the solvent from the imaging resin by allowing the solvent to permeate the porous layer, and photopolymerizing the imaging resin. Plate-making method comprising the step of curing by. The plate making method according to claim 1, wherein the image forming resin contains 3 to 50% by weight of a solvent which is the non-photopolymerizable component. The printing original plate comprises a substrate and a water-absorbing and water-resistant porous layer formed by applying inorganic material particles having a plurality of pores having an average diameter of 30 to 500 mm on the substrate together with a water-resistant binder. The plate-making method according to claim 1 or 2, wherein: The plate making method according to claim 3, wherein the inorganic material particles comprise alumina or alumina hydrate and porous silica. The plate making method according to claim 4, wherein the alumina or alumina hydrate is produced by gelation of alumina sol. The plate making method according to claim 5, wherein the alumina or alumina hydrate is pseudo boehmite. The plate making method according to any one of claims 1 to 6, wherein the base material is PET or paper having water resistance treatment on both sides. The said base material has aluminum as a main component, and the said porous layer is an alumite layer which has the thickness of 5 micrometers-50 micrometers provided by anodizing the surface of the base material, or Claim 1 or Claim characterized by the above-mentioned. Item 3. A plate making method according to Item 2. The plate making method according to claim 8, wherein the alumite layer has a large number of pores having a pore diameter of approximately 100 to 500 mm substantially perpendicular to the surface thereof. The plate making method according to any one of claims 1 to 9, wherein the image forming resin has a lipophilic surface after being cured. The plate making method according to any one of claims 1 to 10, wherein the solvent is amphiphilic. The plate making method according to any one of claims 1 to 11, wherein the image forming resin has a viscosity of 4 to 30 centipoise.

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