JP2004066548A - Layered structure, its manufacturing method, lithographic printing plate material, its manufacturing method, and printing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a layer structure having a photocatalyst layer including a photocatalyst having an improved capacity of decomposing an organic compound under a heating atmosphere and a hydrophilizing capacity of the photocatalyst. <P>SOLUTION: This layered structure 5 has the photocatalyst layer 3 including the photocatalyst and simultaneously demonstrates both the decomposing performance of the organic compound existing on the surface of the photocatalyst layer 3 and the hydrophilizing performance of the surface of the photocatalyst layer 3 through the irradiation of an active ray having an energy larger than the band gap energy of the photocatalyst. By providing a water-holding layer 2 containing a water holding function between a substrate 1 and the layer 3, the photocatalysis performance under heating atmosphere is enhanced. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a layered component containing a photocatalyst and a method for producing the same, a recyclable lithographic printing plate having the layered component, a method for producing the same, and a printing machine.
[0002]
[Prior art]
As a general printing technique, digitization of a printing process is in progress. In this method, an image and a document are produced by a personal computer, or an image is read by a scanner or the like to digitize the image data, and a printing plate is produced directly from the digital data. This can save labor in the entire printing process and facilitate high-definition printing.
[0003]
The present inventors have proposed, in Japanese Patent Application Laid-Open No. 2000-62334, a printing plate material that can be reused while coping with the digitization of the printing process as described above, and a method of reproducing the printing plate material.
That is, using a coating material containing a titanium oxide photocatalyst formed on a substrate as a printing plate material, in the initial state at the time of plate production, the surface of the coating layer is adjusted to show a hydrophobic state, The surface is irradiated with light (ultraviolet light) having a wavelength higher than the band gap energy of the titanium oxide photocatalyst based on the above digital data, and a part of the surface is converted to a hydrophilic surface to make it hydrophobic. A plate composed of a non-image area and a hydrophilic image area is prepared. After the printing is completed, the irradiation of the energy flux or the chemical conversion treatment is performed in combination or alone to convert the entire surface of the coat layer to the initial state at the time of producing the hydrophobic plate again.
[0004]
Further, the present inventors disclosed in Japanese Patent Application Laid-Open No. 2000-62335, by applying a compound such as octadecyltrimethosisilane to the surface of the plate material, adjusting the surface to a state showing hydrophobicity, and performing printing. After the completion, a technique has been proposed in which the compound is applied again to convert the surface of the coating layer to an initial state at the time of producing a plate showing hydrophobicity.
[0005]
Further, a technique has been proposed in which a photocatalyst is made to coexist with silica or silicon to exhibit a high degree of hydrophilicity or to maintain the hydrophilicity for a long time.
For example, Japanese Patent No. 2756474 discloses a composite material in which a photocatalyst coating film containing silica and a photocatalyst such as titanium oxide is bonded to the surface of a base material, and further, particles of the photocatalyst material are uniformly dispersed on the surface of the base material. A composite material having a bonded photocatalytic coating made of silicon is disclosed. When the composite material is hydrophilized by photoexcitation, the surface of the composite material has a characteristic of maintaining good hydrophilicity for a long period of time under weak indoor lighting or in a dark place.
[0006]
Further, Japanese Patent No. 3077199 discloses a composition comprising photocatalyst particles such as titanium oxide, silica fine particles, and a precursor of silica or silicon on the surface of a base material, and hydrophilized by photoexcitation. This composition has features that make it possible to make the surface highly hydrophilic and maintain it.
Furthermore, Japanese Patent No. 3087682 discloses that a layer containing a photocatalytic oxide such as titanium oxide or a layer containing a photocatalytic oxide layer and silica on the surface of a base material via an acrylic silicon resin layer, Alternatively, a photocatalytic hydrophilic member formed with a layer containing a photocatalytic oxide and silicon is disclosed. This hydrophilic member exhibits a high degree of hydrophilicity in response to light excitation, and has a feature that the surface layer is firmly fixed to the substrate.
[0007]
By the way, regarding the relationship between photocatalytic performance and ambient temperature, for example, Japanese Patent Application Laid-Open No. 2002-79774 discloses sensitivity and sensitivity utilizing the specific temperature dependency of the polarity conversion speed and change degree of the “substance having photocatalytic capability”. A printing method with improved discrimination, a master and an apparatus embodying the same are disclosed. Specifically, after uniformly providing a layer of a hydrophobic substance on a printing master having photocatalytic ability, the surface of the master is heated to a temperature of 40 to 200 ° C. and irradiated with active light to form a hydrophilic region. And an image-like distribution of hydrophobic regions. That is, FIG. 1 of the above publication shows that the energy intensity is 1.3 mW / cm. ² As a result of measuring the time required for the surface to have a contact angle of 5 ° with water when the surface of titanium dioxide was irradiated with ultraviolet light (active light), the hydrophilicity required about 280 seconds at room temperature (room temperature) It is disclosed that at 60 ° C. it is reduced to about 100 seconds, and at 120 ° C. it is reduced to about 20 seconds. As described above, the publication discloses that the rate of hydrophilization can be increased by using the temperature effect. In this publication, TiO is used as a substance having photocatalytic ability. ₂ , RTiO ₃ , AB _2-x C _x D _3-x E _x O ₁₀ , SnO ₂ , ZrO ₂ , Bi ₂ O ₃ , ZnO and FeO _X And that a heat insulating layer is provided between the layer having photocatalytic ability and the support. As this heat insulating layer, a binding material selected from an organic polymer material and an inorganic sol-gel converting material is disclosed.
[0008]
[Problems to be solved by the invention]
The present inventors conducted research on image writing and image history erasing on a lithographic printing plate material having a layered composition containing a photocatalyst, and found that active light having illuminance sufficient to obtain a practical level of image writing speed was obtained. It was confirmed that when the image was written, the plate surface temperature increased. In such a state where the temperature of the printing plate is raised, in the configuration of the printing original plate disclosed in JP-A-2002-79774, the hydrophilicity of the photocatalyst is not necessarily enhanced by the activation light irradiation under heating. Rather, it was confirmed that the photocatalyst's hydrophilizing function could be reduced.
[0009]
Therefore, the present inventors have conducted intensive research to find out an essential factor for reliably improving both photocatalytic performance, that is, the performance of decomposing organic compounds and the performance of hydrolyzing the photocatalyst itself, at elevated temperatures. Was repeated.
That is, the present invention has a photocatalyst layer containing a photocatalyst, and irradiates the photocatalyst layer surface with active light having an energy larger than the bandgap energy of the photocatalyst under a heating atmosphere, so that the photocatalyst layer surface is promptly irradiated. An object of the present invention is to provide a layered component and a method for producing the same, which can be made hydrophilic.
