Method for manufacturing lithographic printing plate, method for manufacturing printed matter, and pretreatment solution for lithographic printing plate

Abstract

The present invention provides a method for manufacturing a lithographic printing plate comprising an exposure step of irradiating a lithographic printing plate precursor having at least a photosensitive layer and an ink repulsion layer on a substrate with light to form a latent image, a pretreatment step of bringing the lithographic printing plate precursor on which the latent image is formed into contact with a pretreatment liquid, and a development step of removing the ink repulsion layer of the latent image part, wherein said pretreatment liquid contains an amine compound and water, and the water content is 2‒30% by mass. Provided is a method for manufacturing a lithographic printing plate that has excellent image reproducibility and that makes it possible to suppress peeling of an ink repulsion layer of a non-image part during printing.

Description

Method for producing a lithographic printing plate, method for producing a printed matter, and pretreatment liquid for a lithographic printing plate

[0001] The present invention relates to a method for producing a lithographic printing plate, a method for producing a printed matter, and a pretreatment liquid for a lithographic printing plate.

[0002] Waterless lithographic printing is a printing method that uses a lithographic printing plate that has ink-receptive image areas and ink-repellent non-image areas on nearly the same plane, exploiting the difference in ink adhesion properties to apply ink only to the image areas, and then transfers the ink to the printed material. Because it does not require dampening water to achieve ink-repellency, it has attracted attention as a printing method that reduces environmental impact.

[0003]

[0003] As a method for producing a lithographic printing plate used in waterless lithographic printing, a method has been proposed that includes an exposure step in which a lithographic printing plate precursor is irradiated with light to form a latent image, a pretreatment step in which the lithographic printing plate precursor on which the latent image has been formed is brought into contact with a pretreatment liquid, and a development step in which the ink-repellent layer in the latent image area is removed. The pretreatment step is a step that makes it easier to remove the ink-repellent layer in the latent image area in the development step, and various pretreatment liquids have been studied from the viewpoints of energy efficiency and productivity. For example, proposed are a treatment liquid for waterless lithographic printing plates that contains an ethylene glycol derivative having a specific structure and an amino compound having two or more primary amino groups in one molecule (see, for example, Patent Document 1), and a pretreatment liquid for waterless lithographic printing plates that contains (1) a glycol compound (I), (2) an amino compound having two or more primary amino groups and having an alkylene oxide or alkylene main skeleton, and (3) a glycol derivative (II), in which the content of the (2) amino compound in 100% by weight of the pretreatment liquid is 6% by weight or more and 50% by weight or less, and the composition ratio of the (1) glycol compound and the (3) glycol derivative is 10:1 to 2:1 (parts by weight) (see, for example, Patent Document 2).

[0004] JP 2008-15065 A JP 2019-66591 A

[0005] The pretreatment liquids described in Patent Documents 1 and 2 can improve image reproducibility by using an amino compound. However, in recent years, there has been a demand for higher-resolution printing, and further improvements in the sensitivity and image reproducibility of lithographic printing plates have also been studied. Lithographic printing plates with high sensitivity and excellent image reproducibility tend to have their ink-repellent layer easily removed in the development process, and when pretreatment is performed using a conventionally known pretreatment liquid, the ink-repellent layer in non-image areas is easily peeled off during printing, resulting in the problem of ink being deposited in the non-image areas.

[0006] Therefore, an object of the present invention is to provide a method for producing a lithographic printing plate and a pretreatment liquid for a lithographic printing plate that are excellent in image reproducibility and can suppress peeling of the ink-repellent layer in non-image areas during printing.

[0007] In order to solve the above problems, the present invention mainly has the following configurations: <1> A method for producing a lithographic printing plate, comprising: an exposure step of irradiating a lithographic printing plate precursor having at least a photosensitive layer and an ink-repellent layer on a substrate with light to form a latent image; a pretreatment step of contacting the lithographic printing plate precursor on which the latent image has been formed with a pretreatment liquid; and a development step of removing the ink-repellent layer in the latent image area; wherein the pretreatment liquid contains an amine compound and water, and the water content is 2 to 30 mass%. <2> The method for producing a lithographic printing plate according to <1>, wherein the pretreatment liquid has an amine value of 25 to 45 mgKOH / g. <3> The method for producing a lithographic printing plate according to <1> or <2>, wherein the pretreatment liquid further contains a glycol compound and / or a glycol ether compound. <4> The method for producing a lithographic printing plate according to any one of <1> to <3>, wherein the photosensitive layer of the lithographic printing plate precursor contains a photothermal conversion substance. <5> The method for producing a lithographic printing plate according to <4>, wherein the photosensitive layer of the lithographic printing plate precursor contains a compound having an active hydrogen group. <6> The method for producing a lithographic printing plate according to <5>, wherein the compound having an active hydrogen group contains a triphenylmethane dye and / or a cellulose derivative. <7> A method for producing a printed matter, comprising the steps of depositing ink on an image area of ​​a lithographic printing plate obtained by the method according to any one of <1> to <6>, and transferring the ink to a substrate directly or via a blanket. <8> A pretreatment liquid for a lithographic printing plate, comprising an amine compound and water, the water content being 2 to 30% by mass. <9> The pretreatment liquid for a lithographic printing plate according to <8>, wherein the amine value of the pretreatment liquid is 25 to 45 mgKOH / g. <10> The pretreatment liquid for a lithographic printing plate according to <8> or <9>, further containing a glycol compound and / or a glycol ether compound.

[0008] According to the present invention, a lithographic printing plate can be obtained which has excellent image reproducibility and is capable of suppressing peeling of the ink repellent layer in non-image areas during printing.

[0009] The method for producing a lithographic printing plate of the present invention includes an exposure step of irradiating a lithographic printing plate precursor having at least a photosensitive layer and an ink-repellent layer on a substrate with light to form a latent image, a pretreatment step of contacting the lithographic printing plate precursor on which the latent image has been formed with a pretreatment liquid, and a development step of removing the ink-repellent layer from the latent image area.

[0010] The exposure process is a process in which light is irradiated onto desired locations on the photosensitive layer, causing changes in the photosensitive layer in the areas exposed to the light and forming a latent image. The areas where the latent image is formed are called latent image areas. The latent image areas become ink-receptive image areas because the ink-repellent layer is removed in the development process (described later) due to improved removability of the ink-repellent layer.

[0011] The pretreatment step is a step that makes it easier to remove the ink-repellent layer in the latent image area in the development step. Generally, if development is performed without the pretreatment step, the ink-repellent layer in the latent image area is not sufficiently removable, and the ink-repellent layer remains in the latent image area, making it difficult to form fine image areas. On the other hand, if the lithographic printing plate precursor on which a latent image has been formed is brought into contact with a pretreatment liquid in the pretreatment step, the pretreatment liquid penetrates the ink-repellent layer and reduces the adhesive strength between the ink-repellent layer and the photosensitive layer. Therefore, by providing a pretreatment step, the ink-repellent layer in the latent image area can be more easily removed in the development step, thereby improving the image reproducibility of the lithographic printing plate.

