Lithographic printing plate material and its manufacturing method and printer

[Technical Field to which the Invention Affected] The present invention relates to a reusable lithographic printing plate material, a method for producing the same, and a printing machine.

[Conventional Techniques] In recent years, as printing techniques in general, digitization of printing processes is progressing. This is to digitize the data of images and manuscripts produced by a personal computer or read by a scanner or the like, and directly produce a printing plate material from the digital data. This saves labor in the entire printing process and facilitates high-definition printing.

[0003] Conventionally, as a plate used for printing, a so-called PS plate has an anodic aluminum as a hydrophilic non-image portion and a hydrophobic image portion formed by curing a photosensitive resin on the surface thereof. (Presensitized Plate) has been commonly used. Multiple steps are required to produce a printing plate using this PS plate, which takes time and costs to produce the plate. Therefore, the printing process time is shortened and the printing cost is reduced. It is a difficult situation to promote. Especially in printing a small number of copies, it is a factor of increasing printing cost. In addition, the PS plate requires a developing process using a developing solution, which is not only time-consuming, but also the treatment of the developing waste solution is an important issue from the viewpoint of preventing environmental pollution.

[0004] Further, in the PS plate, a method in which a film on which the original image is perforated is generally brought into close contact with the plate surface and exposed is used, and in order to directly produce a plate from digital data and proceed with digitization of the printing process. The production of printing plates is an obstacle. In addition, after printing one pattern, the plate had to be replaced and the next printing was performed, and the plate was thrown away.

[0005] In response to the above-mentioned drawbacks of the PS plate, some methods have been proposed and commercialized in which the printing process can be digitized and the developing process can be omitted. For example, in Japanese Patent Application Laid-Open No. 63-102936, an ink containing a photosensitive resin is used as an ink for a liquid inkjet printer, the ink is sprayed onto a printing plate material, and then the image portion is cured by light irradiation. A plate-making method characterized by the above is disclosed. Further, Japanese Patent Application Laid-Open No. 11-254633 discloses a method for producing a color offset printing plate by an inkjet head that ejects solid ink.

[0006] Further, a laser absorbing layer such as carbon black is coated on a PET (polyethylene terephthalate) film, and a silicon resin layer is coated on the laser absorbing layer, and an image is written on the PET (polyethylene terephthalate) film to generate heat of the laser absorbing layer. A method of producing a printing plate by burning off a silicon resin layer by heat, or a method of applying an oil-based laser absorption layer on an aluminum plate and then applying a hydrophilic layer on the coating with a laser beam in the same manner as described above. There are known methods such as burning off to make a printing plate.

[0007] In addition to this, a means for producing a plate by using a hydrophilic polymer as a plate material and lipophilicizing the irradiated portion by image exposure has also been proposed. Furthermore, a method of writing an image directly from digital data to a PS plate with light has also been proposed. For example, a writing device using a 405 nm blue laser or a writing device using a micromirror and a UV lamp, so-called CTP (Computer To Plate). Is commercially available.

[0008] [Problems to be Solved by the Invention] However, although it is possible to produce a plate directly from digital data by the above method, it is necessary to replace it with a new plate after printing one pattern. If so, the next printing cannot be performed, and therefore the plate once used is still discarded.

[0009] On the other hand, a technique including reproduction of a plate has also been proposed. For example, in Japanese Patent Application Laid-Open No. 10-250027, a method for producing a latent image block copy and a latent image block copy using a titanium oxide photocatalyst, and a printing apparatus having a latent image block copy are also described in JP-A-11-147360. The publication also discloses an offset printing method using a block copy using a photocatalyst , all of which use light that activates the photocatalyst for image writing, that is, substantially ultraviolet rays, and heat-treat the photocatalyst. A method of hydrophobizing and regenerating the plate has been proposed. Further, in the method for producing a lithographic printing plate disclosed in Japanese Patent Application Laid-Open No. 11-105234, a method of hydrophilizing a photocatalyst with active light, that is, ultraviolet rays, and then drawing an image portion by heat mode drawing has been proposed. ..

However, it has been confirmed by Professor Fujishima and Professor Hashimoto of the University of Tokyo that the titanium oxide photocatalyst becomes hydrophilic by heat treatment [Mitsube et al. Research , 5th Symposium of Photocatalytic Materials Study Group Recent Developments of Photocatalytic Reactions , (1998) p.124-125], according to the methods disclosed in each of the above publications, that is, heating. It is not possible to regenerate the plate by hydrophobizing the photocatalyst by the treatment, which means that it is impossible to recycle the plate or prepare the plate by this method.

[0011] On the other hand, the present inventors can quickly write an image on a plate material with a writing device using active light having an energy larger than the band gap energy of the photocatalyst, and quickly after printing. We have conducted diligent research on a plate material that can be recycled and reused, a method for producing this plate material, and a method for regenerating a printing plate. According to this research, it is necessary to make the surface of the plate material hydrophilic when writing an image on the plate material or erasing the image data when playing back the plate. An important issue is how to quickly hydrophilize with weaker light.

[0012] As a technique related to such photo-induced hydrophilization (hereinafter referred to as hydrophilization), Irie et al. "TiO"₂/ WO₃"Study on the effect of the hydrophilicity property of the laminated interface" [Photocatalytic Materials Research Group 8th Symposium "Recent Development of Photocatalytic Reactions", (2001) p.44-45]₃(Tungsten oxide) TiO on thin film₂A technique for increasing the sensitivity of photocatalytic activity, particularly photoinduced hydrophilicity, by laminating a (titanium oxide) thin film has been disclosed.

[0013] By the way, according to a recent study, it is considered that holes contribute to the hydrophilization of titanium oxide. That is, the above-mentioned high sensitivity of hydrophilization is TiO.₂And WO₃By combining with, TiO by irradiation with active light₂The electrons generated inside are WO₃By migrating to TiO₂Increases the efficiency of charge separation (preventing electron and hole recombination) and WO₃The holes generated inside are TiO₂It is thought that this is achieved by being supplied to.

[0014] Therefore, if such a technique is applied to a printing plate material, the hydrophilicity of the photosensitive layer can be made highly sensitive (that is, the energy for making the photosensitive layer can be reduced), and the plate material can be converted to a plate material with weaker light. It is possible to write the image of the above, and it is possible to shorten the image writing time and the plate reproduction time on the plate material, but further reduction of these is required in order to speed up the printing process.

[0015] The present invention has been devised in view of the above-mentioned problems, so that the plate can be regenerated and used repeatedly, and the image writing time and the plate reproduction time in the printing process can be further shortened. It is an object of the present invention to provide a plate material for lithographic printing, a method for producing the same, and a printing machine.

[Means for Solving the Problems] As a result of further diligent research focusing on the improvement of charge separation efficiency, the present inventors have conducted a layer containing a photocatalyst (photosensitive layer) and two or more types of oxides. It has been found that by compounding a layer made of a semiconductor, it is possible to make the photosensitive layer hydrophilic and to further increase the sensitivity of the organic matter decomposition reaction.

