Ink Formulation for High Optical Density and Scratch Resistance
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Solution Overview
Problem
Inks containing self-dispersing pigments with phosphonic acid groups struggle to achieve both high image optical density and scratch resistance, often resulting in images with low scratch resistance and quality issues like streaks due to hydrophilization of the recording medium.
Innovation Solution
An ink composition combining a phosphonic acid-type self-dispersing pigment, polyurethane resin particles, and a specific surfactant represented by general formula (1) is used, which reduces surface tension and suppresses hydrophilization of the recording medium, thereby enhancing image color development and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If self-dispersing pigments with phosphonic acid groups are used to improve image optical density, then color development is enhanced, but scratch resistance deteriorates
Solution Approach 1:
The invention uses a composite ink formulation containing both self-dispersing phosphonic acid-type pigment particles and polyurethane resin particles. The pigment particles provide high optical density and color development, while the polyurethane resin particles provide scratch resistance. This composite approach allows both functions to work together without compromising either property.
2Illumination intensity
If surfactants are added to improve ink spreading, then color development is enhanced, but hydrophilization of recording medium occurs causing streaks
Solution Approach 1:
The invention carefully controls the surfactant concentration and selects specific surfactant types that reduce surface tension to optimize ink spreading and color development, while maintaining concentrations below the threshold that causes excessive hydrophilization and streak formation. This parameter optimization allows beneficial effects without triggering harmful side effects.
3Strength
If polyurethane resin particles are added to improve scratch resistance, then image durability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The invention uses pre-formed polyurethane resin particles with controlled size distributions (0.1-10 μm) that can be directly incorporated into the ink formulation. This segmentation approach simplifies the manufacturing process compared to forming resin matrices in situ, as the particles are ready-to-use building blocks that maintain their structural integrity and functional properties upon incorporation.
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 ink achieves high image color development and quality by maintaining surface tension reduction and preventing hydrophilization, resulting in improved scratch resistance and reduced streak formation.
Implementation Method 1
The surfactant is represented by general formula (1)... reduces surface tension and suppresses hydrophilization of the recording medium
Implementation Method 2
self-dispersing pigments having a phosphonic acid group bonded directly or via another atomic group to the surfaces thereof
Data Source
AI summary
An ink includes a self-dispersing pigment, polyurethane resin particles, a surfactant, and water. The self-dispersing pigment is a pigment having a phosphonic acid group bonded directly or via another atomic group to a surface thereof. The surfactant is represented by general formula (1):