Alkoxysilane-Functionalized Urethanes for Hard Coatings
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Solution Overview
Problem
Current alkoxysilane-terminated polyurethanes used as sole binders in room temperature-curing systems result in coatings with moderate hardness, and existing allophanate-functionalized systems do not meet the requirements for highly cross-linked, hard coatings.
Innovation Solution
Development of alkoxysilane-functionalized and allophanate-functionalized urethanes, produced through specific reactions involving monourethanes, diisocyanates, and diols/polyols, which can be used as sole binders in both cold and hot curing systems to create highly cross-linked, hard coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If alkoxysilane-terminated polyurethanes are used as sole binders in room temperature-curing systems, then the coating system can be applied and cured at room temperature, but the resulting coatings exhibit only moderate hardness
Solution Approach 1:
The patent combines multiple functional groups (alkoxysilane, isocyanate, and allophanate) into a single binder molecule. This merging of functionalities allows the binder to simultaneously participate in urethane formation, allophanate crosslinking, and siloxane network formation, thereby achieving high hardness coatings while maintaining room temperature or low-temperature curing capability
Solution Approach 2:
The invention creates a composite molecular structure that integrates different functional moieties (silane groups, urethane linkages, and allophanate groups) within the same polymer chain. This composite approach enables the coating to form multiple types of crosslinks (siloxane, urethane, and allophanate), resulting in enhanced hardness and mechanical properties while retaining ease of application
2Stability of the object's composition
If existing allophanate-functionalized systems are used, then the coating can achieve cross-linking, but they do not meet the requirements for highly cross-linked, hard coatings
Solution Approach 1:
The patent introduces alkoxysilane groups at specific locations within the polyurethane chain (either at terminal positions or incorporated along the chain). These localized silane functionalities enable additional siloxane crosslinking in proximity to the allophanate crosslinks, creating regions of high cross-linking density that significantly enhance coating hardness and mechanical strength
3Strength
If multiple separate components are used to achieve high cross-linking and hardness, then the desired coating properties can be obtained, but the system complexity and number of components increase
Solution Approach 1:
The patent designs a multifunctional binder that performs multiple roles simultaneously: it forms urethane linkages through isocyanate-alcohol reactions, creates allophanate crosslinks through thermal rearrangement, and generates siloxane networks through silane condensation. This multi-functionality eliminates the need for separate crosslinking agents or additional components, simplifying the coating formulation while achieving high hardness and extensive cross-linking
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 alkoxysilane-functionalized and allophanate-functionalized urethanes enable the production of highly cross-linked, hard coatings with improved mechanical properties and chemical resistance, suitable for use in paint, adhesive, and sealant applications.
Implementation Method 1
Additional alkoxysilane groups can play an important role here, e.g. B. in terms of network density, chemical resistance and scratch resistance, primarily through the formation of siloxane and polysiloxane structures
Implementation Method 2
Molecules that have both alkoxysilane groups and isocyanate groups offer the possibility of inserting the functionalities resulting as reaction products, siloxanes and polyurethane groups, through one component
Implementation Method 3
Binders containing allophanate have been known for a long time. Alkoxysilane-functionalized allophanates are also known
Data Source
AI summary
The present invention relates to alkoxysilane-functionalized and allophanate-functionalized urethanes, processes for their production, coating materials containing them and their use.