Dual-Curing Adhesive Composition for Automotive Bonding
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Solution Overview
Problem
Existing adhesive and sealant systems in the automotive industry face challenges with curing speed dependence on ambient conditions, particularly moisture levels, and incomplete curing due to temperature limitations, leading to inefficiencies in bonding large or complex components.
Innovation Solution
A one-component adhesive/sealant composition that combines heat and moisture curing mechanisms, using an isocyanate-functional prepolymer and a polyamine with a melting point above 55°C, allowing for partial thermal curing followed by completion with ambient moisture, ensuring consistent bonding regardless of environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If one-component moisture-curing adhesive systems are used, then the adhesive can be applied in final assembly without complex mixing equipment, but the curing speed becomes very slow and highly dependent on ambient moisture conditions
Solution Approach 1:
The patent combines two curing mechanisms (heat-curing and moisture-curing) into a single adhesive system. The adhesive contains both heat-curing components (isocyanate-functional prepolymer) and moisture-curing components (polyamine with melting point above 55°C), allowing it to cure via either mechanism depending on available conditions, thus achieving both ease of application and acceptable curing speed
Solution Approach 2:
The patent changes the curing parameters by introducing a dual-curing system where the adhesive can cure at lower temperatures through moisture reaction while also being activatable by heat. This allows the adhesive to cure effectively in final assembly conditions without requiring high-temperature ovens, resolving the contradiction between ease of application and curing speed
2Productivity
If two-component adhesive systems are used, then the curing reaction is fast and less dependent on ambient conditions, but the system requires complex mixing and dosing technology with intensive maintenance
Solution Approach 1:
The patent merges the advantages of two-component systems (fast curing) with the simplicity of one-component systems (easy application). By incorporating both heat-curing and moisture-curing components into a single adhesive formulation, the system achieves fast curing without requiring separate components, mixing equipment, or dosing systems, thus eliminating the complexity and maintenance requirements while maintaining productivity
3Productivity
If high temperatures are used to cure the adhesive joint, then the curing reaction is fast, but large mass parts do not reach the necessary reaction temperature during passage through the oven, resulting in incomplete curing
Solution Approach 1:
The patent changes the curing temperature parameter by introducing a dual-curing mechanism that allows curing at lower temperatures through moisture reaction. This ensures that even large mass parts that do not reach high temperatures in the oven can still cure completely through the moisture-curing pathway, thereby achieving both fast curing rates and complete curing reliability
Solution Approach 2:
The patent introduces moisture as an intermediary curing agent that enables complete curing without requiring high temperatures. The moisture-curing component acts as a mediator that allows the adhesive to cure completely even when thermal energy is insufficient, thus resolving the contradiction between curing rate and curing completeness
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 dual curing mechanism ensures complete curing of adhesive joints, even in areas that may not reach the required temperature, and reduces the impact of ambient humidity variations, providing strong and consistent bonds in automotive applications.
Implementation Method 1
one-component adhesive/sealant compositions that can be cured both by moisture and (partially) by heat
Implementation Method 2
a method for curing the one-component compositions by the action of heat, followed from further hardening by moisture
Data Source
AI summary
Heat- and moisture-curing compositions which comprise at least one isocyanate-functional prepolymer having substantially terminal isocyanate groups and at least one polyamine having at least 2 primary or secondary amino groups per molecule and a melting point above 55°C are suitable for curing by 2 curing mechanisms. The composition may be at least partly thermally cured, and alternatively may cure completely with ambient atmospheric moisture. For this purpose the solid polyamine is required to have an average particle size of 5 to 50 µm and be insoluble in the prepolymer preparation at temperatures below 40°C. In accordance with the invention it is used in a substoichiometric amount in relation to the isocyanate groups of the prepolymer.