Lithographic printing plate precursor and method for providing a lithographic printing plate

Abstract

IR-sensitive lithographic printing plate precursors provide stable print-out images using a unique IR radiation-sensitive composition in the IR radiation-sensitive image-recording layer. The IR radiation-sensitive composition comprises: (1) a free radical initiator composition comprising a borate compound; (2) a free radical polymerizable composition; (3) an acid-sensitive color change compound represented by Formula (I) identified herein; (4) an infrared absorber material; and (5) a color change compound of Formula (III) or Formula (IV) identified herein. After IR imaging, the exposed precursors exhibit desirable print-out images, especially in the 600-700 nm region of the electromagnetic spectrum, and especially for viewing using electronic sensing devices. The imaged precursors can be developed off-press or on-press.

Description

Technical Field

[0001] This invention relates to infrared radiation-sensitive lithographic printing plate precursors that can be imaged using infrared radiation to provide an imaged lithographic printing plate. Such precursors comprise a unique infrared radiation-sensitive composition that provides a stable and more easily detectable printout image between exposed and unexposed areas in an image-wise exposed infrared radiation-sensitive image recording layer. The invention also relates to methods for using these precursors to provide lithographic printing plates with excellent printout images. Background Technology

[0002] In offset printing, offset ink-receiving areas, known as image areas, are created on a hydrophilic surface of a planar substrate, such as an aluminum-containing substrate. When the printing plate surface is wetted with water and offset printing ink is applied, the hydrophilic areas retain water and repel the offset printing ink, while the offset ink-receiving image areas accept the offset printing ink and repel water. Alternatively, in the case of using a blanket roller in a printing press, offset printing ink is transferred to the surface of the material on which the image is to be reproduced.

[0003] Negative plate-making precursors used to prepare lithographic printing plates typically comprise a radiation-sensitive image recording layer disposed on a hydrophilic surface of a substrate. This image recording layer contains a radiation-sensitive component that can be dispersed in a suitable polymeric binder material. After the precursor is exposed to suitable radiation to form exposed and unexposed areas in the image recording layer, the unexposed areas are removed in a suitable manner, exposing the hydrophilic surface of the underlying substrate. The exposed areas of the retained image recording layer are lithographic ink-receptive, and the hydrophilic substrate surface exposed by the development process accepts water and aqueous solutions such as dampening solutions, while repelling lithographic inks.

[0004] In recent years, there has been an increasing demand in the lithographic printing industry for simplifying the manufacture of lithographic printing plates by using lithographic inks or dampening solutions or both for in-machine development (“DOP”) to remove unexposed areas of the image recording layer.

[0005] Therefore, in recent decades, machine-developable lithographic printing plate precursors have gained increasing attention in the printing industry due to their numerous advantages over conventionally rinsed (“off-machine” rinsed or developed) lithographic printing plate precursors, including less environmental impact and savings in rinsing chemicals, rinse machine footprint, and operating and maintenance costs. Machine-developable precursors can be brought directly to the printing press after laser imaging without any pre-wet chemical steps to remove the imageable coating from the precursor in non-printing areas.

[0006] It is highly desirable for such an imaged lithographic printing plate precursor to have different colors between the exposed and unexposed areas. The color difference or "contrast" between the exposed and unexposed areas is often referred to as the "print output" or "print output image." A strong print output will facilitate the operator's visual evaluation and identification of the imaged printing plate precursor, allowing it to be properly attached to the printing press unit.

[0007] Many methods have been employed to enhance the print output of machine-developable printing plates. Each has its advantages and disadvantages, and further improvements would be beneficial.

[0008] For example, print output on an IR-sensitive lithographic printing plate precursor exposed to an imaging composition containing an acid-generating agent and an acid-sensitive color precursor, such as a lactone-based colorless dye, is often insufficiently strong due to the limited efficiency of acid generation in imaging compositions designed for in-machine development. Furthermore, the concentration of protons generated during infrared radiation imaging typically decreases after imaging through chemical equilibrium or other post-imaging chemical reactions. As a result, print output based on proton-induced color changes often fades after imaging.

[0009] Furthermore, using a more sensitive color composition inevitably increases the lithographic printing plate precursor's sensitivity to white light. If this precursor is exposed to white light after imaging, this increased white light sensitivity will result in increased color formation in non-imaging areas. This undesirable result reduces contrast and decreases the readability of the printed image.

[0010] U.S. Patent Application Publication 202I / 0078350 (Viehmann et al.) describes efforts to enhance print output by incorporating more sensitive coloring compounds, which transform from colorless to colored forms at lower acid concentrations, into infrared radiation-sensitive imaging compositions. Background color formation is suppressed by special additives to stabilize good contrast. Initial print output obtained using certain colorless dyes in imaging chemistry is quite high, but further improvements in print output stability (reduced fading) are a desired goal in industry. More specifically, strong print output perceived by the human eye is not always strong enough to be detected by electronic reading devices such as cameras or sensors used to read barcodes, QR codes, data matrices, or other images to provide information for automated processes required for plate picking after imaging and before punching and bending, or for automated plate loading into the printing unit.

[0011] Many electronic reading devices used in the market have laser diodes as light sources, with emission peaks between 600 nm and 700 nm. For example, many printing presses manufactured by Koenig & Bauer (KBA) and used by numerous lithographic printing companies are equipped with a plate recognition system called DriveTronic Plate Ident, which ensures that lithographic printing plates are mounted on the printing press in the correct position and sequence. The DriveTronic Plate Ident system is a camera-based system that enables the proper positioning of lithographic printing plates during fully automated plate changes. The camera used in the DriveTronic Plate Ident system has an internal light source that emits at approximately 620 nm. Typically, the camera in the DriveTronic Plate Ident system can read printing plates with a large difference in reflectance absorbance at 620 nm between the imaging and non-imaging areas well. On the other hand, colored compounds formed from highly acid-sensitive coloring compounds, as taught in the aforementioned publication by Viehmann et al., have relatively low absorbance in this spectral region and cannot provide a large difference in reflectance absorbance at 620 nm between the imaging and non-imaging areas. Due to this mismatch between the emission and absorption peaks, despite the presence of relatively high ΔE values ​​useful for human visual perception, printed output images in such image recording layer compositions cannot be easily detected by conventional electronic reading devices on the market.

[0012] Therefore, there is a need for an infrared-sensitive lithographic printing plate precursor containing an acid-sensitive coloring compound, which not only has high acid sensitivity but is also capable of forming a colored compound with strong absorption in the spectral range between 600 nm and 700 nm.

[0013] Overview of the invention

[0014] This invention provides a lithographic printing plate precursor, comprising:

[0015] Base, and

[0016] An infrared radiation-sensitive image recording layer disposed on the substrate, the infrared radiation-sensitive image recording layer comprising the following components (1), (2), (3), (4) and (5):

[0017] (1) A free radical initiator composition that is capable of generating free radicals upon exposure to infrared radiation and contains a borate compound;

[0018] (2) Free radical polymerizable compositions;

[0019] (3) Acid-sensitive color-changing compounds, represented by the following formula (I):

[0020]

[0021] in:

[0022] Ar 1 For substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups;

[0023] R 1 and R 2 Independently hydrogen, substituted or unsubstituted alkyl groups each having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups, or R 1 and R 2 They can be connected to form fused rings;

[0024] R 3 It is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group having 1 to 12 carbon atoms;

[0025] R 4 and R 5 Independently hydrogen, substituted or unsubstituted alkyl groups each having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups; and

[0026] R 6 and R 7 Independently hydrogen, or substituted or unsubstituted alkyl groups having 1 to 12 carbons.

[0027] Or R 4 and R 6 They can be connected together to form a ring structure, or R 5 and R 7 They can be connected together to form a ring structure, or R 4 and R 5 One or both can be associated with R respectively 6 and R 7 connect;

[0028] (4) Infrared absorbing materials; and

[0029] (5) Color-changing compounds represented by formula (III) or formula (IV):

[0030]

[0031] in:

[0032] Ar1', Ar2', and Ar3' independently represent the atoms required to complete a substituted or unsubstituted aromatic ring or a heteroaromatic ring;

[0033] Y represents an oxygen atom, a sulfur atom, or a substance derived from >C(R). 4’ R 5’ ) represents a dialkylmethylene, wherein R 4’ and R 5’ Each is an alkyl group, whether substituted or unsubstituted, having 1 to 4 carbon atoms.

[0034] R” is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl;

[0035] R 1’ and R 2’ Independently substituted or unsubstituted alkyl groups;

[0036] X represents a single bond or is selected from -S-, -O-, and >N(R). 6’ The divalent linking group of ) wherein R 6’ It is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, or L;

[0037] L represents -C(=O)-OR 7’ Group, -SO2-R 3’ Group or -SO2NR 8’ R 9’ Group, wherein R 7’ Indicates substituted or unsubstituted alkyl groups having the following properties: -C(=O)OR 7’ The remaining portion of the group is connected to a secondary or tertiary carbon; and R 3’ R 8’ and R 9’ Independently representing a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; R 7’ It is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl;

[0038] A 1 and A 2 Independently representing substituted or unsubstituted alkyl groups, or together representing the two or three carbon atoms required to form a substituted or unsubstituted 5- or 6-membered non-aromatic carbon ring; and

[0039] Za represents one or more counterions to balance the charge in the remainder of the color-changing compound according to formula (III) or (IV), and

[0040] The borate compound is represented by the following formula (VI):

[0041] [B(R 10’ R 11’ R 12’ R13’ ) - ] n M n+

[0042] Formula (VI)

[0043] Where R 10’ R 11’ R 12’ and R 13’ Independently, it is a substituted or unsubstituted alkyl or a substituted or unsubstituted aryl group, and R 10’ R 11’ R 12’ and R 13’ At least three of them are substituted or unsubstituted aryl groups; M n+ It is an n-valent cation, and n is a positive integer.

[0044] The present invention also provides a method for providing a lithographic printing plate, the method comprising:

[0045] A) Expose the lithographic printing plate precursor according to any embodiment of the present invention to infrared radiation to provide exposed and unexposed areas in the infrared radiation-sensitive image recording layer, and

[0046] B) Remove the unexposed areas from the infrared radiation-sensitive image recording layer.

[0047] This invention provides strong printed output images in regions of infrared radiation-sensitive image recording layers exposed to relatively low-energy imaging infrared radiation. For example, even at 120 mJ / cm² or less. 2 Under infrared radiation exposure, a difference of at least 0.02 in reflectance absorption between the infrared radiation exposed area and the infrared radiation unexposed area after infrared radiation exposure (step A in the method of the present invention) can also be achieved.

[0048] The strong printed output image is visible to the human eye and to various electronic sensors frequently used by printing press operators in the offset printing industry.

[0049] These advantages are achieved through the presence of certain acid-sensitive color-changing compounds in a colorless form, identified herein by formula (I), and certain color-changing compounds represented by formula (III) or (IV). These compounds possess two unique properties: (a) the ability to form desired print output colors with sufficient absorption in their colored form between 600 nm and 700 nm; and (b) the ability to provide strong print output due to the high extinction coefficient of this colored form and its high sensitivity to acid-induced conversion from the colorless to the colored form. The combination of structural features of these compounds provides these desirable advantages of the present invention.

