Cationic Polymer Coating Composition for Inkjet Print Stability
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Solution Overview
Problem
Existing inkjet printing media face challenges in achieving superior image quality due to issues with ink dry time, optical density, and edge sharpness, particularly when using low-cost cellulose substrates, as ink fixatives can precipitate negatively charged binders, leading to unstable coating compositions.
Innovation Solution
A coating composition comprising pigments, a surface active substance, and a metal-containing polymeric complex formed from a polymeric latex, polyvinyl alcohol, and a metallic salt, which improves ink optical density, color saturation, and reduces dry time while maintaining surface smoothness and whiteness, and prevents coagulation of pigment particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional anionic polymer binders are used in coating compositions, then compatibility with negatively charged pigment slurry is improved, but compatibility with cationic ink fixative deteriorates, causing precipitation
Solution Approach 1:
The patent changes the charge parameter of the binder from anionic to cationic. The cationic polymer binder has a positive charge that is compatible with both the negatively charged pigment slurry and the cationic ink fixative, preventing precipitation and ensuring coating stability. This parameter change resolves the contradiction by making the binder adaptable to multiple components in the coating composition.
2Manufacturing precision
If ink fixative is added to coating compositions to improve inkjet printing qualities, then ink absorption and optical density are improved, but binder stability deteriorates due to precipitation
Solution Approach 1:
The patent changes the charge parameter of the binder to cationic, which is compatible with the cationic ink fixative. This prevents the precipitation that would otherwise occur between the ink fixative and anionic binders, allowing the ink fixative to be added in sufficient quantities to improve print quality while maintaining coating stability.
3Ease of manufacture
If low-cost cellulose substrates are used, then manufacturing cost is reduced, but image receiving properties and sheet quality deteriorate
Solution Approach 1:
The patent uses a composite binder system comprising cationic polymer binder combined with metal-containing polymeric complex. This composite binder provides enhanced binding strength and surface properties that compensate for the inferior quality of low-cost cellulose substrates, improving image receiving properties while maintaining cost-effectiveness.
Solution Approach 2:
The patent changes the charge parameter of the binder to cationic, which enhances compatibility with inkjet inks and fixatives. This improvement in chemical compatibility compensates for the lower quality of inexpensive substrates, enabling good print quality on cost-effective materials.
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 coating composition enhances print quality by improving ink optical density, color saturation, and edge sharpness, while maintaining the physical attributes of the media, such as surface smoothness and whiteness, and prevents coagulation issues, resulting in a stable and effective image-receiving layer for inkjet printing.
Implementation Method 1
the cationic ions adversely impact the stability of negatively charged binders (anionic polymers). Indeed, ink fixative can precipitate binders
Implementation Method 2
Surface characteristics of the printing paper have a primary influence on qualities of ink jet printing
Implementation Method 3
The function of the binder is, mainly, by forming a continuous film, to bond the pigment particles together, as well as to bind the pigments particles to the base substrate
Data Source
AI summary
A coating composition includes pigments or a mixture of pigments, a surface active substance and a metal containing polymeric complex. The metal containing polymeric complex contains a metallic salt, a polymeric latex and polyvinyl alcohol (PVA), wherein the polyvinyl alcohol has a molecular weight ranging from about 10,000 to about 65,000.