[0012] The development process is a process in which the ink-repellent layer in the latent image area is removed. The photosensitive layer in the area where the ink-repellent layer has been removed becomes an ink-receptive image area. The area where the ink-repellent layer remains becomes a non-image area.

[0013] First, the lithographic printing plate precursor used in the present invention will be described. The lithographic printing plate precursor is a precursor before forming image areas and non-image areas on a lithographic printing plate, and has at least a photosensitive layer and an ink-repellent layer on a substrate. Furthermore, a primer layer may be provided between the substrate and the photosensitive layer.

[0014] The substrate has the function of maintaining the shape of the lithographic printing plate precursor or lithographic printing plate.

[0015] The photosensitive layer functions to form a latent image by irradiating it with light, partially removing the ink-repellent layer in the latent image area, thereby forming an image area on the lithographic printing plate. The latent image is formed when the photosensitive layer undergoes a chemical change due to light, or when the photosensitive layer absorbs light, generates heat, and then undergoes a chemical change due to the heat. The photosensitive layer preferably has the function of absorbing light, generating heat, and then undergoing a chemical change due to the heat, and preferably the generated heat decomposes at least the surface of the photosensitive layer, increases its solubility in a developer, or reduces its adhesive strength with the ink-repellent layer.

[0016] The ink-repellent layer has the function of repelling ink and forms non-image areas on the lithographic printing plate.

[0017] The primer layer has excellent adhesiveness to the substrate and / or the photosensitive layer, and has the function of stabilizing the adhesion between the substrate and the photosensitive layer.

[0018] Examples of substrates include dimensionally stable paper, metal plates, glass plates, and films, which have traditionally been used as substrates for printing plates. Among these, aluminum plates are preferred because they are extremely dimensionally stable during the printing process. Polyethylene terephthalate films are also preferred as flexible substrates for light printing.

[0019] The thickness of the substrate can be appropriately selected depending on the printing machine used for lithographic printing.

[0020] Examples of the primer layer include layers exemplified as heat insulating layers in JP-A Nos. 2004-199016 and 2004-334025.

[0021] As described above, the photosensitive layer preferably absorbs the light used for drawing and generates heat, i.e., converts light into heat (photothermal conversion), and the generated heat decomposes at least the surface of the photosensitive layer, increases its solubility in the developer, or reduces its adhesive strength with the ink-repellent layer. Such a photosensitive layer preferably contains a compound having an active hydrogen group, a crosslinking agent, and a photothermal conversion substance, which can improve the image reproducibility of the lithographic printing plate and further suppress peeling of the ink-repellent layer during printing. The compound having an active hydrogen group can form a salt with an amine compound in the pretreatment solution in the pretreatment step described below. Therefore, in the latent image area formed in the exposure step described below, the pretreatment solution penetrates the ink-repellent layer in the pretreatment step and forms a salt with the photosensitive layer, thereby reducing the adhesive strength between the ink-repellent layer and the photosensitive layer. This facilitates removal of the ink-repellent layer in the image area during the development step, thereby further improving the image reproducibility of the lithographic printing plate. The crosslinking agent promotes crosslinking of the photosensitive layer in non-image areas and improves chemical resistance, thereby further suppressing peeling of the ink-repellent layer during printing. Photothermal conversion substances have the function of converting light into heat (photothermal conversion) during the exposure process. The generated heat can decompose the crosslinked structure composed of a compound having an active hydrogen group and a crosslinking agent. This can further reduce the adhesive strength between the ink-repellent layer and the photosensitive layer in the latent image area, making it easier to remove the ink-repellent layer in the image area during the development process, thereby further improving the image reproducibility of the lithographic printing plate.

[0022] Examples of compounds having an active hydrogen group include triphenylmethane dyes, cellulose derivatives, and polymers having an active hydrogen group. Two or more of these may be contained. Among these, triphenylmethane dyes and cellulose derivatives are preferred because they undergo thermal decomposition due to the heat generated, thereby further reducing the adhesive strength between the ink-repellent layer and the photosensitive layer in the image area and further improving the image reproducibility of the lithographic printing plate. Furthermore, polymers having an active hydrogen group are preferred because they can improve the adhesiveness to the underlying layer (substrate or primer layer).

[0023] Because triphenylmethane dyes and cellulose derivatives generally have low molecular weights, they tend to reduce the crosslinking density of the photosensitive layer and increase the solubility of the pretreatment liquid. Therefore, when triphenylmethane dyes and / or cellulose derivatives are used as compounds having active hydrogen groups, contact with a conventionally known pretreatment liquid results in a significant decrease in the adhesive strength between the photosensitive layer and the ink-repellent layer, leading to problems such as partial peeling of the ink-repellent layer during development or printing and ink deposition in non-image areas. In the present invention, a pretreatment liquid containing 2 to 30% by mass of water is used, thereby suppressing penetration of the pretreatment liquid into the ink-repellent layer and preventing a significant decrease in the adhesive strength between the photosensitive layer and the ink-repellent layer, thereby achieving both improved image reproducibility and suppression of peeling of the ink-repellent layer in non-image areas during printing.

[0024] Examples of triphenylmethane dyes include phenolphthalein, methyl violet, ethyl violet, crystal violet lactone, thymolphthalein, basic fuchsin, light green SF yellow, basic red 9, cresol red, malachite green oxalate, brilliant green, Victoria blue B, crystal violet, bromocresol purple, bromocresol green sodium, thymol blue, bromocresol green, bromothymol blue sodium, tetrabromophenol blue, and bromothymol blue. Two or more of these may be contained. Among these, bromothymol blue sodium and bromothymol blue are preferred, as they can further improve the image reproducibility of the lithographic printing plate.

[0025] The content of the triphenylmethane dye in the photosensitive layer is preferably 0.1 to 40% by mass. By including 0.1% by mass or more of the triphenylmethane dye, sensitivity can be further improved. The content of the triphenylmethane dye is more preferably 1.0% by mass or more, and even more preferably 3.0% by mass or more. On the other hand, by including 40% by mass or less of the triphenylmethane dye, the solvent resistance of the photosensitive layer can be improved and peeling of the photosensitive layer during printing can be suppressed. The content of the triphenylmethane dye is more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0026] Examples of cellulose derivatives include ethyl cellulose, nitrocellulose, etc. Among these, nitrocellulose is preferred, as it can further improve the image reproducibility of the lithographic printing plate.

