Solvent-Based Inkjet Ink Dispersant Parameter Optimization
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Solution Overview
Problem
Solvent-based inkjet inks face challenges in achieving a balance of low viscosity, stability, and resistance while maintaining color vividness and reproducibility, particularly in outdoor advertising applications where high gloss, wide color gamut, and alcohol resistance are required, often compromising productivity due to high pigment dispersion viscosity and resin content.
Innovation Solution
A solvent-based inkjet ink formulation comprising a pigment, organic solvent, and a dispersant with specific molecular weight and functional groups, such as polyethyleneimine with oxyalkylenecarbonyl side chains, which reduces viscosity and improves stability, using a vinyl chloride-vinyl acetate-based resin and specific pigments like C.I. Pigment Yellow 83, to enhance coloration and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the proportion of resin is increased to improve alcohol resistance, then alcohol resistance is improved, but viscosity increases making it difficult to achieve satisfactory alcohol resistance
Solution Approach 1:
The patent changes the chemical parameters of the dispersant by specifying a weight-average molecular weight of 5,000 to 20,000, an acid value of 5 to 20 mg KOH/g, and an amine value of 20 to 50 mg KOH/g. These parameter changes enable the dispersant to effectively reduce pigment dispersion viscosity while allowing sufficient resin content (1-20% by weight) to be added for improving alcohol resistance of the ink coating film.
2Reliability
If pigment concentration is increased to improve coloration vividness, then coloration vividness is improved, but ink viscosity increases causing deterioration of inkjet dischargeability
Solution Approach 1:
The patent optimizes the dispersant parameters (molecular weight 5,000-20,000, acid value 5-20, amine value 20-50) to enable effective pigment dispersion at lower concentrations. This allows achieving satisfactory coloration vividness while maintaining ink viscosity within the range of 1 to 20 mPa·s at 25°C, preserving inkjet dischargeability.
3Reliability
If dispersion time is lengthened to achieve desired gloss and color gamut, then gloss and color gamut are improved, but productivity is reduced
Solution Approach 1:
The patent specifies precise dispersant parameters (weight-average molecular weight 5,000 to 20,000, acid value 5 to 20, amine value 20 to 50) that enable rapid and effective pigment dispersion. This achieves the desired gloss, color gamut, and color reproduction quality while significantly reducing the dispersion time required, thereby improving productivity.
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 stability, resistance to whitening, and superior coloration vividness and reproducibility, allowing for efficient inkjet printing on non-absorbent substrates with improved alcohol resistance and reduced dispersion time.
Implementation Method 1
the dispersant has a main chain composed of a polyethyleneimine and a side chain having at least an oxyalkylenecarbonyl group
Implementation Method 2
the dispersant has a weight-average molecular weight (Mw) of 5,000 to 20,000, an acid value (mg KOH/g) of 5 to 20, an amine value (mg KOH/g) of 20 to 50
Implementation Method 3
the organic solvent comprises at least one solvent selected from the group consisting of glycol monoester-based solvents, glycol diether-based solvents and lactate ester-based solvents
Implementation Method 4
the dispersant has a main chain composed of a polyethyleneimine and a side chain having at least an oxyalkylenecarbonyl group
Data Source
AI summary
The present invention relates to a solvent-based inkjet ink containing at least a pigment, an organic solvent, a binder resin and a dispersant, wherein the dispersant has a weight average molecular weight (Mw) of at least 5,000 but less than 50,000, an acid value (mgKOH/g) of 5 to 20, and an amine value (mgKOH/g) of 5 to 50. The present invention enables a dispersion of low viscosity and good stability to be generated in an extremely short dispersion time, and is able to provide an inkjet ink which forms an ink coating film that suffers no whitening and has superior resistance (abrasion resistance and alcohol resistance).