Aqueous Black Ink Composition for Neutral Density and Ozone Resistance
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Solution Overview
Problem
Current ink jet recording methods face challenges in producing high-density, neutral black images with low chroma and no color tone, particularly due to ozone gas fastness issues and nozzle clogging, which affect image durability and quality.
Innovation Solution
An aqueous black ink composition containing specific azo compounds with a maximal absorption wavelength between 550 to 660 nm, formulated with particular substituents and crosslinking groups, is used to enhance image density and resistance to ozone gas, while minimizing nozzle clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional water-soluble coloring matters are used in ink jet recording, then the ink can be easily formulated and applied, but the recorded images suffer from poor ozone gas fastness and significant discoloration
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of coloring matters to include specific azo compounds with maximal absorption wavelengths between 550-660 nm and particular substituents (R1-R8 groups). This structural parameter change enables the ink to achieve both ease of formulation and high ozone gas fastness, resolving the contradiction between manufacturability and reliability.
Solution Approach 2:
The invention uses composite materials by combining specific azo compounds with particular substituent groups (R1-R8) and crosslinking groups (X) to create a novel ink composition. This composite approach allows the ink to simultaneously maintain ease of formulation while achieving superior ozone gas resistance and image durability.
2Quantity of substance
If coloring matters with high print density are used to reduce solid content, then nozzle clogging is reduced and cost is lowered, but achieving neutral black with low chroma and no color tone becomes difficult
Solution Approach 1:
The patent employs parameter changes by selecting azo compounds with specific absorption wavelength parameters (550-660 nm) and controlled solid content (0.1-20% by mass). This precise parameter control enables the ink to achieve neutral black with low chroma while maintaining high print density and preventing nozzle clogging.
Solution Approach 2:
The invention applies local quality by carefully selecting and positioning specific substituent groups (R1-R8) and crosslinking groups (X) at particular locations in the azo compound molecular structure. This localized structural optimization enables the ink to simultaneously achieve color neutrality, high density, and low chroma characteristics.
3Productivity
If porous white inorganic substances are used in the ink-receiving layer to speed up drying and reduce bleeding, then image quality is improved, but discoloration and fading due to ozone gas is significantly observed
Solution Approach 1:
The patent converts the harmful effect of ozone gas that causes discoloration into a beneficial outcome by using specific azo compounds that are inherently resistant to ozone oxidation. The ink composition maintains high drying speed on porous substrates while the special coloring matters prevent the typical ozone-induced fading, effectively converting the problematic interaction into a durable image system.
4Shape
If multiple coloring matters are mixed to prepare black ink, then neutral hue can be achieved, but discoloration increases due to decomposition by light or ozone gas
Solution Approach 1:
The patent extracts the problematic aspect of using multiple separate coloring matters by consolidating the color-neutralizing function into a single specially designed azo compound structure. This extraction eliminates the decomposition issues associated with mixing multiple coloring matters while maintaining neutral black hue through the inherent molecular structure of the azo compound with specific substituents.
Data Source
AI summary
Disclosed is a water-based black ink composition which exhibits a low intensity, colorless and neutral black color and provides a black recorded image the printed image of which has high density. The ink composition comprises at least one compound represented by the formula (1) or a salt thereof as a pigment (I) and an azo compound having λmax within the range of 550-660 nm as a pigment (II). In the formula (1), R1 to R8 independently represent a hydrogen atom; a halogen atom; a sulfo group; a carboxy group; a sulfamoyl group; a carbamoyl group; a C1-C4 alykyl group; a C1-C4 alkoxy group; and a C1-C4 alkoxy group, or the like substituted with at least one group selected from a group consisting of a hydroxy group, a C1-C4 alkoxy group, a hydroxy C1-C4 alkoxy group, a sulfo group and a carboxy group. X represents a bivalent cross-linking group.