Risograph printing machine setup method

Abstract

A method for setting up a lithographic printing press is provided that allows for a reduction in the amount of wasted copies generated during press set-up time. The method provides for the use of paper that has already been used in the press set-up process of a previous print run and that includes a first color bar. The method includes exposing a second color bar on the printed copy at a location different from the location of the first color bar.

Description

[Technical Field]

[0001] The present invention relates to an improved method for starting up and regulating a lithographic press to the point where it produces saleable copies. [Background technology]

[0002] Lithographic printing typically involves the use of a printing master, such as a printing plate, mounted on the cylinder of a sheet-fed or web press. The master carries a lithographic image on its surface, and a print is obtained by applying ink to the image and then transferring the ink from the master to a receiver material, typically paper. In traditional lithographic printing, ink and an aqueous liquid called a dampening fluid are applied to a lithographic image, which consists of oleophilic (or hydrophobic, i.e., ink-accepting, water-repelling) and hydrophilic (or oleophobic, i.e., water-accepting, ink-repelling) areas. In offset printing, the lithographic plate is mounted on a plate cylinder, onto which ink and dampening fluid are applied by the press's inking and dampening units, and the ink accepted by the lithographic image is transferred to an ink-receptive material, such as paper, via an intermediate support called a blanket cylinder. The only exception to the above principles is dry lithographic (also called waterless) printing. This printing technique requires a special type of plate, whose coating is primarily silicone. Silicone is so ink repellent that no water is needed to produce a good print.

[0003] Lithographic printing masters are generally obtained by image-wise exposure and processing of a printing plate (also called "plate material" or simply "plate") having a light- or heat-sensitive coating on a substrate. The printing plate coating is image-wise exposed to heat or light, typically by a digitally modulated exposure device such as a laser, which triggers (physico-)chemical processes such as ablation, polymerization, insolubilization by cross-linking of polymers or particle aggregation of thermoplastic polymer latexes, solubilization by breaking intermolecular interactions or increasing the permeability of a development barrier layer.

[0004] Although some printing plates are capable of producing a lithographic image immediately after exposure, the most common plate materials require wet processing with a developer because exposure creates a difference in the solubility or dissolution rate of the developer between the exposed and unexposed areas of the coating. In a positive-working printing plate, the exposed areas of the coating dissolve in the developer, while the unexposed areas remain resistant to the developer. In a negative-working printing plate, the unexposed areas of the coating dissolve in the developer, while the exposed areas remain resistant to the developer.

[0005] Most lithographic master plates have a hydrophobic coating on a hydrophilic support, so that the areas that remain resistant to the developer define the ink acceptance. Hence, the printing areas of the plate, which are on a hydrophilic support, are revealed by the dissolution of the coating in the developer in the non-printing areas.

[0006] Some thermal processes allow for plate making without wet processing, for example, by ablation of one or more layers of a coating. In the exposed areas, the surface of the underlying layer is revealed, which has a different affinity for ink or fountain solution than the surface of the unexposed coating; image (printing) areas and non-image or background (non-printing) areas are obtained.

[0007] Most common heat-sensitive (thermal) printing plates create an image between exposed and unexposed areas of a coating by heat-induced differential solubility of an alkaline developer. The coating typically contains an oleophilic binder (e.g., a phenolic resin) whose solubility in the developer either decreases (negative-working) or increases (positive-working) upon imagewise exposure. During processing, the solubility difference results in the removal of the non-image (non-printing) areas of the coating, thereby revealing the hydrophilic support, while the image (printing) areas of the coating remain on the support. Typical examples of such plates are described, for example, in U.S. Patent Nos. 5,629,299; 5,729,333; 5,729,343; 5,729,353; 5,729,363; and 5,729,363. Negative-working embodiments of such thermal materials often require a preheating step between exposure and development, as described, for example, in U.S. Patent No. 5,629,299.

[0008] Negative-working heat-sensitive (thermal) printing plates that do not require a preheating step can have an image-recording layer that operates by heat-induced particle coalescence of thermoplastic polymer particles, as described, for example, in U.S. Patent Nos. 5,119,229, 5,149,929, 5,163,997, and 5,172,166. These patents disclose methods for making lithographic printing plates, comprising the steps of: (1) imagewise exposing a plate master having a heat-sensitive image-recording layer, the image-recording layer containing hydrophobic thermoplastic polymer particles (sometimes referred to as latex particles), dispersed in a hydrophilic binder, to infrared radiation; and (2) developing the imagewise exposed element. During the development step, the unexposed areas of the image-recording layer are removed from the support, while the latex particles in the exposed areas coalesce to form a hydrophobic phase that is not removed during the development step. It is known in the art that the lithographic plate obtained after exposure, development, and optional gumming can be heat-treated in a so-called overprinting process to increase the plate's printing life on a printing press. Typical plate printing is carried out by heating the plate in an oven at high temperatures, for example about 250° C., as described, for example, in US Pat. No. 5,629,999.

[0009] Another common type of lithographic printing plate master is the so-called photopolymer printing plate, which typically includes a negative-working image-recording layer and often a protective overcoat. When imagewise exposed to light or heat, the image-recording layer undergoes a chemical reaction, hardening the layer, i.e., becoming insoluble or non-dispersible in developer solutions through photopolymerization and / or photocrosslinking. Photopolymer plates that operate by free radical polymerization or crosslinking typically have an overcoat that also functions as an oxygen barrier layer, increasing the sensitivity of the plate by reducing oxygen quenching of free radicals generated in the image-recording layer upon imagewise exposure. The overcoat also protects the image-recording layer from scratches and / or contamination.

[0010] The conventional method of making a photopolymer printing plate involves first imagewise exposing the plate with a laser, followed by an optional "preheat" step to enhance the polymerization and / or crosslinking reaction of radicals generated in the image-recording layer by the exposure, a washing step to remove the protective overcoat, an alkaline development step to remove the unexposed areas of the image-recording layer, and a rinsing and gumming step.

[0011] An important trend in lithographic platemaking is related to ecology and sustainability. Systems and methods that allow for low consumption of processing liquids such as developer, rinse water, and gum solution, or that allow processing using aqueous developers that are free of hazardous chemicals and / or have a pH close to 7 (neutral developer), are attracting much attention in the market. An advantageous and increasingly common method involves the use of gum solution as developer, whereby the plate is developed and gummed in a single step, as described, for example, in US Pat. No. 5,629,997 and US Pat. No. 5,629,997.

[0012] More recently, on-press processing, in which the plate is mounted on a printing press and the image is developed by interaction with ink and / or dampening fluid supplied to the plate during press start-up, has gained market attention. Plate masters designed specifically for on-press processing are sometimes designated "processless" or "DOP" (Development On Press) plates. During press start-up, DOP plates develop the lithographic image by allowing the non-printing areas of the coating to be removed by the ink and / or dampening fluid, while the printing areas remain resistant to them.

[0013] In a typical printing process, lithographic printing plates for each color selection, typically cyan, magenta, yellow, and black (CMYK), are attached to the plate cylinder of a corresponding printing station on the press. The press operator can adjust the amount of ink dispensed across the width of the plate cylinder by adjusting the ink keys at each printing station during a process known as "press setup." Setup is a term that defines all the operations required to set up and configure a printing press to the point where it produces sellable copies. Installing a new printing plate set and tuning the press for a print run can take several minutes, depending on the degree of automation of the particular press and the skill of the operator. As a result, a significant number of printed copies are lost during the press setup process; this number typically amounts to several hundred, and in some print runs, for example, when using UV-curable inks, it can even exceed 500.

[0014] There is a growing interest in the market to reduce the large amount of waste copies, both from an economic and ecological standpoint, and also in light of competition from digital printing techniques such as inkjet printers that produce production-quality, immediate prints. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] EP625728 [Patent Document 2] EP823327 [Patent Document 3] EP825927 [Patent Document 4] EP864420 [Patent Document 5] EP894622 [Patent Document 6] EP901902 [Patent Document 7] EP770494 [Patent Document 8] 770495 [Patent Document 9] 770496 [Patent Document 10] 770497 [Patent Document 11] EP1 506 854 [Patent Document 12] EP1 342 568 [Patent Document 13] WO 2005 / 111727 Summary of the Invention

[0016] An object of the present invention therefore relates to a method for setting up a lithographic printing press for a new print run, which method results in a significant reduction in the number of wasted copies. This object is achieved by a method as defined in claim 1, i.e. a method for setting up a lithographic printing press for a new print run, in which sheets are reused that have already been printed in the process of preparing the press for printing a previous print run, and therefore typically contain an image and at least one color bar. As a result, much less paper is wasted during the printing process of at least two print runs. The method comprises the following steps: (a) preparing a printing plate blank by exposing an image in an area of ​​a lithographic printing plate blank and color bar CB-02 outside that area; (b) mounting the exposed master on a plate cylinder of a printing press; (c) performing a setup process for the printing press to bring it to the production quality defined by the target color data on the printed copies produced by the printing press, the printing press setup process including the steps of: (ci) feeding the multiple sheets through a printing press, thereby producing printed copies of the image and color bar CB-02; (c-ii) measuring color data of a color bar on the printed copy, and adjusting the inking device according to the difference between the measured color data and the target color data; (c-iii) repeating steps (ci and c-ii) until the measured color data matches the target color data; and Including, In this method, the sheet fed through the printing press in step (ci) is a sheet that has already been used in the press setup process for another printing run and that contains at least a previous color bar CB-01 in a position on the printed copy that is different from the position of the color bar CB-02 that is exposed in step (a).

