Blocked Polyurethane Prepolymer for Isocyanate-Free Floor Coatings
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Solution Overview
Problem
Conventional polyurethane prepolymers with free isocyanate groups pose health risks and storage instability issues, and their use in two-component coating compositions leads to incomplete deblocking, low mechanical strength, and phase separation in polyurethane-epoxy resin hybrids, which are unsuitable for floor coatings and concrete repair.
Innovation Solution
A polyurethane prepolymer with NCO endpoints completely blocked by covalent bonding to 1,2-glycerol carbonate and optionally epoxy resin groups, ensuring irreversible blocking and availability for crosslinking reactions without releasing isocyanate groups, using sustainable and cost-effective production methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional capping agents (phenols, secondary amines, ketoximes, amides) are used to block NCO endpoints, then storage stability is improved and health risks are reduced, but incomplete deblocking occurs leading to insufficient crosslinking and low mechanical strength
Solution Approach 1:
The patent changes the chemical parameter of the capping agent from conventional phenols, amines, ketoximes, or amides to 1,2-glycerol carbonate. This parameter change enables complete deblocking during curing while maintaining storage stability, thereby achieving both high mechanical strength and reliable storage properties.
Solution Approach 2:
The patent extracts the problematic conventional capping agents from the system and replaces them with 1,2-glycerol carbonate. This extraction eliminates the deblocking incompleteness issue inherent in conventional capping agents while preserving the storage stability benefit.
2Object-affected harmful factors
If conventional capping agents are used to block NCO endpoints, then health risks from free isocyanate groups are reduced, but high concentration of free capping agent remains causing undesirable plasticizing effects
Solution Approach 1:
The patent changes the chemical identity of the capping agent to 1,2-glycerol carbonate, which undergoes complete reaction during curing without leaving residual plasticizing effects. This parameter change simultaneously maintains health safety by blocking free isocyanate groups and eliminates the mechanical strength reduction caused by residual capping agents.
3Reliability
If polyurethane prepolymer and epoxy resin are combined in PEH systems, then crosslinking is improved, but phase separation occurs between epoxy resin domains and polyurethane domains impairing mechanical stability
Solution Approach 1:
The patent merges the polyurethane prepolymer and epoxy resin at the molecular level through covalent bonding of 1,2-glycerol carbonate to NCO endpoints, creating a hybrid structure. This merging prevents macroscopic phase separation while maintaining the crosslinking benefits of both components, thereby achieving both high crosslinking degree and composition stability.
Solution Approach 2:
The patent creates a composite polyurethane-epoxy resin hybrid material where 1,2-glycerol carbonate serves as a linking unit between polyurethane and epoxy components. This composite structure ensures molecular-level mixing that prevents phase separation while utilizing the advantageous properties of both material systems for enhanced crosslinking and stability.
4Reliability
If conventional PEH systems are used, then coating performance is achieved, but incomplete deblocking and phase separation lead to insufficient crosslinking and low mechanical strength
Solution Approach 1:
The patent changes the capping agent parameter to 1,2-glycerol carbonate in the PEH system, enabling complete deblocking during curing. This change ensures thorough crosslinking between polyurethane and epoxy components, thereby achieving both reliable coating performance and high mechanical strength without the deficiencies of conventional systems.
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 solution provides a high degree of cross-linking in the coating, improves mechanical strength, and enhances storage stability, while being isocyanate-free and reducing environmental impact, suitable for floor coatings and concrete repair applications.
Implementation Method 1
the NCO endpoints of the polyurethane prepolymer are completely blocked by covalent bonding
Implementation Method 2
the blocked polyurethane prepolymer remains available for crosslinking reactions with the hardener component (B)
Data Source
Figure 1~3
AI summary
The present invention relates to a polyurethane prepolymer, wherein the NCO endpoints of the polyurethane prepolymer are completely blocked by covalent bonding, characterized in that the NCO endpoints of the polyurethane prepolymer are at least partially bonded to the OH group of 1,2-glycerol carbonate and optionally partially bonded to OH groups of an epoxy resin. The present invention further relates to methods for producing the polyurethane prepolymer according to the invention. The present invention also relates to a two-component coating composition comprising a resin component (A) containing at least one polyurethane prepolymer according to the invention as a curable component, and a hardener component (B) containing a curing agent for the polyurethane prepolymer in the resin component (A).Furthermore, the present invention relates to the use of the two-component coating composition according to the invention as a floor coating or for concrete repair.