Sacrificial Coating for Indirect Printing Intermediate Transfer Member

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Solution Overview

Problem

Indirect inkjet printers face challenges in achieving both good wet image quality and image transfer due to the conflicting requirements of high surface energy for ink spreading and low surface energy for ink release, with existing materials and ink compositions failing to balance these needs effectively.

Innovation Solution

A sacrificial coating composition for the intermediate transfer member, comprising latex polymer particles, hygroscopic materials, and an oil-in-water emulsion with surfactants, is applied to enhance ink wetting, spreading, and image transfer, while also providing mechanical robustness and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a high surface energy blanket material is used to facilitate ink spreading and wetting, then wet image quality is improved, but ink release and transfer to the substrate deteriorates

Engineering Contradiction:

Improvewet image qualityVSAvoidink transfer

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The invention divides the blanket surface into two distinct layers: a base layer made of low surface energy material (silicone, fluorosilicone, fluoropolymer, or hybrid) for ink release, and a sacrificial coating layer made of high surface energy material (polyurethane, polyimide, or their copolymers) for ink wetting. This segmentation allows each layer to perform its specific function optimally without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sacrificial coating is applied locally on the image-receiving surface of the blanket, creating a localized high surface energy region only where ink deposition occurs. The underlying base layer maintains its low surface energy properties in all regions, ensuring ink release capability is preserved while providing enhanced wetting where needed.

Inventive Principle:

Principle #3Local quality

2Reliability

If a low surface energy blanket material is used to facilitate ink release, then image transfer is improved, but ink spreading and wetting deteriorates

Engineering Contradiction:

Improveimage transferVSAvoidwet image quality

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention segments the blanket structure into a base layer for ink release and a sacrificial coating layer for ink wetting. The base layer uses low surface energy materials (silicone, fluorosilicone, fluoropolymer, or hybrid) to ensure excellent ink release, while the sacrificial coating layer uses high surface energy materials (polyurethane, polyimide, or copolymers) to provide the necessary ink spreading and wetting properties.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sacrificial coating acts as an intermediary layer between the ink and the base blanket material. It provides the high surface energy interface needed for ink wetting and spreading, while allowing the underlying low surface energy base layer to perform its ink release function. The sacrificial coating is sacrificed during the transfer process to enable complete ink release.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If ink surface tension is increased to prevent drooling from the print head, then print head performance is improved, but ink spreading on the blanket deteriorates

Engineering Contradiction:

Improveprint head performanceVSAvoidink spreading

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The invention creates a localized high surface energy environment at the blanket surface through the sacrificial coating layer, allowing ink to spread effectively even when the ink itself has higher surface tension. The high surface energy coating compensates for the reduced ink spreading tendency caused by higher ink surface tension, enabling both improved print head performance and adequate ink spreading.

Inventive Principle:

Principle #3Local quality

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 sacrificial coating composition improves wet image quality, facilitates excellent image transfer, and enhances the physical robustness and shelf life of prints, ensuring good wear resistance and water fastness.

Implementation Method 1

a latex comprising polymer particles dispersed in a continuous liquid phase

Methodology Applied

Scientific EffectLatex polymer particle coalescence:

Implementation Method 2

at least one hygroscopic material

Methodology Applied

Scientific EffectHygroscopic absorption:

Implementation Method 3

at least one oil-in-water emulsion; and at least one surfactant

Methodology Applied

Scientific EffectSurfactant action: Surfactant

Implementation Method 4

Spreading of aqueous ink is facilitated by materials having a high energy surface

Methodology Applied

Scientific EffectWetting: Wetting

Data Source

PatentUS10336910B2Sacrificial coating for intermediate transfer member of an indirect printing apparatus

Publication Date: 2019.07.02 GENESEE VALLEY INNOVATIONS LLC

AI summary

An embodiment of the present disclosure is directed to a sacrificial coating composition for an image transfer member in an aqueous ink imaging system. The coating composition is made from ingredients including: a latex having polymer particles dispersed in a continuous liquid phase; at least one hygroscopic material; at least one oil-in-water emulsion; and at least one surfactant.