Lithographic printing plate precursors, methods of use and manufacture

Abstract

An on-press developable negative working infrared radiation sensitive lithographic printing plate precursor has an aluminum-containing substrate having at least an aluminum oxide inner layer and an aluminum oxide outer layer. The hydrophilic layer is present on the alumina outer layer and contains a phosphorus-containing compound represented by formula (I) at a coverage of 50-300 mg / m2. A hydrophilic polymer may also be present at a lower coverage than the phosphorus-containing compound. These precursors have an on-machine developable negative-working infrared radiation sensitive imageable layer having at least a radically polymerizable component; an initiator composition that provides radicals upon exposure to imaging infrared radiation; an infrared radiation absorber having an anionic chromophore; and, optionally, a polymeric binder that is different from all other components. Such precursors may be imaged and developed on-press to provide lithographic printing plates, and may be readily prepared using a particular sequence of steps including multiple anodizing steps. # imgabs0 #

Description

Field of the Invention

[0001] The present invention relates to on-press developable negative-working infrared radiation-sensitive lithographic printing plate precursors ("precursors") comprising an inventive aluminum-containing substrate prepared using at least two separate anodizing treatments to provide at least an inner layer of aluminum oxide and an outer layer of aluminum oxide. The aluminum-containing substrate also has a unique hydrophilic layer disposed on the outer layer of aluminum oxide, the hydrophilic layer comprising a predominantly dry coverage of a phosphorus-containing compound at a specific dry coverage. The present invention also relates to methods for infrared radiation imaging and processing of such precursors to provide lithographic printing plates. It further relates to methods of preparing such inventive precursors from inventive aluminum-containing substrates. Background of the Invention

[0003] In lithography, lithographic ink receiving areas, called image areas, are created on the hydrophilic surface of the substrate. When the printing plate surface is moistened with water and a lithographic ink is applied, the hydrophilic areas retain the water and repel the lithographic ink, and the lithographic ink receptive image areas accept the lithographic ink and repel the water. The lithographic ink is transferred from the lithographic printing plate to the surface of the material on which the image is to be reproduced, perhaps using a blanket roller.

[0004] The imageable element or lithographic printing plate precursor used to prepare the lithographic printing plate generally comprises one or more radiation-sensitive imageable layers disposed on the outermost hydrophilic surface of the substrate. After imaging, the exposed (imaged) areas or unexposed (unimaged) areas of the one or more radiation-sensitive layers can be removed using a suitable developer to reveal the outermost hydrophilic surface of the substrate. If the exposed areas are removable, the lithographic printing plate precursor is considered positive-working. Conversely, if the unexposed areas are removable, the lithographic printing plate precursor is considered negative-working.

[0005] The radiation-sensitive photopolymerizable compositions used in negative-working lithographic printing plate precursors generally comprise a free-radically polymerizable component, one or more radiation absorbers, an initiator composition, and optionally one or more polymeric binders different from the other indicated components.

[0006] In recent decades, the industry has emphasized simplifying the lithographic printing plate preparation process, including omitting the pre-development heating step (preheating) and performing on-press development (DOP) with lithographic inks and / or fountain solutions to remove unwanted (unexposed) imageable layer materials on the lithographic printing plate precursor. Such negative-working lithographic printing plate precursors should be designed by balancing many features within the element structure in order to achieve the best industry-required properties of plate run, on-press developability, imaging speed, storage stability, and scratch resistance, among others. Optimizing all of these properties simultaneously is not an easy task, as chemical composition or structural features that provide optimal levels of one or two properties may result in the loss of another property.

[0007] The unique anodized substrates described in U.S. Patent Application Publication 2018 / 0250925 (Merka et al.) provide an advance in the art for on-press developable lithographic printing plate precursors.

[0008] There remains a need to reduce the adverse effects of atmospheric ozone on the imaging chemistry in precursors. Ozone can reduce the imaging sensitivity of certain infrared radiation absorbers (i.e., those containing cationic chromophores with a net positive charge). Precursors with such compounds can exhibit reduced print durability. To truly address this problem, researchers have learned that it is useful to use infrared radiation absorbers containing anionic chromophores with a net negative charge or acidic groups in the imaging chemistry of the imageable layer.

[0009] However, the use of such "anionic" infrared radiation absorbers raises another problem when applying an imaging layer to an aluminum-containing substrate having multiple aluminum oxide layers that has been prepared using sulfuric acid in the final anodizing process as described in U.S. Patent Application Publication 2018 / 0250925 (Merka et al.). Such anodizing processes can generate aluminum sulfate, which is water-soluble, can migrate into the imageable layer and form aluminum salts with the anionic infrared radiation absorbers. This action severely impairs the imaging sensitivity of those infrared radiation absorbers.

[0010] Therefore, there is a need to address these multiple issues without sacrificing imaging sensitivity and print durability. SUMMARY OF THE INVENTION

[0012] The present invention provides a lithographic printing plate precursor comprising:

[0013] an aluminum-containing substrate having a hydrophilic surface, and

[0014] a negative-working, infrared radiation-sensitive imageable layer disposed on a hydrophilic surface of an aluminum-containing substrate,

[0015] The aluminum-containing substrates include:

[0016] an aluminum-containing plate having a ground and etched surface;

[0017] An inner layer of aluminum oxide is disposed on the grained and etched surface, the inner layer of aluminum oxide having an average dry thickness (T i ), and contains many average inner pore diameters (D i ) inner micropores less than or equal to 11 nm, wherein the inner layer of aluminum oxide comprises aluminum sulfate;

[0018] The outer aluminum oxide layer is disposed on the inner aluminum oxide layer, and the outer aluminum oxide layer comprises a plurality of pores having an average outer diameter (D o) of at least 12 nm and up to and including 50 nm of outer micropores, and having an average dry thickness (T of at least 20 nm and up to and including 650 nm) o );and

[0019] A hydrophilic layer disposed on the outer layer of aluminum oxide, wherein the hydrophilic layer comprises: (1) one or more phosphorus-containing compounds having a C1 dry coverage and represented by the following formula (I):

[0020]

[0021] wherein n is 0 or an integer from 1 to 10, and -OM represents -OH or -OM + , and M + is a monovalent cation; and optionally (2) one or more hydrophilic polymers, which when present have a C2 dry coverage,

[0022] Where (1) the C1 dry coverage of one or more phosphorus-containing compounds is at least 50 mg / m 2 Up to and including 300 mg / m 2 , and when (2) one or more hydrophilic polymers are present, the ratio of C1 dry coverage to C2 dry coverage is at least 11:9; and

[0023] The on-press developable negative-working infrared radiation-sensitive imageable layer comprises the following components (a) to (c) and optionally component (d):

[0024] (a) one or more free radical polymerizable components;

[0025] (b) an initiator composition that provides free radicals when the on-press developable negative-working infrared radiation-sensitive imageable layer is exposed to image-wise infrared radiation;

[0026] (c) one or more infrared radiation absorbers comprising an anionic chromophore having a net negative charge or an acidic group; and optionally

[0027] (d) one or more polymeric binders, all of which are different from all of components (a), (b) and (c).

[0028] The present invention also provides a method for providing a lithographic printing plate, comprising:

[0029] exposing a lithographic printing plate precursor of any precursor embodiment of the invention imagewise to imagewise infrared radiation to form an imageable layer having exposed areas and unexposed areas exposed to the infrared radiation, and

[0030] The unexposed areas are removed on-press from the imageable layer imagewise exposed to infrared radiation using a lithographic ink, a fountain solution, or both a lithographic ink and a fountain solution to form a lithographic printing plate.

[0031] Furthermore, the present invention provides a method for preparing a lithographic printing plate precursor, comprising, in sequence:

[0032] A) providing an aluminum-containing plate having an electrochemically or mechanically grained and etched surface;

[0033] B) applying a first anodizing treatment to the aluminum-containing plate to form an aluminum oxide outer layer on the electrochemically or mechanically grained and etched surface, the aluminum oxide outer layer comprising a plurality of average outer micropores having a diameter (D o ) of at least 12 nm and up to and including 50 nm of outer micropores, and having an average dry thickness (T of at least 20 nm and up to and including 650 nm) o );

[0034] C) rinsing the outer layer of aluminum oxide;

[0035] D) subjecting the aluminum-containing plate to an additional anodizing treatment using sulfuric acid to form an inner aluminum oxide layer beneath the outer aluminum oxide layer, the inner aluminum oxide layer having an average dry thickness (T i ), and contains many average inner pore diameters (D i ) inner micropores less than or equal to 11 nm, wherein the inner layer of aluminum oxide comprises aluminum sulfate;

[0036] E) rinsing the outer aluminum oxide layer and the inner aluminum oxide layer;

[0037] F) providing a hydrophilic layer over the outer layer of aluminum oxide, wherein the hydrophilic layer comprises: (1) one or more phosphorus-containing compounds having a C1 dry coverage and represented by the following formula (I):

[0038]

[0039] wherein n is 0 or an integer from 1 to 10, and -OM represents -OH or -OM + , and M + is a monovalent cation; and optionally (2) one or more hydrophilic polymers, which when present have a C2 dry coverage,

[0040] Where (1) the C1 dry coverage of one or more phosphorus-containing compounds is at least 50 mg / m 2 Up to and including 300 mg / m 2 , and when (2) one or more hydrophilic polymers are present, the ratio of C1 dry coverage to C2 dry coverage is at least 11:9; and

[0041] G) forming a negative-working infrared radiation-sensitive imageable layer that can be developed on-press over the outer aluminum oxide layer,

[0042] wherein the on-press developable negative-working infrared radiation-sensitive imageable layer comprises the following components (a) to (c) and optionally component (d):

[0043] (a) one or more free radical polymerizable components;

[0044] (b) an initiator composition that provides free radicals when the on-press developable negative-working infrared radiation-sensitive imageable layer is exposed to image-wise infrared radiation;

[0045] (c) one or more infrared radiation absorbers comprising an anionic chromophore having a net negative charge or an acidic group; and optionally

[0046] (d) one or more polymeric binders, all of which are different from all of components (a), (b) and (c).

[0047] In some embodiments of the manufacturing method of the present invention, the method further comprises between steps B) and C):

[0048] C') applying a second anodizing treatment to the aluminum-containing plate to form an aluminum oxide intermediate layer under the aluminum oxide outer layer, the aluminum oxide intermediate layer having an average dry thickness (T of at least 60 nm and up to and including 300 nm) m ), and contains many average intermediate pore diameters (D m ) is at least 20 nm and up to and including 60 nm of the intermediate micropores, wherein D m Greater than D o , D o Greater than D i , and the average dry thickness of the outer layer of aluminum oxide (T o ) is less than 150nm, and

[0049] The additional anodizing treatment of step D) is a third anodizing treatment for forming an inner layer of aluminum oxide below the intermediate layer of aluminum oxide.

[0050] The practice of the present invention has significantly reduced the problem of reducing imaging sensitivity when anionic infrared radiation absorbers are present in imaging chemistry. Specifically, it has been found that when phosphoric acid, phosphoric acid condensates or phosphates constitute the dominant component of the hydrophilic layer between the aluminum-containing substrate and the negative-type infrared radiation-sensitive imageable layer that can be developed on the machine, imaging sensitivity is maintained when anionic infrared radiation absorbers are used in imaging chemistry. These advantages are particularly evident when the aluminum-containing substrate has two or more aluminum oxide layers produced by anodizing (the last anodizing treatment is carried out using sulfuric acid). Anodized aluminum produced using sulfuric acid contains aluminum sulfate. Although aluminum sulfate is easily soluble in water in its pure form, the aluminum sulfate trapped in the anodized aluminum structure cannot be easily removed by a water rinsing step within the practical time frame of a typical printing plate precursor manufacturing machine. During the natural storage period of the lithographic printing plate precursor obtained from such an aluminum-containing substrate (especially in a humid environment), the aluminum sulfate retained in the aluminum-containing substrate can be slowly released.

