Inkjet Paper Coating with Cationic Polymer for Ink Adhesion
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Solution Overview
Problem
Aqueous inkjet inks, particularly dye-based, suffer from poor adhesion to paper substrates, leading to instability under environmental changes, smearing, and sensitivity to surface friction, requiring improved inkjet receiving sheets with enhanced ink adhesion, optical density, waterfastness, and bleed resistance.
Innovation Solution
An inkjet recording sheet with a substrate coated using a composition comprising a cationic polymer dispersion copolymer of 50 mole percent acrylamide-dimethylaminoethylacrylate benzyl chloride quaternary salt and 50 mole percent acrylamide, combined with starch, inorganic salt, pigment, or water, which improves ink adhesion and stability through a film forming polymer composition applied via size press or calendaring machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If aqueous inkjet inks are used for printing, then environmental friendliness and non-combustibility are improved, but ink adhesion to paper substrate deteriorates
Solution Approach 1:
The patent applies a coating composition containing cationic polymer, starch, and inorganic salt as an intermediary layer between the aqueous inkjet ink and paper substrate. This coating layer enhances ink adhesion by providing cationic sites that interact with anionic dye molecules, preventing ink from detaching during environmental changes while maintaining the environmental benefits of aqueous inks.
Solution Approach 2:
The invention uses a composite coating composition combining multiple materials (cationic polymer, starch, inorganic salt) to achieve synergistic effects. The cationic polymer provides adhesion sites, starch contributes to coating stability and waterfastness, and inorganic salt enhances optical density and ink fixation, collectively solving the adhesion problem while preserving environmental compatibility.
2Object-affected harmful factors
If aqueous inkjet inks are used, then toxicity is reduced, but resistance to surface friction and environmental changes deteriorates
Solution Approach 1:
The coating composition acts as a protective intermediary layer that shields the printed ink from surface friction and environmental exposure. The cationic polymer and inorganic salt components create a durable interface that maintains ink integrity during handling and environmental variations, enhancing reliability without compromising the low-toxicity advantage of aqueous inks.
Solution Approach 2:
The invention modifies the surface properties of the paper substrate by applying a coating with specific chemical parameters (cationic charge density, starch content, inorganic salt composition). These parameter changes create a surface that is more resistant to friction and environmental stress while maintaining compatibility with aqueous inks, thereby improving reliability without increasing toxicity.
3Ease of operation
If dye-based aqueous inks are used, then ease of nozzle passage is improved, but image stability under environmental changes deteriorates
Solution Approach 1:
The coating composition serves as a stabilizing intermediary between the dye-based ink and the paper substrate. The cationic polymer in the coating forms strong interactions with anionic dye molecules, anchoring them securely to the substrate. This prevents ink detachment and feathering during environmental changes while maintaining the dye's solubility and ease of nozzle passage characteristics.
Solution Approach 2:
The composite coating system combines cationic polymer, starch, and inorganic salt to provide multiple functions: the cationic polymer ensures dye fixation and image stability, starch contributes to waterfastness and coating integrity, and inorganic salt enhances optical density. This composite approach stabilizes the image without affecting the dye's ability to pass through inkjet nozzles easily.
4Object-affected harmful factors
If aqueous inkjet inks are used, then combustion safety is improved, but optical density and color depth deteriorates
Solution Approach 1:
The invention uses a composite coating containing inorganic salt (such as titanium dioxide or barium sulfate) combined with cationic polymer and starch. The inorganic salt particles provide high refractive index and scattering properties that significantly enhance optical density and color depth. Simultaneously, the coating's water-based composition maintains combustion safety, achieving both goals through material composition synergy.
Solution Approach 2:
The invention modifies the optical parameters of the printed surface by incorporating inorganic salt particles with specific refractive indices and particle size distributions into the coating composition. These parameter changes increase light scattering and absorption, thereby enhancing optical density and color depth while the aqueous-based coating system preserves combustion safety characteristics.
5Object-affected harmful factors
If aqueous inkjet inks are used, then environmental compatibility is improved, but waterfastness and bleed resistance deteriorates
Solution Approach 1:
The coating composition acts as a water-resistant intermediary layer between the aqueous ink and paper substrate. The starch and inorganic salt components create a hydrophobic barrier that prevents water from penetrating to the ink layer, thereby preventing bleeding and improving waterfastness. This intermediary layer maintains environmental compatibility by being water-based itself while providing water resistance to the printed image.
Solution Approach 2:
The composite coating system combines starch (which provides waterfastness through gelatinization and film formation) with inorganic salt particles (which create hydrophobic barriers and enhance water resistance) and cationic polymer (which provides adhesion). This composite structure achieves improved waterfastness and bleed resistance while maintaining the environmental compatibility of aqueous-based formulation.
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 significantly enhances ink adhesion, lightfastness, waterfastness, and resistance to rubbing and bleeding, resulting in improved print quality and handling characteristics.
Implementation Method 1
a composition engaged to at least a portion of the at least one surface, the composition comprising at least one cationic polymer
Implementation Method 2
The humectant is a nonvolatile cosolvent (such as glycerin or ethylene glycol), which absorbs water from the air
Data Source
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AI summary
The invention provides an ink jet recording sheet which is highly resistant to printings smearing, running, feathering, color bleeding, or fading when wet, humid, or exposed to intense or continual light. The recording sheet has a solid substrate and a composition coating the solid substrate. The composition comprises a cationic polymer as well as starch, inorganic salt, pigment, and water. The composition can further comprise a non-ionic polymer. The coating tightly binds both pigment based inkjet inks and dye based inkjet inks. The composition is easy to apply and the ink jet recording sheet can be easily formed with a standard size press device.