[0010]
Also, having the layered composition, using the active light under a heating atmosphere, quickly write an image on the plate material surface with a small light irradiation energy, so that the plate can be manufactured without wet development processing, It is an object of the present invention to provide a lithographic printing plate material and a method for manufacturing the same, in which after the printing is completed, the history of the plate can be quickly erased with a small light irradiation energy so that the plate can be reproduced.
[0011]
Still another object of the present invention is to provide a printing press capable of producing and reproducing a plate while the lithographic printing plate material is mounted.
[0012]
[Means for Solving the Problems]
The present invention has taken the following means in order to solve the above-mentioned problems.
That is, the layered composition of the present invention has a photocatalyst layer containing a photocatalyst, and has light having an energy larger than the bandgap energy of the photocatalyst (hereinafter, having an effective energy that causes the photocatalyst of the present invention to exhibit catalytic activity). By irradiating the photocatalytic layer with organic compound present on the surface of the photocatalytic layer, and at the same time, the photocatalytic layer surface is rendered hydrophilic. In addition, a water storage layer containing a substance having a water storage function is provided between the substrate and the photocatalyst layer.
[0013]
With this configuration, the ability to decompose the organic compound and the ability to hydrophilize the surface of the layer containing the photocatalyst are significantly improved in a heated atmosphere.
Further, the substance having the water storage function is preferably a silica-based compound.
Further, the photocatalyst is preferably a titanium oxide photocatalyst or a visible light responsive titanium oxide photocatalyst.
[0014]
Here, the visible light responsive titanium oxide photocatalyst is a titanium oxide photocatalyst based on a titanium oxide photocatalyst doped or supported with a metal element or a nonmetal element other than the element originally contained in the titanium oxide photocatalyst, or a titanium oxide photocatalyst. In which the ratio of the Ti element to the O element is shifted from the stoichiometric ratio, that is, the ratio of 1 oxygen atom to 1 oxygen atom.
[0015]
When the titanium oxide photocatalyst has, for example, an anatase crystal, the bandgap energy is 3.2 eV, and light having a wavelength of 380 nm or less is active light. By forming an impurity level in the band gap, the band gap energy can be reduced, and light having a wavelength of 600 nm or less can be used as active light.
[0016]
The method for producing a layered component of the present invention is a method for producing the above layered component, wherein the water storage layer is formed on the substrate, and then the photocatalytic layer is formed on the water storage layer. It is characterized by:
The lithographic printing plate material of the present invention has the above-mentioned layered component, and when the surface of the photocatalyst layer is irradiated with the active light in a heating atmosphere, image writing and image history erasing are rapidly performed, and reproduction is performed. It is characterized by being used.
[0017]
When an image is written on a lithographic printing plate material using a photocatalyst by activating light, in order to finish the writing operation within a practical writing time, the illuminance of light used for image writing is increased to increase the hydrophobicity / hydrophilicity. The conversion needs to be done in a short time.
When light of such an illuminance that allows practical writing is applied, an increase in the temperature of the plate surface is observed. Therefore, the term `` under heating atmosphere '' or `` heated state '' in the present invention means not only a case where the plate surface is heated again by using a device for heating the plate surface, but also, as in the writing step, It goes without saying that a situation where the temperature of the plate surface is increased only by performing necessary operations in each step of plate production and plate reproduction is included.
[0018]
Further, at the time of writing the image and erasing the image history, it is preferable that the characteristics of the surface of the photocatalyst layer be changed from hydrophobic to hydrophilic.
That is, by irradiating the surface of the lithographic printing plate with active light, it is possible to convert the irradiated surface from hydrophobic to hydrophilic. This is due to both the action of hydrophilizing the photocatalyst or the action of hydrophilizing the photocatalyst, and the action of decomposing the organic compound by the photocatalyst.
[0019]
Then, the printing plate surface converted to hydrophilic functions as a non-image area where the dampening solution adheres preferentially and the 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, and functions as an image portion to which the dampening solution does not adhere.
Further, in the reproduction of the printing plate after printing, the ink and paper powder attached to the printing plate surface are washed and removed, and then the entire printing surface is irradiated with actinic light to make the entire printing surface uniformly hydrophilic. History (image history) is deleted.
[0020]
Preferably, the active light is light having a wavelength of 600 nm or less. More preferably, light having a wavelength of 500 nm or less is used. By irradiating such actinic light, the surface of the photocatalytic layer, that is, the surface (plate surface) of the lithographic printing plate material is converted from hydrophobic to hydrophilic as described above.
The photocatalytic layer surface is irradiated with light or electric energy flux alone or in combination, and the photocatalytic layer surface is subjected to friction, and an organic system interacting with the photocatalytic layer surface. It is preferable that the surface of the photocatalyst layer is hydrophobized by either of the following: supplying a compound to the surface of the photocatalyst layer (claim 8). In this way, it is possible to reproduce the plate by converting the entire surface of the plate surface that has been hydrophilized to hydrophobic after printing.
[0021]
The method for producing a lithographic printing plate material according to the present invention is a method for producing the lithographic printing plate material described above, wherein after forming the water storage layer on the substrate, the photocatalyst is formed on the water storage layer. It is characterized by forming a layer.
The printing press of the present invention includes a plate cylinder on which the lithographic printing plate material is mounted, a hydrophobizing device for hydrophobizing the photocatalyst layer surface, and an active light of 600 nm or less applied to the hydrophobized photocatalyst layer surface. An image writing device for writing an image by irradiation, a plate cleaning device for removing ink applied to the surface of the photocatalyst layer after printing, and irradiating the surface of the photocatalyst layer with the active light after removing the ink. And a heating device for heating the surface of the photocatalyst layer when irradiating with the active light, and an image history erasing device for erasing the surface of the photocatalyst layer by hydrophilizing the surface of the photocatalyst layer.
[0022]
Further, it is preferable that the heating device heats the photocatalytic layer surface by light irradiation. Alternatively, the heating device preferably heats the photocatalytic layer surface by electric heating.
[0023]
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 layered structure according to a first embodiment of the present invention. FIG. 1 is a schematic cross-sectional view when the surface of the layered structure shows hydrophobicity. FIG. 3 is a schematic cross-sectional view in the case where the surface of the layered structure shows hydrophilicity.
[0024]
As shown in FIG. 1, a layered structure 5 includes a base material (or support) 1, a water storage layer (hereinafter simply referred to as a water storage layer) 2 containing a substance having a water storage function, and a photocatalyst including a photocatalyst. And a layer (hereinafter simply referred to as a photocatalyst layer) 3.
The substrate 1 is made of a metal such as aluminum or stainless steel, a polymer film, or the like. However, the substrate 1 is not limited to a metal such as aluminum or stainless steel, or a polymer film, and is not limited to the properties required when the photocatalyst layer 3 is put to practical use. May be selected according to the properties such as flexibility, surface hardness, thermal conductivity, electrical conductivity, and durability.
