Liquid Toner Curing via Second Substrate Oxygen Barrier

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Solution Overview

Problem

Existing digital printing processes using liquid toner struggle with achieving effective adhesion and durability on non-porous substrates like flexible materials and labels, particularly in the food packaging industry, often requiring additional coating steps and higher temperatures for curing, which can lead to thermal stress and potential contamination risks.

Innovation Solution

A digital printing process involving a curable carrier liquid and imaging particles, where a second substrate is applied over the liquid toner, allowing for curing under oxygen-free conditions using actinic radiation or particle beams, eliminating the need for post-printing coatings and reducing thermal stress by embedding imaging particles in a cured layer, thus enhancing adhesion and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate coating unit is used to improve adhesion and gloss, then printing quality is improved, but device complexity and cost increase

Engineering Contradiction:

ImproveadhesionVSAvoidcoating unit

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the coating function with the carrier liquid itself by making the carrier liquid curable. The curable carrier liquid forms a protective and adhesive coating layer that integrates the coating function into the toner composition, eliminating the need for a separate coating unit while maintaining improved adhesion and gloss.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The curable carrier liquid performs multiple functions simultaneously: it acts as the carrier medium for the toner particles, provides adhesion to the substrate, and forms a protective gloss layer. This self-service approach eliminates the need for separate coating operations and reduces device complexity.

Inventive Principle:

Principle #25Self-service

2Reliability

If UV light is used to cure the carrier liquid on porous substrates, then adhesion is improved, but oxygen interference reduces curing effectiveness

Engineering Contradiction:

ImproveadhesionVSAvoidoxygen interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies a second substrate over the transferred liquid toner to create an oxygen-free environment during curing. This inert atmosphere prevents oxygen interference with the UV curing process, ensuring complete and effective curing of the curable carrier liquid while maintaining strong adhesion.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

3Reliability

If higher temperatures are used for curing, then curing effectiveness is improved, but thermal stress and contamination risks increase

Engineering Contradiction:

Improvecuring effectivenessVSAvoidthermal stress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces thermal curing with UV light curing. This substitution allows curing to occur at lower temperatures, effectively eliminating thermal stress and contamination risks associated with high-temperature processes while maintaining complete curing effectiveness through the oxygen-free environment provided by the second substrate.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 results in improved print quality with reduced sensitivity to rubbing, solvents, and sunlight, along with a smoother surface and enhanced gloss, while avoiding the need for separate coatings and allowing for lower temperature curing, making it suitable for food packaging applications.

Implementation Method 1

irradiating the liquid toner with actinic radiation or particle beams to cure the carrier liquid

Methodology Applied

Scientific EffectPhotopolymerisation: Photopolymerisation

Implementation Method 2

an imaging member adapted to sustain a pattern of electric charge forming a latent image on its surface

Methodology Applied

Scientific EffectElectrostatics: Electrostatics

Implementation Method 3

developing the latent image by transferring liquid toner from the development member onto the imaging member in accordance with the pattern

Methodology Applied

Scientific EffectElectrostatic Deposition: Electrostatic Deposition

Data Source

PatentEP3449318B1Digital printing apparatus and process using liquid toner

Publication Date: 2022.05.04 XEIKON MFG NV

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AI summary

A digital printing process for xerography printing with liquid toner, said liquid toner comprising a curable carrier liquid and imaging particles suspended in the carrier liquid, wherein said process comprises: forming a latent image as a pattern of electric charge on a surface of an imaging member; transferring the liquid toner onto a development member; developing the latent image by transferring liquid toner from the development member onto the imaging member in accordance with the pattern; transferring the liquid toner from the imaging member to a first substrate; applying a second substrate on the transferred liquid toner; after application of the second substrate, irradiating the liquid toner with actinic radiation or particle beams to cure the carrier liquid.