[0017] Color bars CB-01 and CB-02 are preferably printed on the same side of the sheet.

[0018] Other features, elements, steps, characteristics, and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, which are also defined in the appended claims. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 shows a printed sheet (1) obtained after two printing runs according to the method of the invention. [Figure 2] FIG. 1 shows a printed sheet (1) obtained after three printing runs according to the method of the invention. [Figure 3] 1 is a schematic illustration of four consecutive print runs using the same paper.

[0020] It should be noted that the drawings are presented as grayscale images due to the technical requirements of patent application documents, and therefore do not represent the full scope of the invention, since the invention can be used in black and white printing as well as in color printing. In the latter embodiment, the color bar contains multiple color patches to allow ink key adjustment for the various printing stations of the printing press. DETAILED DESCRIPTION OF THE INVENTION

[0021] Printing press setup process A printing press can be a monochrome press or a multicolor press with multiple color stations. Monochrome presses have at least one printing station, which includes an inking unit and a plate cylinder. Multicolor presses can have two to six or even up to twelve printing stations, but typically have four printing stations. Full-color printing requires the preparation of a lithographic plate for each color selection, typically cyan, magenta, yellow, and black (CMYK), and optionally other combinations. Each printing plate is attached to the plate cylinder of the corresponding printing station on the press. The press operator can adjust the amount of ink dispensed across the width of the plate cylinder by adjusting the ink keys at each printing station during a process known as "press setup." The press setup process includes all the operations required to set up and configure a lithographic press to produce saleable copies.

[0022] A typical inking unit of a lithographic printing press has a series of rollers that deliver ink from an ink reservoir to the plate. At the start of a printing run, the press must be adjusted to achieve production quality, i.e., the target color data, in the printed copies produced by the press. If the measured color and the target color are within a tolerance, e.g., the ΔE deviation as specified in ISO standard 12647-2 (2013), then the measured color data matches the target color data.

[0023] This color measurement process is preferably carried out by an automatic press control system, which makes it possible to measure the color data of the printed copies and to modify said color data of the printed copies by adjusting the inking units.

[0024] In fact, in traditional press setup procedures, initial ink key settings are selected according to a known relationship between the plate image (larger print areas require more ink) and ink supply rate and the resulting color density of the printed copy. This relationship depends on the specific combination of a given receiver material (e.g., paper (level of ink absorption, uncoated paper, coated paper, e.g., matte paper, glossy paper, silk paper, adhesive paper, etc.), cardboard, corrugated paper, vinyl, fabric, etc.), colorant type, screening type, and ink type (e.g., UV-curable ink, LED-curable ink, electron beam (EB)-curable ink, oxidative ink, etc.), which may be referred to as standard press conditions. Standard press conditions are usually collected by color measurements on a press carefully configured for that specific press condition and / or based on artificial intelligence. Despite these known relationships between ink supply and color density, inking unit adjustments are still required once the press is started up because each print run uses a different lithographic image. As a result, the press setup process involves additional fine-tuning of the ink supply for that particular image with the goal of obtaining a stable setting that results in a color density in the printed copy that matches the target color density, where matching means that the difference between the measured color and the target color is within an acceptable range, for example, the ΔE deviation specified in ISO standard 12647-2 (2013).

[0025] Ink key adjustment is typically controlled by measuring a color bar exposed outside the image area on the printing plate. Such a color bar typically consists of grayscale strips and color patches (often square), which are arranged side by side outside the printing area, e.g., perpendicular to the axis of the printing press's plate cylinder (in the feed direction) or along a direction parallel to the axis of the plate cylinder. The color bar is preferably arranged along a direction parallel to the axis of the plate cylinder. The color bar is preferably printed on the printed copy together with the image and can be measured after the print run of the printed copy by, for example, a press operator removing the printed copy from the press and measuring the color of the patches using a densitometer, by an off-press (digital) scanning device, and / or automatically by a digital scanning device or an automatic press control system installed on the press itself. Such an automatic press control system preferably includes an integrated system for detecting and measuring the color bar. The color bar preferably also includes predefined "patches," also referred to as "recognition patches," that allow a digital scanning device or an automatic press control system to locate the color bar on the printed copy in order to measure color data and adjust the inking unit. Such recognition patches include, for example, bar codes, QR codes, etc., which can be located anywhere on the color bar. The color bar can include one or more sets of recognition patches, for example, a separate set of recognition patches for each color, e.g., CMYK.

[0026] Alternatively, the detection of the color bar and / or color bar recognition patches by the automatic press control system can be based on specific conditions that define the location of the color bar on the printed sheet.

[0027] The measured color data can then be used to adjust the inking unit keys in order to modify the amount and lateral distribution of ink across the plate cylinder, and the procedure is repeated until production quality (sellable copies) are obtained. The color data can be density (color density) data or colorimetric (L * , a * , b * ) data. Examples of fully automated systems are described, for example, in US6024018 and US2006 / 0170996. will be done.

[0028] In accordance with the method of the present invention, a press set-up process for production quality includes reusing sheets already used in the press set-up process for one or more previous print runs, the sheets having at least one image and at least one color bar.

[0029] The method includes starting a print run by feeding multiple sheets through a printing press that have been used in at least one prior print run and therefore have at least one image and at least one color bar, producing printed copies that have: (i) at least one image printed in the prior print run and an image printed in the current print run, and (ii) at least two color bars: the color bar printed in the prior print run, also known as the "prior color bar" or CB-01, and the color bar printed in the current print run, also known as the "current color bar" or CB-02.

[0030] The color bar on the printed sheet that was used for the setup process in the previous print run must be neutralized before the color bar is detected by the printing press this time. Typically, the automatic press control system, which is the device that detects and measures the color bar, is installed at the end of the printing press, i.e., after the last printing station. This implies that the color bar that was printed in the previous print run and that must be neutralized before the color bar is detected this time must be neutralized at the end of the previous print run, i.e., on the press or off-press after the color bar measurement, or at any printing station during the current print run. Alternatively, an automatic press control system with an integrated system for detecting and measuring color bars can be implemented in the press as two separate devices: a detection device and a color measurement device. The detection device can be located anywhere between the beginning of the press, e.g., before the first printing station, and the end of the press, e.g., after the last printing station. The color measurement device is typically located after the last printing station of the press. In this embodiment, invalidation of the color bar printed in the previous print run can be done by either: (i) at any location on the printing press during the preceding printing run, i.e. at any printing station, such as a printing station applying PMS colors, varnishes, etc., or a printing station dedicated to color bar neutralization; provided that the color bar is detected by a detection device before its neutralization; or (ii) At any location on the press, i.e., at any printing station, during the current printing run, where the previous color bar is nullified before the current color bar is detected by the detection device.

[0031] The nullification of the (previous) color bar during a printing run is preferably carried out in step (a) by exposing an image (also referred to as a nullification image) on the printing plate at a position corresponding to the position of the (previous) color bar on the printed sheet. The nullification image can cover the entire color bar or at least a predetermined "recognition patch" of the color bar. The nullification image can have any pattern, for example, a longitudinal stroke, a group of cross-sections, a circle, a rectangle, a triangle, and / or an oval mark, and / or any other shape or figure. In an embodiment in which the printing press has, for example, four printing stations, the exposure of the nullification image is preferably carried out on one of the four printing plates prepared for each printing station at a position corresponding to the position of the printed color bar to be nullified. The (previous) color bar can be nullified at any printing station, for example, a printing station that applies PMS colors, varnish, etc., and / or by a nullification device, for example, an inkjet printhead. It can also be done by a device such as a dedicated color bar neutralization printing station that can be installed throughout the printing machine, but where the (previous) color bar is neutralized before the current color bar is detected.

[0032] 1 shows an example of a printed sheet (1) obtained after two printing runs according to the method of the present invention. The sheet (1) has printed copies of two images (3) printed in the first and second printing runs, respectively, inside the image area (2), as well as printed copies of two color bars (CB-1) and (CB-2) printed in the first and second printing runs, respectively, at positions (Y1) and (Y2) along the direction (X) parallel to the axis of the plate cylinder. One of the color bars is neutralized (CB-1': the apostrophe indicates neutralization) by a neutralization image (4) located above the printed copy of the color bar, while the remaining printed color bar (CB-2) is used for the press setup process.

