Anionic Polyurethane Urea Textile Coating for Wet Adhesion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for coating sheet-form textile materials with polyurethane dispersions face challenges in achieving high wet adhesion due to the use of hydrophilic structural units, which lead to swelling and reduced adhesion, and are often costly and environmentally unfriendly.
Innovation Solution
An aqueous dispersion of anionically modified polyurethane urea, composed of aromatic diisocyanate, polyether polyol, isocyanate-reactive compounds with ionogenic groups, and polyamine, is applied to the textile material, providing a high content of urethane and urea groups for excellent adhesion while being environmentally harmless and cost-effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polyurethanes containing hydrophilic structural units are used in aqueous polyurethane dispersions, then the polyurethane becomes dispersible in water, but the hydrophilic structural units lead to swelling of the polyurethane in water and reduce adhesion
Solution Approach 1:
The patent extracts the harmful effect of hydrophilic structural units by using anionic modification through reaction with isocyanate groups and compounds containing ionogenic groups (such as carboxylic acids, sulfonic acids, or their salts). This creates water dispersibility through ionic groups attached to the polyurethane backbone rather than through traditional hydrophilic structural units, thereby avoiding swelling while maintaining adhesion.
Solution Approach 2:
The patent changes the chemical parameter of the polyurethane by introducing anionic groups through modification reactions. The anionic groups (carboxylate, sulfonate, etc.) provide water dispersibility without causing swelling, thus resolving the contradiction between dispersibility and adhesion strength.
2Strength
If polyurethanes are used as adhesive coat without hydrophilic structural units, then adhesion is maintained, but the use of organic solvents becomes necessary which is undesirable for economic and ecological reasons
Solution Approach 1:
The patent changes the chemical composition parameter by introducing anionic groups that enable water dispersibility. This allows the use of aqueous dispersions instead of organic solvent solutions, eliminating harmful solvent emissions while maintaining the adhesion properties needed for the adhesive coat.
3Strength
If silylated polyurethanes are used to improve wet adhesion, then self-crosslinking components compensate for swellability, but the components are cost-intensive and release VOCs which is ecologically undesirable
Solution Approach 1:
The patent extracts the problematic silyl groups and replaces them with anionic groups (carboxylate, sulfonate, etc.) that provide similar water dispersibility without requiring costly silylation steps or releasing VOCs. The anionic modification achieves the same goal of enabling aqueous dispersion without the harmful side effects.
Solution Approach 2:
The patent uses conventional, cost-effective anionic groups (from common acids like carboxylic or sulfonic acids) instead of expensive silylating agents. These anionic groups provide the necessary water dispersibility without requiring additional costly processing steps or releasing harmful VOCs.
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 achieves excellent wet adhesion and high strength in coated textile materials, suitable for various textile forms, including woven and nonwoven fabrics, with a flexible and non-tacky adhesive coat that is inexpensive to produce and environmentally friendly.
Implementation Method 1
aqueous dispersion of anionically modified polyurethane urea
Implementation Method 2
excellent wet adhesion and high strength in coated textile materials
Data Source
AI summary
The invention relates to a method for coating sheet-form textile materials, in which there is applied to a sheet-form textile material an aqueous dispersion containing anionically modified polyurethane ureas comprising (A) aromatic diisocyanate, (B) polyether polyol having a mean molecular weight greater than 1500, (C) at least one compound containing from 1 to 2 isocyanate-reactive groups and at least one ionogenic group, (D) polyamine having a mean molecular weight of at least 32, and (E) water, wherein the mean total functionality of the isocyanate-reactive compounds B to D is from 1.85 to 2.2, the molar ratio of the isocyanate groups of component A to the isocyanate-reactive groups of components B to D is greater than 1, and the polyurethane ureas have a content of from 800 to 1500 mmol of urethane groups/kg of anionically modified polyurethane urea and a content of from 800 to 1800 mmol of urethane plus urea groups/kg of anionically modified polyurethane urea.