Lithographic Printing Plate Overcoat Layer Interfacial Mixing

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Solution Overview

Problem

Lithographic printing plate precursors face issues with development property and dispersion stability in gum development, and on-press development, particularly concerning ink receptivity, sensitivity, and printing durability, due to interfacial mixing and residual water-soluble resins in the image-recording layer.

Innovation Solution

A lithographic printing plate precursor with an overcoat layer containing a polymer resin that has a cloud point in an aqueous solution, including specific monomer units, which inhibits interfacial mixing and enhances dispersion stability, comprising a support, an image-recording layer with a radical polymerization initiator and radical polymerizable compound, and an overcoat layer with an inorganic stratiform compound.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an overcoat layer containing water-soluble resin is used to prevent oxygen inhibition, then sensitivity and printing durability are improved, but interfacial mixing occurs between the overcoat layer and image-recording layer causing poor development property and inferior ink receptivity

Engineering Contradiction:

Improveprinting durabilityVSAvoiddevelopment property

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the overcoat layer by replacing water-soluble resin with a polymer resin having specific functional groups (carboxyl, hydroxyl, or amine groups with specific content ranges). This parameter change prevents interfacial mixing while maintaining the oxygen-blocking function, thus resolving the contradiction between printing durability and development property.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If conventional highly alkaline developer is used for development, then removal of unnecessary image-recording layer is effective, but environmental pollution from waste liquid discharge increases

Engineering Contradiction:

Improvedevelopment efficiencyVSAvoidenvironmental pollution

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the pH parameter of the development system by making the overcoat layer removable with near-neutral pH gum solution instead of highly alkaline developer. The polymer resin in the overcoat layer is designed to be soluble or dispersible in neutral pH conditions, enabling environmentally friendly development while maintaining effective removal of unnecessary image-recording layer.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If polymer resin with amino group or amido bond is used in overcoat layer, then gum development property and dispersion stability are improved, but the structure becomes more complex

Engineering Contradiction:

Improvedispersion stabilityVSAvoidpolymer structure complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent applies local quality by introducing specific functional groups (amino or amido bonds) only in the overcoat layer polymer resin, while keeping the image-recording layer composition relatively simple. This localized functional group introduction provides the necessary dispersion stability and gum development property without requiring complex structures throughout the entire printing plate system.

Inventive Principle:

Principle #3Local quality

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 solution improves gum development property, running processing property, and scratch resistance while maintaining on-press development performance, ink receptivity, and printing durability by preventing interfacial mixing and ensuring stable dispersion of the overcoat layer components.

Implementation Method 1

an overcoat layer containing a polymer resin which has a cloud point in an aqueous solution

Methodology Applied

Scientific EffectCloud point: Phase Change

Implementation Method 2

an image-recording layer with a radical polymerization initiator and radical polymerizable compound

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP2554395B1Master planographic printing plate and manufacturing method therefor

Publication Date: 2016.04.27 FUJIFILM CORP

Figure 1

AI summary

To provide a lithographic printing plate precursor which is excellent in the gum development property, running processing property and scratch resistance and a lithographic printing plate precursor which is good in all performances of the on-press development property, ink receptivity, sensitivity and printing durability, and a method of producing thereof. A lithographic printing plate precursor comprising a support, an image-recording layer containing a radical polymerization initiator and a radical polymerizable compound, and an overcoat layer containing a polymer resin which has a cloud point in an aqueous solution and includes a monomer unit containing at least any of an amino group and an amido bond, in this order.