[0025]
The water storage layer 2 is formed on the surface of the substrate 1. In FIGS. 1 and 2, the water storage layer 2 is formed so as to be in contact with the photocatalyst layer 3. However, the water storage layer 2 is not necessarily in contact with the photocatalyst layer 3 and may be provided between the base material 1 and the photocatalyst layer 3. Good.
As the substance having a water storage function contained in the water storage layer 2, a silica-based compound is particularly preferable. Specifically, a silica film precursor capable of forming a silica film such as a silica film, an organosilicon compound, and water glass, or a silica fine particle or a silica fine particle precursor capable of forming silica fine particles is preferable. When the substance having a water storage function is fine particles, it is preferable to form a film using a hydrophilic binder.
[0026]
Further, in order to ensure that the base material 1 and the water storage layer 2 adhere to each other or to improve the adhesion between the base material 1 and the water storage layer 2, the base material 1 and the water storage layer 2 An undercoat layer (not shown) may be provided between them. When an undercoat layer is provided, for example, silica (SiO ₂ ), Silicon-based compounds such as silicone resin and silicone rubber are preferably used as the material. In particular, when a silicon resin is used, it is preferable to use silicon alkyd, silicon urethane, silicon epoxy, silicon acryl, silicon polyester, or the like.
[0027]
Further, when the water storage layer 2 is subjected to heat treatment for forming a photocatalyst layer 3 described later, it is possible to prevent impurities from thermally diffusing from the base material 1 and mixing into the photocatalyst layer 3 to lower the photocatalytic activity. There is also an effect. The water storage layer 2 also has an effect of protecting the base material 1 when the base material 1 is formed of a polymer film or the like.
Incidentally, even when the water storage layer 2 is provided on the photocatalyst layer 3 or when the photocatalyst layer 3 contains a substance having a water storage function, the photocatalytic activity at normal temperature Also, it was confirmed that the photocatalytic activity under the heating atmosphere was higher.
[0028]
However, when the water storage layer 2 is provided as a layer above the photocatalyst layer 3 or when a substance having a water storage function is contained inside the photocatalyst layer 3, the ratio of the photocatalyst exposed to the surface decreases. The photocatalytic activity is lower than when the water storage layer 2 is provided as an intermediate layer between the substrate 1 and the photocatalyst layer 3 as in the present embodiment.
Therefore, when the layered composition 5 having high photocatalytic activity at room temperature is first formed, and a substance having a water storage function coexists with the photocatalyst in order to further enhance the photocatalytic activity in a heating atmosphere, the present embodiment As described above, it is needless to say that the photocatalyst layer 3 is preferably the uppermost layer (outermost layer) and the water storage layer 2 is provided between the base material 1 and the photocatalyst layer 3.
[0029]
The reason why the photocatalytic activity under heating is improved by providing the water storage layer 2 between the base material 1 and the photocatalyst layer 3 is presumed as follows.
That is, when the photocatalyst is irradiated with active light, the photocatalyst generates electrons and holes, and the holes react with the adsorbed water molecules on the surface of the photocatalyst layer 3 to generate OH radicals (hydroxy radicals). This OH radical is said to oxidatively decompose organic compounds. Therefore, under a heated atmosphere, the amount of water adsorbed is usually reduced, and the molecular weight of water in the atmosphere is also reduced. As a result, the amount of water molecules required for OH radical generation becomes insufficient, resulting in a reduced amount of OH radical generated. However, the performance of the photocatalyst for decomposing organic substances is reduced. Therefore, by coexisting a substance having a water storage function near the photocatalyst, a sufficient amount of water molecules are supplied from the substance having a water storage function to the photocatalyst in a heated atmosphere, so that a large amount of OH radicals are generated, and an oxidative decomposition reaction is caused. It is presumed that since the substance itself is promoted by heating, the organic matter decomposition performance is improved as a result.
[0030]
By increasing the action of the photocatalyst in a heated atmosphere in this way, when the layered structure 5 having the photocatalyst layer 3 is used as a lithographic printing plate material, the active light irradiating portion is used when writing an image on the plate surface with active light. , Or by heating the plate surface with the energy of the active light itself, it is possible to reduce the irradiation energy of the active light required for conversion from hydrophobicity to hydrophilicity (hereinafter referred to as hydrophilization energy). . This makes it possible to shorten the plate making time by increasing the writing speed, or to reduce the output of the image writing device to reduce the cost of the writing device. Also, when erasing the image history of the printing plate, by simultaneously raising the temperature of the printing plate and activating the active light, it becomes possible to reduce the irradiation energy of the active light required for erasing the history. The output of the history erasing device can be reduced (that is, the manufacturing cost can be reduced).
[0031]
The photocatalyst layer 3 is formed on the water storage layer 2. The surface of the photocatalyst layer 3 is irradiated with active light having energy higher than the band gap energy of the photocatalyst to decompose the organic compound attached to the surface of the photocatalyst layer 3 and at the same time, the photocatalyst itself has a high hydrophilicity. To show sex.
One of the features of the present invention is that the photocatalyst layer 3 is formed using a photocatalyst in which the active light is light having a wavelength of 600 nm or less. That is, by irradiating the photocatalyst layer 3 with light having a wavelength of 600 nm or less, the surface of the photocatalyst layer 3 decomposes the organic compound and exhibits high hydrophilicity.
[0032]
Essentially, a photocatalyst does not exhibit photocatalytic activity unless irradiated with light having an energy higher than the band gap. For example, an anatase-type titanium oxide photocatalyst has a bandgap energy of 3.2 eV, and therefore responds only to ultraviolet light having a wavelength of 380 nm or less. In the present invention, a photocatalyst that responds to light having a wavelength of 600 nm or less by forming a new level between the band gaps is used. The light having a wavelength of 600 nm or less includes ultraviolet rays, but the photocatalyst of the present invention is characterized in that the same operation is performed regardless of whether or not ultraviolet rays are included in the active light. .
[0033]
In addition, as a method for producing such a photocatalyst that responds to light having a wavelength of 600 nm or less, a known method may be used. For example, JP-A-2001-207082 discloses a visible light responsive photocatalyst doped with a nitrogen atom, and JP-A-2001-205104 discloses a visible light responsive photocatalyst doped with a chromium atom and a nitrogen atom. Have been. Further, JP-A-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 visible light responsive photocatalyst carrying platinum have been published. In producing the plate material of the present invention, a visible light responsive photocatalyst (for example, a visible light responsive titanium oxide photocatalyst) produced by these known methods may be used.
[0034]
The titanium oxide photocatalyst includes rutile type, anatase type, and brookite type. In the present embodiment, any of them can be used, and a mixture of these may be used. Further, as the photocatalyst, a titanium oxide photocatalyst is suitable, but is not limited thereto.
In addition, the following substances may be added to the photocatalyst layer 3 for the purpose of maintaining hydrophilic properties or improving the strength of the photocatalyst layer 3 and the adhesion to the water storage layer 2. . Examples of this substance include silica-based compounds such as silica, silica sol, organosilane, and silicone resin; metal oxides and hydroxides such as zirconium, aluminum, and titanium; and fluorine-based resins. .
