Ink-Jet Pigment Particle Diameter Control for Print Quality
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Solution Overview
Problem
Current ink-jet recording technologies face challenges in achieving high optical density and clear edges for black prints and high gloss for color prints, while ensuring good ejectability from the ink-jet head, due to the use of pigment inks which are not water-soluble and have uneven particle diameter distributions.
Innovation Solution
Adjusting the average particle diameter and particle diameter distribution width of pigments in black and color inks within specific ranges (90 nm to 130 nm and 100 nm or less, respectively) to enhance ejectability, optical density, and gloss, using techniques like wet sand milling to optimize dispersion processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pigment inks are used to provide excellent storage stability, water resistance, light fastness and ozone resistance, then recorded objects have good storage stability, but ejectability from ink-jet head deteriorates because the pigment is not water soluble
Solution Approach 1:
The patent applies parameter changes by precisely controlling the average particle diameter of pigment particles within 90-130 nm for black ink and 50-100 nm for color inks, and by controlling the particle diameter distribution width (D95-D5)/Da to be 1.4 or less for black ink and 1.3 or less for color inks. These parameter optimizations enable pigment inks to achieve both good storage stability and improved ejectability from ink-jet heads.
2Ease of manufacture
If conventional techniques are used to select ink components and optimize average particle diameter, then ink formulation is simplified, but high quality text printing with high OD and clear edges cannot be achieved
Solution Approach 1:
The patent transitions from conventional simple optimization to precise parameter control by defining specific ranges for average particle diameter (Da: 90-130 nm for black, 50-100 nm for colors) and distribution width ((D95-D5)/Da ≤ 1.4 for black, ≤ 1.3 for colors). This enables high OD values and clear edges in text printing while maintaining manageable formulation complexity.
3Ease of manufacture
If conventional techniques are used for ink formulation, then development process is simplified, but high quality photo images with high gloss cannot be obtained
Solution Approach 1:
The patent applies parameter changes by controlling pigment particle diameter (Da: 50-100 nm) and distribution width ((D95-D5)/Da ≤ 1.3) in color inks. These precise parameter controls enable high gloss appearance in photo images while keeping the development process manageable through systematic optimization rather than trial-and-error.
Data Source
AI summary
A black ink for ink-jet includes a pigment wherein an average particle diameter Da of the pigment is in the range of about 90 nm to about 130 nm. In addition, (D95−D5)/Da is about 1.4 or less, where D5 is the 5% cumulative particle diameter of the pigment and D95 is the 95% cumulative particle diameter of the pigment. A color ink for ink-jet recording also includes a pigment with the value Da of about 100 nm or less and (D95−D5)/Da of about 1.3 or less.