Ink Jet Ink Wettability on Nonabsorbent Media
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Solution Overview
Problem
Aqueous ink jet inks struggle to form high-quality images on nonabsorbent recording media due to issues like pin holes, uneven density, and low friction resistance, as they often repel or fail to adhere properly, leading to decreased image durability and glossiness.
Innovation Solution
An ink jet ink composition comprising a pigment, binder resin, water, and specific organic solvents and surfactants, where the surface tension changes minimally with evaporation, ensuring improved wettability and adhesion to nonabsorbent media, and the surfactant concentration is below its critical micelle concentration to prevent pin holes and enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surfactant is added to improve wettability of aqueous ink on nonabsorbent media, then ink repelling is prevented, but surfactant precipitation occurs after drying causing decreased image glossiness and adhesion
Solution Approach 1:
The patent changes the chemical parameters of the aqueous ink by adding specific organic solvents (glycol ethers, glycols, esters, amides) with controlled solubility parameters that match the plasticizer in the nonabsorbent media. This parameter adjustment allows the ink to wet the surface without requiring excessive surfactant, thereby preventing both repelling and surfactant precipitation that would harm glossiness.
Solution Approach 2:
The patent creates a composite ink formulation combining water, organic solvents, surfactants, and resins in specific proportions. The organic solvents work synergistically with the surfactant to achieve proper wettability while controlling surfactant concentration below CMC to prevent precipitation, thus maintaining both reliability and manufacturing precision.
2Reliability
If excess surfactant is added to prevent ink repelling, then wettability improves, but image layer adhesion to recording medium decreases
Solution Approach 1:
The patent precisely controls the surfactant concentration parameter to remain below the critical micelle concentration (CMC). This parameter control ensures the surfactant remains molecularly dispersed and effective for wetting without forming micelles that would precipitate and reduce adhesion. The organic solvents further modulate this parameter balance.
3Reliability
If organic solvent with low surface tension is used to improve wettability, then ink repelling is prevented, but friction resistance does not increase and drying characteristics worsen due to high boiling point
Solution Approach 1:
The patent segments the solvent system into multiple functional components: fast-evaporating solvents (glycol ethers, glycols) that provide initial wetting and rapid drying, and slower-evaporating solvents (esters, amides) that maintain wettability and promote solvent absorption into the media. This segmentation allows each component to optimize its function without compromising overall drying performance.
Solution Approach 2:
The patent adjusts the volatility parameter of the organic solvent mixture by selecting solvents with different boiling points and evaporation rates. The combined vapor pressure and evaporation characteristics are tuned to achieve both good wettability (requiring lower surface tension) and acceptable drying speed (requiring moderate volatility), resolving the contradiction between these two parameters.
4Object-affected harmful factors
If typical aqueous ink is used on nonabsorbent media, then environmental load is low, but pin holes and unevenness occur due to ink repelling
Solution Approach 1:
The patent develops a composite aqueous ink formulation that maintains water as the primary vehicle (low environmental load) while incorporating organic solvents, surfactants, and resins in optimized proportions. This composite structure enables the ink to overcome the repelling effect of nonabsorbent media without switching to environmentally harmful solvent-based inks, thus preserving both ecological benefits and image uniformity.
5Manufacturing precision
If solvent ink is used to achieve high image quality on nonabsorbent media, then glossiness and friction resistance improve, but volatile organic compounds are generated causing environmental and safety issues
Solution Approach 1:
The patent changes the fundamental composition parameter of the ink from organic solvent-based to water-based, fundamentally altering the volatile content and environmental profile. By optimizing the aqueous formulation with specific organic additives held below CMC, the patent achieves glossiness comparable to solvent inks while eliminating the majority of VOC emissions and associated safety concerns.
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 high fineness, excellent glossiness, and high friction resistance on nonabsorbent media, comparable to solvent inks, while maintaining low environmental impact and preventing uneven density and pin holes, thus improving image durability and quality.
Implementation Method 1
a method of preventing repelling of an aqueous ink by adding a surfactant or an aqueous organic solvent having a low surface tension to the ink improves wettability of the aqueous ink to a nonabsorbent medium
Implementation Method 2
A measure for solving these disadvantages involves the addition of a solvent can be absorbed into a polyvinyl chloride sheet to improve friction resistance
Implementation Method 3
In the solvent ink jet inks, the solvents are evaporated, and most of the solvent components dissipate in the air
Data Source
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AI summary
In an ink jet ink containing a pigment, a binder resin, water, an organic solvent, and a surfactant, the surface tension of the ink is on a region defined by γ0 - γx ≥ 1.0 (γ0: surface tension before evaporation, γx: surface tension at an evaporation rate X%) when the evaporation rate X of the ink is in a range of 0 < X(%) ≤ 20; the ink jet ink contains two or more organic solvents; and the content of an organic solvent of which the sum ΣSP of the hydrogen bonding term and the polarity term of the solubility parameter is 8 to 18 MPa1/2 is 30 mass% or more and less than 95 mass% of the total amount of the organic solvents; and the content of the surfactant is less than the critical micelle concentration of the surfactant.