[0035]
Further, the thickness of the photocatalyst layer 2 is preferably in the range of 0.005 to 1 μm. This is because, 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 photocatalyst layer 2 is liable to cause cracks and the printing durability is reduced. This is because it becomes a factor. Note that this crack is remarkably observed when the film thickness exceeds 10 μm, so it is necessary to recognize 10 μm as the upper limit even if the above range is relaxed. In practice, it is more preferable to set the thickness to about 0.03 to 0.5 μm.
[0036]
The photocatalyst layer 2 may be formed by appropriately selecting a sol coating method, an organic titanate method, a sputtering method, a CVD method, a PVD method, or the like. Among these, the sol-gel method is particularly preferred in that the process is simple, and the sputtering method is preferred in that the film strength can be increased. Therefore, when the layered component 5 is used as a planographic printing plate material, if the photocatalytic layer 3 is formed by, for example, a sputtering method, high printing durability can be obtained.
[0037]
If the sol-gel method is adopted, in the sol used for this, in addition to the titanium oxide photocatalyst and the various substances for improving the strength of the photocatalyst layer 3 and the adhesion to the water storage layer 2, You may add a solvent, a crosslinking agent, a surfactant, etc. The sol may be a room temperature drying type or a heat drying type, but the latter is more preferable. This is because increasing the strength of the photocatalytic layer 3 by heating is advantageous for improving the printing durability of the plate.
[0038]
Further, on the photocatalyst layer 3 which responds to light having a wavelength of 600 nm or less, a photocatalyst layer (not shown) which responds to light having a wavelength of 380 nm or less is further provided as a protective layer, or for the purpose of easily maintaining hydrophilicity. A silica layer (not shown) may be provided. The photocatalyst layer 3 in the present invention may include the above-mentioned layers in some cases. Note that the photocatalyst layer 3 may be a layer composed of a single photocatalyst.
[0039]
As described above, in the present invention, basically, the layered structure 5 having the photocatalyst layer 3 can be used as a lithographic printing plate material. Further, for example, when aluminum is used as the base material 1, if necessary, the surface is roughened by anodizing or the like, so-called graining treatment is performed to further improve the function suitable for printing. Is also good. Therefore, the layered structure 5 having the photocatalyst layer 3 can be used as it is as a lithographic printing plate material, or the grained substrate 1 may be used.
[0040]
Further, since the layered structure of the present invention exhibits a catalytic activity significantly higher than room temperature under a heated atmosphere, the layered structure 5 is used particularly for a surface layer of a structure used under a heated atmosphere, for example, a chimney. If, for example, the photocatalyst decomposes organic compounds in the contaminant components, and the inorganic compounds that cannot be decomposed by the photocatalyst because they exhibit high hydrophilicity easily run off with rainwater, the outer wall surfaces of the compounds should be hardly contaminated. Is also possible.
[0041]
When the layered component 5 is used as a lithographic printing plate material, the organic compound for hydrophobizing the photocatalyst layer 3 is supplied to the plate material surface (plate surface) and dried or heated and dried as necessary. It is preferable that the surface of the photocatalyst layer 3 is made hydrophobic by reacting or strongly interacting with the plate surface, that is, the surface of the photocatalyst layer 3, and decomposed by the action of the photocatalyst to be removed from the surface of the photocatalyst layer 3. As such an organic compound, specifically, an organic titanium compound, an organic silane compound, an isocyanate compound, or an epoxide compound is preferable. Since these compounds react with hydroxyl groups existing on the surface of the hydrophilic photocatalyst layer 3 and are fixed on the surface, in principle, a monomolecular organic compound layer (not shown) is formed on the surface of the photocatalyst layer 3. Form. Since the surface of the photocatalyst layer 3 is hydrophobized with the monomolecular layer in this manner, the decomposition of the organic compound under irradiation with active light is facilitated.
[0042]
Examples of such an organic titanium compound include: 1) alkoxytitanium such as tetra-i-propoxytitanium, tetra-n-propoxytitanium, tetra-n-butoxytitanium, tetra-i-butoxytitanium, and tetrastearoxytitanium; 2) Titanium acylates such as tri-n-butoxytitanium stearate and isopropoxytitanium tristearate; 3) titanium chelates such as diisopropoxytitanium bisacetylacetonate, dihydroxybislactotitanium, titanium-i-propoxyoctylene glycol; And the like, but are not limited to these.
[0043]
Examples of the organic silane compound include: 1) trimethylmethoxysilane, trimethylethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, tetramethoxysilane, methyltriethoxysilane, tetraethoxysilane, methyldimethoxysilane, octadecyltrimethoxysilane, Alkoxysilanes such as octadecyltriethoxysilane, 2) chlorosilanes such as trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, methyldichlorosilane, dimethylchlorosilane, 3) vinyltrichlorosilane, vinyltriethoxysilane, γ-chloropropyltrimethoxysilane , Γ-chloropropylmethyldichlorosilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropylmethyldiethoxysilane Silane coupling agents such as γ- aminopropyltriethoxysilane, 4) fluoroalkyl silanes such as perfluoroalkyl silane, it is like, not limited thereto.
[0044]
Examples of the isocyanate compound include dodecyl isocyanate and octadecyl isocyanate, but are not limited thereto.
Further, examples of the epoxide-based compound include 1,2-epoxydecane, 1,2-epoxyhexadecane, and 1,2-epoxyoctadecane, but are not limited thereto.
[0045]
When the above-mentioned organic compound is a liquid at room temperature, it may be applied to the surface of the photocatalyst layer 3 by a method such as blade coating, roll coating, dip coating or the like, or may be applied as fine droplets by spraying or the like. Further, a method of heating and vaporizing at a temperature equal to or lower than the decomposition temperature or vaporizing using a liquid atomizer using ultrasonic waves, a so-called nebulizer or the like and spraying the photocatalyst layer 3 surface is used. May be. Further, it goes without saying that the organic compound may be used by dissolving it in another liquid for the purpose of adjusting the concentration and viscosity of the organic compound.
[0046]
Hereinafter, a method for producing a plate and a method for reproducing the plate when the layered composition 5 of the present invention is applied to a lithographic printing plate material will be described. Accordingly, hereinafter, the layered structure 5 will be described as a lithographic printing plate 5. The planographic printing plate material 5 is simply referred to as a plate material, and the plate material 5 having an image area for printing formed on its surface is referred to as a plate (lithographic printing plate).
[0047]
First, a method of manufacturing a plate will be described. FIG. 4 shows a conceptual diagram of production and reproduction of a plate. In the following, "preparation of the plate" means that after hydrophobizing the surface of the plate material 5, at least a part of the plate surface is irradiated with active light based on digital data to form a hydrophilic non-image area, This means that a latent image composed of a hydrophobic image portion and a hydrophilic non-image portion is formed on the plate surface together with the hydrophobic portion of the plate surface that has not been irradiated with active light.
