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EP-4735257-A1 - LITHOGRAPHIC PRINTING PLATE PRECURSOR AND METHOD OF USE

EP4735257A1EP 4735257 A1EP4735257 A1EP 4735257A1EP-4735257-A1

Abstract

A negative-working lithographic printing plate precursor has a negative-working infrared radiation-sensitive image-recording layer that has a) two or more free radically polymerizable components; b) an initiator composition capable of generating free radicals; and c) one or more infrared radiation absorbing cyanine dyes. The a) two or more free radically polymerizable components comprise a combination of a urethane (meth)acrylate and a polyester (meth)acrylate, which together, comprise 75-100 weight % of all free radically polymerizable components. The weight ratio of the urethane (meth)acrylates to the polyester (meth)acrylates is from 90:10 to and including 35:65. The urethane (meth)acrylates comprise one or more urethane linkages and at least 4 acrylate or methacrylate ester groups. Each of the one or more polyester (meth)acrylates is free of a urethane linkage and is represented following structure (I). These precursors are less sensitive to ambient ozone and can be infrared radiation imaged and developed on-press during lithographic printing.

Inventors

  • MIYAMOTO, YASUSHI

Assignees

  • Eastman Kodak Company

Dates

Publication Date
20260506
Application Date
20240613

Claims (20)