That is, the lithographic printing plate material (claim 1) of the present invention is:<u style="single">Titanium oxide photocatalyst or titanium oxide photocatalyst processed product</u>An image can be written by active light having a layer containing a photocatalyst and having an energy larger than the band gap energy of the photocatalyst, and a plate can be produced without a wet development process, and the plate can be repeatedly reproduced and used. A plate material for lithographic printing, which is provided between a base material, a photosensitive layer provided on the surface of the base material and containing the photocatalyst that reacts with the active light, and the base material and the photosensitive layer. ,<u style="single">With tungsten oxide and tin oxide</u>It is characterized in that it is composed of an intermediate layer that includes and improves the charge separation efficiency of the photosensitive layer. Hereinafter, light having effective energy for expressing catalytic activity in the photocatalyst of the present invention will be referred to as active light.

[0018] The photocatalyst is a titanium oxide photocatalyst or a processed titanium oxide photocatalyst.<u style="single">。</u> Here, the titanium oxide photocatalyst processed product is a product obtained by doping or supporting an element (metal element or non-metal element) other than the element originally contained in the titanium oxide photocatalyst based on the titanium oxide photocatalyst, or a titanium oxide photocatalyst. It refers to the ratio of the Ti element and the O element shifted from the ratio of the chemical quantity theory, that is, the ratio of the oxygen atom 2 to the Ti atom 1. Normally, when the titanium oxide photocatalyst has, for example, anatase-type crystals, the bandgap energy is 3.2 eV, and light having a wavelength of 380 nm or less is active light. It is possible to reduce the bandgap energy and use light having a wavelength of 600 nm or less as active light.

[0019] The intermediate layer is made of tungsten oxide (particularly WO).₃) And tin oxide (especially SnO)₂) And<u style="single">。</u>By including these two types of oxide semiconductors, as compared with the case where these oxide semiconductors are not contained or when only one of these oxide semiconductors is contained, the above-mentioned photocatalyst has a hydrophilic action and the photocatalyst is organic. Both actions, both actions of degrading the compound, are activated.

[0020] The mixing ratio of the tungsten oxide and the tin oxide is WO, respectively.₃And SnO₂It is preferable that the weight ratio is 1: 1 (claim).<u style="single">2</u>). The active light is preferably light having a wavelength of 600 nm or less (claim).<u style="single">3</u>). It is preferable that the characteristics of the surface of the photosensitive layer are converted between hydrophilicity and hydrophobicity when the image is written on the plate material and when the plate is regenerated (claim).<u style="single">4</u>)。

[0021] It is preferable that the characteristics of the surface of the photosensitive layer are changed from hydrophobic to hydrophilic when irradiated with the active light (claim).<u style="single">5</u>). That is, by irradiating the surface of the plate material with active light, the irradiated surface can be converted into hydrophilic. This is because the photocatalyst is hydrophilic when the surface of the photosensitive layer is made hydrophobic by using a hydrophobic organic compound having a property of being decomposed by the action of the photocatalyst to be hydrophilic or by the action of the photocatalyst as described later. This is due to both the action of forming and the action of decomposing organic compounds. Then, the plate surface converted to hydrophilic functions as a non-image area to which dampening water adheres preferentially and hydrophobic ink does not adhere. On the other hand, the plate surface not irradiated with the active light is hydrophobic, and the hydrophobic ink preferentially adheres to the plate surface, and the plate surface functions as an image area to which the dampening water does not adhere.

[0022] During regeneration of the above plate, a hydrophobic organic compound having a property of being decomposed by the action of the photocatalyst when irradiated with the active light is supplied to the surface of the photosensitive layer, and the photosensitive layer is exposed to light. It is preferable that the surface of the photosensitive layer is made hydrophobic by either irradiating the surface of the layer with an energy bundle of light or electricity and applying friction to the surface of the photosensitive layer (claim).<u style="single">6</u>)。

[0023] A method for producing a plate material for lithographic printing according to the present invention (claim).<u style="single">7</u>) Has a layer containing a photocatalyst, an image is written by active light having an energy larger than the bandgap energy of the photocatalyst, a plate can be produced without a wet development process, and the plate is repeatedly regenerated and used. It is a method for producing a plate material for lithographic printing, which is possible on the surface of a base material.<u style="single">With tungsten oxide and tin oxide</u>It is characterized in that it includes an intermediate layer forming step of forming an intermediate layer including the above and improving charge separation efficiency, and a photosensitive layer forming step of forming a photosensitive layer containing the photocatalyst on the surface of the intermediate layer.

[0024] The intermediate layer forming step is<u style="single">Tungsten oxide and tin oxide on the surface of the base material</u>After applying the sol solution containing<u style="single">With tungsten oxide and tin oxide</u>It is a step of curing the sol liquid containing the photocatalyst, and the photosensitive layer forming step is preferably a step of applying the sol liquid containing the photocatalyst and then curing the sol liquid containing the photocatalyst (claim 8). .. The intermediate layer forming step is described above.<u style="single">Tungsten oxide and tin oxide</u>By sputtering using the target of<u style="single">With the above tungsten oxide and tin oxide</u>It is a step of forming a layer containing the photocatalyst on the surface of the base material, and the step of forming the photosensitive layer is preferably a step of forming a layer containing the photocatalyst by sputtering using a target containing the photocatalyst and then firing. Claim 9).

【0025】<u style="single">Book</u>Printing press of the invention (Claim 1)<u style="single">0</u>) Is a claim<u style="single">6</u>An image obtained by irradiating the plate cylinder to which the above-mentioned planographic printing plate material is attached, the plate surface hydrophobizing device for hydrophobizing the plate material surface, and the above-mentioned hydrophobized plate material surface with active light having a wavelength of 600 nm or less. An image writing device for writing an image, an inking roller for applying ink to the surface of the plate on which the above image was written, a plate cleaning device for removing the ink applied on the surface of the plate, and after removing the ink. The plate material surface is provided with an image history erasing device that hydrolyzes the plate material surface by irradiating the plate material surface with the active light to erase the image history of the plate material surface.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a plate material for lithographic printing according to an embodiment of the present invention, FIG. 1 is a schematic cross-sectional view when the surface of the plate material shows hydrophobicity, and FIG. 2 is a schematic cross-sectional view. It is a schematic cross-sectional view when the surface of the plate material shows hydrophilicity.

As shown in FIG. 1, the planographic printing plate material 5 is basically composed of a base material 1, an intermediate layer 2, and a photosensitive layer 3. The lithographic printing plate material 5 is also simply referred to as a plate material, and a plate material having an image line portion for printing formed on the surface thereof is referred to as a plate. The base material 1 is made of a metal such as aluminum or stainless steel, a polymer film, or the like. However, the present invention is not limited to metal or polymer films such as aluminum and stainless steel.

[0028] The photosensitive layer 3 is configured to include a titanium oxide photocatalyst. The surface of the photosensitive layer 3 is irradiated with active light having an energy higher than the band gap energy of the photocatalyst to decompose organic compounds adhering to the surface of the photosensitive layer 3 and to exhibit high hydrophilicity. And are expressed at the same time.