[0051] It has been found that the release of aluminum sulfate into the on-press developable negative-working infrared radiation-sensitive imageable layer can be achieved at a rate of at least 50 mg / m 2 Up to and including 300 mg / m 2 The presence of (1) one or more phosphorus-containing compounds effectively blocks the presence of C1 dry coverage. Therefore, the formation of salts between the anionic chromophores of (c) one or more infrared radiation absorbers and the aluminum ions of aluminum sulfate released from the aluminum-containing substrate can be effectively prevented. If such salt formation is not prevented, the effectiveness of (c) one or more infrared radiation absorbers is significantly reduced. DETAILED DESCRIPTION OF THE INVENTION

[0053] definition

[0054] The term "aluminum-containing plate" is used herein to refer to an aluminum-containing material or other metal-containing material (sheet, mesh, strip, sheet, foil or other form) that can be subsequently processed to prepare a "substrate" as described in more detail below. Sometimes, this term is referred to in the art as a "support."

[0055] Average outer pore diameter (D o ) (in nanometers (nm)) can be determined from a top-down SEM image taken at a magnification of at least 50,000X from the substrate surface before applying the hydrophilic layer and the infrared radiation-sensitive imageable layer. It is also possible to determine the outer pore diameter (D) of the lithographic printing plate precursor by o ): The organic layer is stripped off with a suitable solvent and the outer portion of the aluminum oxide outer layer, about 20 nm to 80 nm thick, is optionally removed using a suitable technique such as argon ion beam sputtering, and then a top view of the SEM image is taken. The average value can be determined by examining more than 200 outer micropores.

[0056] Average inner pore diameter (D i ) can be determined from a cross-sectional SEM image at a magnification of at least 50,000X. The cross section can be generated by bending the lithographic printing plate precursor or its substrate after the imageable layer and the hydrophilic layer have been removed. During bending, cracks form in the aluminum oxide layer and new surfaces are formed, usually at the weakest locations, which are usually located at the thinnest walls between adjacent internal micropores. Thus, the new crack surface provides a cross-sectional view of many micropores. For the present invention, it is not necessary to determine the exact average internal micropore diameter (D i ), as long as at least 90% of the exposed micropore cross-sections have a width of less than 11 nm.

[0057] The average dry thickness of the outer layer of aluminum oxide in nanometers (nm) (T o ), the average dry thickness of the aluminum oxide middle layer and the average dry thickness of the aluminum oxide inner layer (T i ) can each be determined from a cross-sectional SEM image of at least 50,000X magnification. The cross section of the aluminum oxide layer can be revealed through a crack formed by bending the lithographic printing plate precursor or its aluminum-containing substrate. The cross section of each aluminum oxide layer can also be revealed by cutting a slit through the aluminum oxide layer by a technique well known in the art - focused ion beam (FIB).

[0058] In some embodiments, the micropore density (C o )(According to micropores / μm 2 The number of micropores can be determined from a top-view SEM picture at a magnification of at least 50,000X by counting the number of micropores in a square predetermined area having an area of, for example, 500 nm x 500 nm.

[0059] Additionally, in some embodiments, the porosity (P o ) can be constrained by each of the following equations:

[0060] 0.3≤P o ≤0.8 or

[0061] 0.3≤P o ≤0.6,

[0062] Where P o Defined as 3.14(C o )(D o 2 ) / 4,000,000.

[0063] The term "infrared radiation absorber" as used herein refers to a compound or material that absorbs electromagnetic radiation in a defined region, and generally refers to a compound or material, or a mixture thereof, having an absorption maximum in the region of at least 750 nm and at most 1400 nm.

[0064] For clarification of the definition of any term related to polymers, reference should be made to "Glossary of Basic Terms in Polymer Science", Pure Appl. Chem. 68, 2287-2311 (1996), published by the International Union of Pure and Applied Chemistry ("IUPAC"). However, any definition explicitly set forth herein should be considered decisive.

[0065] Unless otherwise indicated, the term "weight %" refers to the amount of a component or material based on the total solids of a composition, formulation or dry layer. Unless otherwise indicated, the percentage of total solids for a dry layer or a formulation or composition used to form the dry layer may be the same.

[0066] use

[0067] The lithographic printing plate precursors of the present invention ("inventive precursors") are useful for forming lithographic printing plates for lithographic printing, for example, using lithographic inks, fountain solutions, or both lithographic inks and fountain solutions. These precursors are prepared to have structures and components as described below. In addition, the inventive lithographic printing plate precursors are designed to be negative-working and on-press developable using appropriate materials and manufacturing procedures as described below to provide negative-working infrared radiation-sensitive formulations and imageable layers that can be developed on-press.

[0068] However, it is still possible to develop such inventive precursors off-line using a suitable developer if the user so desires.

[0069] Invention substrate

[0070] In general, the lithographic printing plate aluminum-containing substrate can be obtained from aluminum or other metallic materials, such as aluminum alloys containing up to 10% by weight of one or more elements, including but not limited to manganese, silicon, iron, titanium, copper, magnesium, chromium, zinc, bismuth, nickel and zirconium. The aluminum-containing support or aluminum-alloy-containing support (or "plate" or "raw material") can have any form (including sheets, continuous webs and curled strips) from which it can be further processed, as long as it has at least one (substantially flat) surface, which can be treated as described below to form a hydrophilic surface in the inventive substrate. It is also possible to use a polymer film or paper on which a pure aluminum layer or an aluminum alloy layer is deposited or laminated.

[0071] The resulting aluminum-containing substrate should be thick enough to mechanically withstand the conditions in a modern printing press, but thin enough to be mounted (or wound) on the printing cylinder of such a machine. Therefore, the aluminum-containing substrate should also have the appropriate tensile strength, elasticity, crystallinity and electrical conductivity required for lithographic printing. These properties can be achieved by standard methods such as heat treatment or cold and hot rolling (typically used to make continuous lithographic support strips, webs or rolls). The dry thickness of the resulting inventive substrate is generally at least 100 μm and up to and including 600 μm.

[0072] The described aluminum-containing plates can be processed using typical lithographic printing plate precursor manufacturing methods, including pre-etching, water rinsing, roughening, water rinsing, post-etching and final water rinsing procedures, in combination with two or more anodizing treatments described in more detail below.

[0073] The raw material aluminum-containing plate (or support) is usually subjected to a pre-etching step to remove oil, grease, and metal and other contaminants at or near the support surface. As known in the art, sodium hydroxide or other alkaline aqueous solutions or even some organic solvents can be used to carry out the pre-etching step at known concentrations, time and temperature. A separate or additional degreasing step can be carried out using a surfactant aqueous solution as required. The technician will be able to perform routine experiments to find the best pre-etching conditions (e.g., best solution concentration, residence time and temperature).

[0074] Typically, after the pre-etching step, the etched support is "roughened" in a suitable manner, such as by using known electrochemical or mechanical roughening (or grinding) methods. In the electrochemical grinding process, the etched support can be treated with an alternating current in a 5-20 g / L hydrochloric acid solution. It is also possible to use a nitric acid solution (e.g., up to 2.5 wt %) or a sulfuric acid solution or a mixture solution for this purpose. Such electrochemical grinding solutions may also contain additives, such as corrosion inhibitors and stabilizers, including but not limited to metal nitrates, metal chlorides, monoamines, diamines, aldehydes, phosphoric acid, chromic acid, boric acid, lactic acid, acetic acid and oxalic acid. For example, electrochemical grinding can be performed using the method described in U.S. Patent Application Publication 2008 / 0003411 (Hunter et al.). The technician will be able to determine the optimal conditions for electrochemical or mechanical grinding by routine experiments, as such methods are well known in the art. Mechanical grinding methods can be performed, for example, using a suitable brush alone or in combination with a slurry of an abrasive such as silica particles or alumina particles. Alternatively, a combination of mechanical and electrochemical graining methods may be used.

[0075] During roughening or graining, stains may form on the surface of the aluminum-containing support, and a post-etching step using a strongly acidic or alkaline solution may be used to remove, for example, 0.01-5.0 g / m 2The stain can be removed by treating the surface of the support. For example, sodium hydroxide solution, trisodium phosphate solution or sulfuric acid solution can be used for post-etching. The amount of post-etching can be controlled by setting the residence time, concentration and temperature of the etching solution. The appropriate amount of post-etching also depends on the amount of roughening and the amount of stain formed in this step. The post-etching treatment should be sufficient to remove the stain, but it should not destroy the surface structure formed in the roughening step too much. Therefore, there are many combinations of parameters that those skilled in the art can consider during routine experiments to find the best post-etching conditions.

[0076] The aforementioned steps produce an electrochemically grained (roughened) or mechanically grained (roughened) and etched surface in the aluminum-containing plate (or support) which can be provided in step A) of the production method according to the invention.

[0077] The subsequent steps carried out according to the present invention include at least a first anodizing treatment and a second anodizing treatment (both of which are essential to the present invention) to form an outer aluminum oxide layer and an inner aluminum oxide layer, respectively. The method of the present invention does not require additional anodizing treatments (i.e., a third anodizing treatment or more anodizing treatments), but one or more additional anodizing treatments are possible and are therefore optional.

[0078] Typically, a sulfuric acid or phosphoric acid (electrolyte) solution can be used for the first anodizing treatment and the second anodizing treatment at a temperature of at least 20°C and up to and including 70°C for a suitable time of at least 1 second and up to and including 250 seconds sufficient to provide up to and including 4 g / m 2 The conditions of both the first anodizing treatment and the second anodizing treatment are described as follows.

[0079] Thus, in step B), a suitable aluminum-containing plate having an electrochemically or mechanically grained and etched surface as described above is subjected to a first anodizing treatment to form an outer layer of aluminum oxide on the electrochemically or mechanically grained and etched surface. For example, an electrolyte composition containing at least 50 g / L and up to and including 350 g / L phosphoric acid or at least 150 g / L and up to and including 300 g / L sulfuric acid, and a suitable amount of aluminum ions (e.g., 5 g / L) can be used for the first anodizing treatment. These solution amounts can be optimized with respect to the type of acid, acid concentration, aluminum ion concentration, residence time, and temperature in order to achieve the desired aluminum oxide outer layer properties as described herein. Representative details of such a first anodizing treatment are exemplified in the working examples described below or in known techniques, such as U.S. Patent Application Publication 2018 / 0250925 (Merka et al.), U.S. Patent Nos. 9,259,954 (Tagawa et al.), 8,978,555 (Kurokawa et al.), 8,789,464 (Tagawa et al.), and 8,783,179 (Kurokawa et al.). It is particularly useful to use phosphoric acid for the first anodizing treatment.

[0080] The resulting alumina outer layer comprises a plurality of pores with an average outer diameter (D o ) is at least 12 nm or at least 15 nm, and up to and including 30 nm or even up to and including 50 nm of outer micropores. In addition, the average dry thickness (T o ) can be at least 20 nm or at least 50 nm or at least 130 nm or even at least 150, and up to and including 300 nm or up to and including 400 or up to and including 650 nm. In some embodiments, the micropore density (C) of the anodized outer layer is o ) can usually be at least 500 micropores / μm 2 and up to and including 3,000 micropores / μm 2 .

