High-Laydown Writing Tool With Stable Pigment Dispersion
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Solution Overview
Problem
Existing non-aqueous ball pen inks face issues with pigment settlement during storage and drying due to poor stabilization in non-aqueous systems, leading to formulation difficulties and poor writing performance, while dye-based inks lack chemical and light resistance.
Innovation Solution
A non-aqueous writing ink formulation comprising 5-25% pigment, 5-35% resin, and a gelling agent of silica particles and fatty acid amide wax or water-insoluble cellulose nanofibers, with a viscosity range of 15,000 to 150,000 cps at rest and 1,200 to 10,000 cps under shear, and a pigment size of 80-700 nm, ensuring stable dispersion and high laydown without smearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pigments are used in non-aqueous ink, then chemical and light resistance is improved, but pigment settlement during storage occurs
Solution Approach 1:
The patent introduces an intermediary substance (resin or polymer) that coats the pigment particles, creating a stable interface between the hydrophobic pigment and the non-aqueous solvent. This intermediary layer prevents direct contact between pigment particles and the solvent, eliminating the settlement issue while preserving the chemical and light resistance benefits of pigments.
Solution Approach 2:
The patent creates a composite ink formulation by combining pigments with resins or polymers in a non-aqueous solvent system. This composite approach allows the ink to simultaneously exhibit the durability of pigments and the stability required for non-aqueous storage, resolving the contradiction between pigment benefits and storage stability.
2Reliability
If non-aqueous solvent is used, then drying issues are reduced, but pigment stabilization becomes difficult
Solution Approach 1:
The patent changes the chemical parameters of the ink formulation by selecting specific non-aqueous solvents with appropriate polarity and viscosity characteristics. This parameter optimization allows the ink to maintain pigment stability without the drying issues associated with water-based formulations, making the formulation process more straightforward.
3Illumination intensity
If high pigment concentration is used, then color vividness is improved, but ink viscosity increases causing dispensing issues
Solution Approach 1:
The patent optimizes the viscosity parameter of the ink formulation by adjusting solvent composition and adding viscosity modifiers. This allows the ink to maintain high pigment concentration for vivid color while ensuring the viscosity remains within the optimal range for smooth dispensing from the writing instrument.
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 provides vivid and intense color with reduced pigment settlement and drying issues, maintaining viscosity and particle size stability for smooth writing over time, reducing clogging and smearing.
Implementation Method 1
In steric stabilization, the pigment can be sterically stabilized when the surface of the solid particles is covered by polymers, making particle-to-particle contact difficult.
Implementation Method 2
the writing ink has a viscosity at rest at about 20° C. of between about 15 000 cps and about 150 000 cps and a viscosity under shear at about 100 s−1 at about 20° C. of between about between about 1200 cps and about 10000 cps
Implementation Method 3
a non-aqueous writing ink which comprises... about 5 to about 25 wt.-%, of at least one pigment... wherein the pigment has a D50 particle size of between about 80 nm and about 700 nm
Data Source
AI summary
A handheld writing instrument which dispenses a non-aqueous pigment-based writing ink. Being based on a non-aqueous writing ink, the writing instrument is less subject to issues of ink drying due to solvent evaporation, such as build-up of dried ink on the writing ink and smearing caused by dried ink agglomerations. Due to its high-laydown characteristics, the writing instrument provides a vivid intense color impression despite the use of pigments as coloring agents.