Polyurethane Dispersion Stability via Polyol Blend
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Solution Overview
Problem
Aqueous polyurethane dispersions often fail to produce films with desired property profiles due to instability and insufficient environmental friendliness, particularly in coatings and adhesives, where high elasticity and mechanical properties are required.
Innovation Solution
The use of novel aqueous polyurethane dispersions produced with at least two poly(tetramethylene glycol) polyether polyols of different average molar masses and two different polyisocyanate components, where the diol precursors have number-average molecular weights between 400 to 8000 g/mol, and the lower molar mass diol accounts for 10 to 80% of the higher molar mass diol, along with specific hydroxy-functional compounds and amino-functional compounds, to achieve stable and environmentally friendly dispersions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyester polyols with high proportion of ethylene glycol and/or diethylene glycol are used, then elasticity is improved, but hydrolysis stability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameter by replacing polyester polyols with poly(tetramethylene glycol) polyether polyols, which have different molecular structure and resistance to hydrolysis while maintaining the desired elasticity properties
Solution Approach 2:
The patent uses a composite approach by combining poly(tetramethylene glycol) polyether polyols with specific polyisocyanate components to create a polyurethane dispersion that achieves both high elasticity and hydrolysis stability through synergistic material combination
2Strength
If polycarbonate and polytetramethylene glycol are used, then elasticity is improved, but elongation is reduced
Solution Approach 1:
The patent optimizes the molecular weight parameters of the poly(tetramethylene glycol) polyether polyols, using a combination of different Mn values (400-8000 g/mol) to achieve both high elasticity and elongation exceeding 1000%
Solution Approach 2:
The patent applies local quality by using polyols with different molecular weights in specific proportions (lower Mn polyol at 10-80% of higher Mn polyol) to create different regions within the polymer structure that contribute differently to elasticity and elongation
3Strength
If conventional polyurethane dispersions are used, then mechanical properties are achieved, but environmental friendliness deteriorates
Solution Approach 1:
The patent changes the chemical composition by selecting specific polyisocyanate components (aromatic, cycloaliphatic, or aliphatic) that balance mechanical performance with environmental considerations, replacing less environmentally friendly components while maintaining film properties
Solution Approach 2:
The patent develops aqueous polyurethane dispersions that can be applied in thin layers (reducing material consumption) while achieving the desired mechanical properties, thereby reducing overall environmental impact through efficient resource use
4Strength
If suitable building blocks are used to achieve desired property profile, then film properties are improved, but dispersion stability deteriorates
Solution Approach 1:
The patent optimizes the molecular weight parameters of the polyol components (Mn between 400-8000 g/mol) and their proportion (lower Mn at 10-80% of higher Mn) to achieve the right balance between film-forming ability and dispersion stability
Solution Approach 2:
The patent uses a composite formulation combining poly(tetramethylene glycol) polyether polyols with specific polyisocyanate components that work synergistically to provide both excellent film properties and long-term dispersion stability
Data Source
AI summary
The present invention relates to novel aqueous polyurethane dispersions produced using at least two poly(tetramethylene glycol) polyether polyols with different average molar masses and at least two different polyisocyanate components.