[0033] Color bar nulling at the end of a print run can be done by applying a nulling image onto the printed copies manually and / or by a separate nullifying device, for example, a device including an inkjet printhead that can be implemented as an off-press device.

[0034] Furthermore, color bar nulling can be achieved, for example, by modifying the coordinates that define the position of the color bar on the printed sheet, which can be achieved, for example, by mechanically moving registers on the printing press.

[0035] The present invention is not limited to a single reuse of a printed sheet, but rather the sheet can be reused more than once, for example reused twice so that a third color bar exposure occurs outside the image area, or further reuses so that even more than three color bar exposures occur outside the image area. The number of times a printed sheet is reused is not limited, but in order to maintain an operational press setup process, the ink loading on the printed sheet is preferably not too high. Invalidation of color bars used in a previous print run is preferably performed according to the options detailed above.

[0036] 2 shows an example of a printed sheet (1) obtained after three printing runs according to the method of the present invention. The sheet (1) has printed copies of three images (3) printed in the first, second, and third printing runs, respectively, inside the image area (2), as well as printed copies of three color bars printed in the first, second, and third printing runs, respectively, at positions (Y1), (Y2), and (Y3) along the direction (X) parallel to the axis of the plate cylinder. Two color bars (CB-1') and (CB-2') (the apostrophes indicate nullification) have been nullified by a nullification image (4) on top of the printed copies of the color bars, while the remaining printed color bar (CB-3) is used for the press setup process.

[0037] FIG. 3 shows a scheme of four printing runs according to the invention, which uses the same paper: On the first run, image 1 and one color bar are printed, In the second run, image 2 is printed on top of image 1, a second color bar is printed in a different location than color bar 1, and the first color bar is neutralized by painting a black stroke over its recognition patch; In a third run, image 3 is printed over images 1 and 2, a third color bar is printed in a different location than color bars 1 and 2, and the second color bar is neutralized by painting a black stroke over its recognition patch; In run 4, image 4 is printed over images 1, 2, and 3, a fourth color bar is printed in a different location than color bars 1, 2, and 3, and a third color bar is printed. The bar was neutralized by painting a black stroke over its recognition patch.

[0038] definition The term "aryl," as used herein, preferably refers to phenyl, benzyl, toluyl, ortho-, meta-, or para-xylyl, naphthyl, anthracenyl, fentrenyl, and / or combinations thereof. Heteroaryl groups are preferably monocyclic or polycyclic aromatic rings having carbon atoms and one or more heteroatoms, preferably 1 to 4 heteroatoms, in the ring structure, where the heteroatoms are independently selected from nitrogen, oxygen, selenium, and sulfur. Suitable examples thereof include optionally substituted furyl, pyridinyl, pyrimidyl, pyrazoyl, imidazoyl, oxazoyl, isoxazoyl, thienyl, tetrazoyl, thiazoyl, (1,2,3) triazoyl, (1,2,4) triazoyl, thiadiazoyl, thiophenyl groups, and / or combinations thereof. The optionally substituted heteroaryl is preferably a five- or six-membered ring substituted with one, two, or three oxygen, nitrogen, sulfur, or selenium atoms, or a combination thereof, such as furan, thiophene, pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, oxazole, isoxazole, thiazole, isothiazole, thiadiazole, oxadiazole, pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, or 1,2,3-triazine, benzofuran, benzothiophene, indole, indazole, benzoxazole, quinoline, quinazoline, benzimidazole, or benztriazole.

[0039] The term "alkyl" as used herein refers to all possible variations of alkyl groups of each carbon atom number, i.e., methyl, ethyl, n-propyl and isopropyl for those with 3 carbon atoms, n-butyl, isobutyl and tert-butyl for those with 4 carbon atoms, n-pentyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl and 2-methylbutyl for those with 5 carbon atoms, etc. Preferably, the alkyl group is C1-C 20Preferably, the alkyl group is a C1-C6 alkyl group, more preferably a C1-C6 alkyl group. Most preferably, the alkyl group is a methyl group. Examples of cycloalkyl include substituted or unsubstituted cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, and cyclooctyl groups.

[0040] The term "substituted," when referring to, for example, a substituted alkyl group, means that the alkyl group can be substituted with atoms other than those normally present in such a group (i.e., carbon and hydrogen). For example, a substituted alkyl group can contain a halogen atom or a thiol group. An unsubstituted alkyl group contains only carbon and hydrogen atoms.

[0041] The optional substituents represent alkyl, cycloalkyl, alkenyl or cycloalkenyl groups, alkynyl groups, aryl or heteroaryl groups, alkylaryl or arylalkyl groups, alkoxy groups such as methoxy, ethoxy, iso-propoxy, t-butoxy, (2-hydroxytetradecyl)oxy, and various other straight-chain and branched alkyleneoxyalkoxy groups, aryloxy groups, thioalkyl, thioaryl, or thioheteroaryl groups, hydroxyl groups, -SH, carboxylic acid groups or alkyl esters thereof, sulfonic acid groups or alkyl esters thereof, phosphonic acid groups or alkyl esters thereof, phosphoric acid groups or alkyl esters thereof, amino groups, sulfonamide groups, amide groups, nitro groups, nitrile groups, halogens such as fluoro, chloro, or bromo, or combinations thereof.

[0042] Suitable alkenyl groups herein are preferably C2-C6-alkenyl groups, such as ethenyl, n-propenyl, n-butenyl, n-pentenyl, n-hexenyl, iso- Examples of such groups include isopenyl, iso-butenyl, iso-pentenyl, neo-pentenyl, 1-methylbutenyl, iso-hexenyl, cyclopentenyl, cyclohexenyl, and methylcyclohexenyl groups.

[0043] Suitable alkynyl groups herein are preferably C2-C6-alkynyl groups, suitable aralkyl groups are preferably phenyl or naphthyl groups and have one, two, three or more C1-C6-alkyl groups, suitable aralkyl groups are preferably C1-C6-alkyl groups and have an aryl group, preferably a phenyl or naphthyl group.

[0044] A cyclic group or ring structure, as used herein, contains at least one ring structure and can be a monocyclic or polycyclic group, which means that one or more rings are fused together.

[0045] Printing station: A unit of a printing press used to print one color; a lithographic color station usually contains a plate cylinder carrying the printing master and an inking unit.

[0046] Original printing plate The lithographic printing plate precursor preferably comprises an imageable coating on a hydrophilic support. The imageable coating comprises an image-recording layer that can be positive-acting or negative-acting, i.e., capable of forming ink-receptive areas in exposed or unexposed areas, respectively. The coating can further comprise other layers, such as intermediate layers, adhesion-improving layers, hydrophilizing layers, and / or other layers located between the support and the image-recording layer and / or between the top layer and the image-recording layer.

[0047] Non-limiting examples of suitable supports and suitable heat-sensitive and light-sensitive coatings are discussed in detail below.

[0048] support The support preferably has a hydrophilic surface or is provided with a hydrophilic layer. The support can be a sheet-like material such as a plate, or a cylindrical element such as a sleeve that can be rotated and slid onto the printing cylinder of a printing press. The support is preferably a metal support such as aluminum or stainless steel. The metal can be laminated to a plastic layer, for example, a polyester film. According to another embodiment, the support can be a flexible support provided with a hydrophilic layer, for example, a hydrophilic binder crosslinked with a hardener such as formaldehyde, glyoxal, polyisocyanate, or hydrolyzed tetraalkyl orthosilicate. The flexible support can be, for example, paper, plastic film, thin aluminum, or a laminate thereof. Suitable examples of plastic films include polyethylene terephthalate film, polyethylene naphthalate film, cellulose acetate film, polystyrene film, polycarbonate film, etc. The plastic film support can be opaque or transparent.

[0049] Most preferred are milled and anodized aluminum supports, which are well known in the art. Suitable supports are disclosed, for example, in EP1843203 (paragraphs

[0066] to

[0756] ). The surface roughness obtained after the milling step, expressed as the arithmetic mean centerline roughness Ra (ISO 4287 / 1 or DIN 4762), can vary between 0.05 and 1.5 μm, more preferably between 0.3 and 0.6 μm. Anodizing the aluminum support forms an Al2O3 layer, the weight of which (g / m 2 Al2O3) is 1 to 8 g / m 2 , more preferably 2 to 3 g / m 2 It is possible to vary between

[0050] The milled and anodized aluminum support can be subjected to a so-called post-anodic treatment and / or pore-widening treatment. Suitable examples of anodic post-treatments include treatment with poly(vinylphosphonic acid) or its derivatives, treatment with poly(acrylic acid), treatment with potassium fluorozirconate or phosphate, treatment with alkali metal silicate, or a combination thereof. Alternatively, the support can be treated with an adhesion-promoting compound such as those described in EP1788434

[0010] and WO 2013 / 182328.

