Cationic Coating Composition for Ink-Jet Printability
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Solution Overview
Problem
Uncoated papers face challenges in ink-jet printing due to their fiber structure, which affects ink absorption and visibility, and tracing papers are not absorbent and sensitive to moisture, while cationic coatings can coagulate with plastic pigments, impacting printability and substrate stability.
Innovation Solution
A coating composition is developed with a plastic pigment having a glass transition temperature of at least 50°C, combined with cationic substances and anionic or cationic pigments, which improves ink-jet printability without altering the substrate's appearance or feel, using a process that includes adding cationic substances and pigments in specific steps to maintain stability and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating composition containing cationic substances and plastic pigments is prepared, then the ink-jet printability is improved, but the plastic pigments coagulate and the coating composition becomes unstable
Solution Approach 1:
The patent applies preliminary action by adding the cationic substance to the coating composition before adding the plastic pigment. This pre-establishes the cationic environment that prevents pigment coagulation during subsequent ink-jet printing, while maintaining composition stability throughout the coating process
2Reliability
If a coating is applied to improve ink-jet printability, then the printing quality improves, but the optical and haptic properties of the substrate are altered
Solution Approach 1:
The patent applies local quality by creating a coating with specific local properties: the cationic substance and plastic pigment combination provides ink-jet printability enhancement at the molecular level, while the overall coating structure maintains the macroscopic surface properties (optical and haptic characteristics) similar to uncoated substrate
3Reliability
If cationic coating compositions are used to fix ink-jet inks, then the ink fixation is improved, but the binders coagulate and the coating composition becomes unstable
Solution Approach 1:
The patent applies preliminary action by establishing the cationic environment through cationic substances before adding binders and other sensitive components. This pre-established environment prevents coagulation of binders and maintains composition stability throughout the coating process while ensuring effective ink fixation
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 significantly enhances printability while maintaining the optical and haptic properties of uncoated papers, preventing irregularities in ink-jet printing and ensuring the substrate's stiffness and bulk remain unchanged, with improved transparency and homogeneity for tracing papers.
Implementation Method 1
Since the inks used in ink jet printing are anionic, it has proven advantageous to apply the coatings applied to the surface of a substrate from cationic coating compositions. The cationic charge then remains in the dried coating composition and permanently fixes subsequently applied ink jet inks.
Implementation Method 2
The coating composition is applied to at least one side of the substrate and dried.
Data Source
AI summary
The invention relates to a method for producing a coating composition. Said method comprises the following steps: a) an aqueous composition is provided which contains at least one plastic pigment that has a minimum glass transition temperature (Tg) of 50°C; and b) a cationic substance is added which contains salts of divalent or trivalent cations. At least one anionic pigment that has an average particle diameter ranging from 1 nm to 500 nm is added to the coating composition before the cationic substance is added in step b), and/or at least one cationic pigment that has an average particle diameter ranging from 1 nm to 500 nm is added to the coating composition after adding the cationic substance in step b). Also disclosed is a coated substrate which is coated with said coating composition.