Glossy Ink Receptive Coating Resolving Drying Speed and Wet Rub Resistance
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Solution Overview
Problem
Ink receptive coatings containing silica and other highly absorptive inorganic particulates result in rough, low-gloss surfaces and poor wet abrasion resistance, leading to quick abrasive wear and smudging of digitally printed images.
Innovation Solution
A blend of a water reducible polyurethane and an aqueous acrylic copolymer dispersion is used to create a high gloss ink receptive coating that absorbs water and solvents without swelling, maintaining wet rub resistance and eliminating the need for high absorbency fillers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If silica and highly absorptive inorganic particulates are used in ink receptive coatings, then ink receptivity and drying speed are improved, but surface gloss and wet abrasion resistance deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by replacing inorganic silica fillers with specific organic polymer combinations (polyvinyl alcohol with molecular weight 10,000-100,000 and carboxymethyl cellulose with molecular weight 100,000-1,000,000) that have different absorption and surface properties, achieving both high gloss and fast drying
Solution Approach 2:
The patent creates a composite coating material combining polyvinyl alcohol and carboxymethyl cellulose polymers in specific ratios (0.1-10% and 1-20% respectively) to achieve synergistic effects where the combination provides both ink receptivity and surface gloss that individual materials cannot achieve alone
2Productivity
If silica and highly absorptive inorganic particulates are used in ink receptive coatings, then ink receptivity is improved, but wet abrasion resistance deteriorates
Solution Approach 1:
The patent changes the material composition by replacing inorganic particulates with hydrophilic polymers that have high water affinity but maintain structural integrity when wet, providing both ink receptivity and wet abrasion resistance
Solution Approach 2:
The patent uses water-soluble polymers that form a sacrificial protective layer during printing, absorbing ink and solvents to protect the underlying substrate from abrasion while maintaining surface quality
3Productivity
If coatings with high water affinity are used to enable fast drying, then drying speed is improved, but wet rub resistance deteriorates due to swelling and softening
Solution Approach 1:
The patent selects polymers with specific molecular weight ranges (polyvinyl alcohol: 10,000-100,000; carboxymethyl cellulose: 100,000-1,000,000) that balance water affinity for fast drying with sufficient structural strength to maintain wet rub resistance without excessive swelling
Solution Approach 2:
The patent combines two different polymers with complementary properties where polyvinyl alcohol provides fast water absorption for quick drying while carboxymethyl cellulose provides structural stability and wet strength, creating a composite system that achieves both fast drying and wet rub resistance
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 achieves high gloss and rapid drying with excellent wet rub resistance, allowing for immediate handling and packaging of printed images without smudging, while maintaining transparency and preventing ink migration.
Implementation Method 1
The dried coating has high affinity to water and solvents (e.g., humectants, coalescents, etc.) so the water and/or solvents in the ink can be absorbed to facilitate faster drying
Implementation Method 2
Surprisingly the mixture of these two very hydrophilic polymers gave a water resistant film
Data Source
AI summary
The present invention provides a blend of a soft water reducible polyurethane with a high percentage of tethered ethylene oxide rich chains and a harder acrylic copolymer with specified percentages of repeat units from C1-C12 esters of acrylic and/or methacrylic acid and an acid component from combined acrylic and methacrylic acid. The blend forms the binder in a coating that exhibits the possibilities of having high gloss, transparency, and facilitating the conversion of inks applied to the coating to a smudge resistant image in a short period of time after application of the ink.