[0051] Heat-sensitive printing plate The imaging mechanism of the heat-sensitive printing plate can be triggered by direct exposure to heat, for example, by a thermal head, or by light absorption of one or more compounds in the coating that can convert light, preferably infrared light, into heat.Suitable examples of such compounds include pigments such as carbon black, and / or more preferably IR dyes that can be added to the image-recording layer and / or optional other layers.Such heat-sensitive lithographic printing plate is preferably insensitive to visible light, i.e., exposure to visible light does not induce a substantial effect on the dissolution rate of the coating in the developer.Most preferably, the coating is insensitive to ambient sunlight.

[0052] Hydrophobic thermoplastic polymer particles A first suitable example of a heat-sensitive printing plate master is a master based on the heat-induced coalescence of hydrophobic thermoplastic polymer particles, which are preferably dispersed in a hydrophilic binder, as described, for example, in EP 770 494, EP 770 495, EP 770 497, EP 773 112, EP 774 364, EP 849 090, EP 1 614 538, EP 1 614 539, EP 1 614 540, EP 1 777 067, EP 1 767 349, WO 2006 / 037716, WO 2006 / 133741, and WO 2007 / 045515.

[0053] Specific examples of suitable hydrophobic thermoplastic polymers include polyethylene, poly(vinyl chloride), poly(methyl (meth)acrylate), poly(ethyl (meth)acrylate), poly(vinylidene chloride), poly(meth)acrylonitrile, poly(vinylcarbazole), polystyrene, or copolymers thereof. Polystyrene and poly(meth)acrylonitrile, or derivatives thereof, preferably containing at least 50% by weight of polystyrene, more preferably at least 60% by weight of polystyrene, are particularly preferred embodiments. To achieve sufficient resistance to organic chemicals, such as hydrocarbons, used in plate cleaners, the thermoplastic polymer preferably contains at least 5% by weight, more preferably at least 30% by weight, of nitrogen-containing monomer units or units corresponding to monomers characterized by a solubility parameter greater than 20, such as (meth)acrylonitrile. According to a most preferred embodiment, the thermoplastic polymer is a copolymer of styrene and acrylonitrile units in a weight ratio of 1:1 to 5:1 (styrene:acrylonitrile), for example, a 2:1 ratio.

[0054] Preferably, the image-recording layer comprises an organic compound containing at least one phosphonic acid group or at least one phosphoric acid group or salts thereof, as described in WO 2007 / 04551.

[0055] The weight average molecular weight of the thermoplastic polymer particles can be in the range of 5,000 to 1,000,000 g / mol. The hydrophobic particles preferably have a number average particle size of less than 200 nm, more preferably 10 to 100 nm. The amount of hydrophobic thermoplastic polymer particles contained in the image recording layer is preferably 20 to 65% by weight, more preferably 25 to 55% by weight. The most preferred range is 30% to 45% by weight.

[0056] The thermoplastic polymer particles are preferably dispersed in a hydrophilic binder, which may be selected from homopolymers and copolymers of, for example, vinyl alcohol, acrylamide, methylol acrylamide, methylol methacrylamide, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, or maleic anhydride / vinyl methyl ether copolymers. The hydrophilicity of the (co)polymer or (co)polymer mixture used is preferably the same as or higher than that of polyvinyl acetate hydrolyzed to a degree of at least 60% by weight, preferably 80% by weight.

[0057] After image-wise exposure, the image-recording layer of this embodiment can be developed off-press with an aqueous developer. Such embodiments preferably include a contrast dye or pigment that provides a visible image after development, and this dye or pigment can be added to any layer of the imageable coating.

[0058] Suitable developers are gum solutions which allow image development and gumming to occur simultaneously in a single step as described in EP1342568 or in a cascade arrangement as described, for example, in WO2007 / 057349.

[0059] The image-recording layer of this embodiment can also be developed on press using dampening fluid and / or ink, i.e., the non-printing areas of the image can be removed by dampening fluid and / or ink supplied to the plate by a lithographic press. Such embodiments preferably contain a leuco dye or thermochromic IR dye that produces an immediately visible image upon exposure (i.e., before processing) so that the image can be confirmed before the plate is mounted on the plate cylinder of the press. Such a leuco dye or thermochromic IR dye can be added to any layer of the imageable coating. Suitable thermochromic IR dyes are described in EP 1736312. After mounting on the press, the plate is processed by rotating the plate cylinder while supplying dampening fluid and / or ink to the exposed master. In a preferred embodiment, only dampening fluid is supplied to the plate for the first 60 seconds, more preferably the first 30 seconds, and most preferably the first 15 seconds after press start-up, and then the ink supply is also switched on. In alternative embodiments, the dampening fluid and ink supply can be started simultaneously, or only ink can be supplied for multiple revolutions before the dampening fluid supply is switched on. Preferred embodiments of the imageable coating require fewer than 25 printed copies to completely remove the non-printed areas of the image from the substrate.

[0060] Aryl diazosulfonate homopolymer or copolymer In a second suitable embodiment, the heat-sensitive printing plate master has a coating comprising an aryl diazosulfonate homopolymer or copolymer, which is hydrophilic and processing solution soluble before exposure to heat or UV light, and which becomes hydrophobic and less soluble after exposure thereto.

[0061] Suitable examples of such aryldiazosulfonate polymers are compounds that can be prepared by homopolymerization or copolymerization of an aryldiazosulfonate monomer with another aryldiazosulfonate monomer and / or a vinyl monomer, such as (meth)acrylic acid or its ester, (meth)acrylamide, acrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, styrene, α-methylstyrene, etc. Suitable aryldiazosulfonate monomers are described in EP 339393, EP 507008, and EP 771645, and suitable aryldiazosulfonate polymers are described in EP 507,008, EP 960,729, EP 960,730, and EP 1,267,211. Positive heat-sensitive printing plate Further suitable heat-sensitive printing plates are positive-working and rely on heat-induced solubilization of a hydrophobic and / or oleophilic resin. The resin is preferably a polymer that is soluble in an aqueous developer, more preferably an aqueous alkaline developer having a pH of 7.5 to 14. Suitable polymers are phenolic resins, such as novolaks, resoles, polyvinylphenols, and carboxy-substituted polymers. Typical examples of these polymers are described in EP 823327 and WO 1997 / 039894. The amount of phenolic resin present in the imaging layer is preferably at least 50% by weight, preferably at least 80% by weight, based on the total weight of all components present in the imaging layer.

[0062] In a preferred embodiment, the hydrophobic or oleophilic resin is a phenolic resin, in which phenyl or hydroxy groups are chemically modified with organic substituents. The phenolic resin chemically modified with organic substituents can exhibit improved chemical resistance to printing chemicals, such as plate processing solutions such as dampening solutions or plate cleaners. Examples of such chemically modified phenolic resins are described in EP 934 822, EP 1 072 432, US 5 641 608, EP 0 982 123, WO 99 / 01795, EP 02 102 446, EP 02 102 444, EP 02 102 445, EP 02 102 443, EP 03 102 522. Preferred are modified resins as described in EP 02 102 446, particularly preferred are resins in which the phenyl groups of the phenolic resins are substituted with groups having the structure -N=NQ, where the -N=N- group is covalently bonded to a carbon atom of the phenyl group and Q is an aromatic group.

[0063] The phenolic resin can also be mixed with or replaced by other polymers, such as poly(vinyl acetal) resins, to improve the abrasion resistance of the coating. Suitable poly(vinyl acetal) resins are copolymers having acetal and ethylene moieties, as described in WO 2014 / 106554, WO 2015 / 158566, WO 2015 / 173231, WO 2015 / 189092, and WO 2016 / 001023. Particularly suitable poly(vinyl acetal) resins are those having ethylene and acetal moieties and containing an optionally substituted aromatic or heteroaromatic group having at least one hydroxyl group (WO 2014 / 106554), or poly(vinyl acetal) resins containing an optionally substituted aromatic or heteroaromatic group are those having at least one hydroxyl group in the ortho or para position relative to an electron-withdrawing group (WO 2015 / 158566).

[0064] The coating can further comprise a second layer containing one or more other binders, which are water-insoluble and alkaline-soluble, such as organic polymers with acidic groups having a pKa of less than 13, to ensure that the second layer is soluble in, or at least swellable in, an aqueous alkaline developer. This layer is located between the layer containing the hydrophobic or oleophilic resin and the hydrophilic support. The binder can be selected from polyester resins, polyamide resins, epoxy resins, polyimides, acrylic resins, methacrylic resins, styrene-based resins, polyurethane resins, or polyurea resins. The binder can have one or more functional groups. (Co)polymers containing sulfonamide groups are preferred. Sulfonamide (co)polymers are preferably high-molecular-weight compounds prepared by homopolymerization of a monomer having at least one sulfonamide group or by copolymerization of such a monomer with other polymerizable monomers. Examples of monomers copolymerizable with the monomer having at least one sulfonamide group are described in EP 1 262 318 and EP 1 262 318. EP 1 275 498, EP 909 657, EP 1 120 246, EP 894 622, US 5,141,838, EP 1 545 878, and EP 1 400 351.

