Infrared Lithographic Printing Plate Precursor Layering

Solution Overview

Problem

Conventional positive-working lithographic printing plate precursors for infrared lasers face challenges with development latitude and durability, particularly in maintaining discrimination between unexposed and exposed areas under varying application conditions, leading to issues with excessive or insufficient development.

Innovation Solution

A lithographic printing plate precursor is developed with a layered structure comprising a lower and upper layer, where the lower layer includes an alkali-soluble group-containing graft copolymer and the upper layer increases solubility in aqueous alkali solution upon exposure, utilizing an infrared absorbing agent and a polyurethane resin with ethylenically unsaturated monomer-derived constitutional units, such as sulfonamide or active imide groups, to enhance development latitude and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a recording layer with high solubility in aqueous alkali solution is used to improve development latitude, then solubility in developer is improved, but chemical resistance and durability are worsened

Engineering Contradiction:

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The recording layer is divided into multiple layers: a first recording layer with high solubility in aqueous alkali solution (improving development latitude) and a second recording layer with polyurethane resin having good chemical resistance and durability. This segmentation allows each layer to perform its specific function without compromising the other, resolving the contradiction between development latitude and chemical resistance

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure combining different resin materials in the recording layer. The first recording layer uses resins with high solubility (such as polyacrylic acid or polyacrylamide derivatives) while the second recording layer uses polyurethane resin with acidic hydrogen atom-containing macromonomer units. This composite material approach enables both high development latitude and excellent chemical resistance to be achieved simultaneously

Inventive Principle:

Principle #40Composite materials

2Reliability

If polyurethane resin with acidic hydrogen atom-containing macromonomer unit is used to improve solvent resistance and durability, then durability is improved, but development latitude is worsened

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The recording layer is segmented into a first recording layer with high solubility resins for development latitude and a second recording layer with polyurethane resin for durability. This allows the polyurethane resin to provide chemical resistance without restricting the development latitude provided by the first recording layer

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the recording layer are assigned different properties: the first recording layer is designed with high solubility characteristics for optimal development response, while the second recording layer is designed with polyurethane resin for enhanced durability. Each layer performs its specific function locally, resolving the contradiction between durability and development latitude

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 provides improved development latitude and printing durability by maintaining effective discrimination between unexposed and exposed areas, reducing post-exposure degradation and ensuring stable development even after storage.

Implementation Method 1

an infrared absorbing agent, etc., which absorbs light and generates heat

Methodology Applied

Scientific EffectInfrared absorption: Absorption (EM radiation)

Implementation Method 2

the interaction between the infrared absorbing agent, etc. and the binder resin weakens due to the generated heat and dissolution in an alkali developer progresses

Methodology Applied

Scientific EffectThermal dissolution: Heating

Data Source

PatentUS9046774B2Positive-working lithographic printing plate precursor for infrared laser and process for making lithographic printing plate

Publication Date: 2015.06.02

AI summary

A positive-working lithographic printing plate precursor for infrared laser is provided that includes, layered sequentially above a support, a lower layer and an upper layer, the lower layer and/or the upper layer including an infrared absorbing agent, either the lower layer comprising an alkali-soluble group-containing graft copolymer or the upper layer comprising a sulfonamide group-, active imide group-, and/or amide group-containing graft copolymer, and the graft copolymer being a polyurethane resin having as a graft chain an ethylenically unsaturated monomer-derived constitutional unit. There is also provided a process for making a lithographic printing plate, the process including in sequence an exposure step of imagewise exposing by means of an infrared laser the positive-working lithographic printing plate precursor for infrared laser and a development step of developing using an aqueous alkali solution with a pH of 8.5 to 10.8.