[0048]
First, the plate surface (that is, the surface of the photocatalyst layer 3) is irradiated with the active light to make the entire surface of the plate a hydrophilic surface having a contact angle of water of 10 ° or less, so that the state shown in FIG. 2 appears. As a result, the history of the printing plate is erased (see FIG. 4E).
Next, the plate is irradiated with an energy flux such as light or electricity, mechanical stimulus such as friction is applied to the plate, or an organic compound interacting with the plate is supplied to the plate to make the photocatalytic property hydrophilic. Is converted to hydrophobic to make the entire surface hydrophobic. FIG. 4A shows a state where the entire surface of the plate has been hydrophobized. The term "hydrophobic printing plate" as used herein means a printing plate having a contact angle of water of 50 ° or more, preferably 80 ° or more, as shown in FIG. Adhesion of water has been difficult.
[0049]
This state of the plate surface is referred to as an "initial state at the time of plate production". The "initial state at the time of plate production" mentioned above may be regarded as the start of the actual printing process. More specifically, for an arbitrary image, it can be regarded as indicating a state where digitized data has already been prepared and this is to be written on a printing plate.
[0050]
Next, a non-image area is written on the plate surface in the hydrophobic state by using active light as an image writing step. This non-image portion is performed in accordance with digital data relating to an image so as to correspond to the data. Here, the non-image area is a hydrophilic area having a contact angle of water of 10 ° or less, where the dampening solution easily adheres, while the adhesion of the printing ink becomes difficult. I have.
[0051]
As a method of exposing a hydrophilic non-image area based on image data, a method of irradiating the plate surface with actinic light and hydrophilizing the plate surface by the action of a photocatalyst is used. Since the plate surface that has not been irradiated with the active light remains hydrophobic, a latent image composed of a hydrophobic image portion and a hydrophilic non-image portion is formed on the plate surface, and a plate is thereby produced. . Here, as shown in FIG. 4B, the non-image portion is written by a writing head using a violet laser having a wavelength of 405 nm, for example, a visible light, and the non-image portion is formed on the hydrophobic printing plate. I have.
[0052]
In addition, as a method for exposing a hydrophilic non-image area based on image data, besides a writing head using a violet laser having a wavelength of 405 nm, for example, a UV setter 710 published by Basis Print (Germany) is used. It goes without saying that any system that can write an image using active light, such as a writing head that uses a UV light source and a micromirror, can be used as a writing device.
[0053]
In addition, by raising the temperature of the printing plate at the time of writing the image, it becomes possible to write the image at a higher speed or to write the image with a smaller activation light irradiation energy. As a heating means for the plate surface, for example, as shown in FIG. When heating by light irradiation as described above, it is preferable to use infrared IR (including near infrared) in consideration of heating efficiency. Needless to say, electric heating may be used as a heating means for the plate surface. Further, when the plate surface is heated only by the irradiation of the actinic light used for image writing and the plate surface is heated to an appropriate temperature for promptly performing image writing, it is not necessary to use the heating means. Needless to say.
[0054]
In this way, as shown in FIG. 4C, the formation of the image portion and the non-image portion on the plate surface is completed, and a printable state is established.
Then, a so-called emulsified ink obtained by mixing a fountain solution with a fountain solution and a hydrophobic ink for printing and a fountain solution is applied to the plate surface. Thereby, for example, a plate as shown in FIG. 5 is produced.
[0055]
In FIG. 5, a shaded portion shows a state in which hydrophobic ink has adhered to the hydrophobic image portion 3b. The remaining white part, that is, the hydrophilic non-image area 3a, shows a state in which the dampening solution adheres preferentially, while the hydrophobic ink is repelled and does not adhere. When the picture (image) emerges as described above, the plate 5 has a function as a plate. Thereafter, a normal printing process is executed, and the process is terminated.
[0056]
Next, a method of reproducing a plate will be described. The term “reproduction of a plate” refers to a method in which at least a part of a plate surface shows hydrophobicity and the rest shows hydrophilicity, and the entire surface is uniformly hydrophilized. By irradiating the plate with a single or a combination of, or applying mechanical stimuli such as friction to the plate, or supplying an organic compound that interacts with the plate to the plate to convert the photocatalytic properties from hydrophilic to hydrophobic. To restore the “initial state at the time of plate production” again.
[0057]
First, as shown in FIG. 4D, as an ink removing step, ink, fountain solution, paper dust and the like adhering to the plate surface after printing are removed. This method includes stopping ink supply to the printing plate and reducing printing, wiping the ink on the printing plate with a mechanism that winds up a cloth tape for wiping the ink, and printing on the printing plate with a roller wrapped with a cloth for wiping the ink. The method of wiping the ink, and the method of spraying a cleaning liquid onto the plate surface with a spray to wash the ink may be used as appropriate.
[0058]
Thereafter, the entire surface of the plate surface at least partially showing hydrophobicity is irradiated with active light. By doing so, it is possible to make the image area hydrophilic and make the entire plate surface a hydrophilic surface with a contact angle of water of about 10 °, that is, the state shown in FIG.
By irradiating the actinic light, the characteristic that the hydrophobic image portion existing on the plate surface is converted into a surface having high hydrophilicity is achieved by using a titanium oxide photocatalyst or a visible light responsive titanium oxide photocatalyst. be able to. In this case, as shown in FIG. 4 (e), an ultraviolet irradiation lamp (UV lamp) is used to convert the hydrophobic image portion to hydrophilic by irradiating ultraviolet light, to make the entire surface of the plate hydrophilic, and The case where the history of is deleted is shown. At this time, at the same time as the activation light irradiation, for example, as shown in FIG. 4E, the plate surface is irradiated with infrared light using an IR lamp, or the plate surface is heated using an electric heating device. The history can be erased with less activation light irradiation energy.
[0059]
Next, as shown in FIG. 4 (a), the plate surface, which has been completely restored to hydrophilicity by the irradiation of ultraviolet rays, is irradiated with a single or a plurality of energy fluxes such as light and electricity, or a mechanical stimulus such as friction. Is added to the plate surface, or an organic compound that interacts with the plate surface is supplied to the plate surface, whereby the photocatalytic property can be changed from hydrophilic to hydrophobic and returned to the initial state at the time of plate production.
[0060]
FIG. 6 is a graph summarizing the above description. 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 plate material surface (see FIGS. 1 and 2). It shows how the contact angle (that is, hydrophobic or hydrophilic state) of the plate changes with time or operation. In FIG. 6, a dashed line indicates a non-image portion of the plate surface, and a solid line indicates an image portion.
[0061]
First, the plate surface is irradiated with actinic light so that the contact angle of the water 6 shows a high hydrophilicity of 10 ° or less (time point a).
