Aqueous polyurethane resin dispersion
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Solution Overview
Problem
Current aqueous inkjet printing technologies face challenges with storage stability and physical properties of printed images, including adhesion, waterproofness, and solvent resistance, particularly with cationic polyurethane resins that have limited reactivity and require laborious synthesis methods.
Innovation Solution
Aqueous polyurethane resin dispersion incorporating a tertiary amino group or quaternary N-atom, polyalkylene oxide, and a polyester backbone, which enhances colloidal stability and physical properties through improved adhesion and scratch resistance, achieved by reacting a polyester polyol with a polyether diol and a polyisocyanate, and subsequently protonating the tertiary amino group to form a cationic resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a water-soluble cationic resin such as poly(diallyldimethylammonium chloride) is used to improve waterproof characteristics through electrostatic bonding, then waterproof characteristics are improved, but the resin itself is easily dissolved in water leading to insufficient waterproof effect and poor physical properties
Solution Approach 1:
The patent uses a copolymer consisting of a cationic polymer chain and a water-soluble polymer chain, creating a composite material that combines the electrostatic bonding capability of cationic resins with the water resistance and film-forming properties of water-soluble polymers. This composite structure allows the resin to maintain both its charge functionality and structural integrity in aqueous environments.
Solution Approach 2:
The patent modifies the molecular structure parameters of the resin by introducing specific functional groups and controlling the copolymer composition ratios. By adjusting the charge density, molecular weight, and composition of the copolymer, the resin achieves optimal balance between electrostatic bonding capability and water resistance, preventing dissolution while maintaining effective pigment fixation.
2Reliability
If conventional cationic polymers are used for pigment fixation, then electrostatic bonding is achieved, but the polymers do not crosslink or form films leading to poor adhesion and scratch resistance
Solution Approach 1:
The copolymer structure combines cationic polymer segments for electrostatic pigment fixation with water-soluble polymer segments that can form continuous films and provide mechanical strength. This composite material simultaneously achieves effective pigment bonding and forms a cohesive film matrix that provides adhesion and scratch resistance.
Solution Approach 2:
The water-soluble polymer chain acts as an intermediary that bridges the cationic binding sites and the substrate surface. It provides a film-forming matrix that adheres to the substrate while incorporating the cationically bound pigments, thereby transferring and distributing mechanical stress across the entire structure rather than concentrating it at the pigment-resin interface.
3Object-affected harmful factors
If aqueous pigment inks are used for environmental friendliness, then environmental load is reduced, but bleeding and ink coalescence occur due to insufficient adsorption into the ink-jet receiving layer
Solution Approach 1:
The copolymer resin combines cationic functional groups for strong electrostatic adsorption of anionic pigment particles with water-soluble polymer chains that provide film-forming capability and coalescence prevention. This composite structure enables effective pigment fixation in aqueous systems without requiring organic solvents.
Solution Approach 2:
The patent optimizes the charge density, molecular weight, and composition ratios of the copolymer to maximize pigment adsorption efficiency. By carefully controlling these parameters, the resin achieves sufficient adsorption strength to prevent bleeding and coalescence while maintaining the environmental benefits of aqueous formulation.
4Strength
If polyurethane resin is used to improve adhesion and scratch resistance, then physical properties are enhanced, but storage stability and colloidal stability are insufficient
Solution Approach 1:
The patent creates a composite polyurethane structure where polyurethane segments provide adhesion and mechanical strength, while incorporated ionic or polar groups provide colloidal stabilization in aqueous dispersion. This composite molecular architecture allows the resin to maintain both enhanced physical properties and improved storage stability.
Solution Approach 2:
The patent modifies the polyurethane molecular structure by introducing specific functional groups and controlling molecular weight distribution. These parameter changes enhance the resin's ability to form stable aqueous dispersions with controlled particle size and charge, improving both storage stability and colloidal stability while maintaining adhesion and scratch resistance.
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 solution provides improved storage stability, increased colloidal stability, and enhanced physical properties such as adhesion and scratch resistance, leading to better printing quality and image durability.
Implementation Method 1
Waterproof characteristics can be improved by fixing of the pigment of the aqueous ink due to the electrostatic bonding between an anionic group of the pigment in the ink and a cationic group of the water-soluble cationic resin.
Implementation Method 2
these polymers do not crosslink with each other nor form a film, leading to poor physical properties of the printed image
Data Source
AI summary
An aqueous polyurethane resin dispersion includes a cationic group and a polyalkylene oxide in a side chain thereof. The polyurethane resin is obtainable by reacting a polyester polyol, a polyether diol, a polyol containing a quaternary N-atom or tertiary amino group, and a polyisocyanate. The polyester polyol is obtained by reacting an aromatic polycarboxylic acid and a polyol. The polyurethane resin is suitable as a resin in treatment liquids of substrates and images made by inkjet printing.