Polyurethane Adhesive Composition Reducing Residual Monomers
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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, and existing compositions with low residual monomer content suffer from high viscosity, difficulty in extrusion, low reactivity, and limited mechanical performance.
Innovation Solution
A polyurethane-based composition comprising an —NCO component with polyurethane bearing NCO end groups obtained from a polyaddition reaction of a dissymmetric diisocyanate and polyol, and a polyisocyanate with at least three isocyanate functions, combined with an —OH component of specific polyols and a rheological agent, designed to minimize residual diisocyanate monomers and enhance mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional two-component polyurethane adhesive compositions are used, then elevated mechanical performance qualities are achieved, but high residual contents of diisocyanate monomers result in health hazards and regulatory challenges
Solution Approach 1:
The patent extracts and removes residual diisocyanate monomers from the polyurethane adhesive composition through purification processes during synthesis. This extraction eliminates the harmful factor (residual monomers causing health hazards) while preserving the beneficial mechanical performance qualities of the two-component polyurethane adhesive system.
Solution Approach 2:
The patent changes the chemical composition parameters by using purified polyurethane prepolymers with controlled molecular weights and specific NCO end group concentrations. By precisely controlling these parameters during synthesis and purification, the composition achieves low residual monomer content (below regulatory thresholds) while maintaining elevated mechanical performance.
2Object-affected harmful factors
If compositions with low residual monomer content are used, then health and safety issues are reduced, but high viscosity and difficulty in extrusion occur
Solution Approach 1:
The patent optimizes the viscosity parameter by controlling the molecular weight distribution and functionality of the polyurethane prepolymers used in the composition. By adjusting these parameters within specific ranges, the composition achieves low residual monomer content while maintaining extrudable viscosity levels, resolving the contradiction between safety and ease of operation.
Solution Approach 2:
The patent creates a composite adhesive system combining purified polyurethane prepolymers with specific complementary components. This composite formulation achieves low residual monomer content while the synergistic interaction between components maintains appropriate viscosity and extrusion properties, preventing the high viscosity problem associated with low-monomer compositions.
3Object-affected harmful factors
If compositions with low residual monomer content are used, then health and safety issues are reduced, but low reactivity and limited mechanical performance result
Solution Approach 1:
The patent optimizes the NCO/OH stoichiometric ratio and the molecular weight parameters of the polyurethane prepolymers to achieve maximum reactivity and mechanical performance. By precisely controlling these parameters while maintaining low residual monomer content through purification, the composition achieves both safety compliance and elevated mechanical performance qualities.
Solution Approach 2:
The patent develops a composite two-component system where purified polyurethane prepolymers are combined with specifically selected complementary components. This composite formulation ensures low residual monomer content while the synergistic interaction between components provides high reactivity and superior mechanical performance, overcoming the limitations of low-monomer compositions.
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 reduced residual diisocyanate content, improved extrudability, rapid cohesion, and high mechanical and adhesive properties, including tensile modulus and elongation at break, while being non-toxic and non-hazardous.
Implementation Method 1
at least one polyurethane including at least two NCO end groups obtained by a polyaddition reaction: of a composition comprising at least one dissymmetric diisocyanate; and of a composition comprising at least one polyol
Data Source
AI summary
The present invention relates to a composition comprising: —an —NCO component comprising: A) at least one polyurethane comprising at least two NCO end groups obtained by polyaddition reaction: of a composition comprising at least one diisocyanate, of a composition comprising at least one polyol, B) at least one polyisocyanate comprising at least three isocyanate NCO functions, selected from the group consisting of biurets, of isocyanurates, of adducts of diisocyanates and triols, and of mixtures thereof; an —OH component comprising: at least two polyols P1 having a number-average molecular weight of strictly less than 500 g/mol and at least one polyol P2 having a number-average molecular weight of strictly greater than 1000 g/mol, said composition comprising at least one rheology agent.