Hydroxy-functional Polyester Dispersion with Urethane Groups
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing aqueous polyester dispersions for paints and coatings often require high amounts of volatile organic solvents, leading to unsatisfactory application reliability, film optical properties, and resistance to water or solvents, while also being costly and complex to prepare.
Innovation Solution
Hydroxy-functional polyester dispersions containing urethane groups, composed of specific weight percentages of hydroxy-functional polyester, di- and/or tri- and/or mono-hydroxycarboxylic acid, polyisocyanate component, and other components, are synthesized using a process that minimizes solvent use and eliminates the need for external emulsifiers, stabilizers, or surface-active substances, resulting in stable, low-acid-number dispersions suitable for a wide range of crosslinker resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high amounts of volatile organic solvents are used in existing aqueous polyester dispersions, then application reliability and coating properties are improved, but environmental harm and economic cost increase
Solution Approach 1:
The patent changes the chemical composition parameters by introducing specific hydrophilicizing agents (sulfonated compounds, carboxymethylated compounds, and their salts) to replace volatile organic solvents. This allows the dispersion to maintain stability and application reliability without relying on large amounts of harmful solvents, thus resolving the contradiction between reliability and environmental harm.
Solution Approach 2:
The patent creates a simplified dispersion system that copies the essential stabilizing function of traditional solvent-based systems but uses environmentally friendly aqueous components instead. The hydrophilicizing agents replicate the solubilization and stabilization effects previously achieved only through organic solvents, enabling solvent-free or low-solvent formulations.
2Stability of the object's composition
If high fractions of carboxyl and carboxylate groups are used to disperse polyisocyanate, then stable dispersion is achieved, but film optical properties and flow characteristics deteriorate
Solution Approach 1:
The patent applies local quality by using different types of hydrophilicizing agents with specific functions: sulfonated compounds for electrostatic stabilization, carboxymethylated compounds for steric stabilization, and their salts for pH control. This localized functional differentiation allows stable dispersion without excessive carboxyl groups that would harm optical properties, resolving the contradiction between stability and film quality.
3Ease of operation
If relatively large amounts of organic solvents are used in 2-component polyurethane coating compositions, then room temperature curing is achieved, but storage stability and resistance properties deteriorate
Solution Approach 1:
The patent changes the curing mechanism parameters by using blocked isocyanate groups that require thermal activation (baking) instead of room temperature curing. This parameter change eliminates the need for large amounts of organic solvents and hydrophilicizing agents, thereby improving storage stability and resistance properties while maintaining ease of application through controlled curing conditions.
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 resulting dispersions exhibit improved application reliability, reduced crater susceptibility, balanced hardness/elasticity, and excellent storage stability, with clear, defect-free coatings that maintain optical and mechanical properties even after curing.
Implementation Method 1
hydroxy-functional polyester dispersions containing urethane groups... reaction products of 87.0% to 95% by weight of at least one hydroxy-functional polyester... and 4% to 10.6% by weight of one or more at least difunctional polyisocyanate component
Data Source
AI summary
The invention relates to new, aqueous, hydroxy-functional polyester dispersions containing urethane groups, to a process for preparing them, and to their use in combination with crosslinker resins for preparing paints, coatings and adhesives.