[0050] Detailed description of the invention

[0051] definition

[0052] Unless the context otherwise indicates, the terms “lithographic printing plate precursor,” “precursor,” and “IR-sensitive lithographic printing plate precursor” are used herein as equivalent references to embodiments of the invention.

[0053] As used herein, the term "infrared radiation absorber" refers to a compound or material that absorbs electromagnetic radiation in the near-infrared (near IR) and infrared (IR) regions of the electromagnetic spectrum, and it generally refers to a compound or material that has maximum absorption in the near IR and IR regions.

[0054] As used herein, the terms "near-infrared region" and "infrared region" refer to radiation with wavelengths of at least 750 nm and higher. In most cases, the term is used to refer to the region of the electromagnetic spectrum with wavelengths of at least 800 nm and at most 1400 nm.

[0055] For the purposes of this invention, the intensity of the printed output image is typically represented by ΔE, which is the Euclidean distance between the colors of the infrared radiation exposed region and the infrared radiation unexposed region in the CIE 1976 L*A*B* color space. ΔE is measured according to ENISO 11664-4 "Colorimetry—Part 4: CIE 1976 L*a*b*Colour space." and other known references, using a CIE 2° observer and a D50 as the light source from a 45 / 0 geometric (unpolarized) reflectance measurement. Color measurements can be performed using commercially available instruments such as the Techkon SpectroDens. In the CIE 1976 L*a*b color space, color is represented by three numerical color values: L* represents the lightness (or brightness) of the color, a* represents the green-red component of the color, and b* represents the blue-yellow component of the color value.

[0056] Another parameter that can be used for the purposes of this invention is optical density (OD) or the difference in optical density ΔOD, especially ΔOD. 青色 According to DIN 16536, it can be determined by the same apparatus as described above or by other commercially available spectral density meters.

[0057] For the purposes of this invention, the visible spectrum region refers to the spectral region of electromagnetic radiation with wavelengths from 400 nm to 700 nm.

[0058] Unless otherwise specified, the term "wt%" refers to the amount of component or material based on the total solids of a composition, formulation, or layer. Unless otherwise specified, the percentage may be the same for a dried layer or total solids of a formulation or composition.

[0059] As used herein, the term "layer" or "coating" may consist of a single layer that is set or applied or a combination of several layers that are set or applied in sequence. If a layer is considered to be both infrared-sensitive and negative-forming, then it is both sensitive to infrared radiation (as described above regarding "infrared radiation absorbers") and negative-forming in the formation of a lithographic printing plate.

[0060] As used herein, the terms “machine-developable” and “machine-developable” refer to the ability of a precursor according to the invention to be developed after infrared radiation exposure (imaging) by mounting the imaging precursor on a suitable printing press and developing it using dampening solution, lithographic ink, or a combination of dampening solution and lithographic ink during the first few printing runs.

[0061] use

[0062] The lithographic printing plate precursors according to the invention can be used to provide lithographic printing plates that exhibit a desired printed output image after exposure to infrared radiation. These lithographic printing plates can be used for lithographic printing during printing press operation. According to the invention, lithographic printing plates can be prepared using in-machine washing or off-machine washing after infrared radiation exposure. The lithographic printing plate precursors are prepared using the structure and components described below.

[0063] Pre-printing plate for lithography

[0064] The precursor according to the invention can be formed by suitably applying an infrared radiation-sensitive image recording composition (described below) to a suitable substrate (described below) to form an infrared radiation-sensitive image recording layer for negative lithography. Typically, the infrared radiation-sensitive image recording composition (and the resulting infrared radiation-sensitive image recording layer) comprises four essential components: component (1) a radical initiator composition capable of generating radicals and protons upon exposure of the infrared-sensitive imaging recording composition to infrared radiation; component (2) a radical-polymerizable composition; component (3) an acid-sensitive color-changing compound represented by formula (I) below; component (4) an infrared absorbing material (or a mixture of two or more thereof); and component (5) a color-changing compound represented by formula (III) or (IV). All these components (1), (2), (3), (4), and (5) are defined in detail below, and these components are the only necessary components required to achieve the advantages of the invention.

[0065] In some embodiments, the infrared radiation-sensitive image recording composition (and the resulting infrared radiation-sensitive image recording layer) may further comprise a component (6) of a non-radical polymeric material (or a mixture of two or more thereof) different from all components (1), (2), (3), (4), and (5). In some highly useful embodiments, the infrared radiation-sensitive image recording layer is substantially composed of all said components (1) to (6) to provide a desired lithographic printing plate precursor with a desirable printed output image and optimal overall imaging and printing properties.

[0066] Each precursor of the present invention typically includes an infrared radiation-sensitive image recording layer as the outermost layer of the precursor, but in some embodiments, an outermost water-soluble hydrophilic protective layer (also known as a topcoat or oxygen barrier layer) may be present above (or directly on and in contact with) the infrared radiation-sensitive image recording layer.

[0067] base

[0068] The substrate used to prepare the precursor according to the invention typically has a hydrophilic imaging-side surface, or a surface that is at least more hydrophilic than the applied infrared radiation-sensitive image recording layer. The substrate typically comprises an aluminum-containing carrier, which may contain primary aluminum or a suitable aluminum alloy conventionally used for preparing lithographic printing plate precursors.

[0069] Aluminum-containing substrates can be treated using techniques known in the art, including roughening by physical (mechanical), electrochemical, or chemical grinding, followed by one or more anodizing processes. Each anodizing process typically uses phosphoric acid or sulfuric acid and conventional conditions to form the desired hydrophilic alumina (or anodic oxide) layer on the aluminum-containing carrier. A single alumina (anodic oxide) layer may be present, or multiple alumina layers may be present (e.g., an inner alumina layer and an outer alumina layer disposed on the inner alumina layer), each anodic layer having multiple pores with pore openings of varying depths and shapes. Thus, such an anodizing process provides an anodic oxide or alumina layer beneath an infrared radiation-sensitive image recording layer (which may be provided below). For example, discussions of such pores and methods for controlling their width and depth are provided in U.S. Patent Publications 2013 / 0052582 (Hayashi), 2014 / 0326151 (Namba et al.), and 2018 / 0250925 (Merka et al.), as well as U.S. Patents 4,566,952 (Sprintschnik et al.), 8,789,464 (Tagawa et al.), 8,783,179 (Kurokawa et al.), and 8,978,555 (Kurokawa et al.), and EP 2,353,882 (Tagawa et al.). Teachings regarding providing two or more consecutive anodizing processes to provide different alumina layers in a substrate are described, for example, in U.S. Patent Application Publication 2018 / 0250925 (as described above), U.S. Patent Application Publication 2021 / 0094336 (Merka et al.), and U.S. Patent 4,865,951 (Huddleston et al.).

[0070] Known post-anodizing methods, such as post-treatment with an aqueous solution of a hydrophilic material, can be used to further treat the anodized aluminum-containing substrate to seal the anodic oxide pores or to hydrophilize its surface, or both. Representative hydrophilic materials of this type that provide hydrophilic layers (or hydrophilic polymer coatings) include, but are not limited to, poly(vinylphosphonic acid) (PVPA), vinylphosphonic acid copolymers, poly[(meth)acrylic acid] or its alkali metal salts, or (meth)acrylic acid copolymers or their alkali metal salts, phosphate and fluoride salts, or sodium silicate. Such hydrophilic coatings can be applied to the outermost alumina layer (e.g., an outer alumina layer if multiple alumina layers are present). Useful post-treatment methods include impregnation of the substrate with rinsing, impregnation of the substrate without rinsing, and various coating techniques such as extrusion coating.

[0071] Some useful hydrophilic polymer coating materials include: one or more hydrophilic polymers, at least one of which is a hydrophilic copolymer comprising at least (a) repeating units containing amide units, and (b) repeating units containing -OM' groups directly attached to phosphorus atoms, wherein M' represents hydrogen, sodium, potassium, or aluminum atoms. This hydrophilic layer can achieve a coating density of at least 0.0002 g / m³. 2 And at most 0.1g / m 2 The dry coating is applied to the outermost alumina layer.

[0072] The thickness of the substrate can vary, but it should be sufficient to withstand the wear and tear from printing and thin enough to wrap around the printed form.

[0073] The substrate can be formed into a continuous roll (or continuous web) of sheet material, which is suitably coated with an infrared radiation-sensitive image recording layer formulation and an optional hydrophilic protective layer formulation, and then slitting or cutting (or both) to a certain size to provide a separate lithographic printing plate precursor having a shape or form with four right-angled corners (therefore, it is usually planar or generally flat, and is a square or rectangular shape or form).

[0074] Infrared radiation-sensitive image recording layer:

[0075] The infrared radiation-sensitive image recording layer composition (and the infrared radiation-sensitive image recording layer prepared therefrom) according to the invention is designed as “negative plate making,” as the term is known in the field of lithography. Furthermore, the infrared radiation-sensitive image recording layer can be designed to have a certain combination of components to provide machine developability to a lithographic printing plate precursor after exposure, for example, enabling machine development using dampening solutions, lithographic printing inks, or a combination of both.

[0076] This invention utilizes a component (1) radical initiator composition capable of generating radicals and protons upon exposure of an infrared-sensitive image recording layer to infrared radiation. Such a component (1) radical initiator composition may comprise one or more organohalogen compounds, such as trihaloalkyl compounds; halomethyltriazines; bis(trihalomethyl)triazines; or one or more onium salts, such as iodonium salts, sulfonium salts, many of which are known in the art to generate radicals and protons upon exposure to infrared radiation of an infrared-absorbing composition containing such compounds. Representative compounds other than onium salts are described, for example, in U.S. Patent Application Publication 2005 / 0170282 (Inno et al., US'282)

[0087] to

[0102] and U.S. Patent 6,309,792 (Hauck et al.) (which includes numerous cited publications describing such compounds), as well as Japanese Patent Publication 2002 / 107916 and WO 2019 / 179995.

[0077] For example, the radical initiator composition of component (1) may contain an onium salt, such as an iodonium cation or a sulfonium cation, or both. Useful onium salts are described, for example, in U.S. Publication '282's

[0103] to

[0109] . For example, useful onium salts contain at least one onium cation and a suitable anion in the molecule. Examples of onium salts include triphenylsulfonium and diphenyliodonium salts and their derivatives obtained by introducing one or more substituents into the benzene ring of these compounds. Onium cations particularly useful for onium salts include iodonium cations, such as diaryliodonium cations, for example having two substituted or unsubstituted phenyl groups.

[0078] Examples of anions in onium salts include, but are not limited to, halide anions and ClO4. - PF6 - BF4 - SbF6 - CH3SO3 - CF3SO3 - C6H5SO3 - CH3C6H4SO3 - HOC6H4SO3 - ClC6H4SO3 - And boron anions, as described, for example, in U.S. Patent 7,524,614 (Tao et al.). Representative useful iodonium salts are described in columns 6-7.

[0079] Furthermore, the ononium salts described in paragraphs

[0033] to

[0038] of the specification of Japanese Patent Publication 2002-082429 [or U.S. Patent Application Publication 2002-0051934 (Ippei et al.)] are useful. Representative iodonium borates are listed, for example, in column 8 of U.S. Patent 7,524,614 (as described above).

