Ink Composition with Polymeric Dispersant for High Pigment Loading
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Solution Overview
Problem
Conventional inkjet ink compositions and recording methods for commercial or industrial use face challenges such as limited color reproduction range, image spreading on non-absorbing media, long-term discharge stability issues due to high pigment concentration, and potential cracking of cured films, especially when trying to achieve wide color gamut.
Innovation Solution
An ink composition comprising isoindoline-based pigment, a polymeric dispersant, an alkylammonium salt of a sulfonated derivative of a disazo-based yellow colorant, a polymerizable compound, and a polymerization initiator, which is cured using actinic radiation, providing improved dischargeability, stability, and image saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pigment concentration is increased to obtain wide color reproduction range, then color saturation is improved, but viscosity increases and long-term discharge stability deteriorates
Solution Approach 1:
The patent introduces a specific dispersant as an intermediary substance to facilitate pigment dispersion. The dispersant has a molecular structure containing a polyether chain and a polyol chain, which acts as a mediator between pigment particles and the ink vehicle, enabling high pigment concentration while maintaining low viscosity and excellent discharge stability.
Solution Approach 2:
The patent optimizes the molecular weight ratio between the polyether chain and polyol chain of the dispersant, specifically setting the ratio within 0.3 to 2.0. This parameter optimization allows the dispersant to effectively reduce viscosity while maintaining pigment dispersion, thereby achieving high pigment concentration with improved discharge stability.
2Quantity of substance
If ink composition droplets are increased to obtain wide color reproduction range, then color saturation is improved, but image cracking occurs due to excessive film thickness
Solution Approach 1:
The patent modifies the chemical composition parameters of the ink vehicle, specifically incorporating a dispersant with controlled molecular weight ratio and using a radiation-curable resin system. These parameter changes enable the formation of flexible cured films that can accommodate higher ink loads without cracking, thus achieving wide color gamut while maintaining film integrity.
3Ease of operation
If conventional inkjet ink composition is used on non-absorbing recording medium, then dischargeability is achieved, but image spreading occurs due to long drying time
Solution Approach 1:
The patent replaces the conventional thermal drying mechanism with radiation curing (UV or electron beam irradiation). This substitution eliminates the need for long drying times, as the ink composition cures immediately upon irradiation, preventing image spreading while maintaining excellent dischargeability on non-absorbing recording media.
Solution Approach 2:
The patent utilizes the phase transition from liquid ink to crosslinked gel structure through radiation-induced polymerization. This phase transition occurs instantly upon irradiation, locking the ink droplets in place and preventing spreading, thereby achieving both good dischargeability and sharp image definition.
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 solution enables the formation of high-saturation images with improved long-term discharge stability and curability, addressing the limitations of conventional inkjet systems by enhancing color reproduction and preventing image spreading on non-absorbing media.
Implementation Method 1
a polymerization initiator (E), wherein the ink composition is cured by irradiation with actinic radiation
Implementation Method 2
a piezo inkjet system, in which ink is discharged by utilizing deformation of a piezoelectric element
Implementation Method 3
a thermal inkjet system, in which droplets of ink are discharged by utilizing the phenomenon of boiling of the ink by means of thermal energy
Data Source
AI summary
An ink composition comprising: (A) an isoindoline-based pigment; (B) a polymeric dispersant; (C) an alkylammonium salt of a sulfonated derivative of a disazo-based yellow colorant; (D) a polymerizable compound; and (E) a polymerization initiator.