Aqueous Ink Microcapsule Pigment Dispersion Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aqueous ink compositions for writing instruments using microcapsule pigments with high specific gravity or poor dispersibility, such as titanium oxide or carbon black, tend to aggregate and clog, disrupting ink flow stability.
Innovation Solution
Incorporating a fatty acid polyol ester with a melting point between 40°C and 70°C, encapsulated within a urethane, urea, or urea-urethane shell, to improve dispersibility and control particle diameter, thereby preventing pigment aggregation and clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If microcapsule pigment is used to improve dispersibility of high specific gravity pigment, then dispersibility is improved, but aggregation and clogging occur around the ball
Solution Approach 1:
The invention changes the physical and chemical parameters of the microcapsule structure by controlling the shell thickness, shell material composition, and internal medium properties. These parameter changes optimize the balance between dispersibility improvement and prevention of aggregation, resolving the contradiction between enhanced dispersibility and ink flow stability.
Solution Approach 2:
The invention uses composite material structure consisting of a shell layer and an internal medium, where the shell is formed from specific polymers and the internal medium contains pigment particles dispersed in a carrier liquid. This composite structure allows the microcapsule to provide both improved dispersibility and prevent aggregation, simultaneously addressing both requirements.
2Stability of the object's composition
If microcapsule pigment with high specific gravity pigment is used, then pigment dispersibility is improved, but clogging due to aggregation occurs
Solution Approach 1:
The microcapsule acts as an intermediary structure that encapsulates the high specific gravity pigment particles, preventing them from directly aggregating. The shell layer and internal medium serve as a mediator between the pigment particles and the ink vehicle, maintaining dispersion stability and preventing clogging while still improving overall pigment dispersibility.
Solution Approach 2:
The invention employs flexible shell structures made from polymer materials that can deform and adapt to mechanical stress. This flexibility allows the microcapsules to withstand the forces encountered in the writing instrument without breaking, thereby preventing pigment release and clogging while maintaining dispersibility benefits.
Data Source
AI summary
Provided is an aqueous ink composition for a writing instrument with excellent stability of ink flow and the like, in which aggregation of a microcapsule pigment and clogging due to such aggregation are suppressed. The aqueous ink composition for a writing instrument includes a microcapsule pigment which includes inside, at least, a pigment and a medium of a fatty acid polyol ester. A melting point of the fatty acid polyol ester is preferably 40° C. or higher, and is preferably 70° C. or lower.