Low Viscosity High Loading Dispersions via Dielectric Solvents
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Solution Overview
Problem
Existing pigment dispersions, especially at high loading levels, face challenges with high viscosity issues in non-aqueous solvents due to chargeable groups interacting with each other, making them difficult to process and apply effectively in techniques like inkjet printing and coatings.
Innovation Solution
A dispersion comprising a particulate material with attached anionic or cationic groups and a solvent with a dielectric constant of ≤50, combined with a dispersant that forms associative structures, results in a stable and low viscosity dispersion, even at high particulate material loadings, by optimizing the interaction between the pigment and solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high loading levels of particulate material (≥10% pigment) are used to improve color development and reduce solvent usage, then the concentration of particulate material increases, but the viscosity of the dispersion increases significantly making it difficult to process
Solution Approach 1:
A dispersant is introduced as an intermediary substance between the particulate material and solvent. The dispersant adsorbs onto the particulate material surface, providing steric or electrostatic stabilization that prevents particle aggregation and reduces interparticle friction, thereby maintaining low viscosity even at high particulate loadings of ≥10%
Solution Approach 2:
The patent modifies the surface properties of particulate material through chemical or physical treatment, changing parameters such as surface charge, hydrophobicity, or functional group composition. These parameter changes improve particle-solvent compatibility and reduce particle-particle interactions, enabling high loading levels without excessive viscosity increase
2Stability of the object's composition
If dispersants are added to improve dispersibility of high surface area pigments, then the dispersibility improves, but the dispersion viscosity increases to unacceptable levels
Solution Approach 1:
The dispersant is designed with local quality differentiation - one end or functional group specifically targets and adsorbs to the particulate material surface, while the other end remains solvated in the liquid vehicle. This localized action provides stabilization exactly where needed at the particle surface without requiring high overall dispersant concentrations that would increase bulk viscosity
3Stability of the object's composition
If chargeable groups are attached to pigments to improve dispersibility in non-aqueous systems, then the dispersibility improves, but the viscosity increases due to interactions between charged groups
Solution Approach 1:
The counterion acts as an intermediary that screens the electrostatic interactions between charged pigment particles. By introducing ions of opposite charge, the system reduces direct particle-particle electrostatic attraction or repulsion, maintaining low viscosity while preserving the dispersibility benefits of ionic modification
Solution Approach 2:
The patent controls the ionization state and charge density of modified pigments by adjusting parameters such as pH, ionic strength, or counterion type. By optimizing these parameters, the system achieves adequate charge for dispersibility while preventing excessive charge interactions that would increase viscosity
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 achieves stable, low viscosity dispersions with particulate material loadings up to 30% by weight, maintaining stability and low viscosity over time, including at elevated temperatures, which is unexpected for ionically modified particles in non-aqueous systems.
Implementation Method 1
the solvent has a dielectric constant of ≤50
Data Source
AI summary
The present invention relates to dispersions comprising particulate materials and a solvent, with an optional dispersant. The solvent has a low dielectric constant, and the particulate material is present at high loading levels. The resulting dispersion has been found to be stable and have a low viscosity, even at high particulate material loadings. Various uses for these dispersions are also disclosed.