Radiation-Curable Inkjet Ink Gloss via Gellant Crystallization Control
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Solution Overview
Problem
Radiation-curable inkjet inks with gellants typically produce images with low or medium gloss levels, whereas high gloss is desired, and there is a need for gelling radiation curable ink compositions that provide high gloss images.
Innovation Solution
A radiation-curable inkjet ink composition comprising a gellant that includes a fatty acid ester and a fatty acid or fatty alcohol, which forms a nonlinear ester compound that decreases the tendency to crystallize upon cooling, thereby preventing a decrease in gloss levels, and is used in combination with a radiation-curable medium that includes UV-reactive components, inhibitors, solvents, and colorants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a gellant is added to radiation-curable inkjet ink composition to control droplet spreading and prevent color bleeding, then the viscosity increases and droplet spreading is controlled, but the gloss level of the printed image decreases
Solution Approach 1:
The patent applies parameter changes by carefully controlling the concentration range of the gellant (0.1-5 wt%) and selecting specific fatty acid esters with particular molecular weights and structures. By optimizing these parameters, the ink composition achieves sufficient viscosity increase for droplet control while minimizing the negative impact on gloss level.
Solution Approach 2:
The patent uses composite materials by combining the gellant (fatty acid ester) with radiation-curable monomers, oligomers, and other ink components to create a multi-functional ink composition. The gellant provides viscosity control and phase change properties, while the radiation-curable components enable curing, and the formulation balances these functions to maintain acceptable gloss levels.
2Stability of the object's composition
If a gellant is used in radiation-curable inkjet ink to prevent color bleeding, then color bleeding is prevented, but the gloss level remains low or medium
Solution Approach 1:
The patent optimizes the gellant concentration parameter (0.1-5 wt%) and selects fatty acid esters with specific properties (molecular weight 50-5000, particular structural features) to achieve color bleeding prevention while minimizing gloss reduction. The phase change temperature and viscosity characteristics are tuned to balance these competing requirements.
3Productivity
If a small amount of gellant is used to maintain image quality, then viscosity increase is sufficient for droplet control, but the gloss level may still be compromised
Solution Approach 1:
The patent identifies and optimizes critical parameters including gellant concentration (0.1-5 wt%), molecular weight (50-5000), and structural characteristics of the fatty acid ester. By precisely controlling these parameters, the invention achieves effective droplet control at low gellant concentrations while minimizing gloss reduction.
Solution Approach 2:
The patent references and builds upon previous work (EP 3115425, EP 3006518, EP 2554610, EP 3130475) that explored gellant applications in radiation-curable inks, adapting and refining the approach to achieve improved gloss levels while maintaining the beneficial droplet control 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 ink composition efficiently increases viscosity and forms high gloss images when used in an inkjet printing process, preventing blooming and maintaining image quality with a small amount of gellant, resulting in superior print gloss levels.
Implementation Method 1
These inks are fluid at elevated temperature and become (semi-) solid - even if not yet cured- at lower temperatures. The presence of a gellant can cause a viscosity increase in the inkjet ink composition upon cooling of the ink composition.
Implementation Method 2
A radiation-curable component is a component that may react (e.g. polymerize) under influence of suitable radiation, such as electromagnetic radiation, e.g. ultraviolet (UV) radiation.
Implementation Method 3
A photo initiator is a component that improves the efficiency of curing; i.e. increases the polymerization rate when the ink composition is irradiated with suitable radiation, such as UV radiation.
Data Source
Figure 1A~1B
AI summary
The present invention relates to a radiation curable ink composition comprising a gellant. The present invention further relates to an ink set comprising such ink composition. The present invention further relates to a method for making such ink composition and a printing method using such ink composition.