  1. CLAIMS: 1. A negative-working lithographic printing plate precursor comprising an aluminum-containing substrate, and a negative-working infrared radiation-sensitive image-recording layer disposed on the aluminum-containing substrate, the negative-working infrared radiation-sensitive image-recording layer comprising: a) two or more free radically polymerizable components; b) an initiator composition capable of generating free radicals; and c) one or more infrared radiation absorbing cyanine dyes, wherein the a) two or more free radically polymerizable components comprise one or more urethane (meth)acrylates and one or more polyester (meth)acrylates, which together, comprise at least 75 weight % and up to and including 100 weight % of all free radically polymerizable components, wherein the weight ratio of the one or more urethane (meth)acrylates to the one or more polyester (meth)acrylates is from 90:10 to and including 35:65, wherein each of the one or more urethane (meth)acrylates comprises one or more urethane linkages and at least 4 acrylate or methacrylate ester groups, and wherein each of the one or more polyester (meth)acrylates is free of a urethane linkage and is represented by the following structure (I): X-OC(=O)-L-C(=O)-O-Y (I) wherein L represents a single bond or a carbon chain, X and Y represent independently a hydrogen atom or an organic group that is represented by structure (II) below, with the proviso that X and Y cannot both be hydrogen atoms, -A(R)n (II) wherein A represents an n+1 valent organic group, R represents a hydroxy group, an acrylate ester group (CH 2 =CHC(=O)O-), or a methacrylate ester group (CH2=C(CH3)C(=O)O-), and n is an integer equal to or greater than 1 but less than 12, with the proviso that not all R groups are hydroxy groups.
  2. 2. The negative-working lithographic printing plate precursor of claim 1, wherein the one or more urethane (meth)acrylates and one or more polyester (meth)acrylates, together, comprise at least 80 weight % of all of the a) two or more free radically polymerizable components.
  3. 3. The negative-working lithographic printing plate precursor of claim 1 or 2, wherein the negative-working infrared radiation-sensitive image- recording layer is the outermost layer.
  4. 4. The negative-working lithographic printing plate precursor of any of claims 1 to 3 that is on-press developable using a lithographic printing ink, a fountain solution, or a combination of a lithographic printing ink and fountain solution.
  5. 5. The negative-working lithographic printing plate precursor of claim 3, wherein the L linkage of structure (I) is selected from a single bond, a *CH2-CH2* group, a *CH=CH* group, and either of groups Ia and Ib shown as follows: , wherein * repre ting points to the rest of structure (I).
  6. 6. The negative-working lithographic printing plate precursor of any of claims 1 to 5, wherein the negative-working infrared radiation-sensitive image-recording layer further comprises a non-radically free polymerizable polymeric binder in particulate form.
  7. 7. The negative-working lithographic printing plate precursor of any of claims 1 to 6, wherein the a) two or more free radically polymerizable components are present in an amount of at least 20 weight % and up to and including 80 weight %, based on the total solids of the negative-working infrared radiation-sensitive image-recording layer.
  8. 8. The negative-working lithographic printing plate precursor of any of claims 1 to 7, wherein the aluminum-containing substrate comprises two or more aluminum oxide layers, and a hydrophilic polymer coating that is disposed on an outermost aluminum oxide layer.
  9. 9. The negative-working lithographic printing plate precursor of any of claims 1 to 8, wherein at least one of the one or more urethane (meth)acrylates comprises at least 5 acrylate or methacrylate groups.
  10. 10. The negative-working lithographic printing plate precursor of any of claims 1 to 9, wherein at least one of the one or more urethane (meth)acrylates comprises at least 10 acrylate or methacrylate groups.
  11. 11. The negative-working lithographic printing plate precursor of any of claims 1 to 10, wherein the a) two or more free radically polymerizable components further comprise one or more additional free radically polymerizable components that are all free of a urethane linkage and all free of a structure having at least two ester groups linked together by a bond or a carbon-carbon chain, but each of the one or more additional free radically polymerizable components comprises one or more (meth)acrylate ester groups, and the one or more additional free radically polymerizable components are present in a total amount of less than 25 weight %, based on the total weight of the a) two or more free radically polymerizable components.
  12. 12. The negative-working lithographic printing plate precursor of claim 11, each of the one or more additional free radically polymerizable components comprises a glycol ether linkage [-O-M-O-], where M represents - CH 2 -CH 2 - or CH 2 -CH(CH 3 )-.
  13. 13. The negative-working lithographic printing plate precursor of any of claims 1 to 12, wherein the one or more urethane (meth)acrylates are represented by the following structure (III) L’-[NH-C(=O)-O-X’]p (III) wherein L’ represents a p-valent linking group, p is an integer of 2 or 3, and X’ is represented by the following structure (IV), -A’(R’) n’ (IV) wherein A’ represents an n’+1 valent organic group, R ’ independently represents a hydroxy group, an acrylate ester group [CH2=CHC(=O)O-], or a methacrylate ester group[(CH2=C(CH3)C(=O)O-], and n’ is an integer equal to or greater than 1 but less than 6, with the proviso that not all R’ groups are hydroxy groups.
  14. 14. The negative-working lithographic printing plate precursor of claim 13, wherein L’ is a hydrocarbon group.
  15. 15. The negative-working lithographic printing plate precursor of claim 13, wherein L’ is an aliphatic hydrocarbon group.
  16. 16. The negative-working lithographic printing plate precursor of claim 13, wherein L’ is a hexamethylene [–(CH2)6—] group.
  17. 17. The negative-working lithographic printing plate precursor of claim 13, where A’ is represented by the following structure (V). wherein * represents the
  18. 18. A negative-working lithographic printing plate precursor comprising an aluminum-containing substrate comprising two or more aluminum oxide layers, and a negative-working infrared radiation-sensitive image-recording layer disposed as the outermost layer on the aluminum-containing substrate, the negative-working infrared radiation-sensitive image-recording layer comprising: a) two or more free radically polymerizable components; b) an initiator composition capable of generating free radicals and comprising an iodonium cation and a tetraaryl borate anion; and c) one or more infrared radiation absorbing cyanine dyes, wherein the a) two or more free radically polymerizable components comprise one or more urethane (meth)acrylates and one or more polyester (meth)acrylates, which together, comprise at least 80 weight % and up to and including 100 weight % of all free radically polymerizable components, wherein the weight ratio of the one or more urethane (meth)acrylates to the one or more polyester (meth)acrylates is from 75:25 to and including 50:50, wherein each of the one or more urethane (meth)acrylates comprises one or more urethane linkages and at least 4 acrylate or methacrylate ester groups and is represented by the following structure (III): L’-[NH-C(=O)-O-X’]p (III) wherein L’ represents a p-valent linking group, p is an integer of 2 or 3, and X’ is represented by the following structure (IV): -A’(R’)n’ (IV) wherein A’ represents an n’+1 valent organic group, R ’ independently represents a hydroxy group, an acrylate ester group [CH2=CHC(=O)O-], or a methacrylate ester group[(CH2=C(CH3)C(=O)O-], and n’ is an integer equal to or greater than 1 but less than 6, with the proviso that not all R’ groups are hydroxy groups, and wherein each of the one or more polyester (meth)acrylates is free of a urethane linkage and is represented by the following structure (I): X-OC(=O)-L-C(=O)-O-Y (I) wherein L represents a single bond or is selected from a *CH 2 - CH2* group, *CH=CH* group, and either of groups Ia and Ib shown as follows: wherein * rep ting points to the rest of structure (I), and X and Y represent independently a hydrogen atom or an organic group that is represented by structure (II) below, with the proviso that X and Y cannot both be hydrogen atoms, -A(R) n (II) wherein A represents an n+1 valent organic group, R represents a hydroxy group, an acrylate ester group (CH2=CHC(=O)O-), or a methacrylate ester group (CH 2 =C(CH 3 )C(=O)O-), and n is an integer equal to or greater than 1 but less than 12, with the proviso that not all R groups are hydroxy groups.
  19. 19. A method for providing a lithographic printing plate, comprising: A) imagewise exposing the negative-working lithographic printing plate precursor according to any of claims 1 to 18 to imaging infrared radiation, to provide exposed regions and non-exposed regions in the negative-working infrared radiation-sensitive image-recording layer, and B) removing the non-exposed regions in the negative-working infrared radiation-sensitive image-recording layer from the aluminum-containing substrate.
  20. 20. The method of claim 19 comprising removing the non- exposed regions in the negative-working infrared radiation-sensitive image- recording layer from the aluminum-containing substrate on-press using a lithographic printing ink, a fountain solution, or a combination of a lithographic printing ink and a fountain solution.