[0065] Suitable examples of sulfonamide (co)polymers and / or methods for their preparation are described in EP 933 682, EP 982 123, EP 1 072 432, WO 99 / 63407, EP 1 400 351, and EP 2 159 049. Highly suitable examples of sulfonamide (co)polymers are described in EP 2 047 988 A,

[0044] to

[0046] .

[0066] Suitable specific examples of sulfonamide (co)polymers are polymers containing N-(p-aminosulfonylphenyl)(meth)acrylamide, N-(m-aminosulfonylphenyl)(meth)acrylamide, N-(o-aminosulfonylphenyl)(meth)acrylamide, and / or m-aminosulfonylphenyl (meth)acrylate.

[0067] The dissolution behavior of the coating can be fine-tuned by optional solubility-controlling components. More particularly, developability-enhancing compounds, development accelerators, and development inhibitors can be used. In embodiments where the coating comprises multiple layers, such components can be added to the first layer, and / or the second layer, and / or to any other layer of the coating.

[0068] Suitable developability-improving compounds include (i) compounds that release gases when heated, as disclosed in WO 2003 / 79113, (ii) compounds as disclosed in WO 2004 / 81662, (iii) compositions containing one or more basic nitrogen-containing organic compounds, as disclosed in WO 2008 / 103258, and (iv) organic compounds having at least one amino group and at least one carboxylic acid group, as disclosed in WO 2009 / 85093. Further details about developability-improving compounds are described in WO 2017 / 157575

[0066] to

[0077] .

[0069] Suitable dissolution inhibitors are preferably organic compounds that have at least one aromatic group and hydrogen bonding sites that interact with hydrophobic or lipophilic alkali-soluble polymers, for example, with the hydroxyl group of phenolic resins.Suitable examples of hydrogen bonding sites include carbonyl groups, sulfonyl groups, or nitrogen atoms that can be quaternized and can be part of heterocyclic rings or can be part of the amino substituents of the organic compounds.Suitable dissolution inhibitors of this type are, for example, disclosed in EP823327A and WO1997 / 039894.

[0070] The coating of the heat-sensitive printing plate precursor described above preferably also contains an infrared light-absorbing dye or pigment, which can be present in the first layer, and / or the second layer, and / or any other layer in embodiments in which the coating has multiple layers. Suitable IR dyes have an absorption peak between 750 nm and 1300 nm, more preferably between 780 nm and 1100 nm, and most preferably between 800 nm and 850 nm. Suitable classes of IR dyes are cyanine dyes, merocyanine dyes, indoaniline dyes, oxonol dyes, pyrylium dyes, and squarylium dyes. Examples of suitable IR dyes are, for example, EP 823327, EP978376, EP1029667, EP1053868, EP1093934, EP1359008, WO 1997 / 39894, and 2000 / 29214.

[0071] The concentration of the IR dye in the coating is preferably 0.25 to 15.0% by weight, more preferably 0.5 to 10.0% by weight, and most preferably 1.0 to 7.5% by weight, based on the total weight of the coating.

[0072] The coating may further comprise one or more colorants, such as dyes or pigments, which impart visible color to the coating and which remain in the coating in the image areas that are not removed during processing. The ink may contain one or more dyes, often referred to as contrast or indicator dyes, which produce a visible image and allow inspection of the lithographic image on the developed printing plate.

[0073] A protective layer can also be applied to the surface of the coating of the heat-sensitive and / or photosensitive printing plate precursor to protect it, especially from mechanical damage. The protective layer generally contains at least one water-soluble binder, such as polyvinyl alcohol, polyvinylpyrrolidone, partially hydrolyzed polyvinyl acetate, gelatin, carbohydrates, or hydroxyethyl cellulose, and can be prepared in any known manner, for example, from an aqueous solution or dispersion, which, if necessary, can contain only a small amount of organic solvent, i.e., less than 5% by weight based on the total weight of the coating solvent for the protective layer. The thickness of the protective layer can be any suitable amount, advantageously up to 5.0 μm, preferably 0.1 to 3.0 μm, and particularly preferably 0.15 to 1.0 μm.

[0074] Optionally, the coating may further contain additional components such as surfactants, especially silicon or perfluorosurfactants, silicon dioxide or titanium dioxide particles, or polymer particles such as matting agents and spacers.

[0075] Any coating method can be used to apply one or more coating solutions to the hydrophilic surface of the support. Multilayer coatings can be applied by sequentially coating and drying each layer, or by simultaneously coating multiple coating solutions at once. In the drying process, volatile solvents are removed from the coating until the coating is self-supporting, dry, and tough. However, it is not necessary (or even likely possible) for all solvent to be removed in the drying process. In fact, the residual solvent content can be considered an additional component, by which means the composition can be optimized. Drying is typically performed by blowing hot air onto the coating, typically at a temperature of at least 70°C, suitably 80 to 150°C, and especially 90 to 140°C. Infrared lamps can also be used. Drying times can typically be 15 to 600 seconds.

[0076] Heat treatment and subsequent cooling between coating and drying, or after the drying step, can provide additional benefits, as described in WO 99 / 21715, EP 1074386, EP 1074889, WO 00 / 29214, and WO / 04030923, WO / 04030924, WO / 04030925.

[0077] The printing master can be exposed to infrared light by means of, for example, an LED or a laser. Most preferably, the light used for exposure is a laser emitting near-infrared light having a wavelength in the range of about 750 to about 1500 nm, more preferably 750 to 1100 nm, such as a semiconductor laser diode, Nd:YAG, or Nd:YLF laser. The required laser power depends on the sensitivity of the master, the spot diameter (typical values ​​for modern master settings are a maximum intensity of 1 / e 2 It depends on the pixel dwell time of the laser beam, defined by the scanning speed (i.e., 5-25 μm), the scanning speed, and the resolution of the exposure device (i.e., the number of addressable pixels per unit of linear distance, often expressed in dots per inch or dpi; typical values: 1000-4000 dpi).

[0078] After imagewise exposure, the coating can be developed off-press with an aqueous alkaline developer. Suitable developer compositions are disclosed in WO2017 / 157570 and suitable processing equipment is disclosed in WO2017 / 157571.

[0079] Photosensitive printing plate In addition to the above heat-sensitive printing plate precursor, a photopolymerizable and / or photocrosslinkable composition that hardens upon exposure to light is also included. Also of interest are photosensitive printing plate masters containing such materials, such as UV-sensitive "PS" printing plates and photopolymer printing plates.

[0080] Suitable examples of UV-sensitive "PS" printing plates are those sensitive in the range of 300 to 450 nm (near UV and blue light) and are discussed in EP 1 029 668. Positive compositions utilizing o-naphthoquinone diazides and negative compositions utilizing diazonium salts, diazonium resins, or aryl diazosulfonate homopolymers or copolymers are typically used in "PS" printing plates.

[0081] A photosensitive printing plate precursor utilizing photopolymerization and / or crosslinking reaction has a coating including a layer containing a photopolymerizable and / or photocrosslinkable composition, which layer is also referred to as a "photopolymerizable layer." The coating may further include an intermediate layer, which is located between the support and the photopolymerizable layer, the surface layer, and / or any other optional layers. The photopolymerizable layer preferably has a coating thickness of 0.2 to 5.0 g / m 2 , more preferably 0.4 to 3.0 g / m 2 , and most preferably 0.6 to 2.2 g / m 2 is in the range.

[0082] The photopolymerizable coating is preferably sensitive to (ultraviolet) violet, visible, or IR light. While the peak sensitivity of (ultraviolet) violet compositions can be greater than 420 nm, better light stability can be achieved with compositions whose peak sensitivity is at shorter wavelengths, preferably less than 420 nm, more preferably less than 410 nm. The availability of laser diodes emitting in the near-UV wavelength range, e.g., 365 or 375 nm, makes compositions with peak sensitivity outside the visible wavelength range, i.e., less than 400 nm, particularly advantageous. According to another embodiment, the peak sensitivity of the photopolymerizable coating is in the IR wavelength range, preferably near-IR light with wavelengths between 750 and 1100 nm, more preferably between 780 and 850 nm.

[0083] Suitable photopolymerizable or photocrosslinkable compositions comprise a polymerizable or crosslinkable compound, an initiator, a (ultraviolet) violet and / or infrared sensitizer, and a polymeric binder.

[0084] The polymerizable or crosslinkable compound is preferably a monomer or oligomer having at least one terminal ethylene group, hereinafter also referred to as a "free radical polymerizable monomer." The polymerization initiator is a compound capable of generating free radicals upon exposure (hereinafter also referred to as a "free radical initiator"), optionally in the presence of a photosensitizer.

