Inkjet Printing Metallic Colors via Segmented Pigment Layers
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Solution Overview
Problem
Current inkjet printing technologies face challenges in producing high-quality pearlescent and metallic colors, particularly silver and gold, due to the large particle size of available pigments which clog nozzles and result in inferior metallic gloss and reliability issues, while existing solutions either require high temperatures or are economically unviable.
Innovation Solution
An inkjet printing method using a layer of pearlescent or metallic pigment with a volume mean particle size of at least 3.0 μm, combined with a white inkjet ink having an average particle size between 250 and 400 nm, allowing for reliable printing and achieving brilliant metallic colors without the need for high-temperature sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If large particle size pigments (5-50 μm) are used for metallic and pearlescent colors, then excellent metallic gloss and color quality are achieved, but the pigments clog inkjet nozzles (25 μm diameter) and printing reliability deteriorates
Solution Approach 1:
The printing process is segmented into two distinct stages: first applying a base layer containing large particle size metallic/pearlescent pigments (5-50 μm) for excellent gloss and color quality, then applying a separate white inkjet ink layer (250-400 nm particles) that can be reliably jetted through standard nozzles. This segmentation allows each layer to fulfill its specific function without compromising the other.
Solution Approach 2:
The metallic/pearlescent pigment layer is applied in advance as a base layer before the white inkjet ink layer. This preliminary action ensures that the large particles are already in place to provide the desired metallic effect, while the subsequent white ink layer (with much smaller particles) can be reliably deposited without clogging issues, thereby preserving both quality and reliability.
2Reliability
If particle size is reduced to enable inkjet printing, then nozzle clogging is prevented, but metallic gloss deteriorates and colors become greyish
Solution Approach 1:
The ink system is segmented into two functional components: a base layer with large particles (5-50 μm) that provides excellent metallic gloss, and a white inkjet ink layer with small particles (250-400 nm) that ensures reliable printing. By separating these functions into distinct layers, the patent avoids the trade-off between particle size and metallic effect.
Solution Approach 2:
The final printed structure is a composite of two layers: the first layer contains metallic/pearlescent pigments in a binder system suitable for large particles, while the second layer is a white inkjet ink with fine particles optimized for inkjet deposition. This composite structure combines the advantages of both large and small particle systems.
3Manufacturing precision
If high-temperature sintering is used to create metallic conductive inks, then solid conductive patterns are formed, but thermal stability requirements exclude many common packaging materials
Solution Approach 1:
The patent replaces the thermal sintering process (high-temperature mechanical/thermal system) with a UV-curing chemical process. Instead of heating substrates to high temperatures to fuse metal particles, the invention uses UV irradiation to initiate polymerization and crosslinking of the binder system, thereby forming solid, adherent patterns at temperatures compatible with heat-sensitive packaging materials.
Solution Approach 2:
The curing temperature parameter is fundamentally changed from high temperature (sintering >150°C) to low temperature (UV curing at ambient or slightly elevated temperatures). This parameter change enables the use of thermally sensitive substrates while still achieving complete curing and adhesion through photochemical reactions rather than thermal processes.
4Reliability
If nozzle diameter is increased to accommodate large particles, then particle passage is enabled, but fine image details and thin lines cannot be printed
Solution Approach 1:
The printing process is segmented into two sequential steps: first printing the metallic/pearlescent pigment layer (with large particles) using a nozzle configuration that accommodates these particles, then printing the white inkjet ink layer (with fine particles 250-400 nm) using standard fine-nozzle configurations. This segmentation allows each layer to be printed with appropriate nozzle characteristics, preserving both particle passage capability and fine detail resolution.
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 the production of high-quality, variable data with excellent pearlescent and metallic colors on a wide range of substrates, including thermally sensitive materials, with improved adhesion and reliability, and simplifies the printing process by using a single metallic pigment layer for silver and gold colors.
Implementation Method 1
achieving brilliant metallic colors
Implementation Method 2
white inkjet ink containing a white pigment having an average particle size between 250 and 400 nm
Implementation Method 3
inkjet printing a colour image
Data Source
AI summary
A method of inkjet printing a color image including a metallic or pearlescent color includes the steps of applying on part of an ink receiver a layer containing a pearlescent or metallic pigment having a volume mean particle size of at least 3.0 μm as measured by laser diffraction; and inkjet printing on part of the layer containing the pearlescent or metallic pigment a layer with a white inkjet ink containing a white pigment having an average particle size between 250 and 400 nm as measured by differential centrifugal sedimentation.