Multi-Pass UV Inkjet Printing with Partial Curing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inkjet printing with curable inks, particularly UV curable inks, often results in undesirable surface structures such as ridges and balls on substrates like polypropylene, leading to glints, uneven color saturation, reduced color gamut, and a matte finish, which are not preferred in many applications.
Innovation Solution
A method involving multiple passes with partial curing of the ink, where the first pass is partially cured to raise the viscosity and immobilize it on the substrate, while the surface remains wettable for subsequent passes, and full curing is done after all ink has been deposited, using specific wavelengths and inerting environments to control the curing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If curable ink is deposited on substrate and fully cured before next pass, then ink is immobilized and stable, but surface energy decreases and subsequent droplets cannot wet the surface, forming balls and ridges
Solution Approach 1:
The patent applies preliminary action by partially curing the ink after the first pass to stabilize it against spreading, while deliberately leaving the surface uncured to maintain wetting capability for subsequent passes. This selective partial curing resolves the contradiction by performing the stabilization action only where needed (bulk ink) while preserving the surface properties required for further deposition.
Solution Approach 2:
The patent implements local quality by creating a gradient in cure state within the ink layer: the bulk of the ink is partially cured to increase viscosity and prevent spreading, while the exposed surface remains uncured to maintain low surface energy and wetting ability. This spatial differentiation of cure state allows the ink to exhibit both stability and wetting compatibility simultaneously in different regions.
2Manufacturing precision
If curable ink is deposited and fully cured, then ink spreading is prevented, but undesirable surface structures such as ridges and balls form
Solution Approach 1:
The patent applies partial action by using partial curing instead of full curing after the first pass. This partial curing provides just enough stabilization to prevent ink spreading and formation of ridges and balls, while avoiding the excessive curing that would create a high-energy surface and prevent wetting of subsequent passes. The partial cure level is optimized to achieve the minimum necessary stabilization without the harmful side effects of complete curing.
3Stability of the object's composition
If multiple passes are made with full curing between passes, then ink is stable, but color saturation becomes uneven and color gamut is reduced
Solution Approach 1:
The patent applies preliminary action by partially curing the ink after the first pass to provide just enough stabilization to prevent spreading, while leaving the surface uncured to maintain wetting capability. This prevents the formation of ball-shaped droplets in subsequent passes, ensuring uniform color saturation and preserving the color gamut while still providing the necessary ink stability.
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
This approach reduces ink spreading, improves wetting between passes, maintains a glossy finish, and enhances color brilliance by preventing the formation of undesirable surface structures, resulting in a smoother, more vibrant print.
Implementation Method 1
the ink is cured by exposing the ink on the substrate to UV light. The exposure of the ink to UV light initiates a chemical reaction which turns the liquid ink into a solid
Implementation Method 2
partially curing ink deposited in the first pass; partially curing ink deposited in the first pass... to raise the viscosity and immobilize it on the substrate
Data Source
AI summary
A method is disclosed of printing an area of a substrate in a plurality of passes using curable ink, the method comprising depositing a first pass of ink on the area, partially curing ink deposited in the first pass, depositing a second pass of ink on the area, and fully curing the ink on the area. The method finds particular application in the field of inkjet printing, and can afford the advantage of better wetting of ink on the substrate deposited by a previous pass and reducing the problem of ink spreading.