Crown Ether Stabilized Thermally Developable Imaging Materials
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Solution Overview
Problem
Thermally developable silver-containing materials face challenges with high silver coating weights due to variability in sensitometric properties, such as maximum density achieved with exposure (Dmax), which changes with humidity, leading to increased manufacturing costs and loss of grey scale with reduced silver usage.
Innovation Solution
Incorporating a crown ether-alkali metal complex cation and an enolate anion of an aldehyde with an electron withdrawing group in the alpha position as a co-developer compound in thermally developable imaging layers, which stabilizes imaging properties and reduces silver usage without significant changes in Dmax or grey scale with humidity variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silver coating weight is reduced to lower manufacturing costs, then manufacturing cost decreases, but imaging property stability deteriorates due to humidity variability
Solution Approach 1:
A crown ether compound is introduced as an intermediary substance that mediates between the silver ions and humidity environment. The crown ether forms complexes with alkali metal ions that would otherwise interfere with silver ion stability, thereby protecting the imaging properties from humidity variations even at reduced silver coating weights
Solution Approach 2:
The patent modifies the chemical environment by adding crown ether compounds that change the interaction parameters between silver ions and humidity. This alters the stability characteristics of the silver-containing material, enabling consistent imaging properties across different humidity conditions without requiring high silver coating weights
2Reliability
If silver coating weight is increased to maintain imaging properties, then imaging property stability improves, but manufacturing cost increases
Solution Approach 1:
The crown ether compound acts as a protective intermediary that enhances the effectiveness of each silver ion. By forming stable complexes and preventing interference from alkali metal ions, the crown ether allows reduced silver quantities to achieve the same imaging stability that would otherwise require higher silver coating weights
Solution Approach 2:
The addition of crown ether changes the chemical parameters of the system, specifically the stability constants and interaction energies between silver ions and environmental moisture. This parameter change enables achieving high reliability at lower material concentrations
3Ease of manufacture
If silver usage is reduced to lower costs, then manufacturing cost decreases, but grey scale quality deteriorates
Solution Approach 1:
The crown ether serves as a mediating agent that ensures uniform and controlled reduction of silver ions. This mediation prevents non-uniform grey scale formation that would otherwise occur with reduced silver quantities, maintaining precision in the imaging process while using less silver
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
This approach allows for reduced silver coating weights while maintaining consistent imaging properties, improving Silver Efficiency and minimizing the impact of humidity on sensitometric characteristics, thus reducing manufacturing costs and maintaining image quality.
Implementation Method 1
a co-developer compound that is a crown ether-alkali metal complex cation and an enolate anion of an aldehyde
Implementation Method 2
a reducing agent for the reducible silver ions... Upon heating, and at elevated temperatures, the reducible silver ions are reduced by the reducing agent
Data Source
AI summary
Incorporating a crown ether-alkali metal complex cation of an enolate anion of an aldehyde having at least one electron withdrawing group in the alpha (α) position, provides thermally developable materials with imaging properties that have little change with changes in humidity. Both photothermographic and thermographic materials are provided, and particularly photothermographic materials having lower silver coverage.