Fluorescent Ink Solubility Parameter Matching for Brightness
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Solution Overview
Problem
Current ink jet recording methods using fluorescent inks struggle to achieve high fluorescence intensity due to concentration quenching and limited permeation of fluorescent dyes into recording media, leading to insufficient image brightness.
Innovation Solution
An ink jet recording method utilizing a combination of two aqueous inks, where the first ink contains a fluorescent dye and the second ink contains a water-soluble organic solvent, with specific solubility parameter relationships to minimize dye aggregation and enhance dye penetration, thereby increasing fluorescence intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a fluorescent ink containing fluorescent dye and polyols is used, then the fluorescence intensity is increased compared to ink without polyols, but the fluorescence intensity level is still insufficient
Solution Approach 1:
The patent changes the chemical parameters of the ink by selecting specific polyol compounds (ethylene glycol, propylene glycol, butylene glycol) and controlling their content ratios. It also controls the fluorescent dye concentration within specific ranges (0.1-5.0% by mass) to optimize fluorescence intensity while preventing concentration quenching, thereby resolving the insufficiency of fluorescence intensity achieved by previous formulations.
Solution Approach 2:
The patent creates a composite ink formulation combining fluorescent dyes with specific polyol compounds (ethylene glycol, propylene glycol, butylene glycol) in optimized ratios. This composite approach enhances fluorescence intensity by leveraging the synergistic effects of the dye-polyol interactions while maintaining ink stability and preventing aggregation, thus achieving sufficient fluorescence intensity that neither component could achieve alone.
2Illumination intensity
If a fluorescent ink using resin particles containing fluorescent coloring material is used, then the fluorescence intensity is improved, but the level is still insufficient
Solution Approach 1:
The patent changes the formulation parameters by eliminating resin particles and using free fluorescent dye molecules dissolved in the polyol-containing aqueous medium. This parameter change allows better permeation of the fluorescent dye into the recording medium while maintaining sufficient fluorescence intensity, resolving the insufficiency achieved by resin particle-based formulations.
3Illumination intensity
If the fluorescent dye concentration is increased to improve image brightness, then concentration quenching occurs and fluorescence intensity decreases
Solution Approach 1:
The patent optimizes the fluorescent dye concentration parameter within the range of 0.1-5.0% by mass, preventing both too-low concentration (insufficient brightness) and too-high concentration (concentration quenching). The specific polyol additives also modify the microenvironment to delay quenching effects, allowing effective use of the optimized dye concentration range to achieve bright images without harmful quenching.
Solution Approach 2:
The polyol compounds (ethylene glycol, propylene glycol, butylene glycol) act as intermediary substances between the fluorescent dye and the aqueous medium. They modulate the dye's solubility and distribution, preventing aggregation and concentration quenching while maintaining high fluorescence intensity and image brightness, thus mediating the contradiction between concentration and quenching.
4Illumination intensity
If the fluorescent dye permeation into the recording medium is limited, then the fluorescence intensity is reduced
Solution Approach 1:
The patent changes the chemical parameters of the ink medium by incorporating specific polyol compounds that enhance the solubility and permeation capability of fluorescent dyes into the recording medium. This parameter change increases the amount of dye that can penetrate and distribute within the medium, thereby increasing fluorescence intensity without requiring excessive dye concentration that would cause quenching.
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 method significantly improves fluorescence intensity by reducing dye aggregation and increasing dye penetration into the recording medium, resulting in brighter and more vibrant images.
Implementation Method 1
the second ink containing a first water-soluble organic solvent... an area to which the first ink is applied and an area to which the second ink is applied overlap at least in part with each other
Implementation Method 2
the coloring material of the first ink containing a fluorescent dye... significantly improves fluorescence intensity
Data Source
AI summary
The method is an ink jet recording method, which uses an ink set being composed of a plurality of aqueous inks and including a combination of a first ink containing a coloring material and a second ink containing no coloring material and by which an image is recorded by applying the first ink and the second ink onto a recording medium so that an area to which the first ink is applied and an area to which the second ink is applied overlap at least in part with each other. The coloring material of the first ink contains fluorescent dye, the second ink contains a first water-soluble organic solvent, and an SP value SS of the first water-soluble organic solvent and an SP value SD of the fluorescent dye satisfy a relationship of the following formula (1):|SS−SD|≤4.0 (1).