Water-Based Ink Triblock Copolymer Rubbing Resistance
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Solution Overview
Problem
Water-based pigment inks for ink-jet recording face challenges with rubbing resistance on glossy paper and unevenness on regular paper, particularly when polymers are added in excess, affecting viscosity and maintenance performance.
Innovation Solution
A water-based ink formulation incorporating a pigment, oligoethylene glycol monoalkyl ether, and a water-soluble ABA-type triblock copolymer with specific molecular weight and acid value ranges, which enhances rubbing resistance by improving film-forming properties and solubility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polymer is added to the water-based pigment ink in an excessive amount to improve rubbing resistance, then the rubbing resistance is improved, but the viscosity of the ink increases affecting maintenance performance
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer from conventional types to a specific copolymer containing hydrophobic groups (styrene, methyl styrene, p-methoxystyrene) with controlled composition ratios. This structural parameter change enables achieving high rubbing resistance without the viscosity increase that would result from simply increasing polymer quantity, thereby resolving the contradiction between rubbing resistance and viscosity stability.
Solution Approach 2:
The patent uses a composite polymer structure combining hydrophilic blocks (polymer blocks A) and hydrophobic blocks (polymer block B) in an ABA-type triblock configuration. This composite material approach allows the hydrophobic portions to enhance rubbing resistance through strong interaction with pigment particles, while the hydrophilic portions maintain ink solubility and prevent excessive viscosity increase, thus resolving the contradiction between rubbing resistance and viscosity.
2Strength
If a polymer is added to the water-based pigment ink to improve rubbing resistance, then the rubbing resistance is improved, but unevenness occurs in recording on regular paper
Solution Approach 1:
The patent optimizes the compositional parameters of the copolymer, specifically controlling the content of hydrophobic groups to be 5-50 mol% and the weight average molecular weight to be 3,000-30,000. These parameter optimizations ensure sufficient rubbing resistance while preventing the ink from causing unevenness on regular paper, thereby resolving the contradiction between rubbing resistance and recording uniformity.
Solution Approach 2:
The patent introduces local hydrophobic character into specific regions of the polymer molecule (polymer block B) while maintaining overall hydrophilicity (polymer blocks A). This local quality differentiation allows the hydrophobic segments to provide rubbing resistance at the pigment-polymer interface, while the hydrophilic segments ensure uniform distribution and prevent unevenness on regular paper, thus resolving the contradiction.
3Strength
If a polymer is added to the water-based pigment ink to improve rubbing resistance, then the rubbing resistance is improved, but the ink is more likely to cause unevenness in recording on regular paper
Solution Approach 1:
The patent precisely controls the chemical composition parameters including the mol% of hydrophobic groups (5-50%), the weight average molecular weight (3,000-30,000), and the acid value (90-200 mgKOH/g). These parameter specifications ensure consistent performance across different recording conditions, achieving reliable rubbing resistance without compromising recording consistency on regular paper.
Solution Approach 2:
The ABA-type triblock copolymer structure creates a balanced composite material where hydrophilic blocks A provide water solubility and uniform distribution, while the central hydrophobic block B provides rubbing resistance. This composite structure ensures reliable and consistent recording quality across different paper types, resolving the contradiction between rubbing resistance and recording consistency.
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 achieves good rubbing resistance on glossy paper and reduces unevenness on regular paper while maintaining optimal viscosity and re-dispersion properties.
Implementation Method 1
which has a weight average molecular weight of 3,000 to 30,000; which has an acid value of 90 mgKOH/g to 200 mgKOH/g; and which is partially or completely neutralized
Implementation Method 2
oligoethylene glycol monoalkyl ether
Data Source
Figure 1A~2B
Figure 3
AI summary
A water-based ink for ink-jet recording includes: a pigment; water; oligoethylene glycol monoalkyl ether; and a water-soluble resin. The water-soluble resin is an ABA-type triblock copolymer which has a polymer block A composed only of methyl methacrylate and methacrylic acid and a polymer block B composed only of benzyl methacrylate and methacrylic acid; which has a weight average molecular weight of 3,000 to 30,000; which has an acid value of 90 mgKOH/g to 200 mgKOH/g; and which is partially or completely neutralized.