Pre-treatment Radiation for Gel Ink Contact Leveling
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Solution Overview
Problem
Radiation curable gel inks, such as UV curable gel inks, exhibit non-uniform gloss and instability due to offsetting during contact-leveling, which is exacerbated by their low cohesive strength and affinity to materials, making conventional flattening methods unsuitable.
Innovation Solution
Exposing the ink to pre-treatment radiation, specifically short wavelength UV light, before contact-leveling to partially cure the surface and maintain the inner layer's viscosity, allowing for spreading without offset onto contact-leveling apparatus components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If contact-leveling is applied to spread radiation curable gel ink, then gloss uniformity is improved, but ink offset onto apparatus components occurs due to low cohesive strength
Solution Approach 1:
The patent applies a preliminary radiation treatment to the gel ink before contact-leveling to partially cure the surface. This preliminary action increases the cohesive strength of the ink surface, preventing offset onto apparatus components while still allowing the ink to be spread for gloss uniformity. The partial curing creates a stable surface that resists transfer during the leveling process.
Solution Approach 2:
The radiation treatment creates local quality differences within the ink layer by partially curing only the surface portion while leaving the bulk remains soft and spreadable. This localized property change allows the surface to resist offset while the interior maintains its ability to flow and level under the contact member, resolving the contradiction between preventing offset and achieving uniform gloss.
2Manufacturing precision
If conventional flattening methods are used on gel ink, then leveling is achieved, but ink splits and offsets due to affinity to materials
Solution Approach 1:
The patent applies preliminary radiation treatment to increase the cohesive strength of the gel ink before subjecting it to contact-leveling. This preliminary strengthening prevents the ink from splitting and offsetting during the flattening process, while still allowing sufficient spreadability to achieve uniform leveling and gloss.
3Ease of operation
If gel ink is heated to liquid phase for application, then viscosity is reduced for jetting, but ink loses cohesive strength and offsets during contact-leveling
Solution Approach 1:
The patent applies preliminary radiation treatment after the ink has been jetted and deposited on the substrate. This timing allows the ink to maintain its low viscosity for easy jetting, then subsequently gains cohesive strength through radiation-induced partial curing before contact-leveling, preventing offset while preserving the benefits of low-viscosity application.
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
Enables effective leveling and gloss uniformity while preventing ink offset, reducing maintenance and extending apparatus component life by controlling the ink's rheological and surface properties through selective curing.
Implementation Method 1
During this exposure, photoinitiator substances contained in the ink may be irradiated with the UV radiation, and the incident flux converts monomers in the ink into a cross-linked polymer matrix
Data Source
AI summary
A radiation curable gel ink printing system is provided that includes a radiation source configured to emit UV light having short wavelength components. The disclosed systems and methods transport a substrate having radiation curable gel ink deposited thereon to the radiation source to expose the ink to the radiation source. The exposure at the radiation source may be continuous or pulsed. The radiation source may be configured a distance away from the radiation curable gel ink deposited on the substrate. The radiation source pre-treats the radiation curable gel ink before spreading the radiation curable gel ink at a contact-leveling nip at which a contact member applies pressure to the partially cured radiation curable gel ink against the substrate. The radiation curable gel ink is preferentially cured to allow spreading of the radiation curable ink by the contact member while limiting offset of the ink onto the contact member.