On-press development type lithographic printing plate original plate, and method for manufacturing printing plate

Abstract

To provide an on-press development type lithographic printing plate original plate which can suppress plate shift of a lithographic printing plate during printing by a lithographic printing plate, and a method for manufacturing a printing plate using the on-press development type lithographic printing plate original plate.SOLUTION: There are provided an on-press development type lithographic printing plate original plate which has an image recording layer on a support, wherein tensile strength of the support is 160 MPa or more, and a coefficient of static friction between the outermost layer surface opposite to a side having the image recording layer and metal SUS 316 is 0.50 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an on-press development type lithographic printing plate precursor and a method for preparing a printing plate. [Background technology]

[0002] Generally, a lithographic printing plate consists of an oleophilic image area that accepts ink during the printing process and a hydrophilic non-image area that accepts fountain solution. Lithographic printing utilizes the mutual repulsion of water and oil-based ink, with the oleophilic image area of ​​the lithographic printing plate acting as the ink-receptive area and the hydrophilic non-image area acting as the fountain solution-receptive area (ink-non-receptive area), creating a difference in ink adhesion on the surface of the lithographic printing plate, and after ink is applied only to the image area, the ink is transferred to the printing substrate, such as paper, to produce a print.

[0003] Currently, image exposure is performed using computer-to-plate (CTP) technology in the platemaking process for producing lithographic printing plates from lithographic printing plate precursors. This means that image exposure is performed by scanning exposure directly onto the lithographic printing plate precursor using a laser or laser diode, without using a lithographic film.

[0004]

[0003] Meanwhile, with growing concern about the global environment, environmental issues related to waste liquids associated with wet processes such as development processes have come to the fore in the production of lithographic printing plate precursors, and as a result, efforts are being made to simplify or eliminate development processes. As one of the simplified development processes, a method called "on-press development" has been proposed. On-press development is a method in which, after image exposure of a lithographic printing plate precursor, the plate is directly mounted on a printing press without undergoing conventional wet development processes, and the non-image areas of the image-recording layer are removed at an early stage of the normal printing process.

[0005] When printing using a lithographic printing plate, in newspaper printing, the lithographic printing plate is generally wound around a plate cylinder and printed continuously onto rolled paper using a rotary press.

[0006] Patent Document 1 describes a lithographic printing plate precursor characterized by comprising a support having a tensile strength of 180 MPa to 300 MPa, the support being an aluminum alloy plate that has been subjected to a surface roughening treatment, and a photosensitive layer containing an organic boron compound, a polymerization initiator, and a polymerizable compound provided on the support. Patent Document 2 describes a lithographic printing plate precursor having a water-soluble or water-dispersible negative-tone image recording layer on a hydrophilized aluminum support, in which the arithmetic mean height Sa of the outermost layer surface on the side opposite to the image recording layer is 0.3 μm or more and 20 μm or less, and in which a particulate-shaped polymer compound contained in the image recording layer has a hydrophobic main chain and includes both i) a constituent unit having a pendant cyano group directly bonded to the hydrophobic main chain, and ii) a constituent unit having a pendant group including a hydrophilic polyalkylene oxide segment. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-250104 [Patent Document 2] Patent No. 6454057 Summary of the Invention [Problem to be solved by the invention]

[0008] In newspaper printing, the lithographic printing plate wound around the plate cylinder can shift during printing (a phenomenon known as "plate misalignment"). For example, in multicolor printing, if plate misalignment occurs, the image set on the page will not overlap as intended, resulting in a shift in the position of the image, which may require the plate to be replaced and the print to be repeated, which can take a long time to complete. Even with the conventional techniques described in Patent Documents 1 and 2, for example, it has been difficult to prevent misregistration.

[0009] The problem to be solved by the present invention is to provide an on-press development type lithographic printing plate precursor that can suppress misregistration of the lithographic printing plate during printing with the lithographic printing plate, and a method for producing a printing plate using the on-press development type lithographic printing plate precursor. [Means for solving the problem]

[0010] The means for solving the above problems are described below.

[0011] [1] an image recording layer on a support, The support has a tensile strength of 160 MPa or more, An on-press development type lithographic printing plate precursor, wherein the static friction coefficient between the surface of the outermost layer on the side opposite to the side having the image recording layer and metal SUS316 is 0.50 or less.

[0012] [2] The on-press development type lithographic printing plate precursor according to [1], wherein the support is an aluminum support, and the aluminum support contains 0.020% by mass or more of magnesium. [3] The on-press development type lithographic printing plate precursor according to [1], wherein the support is an aluminum support, and the aluminum support is an aluminum plate that has been heat-treated at 250°C or higher in a rolling step and then cold-rolled at a reduction ratio of 80% or higher.

[0013] [4] an image recording layer on a support, The support has a tensile strength of 160 MPa or more, The on-press development type lithographic printing plate precursor has an arithmetic mean height Sa of the outermost layer surface on the side opposite to the side having the image recording layer of 0.3 μm or more and 20.0 μm or less.

[0014] [5] The on-press development type lithographic printing plate precursor according to [4], which has a backcoat layer on the side opposite to the side having the image recording layer. [6] the backcoat layer contains particles, The on-press development type lithographic printing plate precursor according to [5], wherein the average thickness T [μm] of the backcoat layer and the average particle diameter D [μm] of the particles satisfy the following formula (1): D > T...Formula (1) [7] The on-press development type lithographic printing plate precursor according to [5], wherein the backcoat layer has a thin film portion and a thick film portion.

[0015] [8] an image recording layer on a support, The support has a tensile strength of 160 MPa or more, The surface free energy of the outermost layer surface on the side opposite to the side having the image recording layer is 60 mJ / m 2 The on-press development type lithographic printing plate precursor is as follows.

[0016] [9] the support has an anodized coating, The on-press developable lithographic printing plate precursor according to any one of [1] to [8], wherein the micropores in the anodized film are composed of large-diameter pores extending from the surface of the anodized film to a depth of 10 nm to 1,000 nm and small-diameter pores that communicate with the bottoms of the large-diameter pores and extend from the communicating positions to a depth of 20 nm to 2,000 nm, the large-diameter pores having an average diameter of 15 nm to 100 nm at the surface of the anodized film and the small-diameter pores having an average diameter of less than 15 nm at the communicating positions.

[0017]

[10] the support has an anodized coating, The on-press developable lithographic printing plate precursor according to any one of [1] to [8], wherein the micropores in the anodized film are composed of small-diameter pores extending from the surface of the anodized film to a depth of 10 nm to 1,000 nm and large-diameter pores that communicate with the bottoms of the small-diameter pores and extend from the communicating positions to a depth of 20 nm to 2,000 nm, and the average diameter of the small-diameter pores at the surface of the anodized film is 35 nm or less, and the average diameter of the large-diameter pores is 40 to 300 nm or less.

[0018]

[11] the support has an anodized coating, The anodized film is formed by the following processes in the order from the surface of the anodized film to the depth direction: an upper layer having a thickness of 30 to 500 nm and having micropores with an average diameter of 20 to 100 nm; an intermediate layer having a thickness of 100 to 300 nm and having micropores with an average diameter that is 1 / 2 to 5 times the average diameter of the micropores in the upper micropore layer; and A lower layer with a thickness of 300 to 2000 nm and micropores with an average diameter of 15 nm or less The on-press development type lithographic printing plate precursor according to any one of [1] to [8],

[0019]

[12] The on-press development type lithographic printing plate precursor according to any one of [1] to

[11] , wherein the image recording layer contains an infrared absorber, a polymerization initiator, a polymerizable compound, and a polymer compound.

[13] The on-press development type lithographic printing plate precursor according to any one of [1] to

[12] , wherein the image recording layer contains a color former.

[14] The on-press development type lithographic printing plate precursor according to any one of [1] to

[13] , wherein the image recording layer is water-soluble or water-dispersible.

[0020]

[15] The on-press development type lithographic printing plate precursor according to any one of

[12] to

[14] , wherein the polymer compound is in the form of particles.

[16] the particulate polymer compound has a hydrophobic main chain, i) a building block having a pendant cyano group attached directly to the hydrophobic backbone; and ii) a constitutional unit having a pendant group containing a hydrophilic poly(alkylene oxide) segment; The on-press development type lithographic printing plate precursor according to

[15] , which comprises both of the above.

[17] The on-press developable lithographic printing plate precursor according to

[15] , wherein the particulate polymer compound is obtained by reacting a polyisocyanate compound, which is an adduct of a polyhydric phenol compound having two or more hydroxy groups in the molecule with isophorone diisocyanate, with a compound having active hydrogen.

[0021]

[18] The on-press development type lithographic printing plate precursor according to any one of [1] to

[17] , wherein the edge of the lithographic printing plate precursor has a sagging shape with a sagging amount X of 25 to 150 μm and a sagging width Y of 70 to 300 μm.

[19] The on-press development type lithographic printing plate precursor according to

[18] , wherein the lithographic printing plate precursor has an ink repellent agent on a part or all of two opposing side surfaces.

[20] The on-press development type lithographic printing plate precursor according to any one of [1] to

[19] , wherein the arithmetic mean height Sa of the outermost layer surface on the side having the image recording layer is 0.3 μm or more and 20.0 μm or less.

[0022] [twenty one] A method for preparing a printing plate, comprising: a step of imagewise exposing the on-press development type lithographic printing plate precursor according to any one of [1] to

[20] ; and a step of supplying at least one of printing ink and fountain solution on a printing press to remove unexposed areas of the image recording layer of the on-press development type lithographic printing plate precursor. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide an on-press development type lithographic printing plate precursor that can suppress misregistration of the lithographic printing plate during printing with the lithographic printing plate, and a method for producing a printing plate using the on-press development type lithographic printing plate precursor. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a graph showing an example of an alternating current waveform used in electrochemical graining treatment. [Figure 2] FIG. 1 is a side view showing an example of a radial cell in electrochemical graining treatment using alternating current. [Figure 3] FIG. 2 is a schematic diagram showing the cross-sectional shape of an edge portion of a planographic printing plate precursor. [Figure 4] FIG. 2 is a conceptual diagram illustrating an example of a cutting section of a slitter device. [Figure 5] FIG. 1 is a side view showing the concept of a brush graining process used in mechanical roughening treatment in the production of an aluminum support. [Figure 6] FIG. 2 is a schematic diagram of an anodizing treatment device used in anodizing treatment. [Figure 7] 10A to 10C are diagrams illustrating a method for applying an ink repellent agent. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following description of the components may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the description of groups (atomic groups) in this specification, when a notation does not specify whether the group is substituted or unsubstituted, it encompasses both unsubstituted and substituted groups. For example, the term "alkyl group" encompasses not only alkyl groups without a substituent (unsubstituted alkyl groups) but also alkyl groups with a substituent (substituted alkyl groups). In this specification, "(meth)acrylic" is a term used as a concept that includes both acrylic and methacrylic, and "(meth)acryloyl" is a term used as a concept that includes both acryloyl and methacryloyl. The term "step" in this specification includes not only an independent step, but also a step that cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved. In the present invention, a combination of two or more preferred embodiments is a more preferred embodiment. Unless otherwise specified, the mass average molecular weight (Mw) and number average molecular weight (Mn) in this specification are molecular weights determined by gel permeation chromatography (GPC) using columns of TSKgel GMHxL, TSKgel G4000HxL, or TSKgel G2000HxL (all trade names manufactured by Tosoh Corporation) in a solvent of THF (tetrahydrofuran) and detected by a differential refractometer, and converted using polystyrene as a standard substance. The present invention will be described in detail below.

[0026] [On-press development type lithographic printing plate original plate] A first on-press development type lithographic printing plate precursor according to the present invention (hereinafter, also simply referred to as the first lithographic printing plate precursor) has an image recording layer on a support, The support has a tensile strength of 160 MPa or more, The on-press development type lithographic printing plate precursor has a static friction coefficient of 0.50 or less between the surface of the outermost layer on the side opposite to the side having the image recording layer and metal SUS316. A second on-press development type lithographic printing plate precursor according to the present invention (hereinafter simply referred to as the second lithographic printing plate precursor) has an image recording layer on a support, The support has a tensile strength of 160 MPa or more, The on-press development type lithographic printing plate precursor has an arithmetic mean height Sa of the outermost layer surface on the side opposite to the side having the image recording layer of 0.3 μm or more and 20.0 μm or less. Furthermore, a third on-press development type lithographic printing plate precursor according to the present invention (hereinafter, also simply referred to as the third lithographic printing plate precursor) has an image recording layer on a support, The support has a tensile strength of 160 MPa or more, The surface free energy of the outermost layer surface on the side opposite to the side having the image recording layer is 60 mJ / m 2 The following is an on-press development type lithographic printing plate precursor.

[0027] According to the first to third on-press development type lithographic printing plate precursors of the present invention (hereinafter collectively referred to as on-press development type lithographic printing plate precursors, or simply lithographic printing plate precursors), by adopting the above-mentioned configuration, it is possible to suppress misregistration of the lithographic printing plate during printing with the lithographic printing plate. The reason for this is not clear, but is presumed to be as follows. When printing newspapers, offset rotary presses are generally used. To mount a plate on the plate cylinder of some offset rotary presses, both the top and bottom edges of the printing plate are bent into a predetermined shape using a plate bending machine, one end of the bent portion is hooked onto the jaws of the plate cylinder, and the other end is pulled by a plate clamping device to mount the plate on the surface of the plate cylinder. Specifically, the plate is wrapped around the support so that the side opposite the side bearing the image recording layer is in contact with the plate cylinder. In such printing presses, because the jaws are only hooked, the clamping force on the jaw side is insufficient, and when pressure is applied to the plate from the blanket during printing, the printing plate slips away from the jaws (hereinafter referred to as "plate misalignment"). It is necessary to maintain close contact between the lithographic printing plate and the plate cylinder, but as mentioned above, both ends of the lithographic printing plate are hooked and fixed into the jaws of the plate cylinder, and the inventors have found that friction between the lithographic printing plate and the jaws at the jaws can cause the position of the lithographic printing plate to shift slightly. After extensive research, the inventors focused on the characteristics of the support in the lithographic printing plate and the frictional force between the surface of the support in the lithographic printing plate opposite to the side having the image recording layer and the plate cylinder.

[0028] In the first on-press development type lithographic printing plate precursor of the present invention, the support has a tensile strength of 160 MPa or more, and the static friction coefficient between the outermost layer surface on the side opposite to the image recording layer and metal SUS316 is 0.50 or less. When the support has a specific tensile strength, plate misalignment caused by elongation of the support can be suppressed during newspaper printing. Furthermore, the static friction coefficient between the surface opposite the image recording layer and the SUS316 metal is 0.50 or less, so the friction force between the lithographic printing plate obtained from the lithographic printing plate precursor and the plate cylinder is not too large. Even if the position of the lithographic printing plate shifts at the edge of the clamping portion, it can be corrected and returned to its original position. Generally, increasing the friction between the two contacting parts can suppress misalignment. However, in the present invention, the inventors have discovered that, conversely, keeping the static friction coefficient below a specific value contributes to suppressing plate misalignment. Therefore, it is believed that it is possible to suppress misregistration of the lithographic printing plate during printing.

[0029] In the second on-press development type lithographic printing plate precursor of the present invention, the support has the above-mentioned tensile strength, and the arithmetic mean height Sa of the outermost layer surface on the side opposite to the side having the image recording layer is 0.3 μm or more and 20.0 μm or less. By setting the arithmetic mean height to a specific value, as in the first on-press development type lithographic printing plate precursor, it is thought that the friction force between the lithographic printing plate obtained from the lithographic printing plate precursor and the plate cylinder does not become too large, and as in the first lithographic printing plate precursor, it becomes possible to suppress misregistration of the lithographic printing plate during printing. In the third on-press development type lithographic printing plate precursor of the present invention, the support has the above-mentioned tensile strength, and the surface free energy of the outermost layer surface on the side opposite to the side having the image recording layer is 60 mJ / m 2 By keeping the surface free energy at or below a specific value, it is thought that, as in the case of the first on-press development type printing plate precursor, the frictional force between the lithographic printing plate obtained from the lithographic printing plate precursor and the plate cylinder does not become too large, and as in the case of the first lithographic printing plate precursor, it becomes possible to suppress misregistration of the lithographic printing plate during printing.

[0030] The on-press development type lithographic printing plate precursor according to the present invention will be described in detail below.

[0031] (First on-press development type lithographic printing plate precursor) First, the first lithographic printing plate precursor of the present invention will be described. In the first lithographic printing plate precursor of the invention, the support has a tensile strength of 160 MPa or more. The tensile strength is measured using an autograph AGC-H5KN (manufactured by Shimadzu Corporation) as a tensile strength measuring device, with a sample being a JIS metal material tensile test piece No. 5, at a tensile speed of 2 mm / min.

[0032] The tensile strength of the support is 160 MPa or more, preferably 170 MPa or more, and more preferably 190 MPa or more. The maximum tensile strength of the support is not particularly limited, but is usually 300 MPa or less, preferably 250 MPa or less, and more preferably 220 MPa or less. There are no particular limitations on how the tensile strength of the support can be made 160 MPa or more. For example, as described below, the support may contain a specific amount of magnesium, or the rolling reduction in the rolling process of the support may be set to a specific amount or more.

[0033] The support is preferably an aluminum support. The aluminum plate used for such an aluminum support is made of a dimensionally stable metal containing aluminum as the main component, i.e., aluminum or an aluminum alloy. It is preferably selected from a pure aluminum plate and an alloy containing aluminum as the main component and trace amounts of other elements.

[0034] The foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is 10% by mass or less. Pure aluminum plate is preferable, but since completely pure aluminum is difficult to produce due to smelting technology, an alloy containing a small amount of foreign elements is also acceptable. The aluminum plate used for the aluminum support does not have a specific composition, and conventionally known aluminum plates, such as JIS A 1050, JIS A 1100, JIS A 3103, and JIS A 3005, that meet the above tensile strength can be appropriately used.

[0035] The support is preferably an aluminum support containing 0.020% by mass or more of magnesium. By adjusting the magnesium content (content) of the aluminum support to 0.020% by mass or more, a support having a tensile strength of 160 MPa or more can be suitably obtained. The magnesium content in the support is preferably 0.020% by mass or more, more preferably 0.040% by mass or more, and even more preferably 0.060% by mass or more. The magnesium content in the support is not particularly limited, but is usually 0.200% by mass or less, preferably 0.150% by mass or less, and more preferably 0.100% by mass or less.

[0036] The magnesium content in the support was measured using a light emission analyzer (PDA-5500, manufactured by Shimadzu Corporation) as the measuring device.

[0037] Furthermore, it is preferable that the support is an aluminum support, and that the aluminum support is obtained by heat-treating an aluminum plate constituting the aluminum support at 250°C or higher in a rolling step and then cold-rolling the aluminum plate at a reduction ratio of 80% or higher, thereby making it possible to suitably obtain a support having a tensile strength of 160 MPa or higher. The tensile strength of the support (preferably an aluminum support) can be controlled by controlling the reduction in the cold rolling step after heat treatment. The reduction here is calculated by (h1-h2) / h1, where h1 and h2 are the thicknesses of the material before and after rolling, respectively, and represents the degree of reduction in rolling, and is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. In addition, the rolling reduction is usually preferably less than 99%, and more preferably 98% or less. The thickness of the support (preferably an aluminum plate) is preferably about 0.1 to 0.6 mm.

[0038] (anodic oxide film) The support preferably has an anodized film. The anodized film refers to an anodized film (preferably an anodized aluminum film) having extremely fine pores (also called micropores) formed on the surface of a support (preferably an aluminum plate) by anodizing treatment. The micropores extend from the surface of the anodized film opposite the support in the thickness direction (toward the support, in the depth direction). The average diameter (average opening diameter) of the micropores on the surface of the anodized film is preferably 7 nm to 150 nm, more preferably 10 nm to 100 nm, even more preferably 10 nm to 60 nm, particularly preferably 15 nm to 60 nm, and most preferably 18 nm to 40 nm, from the viewpoints of tone reproducibility, printing durability, and blanket smear resistance. The depth of the micropores is preferably 10 nm to 3,000 nm, more preferably 10 nm to 2,000 nm, and even more preferably 10 nm to 1,000 nm.

[0039] The shape of the micropores is usually a substantially straight tube (substantially cylindrical) in which the diameter of the micropores remains almost constant in the depth direction (thickness direction), but they may also be a cone shape in which the diameter decreases continuously in the depth direction (thickness direction), or a shape in which the diameter decreases discontinuously in the depth direction (thickness direction). Examples of micropores whose diameter discontinuously decreases in the depth direction (thickness direction) include micropores composed of a large-diameter pore portion extending in the depth direction from the surface of the anodized film and a small-diameter pore portion that communicates with the bottom of the large-diameter pore portion and extends in the depth direction from the communicating position.

[0040] Specifically, micropores composed of large-diameter pores extending 10 nm to 1,000 nm in the depth direction from the surface of the anodized film and small-diameter pores that communicate with the bottoms of the large-diameter pores and extend a further 20 to 2,000 nm in the depth direction from the communicating position are preferred. The large diameter hole portion and the small diameter hole portion will be described in detail below.

[0041] -Large diameter hole- The average diameter (average opening diameter) of the large diameter pores on the surface of the anodized film is preferably 7 nm to 150 nm, more preferably 10 nm to 100 nm, even more preferably 15 nm to 100 nm, particularly preferably 15 nm to 60 nm, and most preferably 18 nm to 40 nm, from the viewpoints of tone reproducibility, printing durability, and blanket smear resistance. The average diameter of the large pores is calculated by observing the surface of the anodized film using a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000 times (N=4 images), measuring the diameter of the micropores (large pores) present in an area of ​​400 nm x 600 nm in the four images obtained, and determining the arithmetic mean value of the diameters. If the shape of the large-diameter hole is not circular, the equivalent circle diameter is used. The "equivalent circle diameter" is the diameter of a circle when the shape of the opening is assumed to be a circle with the same projected area as the projected area of ​​the opening.

[0042] The bottoms of the large diameter holes are preferably located at a depth of 70 nm to 1,000 nm (hereinafter also referred to as depth A) from the surface of the anodized film. That is, the large diameter holes are preferably holes extending 70 nm to 1,000 nm in the depth direction (thickness direction) from the surface of the anodized film. In particular, the depth A is more preferably 90 nm to 850 nm, even more preferably 90 nm to 800 nm, and particularly preferably 90 nm to 600 nm, in terms of achieving a more excellent effect in the method for producing a lithographic printing plate precursor. The depth is calculated as the arithmetic mean value by taking a photograph (150,000 times) of the cross section of the anodized film, measuring the depths of 25 or more large diameter holes, and then calculating the depth.