Description

LITHOGRAPHIC PRINTING PLATE PRECURSOR AND METHOD OF USE FIELD OF THE INVENTION This invention relates to infrared radiation-sensitive lithographic printing plate precursors that can be imaged using infrared radiation to provide imaged lithographic printing plates. Such precursors include a critical combination of free radically polymerizable components to provide protection of infrared absorbing cyanine dyes from ambient ozone and thereby minimize loss of on-press developability and printing durability. The inventive precursors are negative-working and particularly on-press developable. This invention also relates to methods of using these precursors to provide lithographic printing plates after appropriate infrared radiation imaging and development, especially after on- press development. BACKGROUND OF THE INVENTION Imaging systems, such as computer-to-plate (CTP) imaging systems are known in the art and are used to record an image on a lithographic printing plate precursor. Such precursors comprise a substrate typically composed of aluminum that has a hydrophilic surface on which one or more radiation- sensitive imageable layers are disposed. These precursors are used to make lithographic printing plates having lithographic ink receptive regions, known as image areas, on the hydrophilic surface of the substrate. When the printing plate surface is moistened with water and a lithographic printing ink is applied, hydrophilic regions retain the water and repel the lithographic printing ink, and the lithographic ink receptive image regions accept the lithographic printing ink and repel the water. The lithographic printing ink is transferred to the surface of a material upon which the image is to be reproduced, perhaps with the use of a blanket roller. Lithographic printing plate precursors are considered either “positive-working” or “negative-working.” Positive-working lithographic printing plates precursors are designed with one or more radiation-sensitive layers such that upon imagewise exposure to suitable radiation such as infrared radiation, the exposed regions of the layers become more alkaline solution soluble and can be removed during processing to leave the non-exposed regions that accept lithographic ink for printing. In contrast, negative-working lithographic printing plate precursors are designed with a radiation-sensitive layer such that upon imagewise exposure to suitable radiation such as infrared radiation, the exposed regions of the layer are hardened and become resistant to removal during processing, while the non- exposed regions are removable during processing. In the current state of the art in the lithographic printing industry, lithographic printing plate precursors are usually imagewise exposed to imaging radiation such as infrared radiation using lasers in an imaging device commonly known as a platesetter (for CTP imaging) before additional processing (development) to remove unwanted materials from the imaged precursors. In recent years, there has been an increased desire in the lithographic printing industry for simplification in making lithographic printing plates by carrying out development on-press (“DOP”) using a lithographic printing ink or fountain solution, or both, to remove non-exposed regions of the image-recording layer. Thus, use of on-press developable lithographic printing plate precursors is being adopted more and more in the printing industry due to many benefits, including less environmental impact and savings on processing chemicals, processor floor space, and operation and maintenance costs. After laser imaging, on-press developable precursors can be taken directly to lithographic printing presses. Many of these positive-working and negative-working lithographic printing precursors used in the industry are designed to be sensitive to near- infrared or infrared radiation (typically radiation having a radiation of at least 800 nm). It has become particularly desirable to design negative-working precursors such as those that are developable on-press to contain cyanine dye compounds, particularly those containing polymethine chains, as infrared radiation-sensitive dyes. However, it has been found that many of such cyanine infrared radiation-sensitive dyes are particularly vulnerable to attack by ambient ozone, especially when such compounds are incorporated into uppermost layer(s) of the precursors. Such attack can result in the precursors losing their on-press durability. These problems can be particularly acute when the precursors are stored for a lengthy time before they are exposed, processed (developed), and used for lithographic printing. U.S. Patent Application Publication 2019/0022993 (Igarashi et al.) describes the use of specifically placed filters in or around an imaging apparatus (such as a platesetter) to remove ambient ozone and thus to reduce the impact of ozone on negative-working lithographic printing plate precursors. U.S. Patent Application Publi