[0085] Suitable free-radically polymerizable monomers or oligomers include, for example, polyfunctional (meth)acrylate monomers, such as (meth)acrylate esters of ethylene glycol, trimethylolpropane, pentaerythritol, ethoxylated ethylene glycol, and ethoxylated trimethylolpropane, polyfunctional urethane-modified (meth)acrylates, and epoxidized (meth)acrylates, and oligomeric amine diacrylates. The (meth)acrylic monomers may also have another double bond or epoxide group in addition to the (meth)acrylate group. The (meth)acrylate monomers may also have acidic (e.g., carboxylic acid) or basic (e.g., amine) groups. Suitable free-radically polymerizable monomers are disclosed in EP2916171, paragraphs

[0042] and

[0050] .

[0086] Suitable free radical initiators are described, for example, in WO 2005 / 111727, page 15, line 17 to page 16, line 11, EP 1091247A, and EP 3594009A. Suitable free radical initiators include, for example, hexaaryl-bisimidazole compounds (HABI; dimers of triaryl-imidazole), aromatic ketones, organic peracids, etc. Examples of compounds include oxidized compounds, thio compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, and compounds having a carbon-halogen bond.

[0087] Suitable free radical initiators are optionally substituted trihaloalkylsulfone compounds (hereinafter referred to as "THS" compounds), in which halo independently represents bromo, chloro, or iodo, and sulfone is a compound having a sulfonyl group (-SO-) bonded to two carbon atoms. More preferably, the THS compound is an optionally substituted trihaloalkyl(hetero)arylsulfone, i.e., a compound in which a sulfonyl group is bonded to an optionally substituted trihaloalkyl group and to an optionally substituted aryl or optionally substituted heteroaryl group. The aryl group is preferably optionally substituted phenyl, benzyl, toluyl, or ortho-, meta-, or para-xylyl, naphthyl, anthracenyl, fentrenyl, and / or combinations thereof. The heteroaryl group is preferably an optionally substituted monocyclic or polycyclic aromatic ring having carbon atoms and one or more heteroatoms, preferably 1 to 4 heteroatoms, in the ring structure, independently selected from nitrogen, oxygen, selenium, and sulfur. Suitable examples thereof include furan, thiophene, pyrrole, pyrazole, imidazole, 1,2,3- or 1,2,4-triazole, tetrazole, oxazole, isoxazole, thiazole, isothiazole, thiadiazole, oxadiazole, pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-, 1,2,4-, or 1,2,3-triazine, benzofuran, benzothiophene, indole, indazole, benzoxazole, quinoline, quinazoline, benzimidazole, or benzotriazole. The most suitable THS compound is optionally substituted tribromomethyl aryl sulfone, most preferably optionally substituted tribromomethyl phenyl sulfone.

[0088] The amount of THS initiator typically ranges from 0.1 to 30 wt %, preferably from 0.5 to 10 wt %, and most preferably from 2 to 7 wt %, based on the total dry weight of the nonvolatile components of the photopolymerizable or photocrosslinkable composition.

[0089] Another group of suitable free radical initiators are onium salts, particularly iodonium salts and sulfonium salts, or mixtures thereof. A suitable class of iodonium salts is the optionally substituted diaryliodonium salts or diheteroaryliodonium salts. Specific examples of diaryliodonium salts include diphenyliodonium, 4-methoxyphenyl-4-(2-methylpropyl)phenyliodonium, 4-chlorophenyl-4-phenyliodonium, 4-(2-methylpropyl)phenyl-toluyliodonium, 4-hexyloxyphenyl-2,4,6-trimethoxyphenyliodonium, 4-hexyloxyphenyl-2,4-diethoxyphenyliodonium, 4-octyloxyphenyl-6-trimethoxyphenyliodonium, bis(4-tert-butylphenyl)iodonium, and bis(4-isopropylphenyl)iodonium, 4-octyloxyphenylphenyliodonium, [4-[(2-hydroxytetradecyl)oxy]phenyliodonium], and the like. [nyl]phenyliodonium, 4-methylphenyl-4'-hexylphenyliodonium tetraphenylborate, 4-methylphenyl-4'-cyclohexylphenyliodonium, 4-hexylphenyl-phenyliodonium, 4-methylphenyl-4'cyclohexylphenyliodonium, 4-cyclohexylphenyl-phenyliodonium, 2-methyl-4-t-butylphenyl-4'-methylphenyliodonium, (4-tert-butylphenyl)-(4-methoxyphenyl)iodonium, phenyl(4-tert-butylphenyl)iodonium, phenyl(4-cumylphenyl)iodonium, phenyl(3-cumylphenyl)iodonium, and / or mixtures thereof.

[0090] Suitable examples of the triarylsulfonium salt include triphenylsulfonium, dialkylphenacylsulfonium, dialkyl-4-hydroxyphenylsulfonium, bis(4-chlorophenyl)phenylsulfonium, triphenylsulfonium benzoyl formate, bis(4-chlorophenyl)phenylsulfonium benzoyl formate, bis(4-chlorophenyl)-4-methylphenylsulfonium, bis(4-chlorophenyl)-4-methylphenylsulfonium, tris(4-chlorophenyl)sulfonium, tris(2,4-dichlorophenyl)sulfonium, bis(2,4-dichlorophenyl)phenylsulfonium, and bis(2,4-dichlorophenyl)4-methoxyphenylsulfonium.

[0091] Suitable counterions for onium salts are, for example, PF6 - , SbF6 - , AsF6 - and organoboron anions, more preferably optionally substituted tetraphenylborate anions. The onium salt is preferably present in the image-recording layer in an amount of 1 to 25% by weight, more preferably 5 to 20% by weight, and most preferably 10 to 16% by weight.

[0092] The photopolymerizable or photocrosslinkable layer can also include a coinitiator used in combination with the free radical initiator. Suitable coinitiators are disclosed in US Pat. No. 6,410,205, US Pat. No. 5,049,479, EP 1,079,276, EP 1,077,92, EP 1,369,232, EP 1,369,231, EP 1,341,040, US 2003 / 0124,460, EP 1,241,002, EP 1,288,720, and references cited therein, including Chemistry & Technology: UV & EB formulation for coatings, inks & paints - Volume 3 - Photoinitiators for Free Radical and Cationic Polymerization by KK Dietliker - Edited by PKT Oldring (1991; ISBN 0947798161). Suitable coinitiators are disclosed in EP 2,916,171A (paragraph

[0051] ). A highly suitable coinitiator is tetraphenylborate, which can be added as a salt, for example sodium or potassium tetraphenylborate, or as a counterion to another component, such as the onium initiators listed above.

[0093] Suitable (ultraviolet) violet sensitizers are dyes having an absorption peak in the wavelength range of 320 nm to 500 nm, preferably 350 to 450 nm, and more preferably 360 to 420 nm. Suitable (near) infrared sensitizers are dyes having an absorption peak in the wavelength range of 750 to 1100 nm, preferably 780 to 850 nm, and more preferably 810 to 830 nm. The best light stability is obtained by using sensitizers having an absorption peak below 400 nm and / or above 750 nm. The absorption peak wavelengths mentioned are values ​​as measured in the dry matrix of the imageable coating of the master.

[0094] Suitable (ultraviolet) violet sensitizers are disclosed, for example, in EP 1349006. Preferred classes of (ultraviolet) violet sensitizers are fluorenes, thioxanthenes, (keto)coumarins, pyrylium dyes, or thiopyrylium dyes. More preferred dyes have the general structure Sty-Ar-Sty, where each "Sty" group is an optionally substituted styryl (CH-CH=CH-) group, and Ar is an optionally substituted aromatic or optionally substituted heteroaromatic group that forms a conjugated system with the Sty groups. The two Sty groups can be the same or different. Examples of Ar include, preferably, benzene, naphthalene, anthracene, fluorene, biphenyl, carbazole, furan, dibenzofuran, thiophene, dibenzothiophene, dithienothiophene, oxadiazole, thiadiazole, pyridine, pyrimidine, and combinations of two or more of these groups, which groups can be the same or different. Dyes in which the alkyl group is phenyl or phenyl are most preferred. Suitable examples of such distyrylbiphenyl and distyrylbenzene compounds are disclosed in WO2005 / 029187 and WO2008 / 145528.

[0095] Suitable near-IR sensitizers include IR light-absorbing dyes and pigments. A suitable pigment is carbon black. Suitable IR dyes have an absorption peak at 750 nm to 1300 nm, more preferably 780 nm to 1100 nm, and most preferably 800 nm to 850 nm. Suitable IR dyes include merocyanines, indoanilines, oxonols, pyrium dyes, squarylium dyes, and cyanine dyes, particularly heptamethine cyanine dyes. Examples of suitable IR dyes are described in, for example, EP823327, EP978376, EP1029667, EP1053868, EP1093934, EP1359008, WO97 / 39894, and WO00 / 29214. Highly suitable IR dyes, such as those disclosed in EP 1736312, EP 1910082, and WO 2019 / 219560, produce an immediately visible image upon imagewise exposure. Such thermochromic IR dyes can also be used in the overcoat.