[0043] The shape of the large-diameter hole is not particularly limited, and examples thereof include a substantially straight tube shape (a substantially cylindrical shape) and a cone shape whose diameter decreases in the depth direction (thickness direction), with a substantially straight tube shape being preferred. The shape of the bottom of the large-diameter hole is also not particularly limited, and may be curved (convex) or flat. The inner diameter of the large pores is not particularly limited, but is preferably about the same as or smaller than the diameter of the openings. The inner diameter of the large pores may differ from the diameter of the openings by about 1 nm to 10 nm.

[0044] -Small diameter hole- The small diameter hole is a hole that communicates with the bottom of the large diameter hole and extends further in the depth direction (thickness direction) from the communicating position. One small diameter hole usually communicates with one large diameter hole, but two or more small diameter holes may communicate with the bottom of one large diameter hole. The average diameter of the small diameter pores at the communicating positions is preferably smaller than 15 nm, more preferably 13 nm or less, even more preferably 11 nm or less, and particularly preferably 10 nm or less. There is no particular lower limit, but 5 nm is preferred.

[0045] The average diameter of the small pores is calculated by observing four images of the anodized film surface using an FE-SEM at 150,000x magnification, measuring the diameters of the micropores (small pores) present in an area of ​​400 nm x 600 nm in the four obtained images, and determining the arithmetic mean value of the diameters. If the large pores are deep, the upper part of the anodized film (the area where the large pores are located) may be cut (for example, with argon gas) as necessary, and then the surface of the anodized film may be observed using the FE-SEM to determine the average diameter of the small pores. If the shape of the small-diameter hole is not circular, the equivalent circle diameter is used. The "equivalent circle diameter" is the diameter of a circle when the shape of the opening is assumed to be a circle with the same projected area as the projected area of ​​the opening.

[0046] The bottoms of the small diameter pores are preferably located at positions extending 20 nm to 2,000 nm in the depth direction from the positions where the small diameter pores communicate with the large diameter pores (corresponding to the depth A described above). In other words, the small diameter pores are pores that extend further in the depth direction (thickness direction) from the positions where the small diameter pores communicate with the large diameter pores, and the depth of the small diameter pores is preferably 20 nm to 2,000 nm, more preferably 100 nm to 1,500 nm, and particularly preferably 200 nm to 1,000 nm. The depth is calculated as the arithmetic mean value by taking a photograph (150,000 times) of the cross section of the anodized film, measuring the depths of 25 or more small diameter holes, and then calculating the depth.

[0047] The shape of the small-diameter hole is not particularly limited, and examples thereof include a substantially straight tube shape (a substantially cylindrical shape) and a cone shape whose diameter decreases in the depth direction, with a substantially straight tube shape being preferred. The shape of the bottom of the small-diameter hole is not particularly limited, and may be a curved (convex) shape or a flat shape. The inner diameter of the small-diameter hole is not particularly limited, but may be approximately the same as the diameter at the communicating position, or may be smaller or larger than the diameter. Note that the inner diameter of the small-diameter hole may usually differ from the diameter of the opening by about 1 nm to 10 nm.

[0048] The ratio of the average diameter of the large pores on the surface of the anodized film to the average diameter of the small pores at their communicating positions, i.e., (average diameter of the large pores on the surface of the anodized film) / (average diameter of the small pores at their communicating positions), is preferably 1.1 to 13, and more preferably 2.5 to 6.5. The ratio of the depth of the large diameter hole portions to the depth of the small diameter hole portions, (depth of the large diameter hole portions) / (depth of the small diameter hole portions), is preferably 0.005-50, and more preferably 0.025-40.

[0049] The shape of the micropores is generally a substantially straight tube (cylindrical) shape in which the diameter of the micropores remains almost constant in the depth direction (thickness direction), but they may also be conical in which the diameter increases continuously in the depth direction (thickness direction), or may be a shape in which the diameter increases discontinuously in the depth direction (thickness direction). Examples of micropores whose diameter increases discontinuously in the depth direction (thickness direction) include micropores composed of a small-diameter pore portion extending in the depth direction from the surface of the anodized film and a large-diameter pore portion that communicates with the bottom of the small-diameter pore portion and extends in the depth direction from the communicating position.

[0050] Specifically, micropores composed of small-diameter pores extending 10 nm to 1,000 nm in the depth direction from the surface of the anodized film and large-diameter pores that communicate with the bottoms of the small-diameter pores and extend a further 20 to 2,000 nm in the depth direction from the communicating position are preferred.

[0051] -Small diameter hole- The average diameter (average opening diameter) of the small pores on the surface of the anodized film is not particularly limited, but is preferably 35 nm or less, more preferably 25 nm or less, and particularly preferably 20 nm or less. There is no particular lower limit, but 15 nm is preferred. The average diameter of the small pores is calculated by observing the surface of the anodized film using a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000 times (N=4 images), measuring the diameter of the micropores (large pores) present in an area of ​​400 nm x 600 nm in the four images obtained, and determining the arithmetic mean value of the diameters. If the shape of the small-diameter hole is not circular, the equivalent circle diameter is used. The "equivalent circle diameter" is the diameter of a circle when the shape of the opening is assumed to be a circle with the same projected area as the projected area of ​​the opening.

[0052] The bottoms of the small diameter pores are preferably located at a depth of 70 nm to 1,000 nm (hereinafter also referred to as depth A') from the surface of the anodized film. In other words, the small diameter pores are preferably pores that extend 70 nm to 1,000 nm in the depth direction (thickness direction) from the surface of the anodized film. The depth is calculated as the arithmetic mean value by taking a photograph (150,000 times) of the cross section of the anodized film, measuring the depths of 25 or more large diameter holes, and then calculating the depth.

[0053] The shape of the small diameter hole is not particularly limited, and examples thereof include a substantially straight tube shape (a substantially cylindrical shape) and a cone shape whose diameter increases in the depth direction (thickness direction), with a substantially straight tube shape being preferred. The shape of the bottom of the small diameter hole is also not particularly limited, and may be curved (convex) or flat. The inner diameter of the small-diameter hole is not particularly limited, but is preferably about the same as or smaller than the diameter of the opening. The inner diameter of the small-diameter hole may differ from the diameter of the opening by about 1 nm to 10 nm.

[0054] -Large diameter hole- The large diameter hole is a hole that communicates with the bottom of the small diameter hole and extends further in the depth direction (thickness direction) from the communicating position. Usually, one large diameter hole may have two or more small diameter holes that communicate with the bottom of one large diameter hole. The average diameter of the large diameter pores at the communicating positions is preferably 20 nm to 400 nm, more preferably 40 nm to 300 nm, further preferably 50 nm to 200 nm, and particularly preferably 50 nm to 100 nm.

[0055] The average diameter of the large pores is calculated by observing four images of the anodized film surface using an FE-SEM at 150,000x magnification, measuring the diameters of the micropores (large pores) present in an area of ​​400 nm x 600 nm in the four obtained images, and determining the arithmetic mean value of the diameters. If the small pores are deep, the upper part of the anodized film (the area where the small pores are located) may be cut (for example, with argon gas) as necessary, and then the surface of the anodized film may be observed using the FE-SEM to determine the average diameter of the large pores. If the shape of the large-diameter hole is not circular, the equivalent circle diameter is used. The "equivalent circle diameter" is the diameter of a circle when the shape of the opening is assumed to be a circle with the same projected area as the projected area of ​​the opening.

[0056] The bottoms of the large diameter pores are preferably located at positions extending 20 nm to 2,000 nm in the depth direction from the positions where the large diameter pores communicate with the small diameter pores (corresponding to the depth A' described above). In other words, the large diameter pores are pores that extend further in the depth direction (thickness direction) from the positions where the large diameter pores communicate with the small diameter pores, and the depth of the large diameter pores is preferably 20 nm to 2,000 nm, more preferably 100 nm to 1,500 nm, and particularly preferably 200 nm to 1,000 nm. The depth is calculated as the arithmetic mean value by taking a photograph (150,000 times) of the cross section of the anodized film, measuring the depths of 25 or more large diameter holes, and then calculating the depth.

[0057] The shape of the large-diameter hole is not particularly limited, and examples thereof include a substantially straight tube shape (a substantially cylindrical shape) and a cone shape whose diameter decreases in the depth direction, with a substantially straight tube shape being preferred. The shape of the bottom of the large-diameter hole is also not particularly limited, and may be a curved (convex) shape or a flat shape. The inner diameter of the large-diameter hole is not particularly limited, but may be approximately the same as the diameter at the communicating position, or may be smaller or larger than the diameter. Note that the inner diameter of the large-diameter hole may usually differ from the diameter of the opening by about 1 nm to 10 nm.

[0058] the support has an anodized coating, The anodized film is formed by the following processes in the order from the surface of the anodized film to the depth direction: an upper layer having a thickness of 30 to 500 nm and having micropores with an average diameter of 20 to 100 nm; an intermediate layer having a thickness of 100 to 300 nm and having micropores with an average diameter that is 1 / 2 to 5 times the average diameter of the micropores in the upper micropore layer; and A lower layer with a thickness of 300 to 2000 nm and micropores with an average diameter of 15 nm or less It is preferred that the compound has the following structure:

[0059] In an on-press development type lithographic printing plate precursor, it is useful for the anodized film surface of the support (the surface on which the image recording layer is formed) to have high brightness in order to improve image visibility. In the printing process of a lithographic printing plate, a plate inspection is usually carried out to confirm whether the intended image has been recorded before the printing plate is mounted on a printing press. In the case of an on-press development type lithographic printing plate precursor, it is required to check the image at the stage where the image has been image-exposed, so a means is applied which produces a so-called print-out image in the image-exposed area. One method for quantitatively evaluating the visibility of the image area (image visibility) of an image-exposed, on-press-developable lithographic printing plate precursor is to measure the lightness of the image-exposed area and the lightness of the unexposed area and determine the difference between them. Here, the lightness can be the lightness L* value in the CIEL*a*b* color system, and the measurement can be carried out using a colorimeter (SpectroEye, manufactured by X-Rite Corporation). The greater the difference between the lightness of the image-exposed area and the lightness of the unexposed area obtained by measurement, the easier the image area will be to view. It has been found that a high lightness L* value in the CIEL*a*b* color system of the anodized coating surface is effective in increasing the difference in lightness between the image-exposed and unexposed areas. That is, the lightness L* value is preferably 60 to 100.

[0060] The support having an anodized coating may, if necessary, have a backcoat layer containing an organic polymer compound described in JP-A-5-45885 or a silicon alkoxy compound described in JP-A-6-35174 on the side opposite to the side on which the constituent layer containing a hydroxy acid compound having two or more hydroxyl groups is formed.

[0061] (Production of an aluminum substrate having an anodized film) As an example of the support, a method for producing an aluminum support having an anodized film will be described. An aluminum support having an anodized film can be produced using a known method. The method for producing an aluminum support having an anodized film is not particularly limited. A preferred embodiment of the method for producing an aluminum support having an anodized film includes a step of roughening an aluminum plate (surface roughening step), a step of anodizing the surface-roughened aluminum plate (anodizing step), and a step of contacting the aluminum plate having the anodized film obtained in the anodizing step with an acid aqueous solution or an alkaline aqueous solution to enlarge the diameter of the micropores in the anodized film (pore widening step).

[0062] Each step will be described in detail below.

[0063] <Surface roughening process> The surface roughening step is a step of subjecting the surface of the aluminum plate to a surface roughening treatment, including electrochemical surface roughening. The surface roughening step is preferably performed before the anodizing treatment step described below, but may not be performed if the surface of the aluminum plate already has a desired surface shape.

[0064] The roughening treatment may be electrochemical roughening treatment alone, or may be a combination of electrochemical roughening treatment and at least one of mechanical roughening treatment and chemical roughening treatment. When mechanical graining treatment and electrochemical graining treatment are combined, it is preferable to carry out electrochemical graining treatment after mechanical graining treatment.

[0065] The electrochemical graining treatment is preferably carried out in an aqueous solution of nitric acid or hydrochloric acid.

[0066] Mechanical graining is generally carried out with the aim of making the surface of the aluminum plate have a surface roughness Ra of 0.35 to 1.0 μm. The conditions for the mechanical graining treatment are not particularly limited, but the treatment can be carried out, for example, according to the method described in Japanese Patent Publication No. 50-40047. The mechanical graining treatment can be carried out by brush graining using a pumice suspension or by a transfer method. The chemical roughening treatment is not particularly limited, and can be carried out according to a known method.

[0067] After the mechanical roughening treatment, it is preferable to carry out the following chemical etching treatment. The chemical etching treatment carried out after the mechanical graining treatment is carried out to smooth the uneven edges of the surface of the aluminum plate, prevent ink from catching during printing, improve the stain resistance of the lithographic printing plate, and remove any unwanted material such as abrasive particles remaining on the surface. Known chemical etching processes include acid etching and alkali etching, but a method that is particularly excellent in terms of etching efficiency is chemical etching using an alkaline solution (hereinafter also referred to as "alkali etching process").

[0068] The alkaline agent used in the alkaline solution is not particularly limited, but suitable examples include caustic soda, caustic potash, sodium metasilicate, sodium carbonate, sodium aluminate, and sodium gluconate. The alkaline solution may contain aluminum ions. The concentration of the alkaline agent in the alkaline solution is preferably 0.01% by mass or more, more preferably 3% by mass or more, and is preferably 30% by mass or less, more preferably 25% by mass or less. Furthermore, the temperature of the alkaline solution is preferably room temperature or higher, more preferably 30°C or higher, and is preferably 80°C or lower, more preferably 75°C or lower.

[0069] The etching amount is 0.01 g / m 2 More than 0.05 g / m is preferable. 2 More preferably, 30 g / m 2 Less than 20 g / m is preferred 2 The following is more preferred: The treatment time is preferably 2 seconds to 5 minutes depending on the etching amount, and more preferably 2 to 10 seconds from the viewpoint of improving productivity.

[0070] When alkaline etching treatment is performed after mechanical graining treatment, it is preferable to perform chemical etching treatment (hereinafter also referred to as "desmutting treatment") using a low-temperature acidic solution in order to remove products produced by the alkaline etching treatment. The acid used in the acidic solution is not particularly limited, but examples include sulfuric acid, nitric acid, and hydrochloric acid. The concentration of the acidic solution is preferably 1 to 50% by mass. The temperature of the acidic solution is preferably 20 to 80°C. When the concentration and temperature of the acidic solution are within these ranges, the resistance to dot-like staining in lithographic printing plates using aluminum supports is further improved.

[0071] A preferred embodiment of the surface roughening treatment step will be exemplified below. -Aspect SA- A mode in which the processes shown in (1) to (8) are carried out in this order. (1) Chemical etching treatment using an alkaline aqueous solution (first alkaline etching treatment) (2) Chemical etching treatment using an acidic aqueous solution (first desmutting treatment) (3) Electrochemical roughening treatment using an aqueous solution mainly containing nitric acid (first electrochemical roughening treatment) (4) Chemical etching treatment using an alkaline aqueous solution (second alkaline etching treatment) (5) Chemical etching treatment using an acidic aqueous solution (second desmutting treatment) (6) Electrochemical roughening treatment using an aqueous solution mainly containing hydrochloric acid (second electrochemical roughening treatment) (7) Chemical etching treatment using an alkaline aqueous solution (third alkaline etching treatment) (8) Chemical etching treatment using an acidic aqueous solution (third desmutting treatment)

[0072] -Aspect SB- A mode in which the processes shown in (11) to (15) are carried out in this order. (11) Chemical etching treatment using alkaline aqueous solution (fourth alkaline etching treatment) (12) Chemical etching treatment using an acidic aqueous solution (fourth desmutting treatment) (13) Electrochemical roughening treatment using an aqueous solution mainly containing hydrochloric acid (third electrochemical roughening treatment) (14) Chemical etching treatment using alkaline aqueous solution (fifth alkaline etching treatment) (15) Chemical etching treatment using an acidic aqueous solution (fifth desmutting treatment)

[0073] Before the treatment (1) of the above-mentioned embodiment SA or before the treatment (11) of the embodiment SB, a mechanical graining treatment may be carried out as necessary.

[0074] The amount of aluminum plate dissolved in the first and fourth alkaline etching treatments was 0.5 g / m 2 ~30g / m 2 is preferred, and 1.0 g / m 2 ~20g / m 2 is more preferred.

[0075] The aqueous solution mainly containing nitric acid used in the first electrochemical graining treatment in embodiment SA includes an aqueous solution used in electrochemical graining treatment using direct or alternating current, such as an aqueous solution obtained by adding aluminum nitrate, sodium nitrate, or ammonium nitrate to a 1 g / L to 100 g / L aqueous nitric acid solution. The aqueous solution containing hydrochloric acid as a main component used in the second electrochemical graining treatment in embodiment SA and the third electrochemical graining treatment in embodiment SB includes an aqueous solution used in electrochemical graining treatments using direct current or alternating current. For example, an aqueous solution obtained by adding 0 g / L to 30 g / L of sulfuric acid to a 1 g / L to 100 g / L aqueous hydrochloric acid solution may be used. This aqueous solution may further contain nitrate ions such as aluminum nitrate, sodium nitrate, or ammonium nitrate; or chloride ions such as aluminum chloride, sodium chloride, or ammonium chloride.

[0076] The AC power waveform for the electrochemical graining treatment can be a sine wave, square wave, trapezoidal wave, triangular wave, etc. The frequency is preferably 0.1 Hz to 250 Hz. FIG. 1 is a graph showing an example of an alternating current waveform used in electrochemical graining treatment. In FIG. 1, ta is the anode reaction time, tc is the cathode reaction time, tp is the time it takes for the current to reach its peak from 0, Ia is the current at the peak in the anode cycle, and Ic is the current at the peak in the cathode cycle. In the trapezoidal wave, the time it takes for the current to reach its peak from 0 is preferably 1 msec to 10 msec. The conditions for one cycle of AC used in the electrochemical graining treatment are preferably such that the ratio of the anode reaction time ta to the cathode reaction time tc of the aluminum plate, tc / ta, is 1 to 20, the ratio of the quantity of electricity Qc when the aluminum plate is an anode to the quantity of electricity Qa when the aluminum plate is an anode, Qc / Qa, is 0.3 to 20, and the anode reaction time ta is in the range of 5 msec to 1,000 msec. The current density is the peak value of the trapezoidal wave, and both the anode cycle side Ia and the cathode cycle side Ic of the current are 10 to 200 A / dm 2Ic / Ia is preferably 0.3 to 20. The total amount of electricity involved in the anodic reaction of the aluminum plate at the time when the electrochemical graining treatment is completed is 25 C / dm 2 ~1,000C / dm 2 is preferred.

[0077] The electrochemical graining treatment using alternating current can be performed using the apparatus shown in FIG. FIG. 2 is a side view showing an example of a radial cell used in electrochemical graining treatment using alternating current. In Fig. 2, 50 is a main electrolytic cell, 51 is an AC power source, 52 is a radial drum roller, 53a and 53b are main electrodes, 54 is an electrolyte supply port, 55 is an electrolyte, 56 is a slit, 57 is an electrolyte passage, 58 is an auxiliary anode, 60 is an auxiliary anode cell, and W is an aluminum plate. When two or more electrolytic cells are used, the electrolysis conditions may be the same or different. The aluminum sheet W is wound around a radial drum roller 52 immersed in a main electrolytic cell 50, and is electrolyzed by main electrodes 53a and 53b connected to an AC power source 51 during transportation. An electrolyte 55 is supplied from an electrolyte supply port 54 through a slit 56 to an electrolyte passage 57 between the radial drum roller 52 and the main electrodes 53a and 53b. The aluminum sheet W treated in the main electrolytic cell 50 is then electrolyzed in an auxiliary anode cell 60. In this auxiliary anode cell 60, an auxiliary anode 58 is disposed opposite the aluminum sheet W, and the electrolyte 55 is supplied so as to flow through the space between the auxiliary anode 58 and the aluminum sheet W.

[0078] The amount of aluminum plate dissolved in the second alkaline etching treatment is set to 1.0 g / m, which is convenient for producing a predetermined lithographic printing plate precursor. 2 ~20g / m 2 is preferred, and 2.0 g / m 2 ~10g / m 2 is more preferred.

[0079] The amount of dissolution of the aluminum plate in the third alkaline etching treatment and the fifth alkaline etching treatment is set to 0.01 g / m in order to facilitate the production of a predetermined lithographic printing plate precursor. 2~0.8g / m 2 is preferred, and 0.05 g / m 2 ~0.3g / m 2 is more preferred.

[0080] In the chemical etching treatments using acidic aqueous solutions (first to fifth desmutting treatments), an acidic aqueous solution containing phosphoric acid, nitric acid, sulfuric acid, chromic acid, hydrochloric acid, or a mixed acid containing two or more of these acids is preferably used. The concentration of the acid in the acidic aqueous solution is preferably 0.5% by mass to 60% by mass.

[0081] <Anodizing process> The anodizing step is a step of forming an aluminum oxide film on the surface of the aluminum plate by anodizing the aluminum plate that has been subjected to the surface roughening treatment. The anodizing treatment forms an aluminum anodized film having micropores on the surface of the aluminum plate. The anodizing treatment can be carried out according to a method conventionally known in this field by appropriately setting the manufacturing conditions in consideration of the desired shape of the micropores, etc.

[0082] In the anodizing treatment process, aqueous solutions of sulfuric acid, phosphoric acid, oxalic acid, etc. can be used as the electrolyte. In some cases, aqueous or non-aqueous solutions of chromic acid, sulfamic acid, benzenesulfonic acid, etc., or a combination of two or more of these, can also be used. When a direct or alternating current is applied to the aluminum plate in the electrolyte, an anodized film can be formed on the surface of the aluminum plate. The electrolyte may contain aluminum ions. The aluminum ion content is not particularly limited, but is preferably 1 to 10 g / L.

[0083] The conditions for anodizing treatment are appropriately set depending on the electrolyte used, but generally, the electrolyte concentration is 1 to 80 mass % (preferably 5 to 20 mass %), the solution temperature is 5 to 70°C (preferably 10 to 60°C), and the current density is 0.5 to 60 A / dm 2 (Preferably 5 to 50 A / dm 2), a voltage of 1 to 100 V (preferably 5 to 50 V), and an electrolysis time of 1 to 100 seconds (preferably 5 to 60 seconds) are suitable.

[0084] A preferred example of anodizing treatment is the method described in British Patent No. 1,412,768, in which anodizing is carried out in sulfuric acid at a high current density.