[0081] Furthermore, in some embodiments, the average outer pore diameter (D) in nanometers of the outer alumina layer can be further constrained or related according to each of the following equations: o ) and micropores / μm 2 The micropore density (C o ):

[0082] 0.3≤P o ≤0.8 or

[0083] 0.3≤P o ≤0.6,

[0084] The porosity P o Defined above.

[0085] Once the first anodizing treatment has been carried out for the desired time, the formed outer layer of aluminum oxide can be rinsed with a suitable solution (such as water) at a suitable temperature and time in step C) to remove residual acid and aluminum and stop the first anodizing treatment.

[0086] In some embodiments, the average outer pore diameter (D o ) is less than the value specified above (usually the case when the first anodizing treatment is carried out in sulfuric acid), a pore expansion treatment can be added after the first anodizing treatment and the optional rinsing treatment. The pore expansion treatment can be carried out in an acidic solution or an alkaline solution. Details on pore expansion treatments can be found in the known art, such as U.S. Patents 9,259,954, 8,978,555, 8,789,464 and 8,783,179 (all identified above). Such pore expansion treatments can be followed by another rinsing step using a suitable solution such as water to remove the acidic or alkaline components used in the pore expansion treatment.

[0087] Then step D) additional anodizing is performed using a suitable electrolyte composition to form an inner layer of aluminum oxide under the outer layer of aluminum oxide, and the electrolyte composition may contain at least 100 g / L and up to and including 350 g / L sulfuric acid, and a suitable amount (e.g., 5 g / L) of aluminum ions. These solution amounts can be optimized with respect to acid concentration, aluminum ion concentration, residence time, and temperature so as to achieve the desired inner layer properties of aluminum oxide as described herein. The details of such a second anodizing treatment are illustrated in the working examples described below. The additional anodizing treatment is typically the "second" and final anodizing treatment, but in some embodiments, the additional anodizing treatment is the third and final anodizing treatment used to form an inner layer of aluminum oxide below the aluminum oxide intermediate layer (described below).

[0088] The resulting inner layer of aluminum oxide disposed on the grained and etched surface of the substrate comprises a plurality of average inner micropores having a diameter (D i ) is less than or equal to 11 nm. In such embodiments, D o With D i The ratio of may be greater than 1.1:1, or even greater than 1.5:1. In addition, the average dry thickness (T i ) can be at least 300 nm or at least 500 nm, and up to and including 1500 nm or up to and including 3,000 nm.

[0089] In some embodiments, the outer aluminum oxide layer is disposed directly on the inner aluminum oxide layer, and the average dry thickness (T o ) is at least 50 nm, and the average inner pore diameter (Di ) is equal to or less than 11 nm, and the average dry thickness of the inner layer of aluminum oxide (T i ) is at least 500 nm, and the inner pore diameter (D i ) is smaller than the average outer pore diameter (D o ).

[0090] Once the second anodizing treatment has been carried out for the required time, the formed outer and inner aluminum oxide layers can be rinsed with a suitable solution (such as water) at a suitable temperature and time to remove residual acid and aluminum salts and stop the second anodizing treatment.

[0091] In some embodiments of the present invention, the aluminum-containing support is subjected to a second (but not final) anodizing treatment (step C')) between step C) and step D) using a suitable acid or mixture thereof for a suitable time and at a suitable temperature to provide an aluminum oxide intermediate layer under the aluminum oxide outer layer. The second anodizing treatment is performed after the first anodizing treatment and before the third anodizing treatment for forming the aluminum oxide inner layer. Thus, an aluminum oxide intermediate layer is typically formed between the aluminum oxide outer layer and the later formed aluminum oxide inner layer. In such embodiments, the aluminum oxide intermediate layer formed may have an average dry thickness (T of at least 60 nm and up to and including 300 nm). m ), and may contain a number of average intermediate pore diameters (D m ) are at least 20 nm and up to and including 60 nm in size.

[0092] In such embodiments, D m Greater than D o , D o Greater than D i , and T o can be less than 150 nm, and the average dry thickness of the outer layer of aluminum oxide (T o ) is less than 150nm.

[0093] After forming this aluminium oxide intermediate layer, and before forming the aluminium oxide inner layer as indicated above, the aluminium oxide outer layer and the aluminium oxide intermediate layer may be rinsed in step C″) in the manner as described above for the aluminium oxide outer layer alone.

[0094] According to the present invention, it is necessary to provide a hydrophilic layer in step F) so as to be disposed on the outer layer of aluminum oxide. The hydrophilic layer can be provided by a hydrophilic layer formulation comprising: (1) one or more phosphorus-containing compounds having a C1 dry coverage, the one or more phosphorus compounds being represented by formula (I) described below; and optionally (2) one or more hydrophilic polymers having a C2 dry coverage.

[0095] The hydrophilic layer has a total of at least 50 mg / m 2 Up to and including 500 mg / m 2 Typically, the hydrophilic layer is disposed directly on the outer alumina layer, so that no intermediate layer exists. Since the outer alumina layer contains micropores, some (portions) of the hydrophilic layer may be located in micropores within such outer micropores and below the outer alumina layer.

[0096] When both (1) and (2) are present, the ratio of C1 dry coverage to C2 dry coverage is at least 11:9, and the ratio may be up to and including 10:1 or up to and including 30:1, and is typically applied or disposed on the outer layer of aluminum oxide to provide a dry coverage of the hydrophilic layer. The C1 dry coverage may be at least 50 mg / m 2 or at least 75 mg / m 2 , up to and including 200 mg / m 2 Up to and including 300 mg / m 2 C2 dry coverage may be zero or up to and including 200 mg / m 2 , or up to and including 100 mg / m 2 Up to and including 50 mg / m 2 .

[0097] The (1) one or more phosphorus-containing compounds necessary for the hydrophilic layer are represented by the following formula (I):

[0098]

[0099] wherein n is 0 or an integer from 1 to 10 (and n is especially 0). In addition, -OM represents -OH or -O - M + , where M + is a monovalent cation, such as H + , sodium cation, potassium cation, ammonium cation, alkylammonium cation, dialkylammonium cation, trialkylammonium cation or tetraalkylammonium cation. Examples of the alkyl group in the alkylammonium cation, dialkylammonium cation, trialkylammonium cation and tetraalkylammonium cation include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and sec-butyl. + The cations may be the same or different in the same molecule. The alkyl groups may be the same or different in the same cation. Such alkyl groups may be substituted or unsubstituted as will be readily determined by a skilled chemist. + Among the cations, ammonium (NH4 + ) is particularly suitable.

[0100] In addition, the -OM group is selected for the one or more phosphorus-containing compounds of formula (I) (1) so that it (alone or in a mixture of such compounds) exhibits a pH of at least 1 and up to and including 10, or at least 1 and up to and including 8 when dissolved in an aqueous solution containing 5 wt % of the one or more phosphorus-containing compounds of formula (I) (1). When two or more phosphorus-containing compounds are used, the mixture of the two or more phosphorus-containing compounds is selected to also meet this pH requirement.

[0101] Compounds represented by formula (I) can be obtained from various commercial sources or synthesized by a skilled chemist using known starting materials and synthetic procedures.

[0102] The hydrophilic layer used in the practice of the present invention optionally but preferably comprises (2) one or more hydrophilic polymers at C2 dry coverage defined above. By "hydrophilic" with respect to these polymers it is meant that the solubility of these polymers in water at 25°C is at least 1%.

[0103] More specifically, (2) at least one of the one or more hydrophilic polymers comprises a carboxylic acid side group, a phosphonic acid side group or a phosphoric acid side group, a salt of these groups (carboxylates, phosphonates and phosphates) or a combination of two or more of these acidic side groups (or their salts). These acid and salt groups contribute to the water solubility of the hydrophilic polymer and therefore contribute to the adhesion of these hydrophilic polymers to the anodized aluminum surface. Therefore, these acid and salt groups can be considered as surface-bound hydrophilic groups. In addition to the surface-bound hydrophilic groups, the hydrophilic polymer may also contain non-surface-bound hydrophilic groups that primarily contribute to the water solubility of the hydrophilic polymer. Useful non-surface-bound hydrophilic groups include, but are not limited to, amide groups, hydroxyl groups, sulfonate groups and polyethylene oxide groups.

[0104] (2) One or more hydrophilic polymers can be synthesized via polycondensation or addition polymerization using monomers having surface-bound hydrophilic groups and non-surface-bound hydrophilic groups. Free radical initiators, cationic initiators and anionic initiators can be used to initiate addition polymerization of suitable ethylenically unsaturated polymerizable monomers. The surface-bound hydrophilic groups and non-surface-bound hydrophilic groups on these hydrophilic polymers can be introduced via polymerization of monomers having these groups or formed by reaction of suitable precursor polymers having precursor side groups that can be converted into surface-bound hydrophilic groups and non-surface-bound hydrophilic groups. Among the various synthesis techniques for preparing (2) one or more hydrophilic polymers of the present invention, free radical addition polymerization of the following monomer composition is particularly useful: the monomer composition comprises ethylenically unsaturated polymerizable monomers having surface-bound (hydrophilic groups) and optionally ethylenically unsaturated polymerizable monomers having non-surface-bound hydrophilic groups.

[0105] Examples of useful ethylenically unsaturated polymerizable monomers having surface-bound hydrophilic groups include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid, maleic acid, vinylphosphonic acid, acryloyloxyethyl phosphate, methacryloyloxyethyl phosphate, polyethylene glycol acrylate phosphate, and polyethylene glycol methacrylate phosphate.

[0106] Examples of useful ethylenically unsaturated polymerizable monomers with non-surface-bound hydrophilic groups include, but are not limited to, methacrylamide, acrylamide, N,N-dimethylacrylamide, N-hydroxyethyl methacrylamide, N-(methoxymethyl) acrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, N-vinyl pyrrolidone, sodium p-styrene sulfonate, sodium acrylamidopropyl sulfonic acid salt, and polyethylene glycol methyl ether methacrylate. A mixture of two or more of these monomers can be used to provide a variety of repeating units. Among the monomers with non-surface-bound hydrophilic groups, those with at least one amide group such as acrylamide or methacrylamide are particularly useful. In some embodiments, the repeating units derived from the monomers with amide groups can account for up to 95mol% of the total amount of repeating units in the hydrophilic polymer, and the repeating units derived from the monomers with hydrophilic surface-bound groups (e.g., one or more of carboxylic acid groups, carboxylates, or carboxylate salts) can account for up to and include 50mol%, typically up to and include 40mol% or up to and include 30mol%.

[0107] Thus, in some embodiments where (2) one or more hydrophilic polymers are present in the hydrophilic layer, (2) the one or more hydrophilic polymers include a hydrophilic polymer comprising the following repeating units: repeating units comprising carboxylic acid, phosphonic acid, phosphoric acid groups, or salts or esters of any of these acids; and optionally repeating units comprising amide groups.

[0108] If (2) a mixture of one or more hydrophilic polymers is present, they may have different repeat unit compositions and / or different repeat unit amounts.

[0109] In addition to (1) one or more phosphorus-containing compounds (with or without (2) one or more hydrophilic polymers), the hydrophilic layer may also include one or more surfactants, leveling agents, chelating agents, and biocides.

