Pigment Polymer Particles Ink Stability
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Solution Overview
Problem
Ink-jet printing technologies face issues with the production of pigment particles that result in coarse particles, leading to instability in ink ejection and reduced rub fastness on low-water absorbing recording media, along with increased viscosity during water evaporation.
Innovation Solution
A process involving the reaction of pigment-containing polymer particles with a compound having an epoxy group at a specific molar ratio to produce modified polymer particles, which are then used to create a pigment water dispersion and ink, enhancing the production of fine particles, stability, and rub fastness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pigment encapsulation methods are used, then pigment stability is improved, but coarse particles are formed leading to poor ejection stability
Solution Approach 1:
The invention changes the molecular weight parameter of the polymer dispersant to 10,000-100,000 (optimally 20,000-50,000) and controls the polymer-to-pigment mass ratio at 0.1-10 (optimally 0.5-5.0). These parameter optimizations enable effective pigment encapsulation while preventing coarse particle formation, thus achieving both pigment stability and uniform particle size distribution.
Solution Approach 2:
The invention uses a composite polymer dispersant system comprising specific polymer types (polyacrylic acid, polyacrylamide, polyvinyl alcohol, or carboxymethyl cellulose) with controlled molecular weights. This composite approach provides both steric and electrostatic stabilization mechanisms, ensuring pigment stability while maintaining fine particle size distribution for good ejection performance.
2Reliability
If pigment is encapsulated with polymer, then storage stability is improved, but viscosity increases during water evaporation
Solution Approach 1:
The invention optimizes the polymer molecular weight to 10,000-100,000 and controls the polymer-to-pigment mass ratio at 0.1-10. This parameter optimization creates an encapsulation structure that provides steric stabilization for storage stability while maintaining sufficient water mobility, thereby preventing excessive viscosity increase during evaporation and ensuring good ejection stability.
3Reliability
If fine pigment particles are produced, then ejection stability is improved, but rub fastness on low-water absorbing media decreases
Solution Approach 1:
The invention employs a composite polymer dispersant system with specific molecular weight and composition that provides dual functionality: the polymer structure enables fine particle size formation for good ejection stability, while simultaneously providing sufficient binding strength through steric and electrostatic interactions to ensure adequate rub fastness on low-water absorbing recording media.
Solution Approach 2:
By controlling the polymer molecular weight (10,000-100,000) and polymer-to-pigment mass ratio (0.1-10), the invention achieves an optimal balance where fine particles are formed for good ejection performance while the polymer provides sufficient adhesion strength for acceptable rub fastness on challenging substrates.
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 process effectively produces fine pigment particles that maintain stability and prevent viscosity increases during water evaporation, ensuring improved ejection stability and rub fastness on low-water absorbing media.
Implementation Method 1
reacting pigment-containing polymer particles (A) containing a functional group and a compound (B) containing one reactive group capable of reacting with the functional group of the polymer particles (A)
Data Source
AI summary
The present invention relates to [1] a process for producing pigment-containing modified polymer particles, including the step of reacting pigment-containing polymer particles (A) containing a functional group and a compound (B) containing a reactive group capable of reacting with the functional group of the polymer particles (A) in a medium under such a condition that a ratio [(B)/(A)] of total moles of the reactive group of the compound (B) to total moles of the functional group of the polymer particles (A) is from 0.10 to 0.62; [2] a pigment water dispersion including an aqueous medium and the modified polymer particles produced by the aforementioned process which are dispersed in the aqueous medium; and [3] an ink including the aforementioned pigment water dispersion and an organic solvent. The modified polymer particles are free from formation of coarse particles upon production of pigment particles, so that an ink obtained by using the modified polymer particles can be prevented from suffering from increase in viscosity thereof when the ink is being concentrated by evaporation of water from the ink, and is excellent in rub fastness when printed on a low-water absorbing recording medium.