[0096] Mixtures of sensitizers can also be used, such as mixtures of two or more of the above dyes, or mixtures of the above dyes with other sensitizers. The total concentration of the sensitizer(s) relative to the total dry weight of the image-recording layer is preferably 0.25 to 25.0 wt %, more preferably 0.5 to 20.0 wt %, and most preferably 1.0 to 10.0 wt %.

[0097] The binder can be selected from a wide range of organic polymers. Mixtures of different binders can also be used. Useful binders are described in WO 2005 / 111727, page 17, line 21 to page 19, line 30; EP 1043627, paragraph

[0013] ; and WO 2005 / 029187, page 16, line 26 to page 18, line 11. Specific examples of binders are described in US Pat. No. 6,899,994, US 2004 / 0260050, US 2005 / 0003285, US 2005 / 0170286, US 2005 / 0123853, and EP 2916171, paragraphs

[0029] ,

[0030] , and

[0031] . Other suitable binders, as described in EP2471655, EP2492748, and EP2660068, include those in which a polymer chain is linked to a polyfunctional thiol having 6 to 10 functional groups as a core (central skeleton) through a sulfide bond. The image-recording layer may also optionally contain one or more co-binders. Typical co-binders are water-soluble or water-dispersible polymers, such as cellulose derivatives, polyvinyl alcohol, polyacrylic acid, poly(meth)acrylic acid, polyvinylpyrrolidone, polylactide, polyvinylphosphonic acid, synthetic copolymers, such as alkoxypolyethylene glycol (meth)acrylate copolymers, and the like. Specific examples of co-binders are described in US 2004 / 0260050, US 2005 / 0003285, and US 2005 / 0123853.

[0098] The photopolymerizable or photocrosslinkable coating can contain discrete particles, i.e., particulate polymers, including homopolymers or copolymers prepared from monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile, vinyl carbazole, acrylates, or methacrylates, or mixtures thereof. Preferably, the discrete particles are particles suspended in the photopolymerizable composition. The presence of discrete particles tends to facilitate the developability of non-image areas.

[0099] The photopolymerizable or photocrosslinkable coating can include thermally reactive polymeric microparticles having thermally reactive groups, such as ethylenically unsaturated groups, cationically polymerizable groups, isocyanate groups, epoxy groups, vinyloxy groups, and active hydrogen atoms, carboxy groups, hydroxyl groups, and the like. The polymer particles preferably have a functional group having a hydroxyl group, an amino group, or an acid anhydride. The average particle size of the polymer particles is preferably 0.01 μm to 3.0 μm. Particulate polymers in the form of microcapsules, microgels, or reactive microgels are suitable, as disclosed in EP1132200, EP1724112, and US2004 / 106060.

[0100] The photopolymerizable or photocrosslinkable coating can also contain particles that improve the coating's resistance to manual or mechanical damage, such as inorganic particles, organic particles, or fillers, such as those described in U.S. Pat. No. 7,108,956. Spacer particles can also be added to the coating. Further details of suitable spacer particles are described in EP 2 916 171, paragraphs

[0053] to

[0056] . The spacer particles can be substituted with one or more reactive groups.

[0101] Photopolymerizable or photocrosslinkable coatings are described, for example, in US Pat. No. 6,410,205, EP 1 288 720, and EP 1 749 240.

[0102] The photopolymerizable or photocrosslinkable coating may further comprise an adhesion-promoting compound. The adhesion-promoting compound is a compound capable of interacting with the substrate, preferably a compound having an addition-polymerizable ethylenically unsaturated bond and a functional group capable of interacting with the substrate. "Interact" is understood to mean any physical and / or chemical reaction or process in which a bond is formed between the functional group and the substrate. This bond can be a covalent bond, an ionic bond, a complex bond, a coordinate bond, or a hydrogen bond, and this bond can be formed by an adsorption process, a chemical reaction, an acid-base reaction, a complexation reaction, or a reaction of a chelating group or a ligand. The adhesion-promoting compounds described in paragraph

[0058] of EP 2 916 171 are suitable compounds.

[0103] Various surfactants can be added to the photopolymerizable or photocrosslinkable coating to allow or improve the developability of the master, especially to allow or improve development using a gum solution. Both polymeric surfactants and small molecule surfactants, such as nonionic surfactants, are suitable. Further details are described in paragraph

[0059] of EP 2 916 171.

[0104] The above-described components present in the photopolymerizable coating can be present in the photopolymerizable layer, the optional intermediate layer, the optional top layer, and / or any other optional layer.

[0105] The optional surface layer, overcoat, or protective overcoat layer preferably acts as an oxygen barrier layer containing a water-soluble or water-swellable binder. A printing plate blank without a surface layer or protective overcoat layer is also referred to as an overcoat-free printing plate blank. The surface layer preferably improves the sensitivity of the printing plate by reducing quenching by oxygen of free radicals generated in the image-recording layer upon imagewise exposure.

[0106] The surface layer is preferably easily removable during development, adheres well to the photopolymerizable layer or optional other layers of the coating, and preferably does not inhibit light transmission during exposure. The overcoat is preferably easily removable during development, and preferably adheres well to the photopolymerizable layer or optional other layers of the coating. The overcoat is preferably soluble or dispersible in water or ink so that the overcoat is easily removable by an aqueous developer or by a fountain solution during development. Consequently, the overcoat preferably comprises a hydrophilic binder. Suitable binders that can be used in the surface layer are disclosed in WO2005 / 029190 (page 36, line 3 to page 39, line 25), US2007 / 0020563 (paragraph

[0158] ), and EP1288720A (paragraphs

[0148] and

[0149] ). This patent application also includes references cited in these patent applications.

[0107] The most suitable binder for the surface layer is polyvinyl alcohol. The polyvinyl alcohol preferably has a degree of hydrolysis in the range of 74 mol% to 99 mol%, more preferably 88 to 98%. The weight-average molecular weight of polyvinyl alcohol can be measured by the viscosity of a 4 wt% aqueous solution at 20°C as specified in DIN 53 015, and this viscosity number is preferably in the range of 2 to 26, more preferably 2 to 15, and most preferably 2 to 10.

[0108] Mixtures of hydrophilic binders can also be used, such as mixtures of two or more water-soluble polymers, such as a combination of poly(vinyl alcohol) and poly(vinylpyrrolidone), or mixtures of poly(vinyl alcohol) and / or poly(vinyl alcohol) derivatives having different hydrolysis and viscosity numbers. Modified poly(vinyl alcohol), such as poly(vinyl alcohol) with carboxyl and / or sulfonic acid groups, can also be used, preferably together with unmodified poly(vinyl alcohol).

[0109] The surface layer can comprise a halogenated polymer, which is preferably a hydrophobic polymer, i.e., one that does not dissolve or swell in water at about neutral pH. The binder, as disclosed in EP 3587112 and EP 3587113, can be used in the form of a dispersion, i.e., an emulsion or suspension. The amount of halogenated polymer can be 30% to 96% by weight, more preferably 40% to 90% by weight, and most preferably 50% to 85% by weight, based on the total dry weight of the overcoat. The halogenated binder preferably comprises 60% to 95% by weight of monomer units derived from vinylidene monomers, such as vinylidene fluoride, vinylidene chloride, vinylidene bromide, and / or vinylidene iodide.

[0110] The surface layer may contain other components, such as anionic surfactants such as sodium alkyl sulfate or sodium alkyl sulfonate, dioctyl sodium sulfosuccinate, sodium dodecylbenzenesulfonate, and ammonium lauryl sulfate; amphoteric surfactants such as alkylaminocarboxylates and alkylamino-dicarboxylates; nonionic surfactants such as polyethylene glycol, polypropylene glycol, and copolymers of ethylene glycol and propylene glycol, polysiloxane surfactants, perfluorocarbon surfactants, alkylphenylethylene oxide condensates, and alkoxylated alkylenediamines disclosed in EP1085380 (paragraphs

[0021] and

[0022] ); and various additives such as glycerin, pigments, matting agents or wetting agents as disclosed in EP2916171, (inorganic) organic acids such as the acids disclosed in EP2149071, page 27, lines 1 to 21, colorants, and / or printing out agents. Microparticles can also be added to the overcoat, for example to reduce the tackiness or water sensitivity of the plate.

[0111] In a highly preferred embodiment of the master for use in the present invention, the surface layer further comprises a thermochromic dye that produces a visible image upon image-wise exposure with IR light, as disclosed in WO2019 / 219560.

