Shear-Dependent Ink Printing for Dark Surface Concealment
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Solution Overview
Problem
Existing inkjet printing methods struggle with bleeding when printing on dark or porous surfaces, leading to inadequate concealment of underlying colors and compromised design quality.
Innovation Solution
A printing method involving the deposition of a first liquid with specific viscosities at varying shear rates, followed by the application of a second liquid, using a printing apparatus with units designed to manage these viscosities, to form a thick film that conceals the underlying color and suppress bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional inkjet printing is used on dark or porous surfaces, then printing can be performed, but bleeding occurs and concealing properties are insufficient
Solution Approach 1:
The invention changes the viscosity parameter of the ink to resolve the contradiction between concealing properties and bleeding. By formulating ink with specific viscosity characteristics (1.00×10³ mPa·s or more at shear rate of 1 s⁻¹ and 3.50×10² mPa·s or less at shear rate of 5,000 s⁻¹), the ink forms a thick film that provides excellent concealing properties while the viscosity control prevents bleeding during the printing process.
Solution Approach 2:
The invention applies local quality by creating a thick film structure at the printed surface that provides enhanced concealing properties. The ink is designed to form a substantial film thickness on dark or porous substrates, providing localized high-quality concealment where it is most needed, while maintaining appropriate flow characteristics to prevent bleeding.
2Reliability
If ink viscosity is increased to improve concealing properties, then film thickness increases, but discharge stability deteriorates
Solution Approach 1:
The invention applies dynamics by designing ink with non-Newtonian flow characteristics where viscosity changes dynamically with shear rate. The ink maintains high viscosity at low shear rates (providing thick film formation and concealing properties) but reduces viscosity at high shear rates (ensuring stable discharge from nozzles). This dynamic viscosity adjustment resolves the contradiction between concealing properties and discharge stability.
Solution Approach 2:
The invention changes the viscosity parameter as a function of shear rate to simultaneously achieve good concealing properties and discharge stability. The ink formulation is designed so that viscosity is 1.00×10³ mPa·s or more at shear rate of 1 s⁻¹ (for thick film formation) and 3.50×10² mPa·s or less at shear rate of 5,000 s⁻¹ (for stable discharge), effectively resolving the contradiction through parameter optimization.
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 method effectively prevents bleeding and enhances the concealing properties of the printed layer, resulting in robust and durable coatings on surfaces with dark or irregular textures.
Implementation Method 1
a first liquid having a viscosity of 1.00×10³ mPa·s or more at a shear rate of 1 s−1 at 25° C. and a viscosity of 3.50×10² mPa·s or less at a shear rate of 5,000 s−1 at 25° C.
Data Source
AI summary
A printing method is provided that includes depositing, on an object to be coated, a first liquid having a viscosity of 1.00×103 mPa·s or more at a shear rate of 1 s−1 at 25° C. and a viscosity of 3.50×102 mPa·s or less at a shear rate of 5,000 s−1 at 25° C., and performing printing by discharging a second liquid from a nozzle onto the first liquid deposited on the object to be coated.