[0029] Originally, a photocatalyst does not exhibit the photocatalytic activity unless it is irradiated with active light. For example, the anatase-type titanium oxide photocatalyst has a bandgap energy of 3.2 eV, so it responds only to ultraviolet rays with a wavelength of 380 nm or less. In this embodiment, a photocatalyst that responds to light having a wavelength of 600 nm or less by forming a new level in this band gap is used. Ultraviolet rays are also included in the light having a wavelength of 600 nm or less, but the photocatalyst of the present embodiment is characterized in that it responds in the same manner regardless of whether or not the active light contains ultraviolet rays. ..

[0030] As a method for producing a photocatalyst that also reacts with light in the visible light region, a known method may be used. For example, Japanese Patent Application Laid-Open No. 2001-207082 discloses a visible light responsive photocatalyst doped with a nitrogen atom, and Japanese Patent Application Laid-Open No. 2001-205104 discloses a visible light responsive photocatalyst doped with a chromium atom and a nitrogen atom. Has been done. Further, Japanese Patent Application Laid-Open No. 11-197512 discloses a visible light responsive photocatalyst in which metal ions such as chromium are ion-implanted. In addition, a visible light responsive photocatalyst using low temperature plasma and a platinum-supported visible light responsive photocatalyst have been published. In producing the planographic printing plate material 5 according to the present embodiment, a visible light responsive photocatalyst (titanium oxide photocatalyst processed product) produced by these known methods may be used.

[0031] Further, the photosensitive layer containing the visible light responsive photocatalyst (note that the photosensitive layer is also referred to as a photocatalyst layer because it contains a photocatalyst) 3 maintains the above-mentioned properties and hydrophilic properties, or is photosensitive with the base material 1. The following substances may be added for the purpose of improving the adhesion to the layer 3 and the strength of the photosensitive layer 3. For example, silica-based compounds such as silica, silica sol, organosilane, and silicon resin, metal oxides or metal hydroxides such as zirconium, aluminum, and titanium, and fluorine-based resins can be mentioned.

[0032] Titanium oxide photocatalysts include rutile type, anatase type, and brookite type, all of which can be used in the present embodiment, and a mixture thereof may be used, but in consideration of photocatalytic activity, crystals The anatase type, which has the highest structural activity, is preferable. Further, as will be described later, in order to increase the photocatalytic activity of decomposing the image area under the above-mentioned irradiation with active light, it is preferable that the particle size of the titanium oxide photocatalyst is small to some extent. Specifically, the particle size of the titanium oxide photocatalyst is preferably 0.1 μm or less, more preferably 0.05 μm or less. The titanium oxide photocatalyst is suitable as the photocatalyst, but of course, the photocatalyst is not limited to this.

[0033] Further, the film thickness of the photosensitive layer 3 is preferably in the range of 0.005 to 1 μm. The reason for this is that if the film thickness is too small, it is difficult to make full use of the above-mentioned properties, and if the film thickness is too large, the photosensitive layer 3 is easily cracked, which causes a decrease in printing durability. is there. Since this crack is remarkably observed when the film thickness exceeds 10 μm, it is necessary to recognize 10 μm as the upper limit even if the above range is relaxed. In practice, the film thickness is more preferably about 0.03 to 0.5 μm.

[0034] Further, an intermediate layer 2 is formed between the base material 1 and the photosensitive layer 3. By including two or more types of oxide semiconductors as the intermediate layer 2, the present inventors have an action of making the photocatalyst itself contained in the photosensitive layer 3 hydrophilic under activation light irradiation, and the photocatalyst is an organic compound. It was found that the action of decomposition can be improved at the same time.

[0035] That is, one of the features of the planographic printing plate material 5 according to the present embodiment is that the intermediate layer 2 contains two or more types of oxide semiconductors, and in the present embodiment, the intermediate layer is contained. (Since the intermediate layer contains an oxide semiconductor, it is also called an oxide layer.) 2 is composed of tungsten oxide and tin oxide. Tungsten trioxide (WO₃), Tin oxide (SnO)₂), Chromium oxide (Cr₂O₃), Vanadium oxide (V)₂O₅), Molybdenum oxide (MoO)₃), Antimony oxide (Sb₂O₃), Iron oxide (Fe₂O₃), Copper oxide (Cu₂O), niobium oxide (Nb)₂O₅) And the like, two or more types of oxide semiconductors may be appropriately selected and used. Further, the two or more types of oxide semiconductors are not limited to these.

[0036] It is not clear why the intermediate layer 2 containing two or more types of oxide semiconductors is effective in improving the photocatalytic action, but probably holes and electrons generated in the photocatalyst by activation light irradiation. It is presumed that this is because the recombination with and is suppressed and the charge separation efficiency between holes and electrons is increased.

[0037] Further, when the base material 1 is a polymer film or the like, the intermediate layer 2 has an effect of protecting the base material 1. Further, when heat treatment is performed for forming the photosensitive layer 3 described later, there is also an effect of preventing impurities from being thermally diffused from the base material 1 and mixed into the photosensitive layer 3 to reduce the photocatalytic activity. ..

[0038] Further, as a method for forming the intermediate layer 2, a sol coating method, an organic titanate method, a sputtering method, a CVD method, a PVD method and the like may be appropriately selected and formed, and among these, the sol coating method is particularly suitable. Is preferable because the step of forming the intermediate layer 2 containing two or more kinds of oxides is simple. If the sol coating method is adopted, the sol coating liquid used for the sol coating liquid contains the above-mentioned various substances that improve the strength of the titanium oxide photocatalyst and the photosensitive layer 3 and the adhesion between the base material 1 and the photosensitive layer 3. In addition, a solvent, a cross-linking agent, a surfactant and the like may be added. The sol coating liquid may be a room temperature drying type or a heat drying type, but the latter is more preferable. The reason for this is that increasing the strength of the photosensitive layer 3 by heating is advantageous for improving the printing durability of the plate material 5.

[0039] When the intermediate layer 2 and the photosensitive layer 3 are formed by the sol coating method, first, a sol solution containing an oxide semiconductor is applied to the surface of the base material 1, and then the sol solution is cured to cure the intermediate layer 2. (Intermediate layer forming step). Then, a sol solution containing a photocatalyst is applied to the surface of the intermediate layer 2, and then the sol solution is cured to form the photosensitive layer 3 (photosensitive layer forming step).

[0040] Further, for example, the intermediate layer 2 is formed on the surface of the base material 1 by a sputtering method using two or more kinds of oxide targets (intermediate layer forming step), and the intermediate layer 2 is intermediated by sputtering using a target containing a photocatalyst. The photosensitive layer 3 may be formed on the surface of the layer 2 and then fired (photosensitive layer forming step). As a result, the film strength of the plate material 5 can be increased, and high printing resistance can be obtained.

[0041] In addition, on the layer (photosensitive layer) 3 containing a photocatalyst that responds to active light in the present invention, that is, light having a wavelength of 600 nm or less, a layer containing a photocatalyst that responds to light having a wavelength of 380 nm or less is protected. Or a silica layer may be provided for the purpose of facilitating the maintenance of hydrophilicity. Further, the photosensitive layer 3 in the present embodiment may have the above-mentioned layer.

