Hydrophobically Modified Polyurethane Rheology Modifier
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Solution Overview
Problem
Commercially available hydrophobically modified ethylene oxide urethane (HEUR) polymers, such as ACRYSOL(TM) 5000 and ACRYSOL(TM) 6000, have a limited ICI/KU viscosity ratio, restricting the formulation's ability to add KU building rheology modifiers without increasing KU viscosity.
Innovation Solution
A composition of linear and branched hydrophobically modified alkylene oxide polyurethane polymers with molecular weights between 50,000 to 150,000 Daltons and polydispersity of 2.5 to 5.0, prepared through a multi-step process involving a stoichiometric excess of polyalkylene glycol, polyisocyanate branching agents, and difunctional linking agents, to achieve improved ICI/KU viscosity balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If commercially available HEUR polymers (ACRYSOL 5000 and 6000) are used, then ICI viscosity is improved, but KU viscosity increases concomitantly, limiting the formulator's ability to add KU building rheology modifiers
Solution Approach 1:
The patent applies parameter changes by controlling the polydispersity index (PDI) to be greater than 2.5 and adjusting the molecular weight (Mw) to specific ranges (50,000-150,000 Daltons). This selective parameter modification allows the polymer to provide enhanced ICI viscosity while maintaining lower KU viscosity compared to conventional HEUR polymers, thereby resolving the contradiction between high-shear and low-shear viscosity requirements
Solution Approach 2:
The invention creates a composite polymer structure combining linear and branched hydrophobically modified alkylene oxide polyurethane polymers with specific polydispersity characteristics. This composite approach enables the material to exhibit dual functionality: strong associative thickening at high shear rates (improving ICI viscosity) while maintaining acceptable low-shear viscosity (controlling KU viscosity), thus resolving the viscosity balance contradiction
2Ease of manufacture
If a standard 1-pot process is used to prepare HEUR polymers, then manufacturing simplicity is maintained, but the ICI/KU viscosity ratio is limited
Solution Approach 1:
The patent modifies the polydispersity parameter (PDI > 2.5) and molecular weight parameters during polymerization to achieve superior ICI/KU viscosity ratios. By controlling these parameters through the described multi-step process involving stoichiometric excess of polyalkylene glycol and controlled addition of isocyanates, the invention achieves enhanced high-shear viscosity performance while maintaining manufacturing feasibility, thus resolving the contradiction between ease of manufacture and viscosity ratio performance
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 multi-step process results in superior KU and ICI viscosities compared to single-pot reactions, enhancing the ICI/KU viscosity ratio, allowing for more efficient rheology modification in waterborne coatings without increasing KU viscosity.
Implementation Method 1
preparation of linear as well as branched HEUR polymers in separate examples... reacting a polyglycol, a hydrophobic alcohol, a diisocyanate, and a triisocyanate together in a one-pot reaction
Implementation Method 2
hydrophobically modified ethylene oxide urethane (HEUR) polymers... urethane groups that link the polyalkylene oxide groups
Data Source
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AI summary
The present invention relates to a composition comprising a hydrophobically modified alkylene oxide polyurethane characterized by having a Mw of from 50,000 to about 150,000 Daltons and a polydispersity of 2.5 to about 5.0. The present invention further relates to a multi-step process for the preparation of the hydrophobically modified polymer.