[0085] Anodizing treatment can be performed multiple times. One or more of the conditions, such as the type, concentration, temperature, current density, voltage, and electrolysis time of the electrolyte used, can be changed in each anodizing treatment. When anodizing treatment is performed twice, the first anodizing treatment is sometimes called the first anodizing treatment, and the second anodizing treatment is sometimes called the second anodizing treatment. By performing the first and second anodizing treatments, anodized films with different shapes can be formed, making it possible to provide a lithographic printing plate precursor with excellent printing performance. Furthermore, the pore widening treatment described below can be performed following the anodizing treatment, and then the anodizing treatment can be performed again. In this case, the first anodizing treatment, the pore widening treatment, and the second anodizing treatment are performed. By using the above-mentioned first anodizing treatment, pore widening treatment, and second anodizing treatment, it is possible to form micropores consisting of large-diameter pores extending in the depth direction from the surface of the anodized film and small-diameter pores that communicate with the bottoms of the large-diameter pores and extend in the depth direction from the communicating position.

[0086] <Porewide processing process> The pore widening treatment is a treatment (pore size enlargement treatment) for enlarging the diameter of the micropores present in the anodized film formed by the anodizing treatment step. This pore widening treatment enlarges the diameter of the micropores, resulting in the formation of an anodized film having micropores with a larger average diameter.

[0087] The pore widening treatment can be carried out by contacting the aluminum plate obtained by the above-mentioned anodizing treatment step with an acid aqueous solution or an alkaline aqueous solution. The contacting method is not particularly limited, and examples thereof include a dipping method and a spraying method. Among these, the dipping method is preferred.

[0088] When an alkaline aqueous solution is used in the pore-widening treatment step, it is preferable to use at least one alkaline aqueous solution selected from the group consisting of sodium hydroxide, potassium hydroxide, and lithium hydroxide. The concentration of the alkaline aqueous solution is preferably 0.1 to 5% by mass. The pH of the alkaline aqueous solution is adjusted to 11 to 13, and the aluminum sheet is suitably brought into contact with the alkaline aqueous solution for 1 to 300 seconds (preferably 1 to 50 seconds) at 10 to 70°C (preferably 20 to 50°C). In this case, the alkaline treatment solution may contain metal salts of polyvalent weak acids such as carbonates, borates, and phosphates.

[0089] When an aqueous acid solution is used in the pore widening treatment step, it is preferable to use an aqueous solution of an inorganic acid such as sulfuric acid, phosphoric acid, nitric acid, or hydrochloric acid, or a mixture thereof. The concentration of the aqueous acid solution is preferably 1 to 80% by mass, more preferably 5 to 50% by mass. The temperature of the aqueous acid solution is suitably 5 to 70°C (preferably 10 to 60°C), and the aluminum plate is brought into contact with the aqueous acid solution for 1 to 300 seconds (preferably 1 to 150 seconds). The alkaline or acidic aqueous solution may contain aluminum ions. The content of aluminum ions is not particularly limited, but is preferably 1 to 10 g / L.

[0090] The method for producing an aluminum support having an anodized coating may include a hydrophilization treatment step after the pore-widening treatment step. The hydrophilization treatment may be carried out by a known method such as those described in paragraphs 0109 to 0114 of JP-A No. 2005-254638.

[0091] The hydrophilization treatment is preferably carried out by immersing the substrate in an aqueous solution of an alkali metal silicate such as sodium silicate or potassium silicate, or by applying a hydrophilic vinyl polymer or a hydrophilic compound to form a hydrophilic undercoat layer.

[0092] The hydrophilization treatment with an aqueous solution of an alkali metal silicate such as sodium silicate or potassium silicate can be carried out according to the method and procedure described in US Pat. Nos. 2,714,066 and 3,181,461.

[0093] In the first lithographic printing plate precursor of the present invention, the static friction coefficient between the surface of the outermost layer on the side opposite to the side having the image recording layer and metal SUS316 is 0.50 or less. Here, the side opposite to the side having the image recording layer means the side opposite to the side having the image recording layer with respect to the support. The outermost layer surface on the side opposite to the side having the image recording layer is the surface of the backcoat layer if a backcoat layer is present on the opposite side, and is the surface of the support if no layer is present on the opposite side.

[0094] The static friction coefficient was measured according to the method described in JIS P8147. Specifically, using a static friction coefficient measuring instrument TYPE:10 manufactured by Shinto Scientific Co., Ltd., the static friction coefficient between the outermost layer surface on the side opposite the image recording layer and the metal SUS316 was measured three times, and the average value of these measurements was taken as the static friction coefficient. The measurement was carried out in a thermostatic chamber maintained at a temperature of 25°C and a humidity of 50%. The static friction coefficient is 0.50 or less, preferably 0.30 or less, and more preferably 0.20 or less. The static friction coefficient is usually greater than 0, and preferably 0.03 or greater.

[0095] In order to achieve the static friction coefficient of 0.50 or less, for example, the arithmetic mean height Sa of the outermost layer surface on the side opposite to the side having the image recording layer is set to 0.3 to 20.0 μm, and the surface free energy of the outermost layer surface on the side opposite to the side having the image recording layer is set to 60 mJ / m 2The following are preferred. The arithmetic mean height Sa of the outermost layer surface on the side opposite to the side having the image recording layer is set to 0.3 to 20.0 μm, and the surface free energy of the outermost layer surface on the side opposite to the side having the image recording layer is set to 60 mJ / m 2 The following will be explained below.

[0096] (Second lithographic printing plate precursor) The second lithographic printing plate precursor of the present invention will now be described. The support is the same as the support in the above-mentioned first on-press development type lithographic printing plate precursor. Here, as described above, the side opposite to the side having the image recording layer means the side opposite to the side having the image recording layer with respect to the support. The outermost layer surface on the side opposite to the side having the image recording layer is the surface of the backcoat layer if a backcoat layer is present on the opposite side, and is the surface of the support if no layer is present on the opposite side. For example, when forming protrusions as described below, the lithographic printing plate precursor may have the backcoat layer as the outermost layer and a plurality of protrusions containing a polymer compound on the outside of the backcoat layer, or the support as the outermost layer and a plurality of protrusions containing a polymer compound on the outside of the support.

[0097] The arithmetic mean height Sa of the outermost layer surface on the side opposite to the side having the image recording layer is 0.3 μm or more and 20.0 μm or less. From the viewpoint of preventing plate misregistration, the arithmetic mean height Sa of the outermost layer surface on the side opposite to the side having the image recording layer is preferably 0.3 to 20.0 μm, more preferably 0.3 to 10.0 μm, and even more preferably 0.3 to 3.0 μm. The lithographic printing plate precursor preferably has a backcoat layer on the side opposite to the side having the image recording layer.

[0098] The arithmetic mean height Sa of the outermost layer surface is measured according to the method described in ISO 25178. Specifically, using a Micromap MM3200-M100 manufactured by Ryoka Systems Co., Ltd., measurements are taken at three or more locations selected from the same sample, and the average value of these measurements is taken as the arithmetic mean height Sa. The measurement range is a 400 μm × 400 μm area randomly selected from the sample surface.

[0099] In order to achieve the requirement that the arithmetic mean height Sa of the outermost layer surface be 0.3 to 20.0 μm, it is preferable that the outermost layer be formed into a shape having projections and recesses. Specifically, for example, there are two embodiments: an embodiment in which the outermost layer contains particles having an average particle size of 0.5 to 20.0 μm (embodiment 1), and an embodiment in which the outermost layer has a plurality of protrusions containing a polymer compound as a main component (embodiment 2). Here, the main component refers to the component with the highest content (mass %). In the second embodiment, the outermost layer and the plurality of protrusions included on the outside of the outermost layer constitute a backcoat layer. The outside of the outermost layer means the outside of the outermost layer on the side opposite to the side having the image recording layer, with respect to the support.

[0100] In the first embodiment, the particles having an average particle size of 0.5 to 20.0 μm are not particularly limited, but are preferably at least one type of particles selected from organic resin particles and inorganic particles.

[0101] Preferred examples of organic resin particles include particles made of synthetic resins such as poly(meth)acrylic acid esters, polystyrene and derivatives thereof, polyamides, polyimides, polyolefins such as low-density polyethylene, high-density polyethylene, and polypropylene, polyurethanes, polyureas, and polyesters, and particles made of natural polymers such as chitin, chitosan, cellulose, crosslinked starch, and crosslinked cellulose. Among these, synthetic resin particles have advantages such as easy particle size control and easy control of desired surface properties by surface modification.

[0102] Regarding the method of manufacturing organic resin particles, for relatively hard resins such as polymethyl methacrylate (PMMA), it is possible to make fine particles by crushing, but the method of synthesizing particles by emulsion suspension polymerization is preferably adopted due to the ease and precision of particle size control. Methods for producing organic resin particles are described in detail in "Ultrafine particles and materials" edited by the Materials Science Society of Japan, published by Shokabo in 1993, and "Production and applications of fine particles and powders" edited by Haruma Kawaguchi, published by CMC Publishing in 2005.

[0103] The organic resin particles are also commercially available, and examples thereof include cross-linked acrylic resins MX-40T, MX-80H3wT, MX-150, MX-180TA, MX-300, MX-500, MX-1000, MX-1500H, MR-2HG, MR-7HG, MR-10HG, MR-3GSN, MR-5GSN, MR-7G, MR-10G, MR-5C, and MR-7GC manufactured by Soken Chemical & Engineering Co., Ltd., styryl resin-based SX-350H and SX-500H, and acrylic resins manufactured by Sekisui Plastics Co., Ltd. Examples of suitable resins include polyolefin resins MBX-5, MBX-8, MBX-12, MBX-15, MBX-20, MB20X-5, MB30X-5, MB30X-8, MB30X-20, SBX-6, SBX-8, SBX-12, and SBX-17 manufactured by Mitsui Chemicals, Inc., and Chemipearl W100, W200, W300, W308, W310, W400, W401, W405, W410, W500, WF640, W700, W800, W900, W950, and WP100.

[0104] Examples of inorganic particles include silica, alumina, zirconia, titania, carbon black, graphite, BaSO4, ZnS, MgCO3, CaCO3, ZnO, CaO, WS2, MoS2, MgO, SnO2, α-Fe2O3, α-FeOOH, SiC, CeO2, BN, SiN, MoC, BC, WC, titanium carbide, corundum, artificial diamond, garnet, silica, tribolith, diatomaceous earth, and dolomite.

[0105] The particles are preferably particles having a hydrophilic surface, and include organic resin particles having a hydrophilic surface and inorganic particles having a hydrophilic surface. The organic resin particles having a hydrophilic surface are preferably organic resin particles coated with at least one inorganic compound selected from the group consisting of silica, alumina, titania, and zirconia, and particularly preferably organic resin particles coated with silica. The organic resin constituting the organic resin particles having a hydrophilic surface is preferably at least one resin selected from the group consisting of polyacrylic resins, polyurethane resins, polystyrene resins, polyester resins, epoxy resins, phenolic resins, and melamine resins.

[0106] Below, organic resin particles having a hydrophilic surface will be described in detail using organic resin particles coated with silica (hereinafter also referred to as "silica-coated organic resin particles") as an example, but organic resin particles having a hydrophilic surface are not limited to this.

[0107] Silica-coated organic resin particles are particles made of an organic resin and surface-coated with silica. It is preferable that the organic resin particles constituting the core do not soften or become sticky due to moisture in the air or temperature. Examples of organic resins constituting the organic resin particles in the silica-coated organic resin particles include polyacrylic resins, polyurethane resins, polystyrene resins, polyester resins, epoxy resins, phenolic resins, and melamine resins.

[0108] Preferred examples of materials for forming a silica layer that coats the surface of the silica-coated organic resin particles include compounds having an alkoxysilyl group, such as condensates of alkoxysiloxane-based compounds, particularly siloxane-based materials, specifically silica particles such as silica sol, colloidal silica, and silica nanoparticles. The silica-coated organic resin particles may be configured such that silica particles are attached as a solid component to the surface of the organic resin particles, or such that a siloxane-based compound layer is formed on the surface of the organic resin particles by a condensation reaction of an alkoxysiloxane-based compound.

[0109] Silica does not necessarily have to cover the entire surface of the organic resin particles, but it is preferable that the surface be coated in an amount of at least 0.5% by mass or more relative to the total mass of the organic resin particles. That is, the presence of silica on at least a portion of the surface of the organic resin particles improves the affinity of the organic particle surface with the coexisting water-soluble polymer, such as polyvinyl alcohol (PVA), thereby preventing the particles from falling off even when subjected to external stress, and maintaining excellent scratch resistance and ease of peeling during lamination without interleaving paper. Therefore, the term "silica coating" also encompasses the presence of silica on at least a portion of the surface of the organic resin particles. The state of silica surface coating can be confirmed by morphological observation using a scanning electron microscope (SEM), etc. The amount of silica coating can be confirmed by detecting Si atoms using elemental analysis such as X-ray fluorescence analysis and calculating the amount of silica present there.

[0110] The method for producing silica-coated organic resin particles is not particularly limited, and may be a method in which silica particles or a silica precursor compound are made to coexist with a monomer component that is the raw material for the organic resin particles, and a silica surface coating layer is formed simultaneously with the formation of the organic resin particles, or a method in which, after forming organic resin particles, silica particles are physically attached to the surface and then fixed.

[0111] An example of a method for producing silica-coated organic resin particles is described below. First, silica and a raw resin (more specifically, a raw resin, such as a suspension-polymerizable monomer, a suspension-crosslinkable prepolymer, or a resin liquid, which constitutes the organic resin) are added to water containing a suspension stabilizer appropriately selected from water-soluble polymers such as polyvinyl alcohol, methyl cellulose, and polyacrylic acid, and inorganic suspending agents such as calcium phosphate and calcium carbonate, and then stirred and mixed to prepare a suspension in which the silica and raw resin are dispersed. A suspension having a desired particle size can be prepared by adjusting the type and concentration of the suspension stabilizer, the stirring speed, and other factors. Next, the suspension is heated to initiate a reaction, and the resin raw material is subjected to suspension polymerization or suspension crosslinking to produce resin particles. During this process, the coexisting silica is immobilized on the resin particles that harden through polymerization or crosslinking, particularly near the surface of the resin particles due to its physical properties. The suspension is then subjected to solid-liquid separation, the suspension stabilizer adhering to the particles is removed by washing, and the mixture is dried. Thus, approximately spherical silica-coated organic resin particles of the desired particle size are obtained, to which silica is immobilized.

[0112] In this way, silica-coated organic resin particles of the desired particle size can be obtained by controlling the conditions during suspension polymerization or suspension crosslinking, or silica-coated organic resin particles of the desired size can be obtained by producing silica-coated organic resin particles without strictly controlling them and then filtering them using a mesh filtration method or the like.

[0113] Regarding the amounts of raw materials added to the mixture when producing silica-coated organic particles by the above method, for example, when the total amount of raw material resin and silica is 100 parts by mass, a preferred embodiment is as follows: first, 0.1 to 20 parts by mass of a suspension stabilizer is added to 200 to 800 parts by mass of water as a dispersion medium, and the mixture of 100 parts by mass of raw material resin and silica is thoroughly dissolved or dispersed. Then, the mixture is charged with 100 parts by mass of raw material resin and silica, and the stirring speed is adjusted so that the dispersed particles have a predetermined particle size. After this particle size adjustment, the liquid temperature is raised to 30 to 90°C, and the mixture is allowed to react for 1 to 8 hours.

[0114] The above-mentioned method is one example of a method for producing silica-coated organic resin particles. For example, silica-coated organic resin particles obtained by methods described in detail in JP-A Nos. 2002-327036, 2002-173410, 2004-307837, and 2006-38246 can also be suitably used in the present invention.

[0115] Silica-coated organic resin particles are also commercially available. Specific examples of silica / melamine composite particles include Optobeads 2000M, Optobeads 3500M, Optobeads 6500M, Optobeads 10500M, Optobeads 3500S, and Optobeads 6500S, all manufactured by Nissan Chemical Industries, Ltd. Specific examples of silica / acrylic composite particles include Art Pearl G-200 Transparent, Art Pearl G-400 Transparent, Art Pearl G-800 Transparent, Art Pearl GR-400 Transparent, Art Pearl GR-600 Transparent, Art Pearl GR-800 Transparent, and Art Pearl J-7P, all manufactured by Negami Chemical Industries, Ltd. Examples of silica / urethane composite particles include Art Pearl C-400 transparent, C-800 transparent, P-800T, U-600T, U-800T, CF-600T, and CF800T manufactured by Negami Chemical Industrial Co., Ltd., and Dynamic Beads CN5070D and Danplacoat THU manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.

[0116] The organic resin particles have been described above using silica-coated organic resin particles as an example, but the same can be done with organic resin particles coated with alumina, titania, or zirconia by using alumina, titania, or zirconia instead of silica.

[0117] The shape of the particles is preferably a spherical shape, but may also be a tabular shape or a so-called spindle shape whose projected view is an ellipse.

[0118] In the first embodiment, the average particle size of the particles is preferably 0.5 to 10.0 μm, and more preferably 0.5 to 5.0 μm.

[0119] The average particle size of particles means the volume average particle size, and the volume average particle size is measured using a laser diffraction / scattering particle size distribution analyzer. Specifically, the measurement is performed using, for example, a particle size distribution analyzer "Microtrac MT-3300II" (manufactured by Nikkiso Co., Ltd.). For other particles, the average particle size is measured by the same method unless otherwise specified.

[0120] In the first embodiment, the in-plane density of particles having an average particle size of 0.5 to 20.0 μm is 10,000 particles / mm 2 The in-plane density is preferably 100 to 5000 particles / mm or less. 2 , and more preferably 100 to 3000 pieces / mm 2 is.

[0121] The in-plane density can be confirmed by observing the surface of the lithographic printing plate precursor with a scanning electron microscope (SEM). Specifically, the surface of the lithographic printing plate precursor is observed at five points with a scanning electron microscope (SEM) and the number of particles is counted. 2 The particle size can be calculated by converting the particle size into the number of particles per unit area and then calculating the average value.

[0122] The outermost layer on the side opposite to the side having the image recording layer preferably contains a binder in addition to particles having an average particle size of 0.5 to 20.0 μm. Examples of binders include novolak resins such as phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, and phenol / cresol (m-, p-, or m- / p-mixed) mixed formaldehyde resin, resol resin, pyrogallol, acetone resin, epoxy resin, saturated copolymer polyester resin, phenoxy resin, polyvinyl acetal resin, vinylidene chloride copolymer resin, polybutene, polybutadiene, polyamide, and unsaturated copolymer polyester. It is preferable that the resin contains at least one selected from the group consisting of ester resin, polyurethane, polyurea, polyimide, polysiloxane, polycarbonate, epoxy resin, chlorinated polyethylene, aldehyde condensation resin of alkylphenol, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylate, carboxyvinyl polymer, acrylic resin copolymer resin, hydroxycellulose, hydroxymethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, cellulose acetate, methylcellulose, and carboxymethylcellulose. A water-insoluble resin is preferable to prevent the risk of dissolution in the fountain solution during on-press development.

[0123] The binder preferably contains at least one selected from the group consisting of polyurethane, acrylic resin, polystyrene, and polyethylene. In addition, in the above-mentioned aspect 1, it is preferable that the particles and the binder each independently contain at least one selected from the group consisting of polyurethane, acrylic resin, polystyrene, and polyethylene.

[0124] The outermost layer on the side opposite to the side having the image recording layer may contain other components in addition to the particles and binder. Examples of other components include known additives such as surfactants.

[0125] As described above, the lithographic printing plate precursor preferably has a backcoat layer on the side opposite to the side having the image recording layer. The thickness of the outermost layer on the side opposite to the side having the image recording layer is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, and even more preferably 0.5 to 3 μm. The outermost layer in "thickness of the outermost layer" is the backcoat layer. Furthermore, the "thickness" in "thickness of the outermost layer" is an average thickness, which corresponds to the average thickness T described below. the backcoat layer contains particles, It is preferable that the average thickness T [μm] of the backcoat layer and the average particle diameter D [μm] of the particles satisfy the following formula (1): This corresponds to the above embodiment (1). D > T...Formula (1) The average thickness was determined by taking cross-sectional SEM images at a magnification of 10,000x at five randomly selected locations on the backcoat layer, and averaging the thicknesses of the backcoat layer read from the images.

[0126] Examples of the polymer compound constituting the plurality of protrusions containing the polymer compound as a main component in aspect 2 include novolak resins such as phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, and phenol / cresol (m-, p-, or m- / p-mixed) mixed formaldehyde resin, resol resin, pyrogallol acetone resin, epoxy resin, saturated copolymer polyester resin, phenoxy resin, polyvinyl acetal resin, vinylidene chloride copolymer resin, polybutene, and polybutadiene. At least one polymer compound selected from the group consisting of polyamide, unsaturated copolymer polyester resin, polyurethane, polyurea, polyimide, polysiloxane, polycarbonate, epoxy resin, chlorinated polyethylene, aldehyde condensation resin of alkylphenol, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylate, carboxyvinyl polymer, acrylic resin copolymer resin, hydroxycellulose, hydroxymethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, cellulose acetate, methylcellulose, and carboxymethylcellulose is preferred.

[0127] The backcoat layer preferably has a thin film portion and a thick film portion, and the thick film portion is preferably formed by the protrusions. The shape and height of the protrusions are not particularly limited, but it is preferable that the arithmetic mean height Sa is 0.3 to 20.0 μm. The protrusions can be formed by appropriately selecting a composition containing at least one selected from the group consisting of particles and polymeric compounds as the backcoat layer coating liquid, and applying the composition by at least one method selected from the group consisting of a bar coating method, an inkjet printing method, a gravure printing method, a screen printing method, a spray coating method, and a slot die coating method. The protrusions may be stripe-shaped, dot-shaped, or dashed-line-shaped, and the protrusions can be formed, for example, based on the method described in paragraphs

[0074] to

[0092] of International Publication No. 2017 / 170391. In this way, a backcoat layer having a thin film portion and a thick film portion can be formed.

[0128] Examples of the binder contained in the outermost layer in embodiment 2 include polymer compounds similar to the polymer compounds contained in the protrusions, and the same applies to preferred embodiments. In aspect 2, from the viewpoint of preventing detachment of the protrusions, it is preferable that the binder contained in the outermost layer and the polymer compound contained in the protrusions contain the same type of resin. Here, "the same type of resin" means that the resin type is the same, such as polyurethane, acrylic resin, polystyrene, or polyethylene, and it is not necessary that all of the structural units in the resin are the same.

[0129] (Third on-press development type lithographic printing plate precursor) The third lithographic printing plate precursor of the present invention will now be described. The support is the same as the support in the above-mentioned first on-press development type lithographic printing plate precursor. Here, as described above, the side opposite to the side having the image recording layer means the side opposite to the side having the image recording layer with respect to the support. The outermost layer surface on the side opposite to the side having the image recording layer is the surface of the backcoat layer if a backcoat layer is present on the opposite side, and is the surface of the support if no layer is present on the opposite side. The surface free energy of the outermost layer surface on the side opposite to the side having the image recording layer is 60 mJ / m 2 is

[0130] The surface free energy was calculated from the contact angles with pure water and iodomethane using the Owens-Wedent theory. Specifically, the contact angles with pure water and iodomethane on the surface opposite to the side having the image recording layer were measured, and γsv was calculated by solving the following linear equation with two unknowns: d and γsv h The sum of these was taken as the surface energy γs.

