Aqueous Ink Composition for Bleed-Resistant Writing Lines
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Solution Overview
Problem
Aqueous ink compositions for writing instruments using resin particles colored with dyes suffer from bleeding of drawn lines over time, despite achieving excellent writing performance.
Innovation Solution
An aqueous ink composition containing an aqueous dispersion of colored resin fine particles with cyclohexyl (meth)acrylate monomer content of 30 mass % or greater, basic or oil-soluble dye, and terpene phenol resin, with a specific resin ratio and particle size, to prevent bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resin particles colored with dye are used in aqueous ink composition, then writing performance is improved, but bleeding of drawn lines occurs over time
Solution Approach 1:
The patent changes the chemical composition parameters of the resin particles by incorporating specific monomers (styrene 5-30 mass%, (meth)acrylic acid 5-30 mass%, N-vinylpyrrolidone 5-30 mass%) and controlling the dye content (15-50 mass% relative to polymer component). These parameter adjustments optimize both writing performance and prevent bleeding over time.
Solution Approach 2:
The patent creates composite resin particles combining multiple polymer components (styrene, (meth)acrylic acid, N-vinylpyrrolidone) with dye molecules. This composite structure provides both the writing performance needed and the stability to prevent bleeding, as the multi-component resin matrix better anchors the dye compared to single-component resins.
2Illumination intensity
If basic dye or oil-soluble dye is used to color resin particles, then color development is enhanced, but dye transfer to paper occurs causing bleeding
Solution Approach 1:
The resin particle acts as an intermediary carrier between the dye and the writing surface. The specifically designed resin matrix with multiple functional groups (carboxyl from (meth)acrylic acid, amide from N-vinylpyrrolidone, and aromatic rings from styrene) provides strong interaction sites that anchor the basic or oil-soluble dyes, preventing their transfer to paper while maintaining color development.
Solution Approach 2:
The patent optimizes the dye content parameter (15-50 mass% relative to polymer component) and the resin composition parameters to achieve the right balance between color intensity and dye retention. The specific monomer ratios create a resin matrix with optimal binding affinity for the dyes.
Data Source
AI summary
An aqueous ink composition for writing instruments containing an aqueous dispersion of colored resin fine particles, the colored resin fine particles containing at least a cyclohexyl (meth)acrylate monomer and a basic dye or an oil-soluble dye, the cyclohexyl (meth)acrylate monomer being contained in an amount of 30 mass % or greater relative to an amount of a polymerizable polymer component in the colored resin fine particles, and the colored resin fine particles further containing a terpene phenol resin.