Aqueous Ink Ball Point Pen Viscosity Control via Shear-Thinning
Solution Overview
Problem
Conventional aqueous ink ball point pen compositions suffer from feathering, striking through, starving, blobbing, and splitting, which hinder smooth writing and fine letter formation.
Innovation Solution
Incorporating modified polyvinyl alcohol and boric acid or its salts as viscosity controlling agents in the ink composition to prevent these issues, with specific concentration ranges to maintain optimal viscosity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If low viscosity aqueous ink is used, then smooth writing feeling is achieved, but feathering occurs on written lines
Solution Approach 1:
The patent changes the viscosity parameter by introducing shear-thinning behavior through xanthan gum, allowing the ink to have low viscosity during writing (smooth feel) but high viscosity when stationary (prevents feathering). This dynamic viscosity adjustment resolves the contradiction between writing smoothness and feathering prevention.
Solution Approach 2:
The patent combines xanthan gum (viscosity controlling agent) with specific surfactants and pigments to create a composite ink formulation. The xanthan gum provides shear-thinning properties while the surfactants control surface tension, working together to prevent feathering while maintaining smooth writing characteristics.
2Object-affected harmful factors
If viscosity controlling agent is added to prevent feathering, then feathering is improved, but splitting and blobbing occur
Solution Approach 1:
The patent optimizes the concentration of xanthan gum within a specific range (0.01-5% by mass) to achieve the right balance of viscosity control. This parameter optimization ensures sufficient shear-thinning effect for feathering prevention while avoiding excessive viscosity that would cause splitting and blobbing.
Solution Approach 2:
The patent introduces surfactants as intermediary substances that mediate between the viscosity controlling agent and the ink components. The surfactants adjust surface tension and improve wetting properties, preventing the ink from breaking into droplets (blobbing) or splitting while maintaining the shear-thinning effect for feathering prevention.
3Object-affected harmful factors
If viscosity controlling agent is added, then feathering is reduced, but ink followability decreases
Solution Approach 1:
The patent utilizes the dynamic shear-thinning property of xanthan gum, where the ink viscosity automatically adjusts based on the applied shear rate. During writing (high shear rate), viscosity is low for good followability; when stationary (low shear rate), viscosity is high for feathering prevention. This dynamic behavior resolves the contradiction between followability and feathering control.
Solution Approach 2:
The patent carefully controls the concentration and molecular weight of xanthan gum to optimize the shear-thinning curve, ensuring that the viscosity at writing speeds remains low enough for good ink followability while providing sufficient viscosity at rest to prevent feathering.
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 composition effectively prevents feathering, striking through, starving, and splitting, enabling smooth writing and fine letter formation without compromising writing feel or ink stability.
Implementation Method 1
Incorporating modified polyvinyl alcohol and boric acid or its salts as viscosity controlling agents in the ink composition to prevent these issues
Data Source
AI summary
Provided are an ink composition for an aqueous ink ball point pen, which contains modified polyvinyl alcohol and at least one selected from boric acid and salts thereof, and an aqueous ink ball point pen charged with the ink composition, wherein the boric acid and the salts thereof are preferably at least one selected from boric acid, alkali metal salts of boric acid and ammonium salts of boric acid.