[0131]

number

[0132] γsv d : Surface free energy dispersion term of the measurement surface γsv h : Surface free energy hydrogen bond term of the measurement surface γLv d : Surface free energy dispersion term of the dropping liquid γLv h : Hydrogen bond term of the surface free energy of the dropping liquid θ: Contact angle 2 seconds after dropping γL=γLv d +γLv h

[0133] [Table 1]

[0134] To prevent misalignment, the surface free energy is set to 60 mJ / m 2less than 50 mJ / m 2 or less, more preferably 45 mJ / m 2 The following is the result. The surface free energy is usually 0 mJ / m 2 Greater than 5 mJ / m 2 More preferably, 40 mJ / m 2 That's all.

[0135] The third lithographic printing plate precursor is not particularly limited as long as the surface free energy is within the above range, but it is preferred to provide a backcoat layer on the side opposite to the side having the image recording layer. The backcoat layer preferably contains a binder. Examples of polymer resins that can be used as binders include novolak resins such as phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, and phenol / cresol (m-, p-, or m- / p-mixed) mixed formaldehyde resin, resol resin, pyrogallol, acetone resin, epoxy resin, saturated copolymer polyester resin, phenoxy resin, polyvinyl acetal resin, vinylidene chloride copolymer resin, polybutene, polybutadiene, polyamide, and unsaturated copolymer polyester resin.

[0042] In the case of a lithographic printing plate precursor to be used for on-press development, a water-insoluble resin is preferably used in order to prevent the risk of dissolution in the fountain solution during on-press development. From the viewpoint of preventing misregistration, the binder preferably contains at least one selected from the group consisting of polyurethane, acrylic resin, polystyrene, and polyethylene.

[0136] [On-press development type lithographic printing plate original plate] The on-press development type lithographic printing plate precursor (hereinafter also referred to as "lithographic printing plate precursor") according to the present invention will be described below. The lithographic printing plate precursor preferably has an image recording layer on an aluminum support having the above-mentioned anodized film. On-press development is a method in which, after image exposure, a lithographic printing plate precursor is mounted on a printing press as is without undergoing conventional wet development processing, and the non-image areas of the image recording layer are removed at an early stage of the normal printing process. A lithographic printing plate precursor that can be subjected to on-press development is an on-press development type lithographic printing plate precursor.

[0137] [Image Recording Layer] According to one preferred embodiment of the image recording layer in the lithographic printing plate precursor, the image recording layer contains an infrared absorber, a polymerization initiator, a polymerizable compound, and a polymer compound. The image recording layer preferably further contains a chain transfer agent. According to another preferred embodiment of the image recording layer, the image recording layer contains an infrared absorbing agent, heat-fusible particles, and a binder polymer.

[0138] (Infrared absorber) The infrared absorber has a function of being excited by infrared rays and transferring electrons and / or energy to a polymerization initiator or the like. It also has a function of converting the absorbed infrared rays into heat. The infrared absorber preferably has a maximum absorption in the wavelength range of 750 to 1,400 nm. Examples of the infrared absorber include dyes and pigments, and dyes are preferably used.

[0139] As the dye, commercially available dyes and known dyes described in literature such as "Dye Handbook" (edited by the Organic Synthetic Chemistry Association, published in 1970) can be used. Specific examples include azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, and metal thiolate complex dyes. Of the dyes, cyanine dyes, squarylium dyes, and pyrylium salts are preferred, cyanine dyes are more preferred, and indolenine cyanine dyes are particularly preferred.

[0140] Examples of the cyanine dye include those represented by the following formula (a).

[0141] [ka]

[0142] In formula (a), X 1 represents a hydrogen atom, a halogen atom, -N(R 9 )(R 10 ), -X 2 -L 1 or the group shown below, where R 9 and R 10 may be the same or different, and each independently represents an aromatic hydrocarbon group having 6 to 10 carbon atoms, an alkyl group having 1 to 8 carbon atoms, or a hydrogen atom, or R 9 and R 10 may be bonded to each other to form a ring. The aromatic hydrocarbon group having 6 to 10 carbon atoms or the alkyl group having 1 to 8 carbon atoms may have a substituent. R 9 and R 10 Preferably, both X are phenyl groups. 2 represents an oxygen atom or a sulfur atom, L 1 represents a hydrocarbon group having 1 to 12 carbon atoms or a hydrocarbon group having 1 to 12 carbon atoms and containing a hetero atom. Here, the hetero atom represents N, S, O, a halogen atom, or Se. In the groups shown below, Xa - is Za -and Ra represents a hydrogen atom or a substituent selected from an alkyl group, an aryl group, a substituted or unsubstituted amino group, and a halogen atom.

[0143] [ka]

[0144] In formula (a), R 1 and R 2 each independently represents a hydrocarbon group having 1 to 12 carbon atoms. In view of the storage stability of the coating solution for the image recording layer, R 1 and R 2 is preferably a hydrocarbon group having two or more carbon atoms, and R 1 and R 2 are particularly preferably bonded to each other to form a 5-membered or 6-membered ring.

[0145] In formula (a), Ar 1 and Ar 2 may be the same or different and each represents an aromatic hydrocarbon group. The aromatic hydrocarbon group may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring group and a naphthalene ring group. Preferred substituents include a hydrocarbon group having 12 or less carbon atoms, a halogen atom, and an alkoxy group having 12 or less carbon atoms. Y 1 and Y 2 may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. 3 and R 4 may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms. The hydrocarbon group having 20 or less carbon atoms may have a substituent. Preferred substituents include an alkoxy group, a carboxy group, and a sulfo group having 12 or less carbon atoms. R 5 , R 6 , R 7 and R 8 may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. In view of the availability of raw materials, a hydrogen atom is preferred. -represents a counter anion. However, when the cyanine dye represented by formula (a) has an anionic substituent in its structure and charge neutralization is not required, Za - is not necessary. - In view of the storage stability of the image recording layer coating solution, the cation is preferably a halide ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, or a sulfonate ion, and more preferably a perchlorate ion, a hexafluorophosphate ion, or an arylsulfonate ion.

[0146] In the cyanine dye represented by formula (a), X 1 It is more preferable that X is a diphenylamino group. 1 is a diphenylamino group, and Y 1 and Y 2 It is more preferable that both of are dimethylmethylene groups.

[0147] Specific examples of cyanine dyes include the compounds described in paragraphs 0017 to 0019 of JP-A No. 2001-133969, the compounds described in paragraphs 0016 to 0021 of JP-A No. 2002-023360, and the compounds described in paragraphs 0012 to 0037 of JP-A No. 2002-040638, preferably the compounds described in paragraphs 0034 to 0041 of JP-A No. 2002-278057, and paragraphs 0080 to 0086 of JP-A No. 2008-195018, and particularly preferably the compounds described in paragraphs 0035 to 0043 of JP-A No. 2007-90850. In addition, the compounds described in paragraphs 0008 to 0009 of JP-A No. 5-5005 and paragraphs 0022 to 0025 of JP-A No. 2001-222101 can also be preferably used. As the pigment, the compounds described in paragraphs 0072 to 0076 of JP-A No. 2008-195018 are preferred.

[0148] The infrared absorbing agent may be used alone or in combination of two or more kinds. The content of the infrared absorbing agent is preferably from 0.05 to 30% by mass, more preferably from 0.1 to 20% by mass, and even more preferably from 0.2 to 10% by mass, based on the total solid content of the image recording layer.

[0149] (Polymerization initiator) The polymerization initiator is a compound that generates polymerization initiating species such as radicals or cations by the energy of light, heat, or both, and can be appropriately selected from known thermal polymerization initiators, compounds having a bond with small bond dissociation energy, photopolymerization initiators, etc. The polymerization initiator is preferably an infrared-sensitive polymerization initiator. Furthermore, the polymerization initiator is preferably a radical polymerization initiator. Two or more radical polymerization initiators may be used in combination.

[0150] The radical polymerization initiator may be either an electron-accepting polymerization initiator or an electron-donating polymerization initiator. As the electron-accepting polymerization initiator and the electron-donating polymerization initiator, those described in

[0085] to

[0103] of WO 2020 / 137919 can be used.

[0151] The electron-accepting polymerization initiator may be used alone or in combination of two or more kinds. The content of the electron-accepting polymerization initiator is preferably from 0.1 to 50% by mass, more preferably from 0.5 to 30% by mass, and even more preferably from 0.8 to 20% by mass, based on the total solid content of the image recording layer.

[0152] The electron-donating polymerization initiator may be used alone or in combination of two or more kinds. The content of the electron-donating polymerization initiator is preferably from 0.01 to 30% by mass, more preferably from 0.05 to 25% by mass, and even more preferably from 0.1 to 20% by mass, based on the total solid content of the image recording layer.

[0153] (polymerizable compound) The polymerizable compound may be, for example, a radically polymerizable compound or a cationically polymerizable compound, but is preferably an addition-polymerizable compound (ethylenically unsaturated compound) having at least one ethylenically unsaturated bond. As the ethylenically unsaturated compound, a compound having at least one terminal ethylenically unsaturated bond is preferred, and a compound having two or more terminal ethylenically unsaturated bonds is more preferred. The polymerizable compound can have a chemical form such as a monomer, a prepolymer, i.e., a dimer, a trimer, or an oligomer, or a mixture thereof.

[0154] Examples of monomers include unsaturated carboxylic acids (e.g., acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid), as well as their esters and amides. Esters of unsaturated carboxylic acids and polyhydric alcohol compounds and amides of unsaturated carboxylic acids and polyamine compounds are preferred. Also suitable are addition reaction products of unsaturated carboxylic acid esters or amides having a nucleophilic substituent, such as a hydroxy group, an amino group, or a mercapto group, with monofunctional or polyfunctional isocyanates or epoxies, and dehydration condensation reaction products of monofunctional or polyfunctional carboxylic acids. Also suitable are addition reaction products of unsaturated carboxylic acid esters or amides having an electrophilic substituent, such as an isocyanate group or an epoxy group, with monofunctional or polyfunctional alcohols, amines, or thiols, and substitution reaction products of unsaturated carboxylic acid esters or amides having a leaving substituent, such as a halogen atom or a tosyloxy group, with monofunctional or polyfunctional alcohols, amines, or thiols. As another example, compounds in which the above unsaturated carboxylic acids are replaced with unsaturated phosphonic acids, styrene, vinyl ethers, etc. can also be used. These compounds are described in JP-T-2006-508380, JP-A-2002-287344, JP-A-2008-256850, JP-A-2001-342222, JP-A-9-179296, JP-A-9-179297, JP-A-9-179298, JP-A-2004-294935, JP-A-2006-243493, JP-A-2002-275129, JP-A-2003-64130, JP-A-2003-280187, JP-A-10-333321, and the like.

[0155] Specific examples of ester monomers of polyhydric alcohol compounds and unsaturated carboxylic acids include acrylic esters such as ethylene glycol diacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, trimethylolpropane triacrylate, hexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol tetraacrylate, sorbitol triacrylate, ethylene oxide isocyanurate (EO)-modified triacrylate, and polyester acrylate oligomers. Specific examples of methacrylic esters include tetramethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, pentaerythritol trimethacrylate, bis[p-(3-methacryloxy-2-hydroxypropoxy)phenyl]dimethylmethane, and bis[p-(methacryloxyethoxy)phenyl]dimethylmethane. Specific examples of amide monomers of polyamine compounds and unsaturated carboxylic acids include methylenebisacrylamide, methylenebismethacrylamide, 1,6-hexamethylenebisacrylamide, 1,6-hexamethylenebismethacrylamide, diethylenetriaminetrisacrylamide, xylylenebisacrylamide, and xylylenebismethacrylamide.

[0156] Also suitable are urethane-based addition-polymerizable compounds produced by an addition reaction between an isocyanate and a hydroxy group. Specific examples thereof include vinyl urethane compounds containing two or more polymerizable vinyl groups in one molecule, as described in Japanese Patent Publication No. 48-41708, which are obtained by adding a vinyl monomer containing a hydroxy group represented by the following formula (M) to a polyisocyanate compound having two or more isocyanate groups in one molecule: CH2=C(R M4 )COOCH2CH(R M5 )OH (M) In formula (M), R M4 and R M5each independently represents a hydrogen atom or a methyl group.

[0157] Further, urethane acrylates described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-A-2003-344997, JP-A-2006-65210, JP-B-58-49860, JP-B-56-17654, JP-B-62-39417, JP-B-62-39418 Also suitable are urethane compounds having an ethylene oxide skeleton described in JP-A Nos. 2000-250211 and 2007-94138, and urethane compounds having a hydrophilic group described in U.S. Pat. No. 7,153,632, JP-A No. 8-505958, JP-A Nos. 2007-293221 and 2007-293223.

[0158] Details of the method of use, such as the structure of the polymerizable compound, whether it is used alone or in combination, and the amount added, can be determined as desired, taking into consideration the final use of the lithographic printing plate precursor. The content of the polymerizable compound is preferably from 1 to 50% by mass, more preferably from 3 to 30% by mass, and even more preferably from 5 to 20% by mass, based on the total solid content of the image recording layer.

[0159] (polymer compound) The polymer compound may function as a binder polymer in the image recording layer, or may be present in the image recording layer as a particulate polymer compound (polymer particles).

[0160] <Binder polymer> The binder polymer is preferably a polymer having film properties, and preferred examples thereof include (meth)acrylic resin, polyvinyl acetal resin, and polyurethane resin.

[0161] The binder polymer used in the image recording layer is preferably a binder polymer having an alkylene oxide chain. The binder polymer having an alkylene oxide chain may have a poly(alkylene oxide) moiety in the main chain or in a side chain. Alternatively, the binder polymer may be a graft polymer having a poly(alkylene oxide) moiety in the side chain, or a block copolymer of a block composed of a repeating unit containing a poly(alkylene oxide) moiety and a block composed of a repeating unit not containing an (alkylene oxide) moiety. When the main chain has a poly(alkylene oxide) moiety, polyurethane resin is preferred. When the side chain has a poly(alkylene oxide) moiety, examples of the main chain polymer include (meth)acrylic resin, polyvinyl acetal resin, polyurethane resin, polyurea resin, polyimide resin, polyamide resin, epoxy resin, polystyrene resin, novolac phenolic resin, polyester resin, synthetic rubber, and natural rubber, with (meth)acrylic resin being particularly preferred.

[0162] The alkylene oxide is preferably an alkylene oxide having 2 to 6 carbon atoms, and ethylene oxide or propylene oxide is particularly preferred. The number of repeating alkylene oxides in the poly(alkylene oxide) moiety is preferably 2-120, more preferably 2-70, and even more preferably 2-50. If the number of alkylene oxide repeats is 120 or less, the decrease in printing durability due to abrasion and the decrease in printing durability due to deterioration in ink receptivity are suppressed, which is preferable.

[0163] The poly(alkylene oxide) moiety is preferably contained as a side chain of the binder polymer in the form of a structure represented by the following formula (AO), and more preferably contained as a side chain of the (meth)acrylic resin in the form of a structure represented by the following formula (AO).

[0164] [ka]

[0165] In formula (AO), y represents 2 to 120, R1 represents a hydrogen atom or an alkyl group, and R2 represents a hydrogen atom or a monovalent organic group. The monovalent organic group is preferably an alkyl group having 1 to 6 carbon atoms, specifically, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an isohexyl group, a 1,1-dimethylbutyl group, a 2,2-dimethylbutyl group, a cyclopentyl group, and a cyclohexyl group. In formula (AO), y is preferably 2 to 70, more preferably 2 to 50. R1 is preferably a hydrogen atom or a methyl group, particularly preferably a hydrogen atom. R2 is particularly preferably a hydrogen atom or a methyl group.

[0166] The binder polymer may have crosslinking properties to improve the film strength of the image area. To impart crosslinking properties to the polymer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization or by a polymer reaction. Examples of polymers having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene. Examples of polymers having an ethylenically unsaturated bond in a side chain of the molecule include polymers of esters or amides of acrylic acid or methacrylic acid, in which the R of the ester or amide residue (-COOR or -CONHR) has an ethylenically unsaturated bond.

[0167] Examples of the residue having an ethylenically unsaturated bond (R) include -(CH2) n CR 1A =CR 2A R 3A , -(CHO) n CH2CR 1A =CR 2A R 3A , -(CH2CH2O) n CH2CR 1A=CR 2A R 3A , -(CH2) n NH-CO-O-CH2CR 1A =CR 2A R 3A , -(CH2) n -O-CO-CR 1A =CR 2A R 3A and -(CH2CH2O)2-X A (In the formula, R A1 ~R A3 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an alkoxy group, or an aryloxy group; R A1 and R A2 or R A3 may be bonded to each other to form a ring. n represents an integer of 1 to 10. X A represents a dicyclopentadienyl residue.

[0168] Specific examples of ester residues include -CH2CH=CH2, -CH2CHO-CH2CH=CH2, -CH2C(CH3)=CH2, -CH2CH=CH-CH6H5, -CH2CHOCOCH=CH-CH6H5, -CH2CH2-NHCOO-CH2CH=CH2 and -CH2CHO-X (wherein X represents a dicyclopentadienyl residue). Specific examples of amide residues include -CH2CH=CH2, -CH2CH2-Y (wherein Y represents a cyclohexene residue), and -CH2CH2-OCO-CH=CH2.

[0169] A crosslinkable binder polymer is cured by, for example, addition of a free radical (a polymerization initiation radical or a propagating radical in the polymerization process of a polymerizable compound) to its crosslinkable functional group, which then undergoes addition polymerization between polymers directly or via the polymerization chain of the polymerizable compound, forming a crosslink between polymer molecules. Alternatively, an atom in the polymer (e.g., a hydrogen atom on a carbon atom adjacent to a functional crosslinking group) is abstracted by the free radical to generate a polymer radical, which then bonds to each other, forming a crosslink between polymer molecules and curing.

[0170] The content of crosslinkable groups in the binder polymer (content of radically polymerizable unsaturated double bonds determined by iodometric titration) is preferably 0.1 to 10.0 mmol, more preferably 1.0 to 7.0 mmol, and even more preferably 2.0 to 5.5 mmol per gram of binder polymer, from the viewpoints of good sensitivity and good storage stability.

[0171] Specific examples 1 to 11 of binder polymers are shown below, but the present invention is not limited to these. In the following example compounds, the numerical value written next to each repeating unit (the numerical value written next to the main chain repeating unit) indicates the mole percentage of the repeating unit. The numerical value written next to the repeating unit of the side chain indicates the number of repeats of the repeating portion. Furthermore, Me represents a methyl group, Et represents an ethyl group, and Ph represents a phenyl group.

[0172] [ka]

[0173] [ka]

[0174] The molecular weight of the binder polymer is, in terms of polystyrene equivalent, a mass average molecular weight (Mw) measured by GPC method of 2,000 or more, preferably 5,000 or more, and more preferably 10,000 to 300,000.

[0175] If necessary, a hydrophilic polymer such as polyacrylic acid or polyvinyl alcohol described in JP-A-2008-195018 can be used in combination. Also, a lipophilic polymer and a hydrophilic polymer can be used in combination.

[0176] The binder polymer may be used alone or in combination of two or more kinds. The content of the binder polymer is preferably from 1 to 90% by mass, more preferably from 5 to 80% by mass, of the total solid content of the image recording layer.

[0177] <Particulate polymer compounds (polymer particles)> The image recording layer preferably contains polymer particles. The polymer particles contribute to improving on-press developability. The polymer particles are preferably polymer particles that can convert the image recording layer to a hydrophobic state when heat is applied. The polymer particles are preferably at least one selected from hydrophobic thermoplastic polymer particles, heat-reactive polymer particles, polymer particles having a polymerizable group, microcapsules encapsulating a hydrophobic compound, and microgels (crosslinked polymer particles).

[0178] Suitable examples of the hydrophobic thermoplastic polymer particles include those described in Research Disclosure No. 33303 published in January 1992, JP-A Nos. 9-123387, 9-131850, 9-171249, and 9-171250, and European Patent No. 931647. Specific examples of polymers constituting the hydrophobic thermoplastic polymer particles include homopolymers or copolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinylcarbazole, and acrylates or methacrylates having a polyalkylene structure, or mixtures thereof. Preferred examples include polystyrene, copolymers containing styrene and acrylonitrile, and polymethyl methacrylate. The average particle size of the hydrophobic thermoplastic polymer particles is preferably 0.01 to 2.0 μm.

[0179] The thermally reactive polymer particles include polymer particles having a thermally reactive group, which form a hydrophobic region by crosslinking through a thermal reaction and by changing the functional group.

[0180] As the thermally reactive group in the polymer particles having a thermally reactive group, as long as it can form a chemical bond, any functional group that undergoes any reaction can be used, and polymerizable group is preferred.Its example can suitably be mentioned the ethylenically unsaturated group (such as acryloyl group, methacryloyl group, vinyl group, allyl group, etc.) that undergoes radical polymerization reaction, cationic polymerizable group (such as vinyl group, vinyloxy group, epoxy group, oxetanyl group, etc.), the isocyanato group or its block compound that undergoes addition reaction, epoxy group, vinyloxy group and the functional group that has active hydrogen atom that is their reactive partner (such as amino group, hydroxy group, carboxy group, etc.), the carboxy group that undergoes condensation reaction and the hydroxy group or amino group that is their reactive partner, the acid anhydride that undergoes ring-opening addition reaction and the amino group or hydroxy group that is their reactive partner, etc.

[0181] Examples of microcapsules include those in which all or part of the components of the image recording layer are encapsulated in microcapsules, as described in JP-A Nos. 2001-277740 and 2001-277742. The components of the image recording layer can also be contained outside the microcapsules. In a preferred embodiment of the image recording layer containing microcapsules, hydrophobic components are encapsulated in the microcapsules and hydrophilic components are contained outside the microcapsules.

[0182] The microgel (crosslinked polymer particle) can contain a part of the constituent components of the image recording layer in at least one of its interior and surface. In particular, an embodiment in which the microgel has a radical polymerizable group on its surface to form a reactive microgel is preferred from the viewpoint of image formation sensitivity and printing durability.

[0183] Known methods can be used to microencapsulate or microgel the components of the image recording layer. The average particle size of the microcapsules or microgels is preferably 0.01 to 3.0 μm, more preferably 0.05 to 2.0 μm, and particularly preferably 0.10 to 1.0 μm. Good resolution and stability over time can be obtained within this range.

