Print Medium With Porous Pigment Coating for Flexographic Printing
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Solution Overview
Problem
Flexographic printing faces challenges with uncoated substrates producing matte prints and coated substrates requiring intermediate drying steps due to slow ink absorption, leading to smearing and reduced productivity, especially in polychrome printing applications where high ink amounts are used.
Innovation Solution
A print medium with a substrate coated on one side with a permeable layer of pigment particles having a monomodal pore diameter distribution, volume defined polydispersity, and specific pore characteristics, allowing for rapid ink absorption without intermediate drying steps, enhancing print quality and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a coated substrate is used to provide glossy prints, then print quality is improved, but intermediate drying steps are required due to slow ink absorption
Solution Approach 1:
The patent applies a porous coating layer comprising pigment particles with controlled pore size distribution (30-80 nm median pore diameter) on the substrate surface. This porous structure enables rapid ink absorption while maintaining surface gloss, eliminating the need for intermediate drying steps between printing units in polychrome flexographic printing.
Solution Approach 2:
The patent modifies the physical parameters of the coating layer by controlling pigment particle size (0.5-5 μm), pore diameter distribution (30-80 nm median), and coating thickness (1-20 μm). These parameter optimizations enable the coating to simultaneously achieve glossy surface appearance and rapid ink uptake capability, resolving the contradiction between print quality and productivity.
2Object-affected harmful factors
If water-based inks are used to eliminate pollution, then environmental friendliness is improved, but ink bleeding and smudging occur due to slow substrate absorption
Solution Approach 1:
The porous coating layer with optimized pore size distribution rapidly absorbs water-based ink, preventing ink bleeding and smudging. The capillary action within the porous structure quickly wicks away the aqueous solvent, ensuring print stability while maintaining environmental friendliness through water-based ink usage.
Solution Approach 2:
The patent employs a disposable porous coating layer that is applied to the substrate surface. This coating acts as a temporary absorption medium that quickly takes up the water-based ink during printing, then allows the printed material to proceed to subsequent processing steps without requiring the substrate itself to have inherent rapid absorption properties.
3Productivity
If uncoated substrates are used for rapid ink absorption, then productivity is improved, but print quality deteriorates due to matte surface
Solution Approach 1:
The patent applies a porous coating layer with controlled pore size distribution (30-80 nm median pore diameter) on the substrate surface. This porous structure enables rapid ink absorption while maintaining surface gloss, eliminating the need for intermediate drying steps between printing units in polychrome flexographic printing.
Solution Approach 2:
The patent creates a composite structure by applying a pigment-based porous coating layer (containing particles such as calcium carbonate, titanium dioxide, or clay) onto the substrate. This composite coating combines the substrate's mechanical properties with the coating's optical (glossy) and functional (rapid absorption) properties, achieving both high print quality and productivity.
4Manufacturing precision
If multiple layers of ink are applied for polychrome printing, then color accuracy is improved, but smearing occurs without intermediate drying steps
Solution Approach 1:
The porous coating layer with optimized pore size distribution (30-80 nm median pore diameter) rapidly absorbs the ink solvent, preventing ink migration and smearing between printing units. This enables true wet-on-wet polychrome printing where multiple ink layers are applied without intermediate drying, maintaining both color accuracy and preventing smearing.
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 print medium absorbs ink quickly, preventing smearing and allowing high-speed printing with improved sheet gloss and brightness, enabling the production of high-quality flexographic prints without the need for intermediate drying steps.
Implementation Method 1
a permeable coating layer comprising pigment particles, wherein said pigment particles, when in form of a compacted bed, have a monomodal pore diameter distribution, a volume defined polydispersity expressed as full width at half maximum height (FWHM) from 36 to 80 nm, and a volume defined median pore diameter from 30 to 80 nm
Data Source
AI summary
The present invention concerns a print medium and a method of producing such a print medium. In particular, the present invention is directed to a print medium comprising a substrate having a first and a reverse side, and at least one coating layer on of the substrate sides.