[0027] The content of the cellulose derivative in the photosensitive layer is preferably 0.1% by mass to 40% by mass. By containing 0.1% by mass or more of the cellulose derivative, sensitivity can be further improved. The content of the cellulose derivative is more preferably 1.0% by mass or more, and even more preferably 3.0% by mass or more. On the other hand, by containing 40% by mass or less of the cellulose derivative, the solvent resistance of the photosensitive layer can be improved and peeling of the photosensitive layer during printing can be suppressed. The content of the cellulose derivative is more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0028] Examples of polymers having active hydrogen groups include polyurethanes, polyureas, polyamides, epoxy resins, polyalkyleneimines, novolac resins, resol resins, and melamine resins. Two or more of these may be used. Melamine resins also include methylated melamine resins, which are obtained by further reacting melamine resins with methanol to convert methylol groups to methoxymethyl groups.

[0029] Among these, polymers having an alcoholic hydroxyl group, a phenolic hydroxyl group, or a carboxyl group are preferred, polymers having a phenolic hydroxyl group (such as a homopolymer or copolymer of p-hydroxystyrene, a novolac resin, or a resol resin) are more preferred, and novolac resins are even more preferred. Examples of novolac resins include phenol novolac resins and cresol novolac resins.

[0030] The content of the polymer having an active hydrogen group in the photosensitive layer is preferably 20 to 80% by mass. By containing 20% ​​by mass or more of the polymer having an active hydrogen group, it is possible to improve developability. The content of the polymer having an active hydrogen group is more preferably 40% by mass or more. On the other hand, by containing 80% by mass or less of the polymer having an active hydrogen group, it is possible to maintain the toughness of the photosensitive layer. The content of the polymer having an active hydrogen group is more preferably 70% by mass or less.

[0031] As the crosslinking agent, a compound having a plurality of functional groups reactive with active hydrogen groups is preferred.For example, polyfunctional isocyanate compounds, polyfunctional blocked isocyanate compounds, polyfunctional epoxy compounds, polyfunctional (meth)acrylate compounds, polyfunctional aldehyde compounds, polyfunctional mercapto compounds, polyfunctional alkoxysilyl compounds, polyfunctional amine compounds, polyfunctional carboxylic acids, polyfunctional vinyl compounds, polyfunctional diazonium salts, polyfunctional azide compounds, hydrazine, metal chelate compounds, metal alkoxide compounds, etc.Can contain two or more of these.Among these, from the viewpoint of reactivity with active hydrogen groups, compounds selected from polyfunctional amine compounds, metal chelate compounds and metal alkoxide compounds are preferred, and metal chelate compounds are more preferred.

[0032] The content of the crosslinking agent in the photosensitive layer is preferably 1 to 30% by mass. By including 1% or more by mass of the crosslinking agent, chemical resistance can be improved. The content of the crosslinking agent is more preferably 5% by mass or more. On the other hand, by including 30% or less by mass of the crosslinking agent, high sensitivity can be maintained. The content of the crosslinking agent is more preferably 20% or less by mass.

[0033] The photothermal conversion substance is preferably one that absorbs laser light, converts light energy into atomic / molecular kinetic energy, and instantaneously generates heat of 200°C or higher on the surface of the photosensitive layer, thereby thermally decomposing the crosslinked structure of the photosensitive layer, and is particularly preferably a pigment or dye that absorbs infrared or near-infrared light. Two or more of these may be contained.

[0034] Examples of pigments that absorb infrared or near-infrared rays include black pigments such as carbon black, carbon graphite, aniline black, and cyanine black; phthalocyanine and naphthalocyanine green pigments; inorganic compounds containing crystal water; metal powders of iron, copper, chromium, bismuth, magnesium, aluminum, titanium, zirconium, cobalt, vanadium, manganese, and tungsten; and sulfides, hydroxides, silicates, sulfates, phosphates, diamine compound complexes, dithiol compound complexes, phenolthiol compound complexes, and mercaptophenol compound complexes of these metals.

[0035] Examples of dyes that absorb infrared or near-infrared light include dyes for electronics or recording, which have a maximum absorption wavelength in the range of 700 nm to 1500 nm, such as cyanine dyes, azulenium dyes, squarylium dyes, croconium dyes, azo disperse dyes, bisazostilbene dyes, naphthoquinone dyes, anthraquinone dyes, perylene dyes, phthalocyanine dyes, naphthalocyanine metal complex dyes, polymethine dyes, dithiol nickel complex dyes, indoaniline metal complex dyes, intermolecular CT dyes, benzothiopyran spiropyrans, and nigrosine dyes. Among these, dyes selected from cyanine dyes, azo disperse dyes, naphthoquinone dyes, and phthalocyanine dyes are preferred from the viewpoint of sensitivity to light during the exposure step.

[0036] The content of the photothermal conversion substance in the photosensitive layer is preferably 5 to 50% by mass. By including 5% or more by mass of the photothermal conversion substance, sensitivity can be improved. The content of the photothermal conversion substance is more preferably 10% by mass or more. On the other hand, by including 50% or less by mass of the photothermal conversion substance, crosslinking of the photosensitive layer can be promoted and high printing durability can be maintained.

[0037] The thickness of the photosensitive layer is preferably 0.1 to 5 μm. By making the thickness of the photosensitive layer 0.1 μm or more, sensitivity can be improved and image reproducibility can be further improved. On the other hand, by making the thickness of the photosensitive layer 5 μm or less, high printing durability can be maintained.

[0038] The ink-repellent layer is preferably a silicone rubber layer which is a crosslinked product of polyorganosiloxane, and examples thereof include silicone rubber layers of addition reaction type, condensation reaction type, and combination of addition reaction and condensation reaction type. Of these, an addition reaction type silicone rubber layer is preferred.

[0039] Examples of silicone rubber layers of the addition reaction type, condensation reaction type, or combined addition reaction-condensation reaction type include layers exemplified as diorganosiloxane unit-containing layers in JP 2021-66175 A, layers exemplified as silicone rubber layers in WO 2019 / 203261, and layers exemplified as first silicone layers in WO 2019 / 203263.

[0040] The ink-repellent layer preferably contains an ink-repellent liquid, which can appropriately reduce the elastic modulus of the printing plate surface and prevent brittle fracture of the ink-repellent layer.

[0041] The content of the ink-repellent liquid in the ink-repellent layer is preferably 4% by mass or more from the viewpoint of partially inhibiting crosslinking and further reducing the plate surface elasticity, while the content of the ink-repellent liquid in the ink-repellent layer is preferably 14% by mass or less, more preferably 12% by mass or less, from the viewpoint of maintaining the plate surface elasticity.

[0042] The ink-repellent liquid is preferably a silicone compound, more preferably a silicone oil. The silicone oil in the present invention refers to a free polysiloxane component that is not involved in crosslinking of the ink-repellent layer. Examples of silicone oils include those exemplified as silicone oils in International Publication No. 2016 / 076286.

