One-Component Adhesive Compositions Using Heat-Activated Lewis Acid Catalyst
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Solution Overview
Problem
Current epoxy-based structural adhesives often have poor resilience, low elongation, and lap shear strength, making them unsuitable for high-strength, load-bearing applications that require storage-stable, one-component systems.
Innovation Solution
A process for creating a one-component (1K) adhesive by reacting a polyepoxide compound with a polyol composition in the presence of a heat-activated Lewis acid catalyst, which catalyzes the reaction between epoxide and hydroxyl groups at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional epoxy 1K systems are used, then storage stability is achieved, but lap shear strength and resilience are poor
Solution Approach 1:
The system is segmented into two functional parts: a stable polyepoxide-polyol base composition and a heat-activated Lewis acid catalyst. The catalyst is incorporated in a dormant form that does not react at storage temperatures but activates at elevated temperatures to initiate curing, thus achieving both storage stability and high strength.
Solution Approach 2:
The catalyst activation is controlled by temperature parameter changes. At low temperatures (storage), the catalyst remains dormant. At high temperatures (curing), the catalyst becomes active, enabling the reaction to proceed and achieving high lap shear strength while maintaining storage stability.
2Strength
If polyisocyanates or polyamine crosslinkers are used to improve strength, then lap shear strength increases, but the system becomes less stable and requires two-component mixing
Solution Approach 1:
The invention merges the polyepoxide, polyol, and heat-activated Lewis acid catalyst into a single stable one-component system. This eliminates the need for separate mixing of multiple components while achieving high lap shear strength through the controlled activation of the catalyst at elevated temperatures.
Solution Approach 2:
The heat-activated Lewis acid catalyst acts as an intermediary that enables the reaction between polyepoxide and polyol without requiring polyisocyanates or polyamines. The catalyst facilitates the curing process while maintaining system stability and simplicity.
3Strength
If room temperature curing is used, then ease of application is improved, but resilience and elongation are reduced
Solution Approach 1:
The curing temperature parameter is changed from room temperature to elevated temperature (above 100°C). This parameter change enables the heat-activated catalyst to become active, producing adhesives with improved resilience and elongation while maintaining ease of application through the one-component 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 resulting 1K PEEP compositions exhibit improved lap shear strength, resilience, and elongation compared to conventional epoxy 1K systems, while avoiding the use of polyisocyanates or polyamine crosslinkers.
Implementation Method 1
a heat-activated Lewis acid catalyst adapted to melt, dissolve, or dissociate to generate a species capable of catalyzing a reaction between an epoxide group of the epoxide compound and a hydroxyl group of the polyol at temperatures greater than 100°C
Data Source
AI summary
One-component (1 K) adhesive compositions ("PEEP" compositions) and a process for making them are disclosed. A polyepoxide is reacted with a polyether polyol composition, a polyester polyol composition, or both in the presence of a heat-activated Lewis acid catalyst at a temperature within the range of 100°C to 220°C for a time effective to cure the adhesive. The compositions are storage-stable under ambient conditions. Compared with conventional epoxy compositions, the 1 K PEEP compositions offer improved room temperature lap shear strength, better resilience, and higher elongation. The 1 K PEEP systems deliver a desirable balance of physical and mechanical properties while avoiding polyisocyanates and polyamine crosslinkers.