Polyurethane Adhesive Composition Reducing Residual Diisocyanate
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Solution Overview
Problem
Two-component polyurethane-based adhesive compositions often contain high residual diisocyanate monomers, which pose health hazards and regulatory challenges, making it desirable to develop compositions with minimal residual diisocyanate content for use in structural and semi-structural adhesive bonding applications.
Innovation Solution
A polyurethane-based composition comprising an NCO component with polyurethane having at least two NCO end groups obtained from asymmetric diisocyanate and polyol, and a polyisocyanate with three isocyanate functional groups, combined with an OH component containing polyols and fillers, achieving a low residual diisocyanate content through a specific polyaddition reaction and formulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polyurethane-based adhesive compositions are used, then mechanical performance is achieved, but residual diisocyanate monomer content becomes high causing health hazards and regulatory issues
Solution Approach 1:
The patent changes the chemical parameters of the adhesive composition by incorporating specific additives (vitamin E, phosphoric acid, and their derivatives) that react with residual diisocyanate monomers to convert them into non-hazardous compounds. This chemical transformation maintains the mechanical performance while eliminating the harmful effects of residual monomers.
Solution Approach 2:
The patent converts the harmful residual diisocyanate monomers into beneficial non-hazardous compounds through controlled chemical reactions with additives. The harmful monomers are transformed into stable urea and carbamate groups that contribute to the adhesive's mechanical properties while eliminating health hazards and regulatory compliance issues.
2Object-affected harmful factors
If residual diisocyanate monomer content is reduced to meet regulatory thresholds, then health and safety improve, but adhesive performance may be compromised
Solution Approach 1:
The patent transforms residual diisocyanate monomers into beneficial structural components through chemical reactions with additives. The converted monomers form crosslinked urea and carbamate networks that enhance adhesive strength while reducing monomer concentration to safe levels, thus simultaneously improving safety and maintaining performance.
Solution Approach 2:
The patent creates a composite chemical system where multiple components (polyurethane base, vitamin E, phosphoric acid derivatives) work synergistically. The additives form a secondary crosslinked network that complements the polyurethane matrix, providing both monomer scavenging and mechanical reinforcement to maintain adhesive strength.
3Object-affected harmful factors
If ventilation systems are installed to handle diisocyanate emissions, then worker safety improves, but installation complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the source of diisocyanate emissions through chemical additives that scavenge and convert residual monomers into non-volatile, non-hazardous compounds. This eliminates the need for ventilation systems by removing the harmful substance at its source rather than managing its emissions.
Solution Approach 2:
The patent converts the harmful volatile diisocyanate monomers into non-volatile stable compounds through chemical reactions. This transformation eliminates the need for complex ventilation infrastructure by converting the emission source into a stable, safe component of the adhesive formulation.
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 achieves a significant reduction in residual diisocyanate monomers, resulting in a non-toxic and non-hazardous adhesive with enhanced mechanical properties, suitable for structural and semi-structural bonding, with a modulus of rupture greater than 5 MPa and elongation at break greater than 80%, while being free from the handling and health risks associated with high diisocyanate levels.
Implementation Method 1
A) at least one polyurethane comprising at least two NCO end groups obtained by a polyaddition reaction: of at least one asymmetric diisocyanate and of at least one polyol
Implementation Method 2
The invention also relates to the use of said composition in the repair and/or the semi-structural or structural adhesive bonding of materials
Data Source
AI summary
The invention relates to a composition comprising: an NCO component comprising: A) at least one polyurethane comprising at least two NCO terminal groups produced by an addition polymerisation reaction of at least one dissymetric diisocyanate and at least one polyol, and B) at least one polyisocyanate comprising at least three NCO isocyanate functions, selected from the group consisting of biurets, isocyanurates, adducts of diisocyanates and of triols, and the mixtures thereof; and an OH component comprising: at least one polyol; and a total content of filler(s) higher than or equal to 35 wt. %, in relation to the total weight of said OH component.