Ink Set Using Oxidized Self-Dispersion Pigment for High Density Printing
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Solution Overview
Problem
Ink jet recording methods using water-soluble pigments face issues with water resistance, light resistance, and fixability, particularly with self-dispersion type pigments that require high concentrations of dispersants, leading to increased viscosity and stability problems.
Innovation Solution
An ink set comprising a black ink composition and a color ink composition, both using self-dispersion type pigments with hydrophilic groups on their surfaces, and including resin emulsion to enhance fixability and stability, allowing for high color developability, ejection stability, and clogging recovery properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the ink content of the coloring agent is increased to increase the print density, then the print density is improved, but the viscosity of the ink is rapidly increased
Solution Approach 1:
The patent changes the chemical structure of the pigment molecules by introducing carbonyl groups through oxidation treatment, which fundamentally alters how the pigment interacts with the aqueous medium. This structural parameter change allows for better dispersion and reduced viscosity at higher coloring agent concentrations, resolving the contradiction between print density and viscosity
Solution Approach 2:
The patent employs strong oxidants to treat the pigment and introduce carbonyl groups on the pigment surface. This oxidation process modifies the pigment's hydrophilicity and dispersibility, enabling higher pigment concentrations to be achieved without excessive viscosity increase, thus improving print density while controlling viscosity
2Stability of the object's composition
If excessive surface active agent or polymer dispersant is used to stably disperse the pigment, then the dispersion stability is improved, but print stability deteriorates due to occurrence of bubbles or deterioration of anti-foaming property
Solution Approach 1:
The patent extracts and eliminates the need for excessive surface active agents and polymer dispersants by introducing carbonyl groups directly onto the pigment surface through oxidation. This self-dispersion mechanism removes the harmful excess dispersants that cause bubbling and anti-foaming deterioration, while still achieving stable pigment dispersion
Solution Approach 2:
The oxidized pigment with carbonyl groups on its surface serves its own dispersion function without requiring external dispersants. The pigment's modified surface chemistry enables it to self-disperse in the aqueous medium, eliminating the need for excessive additives that compromise print stability
3Ease of operation
If self-dispersion type pigment is used to achieve proper viscosity and handling, then ease of operation is improved, but fixability of the image deteriorates
Solution Approach 1:
The patent creates a composite system combining oxidized pigment particles with resin fine particles. The resin component provides the necessary binding and fixation properties that were missing from the self-dispersion pigment alone, while the oxidized pigment maintains its excellent handling characteristics. This composite approach resolves the contradiction between ease of operation and fixability
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 set achieves high color developability, ejection stability, and improved fixability, reducing clogging and maintaining printing quality with reduced dispersant usage, while maintaining proper viscosity and storage stability.
Implementation Method 1
a self-dispersion type pigment having a hydrophilic group on a surface thereof
Implementation Method 2
a hydrophilic group such as a carbonyl group, a carboxyl group, a hydroxyl group, a sulfonic group, an ammonium group or the like is bonded directly or indirectly
Implementation Method 3
the addition of resin, which has a binding effect with respect to the recording medium, to an ink composition is suggested
Data Source
AI summary
An ink set including two or more kinds of ink compositions including at least a black ink composition and a color ink composition, in which the black ink composition includes a self-dispersion type pigment having a hydrophilic group on the surface thereof, the color ink composition includes a self-dispersion type pigment having a hydrophilic group on the surface thereof with a phenyl group, and all the ink compositions include resin emulsion, is used in an ink jet recording method. Provision of an ink set for ink jet recording, which is capable of realizing a good image, in addition to high color developability, high ejection stability, high clogging recovering properties, and high fixability.