Polyurethane Epoxy Coating Partial Capping Strategy
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Solution Overview
Problem
Conventional polyurethane-epoxy resin hybrid (PEH) coating systems face issues with mechanical stability due to the formation of separate epoxy resin and polyurethane domains during curing, and problems such as reduced reactivity and incomplete deblocking reactions with capping agents, which affect the mechanical properties of the resulting coating.
Innovation Solution
A two-component coating composition where the NCO end sites of the polyurethane prepolymer are partly bound to OH groups of the epoxy resin and partly to a capping agent, with a portion of the epoxy resin remaining free, improving the bonding and reducing the need for additional capping agents during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional PEH systems use completely capped polyurethane prepolymer with capping agents, then storage stability is improved, but mechanical stability deteriorates due to formation of separate epoxy resin domains and polyurethane domains
Solution Approach 1:
The patent applies local quality by creating distinct regions within the coating: capped polyurethane prepolymer regions for storage stability and free epoxy resin regions for mechanical integrity. The NCO end sites are selectively capped only when not bound to OH groups of epoxy resin, creating localized functional zones that simultaneously provide both storage stability and mechanical stability without forming separate domains.
Solution Approach 2:
The patent merges the functions of capping agents and epoxy resin by having NCO end sites bound to both OH groups of epoxy resin and capping agents simultaneously. This combination eliminates the need for complete capping while maintaining storage stability, and prevents formation of separate domains by integrating epoxy resin into the polyurethane matrix through covalent bonding.
2Stability of the object's composition
If conventional PEH systems use complete capping of NCO end sites, then reactivity is reduced for storage, but curing completeness deteriorates due to decapping/deblocking reaction problems
Solution Approach 1:
The patent applies partial action by capping only a portion of the NCO end sites with capping agents, specifically those not bound to OH groups of epoxy resin. This partial capping provides sufficient storage stability while leaving enough uncapped NCO sites and free epoxy resin to ensure complete and reliable curing without decapping problems, achieving both storage stability and curing completeness.
3Stability of the object's composition
If conventional PEH systems use high concentration of capping agent for complete capping, then storage stability is improved, but mechanical stability deteriorates due to plasticizer effects
Solution Approach 1:
The patent changes the parameter of capping agent concentration by reducing it to only the amount needed for partial capping of NCO end sites not bound to epoxy resin. This parameter change eliminates plasticizer effects while maintaining storage stability, and the freed capping agent can be used in smaller amounts that do not compromise mechanical stability.
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
This approach enhances mechanical stability, reduces the release of capping agents, and allows for faster and more complete curing at room temperature, improving storage stability and mechanical properties while minimizing volatile organic compounds (VOCs) and the need for solvents.
Implementation Method 1
the NCO end sites of the polyurethane prepolymer are partly bound to OH groups of the epoxy resin
Implementation Method 2
the NCO end sites of the polyurethane prepolymer are partly bound to a capping agent
Implementation Method 3
Curing of the coating composition is achieved by mixing the resin component (A) and the hardener component (B)
Data Source
AI summary
The present invention relates to a two-component coating composition comprising a resin component (A) containing at least one curable resin as a curable component, and a hardener component (B) containing a curing agent for the curable resin of the resin component (A), wherein the resin component (A) comprises at least one polyurethane prepolymer, at least one epoxy resin having OH groups, and at least one capping agent. The two-component coating composition is characterized in that the NCO endpoints of the polyurethane prepolymer are partly bonded to OH groups of the epoxy resin and partly to the capping agent, and a further portion of the epoxy resin is present freely in the resin component (A).The present invention further relates to methods for producing a resin component (A) of the two-component coating composition according to the invention, as well as the use of the two-component coating composition as a floor coating or for concrete repair.