Aqueous Inkjet Ink Stability via Polyurea Resin and Dispersant Mediator
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Solution Overview
Problem
The design of aqueous resin-based inkjet inks is challenging due to colloid stability issues, particularly with pigments like quinacridones and diketopyrrolopyrroles, which have hydrogen bonding capabilities, making it difficult to combine them with poly(urethane) or poly(urea) resins for industrial applications requiring excellent light fastness and physical properties.
Innovation Solution
An aqueous inkjet ink composition that includes a poly(urea) or poly(urethane) resin particle and specific compounds represented by general formulas I and II, which are added during the dispersion step or as additives, to enhance stability and compatibility with quinacridone or diketopyrrolopyrrole pigments, using interfacial polymerization to form nanocapsules with a polymeric shell and functional groups for electrostatic stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If quinacridone or DPP pigments with hydrogen bonding capabilities are combined with poly(urethane) or poly(urea) resins, then excellent light fastness and physical properties are achieved, but colloid stability deteriorates due to hydrogen bonding interactions
Solution Approach 1:
A dispersant compound containing both hydrophilic groups (carboxylic acid, sulfonic acid, phosphonic acid or their salts) and hydrophobic groups (alkyl, aryl, or alkaryl) is introduced as an intermediary between the pigment and resin. This dispersant mediates the interaction by providing electrostatic stabilization through its charged groups while the hydrophobic portions interact with the pigment surface, preventing direct hydrogen bonding between pigment and resin that would cause aggregation.
Solution Approach 2:
The invention changes the chemical parameters of the system by selecting specific dispersant compounds with controlled ratios of hydrophilic to hydrophobic groups. By adjusting the types and amounts of ionic and nonionic groups in the dispersant, the colloidal stability is optimized while maintaining the desired pigment-resin interactions for light fastness and physical properties.
2Productivity
If aqueous resin-based inkjet ink is designed for industrial applications, then productivity and economic efficiency are improved, but jetting reliability deteriorates due to stability issues causing printer downtime
Solution Approach 1:
The dispersant acts as a mediator that ensures long-term colloidal stability of the ink formulation, preventing pigment aggregation and resin flocculation during storage and jetting. This stability maintenance ensures consistent jetting performance and reduces printer downtime, thereby improving reliability without compromising productivity.
Solution Approach 2:
The dispersant provides beforehand cushioning by pre-establishing electrostatic repulsion barriers between pigment particles and resin droplets. This preventive measure cushiones against potential aggregation and instability issues before they can occur during storage or jetting, ensuring continuous reliable operation.
3Strength
If poly(urea) or poly(urea) resins are used in aqueous inkjet ink, then excellent physical properties are achieved, but compatibility with hydrogen bonding pigments deteriorates
Solution Approach 1:
The dispersant compound serves as an intermediary that bridges the compatibility gap between poly(urea)/poly(urea) resins and hydrogen bonding pigments. The dispersant's dual nature with charged hydrophilic groups and nonpolar hydrophobic groups allows it to simultaneously interact with both the resin and pigment surfaces, enabling their coexistence in the same aqueous medium without direct adverse interactions.
Solution Approach 2:
The ink formulation becomes a composite system consisting of resin particles, pigment particles, and dispersant molecules working together. The dispersant forms a composite interface layer around pigment particles that is compatible with both the hydrophobic resin and the polar pigment surfaces, achieving versatility in material compatibility while maintaining excellent physical properties.
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 achieves excellent stability and jetting reliability, extending the shelf life and print quality of the inks, ensuring consistent performance and reducing downtime in industrial printing processes.
Implementation Method 1
a compound having both ionic and nonionic groups which provides electrostatic stabilization
Implementation Method 2
interfacial polymerization to form nanocapsules with a polymeric shell
Implementation Method 3
compounds which may be used as additives during the dispersion step or as additives in the ink formulation
Data Source
AI summary
An aqueous inkjet ink comprising a resin particle selected from the group consisting of a poly(urea), a poly(urethane) and combinations thereof, a pigment selected from the group consisting of quinacridones and diketopyrrolopyrrole pigments and a compound represented by general formula (I) or general formula (II).