[0080] In some embodiments, combinations of onium salts can be used as part of component (1) a free radical initiator composition, such as combinations of compounds described in U.S. Patent Application Publication 2017 / 0217149 (Hayashi et al.).

[0081] (1) The free radical initiator composition shall contain one or more borate compounds. Some useful borate compounds can be represented by the following formula (VI):

[0082] [B(R 10’ R 11’ R 12’ R 13’ ) - ] n M n+

[0083] Formula (VI)

[0084] Where R 10’ R 11’ R 12’ and R 13’ Independently, it is a substituted or unsubstituted alkyl group (each having 1 to 12 carbon atoms and may be straight-chain or branched) or a substituted or unsubstituted aryl group (e.g., substituted or unsubstituted phenyl or naphthyl), and R 10’ R 11’ R 12’ and R 13’ At least three of them are the same or different substituted or unsubstituted aryl groups (e.g., substituted or unsubstituted phenyl groups); M n+ It is an n-valent cation, where n is a positive integer. Tetraphenylborate is particularly useful.

[0085] The component (1) free radical initiator composition is present in the infrared radiation sensitive image recording layer in an amount (molar or weight ratio) that will be obvious to those skilled in the art of preparing machine-developable lithographic printing plate precursors, and the minimum and maximum total amount is generally at least 1% by weight and at most 20% by weight of all materials, based on the total coverage (solids) of the infrared radiation sensitive image recording layer.

[0086] Since the component (1) radical initiator composition can have a variety of materials, it will be apparent to those skilled in the art, based on their knowledge and the representative teachings provided herein (including the working examples shown below), that the useful amount or dry coverage of the various materials of the component (1) radical initiator composition in an infrared radiation-sensitive image recording layer is appropriate.

[0087] A second essential feature of the infrared radiation-sensitive image recording layer is a component (2) of a radical-polymerizable composition comprising one or more radical-polymerizable components, each containing one or more radical-polymerizable groups that can be polymerized using radical initiation during infrared radiation exposure. In some embodiments, at least two radical-polymerizable components are present, each having the same or different numbers of radical-polymerizable groups in each molecule. Thus, a useful (2) radical-polymerizable composition may comprise one or more radical-polymerizable monomers or oligomers having one or more polymerizable olefinic unsaturated groups (e.g., two or more such groups). Similarly, crosslinkable polymers having such radical-polymerizable groups may also be used. Oligomers or prepolymers may be used, such as polyurethane acrylates and methacrylates, epoxy acrylates and methacrylates, polyester acrylates and methacrylates, polyether acrylates and methacrylates, and unsaturated polyester resins.

[0088] (2) One or more materials in the free radical polymerizable composition may have a sufficiently large molecular weight or sufficient polymerizable groups to provide a crosslinkable polymer matrix that functions as a “polymer binder” for other materials in an infrared radiation-sensitive image recording layer. In such embodiments, different (6) non-free radical polymerizable polymer materials (described below) are not required, but may still be present if desired.

[0089] (2) The useful material in the free radical polymerizable composition may include urea polyurethane (meth)acrylate or polyurethane (meth)acrylate having a plurality of (two or more) polymerizable groups. For example, it can be made by making triisocyanate, for example N100 (Bayer Corp., Milford, Conn.) or by reacting diisocyanates such as hexane-1,6-diisocyanate with hydroxyethyl acrylate, pentaerythritol triacrylate, or dipentaerythritol pentaacrylate to prepare polyurethane acrylates having at least two and at most fifteen acrylate groups. Such polyurethane or urea (meth)acrylate compounds have up to fifteen or more (meth)acrylate groups per molecule. Commercially available polyurethane acrylates having fifteen acrylate groups include U-15HA and UA-53H, which are available from Shin-Nakamura Chemical Co. Ltd. These compounds having a large number of (meth)acrylate groups can be included in the radically polymerizable composition described in (2) due to their high crosslinking efficiency.

[0090] Other useful materials in (2) free radical polymerizable compositions may include non-polyurethane and non-urea (meth) acrylates derived from polyfunctional alcohols, such as NK Ester A-DPH (dipentaerythritol hexaacrylate) available from Kowa American, and Sartomer SR399 (dipentaerythritol pentaacrylate), Sartomer 355 (di-trimethylolpropane tetraacrylate), Sartomer SR295 (pentaerythritol tetraacrylate), Sartomer SR415 [ethoxylated (20)trimethylolpropane triacrylate], and Sartomer SR494 (ethoxylated pentaerythritol tetraacrylate) available from Sartomer Company, Inc.

[0091] Polyurethanes or urea (meth)acrylates, as well as mixtures of non-polyurethanes and non-urea (meth)acrylates, can be used in (2) free radical polymerizable compositions. In some embodiments, mixtures of compounds with different numbers of (meth)acrylate groups can be used.

[0092] (2) Many other materials in free radical polymerizable compositions are known in the art and described in a large number of documents, including Photoreactive Polymers: The Science and Technology of Resists A. Reiser, Wiley, New York, 1989, pp. 102-177, BM Monroe Radiation Curing: Science and Technology In Sp. P. Appas, ed., Plenum, New York, 1992, pp. 399-440, and in A.B. Cohen and P. Walker, “Polymer Imaging”. Imaging Processes and Materials In JMSturge et al. (eds.), Van Nostrand Reinhold, New York, 1989, pp. 226-262. For example, useful radical polymerizable components are also described in EP 1,182,033A1 (Fujimaki et al.) (starting from paragraph

[0170] ) and U.S. Patents 6,309,792 (Hauck et al.), 6,569,603 (Furukawa), and 6,893,797 (Munnelly et al.). Other useful radical polymerizable components include those described in U.S. Patent Application Publication 2009 / 0142695 (Baumann et al.).

[0093] The material in component (2) of the free radical polymerizable composition is generally present in a total amount of at least 10% by weight or at least 20% by weight and at most 50% by weight or at most 70% by weight, all based on the total coverage (solids) of the infrared radiation sensitive image recording layer.

[0094] The third essential component of the infrared radiation-sensitive image recording composition and image recording layer according to the present invention is component (3) an acid-sensitive color-changing compound, or a mixture of two or more thereof, each represented by the following formula (I):

[0095]

[0096] The three distinguishing features of formula (I) based on pyrazine or 4,7-diazaphthalide colorless dyes are the two nitrogen atoms and R in the fused heterocyclic group on the left side of the structure. 3The oxygen bond with the benzyl ring. The overall chemical structure of formula (I) provides sufficiently strong absorption in its colored form (as its protonated form) over a wavelength range of at least 575 nm and at most 750 nm, and thus enables a large difference in reflectance absorbance between the imaging and non-imaging areas of the infrared radiation-sensitive image recording composition and the image recording layer at the emission wavelength of the light source used by the camera in the printing press automation system, for example, 620 nm for the KBA DriveTronic Plate Identification system. The reflectance absorbance at a given wavelength is defined as log 10 (I r / I i ), where I i It is the light intensity of the incident light, I r It is the light intensity reflected from the surface of the sample, for example, the surface of a lithographic printing plate precursor in an infrared radiation exposure area or an infrared radiation non-exposure area, and log 10 Represented as a logarithmic function based on 10. Reflectance absorbance can be measured using commercially available reflectance measurement devices, such as the Techkon SpectroDens device available from TECHKON GmbH. For compatibility with printing press automation systems such as the KBA DriveTronic Plate Identification system, the difference in reflectance absorbance at 620 nm between the infrared-exposed and infrared-unexposed areas of the imaged lithographic printing plate precursor is typically at least 0.02, and more preferably at least 0.05.

[0097] To ensure sufficiently strong absorption within the electromagnetic spectrum wavelength range of at least 575 nm and at most 750 nm, the maximum absorption wavelength (λ) of the compound in its colored form is required. 最大 The peak absorption is typically in the range of at least 575 nm and at most 750 nm. In some embodiments, sufficiently strong absorption (peak or non-peak wavelength) is provided in the wavelength range of at least 600 nm and at most 700 nm, and even more preferably, the maximum absorption wavelength (λ) of the compound in its colored form when the lactone ring is open in the presence of a proton. 最大 (or peak absorption) is in the range of at least 600 nm and at most 700 nm. These compounds have the ability to provide strong printing output, which is driven by the high extinction coefficient of the colored form of the compound and the high sensitivity of the acid-induced conversion from the colorless form to the colored form.

[0098] More specifically, in formula (I), Ar1 is a substituted or unsubstituted aryl or a substituted or unsubstituted heteroaryl (as defined below). For example, Ar1 can be a substituted or unsubstituted benzyl or naphthyl. Substituents useful for such groups include, but are not limited to, alkyl, alkoxy, halogen, cyano, -COOR', -SO3R', and -SO2R' groups, where R' represents a substituted or unsubstituted alkyl (including straight-chain and branched alkyl) having 1 to 12 carbon atoms, and any said substituents may be further substituted.

[0099] Useful substituted or unsubstituted heteroaryl groups include, but are not limited to, substituted or unsubstituted pyridin-2-yl, pyridin-3-yl, pyridin-4-yl, pyridazinyl, pyrimidin-2-yl, pyrimidin-4-yl, pyrimidin-5-yl or pyrimidin-6-yl, pyrazinyl, triazinyl, pyrroleyl, furanyl, phenylthio, pyrazolyl, oxazolyl, imidazolyl, thiazolyl, and triazolyl. Useful substituents for these heteroaryl groups include those listed above for the aryl groups.

[0100] The Ar1 groups that are particularly useful are those shown in the following three parts:

[0101]

[0102] Where R 3 R 4 R 5 R 6 and R 7 As specified below, and R 8 R 9 and R 10 It is independently hydrogen, or a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms (including straight-chain and branched alkyl groups).

[0103] In equation (I), R 1 and R 2 The alkyl group is independently hydrogen or substituted or unsubstituted, each having 1 to 6 carbon atoms, or even 1 to 12 carbon atoms, and includes straight-chain and branched acyclic alkyl groups. In many embodiments, one or both of such substituted or unsubstituted alkyl groups may contain the same or different ether or ester groups inserted into the carbon chain, or, in the case of ester groups, they may be used to terminate the alkyl chain. Optional substituents on the alkyl group may be limited to the optional substituents described above for Ar1.

[0104] R 1 and R 2It can also be independently a substituted or unsubstituted aryl group having 6 or 10 carbon atoms in the aromatic ring, or a substituted or unsubstituted heteroaryl group having 5 to 10 carbon atoms and heteroatoms in the heteroaromatic ring. The substituent can be any of those described above for substituted alkyl groups.

[0105] In addition, R 1 and R 2 These rings can be linked to form fused rings, which are connected to aromatic rings. Such rings can be aromatic or non-aromatic and can contain any number of atoms that are chemically possible and usable in this invention. These fused rings can be unsubstituted or substituted with one or more substituents as described above for alkyl groups.