[0042] Next, a method for producing and a method for reproducing the plate according to the present embodiment will be described. As shown in FIG. 3, the flow of plate preparation and regeneration includes a hydrophobization step (step S100), an image writing step (non-image writing step) (step S110), a printing step (step S120), and an ink removing step. (Step S130), hydrophilization step (image history erasing step) (step S140).

[0043] First, a method for producing a plate will be described. In the following, "making a plate" means that at least a part of the surface of the plate 5 is based on digital data from the state where the surface of the plate 5 (that is, the surface of the photosensitive layer 3) is hydrophobized (initial state). By irradiating light with a wavelength equal to or less than visible light (active light) to form a hydrophilic non-image area, the plate surface is combined with the hydrophobic part on the surface of the plate material 5 that was not irradiated with active light. It refers to forming a latent image consisting of a hydrophobic image portion and a hydrophilic non-image portion.

[0044] First, as shown in FIG. 4A, in the hydrophobization step, the surface of the photosensitive layer 3 whose entire surface has been hydrophilized in the previous step (hydrophilization step) is hydrophobized. Here, as a method for making the surface of the photosensitive layer 3 hydrophobic, a hydrophobic organic compound having a property of being decomposed by the action of a photocatalyst when irradiated with active light is supplied to the surface of the photosensitive layer 3 and Either one of irradiating the surface of the photosensitive layer 3 with an energy bundle such as light or electricity alone or in combination of a plurality of energy bundles, or applying mechanical energy such as friction to the surface of the photosensitive layer 3 can be used.

[0045] FIG. 4A shows an initial state in which the entire surface of the plate material 5 is hydrophobized. Here, the hydrophobic plate material 5 surface is a plate material 5 surface having a contact angle of water 6 of 50 ° or more, preferably 80 ° or more, and hydrophobic ink for printing easily adheres to the surface, while the hydrophobic ink for printing easily adheres to the surface. Adhesion of dampening water is difficult. Further, this state of the surface of the photosensitive layer 3 is referred to as "initial state at the time of plate making". This "initial state at the time of plate making" may be regarded as the start time in the actual printing process. More specifically, it can be regarded as referring to the state when digitized data of an arbitrary image is already prepared and it is attempted to be written on the surface of the plate material 5.

Then, as shown in FIG. 4B, in the image writing step, a non-image portion is written on the surface of the photosensitive layer 3 which is in a hydrophobic state. This non-image area is written on the surface of the photosensitive layer 3 so as to correspond to the digital data related to the image. Here, as shown in FIG. 2, the non-image area is a hydrophilic part where the contact angle of water 6 is 10 ° or less, and dampening water easily adheres to it, while printing ink adheres to it. Is in a difficult state.

[0047] As a method for revealing this hydrophilic non-image area based on image data, the photosensitive layer 3 containing light having a wavelength of 600 nm or less, that is, a photocatalyst that exhibits catalytic activity by active light, is irradiated with active light. Then, the surface of the photosensitive layer 3 is made hydrophilic by the action of the photocatalyst. On the other hand, since the surface of the photosensitive layer 3 that has not been irradiated with the active light remains hydrophobic, a hydrophilic portion and a hydrophobic portion are formed on the surface of the plate material 5, and a plate can be produced.

[0048] Here, as shown in FIG. 4B, a non-image portion is written by a writing head using visible light, for example, a violet laser having a wavelength of 405 nm, and the non-image portion is drawn on the surface of the hydrophobic photosensitive layer 3. I try to form a part. In addition to the writing head using a violet laser with a wavelength of 405 nm, for example, a UV setter announced by Basis Print Co., Ltd. (Germany) is used as a method for displaying a hydrophilic non-image area based on image data. An image can be written using active light, such as a writing head using a light source that generates light having a wavelength of 360 nm to 450 nm and a micromirror used in the 710.

When the above image writing step is completed, as shown in FIG. 4C, an image area portion and a non-image area portion are formed on the surface of the photosensitive layer 3, and printing is possible. .. In this printing process, so-called emulsifying ink, which is a mixture of dampening water and hydrophobic ink for printing and dampening water, is applied to the surface of the plate material 5. Therefore, for example, when an image as shown in FIG. 5 is written, the shaded portion (that is, the hydrophobic image portion) 3b shows a state in which the hydrophobic ink is attached. The remaining white background (that is, the hydrophilic non-image area) 3a shows a state in which the dampening water preferentially adheres, while the hydrophobic ink is repelled and does not adhere. When the image (picture) emerges in this way, the surface of the photosensitive layer 3 has a function as a plate. After that, a normal printing process, that is, printing on paper is performed, and printing is completed.

[0050] Next, a method of reproducing the printing plate will be described. In the following, "regeneration of the plate" means that the surface of the plate material 5 in which at least a part is hydrophobic and the remaining part is hydrophilic is uniformly hydrophilic on the entire surface, and then activated light is irradiated. To supply the surface of the plate 5 with an organic compound having the property of being decomposed by the action of a photocatalyst, and to irradiate the surface of the plate 5 with one or a plurality of energy bundles such as light and electricity. By applying mechanical energy such as friction to the surface of the photosensitive layer 3 to the surface of the plate material 5, the photocatalytic properties are converted from hydrophilic to hydrophobic and restored to the "initial state at the time of plate preparation". It shall be said.

[0051] First, as an ink removing step, ink, dampening water, paper dust, etc. adhering to the surface of the plate material 3 after printing is removed. The removal method includes a method of stopping the supply of ink to the surface of the plate 5 to reduce printing, a method of wiping the ink with a mechanism for winding the cloth-like tape for wiping ink, and a roller around which the cloth-like material for wiping ink is wound. A method of wiping off the ink with a cloth, a method of spraying a cleaning liquid with a spray to clean the ink, and the like may be appropriately used.

After that, in the hydrophilization step, as shown in FIG. 4 (e), by irradiating the entire surface of the photosensitive layer 3 with active light, the image line portion 3b is also hydrophilized, and the entire surface of the photosensitive layer 3 is water 6 Can be a hydrophilic surface with a contact angle of 10 ° or less. That is, the entire surface of the photosensitive layer 3 can be brought into the state shown in FIG. 2, and the entire image history can be erased. The property that the hydrophobic image portion existing on the surface of the photosensitive layer 3 is converted into a surface having high hydrophilicity by irradiating with active light can be achieved by using, for example, a titanium oxide photocatalyst. it can. Here, as shown in FIG. 4 (e), the hydrophobic image portion is converted to hydrophilic by ultraviolet irradiation, the entire surface of the photosensitive layer 3 is made hydrophilic, and the plate history is erased by using an ultraviolet lamp. Shows the case.

[0053] Further, at this time, the surface of the photosensitive layer 3 may be heated at the same time as the irradiation of the active light on the surface of the photosensitive layer 3. As a result, when the surface of the photosensitive layer 3 is made hydrophobic using the above-mentioned organic compound, the decomposition reaction of the organic compound on the surface of the photosensitive layer 3 can be accelerated and the reaction can be performed in a short time. As the heating method at this time, hot air blowing or light irradiation for heating the surface of the photosensitive layer 3 is preferable. Here, as the light to be irradiated, infrared rays are more preferable in consideration of heating efficiency.

