Water-Soluble Azo Compound Ink for Ozone Fastness
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Solution Overview
Problem
Current ink jet recording methods face challenges in achieving high print density and excellent light fastness, ozone fastness, and color fading balance, particularly for hues ranging from yellow to orange to brown to red, due to discoloration caused by oxidizing gases like ozone.
Innovation Solution
A water-soluble azo compound represented by a specific formula, or its salt, is used in an ink composition that provides high print density and light fastness, with a crosslinking group for improved solubility and stability, allowing for effective ink jet recording on materials with an ink-receiving layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional water-soluble coloring matters are used in ink jet recording, then the ink composition can be prepared with good solubility and flow properties, but the recorded images exhibit poor ozone fastness and significant discoloration due to oxidizing gases
Solution Approach 1:
The patent introduces a specific azo compound with a unique molecular structure containing a 1,3,4-oxadiazol-2-one ring system that converts the harmful effect of ozone into a beneficial outcome. The compound's specific chemical structure with electron-donating groups (alkyl, alkoxy, hydroxyl, or amino groups) at designated positions creates a stable chromophore that resists oxidation. When exposed to ozone, the compound maintains its color stability due to the electron delocalization and resonance stabilization in the oxadiazolone ring, effectively converting the oxidizing environment from harmful to harmless.
Solution Approach 2:
The patent achieves improved ozone fastness by changing the chemical parameters of the coloring matter. Specifically, it uses an azo compound with the formula where R1 represents electron-donating groups (alkyl, alkoxy, hydroxyl, or amino groups) and R2 represents specific substituents. This parameter change in molecular structure—introducing the 1,3,4-oxadiazol-2-one ring system with appropriate substituents—fundamentally alters the compound's resistance to oxidation, enabling high ozone fastness while maintaining good solubility in water-soluble organic solvents.
2Manufacturing precision
If coloring matters with high print density are used, then the recorded images achieve sufficient density, but the color fading balance between various hues deteriorates upon exposure to light or oxidizing gases
Solution Approach 1:
The patent employs a composite molecular structure combining an azo group (-N=N-) with a 1,3,4-oxadiazol-2-one ring system, creating a hybrid chromophore that integrates the advantages of both structural motifs. The azo group provides high color intensity and print density, while the oxadiazolone ring with its electron-donating substituents contributes to oxidation resistance and color stability. This composite structure achieves both high print density and excellent color fading balance across yellow, magenta, and black hues.
Solution Approach 2:
The patent applies local quality by introducing electron-donating groups (alkyl, alkoxy, hydroxyl, or amino groups) at specific positions (R1 and R2) of the azo compound molecule. These localized substituents enhance the electron density in specific regions of the chromophore, creating zones of high electron delocalization that stabilize the molecule against oxidation. This local modification at strategic positions maintains high color intensity while providing uniform protection across different hues, ensuring balanced color fading resistance.
3Ease of operation
If water-soluble organic solvents are added to prevent clogging, then the ink composition achieves satisfactory flow properties and nozzle performance, but the storage stability and image fastness properties may be compromised
Solution Approach 1:
The patent uses water-soluble organic solvents as intermediaries to bridge the requirements for nozzle flow properties and storage stability. The specific azo compound serves as a mediating substance that is highly compatible with water-soluble organic solvents, maintaining excellent solubility and preventing precipitation during storage. The compound's polar oxadiazolone ring system interacts favorably with polar solvents, ensuring stable ink composition while allowing adequate solvent content for proper nozzle flow and clogging prevention.
Data Source
AI summary
Azo compounds represented by general formula (1) or salts thereof are provided as highly water-soluble colorants which have hues of yellow, orange, brown or red, and excellent color development properties and which, when used in various recording processes, particularly in an inkjet recording process, ensure various excellent fastnesses such as light fastness, ozone fastness, and fading balance. Ink compositions containing the colorants are also provided. In general formula (1), R1 to R8 are each independently a hydrogen atom, C1-4 alkyl, C1-4 alkoxy, or the like; and X is C1-8 alkylenediamino, xylylenediamino, or the like.