Lithographic Printing Plate Precursor with Heat-Deactivating Overcoat

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Violet laser sensitive photopolymer printing plates have limited white room light stability, requiring handling under specific light conditions and compromising between photospeed and handling window in pressroom lighting.

Innovation Solution

A negative-working photopolymer printing plate precursor with an oxygen-permeable overcoat layer that deactivates under heat, allowing handling under white room light and enhancing stability by preventing unwanted polymerization in non-image areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If photopolymer printing plates are sensitized to violet light to achieve high photospeed, then imaging speed is improved, but white room light stability deteriorates

Engineering Contradiction:

ImprovephotospeedVSAvoidwhite room light stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

An overcoat layer is introduced as an intermediary between the photopolymerizable coating and the environment. This overcoat contains a heat-decomposable compound that releases oxygen upon heating, and the oxygen acts as a mediator to deactivate the photopolymerizable coating in non-image areas, preventing unwanted polymerization while allowing the underlying violet laser sensitization to maintain high photospeed.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical-chemical parameters of the overcoat layer by incorporating heat-decomposable compounds (such as carbonates, carbamates, or hydrazides) that undergo thermal decomposition to release oxygen. This parameter change enables the overcoat to transition from an oxygen-barrier state during storage to an oxygen-releasing state upon heating, thereby controlling the polymerization activity of the photopolymerizable coating.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the overcoat layer maintains high oxygen barrier properties to protect the photopolymerizable coating, then storage stability is improved, but handling under white room light becomes problematic

Engineering Contradiction:

Improvestorage stabilityVSAvoidhandling under white room light

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The overcoat layer's oxygen barrier properties are made dynamic rather than static. The overcoat maintains high oxygen barrier properties during storage but becomes oxygen-permeable after heating treatment. This dynamic change allows the same overcoat to provide both storage stability and ease of handling under white room light, depending on the thermal history of the plate.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

A heating step is performed preliminarily to decompose the heat-decomposable compounds in the overcoat, releasing oxygen that deactivates the photopolymerizable coating in non-image areas. This preliminary action of heating and oxygen release prepares the plate for safe handling under white room light conditions before the actual printing process begins.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If the photopolymerizable coating is made highly sensitive to prevent fogging, then image quality is improved, but sensitivity to ambient light increases

Engineering Contradiction:

Improveimage qualityVSAvoidsensitivity to ambient light

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of ambient light sensitivity into a beneficial feature by using heat-decomposable compounds that release oxygen upon heating. The released oxygen selectively deactivates the photopolymerizable coating in non-image areas, transforming the potential harm of high sensitivity into a mechanism that enhances image quality by preventing fogging while allowing safe handling.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 provides a high photospeed and wide handling window under white room light conditions, preventing fogging and ensuring clean non-image areas during printing.

Implementation Method 1

The top layer comprises a heat-decomposable compound capable of generating gasses which improve the white room light stability of the lithographic printing plate precursor

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 2

the gasses generated reduce the oxygen barrier properties of the top layer, and as a result, the white room light stability of the lithographic printing plate precursor is improved

Methodology Applied

Scientific EffectOxygen permeation: Permeation

Implementation Method 3

the coating—which typically includes free radically polymerisable compounds—hardens upon exposure, optionally followed by a heating step to enhance or to speed-up this process

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS11635693B2Lithographic printing plate precursor

Publication Date: 2023.04.25 ECO3 BV

AI summary

A lithographic printing plate precursor includes a photopolymerizable coating and an overcoat which is deactivated after imagewise exposure and preheating of the precursor.