Silicate-Free Lithographic Developer with pH Stabilizer
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Solution Overview
Problem
The existing developer compositions for infrared radiation-sensitive lithographic printing plate precursors become less effective over time due to the increase in dissolved coating materials, leading to reduced protection of non-exposed regions and increased development speed, which affects the stability and performance of the printing process.
Innovation Solution
A silicate-free developer composition with a pH of at least 12.5, containing an alkali metal hydroxide and a moderator, specifically a quaternary ammonium salt or phosphonium salt, that maintains the effectiveness of the coating protecting agent and ensures consistent removal of ink receptive layers without damaging non-exposed areas, even as the developer becomes seasoned with dissolved coating materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a strong coating protecting agent (quaternary ammonium salt or phosphonium salt) is used in the developer composition, then the protection of non-exposed regions is improved, but the development speed in exposed regions decreases
Solution Approach 1:
The patent changes the chemical parameters of the developer composition by introducing a moderator (polymer with carboxylic acid or sulfonic acid groups) that interacts with the coating protecting agent. This moderator modifies the effectiveness of the coating protecting agent over time, allowing strong initial protection while maintaining development speed. The pH value is specifically controlled to be 12.0-14.0, and the moderator is present at 0.1-5.0 wt% to optimize this balance.
Solution Approach 2:
The moderator acts as an intermediary substance between the coating protecting agent and the imageable layer. It mediates the interaction by gradually reducing the coating protecting agent's effectiveness through chemical interaction (carboxylic acid or sulfonic acid groups interacting with quaternary ammonium or phosphonium salts), thereby enabling both protection and development functions to coexist effectively.
2Quantity of substance
If the developer composition is used over time, then more coating materials are dissolved, but the effectiveness of the coating protecting agent decreases and development speed increases uncontrollably
Solution Approach 1:
The moderator provides continuous stabilization of the coating protecting agent throughout the developer's usage life. As coating materials dissolve over time, the moderator continuously interacts with the coating protecting agent to maintain its effectiveness, ensuring consistent protection of non-exposed regions throughout the entire processing period rather than allowing degradation.
Solution Approach 2:
The system creates a feedback mechanism where the moderator monitors and adjusts the effectiveness of the coating protecting agent in real-time during processing. The chemical interaction between the moderator and coating protecting agent automatically compensates for the dissolution of coating materials, maintaining stable protection levels without requiring external intervention.
3Stability of the object's composition
If silicates are included in the developer composition, then buffering capacity is improved, but the developer leaves residues that affect print quality
Solution Approach 1:
The patent extracts and removes silicates from the developer composition entirely, replacing them with an alternative buffering system. The moderator (polymer with carboxylic acid or sulfonic acid groups) provides the necessary buffering capacity without leaving harmful silicate residues on the printing plate, thereby eliminating the harmful factor while maintaining the beneficial buffering function.
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 ensures consistent and efficient removal of exposed regions while protecting non-exposed regions, maintaining the stability and performance of the printing process by using a moderator to stabilize the strong coating protecting agent, thus preventing premature removal of ink receptive layers in non-exposed areas.
Implementation Method 1
an alkali metal hydroxide present in an amount sufficient to provide the pH of at least 12.5
Implementation Method 2
the positive-working lithographic printing plate precursor comprises an infrared radiation absorber
Data Source
AI summary
Lithographic printing plates are formed by imagewise exposing a single-layer or dual-layer positive-working lithographic printing plate precursor. The precursor has an outermost ink receptive layer containing a phenolic resin. The exposed precursor can be processed using a silicate-free developer composition having a pH of at least 12.5. This composition also includes an alkali metal hydroxide; a coating protecting agent that is a quaternary ammonium salt or phosphonium salt, or a mixture thereof, and a moderator for the coating protecting agent that is represented by general formula (I); wherein m is at an integer of at least 1 and up to and including 10 and M represents one or more counterions sufficient to balance the negatively-charged sulfonate groups.