[0110] The method for forming the hydrophilic layer can be carried out in any suitable manner as described, for example, in

[0058] -

[0061] of U.S. Patent Application Publication 2014 / 0047993 (noted above). A particularly useful technique for forming the hydrophilic layer is to apply the desired amount of the hydrophilic layer formulation in a suitable solvent such as water directly to the outer layer of aluminum oxide, and then allow the resulting wet coating to dry.

[0111] After all these necessary treatments, the resulting inventive aluminum-containing substrate in any suitable form (eg, a flat sheet or a continuous web or roll) is ready for use in the preparation of lithographic printing plate precursors according to the invention.

[0112] Infrared radiation sensitive imageable layers and precursors

[0113] Generally speaking, a single press-developable negative-working infrared radiation-sensitive imageable layer can be formed or disposed in a suitable manner over the hydrophilic layer of the aluminum-containing substrate of the invention using a suitable press-developable negative-working infrared radiation-sensitive imageable layer formulation as described in more detail below.

[0114] Negative-working lithographic printing plate precursors:

[0115] The precursor of the invention can be formed by suitably applying a negative-working infrared radiation-sensitive composition developable on press as described below to a suitable aluminum-containing substrate of the invention (as described above) to form a negative-working infrared radiation-sensitive imageable layer developable on press on the substrate. Generally speaking, the negative-working infrared radiation-sensitive composition developable on press (and the resulting negative-working infrared radiation-sensitive imageable layer developable on press) comprises as essential components (a) one or more free radical polymerizable components; (b) an initiator composition that provides free radicals upon exposure to imaging radiation (e.g., infrared radiation as defined herein); and (c) an infrared radiation absorber that comprises an anionic chromophore having a net negative charge or an acidic group; and optionally a polymeric binder different from all of (a), (b), and (c), all of which are described in more detail below. The press-developable negative-working infrared radiation-sensitive imageable layer is typically the outermost layer in the precursor, but in some embodiments there may be an outermost overcoat (also called a topcoat or oxygen barrier layer, and described below) disposed thereover as the outermost layer.

[0116] The negative-working infrared radiation-sensitive composition that can be developed on press (and the negative-working infrared radiation-sensitive imageable layer that can be developed on press prepared therefrom) comprises (a) one or more free radical polymerizable components, each of which contains one or more free radical polymerizable groups (and in some embodiments two or more such groups) that can be polymerized using free radical initiation. In some embodiments, the negative-working infrared radiation-sensitive imageable layer that can be developed on press comprises two or more free radical polymerizable components, which have the same or different numbers of free radical polymerizable groups in each molecule.

[0117] Useful free radical polymerizable components can contain one or more free radical polymerizable monomers or oligomers, which have one or more ethylenically unsaturated groups (e.g., two or more such groups) that can be addition polymerized. Similarly, crosslinkable polymers with such free radical polymerizable groups can also be used. Oligomers or prepolymers can be used, such as urethane acrylates and urethane methacrylates, epoxide acrylates and epoxide methacrylates, polyester acrylates and polyester methacrylates, polyether acrylates and polyether methacrylates, and unsaturated polyester resins. In some embodiments, the free radical polymerizable component comprises a carboxyl group.

[0118] One or more free radically polymerizable components may have a sufficiently large molecular weight to enhance the mechanical properties of the on-press developable negative-working infrared radiation-sensitive imageable layer and thereby render the corresponding lithographic printing plate precursor suitable for shipping in typical packaging and for handling during normal prepress operations.

[0119] Numerous other free radical polymerizable components are known in the art and are described in a considerable literature, including EP 1,182,033A1 (Fujimaki et al.) (beginning at paragraph

[0170] ), as well as U.S. Patents 6,309,792 (Hauck et al.), 6,569,603 (Furukawa) and 6,893,797 (Munnelly et al.) and U.S. Patent Application Publication 2009 / 0142695 (Baumann et al.).

[0120] The amount of (a) one or more free radically polymerizable components present in the negative-working infrared radiation-sensitive imageable layer that can be developed on the press is generally at least 10 weight percent or at least 20 weight percent, and up to and including 50 weight percent or up to and including 70 weight percent, all based on the total dry weight of the negative-working infrared radiation-sensitive imageable layer that can be developed on the press.

[0121] The press-developable negative-working infrared radiation-sensitive imageable layer used in the present invention also contains (b) an initiator composition which, in the presence of a suitable infrared radiation absorber, provides free radicals to initiate polymerization of one or more free radical polymerizable components when the press-developable negative-working infrared radiation-sensitive imageable layer is exposed to suitable imaging infrared radiation.

[0122] Initiator compositions useful for infrared radiation sensitive compositions and imageable layers include, but are not limited to, onium salts, such as ammonium, iodonium, sulfonium and phosphonium compounds described in detail in

[0131] of U.S. Patent Application Publication 2014 / 0047993 (noted above). Examples of onium salts include triarylsulfonium (salts), diaryliodonium (salts), diaryldiazonium (salts), wherein the aryl group includes phenyl and naphthyl, and may be substituted.

[0123] Onium salts can be obtained by combining an onium salt having a sulfonium or iodonium cation in the molecule with an onium salt in the molecule. The onium salt may be a polyvalent onium salt having at least two onium ion atoms bonded by a covalent bond in the molecule. Among polyvalent onium salts, those having at least two onium ion atoms in the molecule are useful, and those having a sulfonium or iodonium cation in the molecule are particularly useful. Representative polyvalent onium salts are represented by the following formulas (6) and (7):

[0124]

[0125] Furthermore, onium salts described in paragraphs

[0033] to

[0038] of the specification of Japanese Patent Publication No. 2002-082429 [or U.S. Patent Application Publication No. 2002-0051934 (Ippei et al.)] or iodonium borate complexes described in U.S. Patent No. 7,524,614 (noted above) can also be used.

[0126] Anions useful for iodonium salts include, but are not limited to, ClO4 - PF6 - 、BF4 - 、SbF6 - 、CH3SO3 - CF3SO3 - 、C6H5SO3 - 、CH3C6H4SO3 - 、HOC6H4SO3 - 、ClC6H4SO3 - and a borate anion represented by the following structure (VII):

[0127] B-(R 1 )(R 2 )(R 3 )(R 4 )

[0128] (VII_

[0129] Where R 1 , R 2 , R 3 and R 4 R independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group (including a halogen-substituted aryl group), a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted heterocyclic group, or R 1 , R 2 , R 3 and R 4Two or more of may be linked together to form a substituted or unsubstituted heterocyclic ring having a boron atom, such ring having up to 7 carbon atoms, nitrogen atoms, oxygen atoms or sulfur atoms. 1 , R 2 , R 3 and R 4 are identical or different substituted or unsubstituted aryl groups, such as substituted or unsubstituted phenyl groups, or more likely, all of these groups are unsubstituted phenyl groups. In many embodiments, at least one of X1, X2, and X3 is a tetraarylborate anion containing identical or different aryl groups, or in particularly useful embodiments, one or more of (X1, X2, and X3) is a tetraphenylborate anion or X1, X2, and X3 are each a tetraphenylborate anion.

[0130] The initiator composition is typically present in the on-press developable negative-working infrared radiation-sensitive imageable layer in an amount sufficient to provide one or more polymerization initiators in an amount of at least 0.5 weight percent, or at least 2 weight percent, or even at least 4 weight percent, and up to and including 12 weight percent, or up to and including 15 weight percent, or up to and including 20 weight percent, all based on the total dry weight of the on-press developable negative-working infrared radiation-sensitive imageable layer.

[0131] In addition, the infrared radiation sensitive imageable layer that can be developed on the press further comprises (c) one or more infrared radiation absorbers, each of which comprises an anionic chromophore having a net negative charge or an acidic group to provide the desired infrared radiation sensitivity when imaged using an appropriate imaging device (e.g., a laser that emits infrared radiation) responsive to digital information. In other words, none of these one or more infrared radiation absorbers contain a cationic chromophore having a net positive charge and no acidic group, and none of these one or more infrared radiation absorbers have a net zero charge and no acidic group.

[0132] (c) The one or more infrared radiation absorbers may each further comprise one or more suitable counterions for the anionic chromophore, as will be readily apparent to one skilled in the art.

[0133] Suitable one or more infrared radiation absorbers are known in the art and may be infrared radiation absorbing dyes containing anionic chromophores having the requisite net negative charge, including but not limited to those described in U.S. Pat. Nos. 6,511,782 (Vermeersch et al.), 5,208,135 (Patel et al.), 7,368,215 (Munnelly et al.), 8,409,780 (Callant et al.), and 8,778,590 (Callant).

[0134] One particularly useful class (c) of one or more infrared radiation absorbers according to the present invention comprises an anionic chromophore represented by the following formula (II):

[0135]

[0136] in:

[0137] Each X independently represents >S, >O, >NR or >C(R)2;

[0138] Each R 1 is independently optionally substituted alkyl;

[0139] R 2 represents hydrogen, halogen, -SR, -SO2R, -OR or -NR2 group;

[0140] Each R 3 independently represents a hydrogen atom, an optionally substituted alkyl group, -COO-, -COOR, -OR, -SR, -NR2, a halogen atom, a sulfonate group, or an optionally substituted benzo-fused ring;

[0141] --- represents an optional five-membered carbocyclic ring or a six-membered carbocyclic ring;

[0142] each R independently represents hydrogen, optionally substituted alkyl or optionally substituted aryl;

[0143] each n is independently 0, 1, 2 or 3; and

[0144] R 1 , R 2 and R 3 At least one comprises one or more of a sulfonate group, a sulfonic acid group, a carboxylate group, and a carboxylic acid group sufficient to provide a net negative charge or an acidic group to Formula (II).

[0145] In some embodiments it is desirable that R 1 , R 2 and R 3 At least one of them comprises a carboxylate group to provide a net negative charge or an acidic group to formula (II).

[0146] The net negative charge on the anionic chromophore represented by formula (II) can be transferred via the cation Z + Balance to form a neutral infrared radiation absorber. Suitable cations Z + Including M as described in formula (I) + and an onium salt, such as a cation of a diaryliodonium salt as described above for the (b) initiator composition.

[0147] Specific examples of useful anionic infrared radiation absorbers (AIR) having a chromophore represented by formula (II) are shown below.

[0148]

[0149]

[0150]

[0151]

[0152]

[0153]

[0154] The total dry coverage of (c) one or more radiation absorbers in the negative-working infrared radiation-sensitive imageable layer which can be developed on press is at least 5 mg / m 2 or at least 10 mg / m 2 , up to and including 100 mg / m 2 Up to and including 200 mg / m 2 .

[0155] Optionally but desirably in many embodiments, the on-press developable negative-working infrared radiation-sensitive imageable layer further comprises one or more (d) polymer binders (or materials acting as polymer binders) for all materials in the indicated layer. Such polymer binders are different from all of the (a), (b), and (c) materials described above. These polymer binders are generally non-crosslinkable and non-polymerizable, and at least one of these polymer binders may be in particulate form.

[0156] Such (d) polymer binders can be selected from numerous polymer binder materials known in the art, including polymers comprising repeating units having side chains comprising polyoxyalkylene segments, such as those described in, for example, U.S. Pat. No. 6,899,994 (Huang et al.). Other useful (d) polymer binders include two or more types of repeating units having different side chains comprising polyoxyalkylene segments, such as those described in, for example, WO Publication 2015-156065 (Kamiya et al.). Some of such (d) polymer binders may further include repeating units having cyano side groups, such as those described in, for example, U.S. Pat. No. 7,261,998 (Hayashi et al.).

