Triazine Polymer Dispersant for Pigment Ink Stability
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Solution Overview
Problem
Current pigment inks for inkjet printing face challenges in achieving high optical density and colloidal stability while avoiding agglomeration and requiring excessive organic solvents, and they often result in prints with poor rub fastness and water fastness.
Innovation Solution
A process for preparing polymers with triazine groups that incorporate ionic groups, using a compound of Formula (1) reacted with a diisocyanate and an isocyanate reactive compound, to create a polymer that acts as a dispersant for particulate solids in aqueous vehicles, enhancing colloidal stability and optical density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dispersant stabilised pigment inks are formulated to achieve high colloidal stability, then particle agglomeration is reduced, but optical density on plain paper decreases
Solution Approach 1:
The patent modifies the chemical structure of the dispersant by incorporating ionic groups (such as carboxylate, sulfonate, or phosphate groups) into the polymer backbone. This parameter change in the dispersant's molecular structure enables it to provide both strong colloidal stability through electrostatic repulsion and maintain high optical density by effective pigment surface coverage and light interaction enhancement.
Solution Approach 2:
The invention creates a composite dispersant system combining non-ionic polymeric chains with ionic functional groups. This composite structure allows the dispersant to simultaneously provide steric stabilization from the polymeric portion and electrostatic stabilization from the ionic groups, achieving both high colloidal stability and high optical density properties.
2Illumination intensity
If high optical density is achieved in pigment inks, then print quality improves, but colloidal stability decreases leading to particle agglomeration
Solution Approach 1:
The patent introduces ionic functional groups into the dispersant structure, changing its electrical and chemical parameters. This enables the dispersant to maintain high pigment loading for optical density while the ionic groups provide electrostatic repulsion forces that prevent agglomeration, ensuring colloidal stability.
3Illumination intensity
If conventional dispersants are used to achieve high optical density, then print quality improves, but excessive organic solvent is required
Solution Approach 1:
The patent changes the solvent compatibility parameters of the dispersant by incorporating ionic groups that are highly soluble in aqueous environments. This allows the dispersant to effectively disperse pigment at high concentrations in aqueous or low-organic-solvent formulations, achieving high optical density without requiring excessive organic solvent.
4Reliability
If pigment particles are reduced to sub-micron sizes to prevent agglomeration, then colloidal stability improves, but energy consumption increases
Solution Approach 1:
The patent applies dispersant to the pigment particles before the comminution process. The dispersant adsorbs onto the particle surfaces and provides steric and electrostatic barriers that prevent particle aggregation during milling. This preliminary action reduces the energy required for comminution by eliminating the need to break apart agglomerates and prevents re-agglomeration after particle size reduction.
Data Source
AI summary
A process for preparing a polymer comprising reacting at least the components i) to iii) in any order: i) a compound of the Formula (1): Formula (1) wherein: T1 and T2 independently are HO—, HS— or R1HN—; Q1 and Q2 independently are —NR2—; A1 and A2 independently are an optionally substituted divalent organic linking group; R1 when present is H or an optionally substituted alkyl, aryl or heterocyclyl group; R2 is H or an optionally substituted alkyl, aryl or heterocyclyl group; Z is an HO— group or a group of the Formula (2) or (3); Formula (2) wherein: L is —HN—, —O— or —S—; X is an optionally substituted organic group; Formula (3) wherein: each X independently is an optionally substituted organic group; in both Formulae (2) and (3) the asterisk (*) signifies the point of attachment to the triazine ring: ii) a diisocyanate; iii) an isocyanate reactive compound having at least one ionic group.