Core-Shell Pigment Particles for CIJ Ink Stability
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Solution Overview
Problem
Current white pigmented ink jet inks, particularly for the continuous deflected ink jet (CIJ) printing technique, face issues with sedimentation of pigment particles leading to instability, clogging, and reduced printing quality due to the high density of titanium dioxide particles, which results in poor opacity and hiding power, and are not suitable for high-shear environments like CIJ printers.
Innovation Solution
A non-aqueous ink composition using core-shell or porous white pigment particles with a lower density than traditional titanium dioxide particles, specifically designed for the CIJ printing technique, comprising organic solvent-based inks with core-shell titanium dioxide particles or porous titanium dioxide particles that maintain opacity and mechanical strength to withstand high shear stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional titanium dioxide particles are used as white pigment, then high opacity and hiding power are achieved, but high density causes sedimentation and instability in ink composition
Solution Approach 1:
The patent uses core-shell pigment particles where a low-density core material (such as polymer beads, silica, or hollow structures) is combined with a thin shell of titanium dioxide. This composite structure reduces the overall particle density while maintaining the opacity and hiding power provided by the TiO2 shell, thereby preventing sedimentation and improving ink stability.
Solution Approach 2:
The patent employs porous pigment particles with controlled porosity (e.g., 30-70% void volume) to reduce particle density. The porous structure allows the particles to maintain sufficient mechanical strength and opacity while having lower density than solid TiO2 particles, thus reducing sedimentation rates and improving ink composition stability.
2Stability of the object's composition
If pigment particle density is reduced to prevent sedimentation, then stability is improved, but opacity and hiding power may deteriorate
Solution Approach 1:
The core-shell structure concentrates the titanium dioxide shell material at the particle surface where it provides maximum optical effectiveness for opacity and hiding power. The low-density core provides buoyancy while the thin TiO2 shell (even at 5-50 nm thickness) maintains sufficient light scattering and absorption properties.
Solution Approach 2:
The patent applies the high-density, high-opacity titanium dioxide material locally at the particle surface in the form of a thin shell, while the particle interior consists of low-density material. This local concentration of optical properties ensures sufficient hiding power while the overall low density prevents sedimentation.
3Stability of the object's composition
If core-shell or porous pigment particles are used to reduce density, then sedimentation is reduced, but mechanical strength to withstand high shear stresses may be compromised
Solution Approach 1:
The core-shell structure provides mechanical strength through the combination of a rigid core and a protective TiO2 shell. The core (such as crosslinked polymer beads or hollow structures) provides structural integrity to withstand shear stresses during CIJ printing, while the shell protects the core and provides optical properties.
Solution Approach 2:
The patent uses a thin TiO2 shell that is sufficiently robust to protect the low-density core during high-shear printing operations. The shell acts as a protective film that maintains particle integrity while allowing the overall particle density to remain low for sedimentation resistance.
4Strength
If conventional solid pigment particles are used, then mechanical strength is maintained, but high density leads to clogging and reduced printing quality in CIJ printers
Solution Approach 1:
The core-shell composite particles combine the mechanical strength of a rigid core with the optical properties of a TiO2 shell, while the overall low density prevents clogging in CIJ printer nozzles. The hollow core or low-density material reduces particle mass, allowing easier passage through narrow喷嘴 while maintaining structural integrity.
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 higher stability in cartridges and printers, reduced sedimentation rates, and maintains required opacity and printing quality on various substrates, including polymers and metals, with improved resistance to friction and environmental factors.
Implementation Method 1
face issues with sedimentation of pigment particles leading to instability
Implementation Method 2
porous white pigment particles, such as porous titanium dioxide particles
Implementation Method 3
maintain opacity and mechanical strength to withstand high shear stresses
Data Source
Figure 1~4
AI summary
A non-aqueous opaque ink composition for the continuous deflected ink jet ("CIJ") printing technique, liquid at room temperature, comprising: a) a solvent; b) white pigment particles, c) a binder, comprising one or more binding resin(s); d) a dispersant; wherein: - the solvent consists of one or more organic solvent compound(s); - the white pigment particles are core shell and/or porous white pigment particles, each particle having a density lower than the density of a nonporous (solid), coreless white pigment particle. Method for marking a substrate by spraying said opaque ink jet ink composition onto this substrate, and substrate provided with a marking obtained by drying and/or absorption of said ink composition.