Self-Dispersible Aqueous Ink for Color Density and Cap Deposit Control
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Solution Overview
Problem
Existing aqueous inks using self-dispersible pigments face challenges in achieving high color developability on various recording media and preventing pigment aggregation in the recording head cap, leading to reduced image quality and ejection issues over time.
Innovation Solution
An aqueous ink with a self-dispersible pigment bonded to a specific group represented by general formula (1) and a dynamic surface tension of 52 mN/m or less, which controls pigment adsorption and aggregation, ensuring high color developability and preventing cap deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional self-dispersible pigments are used to achieve high color developability, then image quality improves on some recording media, but pigment aggregates deposit in the recording head cap over time, causing ejection failure
Solution Approach 1:
The patent modifies the chemical structure of the pigment surface group from conventional carboxylic acid groups to a specific group with formula (1) containing both carboxylic acid and hydroxyl groups in defined proportions. This parameter change in the pigment's surface chemistry enables simultaneous achievement of high color developability and suppression of aggregation in the recording head cap, resolving the contradiction between image quality and ejection reliability
Solution Approach 2:
The patent creates a composite pigment structure where the pigment particle surface is modified with a specific composite functional group containing both carboxylic acid groups and hydroxyl groups in a controlled ratio. This composite functional group structure provides dual functionality: enhancing color developability through calcium interaction while preventing aggregation through balanced hydrophilic-hydrophobic characteristics, thus resolving the technical contradiction
2Productivity
If the application amount of ink is reduced, then productivity improves, but image quality with sufficient area factor and high optical density deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the pigment surface group to formula (1) with specific compositional ratios (carboxylic acid groups: 0.1-2.0 mmol/g, hydroxyl groups: 0.1-2.0 mmol/g). This parameter optimization enables the pigment to achieve high optical density and sufficient area factor even at reduced ink application amounts, thereby improving productivity without sacrificing image quality
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 ink achieves excellent color developability on various media and suppresses pigment deposition in the recording head cap, maintaining image quality and ejection performance over extended use.
Implementation Method 1
a self-dispersible pigment in which a group represented by the following general formula (1) is bonded to a surface of a particle of a pigment
Implementation Method 2
the aqueous ink has a dynamic surface tension at 10 milliseconds of 52 mN/m or less
Data Source
AI summary
Provided is an aqueous ink for ink jet using a self-dispersible pigment as a coloring material, the aqueous ink being capable of recording an image having excellent color developability and the aqueous ink being capable of suppressing the deposition of an aggregate in the cap of a recording head. The aqueous ink is an aqueous ink for ink jet including a self-dispersible pigment. The self-dispersible pigment is a self-dispersible pigment in which a group represented by the general formula (1) is bonded to a surface of a particle of a pigment, and the aqueous ink has a dynamic surface tension at 10 milliseconds of 52 mN/m or less. In the general formula (1), M1s each independently represent a hydrogen atom, an alkali metal, ammonium or an organic ammonium, and * represents a bonding position to the surface of the particle of the pigment.