[0054] Then, in the hydrophobization step, the surface of the plate 5 is irradiated with energy bundles such as light and electricity alone or in combination of two, and mechanical energy such as friction is applied to the surface of the plate 5. , The photocatalytic property is changed from hydrophilic to hydrophobic by supplying a hydrophobic organic compound to the surface of the plate material 5, and the initial state at the time of plate preparation is returned.

The hydrophilization step is added as one of the steps in order to completely eliminate the history of the plate, but in the ink removal step, the ink adhering to the surface of the plate material 5 is at least for the next printing. If it is sufficiently removed to the extent that it does not affect it, it is permissible to skip this hydrophilization step and directly move from the ink removal step to the hydrophobization step.

[0056] The graph shown in FIG. 6 summarizes what has been described above. This is a graph in which the horizontal axis represents time or operation and the vertical axis represents the contact angle of water 6 on the surface of the plate material 5, and the water on the surface of the photosensitive layer 3 with respect to the plate material 5 for lithographic printing in the present embodiment. It shows how the contact angle of 6 changes with time or operation. In FIG. 6, the alternate long and short dash line indicates the contact angle of the non-image portion 3a of the photosensitive layer 3, and the solid line indicates the contact angle of the image portion 3b.

[0057] First, the surface of the photosensitive layer 3 is irradiated with active light so that the contact angle of water 6 on the surface of the photosensitive layer 3 exhibits high hydrophilicity of 10 ° or less. Then, as a hydrophobizing step (step A shown in FIG. 6), the surface of the plate material 5 is irradiated with energy bundles such as light and electricity individually or in combination, and mechanical energy such as friction is applied to the plate material. The photocatalytic property is changed from hydrophilic to hydrophobic by either adding it to the surface of 5 or supplying a hydrophobic organic compound to the surface of the plate material 5. That is, the contact angle of water 6 on the surface of the plate 5 is 50 ° or more, preferably 80 ° or more. The time point when the hydrophobization treatment is completed [time point (b) in FIG. 6] is the initial state at the time of plate preparation.

Next, as an image writing step (step B shown in FIG. 6), writing of a non-image portion on the surface of the hydrophobic photosensitive layer 3 with active light is started [time point (b) in FIG. 6). ]. As a result, the surface of the photosensitive layer 3 irradiated with the active light is converted from hydrophobic to hydrophilic by the action of the photocatalyst. That is, the contact angle of the water 6 of the photosensitive layer 3 is 10 ° or less. On the other hand, since the surface of the photosensitive layer 3 not irradiated with the active light remains in a hydrophobic state, the portion of the surface of the photosensitive layer 3 not irradiated with the active light becomes a hydrophobic image portion, and the portion irradiated with the active light is not hydrophilic. Since it becomes an image part, it can function as a plate.

Then, after the writing of the non-image area is completed, printing is started as a printing step (step C shown in FIG. 6) [time point (c) in FIG. 6]. After printing is completed, as an ink removing step (step D shown in FIG. 6), ink, stains, etc. on the surface of the photosensitive layer 3 are removed [time point (d) in FIG. 6]. After the ink removal is completed, as a hydrophilization step (step E shown in FIG. 6), activation light irradiation to the surface of the photosensitive layer 3 is started [time point (e) in FIG. 6]. As a result, the hydrophobic image portion is converted into hydrophilic by the action of the photocatalyst, and the entire surface of the photosensitive layer 3 returns to hydrophilic again.

[0060] After that, as the next hydrophobizing step (step A'shown in FIG. 6), the surface of the plate 5 is irradiated with energy fluxes such as light and electricity alone or in combination of two, and friction and the like. By either applying the mechanical energy of the above to the surface of the plate 5 or supplying a hydrophobic organic compound to the surface of the plate 5 [point in FIG. 6 (a')], "plate preparation". It is possible to return to the "initial state of time" and reuse the plate material 5.

[0061] In order to perform the above printing and plate reproduction on the printing machine, it is preferable to use the printing machine 10 as shown in FIG. 7. The printing machine 10 has a plate cleaning device 12, an image writing device 13, a plate surface hydrophobizing device 14, a heating device 15, and an active light irradiation for hydrophilic treatment as an image history erasing device around the plate cylinder 11. It is equipped with a device 16, an inking roller 17, a dampening water supply device 18, and a blanket body 19. The plate material 5 is wound around the plate cylinder 11 and installed.

Hereinafter, the reproduction and production of the plate will be described with reference to FIG. 7. First, the plate cleaning device 12 is in contact with the plate cylinder 11, and the ink and dampening water adhering to the surface of the plate material 5 are provided. Wipe off paper dust etc. cleanly. FIG. 7 shows a plate cleaning device 12 having a mechanism for winding a cloth-like tape for wiping ink, but the present invention is not limited to this.

[0063] After that, the plate cleaning device 12 is detached from the plate cylinder 11, and the entire surface of the plate material 5 is irradiated with active light by the active light irradiation device 16 for hydrophilization treatment while the surface of the plate material 5 is heated by the heating device 15. Plate material 5 Make the entire surface hydrophilic. Here, ultraviolet rays having a wavelength of 380 nm or less are used as the active light, but when the photocatalyst exhibits activity even with light having a wavelength of 400 nm to 600 nm, light having a wavelength of 400 nm to 600 nm may be used.

[0064] Then, the entire surface of the plate material 5 is hydrophobized by the hydrophobizing device 14 on the plate surface. Note that FIG. 7 shows the plate surface hydrophobizing device 14 as a device for supplying a hydrophobic organic compound by a roller, but the present invention is not limited to this, and of course, energy bundles such as light and electricity can be supplied. It may be configured as a device for irradiating the plate material 5 alone or in combination, or as a device for applying mechanical energy such as friction to the surface of the plate material 5.

Next, based on the digital data of the image prepared in advance, the image writing device 13 irradiates the surface of the plate material 5 with active light to write the non-image portion 3a (that is, the image is written on the surface of the plate material 5). Write). As the active light of the image writing device 13, light having a wavelength of 600 nm or less can be used. After writing the image, the inking roller 17, the dampening water supply device 18, and the blanket cylinder 19 are brought into contact with the plate cylinder 11, and the paper 20 is brought into contact with the blanket cylinder 19. Then, by rotating in the directions of the arrows shown in FIG. 7, dampening water and ink are sequentially supplied to the surface of the plate material 5, and printing is performed on the paper 20.

[0066] As described above, in the printing machine 10, the plate cleaning device 12 for cleaning the surface of the plate material 5 attached to the plate cylinder 11 and the image area are erased (image history erasure) by irradiation with active light. The active light irradiation device 16 for hydrophilization treatment, the hydrophobic device 14 that hydrophilizes the surface of the plate material 5, and the heating device 15 that heats the surface of the plate material 5 to promote hydrophilization are the regeneration devices that regenerate the plate. Further, by providing an image writing device 13 for writing an image on the surface of the plate material 5, a series of plates can be reproduced and produced with the plate material 5 attached to the plate cylinder 11 of the printing machine 10. Can be performed. According to this, it is possible to carry out continuous printing work without stopping the printing machine 10 and without interposing the replacement work of the plate material 5.

