Dual-Size Particle Ink for White Concealment and Scratch Resistance
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Solution Overview
Problem
Existing inks using titanium oxide for white images suffer from sedimentation due to high specific gravity, leading to a trade-off between concealing property and scratch resistance, and require improvements in sedimentation resistance and image quality.
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 concealing property and scratch resistance while minimizing sedimentation.
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 property is improved, but sedimentation resistance deteriorates
Solution Approach 1:
The patent divides the white pigment into two distinct particle size ranges: first particles (100 nm or less in volume-based cumulative 50% particle diameter) and second particles (120 nm or more in volume-based cumulative 50% particle diameter). This segmentation allows smaller first particles to resist sedimentation while larger second particles provide enhanced light scattering and concealing property, resolving the trade-off between concealing property and sedimentation resistance
Solution Approach 2:
The patent assigns different functional roles to particles of different sizes within the same ink system. First particles with smaller diameter are optimized for sedimentation resistance, while second particles with larger diameter are optimized for light scattering and concealing property. This local differentiation of particle qualities allows simultaneous achievement of both sedimentation resistance and high concealing property
2Illumination intensity
If titanium oxide content is increased to enhance concealing property, then concealing property is improved, but sedimentation resistance deteriorates
Solution Approach 1:
The patent segments the titanium oxide content into two functional groups with different particle diameter ranges. The first particles (≤100 nm) constitute a portion of the total pigment content and provide sedimentation resistance, while the second particles (≥120 nm) constitute another portion and provide enhanced light scattering. This segmentation allows the total titanium oxide content to be increased for better concealing property while maintaining sedimentation resistance through the presence of smaller first particles
Solution Approach 2:
The patent creates a composite pigment system comprising two different particle size ranges of titanium oxide within the same ink formulation. This composite approach combines the sedimentation-resistant properties of smaller particles with the high light-scattering properties of larger particles, enabling increased total pigment content for improved concealing property without sacrificing sedimentation stability
3Illumination intensity
If titanium oxide is used for white image recording, then concealing property is improved, but sedimentation occurs due to high specific gravity
Solution Approach 1:
The patent segments titanium oxide particles into two size categories to address the sedimentation issue caused by high specific gravity. Smaller first particles (≤100 nm) have reduced sedimentation velocity according to Stokes law, while larger second particles (≥120 nm) provide the necessary light scattering. This segmentation strategy allows effective use of titanium oxide for white image recording while mitigating sedimentation
Solution Approach 2:
The patent changes the particle diameter parameter of titanium oxide from a single size distribution to a bimodal distribution with distinct ranges. By controlling the volume-based cumulative 50% particle diameter of first particles to be 100 nm or less and second particles to be 120 nm or more, the patent optimizes both sedimentation resistance and light scattering properties, resolving the contradiction between concealing property and sedimentation resistance
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 improved concealing property and scratch resistance with reduced sedimentation by utilizing a sea-island structure in the dry film, ensuring uniform dispersion and enhanced refractive index difference.
Implementation Method 1
the first particle has a refractive index of 2.10 or more... the second particle has a refractive index of 1.50 or less... enhanced refractive index difference
Implementation Method 2
a resin component... wherein the resin component is at least one kind selected from the group consisting of: a resin particle; and a solvent-soluble resin
Data Source
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 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 to a content (mass %) of the resin component.