Curable Composition with Polymeric Toughener in Amine Curative
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Two-part curable compositions, particularly in the automotive and aerospace industries, face challenges with brittleness and amine blushing issues due to the use of short chain aliphatic or cyclic aliphatic amines, which affect the peel performance and bond strength of structural adhesives, especially at high temperatures.
Innovation Solution
Incorporating high molecular weight rubbery or thermoplastic polymers into the curative part of a two-part curable composition, dissolved in a low viscosity amine, to create an amine-polymer solution that functions as a hardener, which enhances peel and shear strength while mitigating the amine blush effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If short chain aliphatic or cyclic aliphatic amines are used as curatives, then the curable composition can be mixed and cured at room temperature, but the cured composition exhibits brittleness and degraded peel performance
Solution Approach 1:
The patent uses composite materials by combining polymeric tougheners (rubbery or thermoplastic polymers) with amine curatives to create a hybrid curative system. This composite approach allows the composition to maintain room temperature cure capability while incorporating toughening agents that improve peel performance and reduce brittleness of the cured adhesive.
2Strength
If polymeric tougheners are dispersed into the epoxy resin component, then the peel strength performance is improved, but the viscosity increases beyond acceptable levels for manual mixing
Solution Approach 1:
The patent segments the adhesive system into two separate components: the epoxy resin component and the curative component. The polymeric tougheners are placed exclusively in the curative component rather than being dispersed in the epoxy resin. This segmentation allows each component to maintain optimal viscosity for handling while achieving the desired peel strength through the toughened curative.
Solution Approach 2:
The amine curative acts as an intermediary medium that dissolves the polymeric tougheners. By using the liquid amine as a solvent for the toughening agents, the patent achieves a curative component with appropriate viscosity that can be easily mixed with the epoxy resin, while still providing the toughening effect needed for high peel strength.
3Object-generated harmful factors
If lower viscosity amines are used, then the amine blush effect is reduced, but brittleness increases in the cured composition
Solution Approach 1:
The patent creates a composite curative system by dissolving polymeric tougheners in low viscosity amines. This composite approach allows the use of low viscosity amines (which reduce amine blush) while incorporating polymeric tougheners that compensate for the increased brittleness, achieving both reduced amine blush and improved toughness.
4Strength
If high molecular weight tougheners are used, then the peel strength is significantly improved, but the viscosity of the epoxy resin component increases beyond acceptable levels
Solution Approach 1:
The patent segments the toughening agents from the epoxy resin component and places them in the curative component. This allows high molecular weight tougheners to be used without increasing the viscosity of the epoxy resin, maintaining easy mixability while achieving high peel strength through the toughened curative system.
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 solution enables the production of paste adhesives that can be mixed and cured at room temperature, providing high peel and shear strength over a wide temperature range, including temperatures exceeding 180°F (82°C), and reduces the amine blush issue, thus overcoming the limitations of prior art approaches.
Implementation Method 1
a curative part comprising a polymeric toughener dissolved in an amine
Implementation Method 2
a base part comprising an amine-reactive curable resin; and a curative part comprising a polymeric toughener dissolved in an amine
Data Source
AI summary
Provided are curable compositions including a base part comprising an amine-reactive curable resin and a curative part comprising a polymeric toughener dissolved in an amine. The polymeric toughener, optionally a rubbery polymer or thermoplastic polymer, is solid at ambient conditions with a weight average molecular weight of at least 5,000 g/mol while the amine is a liquid at ambient conditions. The curable composition is cured by mixing the base and curative parts with each other. Hardened compositions obtained thereof can achieve increased toughener loading, resulting in high peel and shear strength performance over a wide range of temperatures, including at temperatures exceeding 180° F. (82° C.).