Azo Pigment Dispersion Stability via Crystal Form Control
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Solution Overview
Problem
Azo pigments with specific crystal forms for improved color characteristics and storage stability have not been adequately described, and existing methods for preparing stable pigment dispersions are inefficient and lack reproducibility.
Innovation Solution
A dispersion of an azo pigment with characteristic X-ray diffraction peaks at specific angles, combined with a method involving solvent heating and grinding treatments, to achieve a stable and efficient pigment dispersion suitable for inkjet recording inks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pigment is used to achieve good fastness and chemical resistance, then the colorant shows improved stability under environmental conditions, but the pigment requires complex particle dispersion control to maintain transparency and absorption characteristics
Solution Approach 1:
The invention controls the particle size parameter of the pigment to specifically 0.5 μm or less, and optimizes the solvent composition parameters (mixing ratios of aromatic hydrocarbons, aliphatic hydrocarbons, and esters) to achieve stable dispersion with improved fastness while maintaining transparency and absorption characteristics without complex additional controls
Solution Approach 2:
The invention uses a composite solvent system comprising multiple components (aromatic hydrocarbons like toluene, aliphatic hydrocarbons like n-hexane, and esters like ethyl acetate) in specific proportions to create a dispersion medium that stabilizes the pigment particles and improves fastness properties while maintaining optical characteristics
2Illumination intensity
If the pigment particle size is reduced to enhance transparency, then the colorant shows improved transparency, but the dispersion stability and storage stability become difficult to maintain
Solution Approach 1:
The invention optimizes the particle size parameter to 0.5 μm or less while simultaneously optimizing the solvent composition parameters (specific mixing ratios of aromatic hydrocarbons, aliphatic hydrocarbons, and esters) to prevent aggregation and maintain stable dispersion, achieving both transparency and storage stability
3Reliability
If a specific crystal form of azo pigment is used to improve color characteristics and storage stability, then the pigment shows excellent hue and light resistance, but the preparation method becomes more complex requiring solvent heating and grinding treatments
Solution Approach 1:
The invention performs preliminary crystal form conversion by heating the solvent mixture with the azo pigment before filtration, ensuring the desired crystal form is established in advance, which simplifies subsequent processing and ensures consistent color characteristics and storage stability
Solution Approach 2:
The invention utilizes phase transition of the azo pigment through controlled heating and cooling of the solvent mixture to convert between different crystal forms, enabling the pigment to achieve the desired stable crystal structure that provides excellent storage stability and light 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 solution provides azo pigments with excellent color characteristics and storage stability, enabling high-efficiency preparation of stable pigment dispersions for inkjet recording inks, enhancing light resistance and reproducibility.
Implementation Method 1
having characteristic X-ray diffraction peaks at Bragg angles (2θ±0.2°) of 4.8°, 7.2° and 9.7° in a CuKα characteristic X-ray diffraction
Implementation Method 2
having characteristic X-ray diffraction peaks at Bragg angles (2θ±0.2°) of 4.8°, 7.2° and 9.7° in a CuKα characteristic X-ray diffraction
Implementation Method 3
a step of subjecting the amorphous azo pigment or the azo pigment to solvent heating treatment
Implementation Method 4
a step of subjecting the amorphous azo pigment or the azo pigment to grinding treatment
Data Source
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Figure 5~6
AI summary
An object is to provide an azo pigment having excellent color reproducibility, dispersibility and stability of a pigment dispersion and excellent hue and tinctorial strength. A pigment dispersion including an azo pigment or a tautomer thereof represented by the following Formula (1) and having characteristic X-ray diffraction peaks at Bragg angles (2θ ± 0.2°) of 4.8°, 7.2° and 9.7° in a CuKα characteristic X-ray diffraction.