Polyurethane Ink for Scratch-Resistant Coated Paper
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Solution Overview
Problem
Inkjet printing technologies face challenges with dye inks in terms of insufficient light and water resistance, while pigment inks improve durability but suffer from poor glossiness and scratch resistance, especially on coated paper.
Innovation Solution
A set of ink and print medium comprising an ink with polyurethane resin particles, a colorant, and an organic solvent with a specific vapor pressure range, which forms a hard coating film with improved scratch resistance, glossiness, and image density, and includes a compound with a saturated vapor pressure at 100° C. of 65 mmHg or greater but 400 mmHg or less to enhance image driability and prevent blocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pigment inks are used to improve light resistance and water resistance, then image durability is improved, but glossiness deteriorates due to light interference from multiple reflection in pigments
Solution Approach 1:
The invention uses a composite ink formulation containing both pigment particles (for durability) and polymer resin particles (for glossiness and binding). This composite approach allows the ink to simultaneously achieve light resistance, water resistance, and improved surface gloss by combining the beneficial properties of different materials.
Solution Approach 2:
The invention changes the physical and chemical parameters of the ink system by controlling pigment particle size distribution, resin-to-pigment ratio, and solvent composition. These parameter adjustments optimize both the durability (through pigment fixation) and glossiness (through film formation and light reflection properties).
2Reliability
If pigment inks are used to improve light resistance and water resistance, then image durability is improved, but scratch resistance deteriorates because pigments remain on the surface and are easily scratched
Solution Approach 1:
The invention introduces polymer resin particles as an intermediary binding agent that adheres to both the pigment particles and the substrate. This resin matrix embeds the pigment particles, creating a unified coating structure that prevents pigments from being easily scratched off while maintaining their durability benefits.
Solution Approach 2:
The composite ink system combines pigment particles (for durability) with polymer resin particles (for binding and scratch resistance). The resin forms a cohesive film that locks pigments in place, transforming the loose pigment surface into a unified, scratch-resistant coating layer.
3Strength
If polycarbonate polyurethane resin particles are added to improve scratch resistance, then surface hardness is improved, but image driability deteriorates and blocking occurs
Solution Approach 1:
The invention adjusts the glass transition temperature (Tg) parameter of the resin particles to an optimal range that balances film strength with drying performance. By selecting resins with appropriate Tg values and controlling particle size distribution, the ink achieves both scratch resistance and proper driability without blocking.
Solution Approach 2:
The invention uses resin particles with different local properties (varying Tg values, particle sizes, and compositions) to achieve different functions within the same coating: harder regions provide scratch resistance while softer regions maintain driability and prevent blocking during the drying process.
4Manufacturing precision
If ink is attached in high amount to improve image density, then image quality is improved, but blocking occurs and nozzle maintenance properties deteriorate
Solution Approach 1:
The invention changes the ink formulation parameters including resin-to-pigment ratio, solvent composition, and particle size distribution to optimize both image density and nozzle maintenance. The specific organic solvent with controlled vapor pressure enables high ink attachment without excessive drying that would cause blocking.
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 ink achieves excellent scratch resistance, glossiness, and high image density, while preventing blocking and maintaining nozzle maintenance properties, even on coated paper, by using polyurethane resin particles and a specific organic solvent to improve film formation and adhesion.
Implementation Method 1
The at least one organic solvent includes a compound having a saturated vapor pressure at 100° C. of 65 mmHg or greater but 400 mmHg or less
Data Source
AI summary
Provided is a set of an ink and a print medium, the set including an ink and a print medium, wherein the ink includes at least one organic solvent, polyurethane resin particles, a colorant, and water, wherein the at least one organic solvent includes a compound having a saturated vapor pressure at 100° C. of 65 mmHg or greater but 400 mmHg or less, and wherein a sensor output at a critical image peeling point, measured by a microscratching method, of a solid image formed on the print medium in a manner that the ink is attached in an amount of 0.96 mg/cm2 is 600 or greater.