[0112] The coating thickness of the surface layer is preferably 0.10 to 1.75 g / m 2 , more preferably 0.20 to 1.3 g / m 2 , and most preferably 0.25 to 1.0 g / m 2 In a more preferred embodiment of the present invention, the optional surface layer has a coating thickness of 0.25 to 1.75 g / m 2 and the polyvinyl alcohol has a degree of hydrolysis in the range of 74 mol % to 99 mol % and a viscosity number in the range of 3 to 26 as defined above.

[0113] The master can be imagewise exposed to UV, violet, or IR light, preferably by a laser. UV and violet light are preferably radiant energy having wavelengths in the range of 350 to 450 nm, more preferably 360 to 420 nm, and most preferably 400 to 410 nm. Suitable UV and violet lasers are laser diodes, particularly gallium nitride diodes, emitting at 375 nm or 405 nm, respectively. Frequency-doubled gallium arsenide diodes emitting at 410 nm can also be used. IR light is preferably near-IR electromagnetic radiation having a wavelength in the range of 750 to 1100 nm, more preferably 780 to 850 nm. Suitable IR lasers are laser diodes emitting at approximately 830 nm or Nd:YAG lasers emitting at 1064 nm.

[0114] The sensitivity of a master is defined as the energy density of the laser beam measured at the surface of the plate coating required to produce a lithographic image, and is generally between 0.01 and 250 mJ / cm 2 , and more preferably 0.1 to 10 mJ / cm for plates sensitive to (ultraviolet) violet light. 2 and for plates sensitive to infrared light, it is 50 to 200 mJ / cm 2The optimum value for type C plates depends not only on the wavelength but also on the nature and thickness of the overcoat; plates with thinner overcoats require more energy than plates with thicker overcoats because they offer less protection against oxygen quenching.

[0115] After imagewise exposure, the image-recording layer can be developed off-press or on-press using the same developer, method, and processor as described above. The optional surface layer is preferably removed together with the non-image areas of the recording layer in a single process. Alternatively, a pre-washing step can be performed to remove the surface layer before the image-recording layer is developed. The pre-washing step can be performed in a separate device, by manually rinsing the master with water, or in a wash unit built into the processor used to develop the image-recording layer. The wash liquid is preferably water, more preferably tap water. [Example]

[0116] The printing masters used were commercially available Eclipse plates from Agfa Offset BV, Belgium. Eclipse is a "DOP" material containing an infrared-sensitized photopolymerizable composition. For each printing run, four printing plates measuring 1055 mm x 811 mm were prepared and directed to the CMYK printing station of the press described below. The plates were fired at an energy density of 130 mJ / cm using 200 lpi Agfa Balanced Screening on an Avalon N8-90 thermal platesetter (all from AGF ANV). 2 All plates were exposed to the same test image at 2400 dpi.

[0117] After linearization and calibration curves for the plates were established, the plates were made.

[0118] Without any off-press processing, the exposed printing plates were mounted on a Heidelberg Speedmaster XL 106 printing press equipped with an automatic AutoPlate plate changing system and an integrated Prinect Inpress control system (all trademarks of Heidelberg Druckmaschinen, Germany). The integrated Prinect Inpress control system automates the press set-up process by registering the printed image and measuring color data instantly, which is used to reposition the plates and adjust the ink key as needed. Each printing run used K+E Novaboard 4C 1090 Race Bio CMYK ink (a trademark of the Flint Group), and as the dampening solution 3% by volume of Saphira Fount 221 AF (a trademark of Heidelberg Druckmaschinen, Germany) and 6.4% by volume of isopropanol in water. 115 g / m 2 coated paper as a receptor material. The press speed used in all examples was 13,000 sheets per hour. Completion of the press set-up process was established when the color density of the image was within the ΔE tolerance range as specified in ISO standard 12647-2 (2013).

[0119] Print result Run 1: Five hundred new, unprinted sheets were placed face up in the press feed section and printing of Image 1 and Color Bar-01 was started. After printing approximately 180 sheets, the press set-up process was completed with a spectral measurement system, Prinect Inpress Control, available from Heidelberg, to obtain the desired color of the image. The press was then stopped. Run 2: 200 new, unprinted sheets were placed face up in the press feed section, and the 180 printed sheets from Run 1 were placed face up on top of these new sheets in the same orientation as in Run 1. Printing of Image 2 and Color Bar-02 began. Color Bar-01 was neutralized by exposing a neutralization image to a printing master prepared for the black printing station at the location of Color Bar-01 on the printed sheets. The color bar-02 was recognized by the detector of the printing press and after printing about 190 sheets, it was measured by the spectral measurement system Prinect, available from Heidelberg. The press setup process was completed using Inpress Control to achieve the desired image color. The press was then shut down. At this point, after Run 1 and Run 2 were run together, only 190 waste sheets had been generated. Run 3: 200 new, unprinted sheets were placed face up in the press feed section, and the 190 printed sheets of Run 2 were placed back on top of these new sheets. Printing of Image 3 and Color Bar-03 began. Color Bar-02 was neutralized by exposing a neutralization image to a printing master prepared for the black printing station at the location of Color Bar-02 on the printed sheets. Colorbar-03 was recognized by the detector of the printing press and measured after printing approximately 185 sheets using the spectral measurement system Prinect, available from Heidelberg. The press setup process was completed in Inpress Control to achieve the desired image color. The press was shut down. At this point, after Run 1, Run 2, and Run 3 were run together, only 190 waste sheets were generated.

[0120] conclusion During the three runs of the method of the present invention, a total of only about 190 wasted sheets were generated. Under a standard printing regime, about 555 sheets would have been wasted: 180 sheets for the setup of Run 1; 190 sheets on the setup for Run 2; 185 sheets on the setup for execution 3; In summary, significant paper savings of over 65% were obtained after three press runs using the method of the present invention.

Claims

1. 1. A method of setting up a lithographic printing press having at least one printing station having an inking unit and a plate cylinder, comprising: The method comprises the steps of: (a) preparing a lithographic printing blank by exposing said printing blank to an image in an area and color bar CB-02 outside said area; (b) mounting the exposed master on the plate cylinder of the printing press; (c) executing a setup process for the printing press to bring it to a production quality defined by target color data on printed copies produced by the printing press, the printing press setup process including the steps of: (ci) feeding multiple sheets through said printing press, thereby producing printed copies of said image and said color bar CB-02. (c-ii) measuring color data of the color bar on the printed copy, and adjusting the inking unit according to differences between the measured color data and the target color data. (c-iii) repeating steps (c-i and c-ii) until the measured color data matches the target color data; and Including, the sheet fed through the printing press in step (c-i) has already been used in the press setup process for another printing run and includes at least a previous color bar CB-01 at a position on the printed copy that is different from the position of the color bar CB-02 exposed in step (a); The method.

2. The method of claim 1, wherein the color bar CB-01 and the color bar CB-02 are printed on the same side of the sheet.

3. The method of claim 1 or 2, wherein the color bar CB-01 is disabled before step c(ii) of the press setup process.

4. 4. The method according to claim 1, wherein in step (a), the color bar CB-01 is neutralized by exposing a neutralization image to the printing plate at a position corresponding to the position of the color bar on the printed copy.

5. The method of claim 4, wherein the nullification image covers a recognition patch of the color bar CB-01.

6. 10. A method according to any one of the preceding claims, wherein the printing press comprises at least four printing stations, and wherein the color bar CB-01 is disabled at one of the four printing stations.

7. 3. The method of claim 1 or 2, wherein the color bar CB-01 has been invalidated at the end of the press setup process of the previous print run by manual invalidation of the color bar on the printed copy and / or by a separate invalidation device.

8. 10. The method according to any one of the preceding claims, wherein the color bar CB-01 and the color bar CB-02 are oriented along a direction (X) parallel to the axis of the plate cylinder of the printing press.

9. 10. A method according to any one of the preceding claims, wherein the sheet fed through the printing press in step (ci) is a sheet that has already been printed in more than one previous printing run and has at least three color bars.

10. 10. The method of claim 1, wherein the printing press is equipped with an automatic press control system, the automatic press control system including an integrated system for detecting and measuring color data of the color bar on the printed copies and modifying the color data on the printed copies by adjusting the inking units.

11. 11. The method of claim 10, wherein the automatic printing press control system comprises a detection device and a measurement device as two separate devices provided at different positions on the printing press, and wherein the color bar CB-01 is disabled before detecting the color bar CB-02.

12. 12. The method of claim 11, wherein the detection device is provided between a first and a last printing station of the printing press, and the measurement device is provided after the last printing station of the printing press.

13. 10. The method according to any one of the preceding claims, wherein the printing master is developed before step (b).

14. 10. The method of any one of the preceding claims, wherein the printing plate is developed on the printing press during the press setup process.

15. 15. The method of claim 13 or 14, wherein the printing master comprises a photopolymerizable or photocrosslinkable image-recording layer.

Images