[0067] Further, since light having a wavelength of 600 nm or less is used when writing an image, it is possible to write an image with light that is easier to handle. The printing machine 10 is configured to wind the plate material 5 around the plate cylinder 11, but the present invention is not limited to this, and the photosensitive layer 3 containing a photocatalyst is provided directly on the surface of the plate cylinder 11. That is, it goes without saying that a plate cylinder 11 and a plate material 5 may be integrally configured.

[0068] Next, regarding the method for producing the plate material and the method for regenerating the plate according to the present embodiment, more specific examples in which the inventors of the present application have confirmed the procedure for producing the plate material and the plate regeneration and the effect thereof. I will explain it.

&lt;Catalyst Preparation&gt; Ammonia water was added to titanium sulfate (Wako Pure Chemical Industries, Ltd.) as a raw material with stirring to obtain a hydrolyzate of titanium sulfate. The hydrolyzate was filtered through Nutche and washed with ion-exchanged water until the electrical conductivity of the filtrate was 2 μS / cm or less. After washing, the hydrolyzate was dried at room temperature and then calcined in the air at 400 ° C. for 2 hours. This fired product was first crushed in a mortar to obtain a photocatalyst powder.

[Confirmation of Visible Light Activity&gt; 0.2 g of the photocatalyst powder was collected and spread uniformly on the bottom of a sealed Pyrex (R) glass cylindrical container (capacity: 500 mL). Then, the inside of the reaction vessel was degassed and then replaced with high-purity air. Then, acetone was injected so that the concentration in the reaction vessel became 500 ppm, and then adsorbed at 25 ° C. for 10 hours in a dark place until the adsorption parallel was reached. After that, it irradiates Nichia's blue LED (main wavelength 470 nm) with acetone and CO.₂As a result of tracking the amount with a Shimadzu gas chromatograph, acetone disappeared after 20 hours of blue LED irradiation, and instead, CO that matches the chemical quantity ratio of acetone.₂Was confirmed to occur. That is, it was confirmed that the photocatalytic powder exhibits catalytic activity with light having a wavelength of 470 nm.

&lt;Preparation of Plate Material&gt; (a) A base material 1 made of stainless steel (SUS301) having a prepared area of 280 × 204 mm and a thickness of 0.1 mm was prepared and subjected to alkaline degreasing treatment to obtain a plate material substrate. (b) Intermediate layer formation Ammonium paratungstate (Wako Pure Chemical Industries, Ltd.) was dissolved in a 10 wt% aqueous solution of methylamine (Wako Pure Chemical Industries, Ltd.) to prepare an ammonium paratungstate solution. WO of the ammonium paratungate solution and the transparent conductive material Ceramece S-8 (manufactured by Taki Chemical Co., Ltd., 8 wt% aqueous solution of tin oxide ultrafine particles) by weight₃/ SnO₂The mixture was mixed at a ratio of = 1/1 to prepare an intermediate layer coating liquid. This intermediate layer coating liquid was dip-coated on the plate material substrate 1, air-dried, and then fired at 500 ° C. for 1 hour to form the intermediate layer 2. The thickness of the intermediate layer 2 at this time was about 0.12 μm.

(C) Formation of Photosensitive Layer The photocatalyst powder was dispersed in ion-exchanged water to prepare a slurry having a solid content of 20% by weight. This slurry was pulverized with a wet mill (trade name: Dynomill PILOT) to prepare a photocatalyst dispersion. Then, in the photosensitive layer forming step, TKC-301, a titanium oxide coating agent manufactured by TAYCA Corporation, was added to the photocatalyst dispersion.₂The liquid mixed at a weight ratio of 6: 4 was dip-coated on the plate material substrate, air-dried, and then fired at 350 ° C. for 1 hour to form the photosensitive layer 3 to obtain the plate material 5. The thickness of the photosensitive layer 3 at this time was about 0.1 μm. When the contact angle of water 6 was measured on the surface of the plate 5 with a CA-W type contact angle meter manufactured by Kyowa Interface Science, the contact angle was 8 °, showing sufficient hydrophilicity.

[Hydrophelicization of plate surface&gt; Next, 1,2-epoxy dodecane (Wako Pure Chemical Industries, Ltd.) was dissolved in isoparaffin (trade name: Isopar L, manufactured by ExxonMobil) to prepare a 1 wt% solution. This 1,2-epoxy dodecane solution was roll-coated on the surface of the plate 5 and dried at 60 ° C. for 10 minutes. After that, when the contact angle of water 6 was measured with a contact angle meter, the contact angle was 83 °, showing sufficient hydrophobicity, and it was confirmed that the surface of the plate material 5 was in the initial state at the time of plate preparation.

&lt;Image writing&gt; Next, an image writing device using a semiconductor laser having a wavelength of 405 nm, an output of 5 mW / channel, and a beam diameter of 15 μm is used to cut the image on the surface of the plate 5 in 10% increments of 10% to 100%. I wrote a halftone dot image of. When the contact angle of water 6 on the surface of the plate 5 after writing was measured with a contact angle meter, the contact angle was 8 ° for the part written with the semiconductor laser, which was a hydrophilic non-image area, and the part not written was not written. It was confirmed that the image area maintained the hydrophobicity with a contact angle of 83 °.

[Printing&gt; This plate material 5 is attached to the desktop offset printing machine New Ace Pro of Alpha Giken Co., Ltd., and is combined with Toyo Ink's ink (HYECOOB Beni MZ) and Mitsubishi Heavy Industries' dampening water lithofero 1% solution. Printing was started on iBest paper at a printing speed of 3500 sheets / hour. A halftone dot image could be printed on the paper from the first sheet of printing.

[Regeneration&gt; Next, an embodiment relating to regeneration of the printing plate material 5 will be described. After printing, the ink, dampening water, paper dust, etc. adhering to the surface of the plate material 5 were wiped off cleanly, and the entire surface of the plate material 5 was covered with a low-pressure mercury lamp at a wavelength of 254 nm and an illuminance of 10 mW / cm.²Was irradiated with ultraviolet rays for 20 seconds. After that, when the contact angle of water 6 was immediately measured with a contact angle meter for the part where the halftone dots were written, the contact angle was 8 °, showing sufficient hydrophilicity.

Next, the 1,2-epoxy dodecane solution was roll-coated on the surface of the plate material 5, dried at 60 ° C. for 10 minutes, and then the contact angle of water 6 was measured with a contact angle meter. Was 84 °, showing sufficient hydrophobicity. As a result, it was confirmed that the plate material 5 returned to the "initial state at the time of plate production" and the plate could be regenerated.

&lt;Comparative Example&gt; The following three comparative example samples were prepared. (Sample 1) Instead of the intermediate layer 2 of the above example, an ammonium paratungstate solution was dip-coated on a plate material substrate, air-dried, and then fired at 500 ° C. for 1 hour to form the intermediate layer 2, except that the intermediate layer 2 was formed. Plate material 5 was produced in the same manner as in Examples. The thickness of the intermediate layer 2 made of tungsten oxide was about 0.1 μm.

