Multi-Pass Inkjet Printing with Periodic UV Curing
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Solution Overview
Problem
Inkjet printing technologies face limitations in achieving high gloss and gamut while maintaining print quality and adhesion, particularly in multi-pass printing modes, where traditional methods often result in poor reproduction of fine text and increased dot gain due to faster curing or lower gloss materials.
Innovation Solution
A method of multi-pass inkjet printing that involves jetting radiation-curable ink in pairs of layers, where one layer is printed without immediate curing and the next layer is applied, allowing for simultaneous curing of both layers with a sufficient UV dose applied only to every other pass, enabling ink spread and resulting in higher gloss and gamut without compromising adhesion or print quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional multi-pass printing applies UV curing to every pass, then adhesion is improved, but gloss and gamut deteriorate due to restricted ink spread
Solution Approach 1:
The patent applies UV curing periodically rather than continuously - specifically curing every other pass (odd passes) while leaving even passes uncured. This periodic action allows ink to spread freely during uncured passes (improving gloss and gamut) while maintaining adhesion through cured passes. The alternating cure/non-cure pattern creates optimal conditions for both adhesion and optical quality.
Solution Approach 2:
The patent applies UV curing in advance during odd passes to establish a cured foundation layer before applying subsequent uncured layers. This preliminary curing action ensures adhesion is established early in the multi-pass process, allowing later layers to spread freely without compromising bond strength.
2Productivity
If faster curing materials are used to improve productivity, then print speed is improved, but dot gain increases and fine text reproduction deteriorates
Solution Approach 1:
By curing only every other pass rather than every pass, the patent reduces the frequency of curing events. This allows ink to spread more before each cure event, reducing dot gain and improving fine text reproduction while maintaining overall productivity through efficient use of UV energy.
Solution Approach 2:
The patent applies a preliminary cured layer that serves as a stable foundation, allowing subsequent uncured layers to be applied and spread without excessive dot gain. This staged approach enables better control over ink placement and fine detail reproduction.
3Strength
If lower gloss materials are used to improve adhesion, then adhesion is improved, but gamut and visual quality deteriorate
Solution Approach 1:
The alternating cure/non-cure pattern allows the ink to achieve high gloss and gamut during uncured passes through maximum spread, while cured passes provide the adhesion foundation. The final image combines both properties because the uncured layers spread over the cured foundation.
Solution Approach 2:
The patent creates a composite structure where cured and uncured ink layers coexist in the final image. The cured layers provide adhesion and structural integrity, while the uncured layers provide gloss and color saturation, achieving both adhesion and visual quality simultaneously.
4Strength
If more UV curing passes are applied to improve cure strength, then adhesion is improved, but production time increases and productivity deteriorates
Solution Approach 1:
By curing every other pass instead of every pass, the patent reduces the total number of UV curing events by approximately 50%. This periodic approach maintains sufficient adhesion strength while significantly reducing production time and increasing productivity.
Solution Approach 2:
The patent applies UV curing to only the necessary passes (odd passes) rather than all passes, achieving sufficient adhesion strength with partial curing action. This avoids excessive curing that would unnecessarily extend production time.
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 allows for increased formulation latitude in ink composition, achieving higher gloss and gamut with maintained print quality by ensuring a strong cure throughout the image-building process, enhancing the overall performance and quality of the printed image.
Implementation Method 1
An inkjet ink comprising a radiation-curable monomer and a photoinitiator... exposing all of the layers of ink to actinic radiation to cure the ink
Data Source
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AI summary
The present invention provides a method of multi-pass inkjet printing comprising: (i) providing an inkjet ink comprising a radiation-curable monomer and a photoinitiator; (ii) jetting the ink via a printhead on to a substrate, wherein the ink is applied in multiple passes of the printhead with respect to the substrate, with each pass jetting a portion of ink in a layer on the substrate, with a first layer being jetted directly on to the substrate and subsequent layers being jetted onto the preceding layer, to build an image formed of the multiple layers; and (iii) exposing all of the layers of ink to actinic radiation to cure the ink, wherein the order of jetting the layers and curing is that pairs of layers are applied to the substrate without exposing the first layer of the pair to actinic radiation prior to the second layer of the pair of layers being applied, curing the pair of layers simultaneously by exposing the pair of layers to actinic radiation, and repeating until the image is formed.