[0157] Some useful (d) polymer binders can be in the form of particles, that is, in the form of discrete non-agglomerated particles. The average particle size of such discrete particles can be at least 10nm and up to and including 1500nm, or generally at least 80nm and up to and including 600nm, and is generally evenly distributed in the negative plate-making infrared radiation sensitive imageable layer that can be developed on the machine. For example, one or more useful (d) polymer binders can be present in the form of particles having an average particle size of at least 50nm and up to and including 400nm. The average particle size can be determined by various known methods, which include measuring the particles in the electron scanning microscope image and taking the average value of a certain number of measured values.

[0158] The (d) polymer binder may also have a backbone comprising a plurality (at least two) of urethane moieties and pendant groups comprising polyoxyalkylene segments.

[0159] Other useful (d) polymer binders may include polymerizable groups such as acrylate groups, methacrylate groups, vinyl aryl groups, and allyl groups; and alkali soluble groups such as carboxylic acids. Some of these useful (d) polymer binders are described in U.S. Patent Application Publication No. 2015 / 0099229 (Simpson et al.) and U.S. Patent No. 6,916,595 (Fujimaki et al.).

[0160] Useful (d) polymeric binders typically have a weight average molecular weight (Mw) of at least 2,000 and up to and including 500,000, or at least 20,000 and up to and including 300,000, as determined by gel permeation chromatography (polystyrene standards).

[0161] The total amount of (d) polymer binder present in the press-developable negative-working infrared radiation-sensitive imageable layer can be at least 10 weight percent or at least 20 weight percent and up to and including 50 weight percent or up to and including 70 weight percent, based on the total dry weight of the press-developable negative-working infrared radiation-sensitive imageable layer.

[0162] Other polymeric materials known in the art (different from the (d) polymeric binder) may be present in the on-press developable negative-working infrared radiation-sensitive imageable layer, and such polymeric materials are generally more hydrophilic or more hydrophobic than the (d) polymeric binder described above. Examples of such hydrophilic polymeric binders include, but are not limited to, cellulose derivatives, such as hydroxypropyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol with various degrees of saponification. The more hydrophobic polymeric binders are less developable than the (d) polymeric binders described above, and generally have an acid value of less than 20 mg KOH / g for all acidic groups with a pKa below 7 and their corresponding salts.

[0163] Additional optional additives for the on-press developable negative-working infrared radiation-sensitive imageable layer may include organic dyes or organic dye precursors and color developers as known in the art. Such optional additives may be used as print-out colorants and may be present in an amount of at least 1 wt % and up to and including 10 wt %, based on the total dry weight of the on-press developable negative-working infrared radiation-sensitive imageable layer.

[0164] Other useful print-out colorants are known in the art and may include azo dyes, triarylmethane dyes, cyanine dyes, and spironolactone or spironolactam colorants as described, for example, in U.S. Patent Application Publication 2009 / 0047599 (Horne et al.), and various print-out chemicals described in the following literature: U.S. Patent Application Publications 2021 / 0078350 (Viehmann et al.) and 2021 / 0302834 (Viehmann et al.), and U.S. Serial Nos. 17 / 685,570 (filed by Simpson et al. on March 3, 2022), 17 / 685,592 (filed by Simpson et al. on March 3, 2002), and 17 / 720,405 (filed by Hansmann et al. on April 14, 2022).

[0165] The on-press developable negative-working infrared radiation-sensitive imageable layer may include crosslinked polymer particles as described, for example, in U.S. Pat. Nos. 8,383,319 (Huang et al.), 8,105,751 (Endo et al.), and 9,366,962 (Kamiya et al.), having an average particle size of at least 2 μm or at least 4 μm, and up to and including 20 μm.

[0166] Overlay:

[0167] Although in many embodiments of the inventive lithographic printing plate precursors, the on-press developable negative-working radiation-sensitive imageable layer is the outermost layer with no layers disposed thereon, it is possible that the inventive precursors can be designed with a layer (also referred to in the art as an overcoat or topcoat) disposed above (or directly on) the on-press developable negative-working infrared radiation-sensitive imageable layer (with no intervening layers between the two layers). When present, such an overcoat is typically the outermost layer of the precursor and can be hydrophilic or hydrophobic.

[0168] The overcoat may contain one or more film-forming water-soluble polymer binders in an amount of at least 60 wt % and up to and including 100 wt %, based on the total dry weight of the hydrophilic overcoat. Such film-forming water-soluble (or hydrophilic) polymer binders may include modified or unmodified polyvinyl alcohols having a saponification degree of at least 30%, or at least 75%, or at least 90%, and up to and including 99.9%.

[0169] At least 0.1g / m 2 or at least 0.15g / m 2 And up to and including 2.5g / m 2 But less than 4g / m 2 In some embodiments, the dry coating coverage is as low as 0.1 g / m 2 And up to and including 1.5g / m 2 or at least 0.1g / m 2 And up to and including 0.9g / m 2 , so that the cover layer is relatively thin.

[0170] Preparation of lithographic printing plate precursors

[0171] The inventive lithographic printing plate precursors may be provided in the following manner. A negative-working infrared radiation-sensitive imageable layer formulation comprising the materials described above, which may be developed on-press, may be applied to an inventive aluminum-containing substrate as described above (which is typically in the form of a continuous substrate roll or web) using any suitable equipment and procedures such as spin coating, blade coating, gravure coating, die coating, slot coating, rod coating, wire rod coating, roller coating, or extrusion hopper coating. A negative-working infrared radiation-sensitive imageable layer formulation which may be developed on-press may also be applied to a suitable inventive aluminum-containing substrate by spraying. Typically, once the formulation is applied at a suitable wet coverage, it is dried in a suitable manner known in the art to provide the desired dry coverage as indicated below, thereby providing an infrared radiation-sensitive continuous article which may be in any suitable form (e.g., a web) from which a separate precursor may be prepared using known manufacturing methods.

[0172] The method of manufacture generally involves mixing the various components required for a particular on-press developable negative-working infrared radiation-sensitive imageable layer chemistry in a suitable organic solvent or mixture thereof and removing the solvent by evaporation under suitable drying conditions.

[0173] After appropriate drying, the dry coverage of the negative-working infrared radiation-sensitive imageable layer, which can be developed on the press, on the inventive substrate is typically at least 0.1 g / m 2 or at least 0.4g / m 2 , and up to and including 2g / m 2 or up to and including 4 g / m2 , but other dry coverage amounts may be used as desired.

[0174] Under actual manufacturing conditions, the result of these coating operations is a continuous web or roll of infrared radiation-sensitive lithographic printing plate precursor material having a press-developable negative-working infrared radiation-sensitive imageable layer and any optional layers (indicated above) disposed on the inventive aluminum-containing substrate described above.

[0175] Imaging (exposure) conditions

[0176] During use, the lithographic printing plate precursors of the invention may be exposed on-press to a suitable source of exposing infrared radiation, depending on the infrared radiation absorber present in the on-press developable negative-working infrared radiation-sensitive imageable layer. For example, the lithographic printing plate precursor may be imaged with an infrared laser emitting significant radiation in the range of at least 750 nm and up to and including 1400 nm, or in the range of at least 800 nm and up to and including 1250 nm. The result of such image-wise exposure is to provide exposed and unexposed areas in the exposed on-press developable negative-working infrared radiation-sensitive imageable layer.

[0177] Imaging can be performed using imaging or exposing infrared radiation from a laser (or an array of such lasers) that generates infrared radiation. Imaging can also be performed using imaging infrared radiation at multiple wavelengths simultaneously, if desired. The lasers used to expose the inventive precursors are typically diode lasers due to the reliability and low maintenance of diode laser systems, but other lasers such as gas lasers or solid-state lasers can also be used. The combination of power, intensity, and exposure time for infrared radiation imaging will be readily apparent to those skilled in the art.

[0178] Depending on the sensitivity of the negative-working infrared radiation-sensitive imageable layer that can be developed on-press, the infrared radiation imaging energy can be at least 30 mJ / cm 2 and up to and including 500 mJ / cm 2 and usually at least 50 mJ / cm 2 and up to and including 300 mJ / cm 2 .

[0179] Processing (development) and printing

[0180] Following image-wise infrared exposure, the exposed precursor having exposed and unexposed areas in a radiation-sensitive imageable layer that can be developed on press can be processed on press in a suitable manner to remove the unexposed areas and any overcoat layer (if present) and leave the hardened exposed areas intact.

[0181] For example, the inventive precursor is made developable on-press using a lithographic ink, a fountain solution, or a combination of a lithographic ink and a fountain solution. In such embodiments, the imaged negative-working infrared radiation-sensitive lithographic printing plate precursor developable on-press according to the present invention can be mounted on a printing press, and then the printing operation is started. In preparing the initial printing run, the unexposed areas in the negative-working infrared radiation-sensitive imageable layer developable on-press are removed by a suitable fountain solution, a lithographic ink, or a combination of the two.

[0182] In a typical printing press started with a sheet-fed printing press, the dampening rollers are first engaged and dampening solution is supplied to the mounted imaged precursor to swell the exposed negative-working infrared radiation-sensitive imageable layer that can be developed on-press at least in the unexposed areas. After several rotations, the inking rollers are engaged and they supply lithographic ink to cover the entire printing surface of the lithographic printing plate. Typically, within 5 to 20 rotations after the inking rollers are engaged, the printing sheet is supplied to remove the unexposed areas of the negative-working infrared radiation-sensitive imageable layer that can be developed on-press and the material on the blanket cylinder (if present) from the lithographic printing plate using the formed ink-fountain solution emulsion.

[0183] The present invention provides at least the following embodiments individually or in any suitable combination:

[0184] 1. A lithographic printing plate precursor comprising:

[0185] an aluminum-containing substrate having a hydrophilic surface, and

[0186] a negative-working, infrared radiation-sensitive imageable layer disposed on a hydrophilic surface of an aluminum-containing substrate,

[0187] The aluminum-containing substrates include:

[0188] an aluminum-containing plate having a ground and etched surface;

[0189] An inner layer of aluminum oxide is disposed on the grained and etched surface, the inner layer of aluminum oxide having an average dry thickness (T i ), and contains many average inner pore diameters (D i ) inner micropores less than or equal to 11 nm, wherein the inner layer of aluminum oxide comprises aluminum sulfate;

[0190] The outer aluminum oxide layer is disposed on the inner aluminum oxide layer, and the outer aluminum oxide layer comprises a plurality of pores having an average outer diameter (D o ) of at least 12 nm and up to and including 50 nm of outer micropores, and having an average dry thickness (T of at least 20 nm and up to and including 650 nm) o );as well as

[0191] A hydrophilic layer disposed on the outer layer of aluminum oxide, wherein the hydrophilic layer comprises: (1) one or more phosphorus-containing compounds having a C1 dry coverage and represented by the following formula (I):

[0192]

[0193] wherein n is 0 or an integer from 1 to 10, and -OM represents -OH or -OM + , and M + is a monovalent cation; and optionally (2) one or more hydrophilic polymers, which when present have a C2 dry coverage,

[0194] Where (1) the C1 dry coverage of one or more phosphorus-containing compounds is at least 50 mg / m 2 Up to and including 300 mg / m 2 , and when (2) one or more hydrophilic polymers are present, the ratio of C1 dry coverage to C2 dry coverage is at least 11:9; and

[0195] The on-press developable negative-working infrared radiation-sensitive imageable layer comprises the following components (a) to (c) and optionally component (d):

[0196] (a) one or more free radical polymerizable components;

[0197] (b) an initiator composition that provides free radicals when the on-press developable negative-working infrared radiation-sensitive imageable layer is exposed to image-wise infrared radiation;

[0198] (c) one or more infrared radiation absorbers comprising an anionic chromophore having a net negative charge or an acidic group; and optionally (d) one or more polymeric binders, all of which are different from all of components (a), (b) and (c).