[0106] In addition, R 3 It is a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms (or 1 to 6 carbon atoms), including straight-chain or branched alkyl groups, or a substituted or unsubstituted aryl group (e.g., substituted or unsubstituted phenyl or naphthyl), or a substituted or unsubstituted heteroaryl group (e.g., the substituted or unsubstituted groups described above). Useful substituted or unsubstituted alkyl groups and optional substituents may have the same characteristics as described above for R. 1 and R 2 The same definitions as those described above apply. Useful aryl and heteroaryl groups and optional substituents may have the same definitions as those described above for Ar1.

[0107] R 4 and R 5 Independently hydrogen, substituted or unsubstituted alkyl groups having 1 to 12 carbon atoms (or 1 to 6 carbon atoms), substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups, said groups and optional substituents may have the same characteristics as described above for R. 1 and R 2 The same definitions mentioned above.

[0108] R 6 R 7 R 8 R 9 and R 10 Independently hydrogen, or substituted or unsubstituted alkyl groups each having 1 to 12 carbon atoms (or each having 1 to 6 carbon atoms), wherein the substituted or unsubstituted alkyl groups and optional substituents may have the same characteristics as described above for R. 1 and R 2 The same definitions mentioned above.

[0109] Optionally, R 4 and R 6 One of them can be connected together to form a ring structure, or R can be chosen arbitrarily. 5 and R 7They can be linked together to form a ring structure. Each of these ring structures can be optionally substituented with one or more substituents, for example, as mentioned above for R. 1 and R 2 Those mentioned above are replaced. Alternatively, R 4 and R 5 One of or R 4 and R 5 Both can be related to R respectively. 6 or R 7 connect.

[0110] Based on the total coverage (solid) of the infrared radiation sensitive image recording layer, the acid-sensitive color-changing compound (alone or a mixture of two or more thereof) of formula (I) is generally present in the infrared radiation sensitive image recording layer in an amount of at least 0.5% by weight or at least 1% by weight and at most 10% by weight or at most 15% by weight.

[0111] Some useful (3) acid-sensitive color-changing compounds can be represented by the following formula (II):

[0112]

[0113] Where R 1 To R 7 It has the same definition or meaning as equation (I).

[0114] In addition, some useful compounds within the scope of formula (I) include, but are not limited to, 3,3-bis-(4-dialkylamino-2-methoxyphenyl)-4,7-diazaphthalide; 3,3-bis-(4-dialkylamino-2-ethoxyphenyl)-4,7-diazaphthalide; 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindole-3-yl)-4,7-diazaphthalide; 3-(2-methoxy-4-di-hexylaminophenyl)-3-(1-n-octyl-2-methylindole-3-yl)-4,7-diazaphthalide; and 3-(1-n-octyl-2-methylindole-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-4,7-diazaphthalide.

[0115] Other useful compounds within the scope of formula (I) are as follows:

[0116]

[0117]

[0118]

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125]

[0126]

[0127] The infrared radiation-sensitive image recording layer according to the invention shall also comprise component (4) an infrared absorbing material (one or a mixture of two or more thereof). The infrared absorbing material (4) provides the desired infrared radiation sensitivity or converts radiation into heat, or both. Useful infrared absorbing materials (4) may be pigments or infrared radiation (including near-IR) absorbing dyes. Suitable IR absorbing dyes are, for example, those described in U.S. Patents 5,208,135 (Patel et al.), 6,153,356 (Urano et al.), 6,309,792 (Hauck et al.), 6,569,603 (Furukawa), 6,797,449 (Nakamura et al.), 7,018,775 (Tao), 7,368,215 (Munnelly et al.), 8,632,941 (Balbinot et al.), and U.S. Patent Application Publication 2007 / 056457 (Iwai et al.). In some embodiments of infrared radiation-sensitive image recording layers, it is desirable that at least one (4) infrared absorbing material in the infrared radiation-sensitive image recording layer is an cyanine dye comprising a suitable cationic cyanine chromophore and a tetraarylborate anion, such as a tetraphenylborate anion. Examples of such cyanine dyes include those described in U.S. Patent Application Publication 2011 / 003123 (Simpson et al.).

[0128] In addition to low molecular weight IR absorbing dyes, IR dye chromophores bound to polymers can also be used. Furthermore, IR dye cationic dyes can also be used, i.e., the IR absorbing portion of a dye salt that interacts ionicly with polymers containing carboxyl, sulfonyl, dioxophosphoric, or phosphonoyl groups in its side chain.

[0129] Based on the total dry cover (solid) of the infrared radiation sensitive image recording layer, the total amount of component (4) infrared absorbing material is at least 0.5% by weight or at least 1% by weight, and at most 15% by weight or at most 30% by weight.

[0130] While component (3) acid-sensitive color-changing compounds can provide strong print output images suitable for reading by cameras used in printing press automation systems such as the KBDriveTronic late Ident recognition system, it is generally desirable to include one or more component (5) color-changing compounds to obtain stable and strong visual print output images that are readable by the human eye. Useful (5) color-changing compounds of this type are described in co-pending provisional applications, U.S. Serial No. 63 / 169,278 and U.S. Serial No. 63 / 169,279, filed April 1, 2021. These (5) color-changing compounds are particularly useful when the (1) radical initiator composition contains a borate compound.

[0131] Therefore, the particularly useful (5) color-changing compounds are those represented by formula (III) or formula (IV):

[0132]

[0133] in:

[0134] Arl', Ar2', and Ar3' independently represent the atoms required to complete a substituted or unsubstituted aromatic ring (e.g., substituted or unsubstituted benzene and naphthalene rings) or a substituted or unsubstituted heteroaromatic ring (e.g., pyridine and pyrazine rings);

[0135] Y represents an oxygen atom, a sulfur atom, or a substance derived from >C(R). 4’ R 5’ ) represents a dialkylmethylene, wherein R 4’ and R 5’ Each is independently a substituted or unsubstituted alkyl group (including both straight-chain and branched alkyl groups) having 1 to 12 carbon atoms, each having 1 to 4 carbon atoms (the alkyl group may be a straight-chain or branched alkyl group);

[0136] R 1’ and R 2’ Alkyl groups are independently substituted or unsubstituted, for example, each having 1 to 12 carbon atoms, and may be straight-chain or branched alkyl groups;

[0137] R” is hydrogen, a substituted or unsubstituted alkyl group (e.g., having 1 to 12 carbon atoms, including both straight-chain and branched alkyl groups), a substituted or unsubstituted aryl group (e.g., a substituted or unsubstituted phenyl or naphthyl group), or a substituted or unsubstituted heteroaryl group (e.g., a substituted or unsubstituted pyridyl, pyrazinyl, pyrimidinyl, pyrrolithyl, furanyl, or phenylthioyl group).

[0138] X represents a single bond or is selected from -S-, -O-, and >N(R). 6’ The divalent linking group of ) wherein R 6′It is hydrogen, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms (including both straight-chain and branched alkyl groups), a substituted or unsubstituted aryl group (e.g., a substituted or unsubstituted phenyl or naphthyl group), a substituted or unsubstituted heteroaryl group (e.g., a substituted or unsubstituted pyridyl, pyrazinyl, pyrimidinyl, pyrrolithyl, furanyl or phenylthioyl group), or L;

[0139] L represents -C(=O)-OR 7’ Group, -SO2-R 3’ Group or -SO2NR 8’ R 9’ Group, wherein R 7’ This indicates a substituted or unsubstituted alkyl group (including both straight-chain and branched alkyl groups) having 1 to 12 carbon atoms, and having a -C (=O)OR... 7’ The remaining portion of the group is connected to a secondary or tertiary carbon; and R 3’ R 8’ and R 9’ Independently representing substituted or unsubstituted alkyl groups (including both straight-chain and branched alkyl groups), substituted or unsubstituted aryl groups (e.g., substituted or unsubstituted phenyl or naphthyl), or substituted or unsubstituted heteroaryl groups (e.g., substituted or unsubstituted pyridyl, pyrazinyl, pyrimidinyl, pyrrolithyl, furanyl, or phenylthioyl) each having 1 to 12 carbon atoms; wherein R 7’ It is a substituted or unsubstituted alkyl group (including both straight-chain and branched alkyl groups) having 1 to 12 carbon atoms, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group;

[0140] A 1 and A 2 Independently representing substituted or unsubstituted alkyl groups (including both straight-chain and branched alkyl groups) each having 1 to 12 carbon atoms, or together representing the two or three carbon atoms required to form a substituted or unsubstituted 5- or 6-membered non-aromatic carbon ring (e.g., a substituted or unsubstituted cyclopentyl or cyclohexyl ring); and

[0141] Za represents one or more counterions to balance the charge in the remainder of the color-changing compound according to formula (III) or (IV).

[0142] When the remainder of the color-changing compound according to formula (III) or (IV) (5) carries a positive charge, tetraarylborates such as tetraphenylborate and triarylalkylborates such as triphenyl-n-butylborate can be used as counterions of Za.

[0143] Of the compounds represented by formula (III), the compound represented by formula (V) is useful.

[0144]

[0145]

[0146] Among them, Ar1', Ar 2’ Ar 3’ R 1’ R 2’ R 3’ R, Y and Za are as defined above.

[0147] The color-changing compounds represented by formulas (III) and (IV) (5) can produce a color change in the presence of the borate compound represented by formula (VI):

[0148] [B(R 10’ R 11’ R 12’ R 13’ ) - ] n M n+

[0149] Formula (VI)

[0150] Where R 10’ R 11’ R 12’ and R 13’ Independently, it is a substituted or unsubstituted alkyl group (each having 1 to 12 carbon atoms, including both straight-chain and branched alkyl groups) or a substituted or unsubstituted aryl group (e.g., a substituted or unsubstituted phenyl or naphthyl group), and R 10’ R 11’ R 12’ and R 13’ At least three of them are the same or different substituted or unsubstituted aryl groups (e.g., substituted or unsubstituted phenyl groups); M n+ It is an n-valent cation, where n is a positive integer. Among the useful borate compounds represented by formula (VI), tetraphenylborate is particularly useful. The borate anion of the borate compound can be incorporated as part of the free radical initiator composition (1) as described above, or as a counterion into compounds represented by any one of formulas (I), (II), (III), (IV) and (V).

[0151] Based on the total coverage (solid) of the infrared radiation sensitive image recording layer, (5) the color-changing compound (alone or a mixture of two or more thereof) may generally be present in the infrared radiation sensitive image recording layer in an amount of at least 0.5% by weight or at least 1% by weight and at most 10% by weight or at most 15% by weight.

[0152] The optional but desirable component of the infrared radiation-sensitive image recording layer is component (6), a non-radical polymer material (or polymer binder), or a mixture of two or more thereof, each of which does not have any functional groups that, if present, would enable the polymer material to undergo free radical polymerization. Thus, such component (6), a non-radical polymer material, is different from all of the components (1), (2), (3), (4), and (5) described above.

[0153] Useful component (6) Non-radical polymeric materials typically have a weight-average molecular weight (M) of at least 2,000, or at least 20,000, and at most 300,000, or at most 500,000 g / mol. w ), as determined by gel permeation chromatography (polystyrene standard).

