Epoxy Resin Toughness Improvers for Thermal Expansion
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Solution Overview
Problem
Heat-curing epoxy resin compositions fail to maintain structural connections between substrates with different thermal expansion coefficients, leading to stress and potential failure during the curing process due to differential expansion and contraction.
Innovation Solution
A one-component thermosetting epoxy resin composition is developed, incorporating a toughness improver, such as a terminally blocked polyurethane prepolymer, with a specific weight ratio to the epoxy resin, which enhances the maximum linear expansion and mechanical properties, allowing the composition to withstand thermal stresses without bond failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat-curing epoxy resin composition is used for bonding substrates with different thermal expansion coefficients, then mechanical properties for structural bonding are achieved, but high stresses during heat curing cause bond failure or substrate deformation
Solution Approach 1:
The patent modifies the chemical composition parameters of the epoxy resin system by incorporating specific flexibilizing agents and curing agents in controlled ratios. This changes the physical properties of the cured resin, particularly its thermal expansion coefficient and stress tolerance, allowing it to accommodate differential expansion between substrates while maintaining bond strength
Solution Approach 2:
The patent creates a composite epoxy resin composition by combining multiple components: epoxy resin base, flexibilizing agents (such as polyether polyols or silane-modified polymers), curing agents, and optional fillers. This composite structure provides both the mechanical strength needed for structural bonding and the thermal flexibility to withstand differential expansion stresses
2Strength
If standard epoxy resin composition is used, then good mechanical strength is achieved, but maximum linear expansion is insufficient to accommodate thermal stress
Solution Approach 1:
The patent specifically adjusts the molecular structure and composition parameters of the epoxy resin to increase its elongation at break and linear expansion capacity. By selecting flexibilizing agents with appropriate molecular weights and functional groups, and optimizing their concentration (typically 5-50 wt% of total resin), the resin achieves both enhanced expandability and maintained strength
Solution Approach 2:
The patent introduces localized flexibility into the epoxy resin matrix through dispersed flexibilizing agent domains. These domains act as stress-absorbing regions that enable local deformation and expansion while the overall matrix maintains its structural integrity and bonding strength
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 exhibits improved mechanical properties and increased maximum linear expansion, enabling it to maintain structural integrity and withstand high stresses during heat curing, thus ensuring a durable adhesive connection.
Implementation Method 1
The toughener D is a terminally blocked polyurethane prepolymer of formula (I)... to increase the maximum length expansion Max. stretch a one-component heat-curing epoxy resin composition
Data Source
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AI summary
The present invention relates to the use of toughness improvers based on terminally blocked polyurethane prepolymers for increasing the maximum linear expansion of single component heat-curing epoxy resin compositions, in particular for joining substrates having different thermal expansion coefficients, in particular in the framework of transport agents or white goods.