Bis-urea Gelators for Curable Ink Viscosity Control
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Solution Overview
Problem
There is a need for new gelator molecules suitable for use as phase-change materials in curable inks, particularly for applications like 3D printing, to achieve controlled spread, minimal bleed-through, and rapid build-up of raised print features without intermediate curing steps.
Innovation Solution
The development of bis-urea gelators with specific structures that exhibit a sharp increase in viscosity upon printing, allowing for controlled ink behavior and improved print quality on porous substrates, including the use of Formula I and Formula II structures that can be synthesized by reacting isocyanates with saturated aliphatic amines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional curable inks are used, then the ink can be applied to substrates, but the ink exhibits uncontrolled spread and excessive bleed-through on porous substrates
Solution Approach 1:
The patent utilizes phase-change gelators that undergo a temperature-dependent viscosity transition. At printing temperature, the ink maintains low viscosity for proper flow, then undergoes a sharp viscosity increase as temperature decreases, transforming from liquid to gel state. This parameter change in viscosity controls ink spread and prevents bleed-through on porous substrates.
Solution Approach 2:
The invention employs phase-change materials (gelators) that transition between liquid and gel states based on temperature. This phase transition enables the ink to be liquid during printing for good flow properties, then rapidly gel upon contact with the substrate or during drying, providing controlled spread and minimal bleed-through without requiring intermediate curing steps.
2Manufacturing precision
If intermediate curing steps are used to build raised print features, then the print quality can be improved, but the printing process time increases
Solution Approach 1:
The phase-change gelator provides rapid gelation upon printing, enabling the formation of raised print features in a single pass without intermediate curing steps. The sharp viscosity increase during phase transition creates immediate structural support for raised features, eliminating the need for multiple printing and curing cycles.
Solution Approach 2:
The gelator is pre-formulated into the ink composition at controlled concentrations, so that upon deposition and temperature change, the gelation occurs automatically and rapidly. This preliminary preparation of the gelation mechanism within the ink itself eliminates the need for separate intermediate curing steps to build raised features.
3Manufacturing precision
If gelators are added to curable inks, then the ink viscosity increases sharply upon printing improving controlled spread, but the ink formulation complexity increases
Solution Approach 1:
The patent creates a composite ink formulation by combining curable monomers/oligomers with phase-change gelators. This composite material integrates the beneficial properties of both components: the curability and adhesion from the monomer/oligomer system, and the controlled rheology and bleed prevention from the gelator phase-change behavior.
Solution Approach 2:
The gelator concentration and molecular structure are optimized to achieve the desired phase-change temperature and viscosity increase. By controlling parameters such as gelator concentration (typically 1-20 wt%), molecular weight, and chemical structure, the ink formulation achieves controlled spread without excessive complexity in the overall composition.
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 bis-urea gelators demonstrate a significant increase in ink viscosity, enabling controlled spread and minimal bleed-through, thereby enhancing print quality and allowing for rapid build-up of raised features in 3D printing without intermediate curing steps, resulting in stable and transferable images.
Implementation Method 1
The sharp increase in ink viscosity upon printing offers numerous advantages over non-phase change inks
Data Source
AI summary
The disclosure provides curable inks including a bis-urea gelator having the structure of Formula I.wherein R and R′ each, independently of the other, is a saturated aliphatic hydrocarbon group selected from the group consisting of (1) linear aliphatic groups, (2) branched aliphatic groups, (3) cyclic aliphatic groups, (4) aliphatic groups containing both cyclic and acyclic portions, any carbon atom of the saturated aliphatic hydrocarbon group may be optionally substituted with an alkyl group (cyclic or acyclic), wherein (1) and (2) groups have a carbon number of from about 1 to about 22 carbons, and wherein (3) and (4) groups have a carbon number of from about 4 to about 10 carbons; and X is selected from the group consisting of: (i) an alkylene group, (ii) an arylene group, (iii) an arylalkylene group, and (iv) an alkylarylene group.