Erasable Ink Composition With Adjustable Color Erasing Time
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Solution Overview
Problem
Existing erasable inks lack control over the time it takes for the color to be erased.
Innovation Solution
An erasable ink set comprising an erasable ink with a pH indicator and an erasing time adjuster, which includes water and a water-soluble organic solvent or surfactant, allows for controlling the erasing time by adjusting the application of the erasing time adjuster on the recording medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an erasable ink using a pH indicator is used, then the ink can be erased by changing from alkaline to neutral state, but the time until the color is erased cannot be controlled
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the ink system. Specifically, it adjusts the pH indicator concentration (0.1-3.0 wt%), alkali metal hydroxide concentration (0.1-5.0 wt%), water-soluble organic solvent content (5-50 wt%), and surfactant concentration (0.1-5.0 wt%) to precisely control the erasing time. This allows the erasing time to be adjusted within a specific range (3 hours to 7 days) while maintaining the erasability function.
Solution Approach 2:
The patent introduces an intermediary mechanism by adding a water-soluble organic solvent and/or surfactant that mediates between the pH indicator and the environment. These intermediaries control the rate at which the pH indicator responds to neutralization, thereby controlling the erasing time without affecting the fundamental erasability mechanism.
2Stability of the object's composition
If conventional ink formulations are used, then color stability is maintained, but the ability to control erasing time is lost
Solution Approach 1:
The patent creates a composite ink formulation by combining multiple components with specific functions: pH indicator (for color change), alkali metal hydroxide (for alkaline state), water-soluble organic solvent (for controlling dissolution rate), and surfactant (for enhancing solubility and controlling interface). This composite structure enables both color stability during storage and controlled erasing time when neutralized.
Solution Approach 2:
The patent systematically adjusts composition parameters to achieve the desired balance between stability and erasability. The pH indicator concentration (0.1-3.0 wt%), alkali metal hydroxide concentration (0.1-5.0 wt%), water-soluble organic solvent content (5-50 wt%), and surfactant concentration (0.1-5.0 wt%) are optimized to ensure color stability while enabling controlled erasing within 3 hours to 7 days.
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 erasing time of the erasable ink can be precisely controlled, ranging from under 3 hours to over 7 days, depending on the application of the erasing time adjuster, enhancing the flexibility and effectiveness of the ink's erasing process.
Implementation Method 1
an erasable ink using a pH indicator which develops color in an alkaline state, for example, with phenolphthalein or the like, and erases color in a neutral state
Data Source
Figure 1
AI summary
An erasable ink set includes: an erasable ink; and an erasing time adjuster that adjusts an erasing time of the erasable ink, wherein the erasable ink includes a color developing agent, water, and at least one of a first water-soluble organic solvent or a first surfactant, the color developing agent includes a pH indicator, and the erasing time adjuster includes water and at least one of a second water-soluble organic solvent or a second surfactant.