[0184] The polymer particles may be used alone or in combination of two or more kinds. The content of the polymer particles is preferably from 5 to 90% by mass, more preferably from 5 to 80% by mass, and even more preferably from 10 to 75% by mass, of the total solid content of the image recording layer.

[0185] In a preferred embodiment, the particle-shaped polymer compound has a hydrophobic main chain, i) a constitutional unit having a pendant cyano group attached directly to the hydrophobic backbone; and ii) a constitutional unit having a pendant group containing a hydrophilic poly(alkylene oxide) segment, and The hydrophobic main chain is preferably an acrylic resin chain. Preferred examples of the pendant cyano group include -[CH2CH(C≡N)-] or -[CH2C(CH3)(C≡N)-]. Furthermore, the structural unit having the pendant cyano group can be easily derived from an ethylenically unsaturated monomer, such as acrylonitrile or methacrylonitrile, or a combination thereof. The alkylene oxide in the hydrophilic poly(alkylene oxide) segment is preferably ethylene oxide or propylene oxide, more preferably ethylene oxide. The number of repeating alkylene oxide structures in the hydrophilic poly(alkylene oxide) segment is preferably 10-100, more preferably 25-75, and even more preferably 40-50. Preferred examples of resin particles having a hydrophobic main chain and including both i) a constituent unit having a pendant cyano group directly bonded to the hydrophobic main chain, and ii) a constituent unit having a pendant group containing a hydrophilic poly(alkylene oxide) segment include those described in paragraphs 0039 to 0068 of JP-A No. 2008-503365.

[0186] In one preferred embodiment, the particulate polymer compound is obtained by reacting a polyisocyanate compound, which is an adduct of a polyphenol compound having two or more hydroxy groups in the molecule with isophorone diisocyanate, with a compound having active hydrogen.

[0187] The average particle size of the polymer particles is preferably from 0.01 to 3.0 μm, more preferably from 0.05 to 2.0 μm, and particularly preferably from 0.10 to 1.0 μm. Good resolution and stability over time can be obtained within this range.

[0188] The polymer particles may be used alone or in combination of two or more kinds. The content of the polymer particles is preferably from 5 to 90% by mass, more preferably from 5 to 80% by mass, and even more preferably from 10 to 75% by mass, of the total solid content of the image recording layer.

[0189] The polymer compound contained in the image recording layer is preferably a polymer compound containing a structural unit derived from a styrene compound and / or a structural unit derived from an acrylonitrile compound. From the viewpoint of contributing to on-press developability, this polymer compound can be suitably used as a binder polymer or polymer particles.

[0190] Examples of the styrene compound include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, and p-methoxy-β-methylstyrene, with styrene being preferred.

[0191] Examples of the acrylonitrile compound include acrylonitrile and methacrylonitrile, with acrylonitrile being preferred.

[0192] In a polymer compound containing a styrene compound and an acrylonitrile compound as constituent units, the composition ratio of the constituent units derived from the styrene compound to the constituent units derived from the acrylonitrile compound is preferably 4:1 to 1:4.

[0193] The image recording layer may contain a color former, a chain transfer agent, a low molecular weight hydrophilic compound, an oil sensitizer, and other components, but preferably contains a color former.

[0194] (color former) The color former preferably contains an acid color former from the viewpoint of color development ability, and the color former preferably contains a leuco compound from the viewpoint of color development ability. Furthermore, the term "acid color former" refers to a compound that has the property of changing the color of the image recording layer by developing or decolorizing a color when heated in a state in which it has accepted an electron-accepting compound (for example, a proton of an acid, etc.). As the acid color former, particularly preferred are colorless compounds that have a partial skeleton such as a lactone, lactam, sultone, spiropyran, ester, or amide, and that rapidly open or cleave this partial skeleton when they come into contact with an electron-accepting compound. In one preferred embodiment, the color former is at least one compound selected from the group consisting of spiropyran compounds, spirooxazine compounds, spirolactone compounds, and spirolactam compounds, from the viewpoint of color development properties. The hue of the dye after color development is preferably green, blue or black from the viewpoint of visibility.

[0195] (chain transfer agent) The chain transfer agent contributes to improving the printing durability of a lithographic printing plate produced from the lithographic printing plate precursor. The chain transfer agent is preferably a thiol compound, more preferably a thiol having 7 or more carbon atoms in terms of boiling point (difficulty of volatilization), and even more preferably a compound having a mercapto group on an aromatic ring (aromatic thiol compound).The thiol compound is preferably a monofunctional thiol compound.

[0196] Specific examples of the chain transfer agent include the following compounds:

[0197] [ka]

[0198] [ka]

[0199] [ka]

[0200] [ka]

[0201] The chain transfer agent may be used alone or in combination of two or more kinds. The content of the chain transfer agent is preferably from 0.01 to 50% by mass, more preferably from 0.05 to 40% by mass, and even more preferably from 0.1 to 30% by mass, based on the total solid content of the image recording layer.

[0202] (Low molecular hydrophilic compound) The low-molecular-weight hydrophilic compound contributes to improving the on-press developability of the lithographic printing plate precursor without reducing the printing durability of the lithographic printing plate produced from the lithographic printing plate precursor. The low-molecular-weight hydrophilic compound is preferably a compound having a molecular weight of less than 1,000, more preferably a compound having a molecular weight of less than 800, and even more preferably a compound having a molecular weight of less than 500. Examples of low-molecular-weight hydrophilic compounds include water-soluble organic compounds such as glycols and their ether or ester derivatives, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol; polyols, such as glycerin, pentaerythritol, and tris(2-hydroxyethyl)isocyanurate; organic amines and their salts, such as triethanolamine, diethanolamine, and monoethanolamine; organic sulfonic acids and their salts, such as alkylsulfonic acid, toluenesulfonic acid, and benzenesulfonic acid; organic sulfamic acids and their salts, such as alkylsulfamic acid; organic sulfuric acids and their salts, such as alkylsulfuric acid and alkyl ether sulfate; organic phosphonic acids and their salts, such as phenylphosphonic acid; organic carboxylic acids and their salts, such as tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, and amino acids; and betaines.

[0203] The low molecular weight hydrophilic compound is preferably at least one selected from polyols, organic sulfates, organic sulfonates, and betaines. As for low molecular weight hydrophilic compounds, those described in

[0145] to

[0147] of WO 2020 / 137919 can be used.

[0204] Low-molecular-weight hydrophilic compounds have a small structure in the hydrophobic portion and have almost no surfactant effect, so the dampening water does not penetrate into the exposed areas (image areas) of the image recording layer and reduce the hydrophobicity or film strength of the image areas, and the ink receptivity and printing durability of the image recording layer can be maintained at a good level.

[0205] The low molecular weight hydrophilic compounds may be used alone or in combination of two or more. The content of the low molecular weight hydrophilic compound is preferably from 0.5 to 20% by mass, more preferably from 1 to 15% by mass, and even more preferably from 2 to 10% by mass, based on the total solid content of the image recording layer.

[0206] (Oil sensitizer) Oil sensitizers contribute to improving the ink receptivity (hereinafter also simply referred to as "ink receptivity") of a lithographic printing plate prepared from a lithographic printing plate precursor. Examples of oil sensitizers include phosphonium compounds, nitrogen-containing low-molecular-weight compounds, and ammonium group-containing polymers. In particular, when the lithographic printing plate precursor has a protective layer containing an inorganic layered compound, these compounds function as a surface coating agent for the inorganic layered compound and have the function of suppressing a decrease in ink receptivity caused by the inorganic layered compound during printing. As the oil-sensitizing agent, it is preferable to use a phosphonium compound, a nitrogen-containing low-molecular-weight compound, and an ammonium group-containing polymer in combination, and it is more preferable to use a phosphonium compound, a quaternary ammonium salt, and an ammonium group-containing polymer in combination. As for the oil sensitizer, those described in

[0151] to

[0155] of WO 2020 / 137919 can be used.

[0207] The content of the oil sensitizer is preferably from 0.01 to 30% by mass, more preferably from 0.1 to 15% by mass, and even more preferably from 1 to 10% by mass, based on the total solid content of the image recording layer.

[0208] (Other ingredients) The image recording layer may contain other components such as surfactants, printing agents, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic particles, inorganic layer compounds, etc. Specifically, the components described in paragraphs 0114 to 0159 of JP-A No. 2008-284817 can be used.

[0209] (Formation of image recording layer) The image recording layer can be formed by dispersing or dissolving the necessary components in a known solvent as appropriate to prepare a coating solution, applying the coating solution by a known method such as bar coater coating, and drying, as described in paragraphs 0142 and 0143 of JP-A No. 2008-195018, for example. The coating amount (solid content) of the image recording layer after coating and drying varies depending on the application, but from the viewpoint of obtaining good sensitivity and good film properties of the image recording layer, it is 0.3 to 3.0 g / m 2 The degree is preferable.

[0210] From the viewpoint of imparting on-press developability, the image recording layer is preferably water-soluble or water-dispersible. Here, "water-soluble" means that 0.1 g or more of the image recording layer dissolves in 100 g of water at 20° C., and "water-dispersible" means that the image recording layer is uniformly dispersed in water at 20° C.

[0211] The on-press development type lithographic printing plate precursor can have an undercoat layer (sometimes called an intermediate layer) between the image recording layer and the support, and a protective layer (sometimes called an overcoat layer) on the image recording layer.

[0212] [Undercoat layer] The undercoat layer strengthens the adhesion between the support and the image recording layer in the exposed areas and facilitates peeling of the image recording layer from the support in the unexposed areas, thereby contributing to improving developability without impairing printing durability. In addition, in the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, thereby preventing the heat generated by exposure from diffusing to the support and reducing sensitivity.

[0213] Compounds used in the undercoat layer include polymers having an adsorptive group and a hydrophilic group that can be adsorbed to the support surface. Polymers having an adsorptive group and a hydrophilic group and also a crosslinkable group are preferred to improve adhesion to the image recording layer. The compounds used in the undercoat layer may be low-molecular-weight compounds or polymers. Two or more compounds may be mixed together as needed.

[0214] When the compound used in the undercoat layer is a polymer, it is preferably a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group. Preferred adsorptive groups that can be adsorbed onto the surface of a support include phenolic hydroxy groups, carboxy groups, -PO3H2, -OPO3H2, -CONHSO2-, -SON2NHSO2-, and -COCH2COCH3. Preferred hydrophilic groups include sulfo groups or salts thereof, and carboxy group salts. Preferred crosslinkable groups include acrylic groups, methacrylic groups, acrylamide groups, methacrylamide groups, and allyl groups. The polymer may have a crosslinkable group introduced by salt formation between a polar substituent of the polymer and a compound having an ethylenically unsaturated bond and a substituent having an opposite charge to the polar substituent, or may be further copolymerized with a monomer other than the above, preferably a hydrophilic monomer.

[0215] Specific examples of suitable compounds include silane coupling agents having an addition-polymerizable ethylenic double bond reactive group, as described in JP-A-10-282679, and phosphorus compounds having an ethylenic double bond reactive group, as described in JP-A-2-304441. Also preferred are low-molecular-weight or high-molecular-weight compounds having a crosslinkable group (preferably an ethylenically unsaturated bond group), a functional group that interacts with the support surface, and a hydrophilic group, as described in JP-A-2005-238816, JP-A-2005-125749, JP-A-2006-239867, and JP-A-2006-215263. More preferred examples include high molecular weight polymers having adsorptive groups, hydrophilic groups, and crosslinkable groups that can be adsorbed onto the surface of a support, as described in JP-A Nos. 2005-125749 and 2006-188038.

[0216] The content of the ethylenically unsaturated bond group in the polymer used in the undercoat layer is preferably 0.1 to 10.0 mmol, more preferably 0.2 to 5.5 mmol, per 1 g of the polymer. The mass average molecular weight (Mw) of the polymer used in the undercoat layer is preferably 5,000 or more, more preferably from 10,000 to 300,000.

[0217] In addition to the above-described compounds for the undercoat layer, the undercoat layer may contain a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, a compound having an amino group or a functional group having polymerization inhibitory ability and a group that interacts with the support surface (e.g., 1,4-diazabicyclo[2.2.2]octane (DABCO), 2,3,5,6-tetrahydroxy-p-quinone, chloranil, sulfophthalic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, etc.), etc., to prevent contamination over time.

[0218] The undercoat layer can be formed by coating and drying using a known method. The coating amount (solid content) of the undercoat layer after drying is 0.1 to 100 mg / m 2 is preferred, and 1 to 30 mg / m 2 is more preferred.

[0219] [Protective layer] The protective layer has the function of inhibiting image formation inhibiting reactions by blocking oxygen, as well as the function of preventing scratches on the image recording layer and ablation during exposure to high-intensity laser light.

[0220] Protective layers with such properties are described, for example, in U.S. Pat. No. 3,458,311 and Japanese Patent Publication No. 55-49729. The low-oxygen-permeable polymer used in the protective layer can be selected from either a water-soluble polymer or a water-insoluble polymer, and two or more types can be mixed as needed. Specific examples include polyvinyl alcohol resins (including polyvinyl alcohol and modified polyvinyl alcohol), polyvinylpyrrolidone, water-soluble cellulose derivatives, and poly(meth)acrylonitrile. The polyvinyl alcohol is preferably one having a degree of saponification of 50% or more. The degree of saponification of polyvinyl alcohol is preferably 60% or more, more preferably 70% or more, and even more preferably 85% or more. There is no particular upper limit to the degree of saponification, and it is sufficient that the degree of saponification is 100% or less. The degree of saponification can be measured according to the method described in JIS K 6726:1994. The modified polyvinyl alcohol is preferably an acid-modified polyvinyl alcohol having a carboxy group or a sulfo group, and specific examples thereof include the modified polyvinyl alcohols described in JP-A Nos. 2005-250216 and 2006-259137. Among the water-soluble polymers, polyvinyl alcohol resins are preferred.

[0221] The protective layer preferably contains an inorganic layered compound to enhance oxygen blocking properties. The inorganic layered compound is a thin, tabular particle, and examples thereof include mica such as natural mica and synthetic mica, talc represented by the formula 3MgO 4SiO HO, taeniolite, montmorillonite, saponite, hectorite, and zirconium phosphate. The inorganic layer compound preferably used is a mica compound. Examples of the mica compound include those represented by the formula: A(B,C) 2-5 D4O 10 Examples of micas include natural mica and synthetic mica represented by the formula (OH,F,O)2 (wherein A is K, Na, or Ca; B and C are Fe(II), Fe(III), Mn, Al, Mg, or V; and D is Si or Al).

[0222] In the mica group, natural micas include muscovite, sodalite, phlogopite, biotite, and lepidolite. Synthetic micas include fluorphlogopite KMg3(AlSiO 10 )F2, potassium tetrasilicic mica KMg 2.5 SiO 10 )F2 and other non-swelling micas, and Na tetrasilicic mica NaMg 2.5 (SiO 10 )F2, Na or Li taeniolite (Na,Li)Mg2Li(SiO 10 ) F2, Na or Li hectorite of the montmorillonite series (Na, Li) 1 / 8 Mg 2 / 5 Li 1 / 8 (SiO 10Examples include swelling micas such as )F2. Synthetic smectite is also useful.

[0223] Among mica compounds, fluorine-based swellable mica is particularly useful. That is, swellable synthetic mica has a layered structure consisting of unit crystal lattice layers about 10 to 15 Å thick, and the metal atom substitution within the lattice is significantly greater than that of other clay minerals. As a result, the lattice layers have a lack of positive charge, and to compensate for this, Li is inserted between the layers. + , Na + , Ca 2+ , Mg 2+ The cations present between these layers are called exchangeable cations and can be exchanged with various cations. In particular, the cations between the layers are Li + , Na + In the case of mica, the ionic radius is small, so the bonds between the layered crystal lattices are weak, and it swells greatly in water. When shear is applied in this state, it cleaves easily and forms a stable sol in water. Swellable synthetic mica has a strong tendency in this regard, and is particularly preferred.

[0224] Regarding the shape of the mica compound, from the viewpoint of diffusion control, the thinner the thickness, the better, and the larger the planar size, the better, as long as it does not impair the smoothness of the coated surface or the transmittance of actinic rays. Therefore, the aspect ratio is preferably 20 or more, more preferably 100 or more, and particularly preferably 200 or more. The aspect ratio is the ratio of the major axis to the thickness of the particle, and can be measured, for example, from a projection view of a particle in a micrograph. The larger the aspect ratio, the greater the effect obtained.

[0225] The particle size of the mica compound is preferably 0.3 to 20 μm, more preferably 0.5 to 10 μm, and particularly preferably 1 to 5 μm, in terms of average major axis. The average particle thickness is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.01 μm or less. Specifically, for example, in the case of swellable synthetic mica, a representative compound, a preferred embodiment is one in which the thickness is about 1 to 50 nm and the face size (major axis) is about 1 to 20 μm.

[0226] The content of the inorganic layer compound is preferably 0 to 60% by mass, more preferably 3 to 50% by mass, based on the total solid content of the protective layer. Even when multiple types of inorganic layer compounds are used in combination, the total amount of the inorganic layer compounds is preferably within the above content range. Within the above range, oxygen barrier properties are improved, good sensitivity is obtained, and a decrease in ink receptivity can be prevented.

[0227] The protective layer may contain known additives such as a plasticizer for imparting flexibility, a surfactant for improving coating properties, inorganic fine particles for controlling surface slippage, etc. The protective layer may also contain an oil-sensitizing agent as described for the image-recording layer.

[0228] The protective layer can be formed by coating and drying using a known method. The coating amount (solid content) of the protective layer after drying is 0.01 to 10 g / m 2 is preferable, and 0.02 to 3 g / m 2 More preferably, 0.02 to 1 g / m 2 is particularly preferred.

[0229] The on-press development type lithographic printing plate precursor according to the present invention has a droop shape at the edge portion.

[0230] FIG. 3 is a schematic diagram showing the cross-sectional shape of an edge portion of a planographic printing plate precursor. 3, the lithographic printing plate precursor 1 has a sag 2 at its edge. The distance X from the upper end of the edge surface 1c of the lithographic printing plate precursor 1 (the boundary point between the sag 2 and the edge surface 1c) to the intersection point between an extension of the edge surface 1c and an extension of the image recording layer surface 1a (the protective layer surface if a protective layer is formed) is referred to as the "sag amount X," and the distance Y from the point where the image recording layer surface 1a of the lithographic printing plate precursor 1 starts to sag to the intersection point is referred to as the "sag width Y."

[0231] Regarding the sagging shape of the edge, the sagging amount X is preferably 25 μm or more, more preferably 35 μm or more, and even more preferably 40 μm or more. The upper limit of the sagging amount X is preferably 150 μm from the viewpoint of preventing deterioration of on-press developability due to deterioration of the edge surface condition. Deterioration of on-press developability may cause ink to adhere to the remaining image recording layer, resulting in edge smearing. If the sagging amount X is too small, ink adhered to the edge may be more likely to transfer to the blanket, resulting in edge smearing. When the sagging amount X is in the range of 25 to 150 μm, a small sagging width Y may increase the occurrence of cracks at the edge, which may result in accumulation of printing ink there, resulting in edge smearing. From this viewpoint, the sagging width Y is preferably in the range of 70 to 300 μm, more preferably 80 to 250 μm. The above sagging amount and sagging width ranges are not related to the edge shape of the support surface 1b of the lithographic printing plate precursor 1. Generally, at the edge of the lithographic printing plate precursor 1, sagging occurs at the boundary B between the image recording layer and the support, and on the support surface 1b, similar to the image recording layer surface 1a.

[0232] The formation of the drooped edge portion can be achieved, for example, by adjusting the cutting conditions of the lithographic printing plate precursor. Specifically, this can be achieved by adjusting the gap between the upper and lower cutting blades, the amount of engagement, the blade angle, etc. of the slitter device used when cutting the planographic printing plate precursor. FIG. 4 is a conceptual diagram showing an example of the cutting section of a slitter device. The slitter device has a pair of upper and lower cutting blades 10 and 20 arranged one above the other. The cutting blades 10 and 20 are circular, disk-shaped blades, with the upper cutting blades 10a and 10b coaxially supported on a rotating shaft 11 and the lower cutting blades 20a and 20b coaxially supported on a rotating shaft 21. The upper cutting blades 10a and 10b and the lower cutting blades 20a and 20b rotate in opposite directions. The planographic printing plate precursor 30 is cut to a predetermined width by passing between the upper cutting blades 10a and 10b and the lower cutting blades 20a and 20b. By adjusting the gap between the upper cutting blade 10a and the lower cutting blade 20a and the gap between the upper cutting blade 10b and the lower cutting blade 20b in the cutting section of the slitter device, it is possible to form an edge having a drooped shape.

[0233] It is preferable that the planographic printing plate precursor has an ink repellent agent on part or all of the two opposing side surfaces. By applying an ink repellent agent to part or all of the two opposing side surfaces of the end portion having the drooped shape, edge staining at the edge portion can be suppressed. The ink repellent agent is not particularly limited as long as it can repel ink, and for example, a hydrophilizing agent or a desensitizing liquid can be used. Materials used as the ink repellent agent are described below.

[0234] (hydrophilizing agent) One preferred embodiment of the hydrophilizing agent is a phosphate compound. Phosphate compounds include phosphoric acid, its salts, and its esters. Examples include phosphoric acid, metaphosphoric acid, monoammonium phosphate, diammonium phosphate, sodium dihydrogen phosphate, sodium monohydrogen phosphate, potassium monophosphate, potassium dihydrogen phosphate, sodium tripolyphosphate, potassium pyrophosphate, and sodium hexametaphosphate. Among these, sodium dihydrogen phosphate, sodium monohydrogen phosphate, and sodium hexametaphosphate are preferred.

[0235] The phosphoric acid compound is preferably a polymeric compound, more preferably a polymeric compound having a phosphate ester group. Examples of the polymeric compound having a phosphate ester group include a polymer composed of one or more monomers having a phosphate ester group in the molecule, a copolymer of one or more monomers having a phosphate ester group and one or more monomers not having a phosphate ester group, and a polymer in which a phosphate ester group has been introduced into a polymer not having a phosphate ester group by a polymer reaction.

[0236] In the polymer compound having a phosphate ester group, the content of the repeating unit having a phosphate ester group is preferably 1 to 100 mol %, more preferably 5 to 100 mol %, and even more preferably 10 to 100 mol %, based on the total repeating units of the polymer compound. The mass average molecular weight of the polymer compound having a phosphate ester group is preferably 5,000 to 1,000,000, more preferably 7,000 to 700,000, and even more preferably 10,000 to 500,000.

