Water-Emulsifiable Polyurethane Acrylates Storage Stability
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Solution Overview
Problem
Water-dispersible urethane acrylates tend to separate during storage or when mixed with other dispersions, leading to stability issues in coating compositions.
Innovation Solution
The development of radiation-curable urethane(meth)acrylates comprising specific components such as isocyanates, polyalkylene oxide polyethers, hydroxy-functional (meth)acrylates, and compounds with acid or basic groups, which are prepared through a specific process to enhance stability in aqueous dispersion across various dilution, temperature, and pH ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If water-dispersible urethane acrylates are prepared using known processes with ionic sites, then water dispersibility is achieved, but storage stability deteriorates causing separation during storage
Solution Approach 1:
The invention changes the chemical parameters by using nonionic hydrophilic groups (polyethylene oxide and polypropylene oxide units) instead of ionic sites, and by incorporating internal salt groups formed from the reaction of isocyanate with compounds containing both isocyanate-reactive groups and acid functions. This parameter change maintains water dispersibility while eliminating the storage stability problems associated with ionic dispersions
Solution Approach 2:
The invention creates a composite molecular structure combining hydrophilic polyether chains (providing water dispersibility) with internal salt groups (providing structural stability). The urethane acrylate comprises both polyethylene oxide and polypropylene oxide units along with internal salt groups, creating a composite material that simultaneously achieves dispersibility and storage stability
2Ease of operation
If polyethylene oxide chains are used to provide water solubility, then water dispersibility is improved, but storage stability deteriorates leading to separation when diluted or mixed
Solution Approach 1:
The invention modifies the polyether chain composition by incorporating both polyethylene oxide and polypropylene oxide units in specific ratios. This compositional parameter change enhances the steric stabilization and prevents phase separation while maintaining water dispersibility, resolving the contradiction between dispersibility and storage stability
Solution Approach 2:
The invention creates a composite polyether structure combining different oxide units (ethylene and propylene) to achieve synergistic effects. The mixed polyether chain provides both hydrophilicity for water dispersibility and structural complexity for enhanced storage stability, preventing separation during storage, dilution, or mixing
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 urethane(meth)acrylates exhibit improved storage stability and maintain adhesion properties on substrates, making them suitable for use as adhesion primers, particularly for wood and wood-containing substrates.
Implementation Method 1
The hydrophilicity of such urethane(meth)acrylates is based on the water solubility of the polyethylene glycol chain. This imparts water solubility to the urethane(meth)acrylate.
Implementation Method 2
the water solubility can be increased by incorporating monomers each having acid or base functions into the polymer, as a result of which an internal salt is formed, which results in elevated water solubility
Implementation Method 3
A disadvantage in the use of water-dispersible urethane acrylates is that the aqueous dispersions separate in the course of storage, especially when diluted or mixed with other dispersions.
Data Source
AI summary
The present invention relates to storage-stable water-emulsifiable polyurethane acrylates, to a process for preparation thereof and to the use thereof.