White Ink-Jet Inks Using Composite Particle Systems
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Solution Overview
Problem
Developing white ink-jet inks with high hiding power is challenging due to the instability of high refractive index particles in thermal ink-jet systems, which results in settling issues and reduced scattering intensity when particle size is optimized for stability.
Innovation Solution
A white ink-jet ink composition comprising high refractive index particles with diameters less than 50 nanometers and large low refractive index particles with diameters between 100 and 1000 nanometers, where the low refractive index particles form an emulsion in a carrier fluid, maintaining stability and maximizing hiding power by optimizing refractive index differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high refractive index particles are used to maximize hiding power, then light scattering intensity is improved, but particle settling occurs due to high density
Solution Approach 1:
The patent combines high refractive index particles (for light scattering) with low refractive index particles (for density matching and stability). This composite particle system resolves the contradiction by allowing the high refractive index particles to provide hiding power while the low refractive index particles compensate for density, preventing settling and maintaining suspension stability.
Solution Approach 2:
The patent changes the refractive index parameter of the particle system by introducing low refractive index particles alongside high refractive index particles. This parameter modification allows the overall particle composition to have reduced effective density while maintaining high light scattering capability, thus preventing settling while preserving hiding power.
2Stability of the object's composition
If particle size is reduced to prevent settling, then suspension stability is improved, but hiding power decreases due to reduced scattering intensity
Solution Approach 1:
The patent uses a composite particle system where small particles (for stability) are combined with low refractive index particles (for density matching). This allows the small particles to remain suspended without settling while the optimized refractive index composition maintains sufficient light scattering intensity for hiding power.
Solution Approach 2:
The patent modifies the refractive index parameter of the particle system to compensate for the reduced size of particles. By introducing low refractive index particles, the overall optical properties are tuned to maintain hiding power even when particle size is reduced for stability.
3Illumination intensity
If large particles are used to maximize light scattering, then hiding power is improved, but settling occurs due to high density and large size
Solution Approach 1:
The patent creates a composite particle system where large high refractive index particles (providing light scattering) are combined with low refractive index particles (providing density matching). The low refractive index particles act as a buoyancy medium, allowing the large particles to remain suspended without settling, thus maintaining both hiding power and suspension stability.
Solution Approach 2:
The low refractive index particles function as a counterweight to the high density of large particles. By introducing these lower density particles, the overall effective density of the particle system is reduced, providing a counterbalancing effect that prevents settling of the large high refractive index particles.
4Stability of the object's composition
If refractive index of particles is matched to dispersion medium, then stability is improved, but hiding power decreases due to reduced scattering
Solution Approach 1:
The patent uses a composite particle system with two distinct refractive index components. The low refractive index particles match the dispersion medium for stability, while the high refractive index particles provide light scattering. The dual-component system allows simultaneous optimization of both stability and hiding power through complementary functions.
Solution Approach 2:
The patent applies local quality by having different particle populations serve different functions: low refractive index particles handle the stability function by matching the dispersion medium, while high refractive index particles handle the hiding power function by providing light scattering. Each particle type is optimized for its specific local function within the composite system.
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 composition achieves extended shelf life and improved hiding power by maintaining particle suspension and enhancing light scattering, with the low density of large particles matching the dispersion medium, preventing settling and ensuring stable ink performance.
Implementation Method 1
The more efficiently the incident light is scattered and returned to the observer, the better the white ink is in covering underlying colors and images
Implementation Method 2
large low refractive index particles with diameters between 100 and 1000 nanometers, where the low refractive index particles form an emulsion in a carrier fluid
Implementation Method 3
At such a small particle size, settling becomes less significant even for particles with a very large density such as titania, because of the Brownian motion/diffusion
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A white ink-jet ink includes high index of refraction particles (215) having an index of refraction greater than 1.6 and a diameter of less than 100 nanometers and low index of refraction particles (220) having an index of refraction of less than 1.5 and a diameter of between 100 and 1000 nanometers.