Azo Compound Ink for Electrowetting Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current colorants for electrowetting displays lack high solubility in lowly polar solvents and high extinction coefficients, and there is a need for colorants with excellent light fastness and reduced compound concentration and viscosity for improved display performance.
Innovation Solution
An azo compound with a specific chemical structure is used in combination with a solvent having low relative permittivity and solubility in water, along with heterocyclic, cyanovinyl, or anthraquinone compounds, to create an ink that exhibits high solubility, high extinction coefficient, and excellent light fastness, suitable for displays and optical shutters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional colorants are used in electrowetting displays, then the display can be manufactured, but the colorants lack high solubility in lowly polar solvents and have insufficient extinction coefficients
Solution Approach 1:
The patent modifies the molecular structure of azo compounds by introducing specific substituents (alkyl groups with 4-20 carbon atoms at positions R3 and R4) to change the solubility parameters while maintaining or enhancing the extinction coefficient. This structural parameter change enables high solubility in lowly polar solvents without sacrificing optical performance
Solution Approach 2:
The invention creates a composite ink formulation combining the specially structured azo compound with lowly polar solvents (having relative permittivity of 3 or less). This composite system achieves both high solubility and high extinction coefficient by optimizing the interaction between the modified colorant and the solvent medium
2Reliability
If colorants with high extinction coefficient are used, then optical density is improved, but compound concentration and ink viscosity increase
Solution Approach 1:
The modified azo compound structure with specific alkyl substituents enhances solubility in lowly polar solvents, allowing the use of lower compound concentrations to achieve the required optical density. This reduces viscosity while maintaining high extinction coefficient
Solution Approach 2:
The patent introduces specific alkyl groups (with 4-20 carbon atoms) at particular positions (R3 and R4) of the azo compound molecule to locally enhance solubility properties. This localized structural modification improves overall solubility without compromising the chromophore's extinction coefficient
3Reliability
If high compound concentration is used to achieve high optical density, then OD value is improved, but ink viscosity increases
Solution Approach 1:
By changing the solvent parameters to use lowly polar solvents with relative permittivity of 3 or less, the patent achieves high solubility of the azo compound. This allows formulation of inks with lower compound concentrations that still achieve high optical density, thereby reducing viscosity and improving ease of operation
Solution Approach 2:
The modification of azo compound structure with specific alkyl substituents changes the solubility parameters, enabling the use of lower concentrations to achieve the same optical density. This simultaneously reduces ink viscosity and improves operational characteristics
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 compound and ink combination provides excellent hue, operation characteristics, and high optical density with reduced compound concentration and viscosity, making them suitable for electrowetting and electrophoresis displays, including electronic paper applications.
Implementation Method 1
an azo compound having a specific chemical structure and to an ink which includes an azo compound and a solvent and is useful as a display material or for optical shutters
Implementation Method 2
a solvent having a relative permittivity, measured at a frequency of 1 kHz and a temperature of 22° C., of 3 or less and a solubility in water at 25° C. of 20 mg/L or less
Data Source
AI summary
The present invention relates to an ink comprising: a solvent having a relative permittivity, measured at a frequency of 1 kHz and a temperature of 22° C., of 3 or less and a solubility in water at 25° C. of 20 mg/L or less; and a specific azo compound.