(Sample 2) Instead of the intermediate layer 2 of the above-mentioned example, a transparent conductive material Cerames S-8 (manufactured by Taki Chemical Co., Ltd., an 8 wt% aqueous solution of tin oxide ultrafine particles) was dip-coated on the plate material substrate. After air-drying, the plate material 5 was prepared in the same manner as in Examples except that the intermediate layer 2 was formed by firing at 500 ° C. for 1 hour. The thickness of the intermediate layer 2 made of tin oxide was about 0.09 μm.

(Sample 3) The plate material 5 was produced in the same manner as in the examples except that the intermediate layer 2 of the above example was not formed and the photosensitive layer 3 was formed directly on the SUS substrate.

[Evaluation&gt; Next, the photocatalytic activity of the plate material 5 having the intermediate layer 2 composed of tungsten oxide and tin oxide and each of the above samples prepared in the examples, that is, the organic compound. At the same time as the decomposition of water 6, the photocatalytic activity of the photosensitive layer 3 to become hydrophilic to a contact angle of 10 ° or less was evaluated.

[0082] As a measurement procedure, each sample is roll-coated with a 1,2-epoxydodecan solution on the surface of the plate 5 in the same manner as in the examples, and dried at 60 ° C. for 10 minutes to expose the surface of the plate 5. After hydrophobizing the contact angle of water 6 to 81 ° to 85 °, it is irradiated with light having a wavelength of 405 nm, and the irradiation energy of the light until the surface of the plate 5 becomes a contact angle of 10 ° or less is measured. It should be noted that this irradiation energy is the energy required to write the hydrophilic non-image area.

As shown in FIG. 8, the plate material 5 having the intermediate layer 2 composed of tungsten oxide and tin oxide emits light having a wavelength of 405 nm at about 90 mJ / cm.²When irradiated, the surface of the plate 5 became hydrophilic to a contact angle of 10 ° or less, and it was confirmed that the non-image area could be written. On the other hand, the irradiation energy of the plate material 5 (sample 1) having the intermediate layer 2 made of tungsten oxide and the irradiation energy of the plate material 5 (sample 2) having the intermediate layer 2 made of tin oxide are about 650 mJ / cm, respectively.²And about 850mJ / cm²Although the irradiation energy is smaller than that of the plate material 5 (sample 3) without the intermediate layer 2, the irradiation energy is required several times as much as that of the plate material 5 having the intermediate layer 2 composed of tungsten oxide and tin oxide. It turns out that there is.

That is, the plate material 5 having the intermediate layer 2 composed of tungsten oxide and tin oxide has several times higher photocatalytic activity than the plate material 5 having the intermediate layer 2 composed of only tungsten oxide or only tin oxide. It could be confirmed. Next, the relationship between the contact angle of water 6 and the irradiation energy was investigated by changing the composition ratio of tungsten oxide and tin oxide in the intermediate layer 2 composed of tungsten oxide and tin oxide.

As shown in FIG. 9, the irradiation energy required for the surface of the plate 5 to exhibit hydrophilicity with a contact angle of 10 ° or less is WO of tungsten oxide and tin oxide by weight.₃/ SnO₂Approximately 330mJ / cm when mixed at a ratio of = 0.3 / 0.7², Tungsten oxide and tin oxide by weight ratio WO₃/ SnO₂Approximately 90mJ / cm when mixed at a ratio of = 0.5 / 0.5²WO of tungsten oxide and tin oxide by weight₃/ SnO₂Approximately 150mJ / cm when mixed at a ratio of = 0.7 / 0.3²This is the smallest when the weight ratio of tungsten oxide to tin oxide is 0.5: 0.5 (1: 1), and it can be seen that other than this ratio, a larger irradiation energy is required.

[0086] That is, by setting the weight ratio of tungsten oxide and tin oxide contained in the intermediate layer 2 to 0.5: 0.5, the surface of the plate material 5 can be made hydrophilic with lower irradiation energy. In other words, when trying to hydrophilize the surface of the plate 5 with the same irradiation energy, it can be hydrophilized in the shortest time when the weight ratio of tungsten oxide and tin oxide is 0.5: 0.5, and plate preparation and plate preparation and It is possible to shorten the time required for reproduction.

[0087] As described in detail above, according to the planographic printing plate material 5 according to the embodiment of the present invention, not only the effect that the plate can be reused but also the effect that the cycle can be accelerated. Can also be obtained. That is, the catalytic activity of the photocatalyst of the photosensitive layer 3 can be enhanced by providing a layer containing two or more kinds of oxides, that is, a so-called intermediate layer 2, between the base material 1 and the photosensitive layer 3 containing the photocatalyst. In other words, it does not take much time to realize them, whether it is to make a plate or to regenerate the plate. Therefore, the entire printing process can be completed extremely quickly.

[0088] Further, since light having a wavelength of 600 nm or less including visible light can be used as active light, visible light can be used for image writing and history erasing, and the handling and writing operation of the plate material 5 can be performed. It's easy. Furthermore, since the plate can be recycled and reused, the amount of plate material 5 discarded after use can be significantly reduced. Further, since the polymer is not used as the image portion, a cleaning liquid for cleaning the image portion polymer at the time of plate regeneration is also unnecessary. Therefore, it is not only environmentally friendly, but also the cost related to the plate material 5 can be significantly reduced.

[0089] Further, in a state where the planographic printing plate material 5 is attached to the printing machine 10, the plate can be produced and regenerated, and the operability can be improved without the need for plate replacement work. Furthermore, since it is possible to directly write an image on the plate material 5 from digital data related to the image, the printing process has been digitized, and the time has been significantly reduced or the cost has been reduced accordingly. Can be planned.

[0090] As described in detail above, according to the lithographic printing plate material of the present invention according to claim 1.<u style="single">Since the photocatalyst is a titanium oxide photocatalyst or a processed titanium oxide photocatalyst, the organic compound adhering to the photosensitive layer containing the photocatalyst can be decomposed under active light irradiation, and the hydrophilicity of the photocatalyst itself can be enhanced.</u>The intermediate layer interposed between the base material and the photosensitive layer is<u style="single">Since it contains tungsten oxide and tin oxide, the photosensitive layer containing the titanium oxide photocatalyst simultaneously improves the action of decomposing organic compounds and the action of making it hydrophilic under active light irradiation.</u>The surface of the photosensitive layer can be made hydrophilic with lower active light irradiation energy.

[0091] Therefore, the plate preparation time can be shortened by increasing the image writing speed by the active light on the surface of the plate material, and the plate reproduction time can be shortened by increasing the image history erasing speed by the active light. As a result, the print preparation time can be further shortened. Further, by regenerating the plate material and repeatedly using it, the amount of the plate material discarded after use can be remarkably reduced, and the cost related to the plate material can be reduced.

[0093] Claim<u style="single">2</u>According to the lithographic printing plate material of the present invention described, the mixing ratio of tungsten oxide and tin oxide is set to WO, respectively.₃And SnO₂Therefore, by setting the weight ratio to 1: 1, the active light irradiation energy required for hydrophilization of the surface of the photosensitive layer can be significantly reduced. Claim<u style="single">3</u>According to the plate material for flat plate printing of the present invention described, since the active light is light having a wavelength of 600 nm or less including visible light, it is possible to write an image with light having a wavelength of visible light to ultraviolet light, and the image can be written. It is possible to expand the choice of irradiation light of time.