[0043] The thickness of the ink-repellent layer is preferably 1.0 to 10.0 μm. By making the thickness of the ink-repellent layer 1.0 μm or more, printing durability can be improved. On the other hand, by making the thickness of the ink-repellent layer 10 μm or less, image reproducibility can be further improved.

[0044] The lithographic printing plate precursor can be obtained, for example, by forming a primer layer, a photosensitive layer and an ink-repellent layer, if necessary, on a substrate.

[0045] The photosensitive layer can be formed, for example, by applying a solution or dispersion containing the components constituting the photosensitive layer described above, and drying it as necessary. Drying may be performed at room temperature or by heating. When heating, the heating temperature is preferably 50 to 180°C.

[0046] The ink-repellent layer can be formed, for example, by applying a solution containing the components constituting the ink-repellent layer described above and drying it as needed. Drying may be carried out at room temperature or by heating. When heating, the heating temperature is preferably 50 to 200°C. Examples of coating devices for each layer include coaters such as reverse roll coaters, air knife coaters, gravure coaters, and die coaters, as well as rotary coating devices. Thereafter, a protective film or slip sheet may be laminated as needed.

[0047] Next, the exposure step will be described. In the exposure step, the above-mentioned lithographic printing plate precursor is irradiated with light to form a latent image. For example, by irradiating the area of ​​the lithographic printing plate precursor where an image area is to be formed with light, the adhesive strength between the photosensitive layer and the ink-repellent layer in that area is reduced, and the ink-repellent layer can be removed in the development step described below. When the lithographic printing plate precursor has a protective film, the exposure may be performed from above the protective film, or the protective film may be peeled off and then the exposure may be performed.

[0048] The light source used in the exposure step is preferably one having an emission wavelength region in the range of 300 nm to 1,500 nm. Semiconductor lasers and YAG lasers having an emission wavelength region near the near-infrared region are preferred because they are widely used as the absorption wavelength of the photosensitive layer, and laser light having a wavelength of 780 nm, 830 nm, or 1,064 nm is preferred from the viewpoint of light-to-heat conversion efficiency.

[0049] Next, the pretreatment step will be described. In the pretreatment step, the lithographic printing plate precursor on which a latent image has been formed in the exposure step is brought into contact with a pretreatment liquid. This allows the pretreatment liquid to penetrate the ink-repellent layer and form a salt with the photosensitive layer, thereby reducing the adhesive strength between the ink-repellent layer and the photosensitive layer. This makes it easier to remove the ink-repellent layer in the latent image area in the development step, thereby improving the image reproducibility of the lithographic printing plate.

[0050] The pretreatment liquid for a lithographic printing plate of the present invention is characterized by containing an amine compound and water, with the water content being 2 to 30% by mass. By containing an amine compound, the pretreatment liquid penetrates the ink-repellent layer, reducing the adhesive strength between the ink-repellent layer and the photosensitive layer, thereby improving the image reproducibility of the lithographic printing plate. In particular, when the photosensitive layer contains a compound having an active hydrogen group, the pretreatment liquid penetrates the ink-repellent layer and the amine compound forms a salt with the active hydrogen group in the photosensitive layer, thereby achieving this effect more significantly. Furthermore, by containing water, the amine compound forms hydroxide ions, promoting salt formation between the amine compound and the active hydrogen group in the photosensitive layer, thereby further improving the image reproducibility of the lithographic printing plate.

[0051] On the other hand, by including water in the pretreatment liquid, it is possible to appropriately suppress the penetration of the pretreatment liquid into the ink-repellent layer, suppress a decrease in adhesion between the photosensitive layer and the ink layer in non-image areas, improve chemical resistance, and suppress peeling of the ink-repellent layer during printing. The water content in the pretreatment liquid is 2 to 30% by mass. If the water content is less than 2% by mass, the ink-repellent layer is likely to peel during printing, particularly in highly sensitive lithographic printing plates. The water content is preferably 3% by mass or more, and more preferably 5% by mass or more. On the other hand, if the water content exceeds 30% by mass, image reproducibility decreases. The water content is preferably 26% by mass or less, and more preferably 22% by mass or less.

[0052] The water content in the pretreatment solution can be determined by volumetric titration using a Karl Fischer moisture meter. Specifically, first, prepare the Karl Fischer reagent to be used in the Karl Fischer moisture meter. Shake the reagent in the reagent bottle well to homogenize it, then connect it to the moisture meter. Perform burette replacement to wash the reagent bottle, buret, and piping together. Perform reagent titration multiple times to confirm the reagent titer. Next, add anhydrous methanol as a solvent to the titration flask of the moisture meter, and add a weighed amount of pretreatment solution as a sample. When titration begins, the water in the sample reacts with the Karl Fischer reagent, consuming iodine. Titration continues until the amount of iodine consumed becomes constant. The water content in the pretreatment solution can be measured from the titer (mL) of the Karl Fischer reagent at the end of titration using the following formula: Water content (mass%) = {Karl Fischer reagent titer (mL) × titer (mgH ２ 0 / mL) / mass of sample (mg)}×100.

[0053] Examples of the amine compound include compounds having one primary amino group per molecule, compounds having two or more primary amino groups per molecule, and compounds having three or more primary amino groups per molecule. Among these, compounds having a molecular weight of 150 or more are preferred from the viewpoint of volatility. Furthermore, from the viewpoint of further improving image reproducibility, compounds having three or more primary amino groups per molecule are more preferred. Examples of compounds having one primary amino group per molecule include N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, N-(2-hydroxypropyl)N-methylamine, N-(2-hydroxypropyl)N-ethylamine, N-(2-hydroxypropyl)N-propylamine, N-(2-hydroxypropyl)N-butylamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dipropylethanolamine, N,N-dibutylethanolamine, N-(2-hydroxypropyl)N,N- Examples of such an amine include dimethylamine, N-(2-hydroxypropyl)N,N-diethylamine, N-(2-hydroxypropyl)N,N-dipropylamine, N-(2-hydroxypropyl)N,N-dibutylamine, 2-aminoethoxyethanol, methoxypolyethylene glycolamine, poly(ethylene glycol)bis(amine), poly(ethylene glycol)methyl etheramine, trimethylolpropane tris[poly(propylene glycol), amine terminated]ether, 2-(2-(2-methoxyethoxy)ethoxy)ethanamine, and 2-(2-methoxyethoxy)ethanamine.Examples of compounds having two or more primary amino groups in one molecule include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,2-diaminobutane, 1,4-diaminobutane, 2,3-diaminobutane, hexamethylenediamine, diethylenetriamine, triethylenetetramine, bis(3-aminopropyl)ether, iminobis(propylamine), methyliminobispropylamine, bis(3-aminopropyloxy)ethane, N,N-bis(3-aminopropyl)-1,3-propylenediamine, and N,N-bis(3-aminopropyl)-1,4-butylenediamine. Examples of suitable amines include polyoxypropylene diamines (e.g., Jeffamine (registered trademark) D-203, D-400, D-2000, and D-4000, manufactured by HUNTSMAN), 1,2,5-pentatriamine, 2,3,6-triaminopyridine, polyoxyalkylene triamines (e.g., Jeffamine (registered trademark) T-403, T-3000, and T-5000, manufactured by HUNTSMAN), α,ω-bis(3-aminopropyl)diethylene glycol ether, α,ω-bis(3-aminopropyl)polyethylene glycol ether, and 1,2,4,5-benzenetetramine. Examples of compounds having three or more primary amino groups in one molecule include diethylenetriamine, triethylenetetramine, iminobis(propylamine), methyliminobispropylamine, N,N-bis(3-aminopropyl)-1,3-propylenediamine, N,N-bis(3-aminopropyl)-1,4-butylenediamine, 1,2,5-pentatriamine, 2,3,6-triaminopyridine, and polyoxyalkylenetriamines (e.g., Jeffamine (registered trademark) T-403, T-3000, and T-5000, manufactured by HUNTSMAN).

