Core-Shell Aqueous Ink for UV-Stable Mechanical Erasability
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Solution Overview
Problem
Existing erasable inks for porous substrates face issues with color reversibility due to temperature changes, lack of vivid color intensity, and resistance to UV light, and are prone to clogging in writing instruments.
Innovation Solution
The use of core-shell dye microparticles with a water-immiscible organic solvent core and resin shell, having a specific size range, ensures effective mechanical friction removal efficacy, and are prone to vivid color intensity and UV resistance, while preventing clogging in writing instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If thermochromic inks are used for erasability, then erasability by heat friction is improved, but color reversibility occurs at low temperature and UV resistance is poor
Solution Approach 1:
The ink system is segmented into separate functional components: water-soluble dyes for coloration and starch granules for mechanical erasability. This separation eliminates the temperature-dependent color reversal of thermochromic inks while maintaining erasability through physical particle removal.
Solution Approach 2:
The patent replaces the thermal mechanism of thermochromic inks with a mechanical erosion mechanism. Starch granules are embedded in the ink and removed by friction from erasers or abrasive surfaces, providing permanent erasability without temperature-induced color reversal.
2Stability of the object's composition
If polymer-encapsulated colorant with small particle size is used for erasability, then encapsulation stability is improved, but penetration into paper fibers increases and erasability decreases
Solution Approach 1:
Instead of using permanent polymer encapsulation, the patent employs temporary starch granule carriers that are easily removable. The starch granules serve as disposable carriers that facilitate ink deposition but are readily erased with common erasers, eliminating the erasability problem of encapsulated dyes.
3Ease of operation
If larger particles are used to prevent penetration and improve erasability, then mechanical removal is improved, but clogging of pen point occurs
Solution Approach 1:
The patent optimizes the particle size parameter of starch granules to a specific range (0.5-5 μm) that balances multiple requirements: large enough to prevent deep fiber penetration and enable erasability, but small enough to flow smoothly through ballpoint pen mechanisms without clogging.
4Illumination intensity
If dyes soluble in water are used for vivid color, then color intensity is improved, but UV resistance and color stability decrease
Solution Approach 1:
The patent creates a composite ink system combining water-soluble dyes (for vivid color) with starch granules (for UV resistance and erasability). The starch matrix protects the dye molecules from UV degradation while allowing vibrant color expression, and the composite structure enables mechanical erasability.
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 provides vivid, irreversible color on porous substrates with mechanical erasability, resistant to UV light, and stable dispersion without clogging, suitable for ball or roller pens.
Implementation Method 1
the core comprises an organic solvent immiscible with water and at least one dye soluble in said organic solvent
Implementation Method 2
the core-shell dye microparticles have a mean diameter D50 measured by dynamic light scattering
Implementation Method 3
the shell includes a resin component
Data Source
AI summary
The present invention concerns an erasable aqueous non-thermochromic writing ink comprising core-shell dye microparticles, wherein the core of said core-shell dye microparticles comprises an organic solvent immiscible with water and at least one dye soluble in said organic solvent and the shell includes a resin component. It concerns also a writing instrument containing it, the process of preparation of this ink and the use of the core-shell dye microparticles as the only coloring agent in the ink.