In the hydrophobizing step (step A), the plate is irradiated with an energy flux such as light or electricity alone or in combination, or a mechanical stimulus such as friction is applied to the plate, or the organic layer interacts with the plate. The photocatalytic property is converted from hydrophilic to hydrophobic by supplying the system compound to the plate surface. The state in which the regeneration by the hydrophobization is completed is the "initial state at the time of plate production". In this state, the contact angle of water 6 on the plate surface is 50 ° or more, preferably 80 ° or more.
[0062]
Next, as a non-image area writing step (step B), writing of the non-image area on the hydrophobic printing plate is started with active light (time point b). By doing so, the portion of the plate surface irradiated with the active light is converted from hydrophobic to hydrophilic by the action of the photocatalyst, and becomes a hydrophilic non-image area. That is, the contact angle of the water 6 on the plate surface is 10 ° or less. On the other hand, the plate surface that has not been irradiated with the actinic light maintains a hydrophobic state, so that the portion of the plate surface that has not been irradiated with the actinic light becomes a hydrophobic image portion, and the plate member 5 can function as a plate.
[0063]
After the writing of the non-image area is completed, printing is started as a printing step (step C) (time point c).
When printing is completed, ink, stains, and the like on the plate surface are removed as an ink removing step (step D) (time point d).
Then, after the ink removal is completed, irradiation of the plate surface with active light is started as a step of hydrophilizing the image area (step E) (time point e). By doing so, the hydrophobic image portion is converted into a hydrophilic non-image portion by the action of the photocatalyst, and the entire surface of the printing plate returns to hydrophilic again.
[0064]
Thereafter, as a next hydrophobic treatment step (step A '), the plate is irradiated with an energy flux such as light or electricity, alone or in combination, or a mechanical stimulus such as friction is applied to the plate or By supplying the interacting organic compound to the printing plate, the printing plate returns to the “initial state at the time of plate preparation”, and the printing plate 5 is reused (time point a ′).
[0065]
In the following, more specific examples and comparative examples confirmed by the inventors of the present invention relating to the production of the plate material 5 and the production and reproduction of the plate will be described.
[A] Example
(1) Preparation of photocatalyst
Aqueous ammonia was added to the raw material titanium sulfate (Wako Pure Chemical) while stirring to obtain a hydrolyzate of titanium sulfate. This hydrolyzate was filtered using a Nutsche, and washed with ion-exchanged water until the electric conductivity of the filtrate became 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 calcined product was first ground in a mortar to obtain a photocatalyst powder.
[0066]
(2) Confirmation of visible light activity
0.2 g of the photocatalyst powder was collected and uniformly spread on the bottom of a cylindrical container (capacity: 500 mL) made of Pyrex (registered trademark) glass that can be hermetically sealed. Next, the inside of the reaction vessel was evacuated and then replaced with high-purity air. Thereafter, acetone was injected so that the concentration in the reaction vessel became 500 ppm, and the mixture was adsorbed at 25 ° C. in a dark place for 10 hours until the adsorption became parallel. Then, a blue LED (main wavelength: 470 nm) manufactured by Nichia Chemical Co., Ltd. is irradiated, and acetone and CO 2 are emitted. ₂ As a result of tracking the amount by a gas chromatograph made by Shimadzu, acetone disappeared after 20 hours of irradiation with the blue LED, and instead, CO2 corresponding to the stoichiometric ratio of acetone was used. ₂ Occurrence was confirmed. That is, it was confirmed that the photocatalyst powder exhibited catalytic activity with light having a wavelength of 470 nm.
[0067]
(3) Manufacture of lithographic printing plates
(3-1) Preparation of Photocatalyst Dispersion and Substrate 1
The photocatalyst powder was dispersed in ion-exchanged water to obtain a slurry having a solid content of 20% by weight (wt%). After adding 1% by weight of a polycarboxylic acid-based dispersing agent to the photocatalyst to this slurry, it was pulverized with a wet mill (trade name: Dino Mill PILOT) to obtain a photocatalyst dispersion liquid.
Further, a stainless steel (SUS301) base material 1 having a size of 280 × 204 mm and a thickness of 0.1 mm was prepared and subjected to an alkali degreasing treatment to obtain a plate material substrate 1.
[0068]
(3-2) Formation of water storage layer 2
Li ₂ O-containing water glass LSS-35 (manufactured by Nissan Chemical Industries) ₂ Diluted to 5 wt% solids, SiO ₂ A coating solution was prepared. This SiO ₂ The coating liquid was dip-coated on the substrate 1, air-dried, baked at 500 ° C. for 1 hour, ₂ The water storage layer 2 was formed. SiO ₂ The thickness of the water storage layer 2 was about 0.12 μm.
[0069]
(3-3) Formation of photocatalyst layer 3
The photocatalyst dispersion liquid and a titanium oxide coating agent TKC-301 manufactured by Teika Co., Ltd. ₂ The solution mixed at a weight ratio of 6: 4 as the SiO 2 ₂ The substrate 1 coated with the water storage layer 2 was dip-coated, air-dried, and baked at 350 ° C. for 1 hour to form a photocatalyst layer 3, which was a planographic printing plate material 5. The thickness of the photocatalyst layer 3 was about 0.1 μm. When the contact angle of water 6 on the plate surface was measured with a CA-W contact angle meter manufactured by Kyowa Interface Science, the contact angle was 8 °, indicating sufficient hydrophilicity.
[0070]
(4) Hydrophobicization of plate surface
Next, 1,2-epoxide dodecane (Wako Pure Chemical Industries, Ltd.) was dissolved in isoparaffin (trade name: Isopar L, manufactured by ExxonMobil) to obtain a 1 wt% solution. Then, the 1,2-epoxide decane solution was roll-coated on the surface of the plate material and dried at 60 ° C. for 10 minutes. Then, when the contact angle of the water 6 was measured by the contact angle meter, the contact angle was 83 °, showing sufficient hydrophobicity, indicating that the surface of the plate 5 was in an initial state at the time of plate preparation. confirmed.
[0071]
(5) Measurement of hydrophilization energy change due to plate surface temperature change
By changing the surface temperature of the hydrophobized plate material 5, the wavelength is 360 nm and the illuminance is 10 mW / cm. ² And irradiating the plate surface temperature as described above to obtain a hydrophilizing energy from the product of the active light irradiation time and the active light illuminance until the contact angle becomes 10 ° or less from the state in which the plate surface has been hydrophobized. The change in hydrophilization energy accompanying the change was measured. FIG. 3 shows the measurement results.
[0072]
As shown by the solid line in FIG. ₂ Photocatalyst layer 3 / SiO ₂ The water storage layer 2 / stainless steel substrate 1) has a hydrophilization energy of 0.1 J / cm at a plate surface temperature of 25 ° C. ² Is 0.04 J / cm at a plate surface temperature of 100 ° C. ² 0.02 J / cm at a plate surface temperature of 200 ° C. ² Met. Thus, it can be seen that the higher the plate surface temperature, the smaller the hydrophilizing energy (active light irradiation energy required for hydrophilizing).
