Copolymer Ink Binder for High Density and Stable Ejection
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Solution Overview
Problem
Aqueous pigment inks used in inkjet recording methods face challenges with low water resistance, light resistance, and image density on plain paper, particularly with pigment dispersing agents that have issues with storage stability and pigment dispersiveness.
Innovation Solution
A novel copolymer with specific structural units, including a naphthyl group for adsorption and a pendant carboxyl group, is used as a binder resin and pigment dispersing agent, enhancing pigment dispersion and stability on the paper surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the concentration of the pigment in the ink is high, then image density is improved, but viscosity becomes high which leads to reduction in ejection stability
Solution Approach 1:
The copolymer acts as an intermediary between the pigment and the aqueous medium. It contains both hydrophilic groups (carboxyl groups) that interact with water and hydrophobic groups (naphthyl groups) that interact with the pigment, enabling high pigment concentration while maintaining ink流动性 and ejection stability
Solution Approach 2:
The invention uses a composite copolymer structure combining different functional groups: carboxyl groups for water solubility and pigment binding, and naphthyl groups for enhanced pigment interaction and surface retention. This composite structure allows the ink to maintain both high pigment concentration and proper flow characteristics
2Stability of the object's composition
If a graft polymer containing an aromatic ring at a side chain is used as a pigment dispersing agent, then pigment dispersiveness is improved, but long-term storage stability cannot be secured
Solution Approach 1:
The invention changes the chemical structure parameters of the dispersing agent by using a copolymer with specific functional groups (carboxyl and naphthyl groups) in defined ratios. This structural parameter change enables both improved pigment dispersiveness and enhanced long-term storage stability that the graft polymer alone cannot achieve
3Manufacturing precision
If a polymer with calcium index value is used to allow pigment to remain on paper surface, then image density is improved, but storage stability of the ink is low
Solution Approach 1:
The copolymer serves as a dual-function intermediary: the carboxyl groups provide calcium binding capability for paper surface interaction, while the naphthyl groups maintain pigment interaction. This intermediary structure achieves both high image density on paper and long-term storage stability
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 copolymer achieves high image density and long-term storage stability, preventing beading and improving pigment dispersiveness, even at high printing speeds.
Implementation Method 1
a copolymer of the present invention includes a structural unit represented by the following General Formula (1), a structural unit expressed by the following Structural Formula (1), and a structural unit represented by the following General Formula (2)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
To provide a copolymer including: a structural unit represented by the following General Formula (1) where X represents a hydrogen atom or a cation; a structural unit expressed by the following Structural Formula (1); and a structural unit represented by the following General Formula (2) where R is a hydrogen atom or a methyl group, L is a single bond or -(CH2)n-O-CO- where n is an integer in a range of from 2 through 18, and a carbonyl carbon atom in the -(CH2)n-O-CO- is bound to naphthyl.