Ink Set Salt Ratio Optimizes Pigment Agglomeration
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Solution Overview
Problem
Inkjet recording methods face challenges in achieving desired image density and scratch resistance, as existing ink sets often establish a trade-off between these two properties, with pretreatment methods failing to effectively retain pigments on the recording medium surface.
Innovation Solution
An ink set comprising an inkjet ink and a pretreatment liquid, where the ink contains a pigment, pigment coating resin, and a first aqueous medium with water, triethylene glycol monobutyl ether, and a diol with a carbon number of 6, and the pretreatment liquid includes a monovalent salt, a divalent salt, and a second aqueous medium, with a specific mass ratio of divalent to monovalent salt, optimizing pigment agglomeration and retention on the recording medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a pretreatment liquid containing resin particles is used to improve scratch resistance, then scratch resistance is improved, but image density deteriorates
Solution Approach 1:
The invention changes the chemical parameters of the pretreatment liquid by specifying precise salt compositions (monovalent salt at 0.1-5% by mass and divalent salt at 0.01-1% by mass) and their mass ratio (4.5-12.0). This parameter optimization enables the liquid to simultaneously improve scratch resistance and maintain image density by controlling pigment agglomeration without excessive resin particle deposition.
Solution Approach 2:
The pretreatment liquid uses a composite salt system combining monovalent salts (NaCl, LiCl, KCl) and divalent salts (CaCl2, MgCl2) in specific proportions. This composite approach creates synergistic effects where monovalent salts provide baseline scratch resistance while divalent salts enhance pigment agglomeration, achieving both improved scratch resistance and maintained image density.
2Reliability
If the mass ratio of divalent salt to monovalent salt is increased to improve pigment agglomeration, then pigment retention is improved, but ejection stability deteriorates
Solution Approach 1:
The invention optimizes the mass ratio of divalent salt to monovalent salt within the specific range of 4.5-12.0. This parameter control ensures sufficient divalent salt concentration for effective pigment agglomeration and retention, while limiting excess divalent salt that would cause precipitation and ejection instability. The balanced ratio achieves optimal pigment retention without compromising ejection stability.
3Strength
If conventional pretreatment methods are used to improve scratch resistance, then scratch resistance is improved, but pigment agglomeration on the surface is insufficient
Solution Approach 1:
The pretreatment liquid employs a composite salt system with both monovalent salts (0.1-5% by mass) and divalent salts (0.01-1% by mass) in a mass ratio of 4.5-12.0. The monovalent salts provide foundational scratch resistance enhancement, while the divalent salts specifically promote pigment agglomeration through stronger ionic interactions. This composite approach simultaneously achieves both objectives that conventional single-salt systems cannot accomplish.
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 both desired image density and excellent scratch resistance by effectively agglomerating pigments on the recording medium surface, using the monovalent and divalent salts' unique reactivity properties in hydrophilic and hydrophobic environments, while the diol with a carbon number of 6 enhances permeability and ejection stability.
Implementation Method 1
The pretreatment liquid includes a monovalent salt, a divalent salt, and a second aqueous medium, with a specific mass ratio of divalent to monovalent salt, optimizing pigment agglomeration and retention on the recording medium
Implementation Method 2
the diol with a carbon number of 6 enhances permeability and ejection stability
Data Source
AI summary
An ink set includes an inkjet ink and a pretreatment liquid. The inkjet ink contains a pigment, a pigment coating resin, and a first aqueous medium. The first aqueous medium contains water, triethylene glycol monobutyl ether, and a diol with a carbon number of 6. The pretreatment liquid contains a monovalent salt, a divalent salt, and a second aqueous medium. The monovalent salt includes at least one of sodium salt, lithium salt, and potassium salt. The divalent salt includes at least one of calcium salt and magnesium salt. The ratio of the mass of the divalent salt to the mass of the monovalent salt is at least 4.5 and no greater than 12.0 in the pretreatment liquid.