[0073]
(6) Image writing
Next, using the UV setter 710 published by Basis Print (Germany), which can write an image (non-image area) by exposing to ultraviolet light having a wavelength of 360 to 450 nm, the plate surface subjected to the hydrophobic treatment. A halftone dot image was written in 10% increments from 10% to 100%. At the time of writing, the plate surface is irradiated with infrared rays 0.1 seconds before writing the image with the active light to instantaneously raise the temperature of the plate surface to about 240 ° C., and the plate surface temperature at the time of writing with the active light is 200 ° C. The image was written under the condition that the temperature slightly exceeded the temperature. The illuminance of the UV setter 710 on the plate surface having a wavelength of 360 nm is 200 mW / cm. ² Therefore, the active light irradiation time for one area is 0.1 second, and the irradiation energy is 0.02 J / cm. ² Set to.
[0074]
Since the size of one area is 17 mm × 13 mm, it took 24 seconds to write an image on a plate having a size of 280 × 204 mm (image area is 272 mm × 195 mm). When the contact angle of water 6 on the plate surface after the writing was completed was measured by the contact angle meter, the contact angle of the written portion was 8 °, which became a hydrophilic non-image portion, and the contact angle of the unwritten portion was 83 °. It was confirmed that the image area had hydrophobicity.
[0075]
(7) Printing
This plate material was installed on a New Ace Pro desktop offset printing machine of Alpha Giken Co., Ltd., and printed on iBest paper using the ink HYECOOB Beni MZ manufactured by Toyo Ink and a 1% solution of fountain solution lysoferro manufactured by Mitsubishi Heavy Industries. Printing was started at a speed of 3500 sheets / hour. A halftone dot image was printed on the paper from the first sheet of printing.
[0076]
(8) Play
Next, an embodiment related to plate reproduction will be described.
After printing is completed, the entire surface of the plate, on which the ink, dampening water, paper powder, and the like adhering to the plate have been wiped clean, is irradiated with infrared rays, and the plate surface temperature is instantaneously increased to about 100 ° C. Illuminance 5mW / cm ² For 8 seconds (irradiation energy of 0.04 J / cm ² ). Then, the contact angle of water 6 was immediately measured with the contact angle meter for the portion where the halftone dot was written, and the contact angle was 8 °, indicating that the plate surface was sufficiently hydrophilic and the history of the plate could be erased. It was confirmed.
[0077]
Next, the 1,2-epoxydodecane solution was roll-coated on the plate surface, and dried at 60 ° C. for 10 minutes. After measuring the contact angle of water 6 with the contact angle meter, the contact angle was 84 °, which was sufficient. The plate material 5 exhibited excellent hydrophobicity, returned to the "initial state at the time of plate preparation", and it was confirmed that the plate could be reproduced.
[0078]
[B] Comparative example
A plate material was produced in the same manner as in the above example, except that the photocatalyst layer 3 was formed directly on the stainless steel substrate 1. That is, a plate material was produced without providing the water storage layer 2.
[0079]
With respect to the plate material of this comparative example, the change of the hydrophilization energy with respect to the plate surface temperature was measured in the same manner as in the above-mentioned example. FIG. 3 shows the measurement results.
As shown by the dotted line in FIG. ₂ Photocatalyst layer 3 / stainless steel substrate 1), hydrophilicity energy at plate surface temperature 25 ° C. is 0.15 J / cm ² However, at a plate surface temperature of 100 ° C., 0.35 J / cm ² 0.9 J / cm at plate temperature of 200 ° C ² Met. Thus, it can be seen that the higher the plate surface temperature, the larger the hydrophilizing energy (the activation light irradiation energy required for hydrophilizing) is required.
[0080]
Similarly to the embodiment, an image was written using the UV setter 710 with an exposure time of 0.1 second for one area (total time of image writing was 24 seconds). When the contact angle of water 6 on the plate after the writing was completed was measured by the contact angle meter, the contact angle of the written portion was still 68 ° and the hydrophobicity was still high. ) Attach it to Alpha Akiken's New Ace Pro desktop offset printing machine and print it on iBest paper at a printing speed of 3500 sheets / hour using Toyo Ink's HYECOOB Red MZ and Mitsubishi Heavy Industries' dampening solution lysoferro 1% solution. As a result of printing, the ink also adhered to the portion that should originally be a non-image area, and only so-called “solid” printing in which red ink adhered to the entire surface could be performed.
[0081]
In order to perform the above printing and plate reproduction on a printing press, it is preferable to use a printing press 10 as shown in FIG.
That is, the printing press 10 includes a plate cleaning device 12, an image writing device 13, a plate surface hydrophobizing device 14, a plate surface heating device 15, a hydrophilic surface active light irradiation device 16, An inking roller 17, a dampening solution supply device 18, and a blanket cylinder 19 are provided. Further, the printing plate material 5 is installed by being wound around the printing drum 11.
[0082]
The process of deleting the history of the plate after printing is completed and the process of reproducing the plate are performed in the printing press 10 as follows.
First, the plate cleaning device 12 is brought into contact with the plate cylinder 11, and the ink, dampening solution, paper powder, and the like adhering to the plate surface are wiped clean. Here, a device having a mechanism for winding a cloth tape for wiping ink is shown as the plate cleaning device 12, but the present invention is not limited to this.
[0083]
Thereafter, the plate cleaning device 12 is detached from the plate cylinder 11, and the plate surface is made hydrophilic by irradiating the entire surface of the plate with actinic light by the active light irradiating device 16 for hydrophilic treatment while heating the plate surface with the plate surface heating device 15. As the active light, ultraviolet light having a wavelength of 360 nm was used in the examples, but light having a wavelength of 400 nm to 600 nm may be used when the photocatalyst shows activity even with light having a wavelength of 400 nm to 600 nm.
[0084]
The plate surface hydrophobicizing device 14 irradiates the plate surface with an energy flux such as light or electricity singly or in combination, applies mechanical stimulus such as friction to the plate surface, or removes an organic compound interacting with the plate surface. By supplying the printing plate, the printing plate is made hydrophobic. Although FIG. 7 shows a roller coating device for supplying an organic compound to the plate surface, the present invention is not limited to this.
[0085]
Next, based on the digital data of the image prepared in advance, the image writing device 13 irradiates the plate surface with active light to write the non-image area.
After writing the image, the inking roller 17, the dampening solution supply device 18, and the blanket cylinder 19 are brought into contact with the plate cylinder 11 so that the paper 20 contacts the blanket cylinder 19. Then, the dampening solution and the ink are sequentially supplied to the plate surface by rotating in the directions of the arrows shown in FIG.
[0086]
In the printing press 10, a series of steps of cleaning the printing plate after printing, erasing the image area by irradiating with actinic light, making the printing plate hydrophobic, regenerating the printing plate for image writing, and preparing the printing plate are performed by using the printing material 5 as a printing machine. Can be carried out on the printing press 10 while being attached to the printer. Accordingly, it is possible to perform a continuous printing operation without stopping the printing press 10 and without interposing plate exchange operations.