[0154] Such component (6) non-radical polymeric materials may be selected from polymeric adhesive materials known in the art, including polymers comprising repeating units having side chains containing polyoxyethylene segments, such as those described in U.S. Patent 6,899,994 (Huang et al.). Other useful polymeric adhesives comprise two or more types of repeating units with different side chains containing polyoxyethylene segments, such as those described in, for example, WO Publication 2015-156065 (Kamiya et al.). Some such polymeric adhesives may further comprise repeating units having cyano side groups, such as those described in, for example, U.S. Patent 7,261,998 (Hayashi et al.). Such component (6) non-radical polymeric materials may also have a backbone comprising a plurality (at least two) urethane moieties and side groups containing polyoxyethylene segments.

[0155] Some useful components (6) of non-radical polymeric materials can exist in particulate form, i.e., as discrete particles (non-agglomerated particles). Such discrete particles may have an average particle size of at least 10 nm and at most 1500 nm, or typically at least 80 nm and at most 600 nm, and are generally uniformly distributed within an infrared-sensitive image recording layer. The average particle size can be determined using various known methods and nanoparticle measurement devices, including measuring particles in scanning electron microscope images and averaging a set number of measurements.

[0156] Based on the total coverage (solid) of the infrared radiation sensitive image recording layer, component (6) non-radical polymeric material may be present in an amount of at least 10% by weight, or at least 20% by weight, and at most 50% by weight, or at most 70% by weight.

[0157] Other useful components (6) Non-radical polymeric materials include water-soluble polymers, such as various grades of hydroxypropyl cellulose ethers and various grades of polyvinyl alcohol with various degrees of saponification, and water-insoluble polymers, such as linear or branched polymethyl methacrylate and other acrylic polymers, polyvinyl butyral and other polyvinyl polymers, polyurethanes, polyesters, and polyureas. Examples of hydroxypropyl cellulose include Klucel E (available from Ashland, USA), Klucel M (available from Ashland, USA), Nisso HPC-L (available from Nippon Soda Co. Ltd., Japan), and Nisso HPC-SL (Nippon Soda Co. Ltd., Japan).

[0158] The infrared radiation-sensitive image recording layer used in this invention may optionally comprise cross-linked polymer particles, for example, materials having an average particle size of at least 2 μm, or at least 4 μm, and at most 20 μm, as described, for example, in U.S. Patents 9,366,962 (Hyakawa et al.), 8,383,319 (Huang et al.), and 8,105,751 (Endo et al.). Such cross-linked polymer particles may be present only in the infrared radiation-sensitive image recording layer, only in the hydrophilic protective layer (when present) (as described below), or in both the infrared radiation-sensitive image recording layer and the hydrophilic protective layer (when present).

[0159] The infrared radiation-sensitive image recording layer may also contain one or more compounds, each of which is represented by the following structure (P):

[0160]

[0161] In structure (P):

[0162] X' is one of the divalent groups -O-, -S-, -NH- or -CH2-, and preferably, X is -S- or -NH-.

[0163] Y' is one of the trivalent groups >N- or >CH-, and preferably, it is >N-.

[0164] R1 is hydrogen or a substituted or unsubstituted alkyl group, which typically has 1 to 20 carbon atoms in its unsubstituted form. When the alkyl group is substituted, it may have one or more substituents permissible by its valence, provided that these substituents do not negatively affect the provision of a suitable, stable printed output image as defined herein.

[0165] R2 and R3 are independently halogens (fluorine, chlorine, bromine, iodine), thioalkyl (i.e., -S-alkyl, the alkyl having 1 to 20 carbon atoms), phenylthio (i.e., -S-phenyl), alkoxy (i.e., -O-alkyl, the alkyl having 1 to 20 carbon atoms), phenoxy (i.e., -O-phenyl), alkyl (having 1 to 20 carbon atoms), phenyl, thioacetyl [i.e., -C(=S)CH3], or acetyl [i.e., -C(=O)CH3]. Where chemically possible, such groups may be substituted with one or more substituents, as long as they do not negatively affect the provision of suitable, stable printed output images. Particularly useful are R2 and R3 independently chlorine, thioalkyl (having 1 or 2 carbon atoms), or acetyl.

[0166] Furthermore, in the structure (P), m and n are independently 0 or integers from 1 to 4. Typically, m and n are independently 0, 1, or 2. m and n can each be zero; m can be zero and n can be 1 or 2; or m can be 1 and n can be 1 or 2.

[0167] If desired, a mixture of two or more of these compounds represented by structure (P) may be used.

[0168] One or more compounds, each represented by a structural formula (P), may be present in an amount suitable for achieving optimal printed output images and the stability of such printed output images. For example, based on the total dry weight of the infrared radiation-sensitive image recording layer, the amount of such compounds may be at least 0.05% by weight and at most 5% by weight.

[0169] The infrared radiation-sensitive image recording layer may also contain, in conventional amounts, a variety of other optional additives, including but not limited to dispersants, wetting agents, biocides, plasticizers, surfactants for coatability or other properties, tackifiers, pH adjusters, desiccants, defoamers, developing aids, rheology modifiers, or combinations thereof, or any other additives commonly used in offset printing coating. The infrared radiation-sensitive image recording layer may also contain phosphate esters (meth)acrylates having a molecular weight typically greater than 250, as described in U.S. Patent 7,429,445 (Munnelly et al.).

[0170] In addition, the infrared radiation-sensitive image recording layer may optionally contain one or more suitable chain transfer agents, antioxidants, or stabilizers to prevent or mitigate unwanted free radical reactions.

[0171] Hydrophilic protective layer:

[0172] Although in some embodiments of the invention the infrared radiation-sensitive image recording layer is the outermost layer and no layer is disposed thereon, the precursor according to the invention can be designed to have a hydrophilic protective layer (also referred to in the art as a hydrophilic outer coating, oxygen barrier layer or top coating) directly disposed on the infrared radiation-sensitive image recording layer (with no intermediate layer between the two layers), especially if the imaging precursor is designed for off-camera development (as described below).

[0173] When present, the hydrophilic protective layer is usually the outermost layer of the precursor, and thus when multiple precursors are stacked on top of each other, the hydrophilic protective layer of one precursor can come into contact with the back side of the substrate of the precursor immediately above it, where there is no release paper.

[0174] Based on the total dry weight of the hydrophilic protective layer, such a hydrophilic protective layer may contain one or more film-forming water-soluble polymeric binders in an amount of at least 60% by weight and at most 100% by weight. Such film-forming water-soluble (or hydrophilic) polymeric binders may contain modified or unmodified poly(vinyl alcohol) having a saponification degree of at least 30%, or at least 75%, or at least 90%, and at most 99.9%.

[0175] Furthermore, one or more acid-modified poly(vinyl alcohol) can be used as a film-forming water-soluble (or hydrophilic) polymer adhesive in hydrophilic protective layers. For example, at least one poly(vinyl alcohol) can be modified with an acid group selected from carboxylic acid, sulfonic acid, sulfate ester, phosphonic acid, and phosphate ester groups. Examples of useful modified poly(vinyl alcohol) materials include, but are not limited to, sulfonic acid-modified poly(vinyl alcohol), carboxylic acid-modified poly(vinyl alcohol), quaternary ammonium salt-modified poly(vinyl alcohol), glycol-modified poly(vinyl alcohol), or combinations thereof.

[0176] The optional hydrophilic outer coating may also contain cross-linked polymer particles having an average particle size of at least 2 μm and as described above.

[0177] When present, the hydrophilic protective layer is provided as a hydrophilic protective layer formulation and dried to provide at least 0.1 g / m³. 2 And at most but less than 4g / m 2 A dry coating coverage, or typically at least 0.15 g / m². 2 And at most 2.5g / m 2 Dry coating coverage. In some embodiments, the dry coating coverage is as low as 0.1 g / m³. 2 And at most 1.5g / m 2 or at least 0.1 g / m 2 And at most 0.9g / m 2 This is to make the hydrophilic protective layer relatively thin, so that it can be easily removed during off-machine development or during machine development.

[0178] Preparation of lithographic printing plate precursor:

[0179] The lithographic printing plate precursor according to the invention can be provided in the following manner. Using any suitable equipment and process, such as scraping, gravure coating, die coating, slot coating, bar coating, wire rod coating, roller coating, or extrusion hopper coating, an infrared radiation-sensitive image recording layer formulation comprising the aforementioned necessary components (1), (2), (3), (4), and (5) dissolved in a suitable solvent or solvent mixture, and any optional additives, is applied to a hydrophilic surface of a suitable aluminum-containing substrate, typically in the form of a continuous mesh as described above. Such a formulation can also be applied by spraying onto a suitable substrate. Typically, once the infrared radiation-sensitive image recording layer formulation has been applied with a suitable wet overlay, it is dried in a suitable manner known in the art to provide the desired dry overlay as described below, thereby providing an infrared radiation-sensitive continuous mesh or infrared radiation-sensitive continuous article, and then cut into rectangular sheets of appropriate size to form a lithographic printing plate precursor suitable for manufacturing a lithographic printing plate for use in lithographic printing. The components and additives of an infrared radiation-sensitive image recording layer can be designed to make the layer easily removed on-machine using one or a combination of lithographic printing inks and dampening solutions during imaging.

[0180] As described above, prior to applying the infrared radiation-sensitive image recording layer formulation, the substrate (i.e., continuous roll or mesh) can be electrochemically ground and anodized to provide a suitable hydrophilic anodic (alumina) layer on the outer surface of the aluminum-containing carrier, and the anodized surface can be post-treated with a hydrophilic polymer solution as described above. The conditions and results of these operations are well known in the art as described above.

[0181] The manufacturing process typically involves mixing various components required for the infrared radiation-sensitive image recording layer [e.g., methyl ethyl ketone (2-butanone), methanol, ethanol, 1-methoxy-2-propanol, 2-methoxypropanol, isopropanol, acetone, γ-butyrolactone, n-propanol, tetrahydrofuran, and other solvents readily known in the art and mixtures thereof] in a suitable organic solvent or mixture thereof, with or without anhydrous conditions, applying the resulting infrared radiation-sensitive image recording layer formulation to a continuous substrate mesh, and removing the solvent by evaporation under suitable drying conditions.

[0182] After proper drying, the dry coverage of the infrared radiation-sensitive image recording layer on the substrate can be at least 0.1 g / m². 2 or at least 0.4g / m 2 And at most 2g / m 2 or at most 4g / m2 However, if necessary, other amounts of dry cover can be used to provide the required dry cover.

[0183] As described above, in some embodiments, a suitable water-based hydrophilic protective layer formulation (as described above) can be applied to a dried infrared radiation-sensitive image recording layer using known coating and drying conditions, equipment, and processes.

[0184] Under actual manufacturing conditions, the result of these coating operations is a continuous radiation-sensitive mesh (or roll) of infrared radiation-sensitive lithographic printing plate precursor material, which has only an infrared radiation-sensitive image recording layer or both an infrared radiation-sensitive image recording layer and a hydrophilic protective layer as the outermost layer. Such a continuous radiation-sensitive mesh can be cut or diced into precursors of appropriately sized dimensions for use.

