Dual-Particle Inkjet White Ink for Concealing and Sedimentation Resistance
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Solution Overview
Problem
The sedimentation velocity of titanium oxide particles in white inks is high due to their large particle diameter, leading to settling issues, which compromises the concealing and scratch resistance of recorded images, and a trade-off exists between sedimentation resistance and concealing properties.
Innovation Solution
An ink composition comprising first and second particles with specific refractive indices and particle diameters, along with a resin component, is formulated to enhance sedimentation resistance, concealing property, and scratch resistance. The first particle has a refractive index of 2.10 or more and a diameter of 100 nm or less, while the second particle has a refractive index of 1.50 or less and a diameter of 120 nm or more, with the resin component present in a specific mass ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If titanium oxide with larger particle diameter is used to enhance concealing property and whiteness, then concealing rate is improved, but sedimentation velocity increases and particles settle easily
Solution Approach 1:
The invention divides the pigment system into two distinct particle types: first particles (titanium oxide, 100 nm or less) and second particles (120 nm or more). This segmentation allows each particle type to fulfill different functions - first particles provide sedimentation resistance while second particles provide concealing property, resolving the contradiction between these two requirements.
Solution Approach 2:
The invention changes the particle diameter parameter of titanium oxide to 100 nm or less, which fundamentally alters both sedimentation velocity (reducing it significantly according to Stokes equation) and optical scattering properties. This parameter change enables the first particles to resist sedimentation while still contributing to concealing property when combined with second particles.
2Illumination intensity
If titanium oxide content is increased to enhance concealing property, then whiteness and concealing rate are improved, but sedimentation velocity increases and particles settle
Solution Approach 1:
The invention segments the pigment content into two groups with different particle sizes and properties. By controlling the content ratio (first particles: resin component = 1.1 to 5.5 times by mass), the system achieves high whiteness and concealing property without excessive titanium oxide content, thereby preventing sedimentation.
Solution Approach 2:
The invention creates a composite pigment system combining first particles (titanium oxide ≤100 nm) and second particles (≥120 nm) with a resin component in specific ratios. This composite structure achieves synergistic effects where the combination provides superior concealing property and whiteness compared to using single pigment type, while maintaining sedimentation resistance.
3Stability of the object's composition
If titanium oxide with small particle diameter is used to reduce sedimentation velocity, then sedimentation resistance is improved, but light transmission increases and concealing rate decreases
Solution Approach 1:
The invention segments the particle size distribution into two ranges: first particles (≤100 nm) for sedimentation resistance and second particles (≥120 nm) for light scattering and concealing. This segmentation allows each size range to optimize its function without compromising the other.
Solution Approach 2:
The invention merges first particles and second particles in a specific mass ratio (first particles: resin component = 1.1 to 5.5 times) to achieve combined effects. The merging of these different particle types creates a synergistic system where the sum of functions exceeds individual contributions, achieving both sedimentation resistance and high concealing rate.
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 excellent concealing and scratch resistance with improved sedimentation resistance by forming a sea-island structure during drying, ensuring uniform dispersion and scattering properties.
Implementation Method 1
the first particle has a refractive index of 2.10 or more... a scattering intensity is sharply decreased, and the concealing rate of an image to be recorded is not obtained
Implementation Method 2
forming a sea-island structure during drying, ensuring uniform dispersion and scattering properties
Implementation Method 3
the sedimentation velocity V is increased in proportion to the square of a particle diameter... titanium oxide is liable to settle in the ink
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
Provided is an ink for ink jet, which is capable of recording an image excellent in concealing property and scratch resistance, and is excellent in sedimentation resistance. The ink for ink jet includes a first particle, a second particle, and a resin component. The first particle has a refractive index of 2.10 or more. The first particle has a volume-based cumulative 50% particle diameter of 100 nm or less. The second particle has a refractive index of 1.50 or less. The second particle has a volume-based cumulative 50% particle diameter of 120 nm or more. The resin component is at least one kind selected from the group consisting of: a resin particle; and a solvent-soluble resin. The resin component has a refractive index of 1.50 or more. A content (mass%) of the first particle is 1.1 times or more to 5.5 times or less in terms of a mass ratio to a content (mass%) of the resin component.