Ink Composition Pigment Dispersivity Stability
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Solution Overview
Problem
Ink-jet recording methods face challenges in achieving high-speed printing with high-quality images due to issues with pigment dispersivity, stability, and curing time, particularly with fine pigment particles that aggregate and increase viscosity, leading to degraded performance and image sharpness.
Innovation Solution
An ink composition containing a polymerizable compound, a pigment, and a specific graft polymer with a polymer skeleton derived from polyvinyls, polyesters, or polyurethanes, which acts as a dispersant to enhance pigment adsorption and stability, allowing for effective curing with active radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the size of pigment particles is decreased to impart the ink composition with a bright color tone and high tinting strength, then the color developing ability is improved, but the pigment becomes difficult to disperse, pigment aggregates are formed, and the viscosity of ink composition increases
Solution Approach 1:
A specific dispersant is introduced as an intermediary substance between the fine pigment particles and the ink composition. This dispersant has molecular structures that simultaneously interact with pigment surfaces and the ink vehicle, preventing aggregation while maintaining stable dispersion. The dispersant acts as a mediator that resolves the conflict between achieving fine particle dispersion and maintaining ink flowability.
Solution Approach 2:
The invention optimizes multiple parameters including pigment particle size distribution, dispersant concentration and molecular weight, and ink composition ratios. By carefully controlling these parameters within specific ranges, the system achieves both fine particle dispersion for color strength and sufficient flowability for inkjet operation, resolving the contradiction between particle fineness and dispersibility.
2Illumination intensity
If the size of pigment particles is decreased to impart the ink composition with a bright color tone and high tinting strength, then the color developing ability is improved, but the viscosity of ink composition increases
Solution Approach 1:
The dispersant serves as a lubricating intermediary between fine pigment particles and the continuous phase, reducing interparticle friction and preventing network formation. This mediator allows the ink to maintain low viscosity despite containing fine pigment particles necessary for high tinting strength.
Solution Approach 2:
The invention optimizes the ratio of dispersant to pigment and selects specific molecular weight ranges for the dispersant. These parameter adjustments ensure that fine particles remain individually dispersed without forming aggregates that would increase viscosity, thereby maintaining both high tinting strength and appropriate ink flow properties.
3Stability of the object's composition
If conventional dispersants are used to disperse fine pigment particles, then the pigment dispersivity is improved, but the ink composition viscosity increases and pigment aggregates form
Solution Approach 1:
A specifically designed dispersant with optimized molecular structure acts as an effective intermediary. This dispersant provides steric and electrostatic repulsion between pigment particles, maintaining stable dispersion without excessive viscosity increase. The molecular structure is tailored to provide adequate separation while minimizing hydrodynamic volume, thus preserving ink discharge ability.
Solution Approach 2:
The invention specifies particular parameter ranges for dispersant molecular weight, concentration, and chemical structure. These optimized parameters ensure that pigment particles remain well-dispersed for stable coloration while keeping the ink composition sufficiently fluid for high-speed inkjet discharge, resolving the contradiction between dispersivity and discharge performance.
4Ease of operation
If the ink is subjected to cyclic temperature variations of heating and cooling, then the ink is accommodated in a cartridge and heated during discharge, but the pigment dispersivity decreases with the passage of time, easily causing thickening or aggregation in the ink
Solution Approach 1:
The dispersant system is designed beforehand to provide protective cushioning against temperature-induced aggregation. The dispersant molecules form protective layers around pigment particles, creating a steric barrier that prevents aggregation during thermal cycling. This pre-established protection cushioning ensures dispersion stability despite repeated heating and cooling operations.
Solution Approach 2:
The invention optimizes the dispersant's thermal stability parameters and its interaction strength with pigment particles. The dispersant is selected or designed to maintain its dispersing efficacy across the operating temperature range, preventing pigment aggregation during heating cycles while ensuring stable dispersion during storage and discharge operations.
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 composition achieves excellent pigment dispersivity and stability, enabling the formation of high-quality images with bright color tones and high tinting strength, suitable for ink-jet recording applications, while maintaining stability over long-term storage and under cyclic temperature variations.
Implementation Method 1
a polymer represented by the following General Formula (2)... which acts as a dispersant to enhance pigment adsorption
Implementation Method 2
curable ink compositions for ink-jet recording that can be cured by irradiation with active radiation
Data Source
AI summary
An ink composition containing at least a polymerizable composition, a pigment, and a polymer represented by General Formula (1): where R1 represents an (m + n)-valent organic linking group, R2 represents a single bond or divalent organic linking group; A1 represents a monovalent organic group having a pigment adsorption structure that contains at least one selected from organic pigment structure, heterocyclic structure, acidic group, group having a basic nitrogen atom, urea group, urethane group, group having a coordinating oxygen atom, hydrocarbon group having 4 or more carbon atoms, alkoxysilyl group, epoxy group, isocyanate group, and hydroxyl group; the n groups A1 and bonds or groups R2 may independently be the same or different; "m" is 1 to 8, "n" is 2 to 9, and m + n is 3 to 10; P1 represents a polymer skeleton; and the m skeletons P1 may be the same or different.