Water-Based Inkjet Ink Formulation for Low-Absorption Substrates
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Solution Overview
Problem
Water-based inkjet inks face challenges with poor wet spreading and penetration on low-absorption substrates, leading to image quality issues such as voids and mottling, due to high surface tension and low absorption properties of the substrates, and existing solutions either compromise on discharge stability or drying properties.
Innovation Solution
A water-based inkjet ink formulation using a water-soluble binder resin with a low acid value, combined with a water-soluble organic solvent having a surface tension of 30 to 40 mN/m and a boiling point of 180 to 230°C, which improves wet spreading and drying properties while maintaining discharge stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water-based ink is used for printing on low-absorption substrates, then environmental friendliness and safety are improved, but wet spreading and penetration are worsened due to high surface tension
Solution Approach 1:
The patent modifies the chemical composition parameters of the water-based ink by incorporating specific organic solvents (glycol ethers and glycols) with controlled ratios. This changes the surface tension and evaporation characteristics of the ink, enabling it to spread properly on low-absorption substrates while maintaining environmental safety by avoiding harmful solvents.
Solution Approach 2:
The patent creates a composite ink formulation combining water, organic solvents (glycol ethers and glycols), binders, and pigments in specific ratios. This composite structure allows the ink to achieve both environmental friendliness and proper wetting properties by leveraging the complementary characteristics of each component.
2Manufacturing precision
If polymer particles are used as binder resin to improve image quality, then mottling is reduced, but discharge stability is worsened due to solidification on nozzle surfaces
Solution Approach 1:
The patent changes the molecular weight parameter of the binder resin to a specific range (5,000-50,000), which optimizes the balance between image quality and discharge stability. This parameter adjustment prevents both mottling and nozzle solidification by controlling the resin's flow and film-forming properties.
Solution Approach 2:
The patent applies different functional requirements to different components: the binder resin is optimized for image quality (lower molecular weight for better spreading), while the organic solvent system is optimized for discharge stability (higher boiling point components prevent nozzle solidification). Each component has localized optimization for its specific function.
3Reliability
If high-boiling point solvents like glycerol are used to improve discharge stability, then nozzle solidification is prevented, but drying properties are worsened
Solution Approach 1:
The patent segments the organic solvent system into two functional groups: glycol ethers (higher boiling point, 160-200°C) for discharge stability and glycols (lower boiling point, 180-230°C) for faster drying. This segmentation allows each solvent type to perform its optimal function without compromising the other.
Solution Approach 2:
The patent uses a blended solvent system where the combined effect of multiple solvents exceeds the performance of any single solvent. The synergistic interaction between glycol ethers and glycols provides both discharge stability and acceptable drying properties, achieving more than what either component could accomplish alone.
4Strength
If binder resin with high acid value is used to improve coating film durability, then adhesion is enhanced, but storage stability is worsened
Solution Approach 1:
The patent optimizes the acid value parameter of the binder resin to a specific range (20-80 mg KOH/g), which balances coating film durability and storage stability. This parameter control ensures sufficient adhesion strength while preventing excessive reactivity that would compromise 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 ink achieves excellent image quality with no voids, superior coating film durability, and enhanced storage stability, even on low-absorption substrates, by controlling the surface tension and boiling point of the solvent and using a binder resin with a specific acid value.
Implementation Method 1
because the water that represents the main solvent of water-based inks has a high surface tension, water-based inks tend to exhibit poor wet spreading on low-absorption substrates
Implementation Method 2
when such inks are printed onto low-absorption substrates or the like, achieving satisfactory drying in a short period of time is difficult
Data Source
AI summary
One embodiment relates to a water-based inkjet ink containing at least water, a pigment, a water-soluble organic solvent and a binder resin, wherein the water-soluble organic solvent contains at least a water-soluble organic solvent having a surface tension of 30 to 50 mN/m and a boiling point at 1 atmosphere of 180 to 230°C, in an amount of 15 to 50% by weight relative to the total weight of the water-based inkjet ink, and the acid value of the binder resin is at least 5 mgKOH/g but less than 60 mgKOH/g.