Ink Jet Printing Method for Titanium Oxide Precipitation Control
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Solution Overview
Problem
Inkjet printing methods face challenges with the precipitation of titanium oxide in white inks, leading to instability in ink discharge and image unevenness, particularly on transparent or low-absorbency print media.
Innovation Solution
The method involves enhancing the redispersibility of titanium oxide particles by maintaining a circulation flow rate within the liquid discharge head that exceeds the precipitation velocity, ensuring uniform pigment concentration and stable discharge through a mechanism that promotes redispersion within the circulation path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If titanium oxide is used as a colorant in white ink, then whiteness and concealability are improved, but precipitation occurs leading to discharge instability and image unevenness
Solution Approach 1:
The invention changes the surface treatment parameters of titanium oxide particles by applying specific surface treatments (silane coupling agent treatment, alumina treatment, or combination treatments) with controlled treatment conditions and sequences. This modifies the surface properties to enhance redispersibility while maintaining the whitening effect, thereby resolving the contradiction between whiteness and discharge stability.
Solution Approach 2:
The invention creates composite structures on titanium oxide particles by combining multiple surface treatments (silane coupling agents with alumina, or dual silane coupling agents). These composite surface treatments provide both the whitening properties of titanium oxide and the dispersibility enhancement from multiple functional layers, resolving the contradiction between concealability and discharge stability.
2Quantity of substance
If titanium oxide particles are dispersed in white ink, then concealability is improved, but particles precipitate over time causing image unevenness
Solution Approach 1:
The invention modifies the surface parameters of titanium oxide particles through controlled surface treatments that change the surface charge, hydrophilicity, and steric hindrance properties. These parameter changes enhance the colloidal stability of the pigment suspension, allowing high pigment concentration to be maintained with improved dispersion stability and reduced precipitation.
Solution Approach 2:
The invention introduces surface treatment agents (silane coupling agents, alumina) as intermediaries between the titanium oxide particles and the ink medium. These intermediaries improve the compatibility between pigment particles and the liquid carrier, preventing aggregation and precipitation while maintaining high pigment concentration for better concealability.
3Reliability
If circulation flow rate is increased to prevent precipitation, then discharge stability is improved, but energy consumption increases
Solution Approach 1:
The invention changes the rheological parameters of the ink by modifying particle surface properties, which reduces the viscosity and improves flow characteristics. This allows the system to maintain discharge stability with lower circulation flow rates, thereby reducing energy consumption while preventing precipitation.
Solution Approach 2:
The invention performs preliminary surface treatment of titanium oxide particles to enhance their redispersibility before ink formulation. This preliminary action creates particles that resist aggregation and precipitation, reducing the need for high-energy circulation systems and lowering ongoing energy consumption while maintaining discharge stability.
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
This approach improves the discharge stability of inks containing titanium oxide, preventing precipitation and maintaining image quality by ensuring consistent ink flow and pigment distribution.
Implementation Method 1
titanium oxide has a problem of easily precipitating
Implementation Method 2
using a titanium oxide particle having high redispersibility
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
In an ink jet printing method for discharging ink from a liquid discharge head (1), the ink contains titanium oxide having a precipitation velocity of 1.0×10-11 m/s or more based on a Stokes equation in the ink, the liquid discharge head (1) comprises a discharge port (13), a pressure chamber (12), an energy-generating element for discharging the ink, an upstream flow channel for supplying a liquid to the pressure chamber (12), a downstream flow channel communicating with the pressure chamber (12), and a pump communicating with the upstream and downstream flow channels and forming a circulation path in which the ink circulates in an order of the upstream flow channel, pressure chamber (12), downstream and upstream flow channels, and a ratio of the flow rate Q of the ink to the maximum cross-sectional area S of the circulation path, Q/S [m/s], is higher than the precipitation velocity.