[0185] Imaging (exposure) conditions

[0186] During use, the infrared radiation-sensitive lithographic printing plate precursor of the present invention can be exposed to a suitable infrared radiation source, which depends on an infrared radiation absorber present in the infrared radiation-sensitive image recording layer. In some embodiments, the lithographic printing plate precursor can be imaged with one or more lasers that emit infrared radiation, said lasers emitting significant infrared radiation (including near-IR radiation) in the range of at least 750 nm and at most 1400 nm, or at least 800 nm and at most 1250 nm, to create exposed and unexposed areas in the infrared radiation-sensitive image recording layer. Such infrared radiation-emitting lasers can be used for this type of imaging in response to digital information provided by a computing device or other digital information source. Laser imaging can be digitally controlled in a manner known in the art.

[0187] Therefore, imaging can be performed using imaging or exposure to infrared radiation from an infrared radiation-generating laser (or an array of such lasers). If desired, imaging can also be performed simultaneously using imaging radiation at multiple infrared (or near-IR) wavelengths. The laser used for exposing the precursor is typically a diode laser due to the reliability and low maintenance of diode laser systems; however, other lasers, such as gas lasers or solid-state lasers, can also be used. The combinations of power, intensity, and exposure time for infrared radiation imaging will be readily apparent to those skilled in the art.

[0188] Infrared imaging equipment can be configured as a flat-panel recorder or a drum recorder, wherein an infrared radiation-sensitive lithographic printing plate precursor is mounted on the inner or outer cylindrical surface of the drum. A useful example of an imaging device is a laser diode containing radiation emitted at a wavelength of 830 nm. Models of Trendsetter plate setters (Eastman Kodak Company) and NEC AMZISetter X series (NEC Corporation, Japan) are available. Other suitable infrared imaging equipment includes Screen PlateRite 4300 or 8600 series plate setters (available from Screen USA, Chicago, IL) or thermal CTP plate setters from Panasonic Corporation (Japan), which operate at a wavelength of 810 nm.

[0189] If the infrared radiation-sensitive image recording layer is sensitive to the presence of ozone, then means for reducing or removing ozone from the environment in which laser imaging is performed may be desirable. Useful means and systems for achieving this are described, for example, in U.S. Patent Application Publication 2019 / 0022995 (Igarashi et al.).

[0190] Depending on the sensitivity of the infrared radiation-sensitive image recording layer, the imaging energy intensity can be at least 30 mJ / cm² when using an infrared radiation imaging source. 2 And at most 500mJ / cm 2 And typically at least 50 mJ / cm 2 And at most 300mJ / cm 2 To achieve high productivity during the plate-making process, the infrared radiation energy intensity is typically at or below 150 mJ / cm². 2 or below 120 mJ / cm 2 or even below 90 mJ / cm 2 .

[0191] Washing (developing) and printing

[0192] Following the image exposure as described above, the infrared-sensitive lithographic printing plate precursor, having exposed infrared radiation areas and non-exposed infrared radiation areas in the infrared radiation-sensitive image recording layer, can be rinsed off-machine or in-machine to remove the non-exposed infrared radiation areas (and any hydrophilic protective layer on such areas). After this rinsing, and during lithography, the exposed hydrophilic substrate surface repels ink, while the remaining exposed infrared radiation areas accept lithographic printing ink.

[0193] Off-machine development and printing:

[0194] Off-site rinsing can be performed using any suitable developer by applying the same or different rinsing solutions (developers) in one or more consecutive applications (treatment or development steps). Such one or more consecutive rinsing processes can be carried out long enough to remove the infrared-exposed areas of the infrared-sensitive image recording layer, thereby exposing the outermost hydrophilic surface of the substrate, but not long enough to remove a significant amount of infrared-exposed areas that have already hardened in the same layer.

[0195] Prior to such off-machine washing, the exposed precursor can be subjected to a "preheating" process to further harden the infrared-exposed areas in the infrared-sensitive image recording layer. Such optional preheating can be performed using any known methods and equipment, typically at a temperature of at least 60°C and at most 180°C.

[0196] Following, or instead of, this optional preheating, the exposed precursor may be washed (rinsed) to remove any present hydrophilic outer coating. Such optional washing (or rinsing) may be performed using any suitable aqueous solution (e.g., water or an aqueous solution of a surfactant) at a suitable temperature and for a suitable time, as will be apparent to those skilled in the art.

[0197] Useful developers can be ordinary water or formulated aqueous solutions. Formulated developers may contain one or more components selected from surfactants, organic solvents, basic reagents, and surface protectants. For example, useful organic solvents include reaction products of phenol with ethylene oxide and propylene oxide [e.g., ethylene glycol phenyl ether (phenoxyethanol)], benzyl alcohol, esters of ethylene glycol and propylene glycol with acids having six or fewer carbon atoms, and ethers of ethylene glycol, diethylene glycol, and propylene glycol with alkyl groups having six or fewer carbon atoms, such as 2-ethylethanol and 2-butoxyethanol.

[0198] In some cases, aqueous rinsing solutions can be used off-machine to achieve both imaging precursor development by removing infrared radiation-unexposed areas and providing a protective layer or coating across the entire imaging and developing (rinsing) precursor printing surface. In this embodiment, the aqueous solution behaves somewhat like an adhesive, protecting (or “coating”) the offset image on the lithographic printing plate from contamination or damage, such as from oxidation, fingerprints, dust, or scratches.

[0199] Following the off-machine rinsing and optional drying, the resulting lithographic printing plate can be mounted on the printing press without any contact with other solutions or liquids. Optionally, the lithographic printing plate may be further baked with or without blanket or flood exposure to UV or visible light radiation.

[0200] Printing can be performed by applying lithographic inks and dampening solutions to the printing surface of a lithographic printing plate in a suitable manner. The dampening solution is absorbed by the hydrophilic surface of the substrate exposed through exposure and rinsing steps, and the lithographic inks are absorbed by the remaining (exposed) areas of the infrared-sensitive image recording layer. The lithographic inks are then transferred to a suitable receiving material (e.g., cloth, paper, metal, glass, or plastic) to provide the desired image on the printing plate. If desired, an intermediate "rubber blanket" roller can be used to transfer the lithographic inks from the lithographic printing plate to the receiving material (e.g., paper).

[0201] In-machine development and printing:

[0202] Alternatively, the lithographic printing plate precursor of the present invention can be machine-developed using lithographic printing inks, dampening solutions, or a combination of lithographic printing inks and dampening solutions. In such an embodiment, the infrared-sensitive lithographic printing plate precursor (imaged according to the invention) is mounted on a printing press, and printing operation begins. During the initial printing of the plate, the infrared-unexposed areas in the infrared-sensitive image recording layer are removed by a suitable dampening solution, lithographic printing ink, or a combination of both. Typical components of an aqueous dampening solution include pH buffers, desensitizers, surfactants and wetting agents, humectants, low-boiling-point solvents, biocides, antifoaming agents, and chelating agents. A representative example of a dampening solution is Varn Litho Etch 142W + Varn PAR (alcohol-substituted) (available from Varn International, Addison, IL).

[0203] In a typical printing press starting with sheet-fed printing, the dampening rollers are first engaged and dampening solution is supplied to the mounted imaging precursor to cause the exposed infrared-sensitive image recording layer to swell, at least in the unexposed areas. After several rotations, the inking rollers engage, and they supply lithographic ink to cover the entire printing surface of the lithographic plate. Typically, within 5 to 20 rotations after the inking rollers engage, a print sheet is supplied to remove the unexposed areas of the infrared-sensitive image recording layer from the lithographic plate and the material on the blanket cylinder (if present) using the formed ink-dampening emulsion.

[0204] The machine developability of lithographic precursors exposed to infrared radiation is particularly useful when the precursor contains one or more polymer binder materials (whether or not free radical polymerizable) in an infrared radiation-sensitive image recording layer, wherein at least one of the polymer binders exists as particles having an average diameter of at least 50 nm and at most 400 nm.

[0205] The present invention provides at least the following embodiments and combinations thereof, but other combinations of features as understood by those skilled in the art from the teachings of this disclosure are considered to be within the scope of the invention:

[0206] 1. A lithographic printing plate precursor, comprising:

[0207] Base, and

[0208] An infrared radiation-sensitive image recording layer disposed on the substrate, the infrared radiation-sensitive image recording layer comprising the following components (1), (2), (3), (4), and (5):

[0209] (1) A free radical initiator composition that is capable of generating free radicals upon exposure to infrared radiation and contains a borate compound;

[0210] (2) Free radical polymerizable compositions;

[0211] (3) Acid-sensitive color-changing compounds, represented by the following formula (I):

[0212]

[0213] in:

[0214] Ar 1 For substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups;

[0215] R 1 and R 2 Independently hydrogen, substituted or unsubstituted alkyl groups each having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups, or R 1 and R 2 They can be connected to form fused rings;

[0216] R 3 It is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group having 1 to 12 carbon atoms;

[0217] R 4 and R 5 Independently hydrogen, substituted or unsubstituted alkyl groups each having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups; and

[0218] R 6 and R 7 Independently hydrogen, or substituted or unsubstituted alkyl groups having 1 to 12 carbons.

[0219] Or R 4 and R 6 They can be connected together to form a ring structure, or R5 and R 7 They can be connected together to form a ring structure, or R 4 and R 5 One or both can be associated with R respectively 6 and R 7 connect;

[0220] (4) Infrared absorbing materials; and

[0221] (5) Color-changing compounds represented by formula (III) or formula (IV):

[0222]

[0223] in:

[0224] Ar1', Ar2', and Ar3' independently represent the atoms required to complete a substituted or unsubstituted aromatic ring or a heteroaromatic ring;

[0225] Y represents an oxygen atom, a sulfur atom, or a substance derived from >C(R). 4’ R 5’ ) represents a dialkylmethylene, wherein R 4’ and R 5’ Each is an alkyl group, whether substituted or unsubstituted, and each has 1 to 4 carbon atoms;

[0226] R” is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl;

[0227] R 1’ and R 2’ Independently substituted or unsubstituted alkyl groups;

[0228] X represents a single bond or is selected from -S-, -O-, and >N(R). 6’ The divalent linking group of ) wherein R 6’ It is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, or L;

[0229] L represents -C(=O)-OR 7’ Group, -SO2-R 3’ Group or -SO2NR 8’ R 9’ Group, wherein R 7’ Indicates substituted or unsubstituted alkyl groups having the following properties: -C(=O)OR 7’ The remaining portion of the group is connected to a secondary or tertiary carbon; and R 3’ R 8’ and R 9’ Independently representing a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; R7’ It is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl;

[0230] A 1 and A 2 Independently representing substituted or unsubstituted alkyl groups, or together representing the two or three carbon atoms required to form a substituted or unsubstituted 5- or 6-membered non-aromatic carbon ring; and

[0231] Za represents one or more counterions to balance the charge in the remainder of the color-changing compound according to formula (III) or (IV), and

[0232] The borate compound is represented by the following formula (VI):

[0233] [B(R 10’ R 11’ R 12’ R 13’ ) - ] n M n+

[0234] Formula (VI)

[0235] Where R 10’ R 11’ R 12’ and R 13’ Independently, it is a substituted or unsubstituted alkyl or a substituted or unsubstituted aryl group, and R 10’ R 11’ R 12’ and R 13’ At least three of them are substituted or unsubstituted aryl groups; M n+ It is an n-valent cation, and n is a positive integer.

