Azo Pigment Surface Charge Control for Transparency and Low Viscosity
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Solution Overview
Problem
Existing azo pigments face issues with transparency, dispersibility, and viscosity due to increased surface area and intermolecular attractive forces during pulverization, and zeta potential measurement methods are inaccurate for assessing pigment dispersion.
Innovation Solution
Using isopropanol (IPA) as a solvent to measure zeta potential and treating pigment surfaces with a metal element, such as iron, to achieve a specific zeta potential range of -80 to -30 mV, which enhances transparency and dispersibility while reducing viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If azo pigment is pulverized to reduce particle size, then transparency is improved, but viscosity increases due to increased surface area and intermolecular attractive forces
Solution Approach 1:
A metal element (such as iron) is introduced as an intermediary substance on the pigment particle surface. This metal element acts as a mediator that reduces intermolecular attractive forces between pigment particles through electrostatic repulsion (zeta potential control), thereby reducing viscosity while maintaining the transparency benefits of fine particle size
Solution Approach 2:
The zeta potential of the pigment particles is controlled within a specific range of -80 to -30 mV by adjusting the type and amount of metal element. This parameter change in surface charge density effectively reduces particle aggregation and viscosity while preserving the transparency achieved through particle size reduction
2Stability of the object's composition
If zeta potential is adjusted by adding surfactants or additives, then dispersibility is improved, but measurement accuracy is compromised because resin and additive interfere with the measurement
Solution Approach 1:
The metal element is incorporated onto the pigment particle surface during the pigment manufacturing process itself, before the ink formulation step. This preliminary action ensures that the zeta potential is inherently controlled by the metal element rather than by subsequent addition of surfactants or additives, enabling accurate measurement and eliminating interference from formulation additives
Solution Approach 2:
The function of zeta potential control is extracted from the ink formulation components (surfactants and additives) and transferred to the pigment particle surface itself through metal element incorporation. This separation allows the pigment to maintain stable dispersibility through its own surface properties rather than relying on external additives that interfere with measurement
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 azo pigment exhibits excellent transparency, suitable dispersibility, and low viscosity, suitable for various applications including inks, paints, and colorants, with improved pigment stability and ink performance.
Implementation Method 1
Zeta potential has been used in various fields as a parameter for determining the stability of dispersion of colloidal particles, such as pigment particles, and the degree of aggregation of the colloidal particles.
Implementation Method 2
the intermolecular attractive force due to the van der Waals force is increased accordingly
Data Source
AI summary
An object that is to be achieved by the present invention is to provide an azo pigment having excellent transparency, suitable dispersibility, and a low viscosity, an ink, and the like. An azo pigment according to the present invention has a zeta potential of −80 to −30 mV in isopropanol (IPA). The content of a metal element in the azo pigment is preferably 0.05 to 2.00 parts by mass relative to 100 parts by mass of the azo pigment. The metal element is preferably an iron element. The ratio (Fe/C) of the concentration Fe (atomic %) of an iron element in the surfaces of particles of the azo pigment to the concentration C (atomic %) of a carbon element in the surfaces of the particles of the azo pigment which are determined by X-ray photoelectron spectroscopy is preferably 0.20 or less.