Hydrophilic Printing Plate Coating for Mild-pH Clean-Out

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Solution Overview

Problem

Existing lithographic printing plate precursors face challenges in achieving both excellent clean-out performance under non-aggressive processing conditions and high press durability, particularly in on-press processing without strong alkaline solutions, while maintaining shelf-life stability and minimizing toning.

Innovation Solution

A negative-working printing plate precursor is developed with a hydrophilic copolymer containing specific monomeric units and phosphor atom-containing groups, combined with an adhesion promoting compound, to enhance clean-out behavior and presslife, using a photopolymerizable layer that can be exposed at low energy densities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional photopolymer printing plate precursors use strong alkaline processing solutions, then clean-out performance is improved, but environmental friendliness and processing aggressiveness worsen

Engineering Contradiction:

Improveclean-out performanceVSAvoidenvironmental friendliness

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the chemical composition parameters of the photopolymer coating by incorporating specific functional monomers (carboxylic acid, hydroxyl, or amino groups) that enable the coating to achieve excellent clean-out performance under mild, near-neutral pH conditions, eliminating the need for strong alkaline solutions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite photopolymer system combining multiple functional components: photoinitiators, binder polymers, and functional monomers with specific chemical groups (carboxylic acid, hydroxyl, or amino groups), which work synergistically to provide both clean-out performance and environmental compatibility

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If the coating is made highly soluble for easy clean-out, then clean-out performance is improved, but press durability and image stability worsen

Engineering Contradiction:

Improveclean-out performanceVSAvoidpress durability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies different solubility characteristics to different regions of the coating: the exposed image areas maintain high stability and resistance to dissolution, while the non-exposed areas remain highly soluble for easy removal, achieving spatially differentiated properties through photoselective crosslinking

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes controlled photopolymerization to change the solubility parameter of the coating locally: exposure induces crosslinking that reduces solubility in image areas, while unexposed areas retain high solubility for clean-out, creating a sharp contrast in dissolution behavior

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If exposure energy density is increased to improve polymerization, then polymerization completeness is improved, but energy consumption and risk of over-exposure worsen

Engineering Contradiction:

Improvepolymerization completenessVSAvoidenergy consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The patent changes the energy absorption parameters of the photopolymer system by incorporating infrared-absorbing compounds that enable efficient polymerization at low exposure energies, achieving complete crosslinking without excessive energy input or risk of over-exposure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces conventional high-energy UV or visible light exposure systems with infrared exposure systems, utilizing the different energy absorption characteristics of infrared radiation to achieve polymerization at lower energy densities with improved control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The precursor achieves improved clean-out performance and press durability, reduces toning, and maintains stability under critical storage conditions, facilitating environmentally friendly on-press processing.

Implementation Method 1

Photopolymer plate precursors rely on a working-mechanism whereby the coating—which typically includes free radically polymerisable compounds—hardens upon exposure. 'Hardens' means that the coating becomes insoluble or non-dispersible in the developing solution and may be achieved through polymerization and/or crosslinking of the photosensitive coating upon exposure to light and/or heat.

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

The coating includes an infrared-absorbing compound and a photopolymerisable compound, wherein the photopolymerisable compound is polymerisable by infrared radiation.

Methodology Applied

Scientific EffectInfrared absorption: Absorption (EM radiation)

Data Source

PatentUS12517430B2Lithographic printing plate precursor

Publication Date: 2026.01.06 ECO3 BV

AI summary

A lithographic printing plate precursor is disclosed including a support and a coating comprising a photopolymerisable layer including a polymerisable compound and a photoinitiator, characterized in that the coating comprises a hydrophilic adhesion promoting copolymer including at least one monomeric unit according to Formula I and at least one monomeric unit according to Formula II; and at least one group and/or moiety including a phosphor atom.