Water-Based Ink Pigment Dispersion Stability
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Solution Overview
Problem
Water-based pigment inks for ink-jet recording often face challenges in achieving both high optical density and storage stability, with existing solutions either compromising on one or the other.
Innovation Solution
A water-based ink formulation comprising a pigment with an average particle size of 140 nm to 160 nm, a surfactant with specific HLB values, and a glycerol-to-pigment weight ratio of 1:4, which maintains a slope value of not more than 15% at 0% evaporation rate and not less than 9% at 30% evaporation rate, as measured by centrifugal transmission sedimentation, ensuring high optical density and storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the pigment concentration is increased to improve optical density, then the optical density increases, but the storage stability deteriorates due to pigment aggregation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the average particle size of the pigment to 140-160 nm and the solid content blending amount to 8-10% by weight. These specific parameter ranges optimize the balance between optical density and storage stability, preventing pigment aggregation while maintaining high optical density in the water-based ink formulation.
Solution Approach 2:
The patent uses composite materials by combining pigment particles of specific size range (140-160 nm) with a carefully formulated water-based medium containing surfactants and additives. This composite formulation ensures both high optical density and storage stability by preventing unwanted aggregation while maintaining dispersion.
2Stability of the object's composition
If the pigment particle size is reduced to improve dispersion, then the dispersion quality improves, but the optical density decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the pigment particle size to a specific range of 140-160 nm. This intermediate size range balances dispersion quality and optical density better than smaller particles, achieving both good dispersion and high optical density simultaneously.
3Stability of the object's composition
If the surfactant concentration is increased to improve storage stability, then the storage stability improves, but the optical density decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the solid content blending amount of pigment to 8-10% by weight, which indirectly controls the effective surfactant-to-pigment ratio. This optimization ensures sufficient surfactant coverage for storage stability while maintaining high optical density, avoiding the trade-off between these two parameters.
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 formulation achieves both high optical density and storage stability by optimizing pigment dispersion and aggregation properties, allowing for stable inkjet recording with improved optical performance.
Implementation Method 1
a water-based ink for ink-jet recording including: a pigment; a surfactant; and water, wherein a slope value of the water-based ink at an evaporation rate of 0% is not more than 15%/hour; and a slope value of the water-based ink at an evaporation rate of 30% is not less than 9%/hour
Implementation Method 2
the slope value of the water-based ink being measured by a centrifugal transmission sedimentation method
Implementation Method 3
the slope value of the water-based ink being measured by a centrifugal transmission sedimentation method
Data Source
Figure 1
AI summary
There is provided a water-based ink for ink-jet recording containing: a pigment; a surfactant; and water, wherein a slope value of the water-based ink at an evaporation rate of 0% is not more than 15%/hour; and a slope value of the water-based ink at an evaporation rate of 30% is not less than 9%/hour, the slope value of the water-based ink being measured by a centrifugal transmission sedimentation method.