[0237] A preferred embodiment of the hydrophilizing agent is a phosphonic acid compound. The phosphonic acid compound includes phosphonic acid, its salts, and its esters. Examples include ethylphosphonic acid, propylphosphonic acid, isopropylphosphonic acid, butylphosphonic acid, hexylphosphonic acid, octylphosphonic acid, dodecylphosphonic acid, octadecylphosphonic acid, 2-hydroxyethylphosphonic acid, and their sodium or potassium salts; alkylphosphonic acid monoalkyl esters, such as methyl methylphosphonate, methyl ethylphosphonate, and methyl 2-hydroxyethylphosphonate, and their sodium or potassium salts; alkylene diphosphonic acids, such as methylene diphosphonic acid and ethylene diphosphonic acid, and their sodium or potassium salts; and polyvinylphosphonic acid.

[0238] A preferred embodiment of the hydrophilizing agent is a water-soluble resin. Examples of water-soluble resins include those classified as polysaccharides, such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide and its copolymers, vinyl methyl ether / maleic anhydride copolymers, vinyl acetate / maleic anhydride copolymers, and styrene / maleic anhydride copolymers. Examples of polysaccharides include starch derivatives (e.g., dextrin, enzymatically hydrolyzed dextrin, hydroxypropylated starch, carboxymethylated starch, phosphated starch, polyoxyalkylene-grafted starch, and cyclodextrin), celluloses (e.g., carboxymethylcellulose, carboxyethylcellulose, methylcellulose, hydroxypropylcellulose, and methylpropylcellulose), carrageenan, alginic acid, guar gum, locust bean gum, xanthan gum, gum arabic, and soybean polysaccharides. The water-soluble resin is preferably dextrin, a starch derivative such as polyoxyalkylene-grafted starch, gum arabic, carboxymethyl cellulose, or soybean polysaccharide.

[0239] Preferred embodiments of the hydrophilizing agent include anionic surfactants and nonionic surfactants. Examples of anionic surfactants include those described in paragraph

[0022] of JP 2014-104631 A, the contents of which are incorporated herein by reference. Preferred anionic surfactants include dialkyl sulfosuccinates, alkyl sulfate ester salts, polyoxyethylene aryl ether sulfate ester salts, and alkyl naphthalene sulfonates. Preferred anionic surfactants are those represented by general formula (IA) or general formula (IB).

[0240] [ka]

[0241] In general formula (IA), R 1 represents a linear or branched alkyl group having 1 to 20 carbon atoms, p represents 0, 1 or 2, and Ar1 represents an aryl group having 6 to 10 carbon atoms, q represents 1, 2 or 3, M1 + Na + , K. + , Li + or NH4 + If p is 2, there are multiple R 1 may be the same or different from each other.

[0242] In general formula (IB), R 2 represents a linear or branched alkyl group having 1 to 20 carbon atoms, m represents 0, 1 or 2, and Ar 2 represents an aryl group having 6 to 10 carbon atoms, Y represents a single bond or an alkylene group having 1 to 10 carbon atoms, R 3 represents a linear or branched alkylene group having 1 to 5 carbon atoms, n represents an integer of 1 to 100, M2 + Na + , K. + , Li + or NH4 + If m is 2, there are multiple R 2 may be the same or different, and when n is 2 or more, multiple R 3 may be the same or different from each other.

[0243] In general formula (IA) and general formula (IB), R 1 and R 2 is preferably CH3, C2H5, C3H7 or C4H9. 3 is preferably -CH2-, -CH2CH2-, -CH2CH2CH2- or -CH2CH(CH3)-, more preferably -CH2CH2-. p and m are preferably 0 or 1, more preferably p is 0. Y is preferably a single bond. n is preferably an integer of 1 to 20.

[0244] Examples of nonionic surfactants include those described in paragraph

[0031] of JP 2014-104631 A, the contents of which are incorporated herein by reference. Preferred nonionic surfactants are polyoxyethylene aryl ethers and polyoxyethylene-polyoxypropylene block copolymers.

[0245] The nonionic surfactant is preferably a nonionic surfactant represented by general formula (II-A).

[0246] [ka]

[0247] In general formula (II-A), R 4 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, s represents 0, 1 or 2, and Ar 3 represents an aryl group having 6 to 10 carbon atoms, and t and u each represent an integer of 0 to 100, provided that both t and u are not 0. When s is 2, multiple R4s may be the same or different.

[0248] The hydrophilizing agent may be organic resin particles (e.g., microgel). Microgels are reactive or non-reactive resin particles dispersed in an aqueous medium. The microgel preferably has polymerizable groups in or on the particle surface.

[0249] The coating liquid containing a hydrophilizing agent is preferably in the form of an aqueous solution in which the hydrophilizing agent is dissolved or dispersed in a medium mainly consisting of water. The content of the hydrophilizing agent in the coating liquid containing a hydrophilizing agent is preferably 0.05 to 50 mass %, more preferably 0.1 to 30 mass %. The viscosity of the coating liquid containing a hydrophilizing agent is preferably 0.5 to 1000 mPa·s, more preferably 1 to 100 mPa·s, at 25°C. The surface tension of the coating liquid containing a hydrophilizing agent is preferably 25 to 70 mN / m, more preferably 40 to 65 mN / m, at 25°C.

[0250] The coating liquid containing a hydrophilizing agent may contain, in addition to the hydrophilizing agent, an organic solvent, a plasticizer, a preservative, an antifoaming agent, and inorganic salts such as nitrates and sulfates.

[0251] (Degreasing liquid) Examples of desensitizing solutions include aqueous solutions containing at least one of a hydrophilic organic polymer, hexametaphosphoric acid and its salts, and phytic acid and its salts. Specific examples of hydrophilic organic polymers include gum arabic, dextrin, alginates such as sodium alginate, water-soluble celluloses such as carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, water-soluble copolymers containing acrylamide units, polyacrylic acid, copolymers containing acrylic acid units, polyacrylic acid, copolymers containing acrylic acid units, polymethacrylic acid, copolymers containing methacrylic acid units, copolymers of vinyl methyl ether and maleic anhydride, copolymers of vinyl acetate and maleic anhydride, and phosphate-modified starch. Among these, gum arabic is preferred due to its strong desensitizing effect. These hydrophilic polymers can be used in combination, if necessary, at a concentration of about 1 to 40% by weight, preferably 3 to 30% by weight.

[0252] Specific examples of hexametaphosphates include alkali metal or ammonium hexametaphosphates. Examples of alkali metal or ammonium hexametaphosphates include sodium hexametaphosphate, potassium hexametaphosphate, and ammonium hexametaphosphate. Specific examples of phytic acid or its salts include alkali metal salts such as sodium, potassium, and lithium salts, ammonium salts, and amine salts. Examples of amine salts include salts of diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, n-butylamine, n-amylamine, n-hexylamine, laurylamine, ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, ethanolamine, diethanolamine, triethanolamine, allylamine, and aniline. Phytic acid salts may be normal salts in which all 12 acid hydrogen atoms have been replaced, or hydrogen salts (acid salts) in which some of the acid hydrogen atoms have been replaced, and may also be in the form of simple salts consisting of a single base or double salts containing two or more bases as components. These compounds may be used alone or in combination of two or more.

[0253] The desensitizing solution used in this embodiment preferably further contains a metal salt of a strong acid, thereby enhancing the desensitizing effect. Specific examples of metal salts of strong acids include sodium, potassium, magnesium, calcium, and zinc salts of nitrate; sodium, potassium, magnesium, calcium, and zinc salts of sulfate; sodium, potassium, magnesium, calcium, and zinc salts of chromate; and sodium and potassium fluoride. Two or more of these metal salts of strong acids can be used in combination, with the amount preferably being about 0.01 to 5 wt. % based on the total weight of the desensitizing solution. The pH of the desensitizing solution used in this invention is adjusted to an acidic range, preferably 1 to 5, and most preferably 1.5 to 4.5. Therefore, if the pH of the aqueous phase is not acidic, an acid is added to the aqueous phase. Examples of acids that can be added as such pH adjusters include mineral acids such as phosphoric acid, sulfuric acid, and nitric acid, and organic acids such as citric acid, ammonium phosphoric acid, malic acid, glacial acetic acid, lactic acid, oxalic acid, p-toluenesulfonic acid, and organic phosphonic acids. Of these, phosphoric acid is particularly excellent because it not only functions as a pH adjuster but also has the effect of strengthening the desensitizing action, and it is preferable to add phosphoric acid in an amount of 0.01 to 20% by weight, and most preferably 0.1 to 10% by weight, based on the total weight of the desensitizing solution.

[0254] The desensitizing solution used in this embodiment preferably contains a wetting agent and / or surfactant, which improves the applicability of the desensitizing solution. Specific wetting agents include lower polyhydric alcohols, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, pentanediol, hexylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, glycerin, sorbitol, and pentaerythritol, with glycerin being particularly preferred. Surfactants that can be used include nonionic surfactants such as polyoxyethylene alkylphenyl ether and polyoxyethylene polyoxypropylene block copolymers; anionic surfactants such as fatty acid salts, alkyl sulfate ester hydrochlorides, alkylbenzene sulfonates, alkylnaphthalene sulfonates, dialkyl sulfosuccinate ester salts, alkyl phosphate ester salts, and naphthalene sulfonate-formalin condensates; and amphoteric surfactants such as betaine, glycine, alanine, and sulfobetaine. These wetting agents and / or surfactants are contained in the range of about 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the total weight of the desensitizing liquid. The desensitizing liquid used in the present invention may further contain fillers such as silicon dioxide, talc, clay, etc. in an amount of up to 2% by weight, and dyes, pigments, etc. in an amount of up to 1% by weight.

[0255] The desensitizing liquid used in this embodiment is a hydrophilic aqueous solution as described above. However, in consideration of possible adverse effects on the image recording layer, an emulsion-type desensitizing liquid such as those described in U.S. Pat. Nos. 4,253,999, 4,268,613, and 4,348,954 may also be used.

[0256] As the ink repellent agent, for example, HN-G5 (manufactured by Fujifilm Corporation) can be used.

[0257] (Method of applying ink repellent) The method for applying the ink-repellent agent is not particularly limited. FIG. 7 is a diagram illustrating a method for applying the ink-repellent agent. As shown in FIG. 7, a coating liquid containing the ink-repellent agent can be applied using a wire bar 138. Note that in FIG. 7, in order to explain the method for applying the ink-repellent agent, the lithographic printing plate precursor 100a having the outermost layer surface 122 on the specific component layer side relative to the support is depicted in a simplified manner, and the shape of the sagging at the edge is not depicted. When applying the ink-repellent agent using the wire bar 138, first, the coating liquid containing the ink-repellent agent is applied to the wire bar 138. The wire bar 138 with the coating liquid applied thereto is moved so as to follow the edge surface 120 (the side surface of the aluminum support) of the lithographic printing plate precursor 100a. The wire bar 138 can be moved at a speed of, for example, 20 mm / s. After application, the coating liquid is dried. As drying conditions, for example, drying can be performed by exposing the substrate to air at 80° C. at a speed of 6 m / s for 30 seconds. The size of the wire bar can be changed as appropriate depending on the thickness of the aluminum support of the lithographic printing plate precursor 100a. For example, if the thickness of the aluminum support is 0.3 mm, a wire bar with a mesh size of #10 can be used.

[0258] Furthermore, when applying the coating liquid, as shown in FIG. 7, the wire bar 138 may be tilted at an angle θ with respect to the edge surface 120 of the lithographic printing plate precursor 100a. As a method for applying the ink repellent agent to a part or the whole of the two opposing side surfaces of the lithographic printing plate precursor, the method described in Japanese Patent No. 6628949 can be suitably used.

[0259] In the on-press development type lithographic printing plate precursor according to the present invention, the arithmetic mean height Sa of the outermost layer surface on the side having the image recording layer is preferably 0.3 to 20.0 μm, where the side having the image recording layer means the side having the image recording layer relative to the support.

[0260] When the image recording layer or the protective layer is the outermost layer, the outermost surface on the side having the image recording layer is the surface of the image recording layer or the surface of the protective layer. For example, when forming protrusions as described below, the lithographic printing plate precursor may have the image recording layer or protective layer as the outermost layer, and may have a plurality of protrusions containing a polymer compound on the outside of the image recording layer or protective layer.

[0261] The arithmetic mean height Sa of the outermost layer surface on the side having the image recording layer is more preferably 0.5 to 10.0 μm, and even more preferably 0.5 to 7.0 μm.

[0262] In order to achieve the requirement that the arithmetic mean height Sa of the outermost layer surface be 0.3 to 20.0 μm, it is preferable that the outermost layer be formed into a shape having projections and recesses. Specifically, for example, there are mentioned an embodiment in which the outermost layer contains particles having an average particle size of 0.5 to 20.0 μm (Embodiment 1A), and an embodiment in which the outermost layer has a plurality of protrusions containing a polymer compound as a main component on the outside (Embodiment 2A). Here, the main component means the component with the highest content (% by mass).

[0263] Aspect 1A is the same as Aspect 1 above, and the preferred ranges are also the same. The outermost surface in embodiment 1 is the outermost surface on the side opposite to the side having the image recording layer, and the outermost surface in embodiment 1A is the outermost surface on the side having the image recording layer.

[0264] Examples of the polymer compound constituting the plurality of protrusions containing a polymer compound as a main component in Aspect 2A include novolak resins such as phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, and phenol / cresol (m-, p-, or m- / p-mixed) mixed formaldehyde resin, resol resin, pyrogallol acetone resin, epoxy resin, saturated copolymer polyester resin, phenoxy resin, polyvinyl acetal resin, vinylidene chloride copolymer resin, polybutene, and polybutadiene. At least one polymer compound selected from the group consisting of polyamide, unsaturated copolymer polyester resin, polyurethane, polyurea, polyimide, polysiloxane, polycarbonate, epoxy resin, chlorinated polyethylene, aldehyde condensation resin of alkylphenol, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylate, carboxyvinyl polymer, acrylic resin copolymer resin, hydroxycellulose, hydroxymethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, cellulose acetate, methylcellulose, and carboxymethylcellulose is preferred.

[0265] Among these, water-soluble polymers are more preferred from the viewpoint of excellent developability even when the detached protrusions move to the image recording layer. Specific examples include polyacrylates, carboxyvinyl polymers, acrylic resin copolymer resins, hydroxycellulose, hydroxymethylcellulose, polyvinyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, cellulose acetate, methylcellulose, and carboxymethylcellulose. The modified polyvinyl alcohol is preferably an acid-modified polyvinyl alcohol having a carboxy group or a sulfo group, specifically the modified polyvinyl alcohols described in JP-A Nos. 2005-250216 and 2006-259137.

[0266] The shape and height of the protrusions are not particularly limited, but it is preferable that the arithmetic mean height Sa is 0.3 to 20.0 μm. The method for forming the protrusions can be the same as that described above for the backcoat layer.

[0267] Examples of the binder contained in the outermost layer in Aspect 2A include polymer compounds similar to those contained in the protrusions, and the same applies to preferred aspects. In Aspect 2A, from the viewpoint of preventing detachment of the protrusions, it is preferable that the binder contained in the outermost layer and the polymer compound contained in the protrusions contain the same type of resin. Here, "the same type of resin" means that the resin type is the same, such as polyurethane, acrylic resin, polystyrene, or polyethylene, and it is not necessary that all of the structural units in the resin are the same.

[0268] [How to make a printing plate] The method for producing a printing plate according to the present invention will be described using the lithographic printing plate precursor according to the present invention. The method for producing a printing plate includes a step of imagewise exposing the lithographic printing plate precursor (exposure step), and a step of removing the unexposed portion of the image recording layer of the lithographic printing plate precursor after imagewise exposure on a printing press with at least one of printing ink and fountain solution (on-press development step).

[0269] [Exposure process] Image exposure is preferably carried out by scanning and exposing digital data with an infrared laser or the like. The wavelength of the exposure light source is preferably 750 to 1,400 nm. A solid-state laser or semiconductor laser that emits infrared light is suitable as the light source having a wavelength of 750 to 1,400 nm. The exposure mechanism may be any of an internal drum system, an external drum system, or a flatbed system. The exposure step can be carried out by a known method using a plate setter, etc. Alternatively, after the lithographic printing plate precursor is mounted on a printing press equipped with an exposure device, image exposure may be carried out on the printing press.

[0270] [On-press development process] In the on-press development process, when printing is started by supplying printing ink and fountain solution to the lithographic printing plate precursor on the printing press without any development treatment after image exposure, the unexposed parts of the lithographic printing plate precursor are removed in the early stages of printing, thereby exposing the surface of the hydrophilic support and forming non-image parts. As the printing ink and fountain solution, known printing inks and fountain solutions for lithographic printing are used. Either the printing ink or the fountain solution may be supplied first to the surface of the printing plate precursor, but it is preferable to supply the printing ink first in order to prevent the fountain solution from being contaminated by the removed image-recording layer components. In this way, the lithographic printing plate precursor is developed on the offset printing press and is used as is for printing a large number of sheets.

[0271] The method for producing a printing plate according to the present invention may include other known steps in addition to the steps described above, such as a plate inspection step for checking the position and orientation of the lithographic printing plate precursor before each step, and a confirmation step for checking the printed image after the on-press development step. [Example]

[0272] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In the examples, "%" and "parts" mean "% by mass" and "parts by mass", respectively, unless otherwise specified. In polymer compounds, unless otherwise specified, the molecular weight is the mass average molecular weight (Mw), and the ratio of the constituent repeating units is expressed as a molar percentage. The mass average molecular weight (Mw) is a value measured as a polystyrene equivalent value by gel permeation chromatography (GPC).

[0273] [Examples 1 to 31 and Comparative Examples 1 to 3]

[0274] <Preparation of Support 1-1> (Preparation of aluminum alloy 1-1) An ingot was produced by DC casting using molten aluminum containing 0.020% by mass of magnesium. Next, the ingot was subjected to facing, followed by soaking at 550°C for 5 hours. After the soaking, the ingot was hot-rolled when the temperature dropped to 440°C. Further, intermediate annealing, cold rolling (reduction rate 96%), and forcing were appropriately performed to finish the ingot to a thickness of 0.30 mm, thereby obtaining Aluminum Alloy 1-1. The reduction ratio is calculated by (h1-h2) / h1, where h1 and h2 are the thicknesses of the material before and after rolling, and represents the degree of processing in rolling.

[0275] (Preparation of Support 1-1) The aluminum alloy 1-1 was subjected to the following treatments (Fa) to (Fg) to prepare a support 1-1. Note that water rinsing was performed between all treatment steps, and after the water rinsing, the liquid was removed using nip rollers.

[0276] (Fa) Alkaline etching treatment An aluminum plate was etched by spraying an aqueous solution of caustic soda with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at a temperature of 70°C. The amount of dissolved aluminum on the surface to be subsequently subjected to electrochemical graining treatment was 5 g / m 2 It was.

[0277] (Fb) Desmutting treatment using an acidic aqueous solution As the acidic aqueous solution, an aqueous solution with a sulfuric acid concentration of 150 g / L and a liquid temperature of 30° C. was sprayed onto the aluminum plate for 3 seconds to perform a desmutting treatment.

[0278] (Fc) Electrochemical roughening treatment Electrochemical graining treatment was performed using an electrolytic solution with a hydrochloric acid concentration of 14 g / L, an aluminum ion concentration of 13 g / L, and a sulfuric acid concentration of 3 g / L, using an alternating current. The temperature of the electrolytic solution was 30°C. The aluminum ion concentration was adjusted by adding aluminum chloride. The AC waveform is a sine wave with symmetrical positive and negative waveforms, the frequency is 50 Hz, the anode reaction time and cathode reaction time in one AC cycle are 1:1, and the current density is 75 A / dm at the peak current value of the AC waveform. 2 The total amount of electricity that the aluminum plate takes in the anode reaction is 450 C / dm 2 and electrolytic treatment is 112.5C / dm 2 The test was carried out four times with a 4-second interval between each test. A carbon electrode was used as the counter electrode to the aluminum plate.

[0279] (Fd) Alkaline etching treatment An aluminum plate was etched by spraying an aqueous solution of caustic soda with a caustic soda concentration of 5% by mass and an aluminum ion concentration of 0.5% by mass at a temperature of 45°C. The amount of dissolved aluminum on the electrochemically roughened surface was 0.2 g / m 2 It was.

[0280] (Fe) Desmutting treatment using an acidic aqueous solution The acidic aqueous solution was an aqueous solution with a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L at a liquid temperature of 35° C., which was sprayed onto the aluminum plate for 3 seconds to perform desmutting.

[0281] (Ff) First stage anodizing The first stage of anodizing treatment was carried out using a DC electrolysis anodizing apparatus with the structure shown in Figure 6. A 150 g / L aqueous phosphoric acid solution was used as the electrolyte, and the solution temperature was 35°C and the current density was 4.5 A / dm 2 Anodizing treatment was performed under the conditions of 1g / m 2 An anodic oxide film was formed.

[0282] (Fg) Second stage anodizing The second stage of anodizing treatment was carried out using a DC electrolysis anodizing apparatus with the structure shown in Figure 6. A 170 g / L aqueous sulfuric acid solution was used as the electrolyte, and the solution temperature was 50°C and the current density was 13 A / dm 2 Anodizing treatment was performed under the conditions of 2.1 g / m 2An anodic oxide film of the above formula was formed. The substrate was then washed with water by spraying. The average diameter of the micropores in Support 1-1 was 40 nm. The lightness L* value of the anodized film surface of Support 1-1 in the L*a*b* color system was 83.7.

[0283] The tensile strength of the obtained support 1-1 was 160 MPa. The tensile strength was measured using an autograph AGC-H5KN (manufactured by Shimadzu Corporation) as a tensile strength measuring device, with a sample being a JIS metal material tensile test piece No. 5, at a tension speed of 2 mm / min. The magnesium content in the support 1-1 was 0.020% by mass. The magnesium content was measured as described above.

[0284] <Preparation of Supports 1-2 to 1-10> Aluminum alloys 1-2 to 1-10 were prepared in the same manner as in the preparation of Support 1-1, except that the rolling reduction and magnesium content were changed as shown in Table 1, to prepare Supports 1-2 to 1-10.

[0285] <Preparation of Support 2> (Preparation of aluminum alloy 2) Aluminum alloy 2 was produced in the same manner as in the production of aluminum alloy 1-1, except that the magnesium content and rolling reduction were changed as shown in Table 1. (Preparation of Support 2) The aluminum alloy 2 was subjected to the following treatments (Fa) to (Ff) to prepare a support 2. Water rinsing treatment was carried out between all treatment steps, and after the water rinsing treatment, the liquid was removed using nip rollers.

[0286] (Fa) Alkaline etching treatment An aluminum plate was etched by spraying an aqueous solution of caustic soda with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at a temperature of 70°C. The amount of dissolved aluminum on the surface to be subsequently subjected to electrochemical graining treatment was 5 g / m 2 It was.

