Imidazolium Salt Latent Catalyst for Epoxy Curing
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Solution Overview
Problem
Existing epoxy curing systems require high temperatures for curing, leading to energy inefficiencies and potential unwanted secondary reactions, while maintaining the mechanical and performance properties of the cured systems is a challenge, especially in one-component systems that need to remain stable at room temperature.
Innovation Solution
The use of 1,3-substituted imidazolium salts with a dicyanamide anion as latent catalysts, which are miscible with epoxy compounds, remain stable at room temperature, and initiate curing at lower temperatures below 200°C, allowing for energy savings and improved properties such as hardness and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high reactivity amino compounds or acid anhydride compounds are used for curing epoxy compounds, then curing speed and reactivity are improved, but premature curing occurs during storage and handling
Solution Approach 1:
The patent applies preliminary action by incorporating the latent catalyst into the epoxy compound during manufacturing, allowing the system to be prepared in advance without premature curing. The catalyst remains dormant at room temperature and only becomes active when heated to the curing temperature range (above 80°C), thus enabling pre-mixing and storage while maintaining stability, and activating curing only when needed during the curing process
2Stability of the object's composition
If high curing temperatures (above 200°C) are used to activate latent catalysts, then storage stability is improved, but energy consumption increases and unwanted secondary reactions occur
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of the latent catalyst to have a lower decomposition temperature. The catalyst is designed to decompose and become active in the temperature range of 80-200°C, which is lower than conventional latent catalysts that require temperatures above 200°C. This parameter change enables curing at reduced temperatures, decreasing energy consumption and avoiding secondary reactions while maintaining adequate storage stability at room temperature
3Loss of energy
If conventional latent catalysts are used to achieve low curing temperatures, then energy consumption is reduced, but mechanical properties and performance of the cured system are impaired
Solution Approach 1:
The patent applies parameter changes by optimizing the chemical structure of the imidazolium salt catalyst, specifically using dicyanamide anion, which enables effective catalysis at lower temperatures (80-200°C) while maintaining or improving the mechanical properties of the cured epoxy system. This structural parameter change allows the catalyst to be sufficiently active at reduced temperatures without compromising the strength and performance of the final cured material
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 1,3-substituted imidazolium salts with a dicyanamide anion enable efficient curing of epoxy compounds at lower temperatures, maintaining or improving mechanical properties and reducing energy costs, while ensuring stability as a one-component system.
Implementation Method 1
Their decomposition above 175° C. releases 1-alkylimidazoles, which then bring about the cure
Implementation Method 2
Various possibilities are known for curing. Starting from epoxy compounds having at least two epoxy groups it is possible, with an amino compound or with an acid anhydride compound having at least two amino groups or at least one anhydride group, respectively, for curing to take place through a polyaddition reaction (chain extension)
Data Source
AI summary
The use of 1,3-substituted imidazolium salts of the formula Iin whichR1 and R3 independently of one another are an organic radical having 1 to 20 C atoms,R2, R4, and R5 independently of one another are an H atom or an organic radical having 1 to 20 C atoms, it also being possible for R4 and R5 together to form an aliphatic or aromatic ring, andX is a dicyanamide anionas latent catalysts for curing compositions comprising epoxy compounds.