[0236] 2. The offset printing plate precursor described in Implementation Scheme 1, wherein R 3 It is a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.

[0237] 3. The offset printing plate precursor as described in implementation scheme 1 or 2, wherein R 4 and R 5 It is independently a substituted or unsubstituted alkyl group, each having 1 to 6 carbon atoms.

[0238] 4. The lithographic printing plate precursor according to any one of embodiments 1 to 3, wherein Ar 1 It is one of the following groups:

[0239]

[0240]

[0241] Where R 3 R 4 R 5 R 6 and R 7 As specified above, and R 8 R 9 and R 10 It is hydrogen on its own, or a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms.

[0242] 5. The lithographic printing plate precursor according to any one of embodiments 1 to 4, wherein the component (3) acid-sensitive color-changing compound is represented by formula (II).

[0243]

[0244] Where R 1 To R 7 It has the same meaning as in equation (I).

[0245] 6. The lithographic printing plate precursor according to any one of embodiments 1 to 5, wherein the component (1) free radical initiator composition comprises an onium salt.

[0246] 7. The lithographic printing plate precursor according to any one of embodiments 1 to 6, wherein the component (1) free radical initiator composition comprises a diaryliodonium cation.

[0247] 8. The lithographic printing plate precursor according to any one of embodiments 1 to 7, wherein the borate compound comprises a tetraphenylborate anion.

[0248] 9. The lithographic printing plate precursor according to any one of embodiments 1 to 8, wherein the component (1) free radical initiator composition comprises a diaryliodonium cation and a tetraarylborate anion.

[0249] 10. The lithographic printing plate precursor according to any one of embodiments 1 to 9, wherein the infrared radiation sensitive image recording layer further comprises a component (6) non-radical polymer material that is different from all of the components (1), (2), (3), (4) and (5) defined above.

[0250] 11. The lithographic printing plate precursor of embodiment 10, wherein the component (6) is a non-radical polymer material present in particulate form.

[0251] 12. The offset printing plate precursor according to any one of embodiments 1 to 11, wherein after infrared radiation exposure, the infrared radiation sensitive image recording layer is in-machine developed using offset printing ink, dampening solution, or a combination of offset printing ink and dampening solution.

[0252] 13. The lithographic printing plate precursor according to any one of embodiments 1 to 12, wherein, based on the total dry coverage of the infrared radiation sensitive image recording layer, the component (3) acid-sensitive color-changing compound represented by formula (I) is present in the infrared radiation sensitive image recording layer at a dry coverage amount of at least 0.5% by weight and at most 15% by weight.

[0253] 14. The lithographic printing plate precursor according to any one of embodiments 1 to 13, wherein the infrared radiation sensitive image recording layer is the outermost layer.

[0254] 15. The lithographic printing plate precursor according to any one of embodiments 1 to 14, wherein the component (2) free radical polymerizable composition comprises at least two free radical polymerizable components.

[0255] 16. The lithographic printing plate precursor according to any one of embodiments 1 to 15, wherein the infrared radiation-sensitive image recording layer further comprises one or more compounds, each of which is represented by the following structure (P):

[0256]

[0257] In structure (P):

[0258] X' is one of the divalent groups -O-, -S-, -NH- or -CH2-;

[0259] Y' is one of the trivalent groups >N- or >CH-;

[0260] R1 is hydrogen or a substituted or unsubstituted alkyl group;

[0261] R2 and R3 are independently halogen, thioalkyl, phenylthio, alkoxy, phenoxy, alkyl, phenyl, thioacetyl, or acetyl; and

[0262] m and n are independently 0 or integers from 1 to 4.

[0263] 17. The lithographic printing plate precursor according to any one of embodiments 1 to 16, wherein the substrate comprises an aluminum-containing substrate, the aluminum-containing substrate comprising at least one alumina layer and a hydrophilic polymer coating disposed on the at least one alumina layer.

[0264] 18. The lithographic printing plate precursor according to any one of embodiments 1 to 17, wherein the substrate comprises an aluminum-containing substrate, the aluminum-containing substrate comprising at least an inner alumina layer, an outer alumina layer disposed on the inner alumina layer, and a hydrophilic polymer coating disposed on the outer alumina layer.

[0265] 19. A method for providing a lithographic printing plate, the method comprising:

[0266] A) The lithographic printing plate precursor according to any one of embodiments 1 to 18 is exposed to infrared radiation according to the image to provide infrared radiation exposed areas and infrared radiation unexposed areas in the infrared radiation sensitive image recording layer, and

[0267] B) Remove the infrared radiation-unexposed areas from the infrared radiation-sensitive image recording layer from the substrate.

[0268] 20. The method of embodiment 19, comprising removing, in-machine, infrared-non-exposed areas in the infrared-sensitive image recording layer from the substrate using lithographic printing ink, dampening solution, or a combination of lithographic printing ink and dampening solution.

[0269] 21. The method of embodiment 19 or 20, wherein the difference in reflectance between the infrared radiation exposed area and the infrared radiation unexposed area in the infrared radiation sensitive image recording layer immediately after step (A) is at least 0.02.

[0270] 22. The method according to any one of embodiments 18 to 21, wherein the concentration is at or below 120 mJ / cm 2 The infrared radiation energy is processed in step (A).

[0271] The following examples are provided to further illustrate the implementation of the invention and are not intended to limit it in any way. Unless otherwise specified, the materials used in the examples are obtained from the various commercially available sources shown, but other commercially available sources may also be available.

[0272] The aluminum-containing substrate for lithographic printing plate precursors is prepared in the following manner:

[0273] Hydro 1052 aluminum alloy strips or meshes with a thickness of 0.28 mm (available from Norsk Hydro ASA, Norway) were used as the aluminum-containing "plate" material or carrier. Both pre-etching and post-etching steps were performed under known conditions in an alkaline solution. The etched aluminum carrier was roughened (or plate-grinding) electrochemically in a hydrochloric acid solution at 23°C to obtain an arithmetic mean roughness (Ra) of 0.4 μm on the surface of the aluminum-containing carrier. Subsequently, the aluminum-containing carrier was subjected to a single anodizing treatment using phosphoric acid as the electrolyte to form a surface roughness of 1.1 g / m². 2 An alumina layer. The anodizing step is carried out as a continuous process on a typical production line used to manufacture lithographic printing plate precursors. The aluminum-containing carrier thus prepared is then coated with an aqueous solution of polyacrylic acid to produce a substrate with a density of 0.03 g / m² that can be used in this invention. 2 The dry thickness.

[0274] Then, by individually coating the infrared radiation-sensitive composition formulation having the components and amounts shown in Tables I and II below using a bar coater, an infrared radiation-sensitive image recording layer for negative lithography is formed on the aluminum-containing substrate as described, to provide 0.9 g / m² for the precursors and comparative precursors of the various inventions described below after drying at 50°C for 60 seconds. 2 The dry coating weight. The raw materials mentioned in Table I are confirmed in Table II below. For each acid-sensitive color-changing compound (ASCC) listed in Table II, the peak absorption electromagnetic wavelength (λ) is also provided. 最大 The estimated values ​​of their absorbance are provided in Table III below, as received by Techkon SpectroDens for the spectral density of the image relative to the non-image at a wavelength of 620 nm.

[0275] These materials can be obtained from commercially available sources of one or more chemicals or prepared using known synthetic methods and starting materials.

[0276] Table I

[0277] Components Quantity (grams) polymer dispersions 0.684 Hydroxypropyl methylcellulose 0.400 Monomer 1 (free radical polymerizable component) 0.333 Monomer 2 (free radical polymerizable component) 0.167 IR dye 1 (infrared radiation absorber) 0.020 Acid-sensitive color-changing compounds labeled ASCC in Table III 0.023 Color-changing compounds identified as CCC in Table III 0.020 Surfactant 1 0.045 Iodized salt 0.060 Compound P1 0.0050 1-Propanol 3.31 2-Butanone 1.80 1-Methoxy-2-propanol 2.62 δ-Butyrolactone 0.10 water 0.44

[0278] Table II

[0279]

[0280] Table II - Continued from previous page

[0281]

[0282] Table II - Continued from previous page

[0283]

[0284] Table II - Continued from previous page

[0285]

[0286] Table II - Continued from previous page

[0287]

[0288] Table II - Continued from previous page

[0289]

[0290] Table II - Continued from previous page

[0291]

[0292] The color intensity λ of the acid-sensitive color-changing compounds (i.e., the ASCC of the present invention and the comparative ASCC compounds) mentioned in Table II was measured in a methanol solution containing 1 equivalent of HCl, relative to the amount of the acid-sensitive color-changing compound. 最大 value.

[0293] Five tests were used to evaluate the printing plate precursors and comparative lithographic printing plate precursors (or the resulting lithographic printing plates) of each invention: "Developability" (DOP), "Photospeed", and "Print Output ΔOD". 青色 "Dark fading" and "camera readability". The results are summarized in Table III below.

[0294] On a commercially available Kodak Trendsetter 3244x image setter, at 15-150 mJ / cm 2 The imaging energy exposes each precursor according to the image, thus forming a lithographic printing plate precursor exposed according to the image, which has an infrared radiation exposure area and an infrared radiation non-exposure area.

[0295] Machine-developable properties (DOP):

[0296] In-machine developability was evaluated by mounting lithographic printing plate precursors, each exposed to infrared radiation according to the image, onto a MAN Roland Favorite04 printing press without separate off-machine development (rinsing). Damping solution (VarnSupreme 6038) and lithographic ink (Gans Cyan) were supplied, and lithography was performed. In-machine development was carried out during printing and evaluated by counting the number of printed sheets required to obtain a clean background. One of the following qualitative values ​​was given for each precursor based on the number of printed sheets that obtained a clean background. For this test parameter, + and 0 estimates are acceptable.

[0297] + <5 Printing Paper

[0298] 0.5-15 Printing Paper

[0299] - >15 Printing Paper

[0300] Light sensitivity:

[0301] Printing press life was evaluated by measuring the photosensitivity of a lithographic printing plate precursor exposed to various infrared radiations. The precursor was subjected to infrared radiation exposure and in-machine development as described above. Photosensitivity was measured on the printing plate on paper after 1000 print runs by determining the ink density of solid areas exposed to different infrared radiation energies. The inflection point of ink density relative to exposure energy was considered a measure of imaging speed. The following qualitative values ​​are given as results of individual experiments, where lower imaging energies are desirable. Estimates for + and 0 for this parameter are acceptable.

[0302] + Photosensitive speed < 20 mJ / cm 2

[0303] 0. Photosensitive speed = 20 to 50 mJ / cm 2

[0304] - Photosensitive speed > 50mJ / cm 2

[0305] Printed output ΔOD 青色 :

[0306] At 90mJ / cm 2 As described above, each lithographic printing plate precursor is exposed to the image to provide infrared radiation exposed areas and infrared radiation unexposed areas in the IR-sensitive image recording layer of the negative plate. For each image-exposed lithographic printing plate precursor, the color difference between the infrared radiation exposed areas and the infrared radiation unexposed areas is measured using a Techkon Spectroc Density Meter, and the Euclidean distances of the measured L*, a*, and b* chromaticity values ​​are calculated. Cyan ΔOD represents the difference in reflected light density observed through a cyan filter between the infrared radiation exposed areas and the infrared radiation unexposed areas. The visual image on a lithographic printing plate precursor with a high absolute value of cyan ΔOD is expected to be more easily read by a camera and other reading devices constructed using diode light sources emitting light at approximately 620-640 nm. The measured values ​​of each precursor are scored below.