[0287] (Fb) Desmutting treatment using an acidic aqueous solution As the acidic aqueous solution, an aqueous solution with a sulfuric acid concentration of 150 g / L and a liquid temperature of 30° C. was sprayed onto the aluminum plate for 3 seconds to perform a desmutting treatment.

[0288] (Fc) Electrochemical roughening treatment Electrochemical graining treatment was performed using an electrolytic solution with a hydrochloric acid concentration of 14 g / L, an aluminum ion concentration of 13 g / L, and a sulfuric acid concentration of 3 g / L, using an alternating current. The temperature of the electrolytic solution was 30°C. The aluminum ion concentration was adjusted by adding aluminum chloride. The AC waveform is a sine wave with symmetrical positive and negative waveforms, the frequency is 50 Hz, the anode reaction time and cathode reaction time in one AC cycle are 1:1, and the current density is 75 A / dm at the peak current value of the AC waveform. 2 The total amount of electricity that the aluminum plate takes in the anode reaction is 450 C / dm 2 and electrolytic treatment is 112.5C / dm 2 The test was carried out four times with a 4-second interval between each test. A carbon electrode was used as the counter electrode to the aluminum plate.

[0289] (Fd) Alkaline etching treatment An aluminum plate was etched by spraying an aqueous solution of caustic soda with a caustic soda concentration of 5% by mass and an aluminum ion concentration of 0.5% by mass at a temperature of 45°C. The amount of dissolved aluminum on the electrochemically roughened surface was 0.2 g / m 2 It was.

[0290] (Fe) Desmutting treatment using an acidic aqueous solution The acidic aqueous solution was an aqueous solution with a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L at a liquid temperature of 35° C., which was sprayed onto the aluminum plate for 3 seconds to perform desmutting.

[0291] (Ff) First stage anodizing The first stage of anodizing treatment was carried out using a DC electrolysis anodizing apparatus with the structure shown in Figure 6. A 150 g / L aqueous phosphoric acid solution was used as the electrolyte, and the solution temperature was 35°C and the current density was 4.5 A / dm 2 Anodizing treatment was performed under the conditions of 1g / m 2 An anodic oxide film was formed. The average diameter of the micropores in Support 2 was 40 nm. The lightness L* value of the anodized film surface of Support 2 in the L*a*b* color system was 83.7.

[0292] The tensile strength of the obtained support 2 was 188 MPa. The magnesium content in the support 2 was 0.064 mass %.

[0293] <Creating support 3> (Preparation of aluminum alloy 3) Aluminum alloy 3 was produced in the same manner as in the production of aluminum alloy 1-1, except that the magnesium content and rolling reduction were changed as shown in Table 1. (Preparation of Support 3) A support 3 was produced using aluminum alloy 3 according to the support manufacturing method of Example 5 of WO 2021 / 67054. The tensile strength of the obtained support 3 was 188 MPa. The magnesium content in the support 3 was 0.064 mass %.

[0294] <Preparation of Support 4> (Preparation of aluminum alloy 4) Aluminum alloy 4 was produced in the same manner as in the production of aluminum alloy 1-1, except that the magnesium content and rolling reduction were changed as shown in Table 1. (Preparation of Support 4) The above aluminum alloy 4 was subjected to the following treatments (Ja) to (Jm) to produce a support 4. Note that water rinsing treatment was carried out between all treatment steps, and after the water rinsing treatment, the liquid was removed using nip rollers.

[0295] (Ja) Mechanical roughening treatment (brush grain method) Using the apparatus shown in Figure 5, a pumice suspension (specific gravity 1.1 g / cm 3 ) was supplied to the surface of the aluminum plate as an abrasive slurry, while mechanical roughening treatment was performed using a rotating bundled brush. In Fig. 5, 31 is the aluminum plate, 32 and 34 are roller-shaped brushes (bundled brushes in this example), 33 is the abrasive slurry, and 35, 36, 37, and 38 are support rollers. For the mechanical roughening treatment, the median diameter (μm) of the abrasive was 30 μm, the number of brushes was four, and the brush rotation speed (rpm) was 250 rpm. The brush bundles were made of 6·10 nylon, with bristles of 0.3 mm in diameter and 50 mm in length. The brushes were densely packed into holes drilled into a φ300 mm stainless steel cylinder. The distance between the two support rollers (φ200 mm) below the brush bundles was 300 mm. The brush bundles were pressed down until the load on the drive motor rotating the brushes was 10 kW higher than the load before pressing the brush bundles against the aluminum plate. The brush rotation direction was the same as the movement direction of the aluminum plate.

[0296] (Jb) Alkaline etching treatment An aluminum plate was etched by spraying an aqueous solution of caustic soda with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass onto the plate at a temperature of 70°C. The amount of dissolved aluminum on the surface to be subsequently subjected to electrochemical graining treatment was 10 g / m 2 It was.

[0297] (Jc) Desmutting treatment using an acidic aqueous solution The acidic aqueous solution was a waste solution of nitric acid used in the subsequent electrochemical graining treatment, which was at a liquid temperature of 35°C, and sprayed onto the aluminum plate for 3 seconds to perform desmutting.

[0298] (Jd) Electrochemical roughening treatment using aqueous nitric acid solution A continuous electrochemical roughening treatment was carried out using a 60 Hz AC voltage. The electrolyte used was an aqueous solution of nitric acid 10.4 g / L to which aluminum nitrate was added to adjust the aluminum ion concentration to 4.5 g / L, and the solution temperature was 35°C. The AC power waveform was as shown in Figure 1, with a time tp from zero to peak of the current being 0.8 msec, a duty ratio of 1:1, and a trapezoidal square wave AC. Electrochemical roughening treatment was carried out using a carbon electrode as the counter electrode. Ferrite was used as the auxiliary anode. The electrolytic cell used was as shown in Figure 2. The current density was 30 A / dm at the peak current value. 2 5% of the current flowing from the power supply was shunted to the auxiliary anode. 2 ) is the total amount of electricity when the aluminum plate is the anode, 185C / dm 2 It was.

[0299] (Je) Alkaline etching treatment An aluminum plate was etched by spraying an aqueous solution of caustic soda with a caustic soda concentration of 27% by mass and an aluminum ion concentration of 2.5% by mass onto the aluminum plate at a temperature of 50°C. The amount of dissolved aluminum was 3.5 g / m 2 It was.

[0300] (Jf) Desmutting treatment using an acidic aqueous solution The acidic aqueous solution, which had a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L and a liquid temperature of 30° C., was sprayed onto the aluminum plate for 3 seconds to perform desmutting.

[0301] (Jg) Electrochemical roughening treatment using hydrochloric acid solution A continuous electrochemical graining treatment was carried out using a 60 Hz AC voltage. The electrolyte used was an aqueous solution of 6.2 g / L hydrochloric acid with aluminum chloride added to adjust the aluminum ion concentration to 4.5 g / L, and the solution temperature was 35°C. The AC power waveform was as shown in Figure 1, with a time tp from zero to peak of the current being 0.8 msec, a duty ratio of 1:1, and a trapezoidal square wave AC. Electrochemical graining treatment was carried out using a carbon electrode as the counter electrode. Ferrite was used as the auxiliary anode. The electrolytic cell used was as shown in Figure 2. The current density was 25 A / dm at the peak current value. 2 and the amount of electricity in hydrochloric acid electrolysis (C / dm 2 ) is the total amount of electricity when the aluminum plate is the anode, 63C / dm 2 It was.

[0302] (Jh) Alkaline etching treatment An aluminum plate was etched by spraying an aqueous solution of caustic soda containing 5% by mass of caustic soda and 0.5% by mass of aluminum ions onto the aluminum plate at a temperature of 60°C. The amount of dissolved aluminum was 0.2 g / m 2 It was.

[0303] (Ji) Desmutting treatment using an acidic aqueous solution The acidic aqueous solution was an aqueous solution of wastewater (sulfuric acid concentration 170 g / L and aluminum ion concentration 5 g / L) generated in the anodizing process at a liquid temperature of 35°C, which was sprayed onto the aluminum plate for 4 seconds to perform desmutting.

[0304] (Jj) First stage anodizing The first stage of anodizing treatment was carried out using a DC electrolysis anodizing apparatus with the structure shown in Figure 6. A 170 g / L aqueous sulfuric acid solution was used as the electrolyte, and the solution temperature was 50°C and the current density was 30 A / dm 2 Anodizing treatment was performed under the conditions of 0.3 g / m 2 An anodic oxide film was formed.

[0305] (Jk) Porewide processing The anodized aluminum plate was immersed in an aqueous solution of caustic soda with a caustic soda concentration of 5% by mass and an aluminum ion concentration of 0.5% by mass at 40° C. for 3 seconds to perform a pore widening treatment.

[0306] (Jl) Second stage anodizing The second stage of anodizing treatment was carried out using a DC electrolysis anodizing apparatus with the structure shown in Figure 6. A 170 g / L aqueous sulfuric acid solution was used as the electrolyte, and the solution temperature was 50°C and the current density was 13 A / dm 2 Anodizing treatment was performed under the conditions of 2.1 g / m 2 An anodic oxide film was formed.

[0307] (Jm) Hydrophilic treatment To ensure hydrophilicity in non-image areas, the aluminum plate was subjected to silicate treatment by immersing it in a 2.5% by mass aqueous solution of No. 3 sodium silicate at 50°C for 7 seconds. The amount of silicon attached was 8.5 mg / m 2 The average diameter of the micropores was 30 nm. The lightness L* value of the anodized film surface of Support 4 in the L*a*b* color system was 72.3.

[0308] The tensile strength of the obtained support 4 was 200 MPa. The magnesium content in the support 4 was 0.075% by mass.

[0309] <Preparation of Support 5> (Preparation of Aluminum Alloy 5) Aluminum alloy 5 was produced in the same manner as in the production of aluminum alloy 1-1, except that the magnesium content and rolling reduction were changed as shown in Table 1. (Preparation of Support 5) -Alkaline etching treatment- An etching treatment was carried out by spraying an aqueous solution of caustic soda containing 26% by mass of caustic soda and 6.5% by mass of aluminum ions onto the aluminum alloy 5 at a temperature of 55°C. After that, the aluminum alloy was washed with water by spraying. The amount of dissolved aluminum on the surface to be subsequently subjected to electrochemical graining treatment was 3 g / m. 2 It was.

[0310] - Desmutting treatment using an acidic aqueous solution (first desmutting treatment) - Next, a desmutting treatment was carried out using an acidic aqueous solution. The acidic aqueous solution used for the desmutting treatment was an aqueous solution of 170 g / L sulfuric acid. The liquid temperature was 30°C. The acidic aqueous solution was sprayed onto the aluminum plate, and the desmutting treatment was carried out for 3 seconds. After that, a water rinsing treatment was carried out.

[0311] -Electrochemical roughening treatment- Next, electrochemical roughening treatment was carried out using an electrolytic solution of hydrochloric acid and an alternating current. The temperature of the electrolytic solution was 40°C. The waveform of the alternating current was a sine wave with symmetrical positive and negative waveforms, and the frequency was 50Hz. The total amount of electricity that the aluminum plate took part in the anodic reaction was 300C / dm 2 A carbon electrode was used as the counter electrode for the aluminum plate, and then the plate was washed with water.

[0312] -Alkaline etching treatment- After electrochemical graining, an aqueous solution of caustic soda with a caustic soda concentration of 5% by mass and an aluminum ion concentration of 0.5% by mass was sprayed onto the aluminum plate at a temperature of 35°C to etch the plate to an etching depth of 0.1 g / m. 2 The etching treatment was carried out as follows: Then, a water washing treatment was carried out.

[0313] -Desmutting treatment using an acidic aqueous solution- Next, a desmutting treatment was carried out using an acidic aqueous solution. The acidic aqueous solution used for the desmutting treatment was an aqueous solution of 170 g / L sulfuric acid. The liquid temperature was 30°C. The acidic aqueous solution was sprayed onto the aluminum plate, and the desmutting treatment was carried out for 3 seconds. After that, a water rinsing treatment was carried out.

[0314] -Anodizing treatment- Using a direct current in a sulfuric acid solution of 170 g / L at a solution temperature of 40°C, the amount of anodized film is 3 g / m 2 The support 5 was obtained by anodizing. The tensile strength of the obtained support 5 was 188 MPa. The magnesium content in the support 5 was 0.064 mass %.

[0315] <Preparation of Supports 1-1C to 1-2C> Aluminum alloys 1-2 to 1-10 were prepared in the same manner as for Support 1-1, except that in the preparation of Support 1-1, the rolling reduction and magnesium content were changed as shown in Table 1, and Supports 1-1C to 1-2C were prepared. Table 1 shows the tensile strength, rolling reduction, and magnesium content of each support of supports 1-1 to 1-10, 2 to 5, and 1-1C to 1-2C.

[0316] [Table 2]

[0317] <Formation of Undercoat Layer 1> On the support, a coating solution (1) for the undercoat layer having the following composition was applied in a dry coating amount of 0.03 mg / m 2 The undercoat layer 1 was formed by coating the mixture so that the thickness became

[0318] (Undercoat layer coating solution (1)) Polyacrylic acid aqueous solution (40% by mass) Jurymer AC-10S (manufactured by Toagosei Co., Ltd.) 3.0 parts ·Wednesday 27.0 parts

[0319] <Formation of Undercoat Layer 2> On the support, a coating solution (2) for the undercoat layer having the following composition was applied in a dry amount of 26 mg / m 2 The undercoat layer 2 was formed by coating the mixture so that the thickness became

[0320] (Undercoat layer coating solution (2)) Undercoat layer compound (2) (structure below) 0.013 parts Hydroxyethyliminodiacetic acid 0.005 parts Tetrasodium ethylenediaminetetraacetate 0.005 parts Polyoxyethylene lauryl ether 0.0003 parts ·Wednesday 3.15 parts

[0321] [ka]

[0322] The numerical value in the parentheses to the right of each structural unit in the compound (2) for undercoat layer indicates the mass ratio, and the numerical value in the parentheses to the right of the ethyleneoxy unit indicates the number of repetitions.

[0323] <Formation of Image Recording Layer 1> The image recording layer coating solution (1) having the following composition was applied by bar coating and dried in an oven at 110°C for 40 seconds to give a dry weight of 0.9 / m 2 The image recording layer 1 was formed.

[0324] (Image recording layer coating liquid (1)) 39.75 parts 1-propanol 39.85 parts 2-butanone γ-Butyl lactone 0.88 parts Polymer emulsion A *1 6.95 copies ·KLUCEL E *2 0.25 parts Urethane acrylate *3 1.65 copies Sartomer SR399 *4 0.77 parts Iodonium salt A*5 0.15 parts Iodonium salt B *6 0.15 parts Infrared absorber A *7 0.15 parts 3-mercapto-1,2,4-triazole 0.05 parts Black-XV *8 0.15 parts BYK 336 *9 0.18 parts Techpolymer SSX-105 *10 0.47 parts *1: Polymer emulsion A is a dispersion of polymer particles of a graft copolymer of poly(ethylene glycol) methyl ether methacrylate / styrene / acrylonitrile = 10:9:81, which is contained at 24% by mass in a solvent of n-propanol / water with a mass ratio of 80 / 20. The volume average particle size is 193 nm. *2: Klucel E refers to hydroxypropyl cellulose available from Hercules. *3: A polymerizable compound obtained by reacting DESMODUR (registered trademark) N100 with hydroxyethyl acrylate and pentatritol acrylate in a molar ratio of 1:1.5:1.5, at a concentration of 80% by mass in 2-butanone solution. *4: Dipentaerythritol pentaacrylate ester (Sartomer Company) *5: Compound represented by the following formula 1 *6: Compound represented by the following formula 2

[0325] [ka]

[0326] *7: The infrared absorber is the compound represented by A below.

[0327] [ka]

[0328] *8: Black-XV (Yamamoto Kasei Co., Ltd.) *9: Xylene / methoxypropyl acetate solution containing modified polydimethylsiloxane copolymer at a concentration of 25% by mass (BYK Chemie) *10: Cross-linked acrylic beads, average particle size 5.0 μm (Sekisui Plastics Co., Ltd.)

[0329] <Formation of image recording layer 2> The image recording layer coating solution (2) having the following composition was applied by bar coating and dried in an oven at 110°C for 40 seconds to give a dry weight of 0.9 / m 2 The image recording layer 2 was formed.

[0330] (Image recording layer coating liquid (2)) 39.75 parts 1-propanol 39.85 parts 2-butanone γ-Butyl lactone 0.88 parts Polymer emulsion A *1 6.95 copies ·KLUCEL E *2 0.25 parts Urethane acrylate *3 1.65 copies Sartomer SR399 *4 0.77 parts Iodonium salt A *5 0.15 parts Iodonium salt B *6 0.15 parts Infrared absorber B *11 0.15 parts Infrared absorber C *12 0.15 parts 3-mercapto-1,2,4-triazole 0.05 parts Black-XV *8 0.15 parts BYK 336 *9 0.18 parts Techpolymer SSX-105 *10 0.47 parts *1 to *10 are as described above. *11: The infrared absorber is the compound represented by B below. *12: The infrared absorber is the compound represented by C below.

[0331] [ka]

[0332] <Formation of image recording layer 3> The image recording layer coating solution (3) having the following composition was applied by bar coating and dried in an oven at 110°C for 40 seconds to give a dry weight of 0.9 / m 2 The image recording layer 3 was formed.

[0333] (Image recording layer coating liquid (3)) 39.75 parts 1-propanol 39.85 parts 2-butanone γ-Butyl lactone 0.88 parts Polymer emulsion A *1 6.95 copies ·KLUCEL E *2 0.25 parts Urethane acrylate *3 1.65 copies Sartomer SR399 *4 0.77 parts Iodonium salt A *5 0.15 parts Iodonium salt B *6 0.15 parts Infrared absorber A *7 0.15 parts 3-mercapto-1,2,4-triazole 0.05 parts Leuco dye A *12 0.15 parts BYK 336 *9 0.18 parts Techpolymer SSX-105 *10 0.47 parts *1 to *10 are as described above. *12: Leuco dye A is a compound represented by the following structure.

[0334] [ka]

[0335] <Formation of Image Recording Layer 4> An image recording layer coating solution (4) having the following composition was applied by bar coating and dried in an oven at 100° C. for 60 seconds to form an image recording layer 4 having a thickness of 1.2 μm. The image recording layer coating solution (4) was obtained by mixing and stirring the following photosensitive solution (1) and microgel solution (1) immediately before coating.

[0336] (Photosensitive liquid (1)) Binder polymer (6) 23% by mass 1-methoxy-2-propanol solution (structure below) 0.2891 copies Binder polymer (7) 23% by mass 1-methoxy-2-propanol solution (structure below) 0.4574 copies Infrared absorber (1) (structure below) 0.0278 parts Borate compounds (1) (sodium tetraphenylborate) 0.015 parts Polymerization initiator (1) (structure below) 0.2348 parts Polymerizable compound (1) (tris(acryloyloxyethyl) isocyanurate, NK Ester A-9300 40% 2-butanone solution, manufactured by Shin-Nakamura Chemical Co., Ltd.) 0.2875 copies Low molecular weight hydrophilic compound (1) (tris(2-hydroxyethyl) isocyanurate) 0.0287 parts Low molecular weight hydrophilic compound (2) (trimethylglycine) 0.0147 parts Anionic surfactant 1 30% by weight aqueous solution (structure below) 0.25 parts Ultraviolet absorber (1) (TINUVIN 405, manufactured by BASF Ltd.) (structure shown below) 0.04 parts Fluorine-based surfactant (1) (structure below) 0.004 parts Phosphonium compound (1) (structure below) 0.020 parts 5.346 parts 2-butanone 3.128 parts 1-methoxy-2-propanol Methanol 0.964 parts ·Pure water 0.036 parts

[0337] (Microgel liquid (1)) ·Microgel (1) (solid content 21.8% by mass) 2.243 parts 0.600 parts 1-methoxy-2-propanol

[0338] (Preparation of Microgel (1)) The method for preparing the microgel (1) used in the above microgel solution is described below.

[0339] <Preparation of polyisocyanate compound (1)> To a suspension of 17.78 parts (80 molar equivalents) of isophorone diisocyanate and 7.35 parts (20 molar equivalents) of the following polyhydric phenol compound (1) in ethyl acetate (25.31 parts), 0.043 parts of bismuth tris(2-ethylhexanoate) (Neostan U-600, manufactured by Nitto Kasei Co., Ltd.) was added and stirred. Once the heat generation subsided, the reaction temperature was set to 50°C, and the mixture was stirred for 3 hours to obtain an ethyl acetate solution (50% by mass) of the polyhydric isocyanate compound (1).

[0340] [ka]

[0341] <Preparation of Microgel (1)> The oil phase and aqueous phase components listed below were mixed and emulsified using a homogenizer at 12,000 rpm for 10 minutes. The resulting emulsion was stirred at 45°C for 4 hours, after which 5.20 parts of a 10% by weight aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene-octylate (U-CAT SA102, manufactured by San-Apro Co., Ltd.) was added. The mixture was stirred at room temperature for 30 minutes and then allowed to stand at 45°C for 24 hours. The solids concentration was adjusted to 21.8% by weight with distilled water to obtain an aqueous dispersion of microgel (4). The volume average particle size was measured by light scattering using a dynamic light scattering particle size distribution analyzer LB-500 (manufactured by Horiba, Ltd.) and found to be 0.28 μm.

[0342] (oil phase component) (Component 1) Ethyl acetate 12.0 parts (Component 2) An adduct (50% by mass ethyl acetate solution, manufactured by Mitsui Chemicals, Inc.) obtained by adding trimethylolpropane (6 moles) and xylene diisocyanate (18 moles) to which was added polyoxyethylene (1 mole, number of repeating oxyethylene units: 90) terminated with a methyl group. 3.76 copies (Component 3) Polyisocyanate compound (1) (as a 50% by mass solution in ethyl acetate) 15.0 copies (Component 4) 11.54 parts of a 65% by weight solution of dipentaerythritol pentaacrylate (SR-399, manufactured by Sartomer Corporation) in ethyl acetate (Component 5) 4.42 parts of a 10% ethyl acetate solution of sulfonate surfactant (Paionin A-41-C, manufactured by Takemoto Oil & Fat Co., Ltd.)

