Azo Ink Composition for Ozone-Fast High-Density Black Printing
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Solution Overview
Problem
Conventional black inks for inkjet recording lack sufficient ozone gas fastness, light fastness, moisture fastness, and water fastness, and existing dyes for black ink are either shallow in hue, have poor color rendering properties, or contain metal ions posing safety concerns.
Innovation Solution
Development of an azo compound with specific functional groups that enhance water solubility and stability, allowing for high-density black inkjet printing with improved fastness properties, particularly ozone gas fastness, and ease of synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dyes are used for black ink, then the ink can be easily synthesized and applied, but the ozone gas fastness, light fastness, moisture fastness, and water fastness are insufficient
Solution Approach 1:
The patent modifies the chemical structure of azo dyes by introducing specific substituents (sulfonate groups, hydroxyl groups, and aromatic hydrocarbon groups) to enhance fastness properties. The general formula (I) allows systematic variation of R1-R7 groups to optimize both performance and synthesizability, resolving the contradiction between improved reliability and manufacturing ease.
Solution Approach 2:
The invention creates a composite molecular structure combining azo chromophores with multiple functional groups (sulfonate for solubility, hydroxyl for stability, aromatic groups for fastness). This composite approach integrates multiple beneficial properties into a single dye molecule, achieving superior fastness without excessive synthesis complexity.
2Illumination intensity
If polyazo coloring matter with increased conjugate system is used to deepen hue, then the hue density increases, but the storage stability of aqueous solution and ink deteriorates due to low water solubility
Solution Approach 1:
The patent introduces sulfonate groups (R1-R7) which dramatically increase water solubility of the polyazo compound. This parameter change allows the extended conjugate system to maintain both deep hue density and excellent storage stability in aqueous solutions, resolving the contradiction between hue intensity and compositional stability.
Solution Approach 2:
The invention places hydrophilic sulfonate groups at specific positions on the aromatic rings while maintaining the extended conjugated system for hue depth. This local differentiation allows different parts of the molecule to fulfill different functions: the conjugated system provides hue density while the sulfonate groups ensure water solubility and storage stability.
3Productivity
If porous white inorganic substance is used in ink-receiving layer to dry ink faster and decrease bleed, then image quality improves, but discoloration or fading caused by ozone gas occurs noticeably
Solution Approach 1:
The patent develops azo dyes with enhanced ozone resistance that can withstand the oxidative environment created by porous inorganic layers. The specialized molecular structure converts the potentially harmful ozone exposure into a manageable condition, allowing the benefits of fast drying and bleed reduction to be realized without significant discoloration.
Solution Approach 2:
The invention modifies the dye's chemical parameters by introducing ozone-resistant structural features (specific substituent patterns on the azo groups). These parameter changes enable the dye to maintain color stability even when used with porous inorganic substances that accelerate drying but increase ozone exposure.
4Illumination intensity
If azo metal-complex coloring matter is used for black ink, then the hue can be enhanced, but safety concerns arise due to metal ion content and ozone gas fastness remains insufficient
Solution Approach 1:
The patent removes metal ions from the dye structure entirely, creating a purely organic azo compound system. This extraction of harmful metal components eliminates safety concerns while maintaining hue enhancement through optimized organic substituents. The sulfonate and hydroxyl groups provide both color intensity and ozone resistance without requiring metal complexes.
Data Source
AI summary
An azo compound represented by the following Formula (1) or a salt thereof, and an ink composition comprising the same(wherein, each of R1, R2, R5, R6 and R7 independently represents a hydrogen atom, a carboxyl group, a sulfo group and the like, each of R3 and R4 independently represents a hydrogen atom, a sulfo group, a nitro group, a (C1 to C4) alkyl group (which may be substituted by a hydroxyl group or a (C1 to C4) alkoxy group), a (C1 to C4) alkoxy group (which may be substituted by a hydroxyl group, a (C1 to C4) alkoxy group, a sulfo group or a carboxyl group) and the like, and n represents 0 or 1, respectively).