Three-Component Polyurethane Adhesive with Thiol Catalyst
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Solution Overview
Problem
Two-component polyurethane compositions used as lamination adhesives face challenges with high sensitivity to relative humidity, inadequate storage stability, and poor adhesion on metal surfaces, particularly when curing rapidly and having short pot lives.
Innovation Solution
A three-component polyurethane composition comprising a polyol with thiol groups, a metal catalyst for forming thio complexes, and a polyisocyanate, which are packaged separately and mixed only before application, providing adjustable pot life and open time, improved storage stability, and enhanced adhesion on metal surfaces, while being less sensitive to high humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high proportions of isocyanates are used to achieve rapid curing, then curing speed is improved, but pot life becomes too short for practical use
Solution Approach 1:
The patent divides the adhesive system into three separate components (polyol component, isocyanate component, and catalyst component) that are packaged and stored separately. This segmentation allows the reactive components to remain stable during storage and transport, then combines them in controlled ratios during application to achieve both adequate pot life and rapid curing when needed.
Solution Approach 2:
The patent prepares the adhesive components in advance in a stable, non-reactive state by separating the reactive isocyanate and polyol components. The catalyst is also pre-packaged separately. This preliminary preparation allows the system to maintain stability during storage while enabling rapid curing when the components are mixed in the correct proportions during application.
2Loss of time
If two-component polyurethane compositions are used to achieve rapid curing, then curing time is reduced, but sensitivity to relative humidity increases
Solution Approach 1:
The patent segments the adhesive system into three separate components, isolating the moisture-sensitive isocyanate component from environmental humidity during storage and transport. The catalyst component is also separated to control its activity. This segmentation reduces sensitivity to relative humidity while maintaining rapid curing capability when components are properly mixed.
Solution Approach 2:
The patent introduces a catalyst component as an intermediary that mediates the curing reaction. By controlling when and how the catalyst mixes with the polyol and isocyanate components, the system achieves rapid curing while being less sensitive to ambient humidity conditions during application.
3Speed
If two-component polyurethane compositions are used for rapid curing, then curing speed is improved, but storage stability deteriorates
Solution Approach 1:
The patent divides the adhesive into three stable components that can be stored separately without degradation. The polyol, isocyanate, and catalyst remain stable in their separate containers, preventing premature reaction. This segmentation maintains storage stability while enabling rapid curing when the components are combined in the correct proportions during application.
4Loss of time
If two-component polyurethane compositions are used to achieve rapid curing, then curing time is reduced, but adhesion on metal surfaces becomes inadequate
Solution Approach 1:
The patent segments the adhesive system to allow proper formulation of each component, including adding adhesion promoters and modifiers to the polyol component that enhance metal surface bonding. The separate component structure enables optimization of adhesion properties without compromising curing speed.
Solution Approach 2:
The patent creates a composite adhesive system combining polyol, isocyanate, and catalyst components with carefully selected formulations. This composite approach allows incorporation of adhesion-enhancing additives and modifiers that improve bonding to metal surfaces while maintaining rapid curing characteristics.
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 cures rapidly with excellent mechanical properties, maintaining stability and adhesion even at high humidity levels, allowing for efficient processing and reduced cycle times in industrial applications.
Implementation Method 1
a metal catalyst for the curing of the composition which can form thio complexes
Implementation Method 2
at least one metal catalyst for the curing of the composition which can form thio complexes
Data Source
AI summary
A three-component polyurethane composition consisting of a first, a second and a third component, the first component containing a polyol having an OH functionality in the range from 1.5 to 4 and an average molecular weight in the range from 250 to 15000 g/mol and a compound having at least one thiol group, the second component containing at least one metal catalyst for the reaction of hydroxyl groups and isocyanate groups, which can form thiol complexes and preferably has a drying agent, and the third component containing at least one polyisocyanate, the molar ratio of all thiol groups of the compound to all metal atoms of the metal catalyst being between 1:1 and 250:1.