[0054] The content of the amine compound in the pretreatment liquid is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more from the viewpoint of further improving image reproducibility, while the content of the amine compound in the pretreatment liquid is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 12% by mass or less from the viewpoint of further suppressing peeling of the ink-repellent layer during printing.

[0055] The pre-treatment liquid preferably further contains a glycol compound and / or a glycol ether compound. By containing the glycol compound and / or the glycol ether compound in the pre-treatment liquid, the developability of the non-image area can be improved, and image reproducibility can be further improved.

[0056] Examples of glycol compounds include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene glycol, etc. Two or more of these may be contained.

[0057] Examples of glycol ether compounds include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, pentaethylene glycol monomethyl ether, pentaethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tetrapropylene glycol monomethyl ether, tetrapropylene glycol monoethyl ether, pentapropylene glycol monomethyl ether, pentapropylene glycol monoethyl ether, etc. Two or more of these may be contained.

[0058] The total content of glycol compounds and / or glycol ether compounds in the pre-treatment liquid is preferably 5% by mass or more, more preferably 15% by mass or more, from the viewpoint of further improving image reproducibility, while the total content of glycol compounds and / or glycol ether compounds is preferably 95% by mass or less, more preferably 90% by mass or less, from the viewpoint of ensuring sufficient dyeability.

[0059] The pretreatment liquid may further contain a propylene glycol solvent, a dye, a dye assistant, a surfactant, an antifoaming agent, etc., as required.

[0060] The amine value of the pretreatment liquid is preferably in the range of 25 to 45 mgKOH / g. The amine value is an index representing the content of basic nitrogen in the amine compound in the pretreatment liquid, and is the amount of potassium hydroxide (mg) equivalent to the acid required to neutralize 1 g of sample. By increasing the amine value of the pretreatment liquid to 25 mgKOH / g or more, the pretreatment liquid can more efficiently penetrate the ink-repellent layer in the latent image area, reducing the adhesive strength between the ink-repellent layer and the photosensitive layer and further improving the image reproducibility of the lithographic printing plate. In particular, when the photosensitive layer contains a polymer having an active hydrogen group, this effect can be more pronounced by the pretreatment liquid forming a salt with the photosensitive layer. From the viewpoint of further improving image reproducibility, the amine value of the pretreatment liquid is more preferably 28 mgKOH / g or more. On the other hand, by increasing the amine value to 45 mgKOH / g or less, penetration of the amine compound into the unexposed areas (non-image areas) is suppressed. This can further suppress peeling of the ink-repellent layer in the non-image areas during printing. Furthermore, in order to prevent the ink repellent layer from peeling off, it is more preferable that the amine value of the pretreatment liquid is 42 mgKOH / g or less.

[0061] The amine value can be determined by the following method. First, approximately 5 g of the pretreatment solution is weighed out as a sample and dissolved in 50 mL of water. Next, using a potentiometer or pH meter, the resulting solution is titrated with 0.1 mol / L aqueous hydrochloric acid. The inflection point of the titration curve is taken as the endpoint, and the amount of 0.1 mol / L aqueous hydrochloric acid consumed is read. The amine value is calculated using the following formula: Amine value (mg KOH / g) = {(amount of 0.1 mol / L aqueous hydrochloric acid consumed (mL)) / (amount of sample (g))} × 5.611.

[0062] The amine value of the pretreatment liquid can be adjusted to a desired range, for example, by adjusting the content of the amine compound in the pretreatment liquid.

[0063] Next, the developing process will be described. In the developing process, the ink-repellent layer in the latent image area is removed. In the area where the ink-repellent layer has been removed, the photosensitive layer becomes the ink-receptive layer and becomes the image area. In the area where the ink-repellent layer remains, the ink-repellent layer becomes the non-image area.

[0064] Examples of the developing method include a method of rubbing in the presence or absence of a developer, and a so-called peel-off development method in which the ink-repellent layer is peeled off together with the protective film to form an image area. In the former case, it is preferable to carry out the rubbing treatment in the presence of a developer from the viewpoint of suppressing damage to the ink-repellent layer due to the rubbing treatment.

[0065] Examples of developers include water, water to which a surfactant or a polar solvent such as alcohol, ketone, ester, or carboxylic acid has been added, and aliphatic hydrocarbons (hexane, heptane, isoparaffin hydrocarbons, etc.), aromatic hydrocarbons (toluene, xylene, etc.), and halogenated hydrocarbons (trichlene, etc.) to which a polar solvent has been added. The developer may also contain a dye such as crystal violet, Victoria Pure Blue, or Astrazone Red. By including a dye, the image area is colored simultaneously with development, improving plate inspection properties.

[0066] Examples of rubbing treatment methods include (i) wiping the plate surface with a nonwoven fabric, absorbent cotton, cloth, sponge, or the like soaked in a developer; (ii) pretreating the plate surface with a developer and then rubbing it with a rotating brush while showering it with tap water, or the like; and (iii) spraying high-pressure water, hot water, or steam onto the plate surface.

[0067] It is preferable to further include a post-treatment step after the development step in which the image area from which the ink-repellent layer has been removed is colored. The post-treatment step can improve the visibility of the image area and the measurement accuracy of the halftone dots. In the post-treatment step, it is preferable to contact the developed lithographic printing plate with a post-treatment liquid containing a dye such as crystal violet, Victoria Pure Blue, or Astra Red.

[0068] Some or all of the above pretreatment, development, and posttreatment steps can also be carried out continuously using an automatic developing machine. Examples of automatic developing machines include machines with only a development section, machines in which a pretreatment section and a development section are provided in this order, machines in which a pretreatment section, a development section, and a posttreatment section are provided in this order, and machines in which a pretreatment section, a development section, a posttreatment section, and a water washing section are provided in this order. Specific examples of automatic developing machines include the TWL-650 series, TWL-860 series, and TWL-1160 series (all manufactured by Toray Industries, Inc.), and the TWP 680 series and TWP 1250 series (all manufactured by Heights UK Ltd.). These may also be used in combination.