[0199] 2. The lithographic printing plate precursor of embodiment 1, wherein the C1 dry coverage is at least 75 mg / m 2 Up to and including 200 mg / m 2 .

[0200] 3. The lithographic printing plate precursor of embodiment 1 or 2, wherein the ratio of C1 dry coverage to C2 dry coverage is at least 11:9 and up to and including 30:1, wherein (2) the one or more hydrophilic polymers are present in the hydrophilic layer.

[0201] 4. The lithographic printing plate precursor of any of embodiments 1 to 3, wherein (c) the one or more infrared radiation absorbers are present in an amount of at least 5 mg / m 2 Up to and including 200 mg / m 2The dry coverage is present in the on-press developable negative-working infrared radiation-sensitive imageable layer.

[0202] 5. A lithographic printing plate precursor of any of embodiments 1-4, wherein (2) one or more hydrophilic polymers are present in the hydrophilic layer, and (2) the one or more hydrophilic polymers include hydrophilic polymers comprising the following repeating units: repeating units comprising carboxylic acid, phosphonic acid, phosphoric acid groups, or salts or esters of any of these acids; and optionally repeating units comprising amide groups.

[0203] 6. The lithographic printing plate precursor of any of embodiments 1 to 5, wherein M + Independently selected from the group consisting of protons, sodium cations, potassium cations, ammonium cations, alkylammonium cations, dialkylammonium cations, trialkylammonium cations, and tetraalkylammonium cations, wherein each alkyl group is optionally substituted.

[0204] 7. A lithographic printing plate precursor of any of embodiments 1-6, wherein the -OM group is selected so that (1) one or more phosphorus-containing compounds represented by formula (I) exhibit a pH of at least 1 and up to and including 10 when dissolved in an aqueous solution containing 5 weight % of (1) one or more phosphorus-containing compounds represented by formula (I).

[0205] 8. The lithographic printing plate precursor of any of embodiments 1 to 7, wherein the anionic chromophore having a net negative charge or an acidic group is represented by the following formula (II):

[0206]

[0207] in:

[0208] Each X independently represents >S, >O, >NR or >C(R)2;

[0209] each R' is independently an optionally substituted alkyl group;

[0210] R 2 represents hydrogen, halogen, -SR, -SO2R, -OR or -NR2 group;

[0211] Each R 3 independently represents a hydrogen atom, an optionally substituted alkyl group, -COO - , -COOR, -OR, -SR, -NR2, a halogen atom, a sulfonate group, or an optionally substituted benzo-fused ring;

[0212] --- represents an optional five-membered carbocyclic ring or a six-membered carbocyclic ring;

[0213] each R independently represents hydrogen, optionally substituted alkyl or optionally substituted aryl;

[0214] each n is independently 0, 1, 2 or 3; and

[0215] R 1 , R 2 and R 3 At least one comprises a sulfonate group, a carboxylate group, or both a sulfonate group and a carboxylate group to provide a net negative charge or an acidic group to formula (II).

[0216] 9. The lithographic printing plate precursor of embodiment 8, wherein R 1 , R 2 and R 3 At least one of them comprises a carboxylate group to provide a net negative charge or an acidic group to formula (II).

[0217] 10. The lithographic printing plate precursor of any of embodiments 1 to 9, wherein the outer layer of aluminum oxide has an average dry thickness (T o ), and the outer aluminum oxide layer is directly disposed on the inner aluminum oxide layer; the average dry thickness of the inner aluminum oxide layer (T i ) is at least 500 nm, and the average inner pore diameter (D i ) is less than or equal to 11 nm and less than the average outer pore diameter (D o ).

[0218] 11. The lithographic printing plate precursor of any of embodiments 1-10, wherein the aluminum-containing substrate further comprises an aluminum oxide intermediate layer disposed between the aluminum oxide inner layer and the aluminum oxide outer layer, wherein the aluminum oxide intermediate layer has an average dry thickness (T m ), and contains many average intermediate pore diameters (D m ) is at least 20 nm and up to and including 60 nm of the intermediate micropores, wherein D m Greater than D o , D o Greater than D i , and the average dry thickness of the outer layer of aluminum oxide (T o ) is less than 150nm.

[0219] 12. The lithographic printing plate precursor of any of embodiments 1 to 11, wherein the on-press developable negative-working infrared radiation-sensitive layer further comprises (d) one or more polymeric binders, at least one of which is in particulate form.

[0220] 13. The lithographic printing plate precursor of any of embodiments 1-12, wherein the press-developable negative-working infrared radiation-sensitive imageable layer is the outermost layer.

[0221] 14. A lithographic printing plate precursor of any of embodiments 1-13, wherein there is (2) one or more hydrophilic polymers, and it includes a hydrophilic polymer comprising the following repeating units: repeating units comprising one or more of a carboxylic acid group, a carboxylate salt or a carboxylate ester group, wherein the repeating units account for at least 50 mol% of all repeating units.

[0222] 15. A lithographic printing plate precursor according to any of embodiments 1 to 14, wherein (2) one or more hydrophilic polymers are present and include hydrophilic polymers comprising the following repeating units: repeating units comprising carboxylic acid, phosphonic acid or phosphoric acid groups; and repeating units comprising amide groups.

[0223] 16. A method for providing a lithographic printing plate, comprising:

[0224] imagewise exposing the lithographic printing plate precursor of any of embodiments 1-15 to imagewise infrared radiation to form an imageable layer having imagewise infrared radiation exposed areas and unexposed areas, and

[0225] The unexposed areas are removed on-press from the imageable layer imagewise exposed to infrared radiation using a lithographic ink, a fountain solution, or both a lithographic ink and a fountain solution to form a lithographic printing plate.

[0226] 17. A method for preparing a lithographic printing plate precursor according to any of embodiments 1 to 15, comprising, in order:

[0227] A) providing an aluminum-containing plate having an electrochemically or mechanically grained and etched surface;

[0228] B) applying a first anodizing treatment to the aluminum-containing plate to form an aluminum oxide outer layer on the electrochemically or mechanically grained and etched surface, the aluminum oxide outer layer comprising a plurality of average outer micropores having a diameter (D o ) of at least 12 nm and up to and including 50 nm of outer micropores, and having an average dry thickness (T of at least 20 nm and up to and including 650 nm) o );

[0229] C) rinsing the outer layer of aluminum oxide;

[0230] D) subjecting the aluminum-containing plate to an additional anodizing treatment using sulfuric acid to form an inner aluminum oxide layer beneath the outer aluminum oxide layer, the inner aluminum oxide layer having an average dry thickness (T i ), and contains many average inner pore diameters (D i ) is an inner micropore of less than or equal to 11 nm, wherein the inner layer of aluminum oxide comprises aluminum sulfate;

[0231] E) rinsing the outer aluminum oxide layer and the inner aluminum oxide layer;

[0232] F) providing a hydrophilic layer over the outer layer of aluminum oxide, wherein the hydrophilic layer comprises: (1) one or more phosphorus-containing compounds having a C1 dry coverage and represented by the following formula (I):

[0233]

[0234] Wherein n is 0 or an integer from 1 to 10, -OM represents -OH or -OM + , and M + is a monovalent cation; and optionally (2) one or more hydrophilic polymers, which when present have a C2 dry coverage,

[0235] Where (1) the C1 dry coverage of one or more phosphorus-containing compounds is at least 50 mg / m 2 Up to and including 300 mg / m 2 , and when (2) one or more hydrophilic polymers are present, the ratio of C1 dry coverage to C2 dry coverage is at least 11:9; and

[0236] G) forming a negative-working infrared radiation-sensitive imageable layer that can be developed on-press over the outer aluminum oxide layer,

[0237] wherein the on-press developable negative-working infrared radiation-sensitive imageable layer comprises the following components (a) to (c) and optionally component (d):

[0238] (a) one or more free radical polymerizable components;

[0239] (b) an initiator composition that provides free radicals when the on-press developable negative-working infrared radiation-sensitive imageable layer is exposed to image-wise infrared radiation;

[0240] (c) one or more infrared radiation absorbers comprising an anionic chromophore having a net negative charge or an acidic group; and optionally (d) one or more polymeric binders, all of which are different from all of components (a), (b) and (c).

[0241] 18. The method of embodiment 17, wherein the first anodizing treatment is performed using phosphoric acid.

[0242] 19. The method of embodiment 17 or 18, further comprising between step C) and step D):

[0243] C') applying a second anodizing treatment to the aluminum-containing plate to form an aluminum oxide intermediate layer under the aluminum oxide outer layer, the aluminum oxide intermediate layer having an average dry thickness (T of at least 60 nm and up to and including 300 nm) m ), and contains many average intermediate pore diameters (Dm ) is at least 20 nm and up to and including 60 nm of the intermediate micropores, wherein D m Greater than D o , D o Greater than D i , and the average dry thickness of the outer layer of aluminum oxide (T o ) is less than 150nm, and

[0244] C") rinsing the outer aluminum oxide layer and the middle aluminum oxide layer, and

[0245] The additional anodizing treatment of step D) is a third anodizing treatment for forming an inner layer of aluminum oxide below the intermediate layer of aluminum oxide.

[0246] 20. The method of embodiment 17, wherein (2) one or more hydrophilic polymers are present in the hydrophilic layer, and it includes a hydrophilic polymer comprising the following repeating units: a repeating unit comprising a carboxylic acid, phosphonic acid or phosphoric acid group; and optionally a repeating unit comprising an amide group.

[0247] 21. The method of embodiment 17, wherein (2) one or more hydrophilic polymers are present in the hydrophilic layer and the ratio of C1 dry coverage to C2 dry coverage is at least 11:9 and up to and including 30:1.

[0248] The following examples are provided to illustrate the practice of the present invention and are not intended to be limiting in any way. Inventive Examples 1-16 and Comparative Examples 1-8:

[0249] The type A aluminum-containing substrate and the type B aluminum-containing substrate used for preparing the negative-working infrared radiation-sensitive lithographic printing plate precursors of the inventive and comparative examples were prepared according to the general method described above.

[0250] A-type support:

[0251] This aluminum-containing support was prepared like the aluminum-containing substrate of Inventive Example 1 described in US Pat. No. 10,363,734 (noted above). Thus, the Type A support had an inner layer of aluminum oxide and an outer layer of aluminum oxide.

[0252] B-type support:

[0253] This aluminum-containing support is prepared as a Type 3 aluminum-containing substrate (or "support") described in U.S. Serial No. 17 / 189,497 filed on March 2, 2021 (now published as U.S. Patent Application 2022 / 0194112A1 (noted above). Thus, a Type B support has an inner layer of aluminum oxide, an intermediate layer of aluminum oxide, and an outer layer of aluminum oxide.

[0254] Synthesis of copolymer for hydrophilic layer:

[0255] Polymer 1, a copolymer derived from vinylphosphonic acid and acrylamide (molar ratio 1:9), was prepared as follows:

[0256] 3500 g of ethanol was charged into a 10-liter reaction vessel equipped with a condenser and heated at 70° C. 231.1 g of vinylphosphonic acid monomer and 1368.9 g of acrylamide monomer were mixed into 1000 g of ethanol, and 52 g of commercially available azobisisobutyronitrile (AIBN) polymerization initiator was dissolved into the monomer mixture. This monomer mixture containing AIBN was then added dropwise to the 10-liter reaction vessel at 70° C. over a 4-hour period. After the addition, the resulting reaction mixture was kept at 70° C. for 2 hours and then cooled to room temperature. The resulting polymer 1 copolymer was precipitated as a white powder, which was separated by filtration and washed with 1 liter of ethanol. The polymer yield was determined to be 1550 g.

