Ink Set Treatment Liquid for Hydrophobic Substrates
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Solution Overview
Problem
Existing image recording methods using aqueous ink on substrates with low water wettability result in smaller-than-desired images due to water repellent effects, leading to decreased density and striped unevenness, as current treatments fail to stabilize resin fine particles and improve wettability effectively.
Innovation Solution
An ink set comprising a colorant and a treatment liquid with water-insoluble resin particles containing sulfo groups and aromatic or alicyclic structures, which are unevenly distributed on the substrate to enhance hydrophilicity and prevent swelling, maintaining desired droplet size and image density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a water-soluble polymer compound is used in the treatment liquid to improve wettability, then the wettability of the substrate surface is improved, but the polymer compound cannot be in a particle state and thus the wettability improvement effect is insufficient
Solution Approach 1:
The invention changes the physical state parameter of the polymer compound from dissolved (water-soluble) to particulate (water-insoluble resin particles). This parameter change allows the polymer to be applied in a particle form that can effectively improve wettability while maintaining stability in the treatment liquid, resolving the contradiction between insufficient wettability improvement and the inability to use particle state
Solution Approach 2:
The invention creates a composite treatment liquid containing water-insoluble resin particles with specific functional groups (carboxyl, sulfo, or phosphoric acid groups) combined with dispersing agents. This composite formulation enables the hydrophobic resin particles to be stably dispersed and effectively improve substrate wettability, overcoming the limitation of using only water-soluble polymers
2Object-affected harmful factors
If resin fine particles containing sulfo group or phosphoric acid group are used to improve wettability, then the wettability improvement effect is expected, but the fine particles are swollen in the treatment liquid with time and thus likely to be coarsened
Solution Approach 1:
The invention introduces a dispersing agent as an intermediary substance between the hydrophobic resin particles and water. The dispersing agent adsorbs onto the particle surfaces, providing steric or electrostatic repulsion that prevents particle aggregation and swelling over time, thus maintaining particle size stability while preserving wettability improvement capability
Solution Approach 2:
The invention changes the solubility parameter of the resin from water-soluble to water-insoluble, creating a distinct phase separation between the resin particles and water. This parameter change, combined with appropriate particle size control and dispersing agent selection, prevents unwanted swelling while maintaining stable dispersion and wettability improvement function
3Object-affected harmful factors
If a surfactant is used for improving the wettability of the substrate surface, then the wettability is improved, but the effect of improving the wettability using a surfactant is not sufficient
Solution Approach 1:
The invention changes the form of wettability improvement from molecular-level surfactant action to particle-level resin fine particle action. The resin particles provide a more substantial and durable wettability improvement effect compared to surfactants, as they form a physical layer on the substrate surface that continuously promotes water spreading
Solution Approach 2:
The invention creates a composite system combining hydrophobic resin particles with hydrophilic functional groups and dispersing agents. This composite structure provides superior wettability improvement compared to simple surfactants, as the hydrophobic particle core adheres to the substrate while the hydrophilic surfaces and dispersing agents promote water spreading
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 set achieves stable image recording with desired density and prevents striped unevenness by improving substrate wettability and maintaining droplet size, thus enhancing image quality on hydrophobic substrates.
Implementation Method 1
improving the wettability of a surface of the substrate... water contact angle is 70° or greater
Implementation Method 2
water-insoluble resin particles... containing at least one constitutional unit derived from a second monomer that has at least one structure selected from an aromatic ring structure and an alicyclic structure... preventing swelling
Implementation Method 3
a compound that causes the colorant in the ink composition to aggregate... destabilizes the dispersed state of the pigment in the ink
Data Source
AI summary
Provided are an ink set including: an ink composition which contains a colorant and water, and a treatment liquid which contains water-insoluble resin particles having a constitutional unit derived from a first monomer that contains at least one group selected from a sulfo group and a salt of the sulfo group and a constitutional unit derived from a second monomer that has at least one structure selected from an aromatic ring structure and an alicyclic structure, a compound that causes the colorant in the ink composition to aggregate, and water; and an image recording method.