Anionic Polyurethane Urea Textile Coatings With Strong Wet Adhesion
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Solution Overview
Problem
Existing polyurethane solutions used in textile coatings lack sufficient wet adhesion due to hydrophilic building blocks, leading to swelling and potential delamination, and are either costly or environmentally unfriendly, especially when using silylated or sulfone-functionalized polyurethanes.
Innovation Solution
An aqueous dispersion of anionically modified polyurethane ureas, composed of aromatic diisocyanate, polyether polyol, isocyanate-reactive compounds with ionic groups, and polyamine, with specific molecular weight and functionality ratios, is applied to textile fabrics to achieve high wet adhesion and environmental sustainability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polyurethanes with hydrophilic building blocks are used in aqueous dispersions, then dispersibility in water is improved, but wet adhesion deteriorates due to swelling
Solution Approach 1:
The patent applies local quality by creating distinct regions within the polyurethane molecule: hydrophilic ionic groups (carboxylate, sulfonate, phosphate) are localized at the periphery to ensure water dispersibility, while the core polyurethane structure remains hydrophobic to maintain adhesion. This spatial separation of properties allows the polymer to simultaneously achieve dispersibility and bonding capability without the swelling problems of fully hydrophilic structures
Solution Approach 2:
The invention creates a composite polyurethane structure combining ionic hydrophilic segments (from compounds like dimethylolpropionic acid, dimethyloldihydroxyethylene sulfonic acid, or phosphonic acid derivatives) with traditional polyurethane chains. This composite architecture integrates the water-dispersing capability of ionic groups with the adhesive properties of polyurethane, achieving both required functions in a single material system
2Reliability
If silylated polyurethanes are used to improve wet adhesion through self-crosslinking, then wet adhesion is improved, but cost increases and VOC emissions occur
Solution Approach 1:
The patent replaces expensive silylated polyurethanes with a more economical ionic polyurethane system that achieves adequate wet adhesion through ionic interactions and hydrogen bonding rather than covalent crosslinking. The ionic groups provide sufficient bonding capability without requiring the complex silyl chemistry, resulting in lower material costs and elimination of VOC-emitting crosslinking reactions
Solution Approach 2:
The invention changes the chemical parameters of the polyurethane from silyl-functionalized groups to ionic groups (carboxylate, sulfonate, phosphate). This parameter change fundamentally alters the crosslinking mechanism from covalent Si-O-Si bonds to ionic and hydrogen bonding interactions, eliminating VOC emissions while maintaining practical wet adhesion performance for textile applications
3Reliability
If polyurethane solutions without hydrophilic building blocks are used, then wet adhesion is improved, but environmental friendliness deteriorates due to organic solvent use
Solution Approach 1:
The patent fundamentally changes the solvent system parameter from organic solvents to water by incorporating ionic hydrophilic groups into the polyurethane structure. This parameter change enables the polymer to form stable aqueous dispersions through ion-dipole interactions with water molecules, replacing harmful organic solvents with environmentally benign water while maintaining the polyurethane's adhesive properties
Solution Approach 2:
The invention creates a composite structure combining hydrophobic polyurethane chains with hydrophilic ionic segments. This composite architecture allows the material to interface with both the textile substrate (through hydrophobic polyurethane bonding) and the aqueous dispersion medium (through hydrophilic ionic groups), enabling solvent-free water-based application
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 method provides textile fabrics with excellent wet adhesion, high strength, and cost-effectiveness while being environmentally friendly, suitable for various textile types, including woven, nonwoven, and knitted goods, and is particularly effective in laminate production.
Implementation Method 1
an aqueous dispersion containing anionically modified polyurethane ureas
Implementation Method 2
aqueous polyurethane dispersions are now increasingly being used to reduce solvent emissions
Implementation Method 3
The method provides textile fabrics with excellent wet adhesion, high strength
Data Source
AI summary
The invention relates to a method for coating textile web material, wherein an aqueous dispersion comprising anionically modified polyurethane ureas made of A. aromatic diisocyanate, B. polyether polyol having an average molecular weight greater than 1500, C. at least one compound comprising 1 to 2 isocyanate reactive groups and at least one ionogenic group, D. polyamine having an average molecular weight of at least 32, and E. water, wherein the average overall functionality of the isocyanate reactive compounds B through D is 1.85 to 2.2, the molar ratio of the isocyanate groups of component A to the isocyanate reactive groups of components B through D is greater than 1, and the polyurethane ureas have a content of 800 to 1500 mmol urethane groups/kg of anionically modified polyurethane urea and a content of 800 to 1800 mmol of urethane plus urea groups/kg of anionically modified polyurethane urea, is applied to a textile web material.