[0343] (Aqueous phase component) 46.87 parts distilled water

[0344] <Synthesis of binder polymer (6)> 78.0 g of 1-methoxy-2-propanol was weighed into a three-neck flask and heated to 70°C under a nitrogen stream. A mixed solution consisting of 52.1 g of Blemmer PME-100 (methoxydiethylene glycol monomethacrylate, manufactured by Nippon Oil & Fats Corporation), 21.8 g of methyl methacrylate, 14.2 g of methacrylic acid, 2.15 g of hexakis(3-mercaptopropionic acid)dipentaerythritol, 0.38 g of V-601 (2,2'-azobis(isobutyrate)dimethyl, manufactured by Wako Pure Chemical Industries, Ltd.), and 54 g of 1-methoxy-2-propanol was added dropwise to this reaction vessel over 2 hours and 30 minutes. After completion of the dropwise addition, the temperature was raised to 80°C, and the reaction was continued for another 2 hours. A mixed solution consisting of 0.04 g of V-601 and 4 g of 1-methoxy-2-propanol was added, and the temperature was raised to 90° C., followed by reaction for 2.5 hours. After completion of the reaction, the reaction solution was cooled to room temperature. To the above reaction solution, 137.2 g of 1-methoxy-2-propanol, 0.24 g of 4-hydroxytetramethylpiperidine-N-oxide, 26.0 g of glycidyl methacrylate, and 3.0 g of tetraethylammonium bromide were added and stirred thoroughly, followed by heating at 90°C. After 18 hours, the reaction solution was cooled to room temperature (25°C) and then diluted with 99.4 g of 1-methoxy-2-propanol. The binder polymer (6) thus obtained had a solid content concentration of 23% by mass and a polystyrene-equivalent weight average molecular weight of 35,000 as measured by GPC.

[0345] [ka]

[0346] <Synthesis of binder polymer (7)> 78.00 g of 1-methoxy-2-propanol was weighed into a three-neck flask and heated to 70°C under a nitrogen stream. A mixed solution consisting of 52.8 g of Blemmer PME-100 (methoxydiethylene glycol monomethacrylate, manufactured by Nippon Oil & Fats Corporation), 2.8 g of methyl methacrylate, 25.0 g of methacrylic acid, 6.4 g of hexakis(3-mercaptopropionic acid)dipentaerythritol, 1.1 g of V-601 (2,2'-azobis(isobutyric acid)dimethyl, manufactured by Wako Pure Chemical Industries, Ltd.), and 55 g of 1-methoxy-2-propanol was added dropwise to the reaction vessel over 2 hours and 30 minutes. After the addition was completed, the temperature was raised to 80°C, and the reaction was continued for another 2 hours. After 2 hours, a mixed solution consisting of 0.11 g of V-601 and 1 g of 1-methoxy-2-propanol was added, and the temperature was raised to 90° C., followed by reaction for 2.5 hours. After completion of the reaction, the reaction solution was cooled to room temperature. To the above reaction solution, 177.2 g of 1-methoxy-2-propanol, 0.28 g of 4-hydroxytetramethylpiperidine-N-oxide, 46.0 g of glycidyl methacrylate, and 3.4 g of tetrabutylammonium bromide were added and stirred thoroughly, followed by heating at 90°C. After 18 hours, the reaction solution was cooled to room temperature (25°C), and then diluted with 0.06 g of 4-methoxyphenol and 114.5 g of 1-methoxy-2-propanol. The binder polymer (7) thus obtained had a solid content concentration of 23% by mass and a weight average molecular weight of 15,000 in terms of polystyrene measured by GPC.

[0347] [ka]

[0348] [ka]

[0349] [ka]

[0350] <Formation of Image Recording Layer 5> The image recording layer coating solution (5) having the following composition was applied by bar coating and dried in an oven at 120°C for 40 seconds to give a dry weight of 1.0 / m 2 The image recording layer 5 was formed.

[0351] The image recording layer coating solution (5) contained the components described below and was prepared using a mixed solvent of 1-methoxy-2-propanol (MFG):methyl ethyl ketone (MEK):methanol = 4:4:1 (mass ratio) so that the solid content was 6 mass %. Electron-accepting polymerization initiator Int-1 0.06 parts Infrared absorber IR-1 0.026 parts Electron-donating polymerization initiator B-1 0.050 parts ·Polymerizable compound M-1 0.25 part ·Polymerizable compound M-2 0.25 part Binder polymer P-2 0.15 parts Acid color former S-3 0.03 parts ·Hydrophilic compound T-2 0.01 part

[0352] P-2: Polyvinyl acetal, S-LEC BL10 manufactured by Sekisui Chemical Co., Ltd.

[0353] [ka]

[0354] The image recording layers 1 to 5 are uniformly dispersed in water at 20° C. The image recording layers 1 to 5 are water-dispersible.

[0355] <Formation of protective layer 1> After applying a protective layer coating solution (1) having the following composition to the substrate with a bar, the substrate was dried in an oven at 120°C for 60 seconds to obtain a dry coating amount of 0.15 g / m 2 A protective layer of

[0356] (Protective layer coating solution (1)) Inorganic layered compound dispersion (1) (see below): 1.5 parts Hydrophilic polymer (1) (structure shown below, Mw: 30,000) (solid content): 0.03 parts 0.10 parts of a 6% by weight aqueous solution of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., CKS50, sulfonic acid modified, saponification degree 99 mol% or more, polymerization degree 300) 0.03 parts of a 6% by weight aqueous solution of polyvinyl alcohol (PVA-405, manufactured by Kuraray Co., Ltd., saponification degree 81.5 mol%, polymerization degree 500) 0.86 parts of surfactant (Emalex 710, manufactured by Nippon Emulsion Co., Ltd., structure shown below) 1% by weight aqueous solution Ion-exchanged water: 6.0 parts

[0357] [ka]

[0358] (Preparation of Inorganic Layered Compound Dispersion (1)) 6.4 parts of synthetic mica Somasif ME-100 (manufactured by Co-op Chemical Co., Ltd.) was added to 193.6 parts of ion-exchanged water, and the mixture was dispersed using a homogenizer until the volume average particle size (laser scattering method) reached 3 μm. The aspect ratio of the resulting dispersed particles was 100 or more.

[0359] <Formation of protective layer 2> The protective layer coating solution (2) having the following composition was applied with a bar and dried in an oven at 120°C for 60 seconds to obtain a dry coating amount of 0.15 g / m 2 A protective layer 2 was formed. The protective layer coating solution (2) contained the components described below and was prepared with ion-exchanged water so that the solid content was 6% by mass. Discoloring compound A 0.02 parts Hydrophilic polymer WP-1 0.70 parts Hydrophilic polymer WP-2 0.20 parts Hydrophilic polymer WP-3 0.20 parts Surfactant 0.002 parts

[0360] WP-1: Polyvinyl alcohol, Mowiol 4-88 manufactured by Sigma-Aldrich WP-2: Polyvinyl alcohol, Mowiol 8-88 manufactured by Sigma-Aldrich WP-3: The following resin (Mw 52,000) Surfactant: Anionic surfactant, Rapisol A-80, manufactured by NOF Corporation

[0361] [ka]

[0362] <Formation of Backcoat Layers 1 to 9> Each of the backcoat layer coating solutions (backcoat layer coating solutions (1) to (9)) having the following compositions was applied with a bar to the side of the support opposite to the side having the image recording layer, and dried at 100°C for 30 seconds to form backcoat layers 1 to 9 each having a thickness of 1.1 μm.

[0363] (Backcoat layer coating liquid) Binder (listed in Table 2) 11.072 parts Matte particles (listed in Table 2) 0.975 parts Fluorosurfactant (1) 0.250 parts 74.123 parts 2-butanone 8.720 parts 1-methoxy-2-propanol Methanol 4.360 parts

[0364] [ka]

[0365] [Table 3]

[0366] <Formation of Backcoat Layer 10> On the side of the support opposite to the side having the image recording layer, the backcoat layer coating solution (10) having the above composition was bar-coated using a bar coater in accordance with the method described in paragraph

[0336] of WO 2017 / 170391 so that the arithmetic mean height Sa of the backcoat layer was in the range of 0.51 μm, to form a backcoat layer 10 having a thickness of 1.1 μm.

[0367] (Backcoat layer coating solution (10)) Epoxy resin (JER1009: Japan Epoxy Resin Co., Ltd.) 0.80 copies Fluorosurfactant (Megafac F-780-F: Dainippon Ink and Chemicals Co., Ltd.) 0.005 parts Methyl ethyl ketone (MEK) 22.5 parts 2.5 parts 1-methoxy-propanol

[0368] <Formation of backcoat layer 11> On the side of the support opposite to the side having the image recording layer, the backcoat layer coating solution (10) having the above composition was applied in a solid manner in accordance with the method described in paragraph

[0339] of WO 2017 / 170391 to form a flat thin film portion, and then a thick film portion was applied thereon using a spray coating device, followed by drying to form a backcoat layer 11 having a thickness of 1.1 μm. The thickness of each backcoat layer is the average thickness (T), which was measured as described above.

[0369] [Preparation of lithographic printing plate precursor] The above supports, undercoat layers, image recording layers, protective layers, and backcoat layers were combined as shown in Table 3 to prepare lithographic printing plate precursors of Examples 1 to 31 and Comparative Examples 1 to 3. The static friction coefficient between the surface of the outermost layer on the side opposite to the side having the image recording layer and the metal SUS316 is shown in Table 3. The static friction coefficient was measured as follows. <Measurement of static friction coefficient> The static friction coefficient was measured according to the method described in JIS P8147. Specifically, using a static friction coefficient measuring instrument TYPE:10 manufactured by Shinto Scientific Co., Ltd., the static friction coefficient between the outermost layer surface on the side opposite the image recording layer and the metal SUS316 was measured three times, and the average value of these measurements was taken as the static friction coefficient. The measurement was carried out in a thermostatic chamber maintained at a temperature of 25°C and a humidity of 50%.

[0370] The arithmetic mean height Sa of the outermost layer surface on the side opposite to the side having the image recording layer is shown in Table 3. The arithmetic mean height Sa was measured as follows. <Measurement of arithmetic mean height Sa> The arithmetic mean height Sa was measured according to the method described in ISO 25178. That is, three or more locations were selected from the same sample and measured using a Micromap MM3200-M100 manufactured by Ryoka Systems Co., Ltd., and the average value of these measurements was taken as the arithmetic mean height Sa. The measurement range was a 400 μm × 400 μm area randomly selected from the sample surface.

[0371] The average thickness (T) of the backcoat layer is listed in Table 3 as a thickness. The average thickness (T) of the backcoat layer was measured as described above. The average particle size of the particles is the volume average particle size and was measured as described above. The surface free energy of the outermost layer surface on the side opposite to the side having the image recording layer is shown in Table 3. The surface free energy was measured as follows.

[0372] <Measurement of surface free energy> The surface free energy was calculated from the contact angles with pure water and iodomethane using the Owens-Wedent theory. Specifically, the contact angles with pure water and iodomethane were measured on the side opposite to the image recording layer, and γsv was calculated by solving the following linear equation with two unknowns: d and γsv h The sum of these was taken as the surface energy γs.

[0373]

number

[0374] γsv d : Surface free energy dispersion term of the measurement surface γsv h : Surface free energy hydrogen bond term of the measurement surface γLv d : Surface free energy dispersion term of the dropping liquid γLv h : Hydrogen bond term of the surface free energy of the dropping liquid θ: Contact angle 2 seconds after dropping γL=γLv d +γLv h

[0375] [Table 4]

[0376] [Table 5]

[0377] <Evaluation of misregistration> The lithographic printing plate precursors of Examples 1 to 31 and Comparative Examples 1 to 3 were exposed using a Luxcel PLATESETTER T-6000III equipped with an infrared semiconductor laser manufactured by Fujifilm Corporation under the conditions of an outer drum rotation speed of 1,000 rpm, a laser output of 70%, and a resolution of 2,400 dpi. A chart including register marks was used as the exposed image. The image-exposed lithographic printing plate precursor was mounted on a Tokyo Kikai Seisakusho offset rotary press, and printing was performed on newsprint at a speed of 100,000 sheets per hour using Toyo Ink's Vente Unecho Ink N as the newspaper printing ink and a 1% by weight mixture of alkane as the dampening solution. After printing 300 sheets, the press was stopped, and the distance from the leading edge of the plate to the center of the register mark on the paper was measured and recorded as [L1]. After printing 100,000 sheets, the distance from the leading edge of the plate to the center of the register mark on the paper was measured and recorded as [L2]. The plate misalignment amount ΔL was calculated using the following formula (1), and a 5-point rating was given based on the calculated value. △L=L2-L1 (1)

[0378] 5 points: Absolute value of △L is less than 50 μm 4 points: Absolute value of △L is 50 μm or more and less than 100 μm 3 points: Absolute value of △L is 100 μm or more and less than 150 μm 2 points: Absolute value of △L is 150 μm or more and less than 200 μm 1 point: Absolute value of △L is 200 μm or more

[0379] <Cutting the lithographic printing plate precursor> The planographic printing plate precursors of Examples 1 to 31 were cut using a rotary blade as shown in FIG. 4, with the gap between the upper and lower cutting blades, the amount of engagement, and the blade edge angle adjusted to form sagging shapes at the edges. The sagging amount X and sagging width Y of the sagging shape are shown in Table 3.

[0380] <Formation of edge layer 1> Composition 1 was applied under the following application conditions 1 to form edge layer 1.

[0381] (Application condition 1) Coating was carried out using the coating method shown in Figure 7. The wire bar was positioned so that it was perpendicular (θ=0°) to the lithographic printing plate precursor, and coating was carried out using the following procedure. [1] HN-GV (manufactured by Fujifilm Global Graphics Systems Co., Ltd.) is used on a No. 10 wire bar, and the wire is evenly distributed 1 cm apart. 3 It dripped. [2] The wire bar was moved at 20 mm / s along the side of the lithographic printing plate precursor, and was positioned so that it was perpendicular (θ=0°) to the lithographic printing plate precursor. [3] Drying was performed by blowing air at 80°C and 6 m / s for 30 seconds. [4] Composition 1 could be applied only to the side of the lithographic printing plate precursor. At this time, the coating amount of Composition 1 was 120 mg / m 2 It was. [5] The variation Z in the coating width from the edge of the lithographic printing plate precursor was Z=0.1 mm.

[0382] Composition 1 contains the following components: 75.00 parts deionized water Penon JE66 *1 12.95 copies NISSAN ANON BDF-SF *2 9.50 copies 2.50 parts sodium hexametaphosphate Bioden ZNS *3 0.05 part

[0383] *1: Etherified starch (Nippon Starch Chemical Co., Ltd.) *2: Cocamidopropyl betaine (NOF Corporation) *3: Disinfectant or biocide (Daiwa Chemical Industries Corporation)

[0384] The above-mentioned variation Z is calculated based on

[0186] to

[0187] of Patent No. 6628949.

[0385] A lithographic printing plate precursor having a sagging shape at the edge and an edge layer were combined as shown in Table 3 to prepare a lithographic printing plate precursor for measuring edge stain prevention properties. The edge stain resistance was evaluated as follows.

[0386] <Prevents edge staining> The resulting lithographic printing plate precursor was exposed using a Luxcel PLATESETTER T-6000III infrared semiconductor laser (manufactured by Fujifilm Corporation) at an outer drum rotation speed of 1,000 rpm, a laser output of 70%, and a resolution of 2,400 dpi. The exposed image used was a chart containing a solid image, a 50% halftone dot image, and a non-image area. The image-exposed lithographic printing plate precursor was mounted on a Tokyo Kikai Seisakusho offset web press, and printing was performed on newsprint at a speed of 100,000 sheets per hour using Inktec Corporation's Soybee KKST-S (Red) newspaper ink and Toyo Ink Co., Ltd.'s Toyo ALKY dampening solution. The 1,000th print was sampled at a water level 1.1 times the water level required for eliminating background scumming, and the degree of linear scumming caused by the edges of the lithographic printing plate precursor was evaluated according to the following criteria. The results are shown in Table 3 as edge scum resistance. 5: Not dirty at all 4: Intermediate level between 5 and 3 3: Slightly dirty but acceptable 2: Intermediate level between 3 and 1 (acceptable level) 1: Clearly dirty and unacceptable

[0387] From the results shown in Table 3, the on-press developable lithographic printing plate precursor of the present invention, which has a tensile strength of 160 MPa or more and has the specified characteristics on the outermost layer surface opposite the side having the image recording layer, can suppress plate misalignment of the lithographic printing plate during printing with the lithographic printing plate. It is also apparent that the use of a lithographic printing plate precursor having a predetermined sagging shape results in excellent edge stain resistance. [Explanation of symbols]

[0388] 1 Planographic printing plate original plate 1a Image recording layer surface 1b Support surface 1c end face 2 Sauce 10 cutting blade 10a Upper cutting blade 10b Upper cutting blade 11 Rotation axis 20 cutting blade 20a Lower cutting blade 20b Lower cutting blade 21 Rotation axis 30 Planographic printing plate original plate 31 Aluminum plate 32, 34 Roller brush 33 Polishing slurry 35, 36, 37, 38 Support rollers 50 Main electrolyzer 51 AC power supply 52 Radial drum roller 53a, 53b Main pole 54 Electrolyte supply port 55 Electrolyte 56 Slit 57 Electrolyte passage 58 Auxiliary anode 60 Auxiliary anode tank 410 Anodizing treatment equipment 412 Power tank 414 Electrolytic treatment tank 416 Aluminum Plate 418, 426 Electrolyte 420 Power supply electrode 422,428 Laura 424 Nip Roller 430 Electrolytic electrode 432 Tank wall 434 DC power supply B. Boundary between the image recording layer surface and the support W Aluminum Plate X Droop amount Y sag width 100a Lithographic printing plate original plate 120 End face 122 The outermost layer surface 122 on the image recording layer side with respect to the support 138 Wire Bar θ angle

Claims

1. an image recording layer on a support, The support has a tensile strength of 160 MPa or more, An on-press development type lithographic printing plate precursor, wherein the static friction coefficient between the surface of the outermost layer on the side opposite to the side having the image recording layer and metal SUS316 is 0.50 or less.

2. The on-press development type lithographic printing plate precursor according to claim 1 , wherein the support is an aluminum support, and the aluminum support contains 0.020% by mass or more of magnesium.

3. 2. The on-press development type lithographic printing plate precursor according to claim 1, wherein the support is an aluminum support, and the aluminum support is an aluminum plate that has been heat-treated at 250°C or higher in a rolling step and then cold-rolled at a rolling reduction of 80% or higher.

4. an image recording layer on a support, The support has a tensile strength of 160 MPa or more, The on-press development type lithographic printing plate precursor has an arithmetic mean height Sa of the outermost layer surface on the side opposite to the side having the image recording layer of 0.3 μm or more and 20.0 μm or less.

5. The on-press development type lithographic printing plate precursor according to claim 4, which has a backcoat layer on the side opposite to the side having the image recording layer.

6. the backcoat layer contains particles, The on-press development type lithographic printing plate precursor according to claim 5, wherein the average thickness T [μm] of the backcoat layer and the average particle diameter D [μm] of the particles satisfy the following formula (1): D>T...Formula (1)

7. The on-press development type lithographic printing plate precursor according to claim 5 , wherein the backcoat layer has a thin film portion and a thick film portion.

8. an image recording layer on a support, The support has a tensile strength of 160 MPa or more, The surface free energy of the outermost layer surface on the side opposite to the side having the image recording layer is 60 mJ / m ２ The on-press development type lithographic printing plate precursor is as follows.

9. the support has an anodized coating, The on-press development type lithographic printing plate precursor according to any one of claims 1 to 8, wherein the micropores in the anodized film are composed of large-diameter pores extending from the surface of the anodized film to a depth of 10 nm to 1,000 nm and small-diameter pores that communicate with the bottoms of the large-diameter pores and extend from the communicating positions to a depth of 20 nm to 2,000 nm, the large-diameter pores having an average diameter of 15 nm to 100 nm at the surface of the anodized film and the small-diameter pores having an average diameter of less than 15 nm at the communicating positions.

10. the support has an anodized coating, 9. The on-press development type lithographic printing plate precursor according to claim 1, wherein the micropores in the anodized film are composed of small-diameter pores extending from the surface of the anodized film to a depth of 10 nm to 1,000 nm and large-diameter pores that communicate with the bottoms of the small-diameter pores and extend from the communicating positions to a depth of 20 nm to 2,000 nm, and the small-diameter pores have an average diameter of 35 nm or less at the surface of the anodized film, and the large-diameter pores have an average diameter of 40 to 300 nm.

11. the support has an anodized coating, The anodized film is formed by, in order from the surface of the anodized film in the depth direction, an upper layer having a thickness of 30 to 500 nm and having micropores with an average diameter of 20 to 100 nm; an intermediate layer having a thickness of 100 to 300 nm and having micropores with an average diameter that is 1 / 2 to 5 times the average diameter of the micropores in the upper micropore layer; and A lower layer having a thickness of 300 to 2000 nm and having micropores with an average diameter of 15 nm or less. The on-press development type lithographic printing plate precursor according to any one of claims 1 to 8, which comprises

12. The on-press development type lithographic printing plate precursor according to any one of claims 1 to 11, wherein the image recording layer contains an infrared absorber, a polymerization initiator, a polymerizable compound, and a polymer compound.

13. The on-press development type lithographic printing plate precursor according to any one of claims 1 to 12, wherein the image recording layer contains a color former.

14. The on-press development type lithographic printing plate precursor according to any one of claims 1 to 13, wherein the image recording layer is water-soluble or water-dispersible.

15. The on-press development type lithographic printing plate precursor according to any one of claims 12 to 14, wherein the polymer compound is in the form of particles.

16. the particulate polymer compound has a hydrophobic main chain, i) a building block having a pendant cyano group attached directly to the hydrophobic backbone; and ii) a constitutional unit having a pendant group comprising a hydrophilic poly(alkylene oxide) segment; The on-press developable lithographic printing plate precursor according to claim 15, comprising both of the above.

17. 16. The on-press development type lithographic printing plate precursor according to claim 15, wherein the particulate polymer compound is obtained by reacting a polyisocyanate compound, which is an adduct of a polyhydric phenol compound having two or more hydroxy groups in the molecule and isophorone diisocyanate, with a compound having active hydrogen.

18. The on-press development type lithographic printing plate precursor according to any one of claims 1 to 17, wherein an edge of the lithographic printing plate precursor has a sagging shape with a sagging amount X of 25 to 150 µm and a sagging width Y of 70 to 300 µm.

19. The on-press development type lithographic printing plate precursor according to claim 18, wherein the lithographic printing plate precursor has an ink repellent agent on a part or all of two opposing side surfaces thereof.

20. The on-press development type lithographic printing plate precursor according to any one of claims 1 to 19, wherein the arithmetic mean height Sa of the outermost layer surface on the side having the image recording layer is 0.3 µm or more and 20.0 µm or less.

21. 21. A method for preparing a printing plate, comprising: a step of imagewise exposing the on-press development type lithographic printing plate precursor according to any one of claims 1 to 20; and a step of supplying at least one of printing ink and fountain solution on a printing press to remove unexposed areas of an image recording layer in the on-press development type lithographic printing plate precursor.

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