[0069] When developed lithographic printing plates are stored in a stack, it is preferable to place slip sheets between the plates to protect the plate surfaces.

[0070] Next, a method for producing a printed matter will be described. The method for producing a printed matter of the present invention includes the steps of applying ink to the image area of ​​the lithographic printing plate obtained by the above-mentioned method and transferring the ink to a substrate directly or via a blanket. The photosensitive layer, which is the image area, and the ink-repellent layer, which is the non-image area, are substantially flush with each other, but the difference in ink adhesion properties is utilized to apply ink only to the image area, and then the ink is transferred to the substrate. Here, the substrate refers to the medium on which the ink is printed. Examples of substrates include thin paper, cardboard, film, and labels. The ink can be transferred from the lithographic printing plate directly to the substrate, or via a blanket.

[0071] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0072] (Production Example 1: Production of lithographic printing plate precursor PL-1) A lithographic printing plate precursor was produced by the following method. The following primer layer composition solution was applied to a 0.24 mm thick degreased aluminum substrate (manufactured by Mitsubishi Aluminum Corporation) and dried at 200°C for 90 seconds to provide a primer layer with a thickness of 6.0 µm. The primer layer composition solution was obtained by mixing the following components with stirring at room temperature. <Primer layer composition solution> Polymer having active hydrogen: epoxy resin: "Epikote (registered trademark)" 1010 (manufactured by Japan Epoxy Resins Co., Ltd.): 35 parts by mass Polymer having active hydrogen: polyurethane: "Sunpren (registered trademark)" LQ-T1331D (manufactured by Sanyo Chemical Industries, Ltd., solid content concentration: 20% by mass): 375 parts by mass Aluminum chelate: Aluminum chelate ALCH-TR (manufactured by Kawaken Fine Chemicals Co., Ltd.): 10 parts by mass Leveling agent: "Disparlon (registered trademark)" LC951 (manufactured by Kusumoto Chemicals Co., Ltd., solid content: 10% by mass): 1 part by mass Titanium oxide: N,N-dimethylformamide dispersion of "Tipaque (registered trademark)" CR-50 (manufactured by Ishihara Sangyo Kaisha, Ltd.) (titanium oxide 50% by mass): 60 parts by mass N,N-dimethylformamide: 730 parts by mass Methyl ethyl ketone: 250 parts by mass.

[0073] Next, the following photosensitive layer composition solution-1 was applied onto the primer layer and dried by heating at 140°C for 90 seconds to provide a photosensitive layer having a thickness of 1.5 µm. The photosensitive layer composition solution-1 was obtained by mixing the following components with stirring at room temperature. <Photosensitive Layer Composition Solution-1> Photothermal conversion material: NK5559 (manufactured by Hayashibara Co., Ltd., maximum absorption wavelength 774 nm): 12.0 parts by mass Compound having an active hydrogen group: phenol formaldehyde novolak resin: "Sumilite Resin (registered trademark)" PR53195 (manufactured by Sumitomo Bakelite Co., Ltd.): 65.4 parts by mass Compound having an active hydrogen group: bromothymol blue (maximum absorption wavelength 400 to 650 nm, thermal decomposition temperature 202°C, triphenylmethane dye): 7.0 parts by mass Crosslinking agent: titanium-n-butoxide bis(acetylacetonate): "Nacem (registered trademark)" Titanium (manufactured by Nippon Chemical Industry Co., Ltd., concentration: 73% by mass, containing 27% by mass of n-butanol as a solvent): 17.6 parts by mass Tetrahydrofuran: 900 parts by mass.

[0074] Next, the following ink-repellent layer composition solution-1, prepared immediately before coating, was coated on the photosensitive layer and heated at 140°C for 80 seconds to provide an ink-repellent layer with an average film thickness of 3.0 µm, thereby obtaining lithographic printing plate precursor PL-1. Note that ink-repellent layer composition solution-1 was obtained by mixing the following components with stirring at room temperature. <Ink repellent layer composition solution-1> α,ω-divinylpolydimethylsiloxane: DMS-V35 (manufactured by Gelest Inc., weight average molecular weight 49,500): 87.0 parts by mass Silicone oil: KF-96-50cs (polydimethylsiloxane capped with methyl groups at both ends, weight average molecular weight: 3780, surface tension: 20.8 mN / m, boiling point: >150°C, manufactured by Shin-Etsu Chemical Co., Ltd.): 10.0 parts by mass Methylhydrogensiloxane-dimethylsiloxane copolymer (manufactured by Dow Toray Industries, Inc.): 2.95 parts by mass Vinyltris(methylethylketoxyimino)silane: 2.6 parts by mass Platinum catalyst SRX212 (manufactured by Dow Toray Industries, Inc.): 6.2 parts by mass Isoparaffinic hydrocarbon solvent "Isopar (registered trademark)" E (manufactured by ExxonMobil Chemical Corporation): 900 parts by mass.

[0075] (Production Example 2: Production of lithographic printing plate precursor PL-2) Except for changing photosensitive layer composition solution-1 to the following photosensitive layer composition solution-2, lithographic printing plate precursor PL-2 was obtained in the same manner as in the production of lithographic printing plate precursor PL-1 in Production Example 1. Photosensitive layer composition solution-2 was obtained by stirring and mixing the following components at room temperature. <Photosensitive Layer Composition Solution-2> Photothermal conversion material: NK5559 (manufactured by Hayashibara Co., Ltd., maximum absorption wavelength 774 nm, cyanine dye): 12.0 parts by mass Compound having an active hydrogen group: phenol formaldehyde novolak resin: "Sumilite Resin (registered trademark)" PR53195 (manufactured by Sumitomo Bakelite Co., Ltd.): 70.4 parts by mass Crosslinking agent: titanium-n-butoxide bis(acetylacetonate): "Nacem (registered trademark)" Titanium (manufactured by Nippon Chemical Industry Co., Ltd., concentration: 73% by mass, containing 27% by mass of n-butanol as a solvent): 17.6 parts by mass Tetrahydrofuran: 900 parts by mass.

