Pigment Composition for Aqueous Ink Stability
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Solution Overview
Problem
Aqueous ink compositions using pigments, such as perinone-based and perylene-based pigments, face challenges with sedimentation and aggregation, leading to instability and limited light resistance and water resistance, which affects the quality and durability of images produced by inkjet recording methods.
Innovation Solution
A pigment composition comprising a perinone-based or perylene-based pigment, water, a resin with specific constitutional units, and compounds like phthalimide or naphthalimide with carboxyalkyl groups, which enhances dispersibility and stability, preventing sedimentation and aggregation through improved interactions between the pigment and the resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a perinone-based or perylene-based pigment is used in aqueous ink, then the ink provides good coloration, but the pigment suffers from sedimentation and aggregation leading to poor storage stability
Solution Approach 1:
The patent introduces a specific dispersing agent with a polymer chain containing both hydrophilic groups (carboxyl, sulfone) and hydrophobic groups (alkyl chains) as an intermediary substance. This dispersing agent mediates between the hydrophobic pigment particles and the aqueous medium, with the hydrophobic portion adsorbing to the pigment surface and the hydrophilic portion extending into the water phase, providing steric stabilization and preventing aggregation and sedimentation of the pigment particles.
Solution Approach 2:
The patent creates a composite dispersion system combining the pigment particles with a specifically designed polymer dispersing agent. The composite structure consists of pigment cores coated with the dispersing agent polymer chains, forming a stable colloidal suspension. This composite approach allows the hydrophobic pigment to be stably dispersed in the hydrophilic aqueous medium through the bridging action of the amphiphilic polymer structure.
2Stability of the object's composition
If a dispersing agent is added to enhance pigment dispersibility, then the dispersion stability improves, but the ink composition becomes more complex
Solution Approach 1:
The dispersing agent polymer performs multiple functions simultaneously: it provides steric stabilization to prevent aggregation, acts as a wetting agent to facilitate pigment surface coverage, and serves as a suspension agent to maintain uniform distribution. This multi-functionality reduces the need for multiple separate additives, simplifying the overall ink composition while achieving comprehensive dispersion stability.
Solution Approach 2:
The patent optimizes specific parameters of the dispersing agent including the molecular weight of the polymer chain, the ratio of hydrophilic to hydrophobic groups, and the concentration of functional groups. By carefully controlling these parameters, the dispersing agent achieves maximum effectiveness at low concentrations, minimizing the impact on composition complexity while maximizing dispersion stability.
3Ease of manufacture
If dye is used as coloring material in aqueous ink, then the ink is easy to formulate, but image blurring occurs and light resistance and water resistance are limited
Solution Approach 1:
The patent replaces traditional dye molecules (which are small and water-soluble but prone to blurring and degradation) with pigment particles that are physically more stable. Although pigments require additional dispersing agents for formulation, the resulting image provides superior durability, light resistance, and water resistance, effectively trading initial formulation simplicity for long-term image quality and reliability.
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 proposed composition achieves excellent sedimentation-inhibiting and aggregation-inhibiting properties, leading to improved storage stability and image quality with enhanced light resistance and water resistance, ensuring better inkjetting stability and image density.
Implementation Method 1
a resin having a constitutional unit represented by Formula 1 and at least one compound selected from the group consisting of a phthalimide compound having a carboxyalkyl group and a naphthalimide compound having a carboxyalkyl group... enhances dispersibility and stability, preventing sedimentation and aggregation
Implementation Method 2
at least one compound selected from the group consisting of a phthalimide compound having a carboxyalkyl group and a naphthalimide compound having a carboxyalkyl group... enhances dispersibility and stability
Implementation Method 3
achieves excellent sedimentation-inhibiting and aggregation-inhibiting properties
Data Source
AI summary
A pigment composition including at least one pigment selected from the group consisting of a perinone-based pigment and a perylene-based pigment, water, a resin having a constitutional unit represented by Formula 1, and at least one compound selected from the group consisting of a phthalimide compound having a carboxyalkyl group and a naphthalimide compound having a carboxyalkyl group; a method for producing thereof; and an aqueous ink composition using the pigment composition. In Formula 1, R1 represents a hydrogen atom or a methyl group, L2 represents —C(═O)O—, —OC(═O)—, or —C(═O)NR2— and R2 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R3 represents an alkyl group having 6 or more carbon atoms.