Silylated Polyurethane Viscosity Reduction via Isocyanate Composition
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Solution Overview
Problem
Silylated polyurethanes typically have high viscosity due to hydrogen bonding from urea and urethane groups, making them difficult to process, and existing methods to reduce this viscosity either require costly additional steps, use toxic materials, or are not fully effective.
Innovation Solution
Using isocyanate comprising 2,4′-methylene diphenyl diisocyanate in limited amounts (less than 50% by weight) during the preparation of silylated polyurethanes to minimize chain extension and suppress unwanted secondary reactions, resulting in polyurethanes with lower viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional isocyanates are used to prepare silylated polyurethanes, then the polyurethane exhibits high viscosity due to hydrogen bonding from urea and urethane groups, but this high viscosity makes the material difficult to process
Solution Approach 1:
The patent changes the chemical composition parameter of the isocyanate by limiting 2,4'-methylene diphenyl diisocyanate to less than 50% by weight, which reduces hydrogen bonding density and thereby reduces viscosity to improve processability
Solution Approach 2:
The patent eliminates the need for expensive additional synthetic steps (such as allophanatization or biuretization) by using a simplified isocyanate composition, reducing production complexity and cost
2Object-affected harmful factors
If long chain-polyether polyols with high functionality are used to decrease urethane content, then hydrogen bond density is reduced, but the method requires polyols with specific high functionality and low unsaturation which limits material selection
Solution Approach 1:
The patent changes the isocyanate composition parameter rather than requiring specific polyol parameters, allowing broader polyol selection while still achieving reduced hydrogen bonding through the controlled isocyanate mixture
3Object-affected harmful factors
If isocyanate comprising 2,4′-methylene diphenyl diisocyanate is used in limited amounts (less than 50% by weight), then chain extension is minimized and secondary reactions are suppressed, but this requires precise control of isocyanate composition
Solution Approach 1:
The patent specifies a clear compositional parameter (less than 50% by weight of 2,4'-methylene diphenyl diisocyanate) that balances chain extension control with manufacturing feasibility, avoiding overly strict requirements
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 approach effectively reduces the viscosity of silylated polyurethanes without the need for additional synthetic steps or toxic materials, improving processability and reducing production costs.
Implementation Method 1
contacting at least one isocyanate with at least one isocyanate-reactive compound and with at least one aminosilane
Implementation Method 2
This high viscosity can be related to hydrogen bonding due to the presence of urea and urethane groups
Data Source
AI summary
The present invention relates to a silylated polyurethane obtainable by a process comprising the step of contacting at least one isocyanate with at least one isocyanate-reactive compound and with at least one aminosilane; wherein said at least one isocyanate comprises 2,4′-methylene diphenyl diisocyanate, and wherein said at least one isocyanate comprises less than 50.0% by weight of said 2,4′-methylene diphenyl diisocyanate based on the total weight of said at least one isocyanate. The present invention also relates to a process for preparing said silylated polyurethane. The present invention also relates to formulations and compositions comprising said silylated polyurethane, and the use thereof for the preparation of adhesives, coatings, sealants, elastomers, or foams.