[0076] (Production Example 3: Production of lithographic printing plate precursor PL-3) Except for changing photosensitive layer composition solution-1 to the following photosensitive layer composition solution-3, lithographic printing plate precursor PL-3 was obtained in the same manner as in the production of lithographic printing plate precursor PL-1 in Production Example 1. Photosensitive layer composition solution-3 was obtained by mixing the following components with stirring at room temperature. <Photosensitive Layer Composition Solution-3> Photothermal conversion material: NK5559 (manufactured by Hayashibara Co., Ltd., maximum absorption wavelength 774 nm, cyanine dye): 12.0 parts by mass Compound having an active hydrogen group: phenol formaldehyde novolak resin: SUMILITE RESIN (registered trademark) PR53195 (manufactured by Sumitomo Bakelite Co., Ltd.): 63.4 parts by mass Compound having an active hydrogen group: nitrocellulose DLX5 / 8 (manufactured by Nobel Enterprises, thermal decomposition temperature: 200°C, cellulose derivative): 7.0 parts by mass Crosslinking agent: titanium-n-butoxide bis(acetylacetonate): "Nacem (registered trademark)" Titanium (manufactured by Nippon Chemical Industry Co., Ltd., concentration: 73% by mass, containing 27% by mass of n-butanol as a solvent): 17.6 parts by mass Tetrahydrofuran: 900 parts by mass.

[0077] (Production Example 4: Production of lithographic printing plate precursor PL-4) Except for changing photosensitive layer composition solution-1 to the following photosensitive layer composition solution-4, lithographic printing plate precursor PL-4 was obtained in the same manner as in the production of lithographic printing plate precursor PL-1 in Production Example 1. Photosensitive layer composition solution-4 was obtained by mixing the following components with stirring at room temperature. <Photosensitive Layer Composition Solution-4> Photothermal conversion material: S 0094 (manufactured by FEW Chemicals GmbH): 24.0 parts by mass Compound having an active hydrogen group: methylated melamine resin: CYMEL (registered trademark) 303 (manufactured by Allnex): 53.2 parts by mass Compound having an active hydrogen group: nitrocellulose DLS (registered trademark) E400 NC (manufactured by Dow Chemical): 18.5 parts by mass Sulfonic acid compound: p-toluenesulfonic acid: 4.3 parts by mass Propylene glycol methyl ether: 465 parts by mass N-methylpyrrolidone: 89 parts by mass

[0078] (Production Example 5: Production of pre-treatment liquid PT-1) Pre-treatment liquid PT-1 was obtained by mixing with stirring at room temperature 10.5 parts by mass of "JEFFAMINE (registered trademark)" T-403 (manufactured by HUNTSMAN) (hereinafter referred to as T-403) as an amine compound, 67 parts by mass of diethylene glycol (hereinafter referred to as DEG) as a glycol compound, and 22.5 parts by mass of triethylene glycol monoethyl ether (hereinafter referred to as TEGME) as a glycol ether compound.

[0079] (Production Example 6: Production of pre-treatment liquid PT-2) 10.5 parts by mass of T-403 as an amine compound, 64 parts by mass of DEG and 22.5 parts by mass of TEGME as a glycol compound and a glycol ether compound, and 3 parts by mass of water were mixed with stirring at room temperature to obtain pre-treatment liquid PT-2.

[0080] (Production Examples 7 to 15: Production of Pre-treatment Solutions PT-3 to 11) Pre-treatment solutions PT-3 to 11 were produced in the same manner as in Production Example 6, except that the amounts of the amine compound, glycol compound, glycol ether compound, and water added were changed as shown in Table 1.

[0081] (Production Example 16: Production of pre-treatment liquid PT-12) 15 parts by mass of T-403 as an amine compound, and 85 parts by mass of triethylene glycol (hereinafter referred to as TEG) as a glycol compound and glycol ether compound were mixed with stirring at room temperature to obtain pre-treatment liquid PT-12.

[0082] (Production Example 17: Production of pre-treatment liquid PT-13) 15 parts by mass of T-403 as an amine compound, 60 parts by mass of TEG as a glycol compound, and 30 parts by mass of TEGME as a glycol ether compound were mixed with stirring at room temperature to obtain pre-treatment liquid PT-13.

[0083] (Production Example 18: Production of pre-treatment liquid PT-14) 10.5 parts by mass of T-403 as an amine compound, 66 parts by mass of DEG and 22.5 parts by mass of TEGME as a glycol compound and a glycol ether compound, and 1 part by mass of water were mixed with stirring at room temperature to obtain pre-treatment liquid PT-14.

[0084] (Production Examples 19 to 20: Production of Pre-Treatment Solutions PT-15 to 16) Pre-treatment solutions PT-15 to 16 were produced in the same manner as in Production Example 18, except that the amounts of the amine compound, glycol compound, glycol ether compound, and water added were changed as shown in Table 1.

[0085] The compositions of the pretreatment solutions PT-1 to PT-16 obtained in Production Examples 5 to 20 and the evaluation results according to the methods described below are shown in Table 1.

[0086]

[0087] Next, the evaluation methods used in the examples and comparative examples will be described.

[0088] (1) Water Content Approximately 0.1 g of each of the pretreatment liquids obtained in Production Examples 5 to 20 was precisely weighed, and the moisture content was measured by volumetric titration using a Karl Fischer moisture meter MKV-710 (manufactured by Kyoto Electronics Manufacturing Co., Ltd.).

[0089] First, "Hydranal (registered trademark)"-Composite 5 (manufactured by Honeywell) was prepared as the Karl Fischer reagent to be used in the Karl Fischer moisture meter. The reagent in the reagent bottle was shaken well to homogenize it, and then connected to the moisture meter. Burette replacement was performed to wash the reagent bottle, buret, and piping together. The titer of the reagent was standardized multiple times to confirm its titer. Next, anhydrous methanol was added as a solvent to the titration flask of the moisture meter, and a weighed amount of pretreatment liquid was added as a sample. Titration was started, and the water in the sample reacted with the Karl Fischer reagent, consuming iodine. Titration was continued until the amount of iodine consumed became constant. The water content was calculated from the titer (mL) of the Karl Fischer reagent at the end of titration using the following formula: Water content (mass%) = (Karl Fischer reagent titer (mL) × titer (mgH ２ 0 / mL) / mass of sample (mg) × 100.

[0090] (2) Amine Value Five grams of each of the pretreatment solutions obtained in Production Examples 5 to 20 was weighed out and placed in a beaker, and 45 grams of water was added. While measuring the pH using a desktop pH meter LAQUA-PH-SE (HORIBA, Ltd.), 0.1 mol / L hydrochloric acid (FUJIFILM Wako Pure Chemical Industries, Ltd.) was added dropwise to the resulting solution until the pH reached 7. The amine value was calculated from the amount of pretreatment solution and the amount of 0.1 mol / L hydrochloric acid added dropwise until the pH reached 7, using the following formula: Amine value (mg KOH / g) = {(amount of 0.1 mol / L hydrochloric acid aqueous solution consumed (mL)) / (amount of sample (g))} × 5.611.

[0091] (3) Image reproducibility The 2% halftone dots of the lithographic printing plates obtained in each of the Examples and Comparative Examples were observed at a magnification of 20 times using an optical microscope "ECLIPSE L200N" (manufactured by Nikon Corporation), and the proportion of reproduced halftone dots to the total number of halftone dots (reproducibility) was calculated. If the reproducibility of the 2% halftone dots is 95% or more, the plate can be used without any problems in practice, and if the reproducibility of the 2% halftone dots is 100%, it is more preferable.

