Low-Monomer Polyurea Composition With Fast Cure and High Strength
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Solution Overview
Problem
Existing polyurea compositions used as coatings contain residual monomeric diisocyanates, which are harmful to health and require safety precautions, leading to regulatory challenges and compromised mechanical properties like slow curing and reduced strength.
Innovation Solution
A polyurea composition with a monomeric diisocyanate content of less than 0.5% is achieved by using a polyetherurethane polymer and aliphatic polyisocyanate, obtained through a separation method, ensuring rapid curing and high mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If monomeric diisocyanate is used in excess in the preparation of the polymer and then removed by distillation, then the polymer has low viscosity and low residual monomeric diisocyanate content, but the polyurea composition shows slow curing, reduced strength, and weaknesses in adhesion development
Solution Approach 1:
The patent changes the chemical structure parameter of the diisocyanate from aromatic to aliphatic, using aliphatic polyisocyanates instead of aromatic monomeric diisocyanates. This parameter change allows achieving low residual monomer content (<0.5%) without the harmful effects, while maintaining or improving curing rate, tensile strength, and adhesion properties through the different reactivity and molecular structure of aliphatic isocyanates
Solution Approach 2:
The patent uses aliphatic polyisocyanates as temporary reactive components that fully react during curing, leaving no harmful residual monomers. These aliphatic isocyanates serve their purpose during the curing process and are consumed, unlike aromatic diisocyanates that leave persistent harmful residues requiring distillation removal
2Object-affected harmful factors
If formulations contain monomeric diisocyanates above 0.1% by weight, then hazard symbols and warning messages are required and regulations apply to sale and use, but reducing the content requires complex separation processes
Solution Approach 1:
The patent extracts and eliminates the harmful aromatic monomeric diisocyanate component from the formulation by using aliphatic polyisocyanates instead. This substitution removes the source of harmful residues, allowing the final product to contain less than 0.5% monomeric diisocyanates and avoid hazard labeling requirements without needing complex post-synthesis separation processes
Solution Approach 2:
The patent changes the key parameter of diisocyanate type from aromatic monomeric to aliphatic polymeric, which fundamentally alters the residual content profile. This parameter change enables compliance with safety regulations (<0.5% residual monomers) through simple distillation or even without separation processes, as the aliphatic polyisocyanates do not leave harmful monomeric residues
3Reliability
If polyurea compositions contain conventional polymers with isocyanate groups prepared by reacting polyols with monomeric diisocyanates, then good adhesion and elasticity are achieved, but the compositions contain residual monomeric diisocyanate content of 1% to 3% by weight
Solution Approach 1:
The patent uses aliphatic polyisocyanates as temporary reactive components that fully react during the curing process, leaving no harmful residues. These aliphatic isocyanates perform their function during curing and are consumed, eliminating the need for complex removal processes while ensuring safe final product with <0.5% residual monomers
Solution Approach 2:
The patent changes the diisocyanate parameter from aromatic monomeric to aliphatic polymeric, which maintains the necessary reactivity for good adhesion and elasticity while eliminating harmful residual monomers. The aliphatic structure provides comparable or superior performance with enhanced safety profile
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 composition allows safe handling without hazard labeling, with rapid curing, high tensile strength, and excellent elasticity, making it suitable for various applications.
Implementation Method 1
Polyurea compositions that crosslink through reaction of isocyanate groups with amine groups and cure to form elastomers
Implementation Method 2
remove the majority of the unconverted monomeric diisocyanate by means of a suitable separation method, especially by means of distillation
Data Source
AI summary
A polyurea composition containing monomeric diisocyanates in an amount of max. 0.5 wt. % and consisting of a first component containing a primary, aromatic diamine and a second component containing an isocyante-group-containing polyether urethane polymer containing monomeric diisocyantes in an amount of max. 0.5 wt. % and an aliphatic polyisocyanate with an NCO content of 8 to 25 wt. %.