Multi-Core Writing Implement Ink Design to Prevent Erasure Smearing
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Solution Overview
Problem
Conventional multi-core writing implements face issues with thermochromic handwriting smearing when erased with a friction member, causing unwanted color transfer from non-thermochromic ink onto the writing surface.
Innovation Solution
A multi-core writing implement with a retractable mechanism that houses both thermochromic and non-thermochromic writing bodies, utilizing an oil-based non-thermochromic ink composition with specific pigment properties and a friction member to minimize smearing during decoloration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-core writing implement contains both thermochromic and non-thermochromic writing bodies, then the user can make both thermochromic and non-thermochromic handwriting with a single implement, but the non-thermochromic colorant smears onto the writing surface when the thermochromic handwriting is erased with a friction member
Solution Approach 1:
The patent changes the chemical parameters of the non-thermochromic ink composition by specifying it as an oil-based ink containing pigment rather than dye, with particular attention to viscosity and composition. This parameter change makes the non-thermochromic ink resistant to smearing during frictional erasure of thermochromic handwriting, while still allowing proximal writing without mutual interference.
2Illumination intensity
If the non-thermochromic ink composition uses dye instead of pigment, then the ink provides good color intensity, but the colorant is easily adsorbed onto the friction member and trails during frictional force
Solution Approach 1:
The patent changes the fundamental parameter of the colorant from dye to pigment in the non-thermochromic ink composition. This parameter change fundamentally alters the behavior of the colorant during frictional erasure, as pigment particles are not easily adsorbed onto the friction member like dye molecules are, thereby preventing smearing and trailing while maintaining color intensity.
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
Enables the proximal use of thermochromic and non-thermochromic handwriting without smearing, making it suitable for preparing official documents with clear, non-thermochromic ink after decoloring thermochromic ink.
Implementation Method 1
a reversibly thermochromic ink composition
Implementation Method 2
a friction member is provided at the other end in the lengthwise direction of the shaft cylinder
Data Source
Figure 1~2
AI summary
A multi-core writing implement (1) in which a plurality of writing bodies (2) is stored inside a shaft cylinder (9), the multi-core writing implement including a retractable mechanism that selectively protrudes and retracts one of the writing bodies (2) through a front-end opening (9H) provided at one end in a lengthwise direction of the shaft cylinder (9), the writing bodies (2) including at least one thermochromic writing body (2A) in which a reversibly thermochromic ink composition is stored and at least one non-thermochromic writing body (2C) in which a non-thermochromic ink composition is stored, the non-thermochromic ink composition being an oil-based ink composition that includes a pigment, a friction member (10) being provided at the other end in the lengthwise direction of the shaft cylinder (9).