Print Medium Paper Coating for Digital Inkjet Printing
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Solution Overview
Problem
Conventional coated printing media fail to meet the requirements for successful digital or inkjet printing due to high absorptive and fast drying needs, often requiring pretreatments like primers, and for flexographic printing, they require dryers to achieve acceptable performance, leading to increased investment and decreased productivity.
Innovation Solution
A print-medium paper with a base of 60% to 100% recycled fibers, featuring a top white side with specific coating layers containing anionic ground calcium carbonate, non-ionic polyvinyl alcohol, water-soluble divalent metal salt, and cationic polymer, which enhances absorption and pigment fixation without the need for primers in digital printing and eliminates the need for dryers in flexographic printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coated printing media are used for digital or inkjet printing, then the printing process can proceed, but the media fail to meet high absorptive and fast drying requirements, requiring pretreatments like primers
Solution Approach 1:
The coating layer is prepared in advance with specific components (anionic ground calcium carbonate, cationic polymer, water-soluble divalent metal salt) that create preliminary conditions for high ink absorption and fast drying, eliminating the need for pretreatments during the printing process
Solution Approach 2:
The coating composition parameters are specifically optimized: anionic ground calcium carbonate particle size (d50 ≤ 300 nm), cationic polymer content (0.1-12% by dry weight), and water-soluble divalent metal salt concentration (0.5-5% wt.-%) are controlled to achieve the required absorption and drying performance
2Productivity
If conventional coated printing media are used for flexographic printing, then printing can proceed, but productivity decreases and dryers are required on or after color printing devices
Solution Approach 1:
The coating layer is designed to inherently provide fast drying performance through its composition (water-soluble divalent metal salt, anionic ground calcium carbonate, cationic polymer), allowing the media to dry flexographic inks without requiring external dryer equipment
Solution Approach 2:
The coating parameters are optimized to enable fast drying: specific particle size distribution of calcium carbonate (d50 ≤ 300 nm), controlled polymer content (0.1-12% by dry weight), and water-soluble salt concentration (0.5-5% wt.-%) create a coating that facilitates rapid ink drying at high printing speeds
3Reliability
If anionic ground calcium carbonate with d50 ≤ 300 nm is used in the coating layer, then ink absorption and pigment fixation are enhanced, but the calcium carbonate is not stable in high conductivity systems
Solution Approach 1:
Water-soluble divalent metal salts and cationic polymers act as intermediaries that stabilize the anionic ground calcium carbonate in high conductivity systems, preventing electrical destabilization of the boundary layer around particles while maintaining the coating's ink absorption and pigment fixation capabilities
Solution Approach 2:
The coating layer is formulated as a composite system combining anionic ground calcium carbonate (for ink absorption) with cationic polymers and water-soluble divalent metal salts (for stability in high conductivity), where the components work synergistically to resolve the contradiction between absorption performance and compositional stability
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 solution allows for direct digital printing without primers and flexible flexographic printing without dryers, improving print quality and productivity by ensuring high absorption and stable ink adhesion, while maintaining brightness and opacity.
Implementation Method 1
The anionic ground calcium carbonate with a particle size d50 of ≤300 nm, when in the form of a compacted bed, has a monomodal pore size distribution, a volume defined pore size polydispersity expressed as full width at half maximum (FWHM) from 40 to 80 nm, and a volume defined median pore diameter from 30 to 80 nm
Implementation Method 2
The external or top white side comprises... at least one cationic polymer... at least one water-soluble salt of a divalent metal ion... to fix the ink pigments onto the surface of the media
Implementation Method 3
The external or top white side comprises... at least one water-soluble salt of a divalent metal ion... to fix the ink pigments onto the surface of the media
Implementation Method 4
aqueous pigmented inks or die inks are used by these technologies; these inks require a high absorptive and fast drying medium... suitable to be printed in a flexographic printer without the need of a dryer
Data Source
AI summary
A print-medium paper comprising a base paper (3) and at least one external or top white side (4) suitable to be printed directly, without the need of the application of a primmer or a bonding agent or external layer substance prior to/on color printing devices, comprising at least one mineral particle which preferable comprises calcium ions and more preferable is anionic ultrafine ground calcium carbonate and at least one binder. The external or top white side (4) preferable comprise a second mineral particle without calcium ions which more preferable is titanium dioxide. Packaging product comprising the print-medium paper claimed. A method for producing the print medium paper claimed. Use of the print medium claimed in a digital printer or a printer based on the use of inkjet technology heads, characterized in that a print medium is printed directly.