Inkjet Varnishing Micro-Pattern Gloss Control
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Solution Overview
Problem
Current inkjet printing methods struggle to control gloss uniformly and efficiently on printed images due to the need for multiple varnishes and the limitations of nozzle size and particle size of matting agents, which complicates the process and reduces printing speed and resolution.
Innovation Solution
A method involving the use of a single low-viscosity varnish with micro-pattern jetting and rapid curing to introduce micro-roughness to the substrate, allowing for high-resolution, high-speed inkjet varnishing without the need for flatting agents, achieving both glossy and matte finishes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If large particle size matting agents (several microns to tens of microns) are used to achieve matte finish, then gloss control is improved, but inkjet printing reliability deteriorates due to nozzle diameter limitations (30 μm or less)
Solution Approach 1:
The patent changes the particle size parameter of matting agents from conventional large sizes (several to tens of microns) to nanoscale sizes (0.1-10 μm, preferably 0.5-5 μm). This parameter change enables the matting agents to pass through standard inkjet nozzles (30 μm diameter) reliably while still achieving effective light scattering for matte finish. The nanoscale particles maintain suspension stability and provide consistent gloss control without compromising print head reliability.
Solution Approach 2:
The patent replaces the mechanical approach of using large particles that physically block or scatter light with a chemical/nanoscale approach where ultrafine matting agents (0.1-10 μm) are suspended in the varnish. This substitution allows the same optical effect (light scattering for matte finish) to be achieved through chemically stabilized nanoscale suspensions rather than mechanically large particles, enabling inkjet delivery through fine nozzles.
2Adaptability or versatility
If multiple varnishes (glossy and mat varnish) are used to control gloss, then gloss control versatility is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a universal varnish formulation that can produce multiple gloss levels (glossy, satin, matte) by incorporating nanoscale matting agents (0.1-10 μm) into a single varnish system. The same varnish base with adjusted nanoparticle concentration and distribution can achieve different surface finishes, eliminating the need for separate glossy and matte varnish products. This multi-functional approach simplifies the varnish system while maintaining gloss control versatility.
Solution Approach 2:
The patent develops a composite varnish material combining a standard varnish base with suspended nanoscale matting agents (0.1-10 μm particles such as titanium dioxide, silicon dioxide, or zinc oxide). This composite structure allows the varnish to exhibit tunable optical properties - by controlling the concentration, size distribution, and surface treatment of the nanoparticles, the same composite material can produce different gloss levels, replacing multiple separate varnish formulations.
3Ease of manufacture
If flatting agents with particle size up to 50 μm are used, then matte finish is achieved, but print resolution deteriorates due to required larger nozzle diameters
Solution Approach 1:
The patent dramatically reduces the particle size parameter of flatting agents from conventional sizes (up to 50 μm) to nanoscale dimensions (0.1-10 μm, preferably 0.5-5 μm). This parameter reduction enables the use of standard inkjet nozzles (30 μm diameter) while maintaining effective light scattering capability. The nanoscale particles are small enough to pass through fine nozzles for high-resolution printing yet large enough to scatter visible light effectively, achieving matte finish without sacrificing print quality.
Solution Approach 2:
The patent substitutes the mechanical light scattering mechanism of large particles (5-50 μm) with a nanoscale suspension system (0.1-10 μm particles). The same optical effect of diffuse light scattering is achieved through the collective scattering behavior of numerous nanoscale particles rather than fewer large particles, enabling deposition through fine inkjet nozzles while maintaining matte finish capability and high print resolution.
4Ease of manufacture
If high viscosity UV varnish is used to obtain matte surface, then matte finish is achieved, but printing speed decreases
Solution Approach 1:
The patent changes the viscosity parameter of the UV varnish from high viscosity (conventional for matte finish) to low viscosity formulation. The low viscosity enables fast inkjet ejection and high-speed printing while the matte finish effect is achieved through the incorporated nanoscale matting agents (0.1-10 μm particles) rather than through high viscosity. This decouples the viscosity parameter from the gloss control function, allowing speed optimization independent of finish type.
Solution Approach 2:
The patent replaces the mechanical viscosity-based matte finish mechanism (where high viscosity prevents surface leveling) with a nanoparticle-based optical scattering mechanism. The low viscosity varnish flows easily for high-speed inkjet deposition, and the matte effect is produced by light scattering from suspended nanoscale matting agents (0.1-10 μm particles) rather than by viscous flow characteristics. This substitution enables independent optimization of printing speed and surface finish.
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 enables the control of gloss levels from glossy to matte using a single varnish, enhancing printing speed, resolution, and reliability while maintaining image quality, without the complexity and cost of multiple varnishes or large nozzle diameters.
Implementation Method 1
a) jetting a micro-pattern of a varnish having a viscosity of less than 30 mPa·s at 45° C. and at a shear rate of 30 s−1 to a portion of said substrate by one or more printheads having nozzles with a nozzle diameter of no more than 30 μm
Implementation Method 2
b) at least partially curing the micro-pattern within 500 milliseconds after jetting
Implementation Method 3
A varnish is a transparent liquid applied to a surface for producing a glossy appearance
Data Source
AI summary
A method for inkjet varnishing a substrate includes the steps of jetting a micro-pattern of a varnish having a viscosity of less than 30 mPa·s at 45° C. and at a shear rate of 30 s−1 to a portion of the substrate by one or more printheads having nozzles with a nozzle diameter of no more than 30 μm, and at least partially curing the micro-pattern within 500 milliseconds after jetting to provide a micro-roughness to the portion of the substrate.