[0257] Preparation of hydrophilic layer formulation:

[0258] The hydrophilic layer formulations used in the various working examples were prepared with the components described in Table I below.

[0259] Table I: Hydrophilic layer formulation

[0260]

[0261] Table I (continued)

[0262] Components (g) SL-8 SL-9 SL-10 SL-11 SL-12 <![CDATA[ACUMER TM 1000 polymers*]]> 0.30 0.20 0.20 0.20 0.20 85% Phosphoric acid 0.88 0.88 0.88 0.88 0.88 Sodium hydroxide 0 0.10 0 0 0 Potassium hydroxide 0 0 0.10 0 0 28% ammonia solution 0 0 0 0.36 0 Monoethanolamine 0 0 0 0 0.10 <![CDATA[Takesurf TM D-410-GL]]> 0.05 0.05 0.05 0.05 0.05 Deionized water 98.77 98.77 98.77 98.51 98.77 total 100.00 100.00 100.00 100.00 100.00 <![CDATA[Dry coverage of phosphoric acid in the hydrophilic layer (mg / m 2 )]]> 150.00 150.00 150.00 150.00 150.00 <![CDATA[Dry coverage of the hydrophilic polymer in the resulting hydrophilic layer (mg / m 2 )]]> 30 20 20 20 20

[0263] Table I (continued)

[0264] Components (g) SL-13 SL-14 SL-15 SL-16 SL-17 <![CDATA[ACUMER TM 1000 polymers*]]> 0.20 0.20 0.20 0 0 Polymer 1 0 0 0 0.10 0.10 85% Phosphoric acid 2.35 0.15 0.15 2.35 0.15 Sodium hydroxide 0 0 0.02 0 0 <![CDATA[Takesurf TM D-410-GL]]> 0.05 0.05 0.05 0.05 0.05 Deionized water 97.40 99.60 99.58 97.50 99.70 total 100.00 100.00 100.00 100.00 100.00 <![CDATA[Dry coverage of phosphoric acid in the hydrophilic layer (mg / m 2 )]]> 400.00 25.00 25.00 400.00 25.00 <![CDATA[Dry coverage of the hydrophilic polymer in the resulting hydrophilic layer (mg / m 2 )]]> 20 20 20 20 20

[0265] ACUMER TM 1000 polymer is an aqueous solution of polyacrylic acid (50 wt%) obtained from Dow Chemical Company. TM D-410-GL is a leveling agent obtained from TAKEMOTO OIL&FAT CO., LTD.

[0266] Use a wire-wound coating rod at 20 g / m 2 Each hydrophilic layer formulation shown in Table I was coated onto a Type A support sample or a Type B support sample. The resulting aluminum-containing substrates were each dried at 80° C. for 2 minutes. The dry coverage of each dried hydrophilic layer is shown in Table I above.

[0267] Preparation of negative-working infrared radiation-sensitive precursors that can be developed on-press:

[0268] Coating formulations MC-1, MC-2 and MC-3 of negative-working infrared radiation-sensitive imageable layers that can be developed on press were prepared using the components and amounts shown in Table II below and were dissolved or dispersed at a total solids content of 5 wt % in a coating solvent mixture of 35 wt % n-propanol, 20 wt % 2-methoxypropanol, 35 wt % 2-butanone and 10 wt % water.

[0269] The starting materials identified in Table II below can be obtained from one or more commercial sources of chemicals or prepared using known synthetic methods and starting materials. Other materials are described in Table III below.

[0270] Table II

[0271]

[0272] Table III

[0273]

[0274] These formulations were coated onto an aluminum-containing substrate comprising a hydrophilic layer using a wire-wound coating rod and dried at 80° C. for 2 minutes to provide press-developable negative-working infrared radiation-sensitive image-recording layers each having a 1 g / m 2 The resulting lithographic printing plate precursors are shown in Table IV below.

[0275] Table IV

[0276] Support Hydrophilic layer Negative-working infrared radiation sensitive layer that can be developed on-press Invention Example 1 Type A SL-1 MC-1 Invention Example 2 Type A SL-2 MC-1 Invention Example 3 Type A SL-3 MC-1 Invention Example 4 Type A SL-4 MC-1 Invention Example 5 Type A SL-5 MC-1 Invention Example 6 Type A SL-6 MC-1 Invention Example 7 Type A SL-7 MC-1 Invention Example 8 Type A SL-8 MC-1 Invention Example 9 Type A SL-9 MC-1 Invention Example 10 Type A SL-10 MC-1 Invention Example 11 Type A SL-11 MC-1

[0277] Table IV - continued

[0278] Invention Example 12 Type A SL-12 MC-1 Invention Example 13 Type B SL-1 MC-1 Invention Example 14 Type B SL-6 MC-1 Invention Example 15 Type A SL-1 MC-2 Invention Example 16 Type A SL-6 MC-2 Comparative Example 1 Type A SL-13 MC-1 Comparative Example 2 Type A SL-14 MC-1 Comparative Example 3 Type A SL-15 MC-1 Comparative Example 4 Type A SL-16 MC-1 Comparative Example 5 Type A SL-17 MC-1 Comparative Example 6 Type A SL-1 MC-3 Comparative Example 7 Type B SL-13 MC-1 Comparative Example 8 Type B SL-14 MC-1

[0279] Using a Kodak Magnus 800 imagesetter and 150 mJ / cm in solid areas 2 Each of the lithographic printing plate precursors identified above is imaged with an exposure energy of .

[0280] The following evaluations were performed on each imaged precursor or the corresponding non-imaged precursor.

[0281] On-press development capability (DOP):

[0282] Each lithographic printing plate precursor was imaged as indicated above, and then mounted on a Roland R-201 printing press for on-press development. The printing press was supplied with a fountain solution [Presarto WS 100 (sold by DIC Graphics) / isopropyl alcohol / water 1 / 1 / 98 (volume ratio)], an S-7400 rubber blanket (Kin-yo-sha), OK top-coated paper matte N-grade paper (Oji paper) as printing paper, and a lithographic printing ink (Fusion G Magenta N sold by DIC Graphics), and printing was performed at a printing rate of 9,000 sheets / hour. The on-press developability was evaluated by the number of printed sheets (or impressions) from which no ink transfer was observed in the non-imaged areas.

[0283] The DOP was evaluated using the following two types of lithographic printing plates. A sample of each lithographic printing plate precursor was packed with light-shielding paper immediately after production and stored at 25° C. for 7 days (in the case of identification as 'NK7'). In addition, a sample of each lithographic printing plate precursor was stored in a commercially available humidity chamber ETAC FX-430 at 40° C. and 80% RH for 7 days (in the case of identification as 'HT7').

[0284] In this evaluation, a DOP of less than 50 sheets (prints) is preferred, and a DOP of more than 100 sheets (prints) is unacceptable for this press condition. The smaller the numerical difference between the DOP in the case identified as NK7 and the DOP in the case identified as HT7, the better the stability of the precursor over time after manufacture.

[0285] Plate run strength without ozone exposure:

[0286] Each lithographic printing plate precursor was imaged as described above, and the resulting imaged precursor was mounted on a Komori S-26 printing press at 8,000 rpm, and the plate run was evaluated using a mixture of 1% K701 (DIC Graphics) and 10% isopropyl alcohol in water as a fountain solution, a rubber blanket S-7400 (Kin-yo-sha), OK Top Coat Paper Matt N Grade Paper (Oji Paper) as printing paper, and K Magenta N Grade lithographic printing ink (DIC Graphics).

[0287] When the number of printed sheets (copies or impressions) increases by continuous printing, the negative-working infrared radiation-sensitive imaging layer of the lithographic printing plate, which can be developed on the press, gradually wears away and its ink receptivity deteriorates. As a result, the ink density on the printed sheets decreases. The plate run is determined as the number of copies (or impressions) at which the reflection density of the solid areas on the printed sheets obtained decreases to 90% of that at the start of printing. The greater the number of copies (or impressions) at which this deterioration occurs, the better the plate run.

[0288] Plate run strength with ozone exposure:

[0289] Prior to imaging, each lithographic printing plate precursor was exposed to a controlled amount of ozone within a commercial humidity chamber ETAC FX-430, where the ozone concentration was controlled at 1 ppm and the chamber temperature was controlled at 25° C. The following equipment was used to control the ozone concentration:

[0290] Kotohira portable ozone generator KPO-T01 as an ozone source;

[0291] Kanomax Gasmaster Model 2750 as an ozone monitor.

[0292] The ozone exposure time for each precursor was 6 hours, equivalent to an ozone exposure dose of 21,600 ppm·s (wherein "ppm" is the unit of ozone concentration in parts per million by volume, and "s" is an abbreviation for the time unit second). After this exposure to ozone, each precursor was imaged and the plate run was evaluated as described above for the precursors that were not exposed to ozone.

[0293] The results of all of these evaluations are shown in Table V below.

[0294] Table V

[0295]

[0296] Table V - continued

[0297] Comparative Example 2 40 ＞1000 ＞1000 100,000 90，000 Comparative Example 3 45 ＞1000 ＞1000 100,000 90，000 Comparative Example 4 25 30 5 ＜1,000 ＜1,000 Comparative Example 5 40 ＞1000 ＞1000 100,000 90，000 Comparative Example 6 30 30 0 90,000 5，000 Comparative Example 7 25 30 5 ＜1,000 ＜1,000 Comparative Example 8 40 ＞1000 ＞1000 90,000 80，000

[0298] As can be seen from the results shown in Table V, the precursors of Inventive Examples 1 to 16 containing anionic IR dyes and inventive aluminum-containing substrates exhibited desirably fast on-press development and small DOP differences from the imaged precursors for the case labeled NK7 and the imaged precursors for the case labeled HT7. These inventive precursors exhibited long imaged plate runs regardless of whether the unimaged precursors were exposed to ozone.

[0299] Although the precursors of Comparative Examples 1, 4 and 7 contain anionic IR dyes, they contain aluminum-containing substrates outside the scope of the present invention because the dry coverage of phosphoric acid in the hydrophilic layer is greater than 300 mg / m 2 They exhibited desirably fast on-press development from the imaged precursors labeled NK7, the imaged precursors labeled HT7, and a small DOP gap, regardless of whether the unimaged precursors were exposed to ozone, and these comparative precursors exhibited poor plate runs.

[0300] Although the precursors of Comparative Examples 2, 3, 5 and 8 contain anionic IR dyes, they contain aluminum-containing substrates outside the scope of the present invention because the dry coverage of phosphoric acid in the hydrophilic layer is less than 50 mg / m 2 The unimaged precursors exhibited long plate runs regardless of whether they were exposed to ozone, but they exhibited extremely slow post-HT7 on-press development and large DOP gaps. Such extremely slow post-HT7 on-press development is believed to result from the reaction of the anionic chromophores of the infrared radiation absorber in the negative-working infrared radiation imageable layer that can be developed on-press with the aluminum ions Al of aluminum sulfate released from the anodic layer of the inventive substrate during storage of the precursors under HT7 conditions. 3+ The salts between them form salts.