[0307] + ΔOD 青色 >0.200

[0308] 0 0.1≤ΔOD 青色 ≤0.200

[0309] - ΔOD 青色 <0.100

[0310] Printed output ΔOD 青色 Dark fading:

[0311] Each infrared-sensitive precursor was exposed to infrared radiation as described above and stored in the dark under ambient conditions. (ΔOD) 青色As described above, an assessment was conducted, but 24 hours after imaging (ΔOD) 青色24h (This is performed relative to the initial ΔOD measured immediately after imaging.) 青色 (ΔOD 青色0h The fading of visual images is scored. The following scores are given for the measured values ​​of each precursor:

[0312] + ΔOD 青色，24 h / ΔOD 青色，0h ≥0.90

[0313] 0 0.90>ΔOD 青色 , 24h / ΔOD 青色，0h >0.80

[0314] - ΔOD 青色，24h / ΔOD 青色，0h ≤0.80

[0315] Camera readability:

[0316] As mentioned above, at 90 mJ / cm 2 Each lithographic printing plate precursor was exposed according to the image. To perform a general assessment of camera readability using the most standard equipment, the absorption spectra of the precursors in the imaging region (the area exposed by the infrared laser) and the non-imaging region (the area not exposed by the infrared laser) were recorded using a Techkon SpektroDens spectrophotometer in reflective mode. For each precursor, absorbance values ​​at 620 nm were read from the absorption spectra of the infrared-exposed and non-exposed regions, and the difference value (Δ absorbance at 620 nm) was used to score camera readability according to the following rating criteria: a score of "0" indicates acceptable camera readability, a "+" score indicates excellent camera readability, and a "-" score indicates poor camera readability.

[0317] + Absorbance at 620 nm Δ > 0.050

[0318] 0 0.050 ≥ Absorbance at 620 nm ≥ 0.030

[0319] - Absorbance at 620 nm Δ < 0.030

[0320] The results of the evaluation of the mentioned precursors are provided in Table III below.

[0321] Table III

[0322]

[0323] Table III - Continued from previous page

[0324]

[0325] Note: “comp.” in Table III is an abbreviation of the word “Comparative”.

[0326] The results shown in Table III above indicate that, given the stability of the printed output after formation and storage in the dark, the use of the acid-sensitive color-changing compounds according to (3) of the present invention (ASCC1 to ASCC5) provides better results than those of acid-sensitive color-changing compounds outside the scope of the present invention (ASCC1 to ASCC7), without compromising other printing plate or precursor parameters such as developability or photosensitivity. As indicated herein, these results are obtained in relation to R in formula (I). 3 R 4 and R 5 The substituent at the position is irrelevant. The exposed precursor of Example 2 of the present invention, wherein a methyl group is present as R in formula (I). 1 and R 2 The (3) acid-sensitive color-changing compound (ASCC2 of the present invention) exhibited slightly weaker printout formation and fading, but the printout was still much stronger than that observed in the comparative examples. Data from Example 3 of the present invention, using ASCC3 of the present invention as the (3) acid-sensitive color-changing compound, indicate that one group according to the present invention (an aryl group having an amino group at the para position and an alkoxy group at the ortho position) is sufficient to achieve the desired effect, although from a synthetic point of view, the two aryl groups according to this structure can and are easier to prepare.

[0327] The data from Comparative Example 3 also show that if the absorbance remains low at a specific wavelength, the maximum absorbance (i.e., the absorption peak) near the desired wavelength does not provide sufficient contrast.

[0328] Data from Example 1 of the present invention, compared to Comparative Example 1, demonstrate that the alkoxy group OR in formula (I) 3 The key point is that if this structural unit is missing, a decrease in absorbance and a loss of the desired contrast will occur. The data from Example 1 of the present invention relative to Comparative Example 3 demonstrate the importance of the pyrazine structure itself in Formula (I), namely, that the absence of a second nitrogen in the heteroaromatic ring will lead to a decrease in absorbance.

Claims

1. A lithographic printing plate precursor, comprising: Base, and An infrared radiation-sensitive image recording layer disposed on the substrate, the infrared radiation-sensitive image recording layer comprising the following components (1), (2), (3), (4) and (5): (1) A free radical initiator composition that is capable of generating free radicals upon exposure to infrared radiation and contains a borate compound; (2) Free radical polymerizable compositions; (3) Acid-sensitive color-changing compounds, represented by the following formula (I): in: Ar 1 For substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups; R 1 and R 2 Independently hydrogen, substituted or unsubstituted alkyl groups each having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups, or R 1 and R 2 They can be connected to form fused rings; R 3 It is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group having 1 to 12 carbon atoms; R 4 and R 5 Independently hydrogen, substituted or unsubstituted alkyl groups each having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups; and R 6 and R 7 Independently hydrogen, or substituted or unsubstituted alkyl groups having 1 to 12 carbons. Or R 4 and R 6 They can be connected together to form a ring structure, or R 5 and R 7 They can be connected together to form a ring structure, or R 4 and R 5 One or both can be associated with R respectively 6 and R 7 connect; (4) Infrared absorbing materials; and (5) Color-changing compounds represented by formula (III) or formula (IV): in: Ar1', Ar2', and Ar3' independently represent the atoms required to complete a substituted or unsubstituted aromatic ring or a heteroaromatic ring; Y represents an oxygen atom, a sulfur atom, or a substance composed of >C(R). 4’ R 5’ ) represents a dialkylmethylene, wherein R 4’ and R 5’ Each is an alkyl group, whether substituted or unsubstituted, and each has 1 to 4 carbon atoms; R” is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl; R 1’ and R 2’ Independently substituted or unsubstituted alkyl groups; X represents a single bond or is selected from -S-, -O-, and >N(R). 6’ The divalent linking group of ) wherein R 6’ It is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, or L; L represents -C(=O)-OR 7’ Group, -SO2-R 3’ Group or -SO2NR 8’ R 9’ Group, wherein R 7’ Indicates substituted or unsubstituted alkyl groups having the following properties: -C(=O)OR 7’ The remaining portion of the group is connected to a secondary or tertiary carbon; and R 3’ R 8’ and R 9’ Independently representing a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; R 7’ It is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl; A 1 and A 2 Independently representing substituted or unsubstituted alkyl groups, or together representing the two or three carbon atoms required to form a substituted or unsubstituted 5- or 6-membered non-aromatic carbon ring; and Za represents one or more counterions to balance the charge in the remainder of the color-changing compound according to formula (III) or (IV), and The borate compound is represented by the following formula (VI): [B(R 10’ R 11’ R 12’ R 13’ )-] n M n+ Formula (VI) Where R 10’ R 11’ R 12’ and R 13’ Independently, it is a substituted or unsubstituted alkyl or a substituted or unsubstituted aryl group, and R 10’ R 11’ R 12’ and R 13’ At least three of them are substituted or unsubstituted aryl groups; M n+ It is an n-valent cation, and n is a positive integer.

2. The lithographic printing plate precursor of claim 1, wherein R 3 It is a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.

3. The lithographic printing plate precursor of claim 1, wherein R 4 and R 5 It is independently a substituted or unsubstituted alkyl group, each having 1 to 6 carbon atoms.

4. The lithographic printing plate precursor of claim 1, wherein Ar 1 It is one of the following groups: Where R 3 R 4 R 5 R 6 and R 7 As specified above, and R 8 R 9 and R 10 It is hydrogen on its own, or a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms.

5. The lithographic printing plate precursor of claim 1, wherein the acid-sensitive color-changing compound of component (3) is represented by formula (II). Where R 1 To R 7 It has the same meaning as equation (I).

6. The lithographic printing plate precursor of claim 1, wherein the component (1) free radical initiator composition comprises an onium salt.

7. The lithographic printing plate precursor of claim 1, wherein the component (1) free radical initiator composition comprises a diaryliodonium cation.

8. The lithographic printing plate precursor of claim 1, wherein the borate compound comprises a tetraphenylborate anion.

9. The lithographic printing plate precursor of claim 1, wherein the infrared radiation sensitive image recording layer further comprises a component (6) of a non-radical polymer material, which is different from all of the components (1), (2), (3), and (4) defined above.

10. The lithographic printing plate precursor of claim 9, wherein the component (6) is a non-radical polymer material present in particulate form.

11. The lithographic printing plate precursor of claim 1, wherein, based on the total dry coverage of the infrared radiation sensitive image recording layer, the component (3) acid-sensitive color-changing compound represented by formula (I) is present in the infrared radiation sensitive image recording layer in a dry coverage amount of at least 0.5% by weight and at most 15% by weight.

12. The lithographic printing plate precursor of claim 1, wherein the infrared radiation sensitive image recording layer is the outermost layer.

13. The lithographic printing plate precursor of claim 1, wherein the component (2) free radical polymerizable composition comprises at least two free radical polymerizable components.

14. The lithographic printing plate precursor of claim 1, wherein the infrared radiation-sensitive image recording layer further comprises one or more compounds, each of which is represented by the following structure (P): In structure (P): X' is one of the divalent groups -O-, -S-, -NH- or -CH2-; Y' is one of the trivalent groups >N- or >CH-; R1 is hydrogen or a substituted or unsubstituted alkyl group; R2 and R3 are independently halogen, thioalkyl, phenylthio, alkoxy, phenoxy, alkyl, phenyl, thioacetyl, or acetyl; and m and n are independently 0 or integers from 1 to 4.

15. The lithographic printing plate precursor of claim 1, wherein the substrate comprises an aluminum-containing substrate, the aluminum-containing substrate comprising at least one alumina layer and a hydrophilic polymer coating disposed on the at least one alumina layer.

16. The lithographic printing plate precursor of claim 1, wherein the substrate comprises an aluminum-containing substrate, the aluminum-containing substrate comprising at least an inner alumina layer, an outer alumina layer disposed on the inner alumina layer, and a hydrophilic polymer coating disposed on the outer alumina layer.

17. A method for providing a lithographic printing plate, the method comprising: A) Exposing the lithographic printing plate precursor according to claim 1 to infrared radiation to provide infrared radiation exposure areas and infrared radiation non-exposure areas in the infrared radiation sensitive image recording layer, and B) Remove the infrared radiation-unexposed areas from the infrared radiation-sensitive image recording layer from the substrate.

18. The method of claim 17, comprising removing, in-machine, infrared-non-exposed areas in the infrared-sensitive image recording layer from the substrate using lithographic printing ink, dampening solution, or a combination of lithographic printing ink and dampening solution.

19. The method of claim 17, wherein the difference in reflectance between the infrared radiation exposed area and the infrared radiation unexposed area in the infrared radiation sensitive image recording layer immediately after step (A) is at least 0.

02.

20. The method of claim 17, wherein the concentration is above or below 120 mJ / cm³. 2 The infrared radiation energy is processed in step (A).

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