[0092] (4) Resistance to Peeling of Ink-Repellent Layer The lithographic printing plates obtained in each of the Examples and Comparative Examples were cut into a size of 300 mm x 100 mm and heated to 30°C using a hot plate.

[0093] A piece of gauze cut to a size of 5 mm x 5 mm was placed on the ink-repellent layer of the lithographic printing plate, and 100 μL of the solution for evaluating the resistance to peeling of the ink-repellent layer was dropped onto the gauze. The solution for evaluating the resistance to peeling of the ink-repellent layer was prepared by mixing and stirring the following components at room temperature. <Solution for evaluating the resistance to peeling of the ink-repellent layer> Dipropylene glycol: 67 parts by mass Tripropylene glycol: 16 parts by mass Diglycolamine: 10 parts by mass Water: 5 parts by mass After a certain period of time had elapsed, the gauze was removed, and the solution for evaluating the resistance to peeling of the ink-repellent layer was wiped off by rubbing the surface of the lithographic printing plate five times with a cotton pad. After wiping, the surface of the lithographic printing plate was visually observed to determine whether or not the ink-repellent layer had peeled off where the gauze had been placed. This evaluation was carried out every 10 seconds, and the ink-repellent layer peeling resistance was evaluated based on the longest time the ink-repellent layer remained unpeeled. This evaluation correlates with the resistance of the ink-repellent layer to peeling during printing, and is positioned as a simple evaluation of the resistance of the ink-repellent layer to peeling during printing. In this evaluation, the longer the longest time in seconds that the ink-repellent layer remained without peeling, the greater the effect of suppressing the ink-repellent layer from peeling. If it is 90 seconds or longer, it can be used without problems in actual printing, if it is 120 seconds or longer, it is more preferable, and if it is 150 seconds or longer, it is even more preferable.

[0094] (5) Resistance to Peeling of Ink-Repellent Layer During Printing A printing tester was prepared by connecting an ultraviolet irradiation device with a built-in variable-speed conveyor to the paper discharge section of a sheet-fed printing press, Oliver 266EPZ (manufactured by Sakurai Graphic Systems Co., Ltd.). The lithographic printing plates obtained in Example 3 and Comparative Examples 8 and 9 were mounted on this printing tester. While controlling the temperature of the ink roller using a chiller to change the surface temperature of the lithographic printing plate, offset printing was performed using UV ink UV171CT TW-M (manufactured by T&K TOKA Corporation) by the ink roller, in which the UV ink was supplied to the printing plate and transferred to thin coated paper via a blanket. The amount of UV ink supplied was adjusted so that the reflection density of the solid printed areas in the resulting print was 1.8 (black), and the coated paper to which the UV ink had been transferred was irradiated with ultraviolet light to obtain a print. The ultraviolet light irradiation was performed at an output of 120 W / cm. ２The irradiated area was a 100 mm wide lamp house in the flow direction, with a focal length of 150 mm, and the conveyor speed was 5 m / min. The printed matter was visually observed every 5,000 sheets to determine whether or not ink had adhered to non-image areas.

[0095] Example 1 A lithographic printing plate precursor PL-1 was exposed to a CTP exposure machine "PlateRite 8800E" (manufactured by SCREEN Holdings Co., Ltd.) using a laser beam with a wavelength of 830 nm and an irradiation energy of 100 mJ / cm. ２ The exposure was carried out under the conditions of (1) to (99%), and a latent image of 175 lpi at 2,400 dpi was formed in the center of a lithographic printing plate precursor measuring 550 mm length x 650 mm width. A lithographic printing plate was produced by passing the exposed lithographic printing plate precursor through an automatic developing machine "TWL-1160F" (manufactured by Toray Industries, Inc.) filled with pretreatment liquid PT-1 at a speed of 30 cm / min. The resulting lithographic printing plate was evaluated for (3) image reproducibility and (4) ink-repellent layer peeling resistance.

[0096] (Examples 2 to 14, Comparative Examples 1 to 9) Lithographic printing plates were produced in the same manner as in Example 1, except that the types of lithographic printing plate precursors and pretreatment liquids were changed as shown in Table 2. The resulting lithographic printing plates were evaluated for (3) image reproducibility and (4) ink-repellent layer peeling resistance. Furthermore, when Example 3 was evaluated for (5) ink-repellent layer peeling resistance during printing, no ink-repellent layer peeling was observed even after 100,000 sheets had been printed. Meanwhile, when Comparative Examples 8 and 9 were evaluated for (5) ink-repellent layer peeling resistance during printing, ink-repellent layer peeling was observed after 3,000 sheets had been printed in Comparative Example 8 and after 10,000 sheets had been printed in Comparative Example 9.

[0097] Table 2 shows the main components of each example and comparative example, as well as the evaluation results of image reproducibility and ink repellent layer peeling resistance.

[0098]

Claims

1. A method for producing a lithographic printing plate, comprising: an exposure step of irradiating a lithographic printing plate precursor having at least a photosensitive layer and an ink-repellent layer on a substrate with light to form a latent image; a pretreatment step of contacting the lithographic printing plate precursor on which the latent image has been formed with a pretreatment liquid; and a development step of removing the ink-repellent layer in the latent image area, wherein the pretreatment liquid contains an amine compound and water, and the water content is 2 to 30% by mass.

2. The method for producing a lithographic printing plate according to claim 1, wherein the pretreatment liquid has an amine value of 25 to 45 mg KOH / g.

3. The method for producing a lithographic printing plate according to claim 1 or 2, wherein the pretreatment liquid further contains a glycol compound and / or a glycol ether compound.

4. The method for producing a lithographic printing plate according to claim 1 or 2, wherein the photosensitive layer of the lithographic printing plate precursor contains a light-to-heat conversion substance.

5. The method for producing a lithographic printing plate according to claim 4, wherein the photosensitive layer of the lithographic printing plate precursor contains a compound having an active hydrogen group.

6. The method for producing a lithographic printing plate according to claim 5, wherein the compound having an active hydrogen group contains a triphenylmethane dye and / or a cellulose derivative.

7. A method for producing a printed matter, comprising the steps of depositing ink on the image area of ​​a lithographic printing plate obtained by the method of claim 1 or 2, and transferring the ink to a substrate directly or via a blanket.

8. A pretreatment liquid for lithographic printing plates, comprising an amine compound and water, the water content being 2 to 30% by mass.

9. The pretreatment liquid for lithographic printing plates according to claim 8, wherein the amine value of the pretreatment liquid is 25 to 45 mgKOH / g.

10. The pretreatment liquid for a lithographic printing plate according to claim 8 or 9, wherein the pretreatment liquid further contains a glycol compound and / or a glycol ether compound.

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