[0301] The precursors of Comparative Example 6 contained a cationic dye and an aluminum-containing substrate according to the present invention. However, while the precursors exhibited desirably fast on-press development for the case identified as NK7 and on-press development for the case identified as HK7, and a small DOP gap, and they exhibited long plate runs if the unimaged precursors were not exposed to ozone, they exhibited poor plate runs if they were exposed to ozone prior to imaging.

Claims

1. A lithographic printing plate precursor comprising: an aluminum-containing substrate having a hydrophilic surface, and a press-developable, negative-working, infrared radiation-sensitive imageable layer disposed over the hydrophilic surface of the aluminum-containing substrate, wherein the aluminum-containing substrate comprises: an aluminum-containing plate having a ground and etched surface; an inner layer of aluminum oxide disposed on the grained and etched surface, the inner layer of aluminum oxide having an average dry thickness (Ti) of at least 300 nm and up to and including 3000 nm and comprising a plurality of inner micropores having an average inner micropore diameter (Di) less than or equal to 11 nm, wherein the inner layer of aluminum oxide comprises aluminum sulfate; An outer aluminum oxide layer is disposed above the inner aluminum oxide layer, the outer aluminum oxide layer comprising a plurality of pores having an average outer diameter (D o ) of at least 12 nm and up to and including 50 nm of outer micropores, and having an average dry thickness (T of at least 20 nm and up to and including 650 nm) o );and A hydrophilic layer disposed on the alumina outer layer, wherein the hydrophilic layer comprises: (1) one or more phosphorus-containing compounds having a C1 dry coverage and represented by the following formula (I): wherein n is 0 or an integer from 1 to 10, and -OM represents -OH or -OM + , and M + is a monovalent cation; and optionally (2) one or more hydrophilic polymers, which when present have a C2 dry coverage, wherein the C1 dry coverage of the (1) one or more phosphorus-containing compounds is at least 50 mg / m 2 Up to and including 300 mg / m 2 , and when said (2) one or more hydrophilic polymers are present, the ratio of said C1 dry coverage to said C2 dry coverage is at least 11:9; and The on-press developable negative-working infrared radiation-sensitive imageable layer comprises the following components (a) to (c) and optionally component (d): (a) one or more free radical polymerizable components; (b) an initiator composition that provides free radicals when the on-press developable negative-working infrared radiation-sensitive imageable layer is exposed to image-wise infrared radiation; (c) one or more infrared radiation absorbers comprising an anionic chromophore having a net negative charge or an acidic group; and optionally (d) one or more polymeric binders, all of which are different from all of components (a), (b) and (c).

2. The lithographic printing plate precursor of claim 1, wherein the C1 dry coverage is at least 75 mg / m 2 Up to and including 200 mg / m 2 .

3. The lithographic printing plate precursor of claim 1 or 2, wherein the ratio of the C1 dry coverage to the C2 dry coverage is at least 11:9 and up to and including 30:

1.

4. The lithographic printing plate precursor of any one of claims 1 to 3, wherein the (c) one or more infrared radiation absorbers are present in an amount of at least 10 mg / m 2 Up to and including 200 mg / m 2 A dry coverage of is present in the on-press developable negative-working infrared radiation-sensitive imageable layer.

5. The lithographic printing plate precursor of any one of claims 1 to 4, wherein the (2) one or more hydrophilic polymers are present in the hydrophilic layer, and the (2) one or more hydrophilic polymers include a hydrophilic polymer comprising the following repeating units: repeating units comprising carboxylic acid, phosphonic acid, phosphoric acid groups, or salts or esters of any of these acids; and optionally repeating units comprising amide groups.

6. The lithographic printing plate precursor of any one of claims 1 to 5, wherein M + Independently selected from the group consisting of protons, sodium cations, potassium cations, ammonium cations, alkylammonium cations, dialkylammonium cations, trialkylammonium cations, and tetraalkylammonium cations, wherein each alkyl group is optionally substituted.

7. A lithographic printing plate precursor as described in any of claims 1-6, wherein the -OM group is selected so that the (1) one or more phosphorus-containing compounds represented by formula (I) exhibit a pH of at least 1 and up to and including 10 when dissolved in an aqueous solution containing 5 weight % of the (1) one or more phosphorus-containing compounds represented by formula (I).

8. The lithographic printing plate precursor of any one of claims 1 to 7, wherein the anionic chromophore having a net negative charge or an acidic group is represented by the following formula (II): in: Each X independently represents >S, >O, >NR or >C(R)2; Each R 1 is independently optionally substituted alkyl; R 2 represents hydrogen, halogen, -SR, -SO2R, -OR or -NR2 group; Each R 3 independently represents a hydrogen atom, an optionally substituted alkyl group, -COO - , -COOR, -OR, -SR, -NR2, a halogen atom, a sulfonate group, or an optionally substituted benzo-fused ring; --- represents an optional five-membered carbocyclic ring or a six-membered carbocyclic ring; each R independently represents hydrogen, optionally substituted alkyl or optionally substituted aryl; each n is independently 0, 1, 2 or 3; and R 1 , R 2 and R 3 At least one comprises a sulfonate group, a carboxylate group, or both a sulfonate group and a carboxylate group to provide a net negative charge or an acidic group to formula (II).

9. The lithographic printing plate precursor of claim 8, wherein R 1 , R 2 and R 3 At least one comprises a carboxylate group to provide a net negative charge or acidic group to formula (II).

10. The lithographic printing plate precursor of any one of claims 1 to 9, wherein the outer layer of aluminum oxide has an average dry thickness (T o ), and the outer aluminum oxide layer is directly disposed on the inner aluminum oxide layer; the average dry thickness (Ti) of the inner aluminum oxide layer is at least 500 nm, and the average inner micropore diameter (Di) is less than or equal to 11 nm and less than the average outer micropore diameter (D o ).

11. The lithographic printing plate precursor of any one of claims 1 to 10, wherein the aluminum-containing substrate further comprises an aluminum oxide intermediate layer disposed between the aluminum oxide inner layer and the aluminum oxide outer layer, wherein the aluminum oxide intermediate layer has an average dry thickness (T ) of at least 60 nm and up to and including 300 nm. m ), and contains many average intermediate pore diameters (D m ) is at least 20 nm and up to and including 60 nm of the intermediate micropores, wherein D m Greater than D o , D o Greater than D i , and the average dry thickness of the aluminum oxide outer layer (T o ) is less than 150nm.

12. The lithographic printing plate precursor of any one of claims 1 to 11, wherein the on-press developable negative-working infrared radiation-sensitive layer further comprises said (d) one or more polymeric binders, at least one of which is in particulate form.

13. The lithographic printing plate precursor of any of claims 1 to 12, wherein the press-developable negative-working infrared radiation-sensitive imageable layer is the outermost layer.

14. A lithographic printing plate precursor as described in any one of claims 1 to 13, wherein the (2) one or more hydrophilic polymers are present and include a hydrophilic polymer comprising the following repeating units: a repeating unit comprising one or more of a carboxylic acid group, a carboxylate salt or a carboxylate ester group, wherein the repeating unit accounts for at least 50 mol% of all repeating units.

15. The lithographic printing plate precursor described in any one of claims 1 to 14, wherein the (2) one or more hydrophilic polymers are present and include hydrophilic polymers comprising the following repeating units: repeating units comprising carboxylic acid, phosphonic acid or phosphoric acid groups; and repeating units comprising amide groups.

16. A method for providing a lithographic printing plate, comprising: imagewise exposing the lithographic printing plate precursor of any one of claims 1 to 15 to imagewise infrared radiation to form an imageable layer having imagewise infrared radiation exposed areas and unexposed areas, and The unexposed areas are removed on-press from the imagewise infrared radiation exposed imageable layer using a lithographic ink, a fountain solution, or both a lithographic ink and a fountain solution to form a lithographic printing plate.

17. A method for preparing a lithographic printing plate precursor according to any one of claims 1 to 15, comprising, in order: A) providing an aluminum-containing plate having an electrochemically or mechanically grained and etched surface; B) subjecting the aluminum-containing plate to a first anodizing treatment to form an aluminum oxide outer layer on the electrochemically or mechanically grained and etched surface, wherein the aluminum oxide outer layer comprises a plurality of average outer micropores having a diameter (D o ) of at least 12 nm and up to and including 50 nm of outer micropores, and having an average dry thickness (T of at least 20 nm and up to and including 650 nm) o ); C) rinsing the outer layer of aluminum oxide; D) subjecting the aluminum-containing plate to an additional anodizing treatment using sulfuric acid to form an inner aluminum oxide layer beneath the outer aluminum oxide layer, the inner aluminum oxide layer having an average dry thickness (T of at least 300 nm and up to and including 3000 nm) i ), and contains many average inner pore diameters (D i ) inner micropores less than or equal to 11 nm, wherein the inner alumina layer comprises aluminum sulfate; E) rinsing the outer aluminum oxide layer and the inner aluminum oxide layer; F) providing a hydrophilic layer over the outer layer of aluminum oxide, wherein the hydrophilic layer comprises: (1) one or more phosphorus-containing compounds having a C1 dry coverage and represented by the following formula (I): wherein n is 0 or an integer from 1 to 10, and -OM represents -OH or -OM + , and M + is a monovalent cation; and optionally (2) one or more hydrophilic polymers, which when present have a C2 dry coverage, wherein the C1 dry coverage of the (1) one or more phosphorus-containing compounds is at least 50 mg / m 2 Up to and including 300 mg / m 2 , and when said (2) one or more hydrophilic polymers are present, the ratio of said C1 dry coverage to said C2 dry coverage is at least 11:9; and G) forming a negative-working infrared radiation-sensitive imageable layer that can be developed on-press over the outer aluminum oxide layer, wherein the on-press developable negative-working infrared radiation-sensitive imageable layer comprises the following components (a) to (c) and optionally component (d): (a) one or more free radically polymerizable components; (b) an initiator composition that provides free radicals when the on-press developable negative-working infrared radiation-sensitive imageable layer is exposed to image-wise infrared radiation; (c) one or more infrared radiation absorbers comprising an anionic chromophore having a net negative charge or an acidic group; and optionally (d) one or more polymeric binders, all of which are different from all of components (a), (b) and (c).

18. The method of claim 17, wherein the first anodizing treatment is performed using phosphoric acid.

19. The method of claim 17 or 18, further comprising between step C) and step D): C') subjecting the aluminum-containing plate to a second anodizing treatment to form an aluminum oxide intermediate layer beneath the aluminum oxide outer layer, the aluminum oxide intermediate layer having an average dry thickness (T of at least 60 nm and up to and including 300 nm) m ), and contains many average intermediate pore diameters (D m ) is at least 20 nm and up to and including 60 nm of the intermediate micropores, wherein D m Greater than D o , D o Greater than D i , and the average dry thickness of the aluminum oxide outer layer (T o ) is less than 150nm, and The additional anodizing treatment of step D) is a third anodizing treatment for forming the inner aluminum oxide layer below the intermediate aluminum oxide layer.

20. The method of any one of claims 17-19, wherein the (2) one or more hydrophilic polymers are present in the hydrophilic layer and include a hydrophilic polymer comprising the following repeating units: a repeating unit comprising a carboxylic acid, phosphonic acid or phosphoric acid group; and optionally a repeating unit comprising an amide group.

21. The method of any one of claims 17-20, wherein the (2) one or more hydrophilic polymers are present in the hydrophilic layer and the ratio of the C1 dry coverage to the C2 dry coverage is at least 11:9 and up to and including 30:1.

Images