[0087]
The printing press 10 is configured to wind the plate material 5 around the plate cylinder 11. However, the present invention is not limited to this, and the water storage layer 2 and the photocatalyst layer 3 are directly placed on the surface of the plate cylinder 11. Needless to say, it is also possible to use a unit provided with the plate cylinder 11 and the plate material 5 integrally.
As described above, the layered composition 5 according to the present embodiment includes the layer 2 containing the substance having a water storage function between the base material 1 and the photocatalyst layer 3, so that the photocatalytic activity is increased by heating. Under the atmosphere, it can be greatly improved, and the surface of the photocatalyst layer 3 can be rapidly hydrophilized.
[0088]
Therefore, when the above-mentioned layered structure 5 is applied to a lithographic printing plate material, it is possible to reuse the plate material, and furthermore, by writing an image with active light in a heating atmosphere, it is possible to write an image. You can save time. Alternatively, the activation light irradiation energy required for hydrophilization can be reduced, so that a low-output writing device can be used and the device cost can be reduced.
[0089]
In addition, by erasing the image history of the plate surface by irradiating with actinic light in a heated atmosphere, it is possible to reduce the time required for erasing the image history. Alternatively, similarly to the above, since the activation light irradiation energy required for hydrophilization can be reduced, a low-output image history erasing apparatus can be used, and the apparatus cost can be reduced.
Since high photocatalytic activity can be expressed in a heated atmosphere in this way, by converting the characteristics of the surface of the photocatalyst layer 3 from hydrophobic to hydrophilic (switching), it is possible to produce a plate, Regardless of whether the history of the plate is erased, there is an advantage that the operation for realizing these operations does not take much time and the cycle of plate production and plate reproduction can be accelerated.
[0090]
In addition, 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 erasure, and the plate material can be easily handled.
[0091]
【The invention's effect】
As described in detail above, according to the layered composition of the present invention, high photocatalytic activity can be exhibited in a heated atmosphere, and the surface of the photocatalytic layer can be rapidly hydrophilized.
Therefore, if the layered composition is applied to a lithographic printing plate material, the time occupied in the printing process, in particular, the image writing time and the image history erasing time can be greatly reduced, and the printing preparation time can be reduced.
In addition, since image writing can be performed with light having a wavelength of visible light to ultraviolet light, there is an advantage that options of a writing device are widened.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a layered structure as one embodiment of the present invention, in which the surface shows hydrophobicity.
FIG. 2 is a schematic cross-sectional view showing a layered composition as one embodiment of the present invention, in which the surface shows hydrophilicity.
FIG. 3 is a graph showing a change in hydrophilization energy with respect to a plate surface temperature of a layered component according to an embodiment of the present invention, where a solid line indicates “photocatalyst layer / water storage layer / substrate” and a dotted line indicates “photocatalyst layer”. Layer / substrate ".
FIG. 4 is a conceptual diagram showing a procedure for producing and reproducing a plate using a planographic printing plate material according to an embodiment of the present invention.
FIG. 5 is a schematic perspective view showing an example of a planographic printing plate material according to an embodiment of the present invention.
FIG. 6 is a graph showing the relationship between the contact angle of water on the surface of a lithographic printing plate material according to one embodiment of the present invention and time (or operation).
FIG. 7 is a diagram schematically showing a printing machine that performs printing and plate reproduction using a lithographic printing plate material according to an embodiment of the present invention.
[Explanation of symbols]
1 Substrate
2 Water storage layer (water storage layer) containing substances with water storage function
3 Photocatalyst layer containing photocatalyst (photocatalyst layer)
3a Photocatalyst layer (non-image area)
3b Photocatalyst layer (image area)
5 Layered components, planographic printing plate materials
6 water
10 printing press
11 plate cylinder
12 Plate cleaning device
13 Image writing device
14 Plate surface hydrophobizing device
15 Plate surface heating device
16 Active light irradiation device for hydrophilization treatment
17 Inking roller
18 dampening water supply device
19 Blanket body
20 paper

Claims (12)

It has a photocatalyst layer containing a photocatalyst, and by irradiating active light having energy larger than the band gap energy of the photocatalyst, the ability to decompose organic compounds present on the photocatalyst layer surface and the photocatalyst layer surface A layered composition that simultaneously exhibits the ability to become hydrophilic,
A layered structure comprising a water storage layer containing a substance having a water storage function between a substrate and the photocatalyst layer. The layered component according to claim 1, wherein the substance having a water storage function is a silica-based compound. 3. The layered composition according to claim 1, wherein the photocatalyst is a titanium oxide photocatalyst or a visible light responsive titanium oxide photocatalyst. A method for producing a layered composition according to any one of claims 1 to 3,
A method for producing a layered component, comprising: forming the water storage layer on the substrate, and then forming the photocatalyst layer on the water storage layer. An image writing and an image history erasing are performed by irradiating the surface of the photocatalyst layer with the active light in a heating atmosphere, comprising the layered composition according to any one of claims 1 to 3, and a reproduction use. A lithographic printing plate material characterized in that: 6. The lithographic printing plate material according to claim 5, wherein at the time of writing the image and erasing the image history, at least a part of the surface of the photocatalytic layer is converted from hydrophobic to hydrophilic. The lithographic printing plate material according to claim 5, wherein the active light is light having a wavelength of 600 nm or less. The surface of the photocatalyst layer is irradiated with light or electricity energy flux alone or in combination, and the friction is applied to the surface of the photocatalyst layer, and the organic compound interacting with the surface of the photocatalyst layer is The lithographic printing plate material according to any one of claims 5 to 7, wherein the surface of the photocatalyst layer is hydrophobized by any of the following: being supplied to the surface of the photocatalyst layer. A method for producing a lithographic printing plate according to any one of claims 5 to 8,
A method for producing a lithographic printing plate material, comprising forming the water storage layer on the base material and then forming the photocatalyst layer on the water storage layer. A plate cylinder to which the lithographic printing plate material according to claim 8 is attached,
A hydrophobizing device for hydrophobizing the photocatalytic layer surface,
An image writing device for writing an image by irradiating the hydrophobicized photocatalyst layer surface with active light of 600 nm or less;
After printing, a plate cleaning device for removing the ink applied to the photocatalyst layer surface,
After removing the ink, an image history erasing device that irradiates the photocatalyst layer surface with the active light to hydrophilize the photocatalyst layer surface and erase the image history on the photocatalyst layer surface,
A printing machine, comprising: a heating device for heating the surface of the photocatalyst layer at the time of irradiating the active light. The printing machine according to claim 10, wherein the heating device heats the photocatalyst layer surface by light irradiation. The printing machine according to claim 10, wherein the heating device heats the surface of the photocatalyst layer by electric heating.

Images