[0094] Claim<u style="single">4</u>According to the lithographic printing plate material of the present invention described, the characteristics of the surface of the photosensitive layer are converted between hydrophilicity and hydrophobicity when the image is written on the plate material and when the plate is regenerated. An image can be formed depending on the state, and the plate can be reproduced by setting one of the two states. Claim<u style="single">5</u>According to the lithographic printing plate material of the present invention described, the characteristics of the surface of the photosensitive layer are changed from hydrophobic to hydrophilic when irradiated with active light, so that the surface of the hydrophobic photosensitive layer is irradiated with active light. By making the irradiated surface hydrophilic, an image consisting of a hydrophobic image portion and a hydrophilic non-image portion can be formed on the surface of the plate material. Further, by irradiating the entire surface of the plate material with active light, the entire surface of the plate material can be made hydrophilic, the image history can be erased, and the plate can be reproduced.

[0095] Claim<u style="single">6</u>According to the lithographic printing plate material of the present invention described, when the plate is regenerated, a hydrophobic organic compound having a property of being decomposed by the action of a photocatalyst when irradiated with active light is supplied to the surface of the photosensitive layer. The surface of the photosensitive layer is made hydrophobic by either irradiating the surface of the photosensitive layer with an energy bundle of light or electricity, or by applying friction to the surface of the photosensitive layer. By irradiating the layer surface with active light, only the irradiated surface can be made hydrophilic, and an image composed of a hydrophobic image portion and a hydrophilic non-image portion can be surely formed.

[0096] Claim<u style="single">7</u>According to the method for producing a lithographic printing plate material of the present invention described above, on the surface of the base material.<u style="single">With tungsten oxide and tin oxide</u>Since it is provided with an intermediate layer forming step of forming an intermediate layer including and improving charge separation efficiency and a photosensitive layer forming step of forming a photosensitive layer containing a photocatalyst that reacts with active light on the surface of the intermediate layer.<u style="single">Under active light irradiation, the photosensitive layer containing a photocatalyst can simultaneously improve the action of decomposing organic compounds and the action of hydrophilizing.</u>It is possible to produce a lithographic printing plate material capable of increasing the photocatalytic activity of the photosensitive layer and making the surface of the photosensitive layer hydrophilic with lower active light irradiation energy.

[0097] Therefore, the plate preparation time can be shortened by increasing the image writing speed by the active light on the surface of the plate material, and the plate reproduction time can be shortened by increasing the image history erasing speed by the active light. As a result, the print preparation time can be further shortened. Further, by regenerating the plate material and repeatedly using it, the amount of the plate material discarded after use can be remarkably reduced, and the cost related to the plate material can be reduced.

[0098] Claim<u style="single">8</u>According to the method for producing a lithographic printing plate material of the present invention described, the intermediate layer forming step is performed.<u style="single">Tungsten oxide and tin oxide on the surface of the base material</u>The sol solution containing the photocatalyst sol is applied and then the sol solution containing the oxide semiconductor is cured. The photosensitive layer forming step is the step of applying the sol solution containing the photocatalyst sol and then curing the sol solution containing the photocatalyst sol. Therefore, a plate material for flat plate printing can be produced by a sol coating method.

[0099] Claim<u style="single">9</u>According to the method for producing a lithographic printing plate material of the present invention described, the intermediate layer forming step is performed.<u style="single">Tungsten oxide and tin oxide</u>By sputtering using the target of<u style="single">With the above tungsten oxide and tin oxide</u>The photosensitive layer forming step is a step of forming a layer containing a photocatalyst by sputtering using a target containing a photocatalyst and then firing. It can be produced by a sputtering method.

[0100] According to the method for producing a plate material for flat plate printing according to claim 12, since two or more types of oxide semiconductors contain tungsten oxide and tin oxide, a photocatalyst is used under active light irradiation. It is possible to simultaneously improve the action of the containing photosensitive layer to decompose the organic compound and the action of making it hydrophilic.

[0101] Claim 1<u style="single">0</u>According to the printing press of the present invention described.<u style="single">6</u>An image writing that writes an image by irradiating the plate cylinder to which the above-mentioned plate printing plate material is attached, a plate surface hydrophobizing device that makes the plate material surface hydrophobic, and active light of 600 nm or less on the hydrophobized plate material surface. An apparatus, an inking roller that applies ink to the surface of the plate on which the image was written, a plate cleaning device that removes the ink applied to the surface of the plate, and active light on the surface of the plate after removing the ink. Since it is equipped with an image history erasing device that hydrophilizes the surface of the plate material by irradiating it and erases the image history of the plate material surface, the plate can be produced and regenerated with the plate material for flat plate printing attached to the printing machine. It is possible to improve operability without the need for plate replacement work.

[0102] Further, since the active light is light having a wavelength of 600 nm or less including visible light, it is possible to write an image with light having a wavelength of visible light to ultraviolet light, and it is possible to expand the options of irradiation light at the time of writing an image. Can be done. Further, by regenerating and repeatedly using the plate material, the amount of the plate material discarded after use can be remarkably reduced, and the cost related to the plate material can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] Fig. 1 is a schematic cross-sectional view of a plate material for lithographic printing according to an embodiment of the present invention in a case where the surface of the plate material exhibits hydrophobicity.

FIG. 2 is a schematic cross-sectional view of a plate material for lithographic printing according to an embodiment of the present invention in a case where the surface of the plate material exhibits hydrophilicity.

FIG. 3 is a flowchart for explaining the production and reproduction of a lithographic printing plate according to an embodiment of the present invention.

FIG. 4 is a diagram showing a cycle from image writing to reproduction of a lithographic printing plate according to an embodiment of the present invention.

FIG. 5 is a schematic perspective view showing an example of a lithographic printing plate according to an embodiment of the present invention.

FIG. 6 is a graph showing the relationship between the time (or operation) required for one embodiment of the present invention and the contact angle of water on the surface of a plate material.

FIG. 7 is a schematic view showing a printing machine that performs printing and plate reproduction according to an embodiment of the present invention.

FIG. 8 is a graph showing the relationship between the irradiation energy required for one embodiment of the present invention and the contact angle of water in a lithographic printing plate material.

FIG. 9 is a graph showing the relationship between the irradiation energy required for one embodiment of the present invention and the contact angle of water in a lithographic printing plate material.

[Description of code] 1 Base material 2 Intermediate layer containing two or more types of oxide semiconductors 3 Photosensitive layer containing photocatalyst 3a Non-image area 3b Image area 5 Plate material for lithographic printing 6 Water 10 Printing machine 11 Plate cylinder 12 Plate cleaning device 13 Image writing device 14 Plate surface hydrophobizing device 15 Heating device 16 Active light irradiation device for hydrophilization treatment (image history erasing device) 17 Inking roller 18 Damping water supply device 19 Blanket cylinder 20 Paper