Amide-Functionalized Silanes for Low Viscosity Polyurethane Adhesives

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Solution Overview

Problem

Silane-modified polymers face issues with high viscosity and low thermal stability due to urea linkages, which restrict processability and safety, especially when used in adhesives and sealants, and require coupling agents that overcome these drawbacks.

Innovation Solution

The introduction of amide-functionalized silanes with a specific formula, which can be used as additives or endcapping agents in polyurethane systems, reduces viscosity and improves mechanical properties of the cured compositions, allowing for better handling and processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If aminoalkoxysilanes are used as endcapping agents, then adhesion and stability are improved, but viscosity increases significantly

Engineering Contradiction:

ImproveadhesionVSAvoidviscosity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the chemical structure parameter of the endcapping agent from amino group to amide group, which fundamentally alters the intermolecular interaction characteristics. This structural modification reduces hydrogen bonding strength while maintaining adhesion properties, thereby resolving the viscosity issue without sacrificing reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a simple amide functional group instead of complex aminoalkoxysilane structures, effectively replacing a problematic component with a simpler alternative that achieves the same adhesion function without the harmful side effects of high viscosity

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If aminoalkoxysilanes are used as endcapping agents, then adhesion is improved, but processability deteriorates due to high viscosity

Engineering Contradiction:

ImproveadhesionVSAvoidprocessability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent modifies the chemical parameter of the endcapping agent from primary amine to amide functional group. This change reduces the strength of intermolecular hydrogen bonds, thereby lowering viscosity and improving processability while preserving the adhesion-enhancing properties of silane-modified polymers

Inventive Principle:

Principle #35Parameter changes

3Speed

If primary amine-functionalized alkoxysilanes are used, then reactivity is improved, but safety and handling difficulty increase due to exothermic reactions

Engineering Contradiction:

Improvereaction rateVSAvoidexothermic reaction

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent converts the overly reactive amino group into a less reactive amide group, which eliminates the harmful exothermic reaction issue while still providing sufficient reactivity for the intended application. The amide group maintains the ability to form stable urea linkages without the dangerous side reactions characteristic of primary amines

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The amide functional group acts as an intermediary between the highly reactive amino group and the isocyanate, providing a controlled reaction pathway that achieves the desired urea linkage formation without the dangerous exothermicity of direct amino-isocyanate reactions

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If urea linkages are formed, then stability is improved, but viscosity increases due to strong hydrogen bonding

Engineering Contradiction:

ImprovestabilityVSAvoidviscosity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the functional group structure from amino to amide, which modifies the hydrogen bonding characteristics of the resulting urea linkage. This structural parameter change reduces the strength and extent of hydrogen bonding networks, thereby lowering viscosity while preserving the stability benefits of urea crosslinking

Inventive Principle:

Principle #35Parameter changes

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 use of amide-functionalized silanes in silylated polyurethane systems results in lower viscosity and enhanced mechanical properties, improving the processability and safety of adhesives, sealants, and coatings, while maintaining excellent adhesion and elastic properties across various substrates.

Implementation Method 1

reacting at least one polyol, at least one polyisocyanate, and at least one amide-functionalized silane

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

In the presence of atmospheric moisture these alkoxysilane-terminated polymers are capable of condensing with one another even at room temperature, eliminating the alkoxy groups

Methodology Applied

Scientific EffectHydrolysis: Hydrolysis

Implementation Method 3

Urethane groups present an important advantage over urea-linkages due to their weaker intermolecular hydrogen bonding, resulting in polymers with lower viscosities

Methodology Applied

Scientific EffectHydrogen bonding:

Data Source

PatentUS11078323B2Silane coupling agents

Publication Date: 2021.08.03 HENKEL KGAA

AI summary

The present invention discloses silylated polyurethanes obtainable by reacting at least one polyols, at least one polyisocyanates, at least one amide-functionalized silanes of the general formula (I) as described herein and their preparation methods, curable compositions comprising the silylated polyurethanes and their use as adhesive, sealant, spray foam and/or coating.