Epoxy Adhesive Composition for Stable Viscosity and Modifier Dispersion
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Solution Overview
Problem
Epoxy adhesive compositions face issues with re-aggregation of adhesive layer modifiers leading to increased viscosity over time, poor adhesiveness, and process failures such as nozzle clogging, especially when used with porous adherends.
Innovation Solution
An epoxy adhesive composition containing a modified polyvinyl acetal resin with an acid-modified group, combined with an epoxy resin, to improve dispersibility and stability of the adhesive layer modifier, forming a crosslinked structure with enhanced elasticity and mechanical strength, thereby reducing aggregation and viscosity increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive layer modifiers such as inorganic materials are added to improve durability or adhesiveness, then adhesiveness and durability are improved, but viscosity increases and process failures occur due to aggregation and sedimentation
Solution Approach 1:
A coupling agent is introduced as an intermediary substance between the inorganic adhesive layer modifier and the epoxy resin. The coupling agent has dual functionality: it bonds to the inorganic material surface through chemical reactions (such as silane coupling with oxide surfaces) and simultaneously reacts with the epoxy resin, creating a bridge that improves interfacial adhesion. This prevents aggregation of inorganic particles while maintaining their dispersibility in the adhesive matrix, thereby preserving viscosity stability and preventing sedimentation during storage and application.
Solution Approach 2:
The surface properties of inorganic adhesive layer modifiers are modified through treatment with coupling agents, which changes the surface chemistry and energy characteristics. This parameter change in surface properties enables better compatibility with the organic epoxy resin matrix, preventing particle aggregation and sedimentation while maintaining the desired adhesiveness and durability enhancements.
2Strength
If modified epoxy resin and rubber particles are used to improve adhesion strength, then shear adhesion strength and peel adhesion strength are improved, but durability is insufficient and adherend detachment occurs
Solution Approach 1:
The invention employs a composite adhesive system combining epoxy resin with specific polymers (polyurethane, polyester, or acrylic resin) in controlled ratios. This composite formulation integrates the high strength and rigidity of epoxy with the flexibility and toughness of the additional polymers, creating a balanced adhesive that maintains both high adhesion strength and superior durability. The composite nature allows the adhesive to withstand mechanical stress while resisting environmental degradation and adherend detachment.
3Duration of action of stationary object
If adhesive compositions are stored for long periods, then availability is maintained, but viscosity increases due to aggregation of adhesive layer modifiers
Solution Approach 1:
The coupling agent serves as a long-term stabilizing intermediary that continuously prevents aggregation of inorganic particles during storage. By maintaining strong interfacial bonding between particles and the resin matrix, the coupling agent ensures that the adhesive composition remains homogeneous and pumpable throughout the storage period, preserving both viscosity stability and application readiness.
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 maintains high adhesiveness and reduces process failures by preventing adhesive layer modifier aggregation, ensuring stable viscosity over time and improving bonding strength and flexibility.
Implementation Method 1
forming a crosslinked structure with enhanced elasticity and mechanical strength
Implementation Method 2
a modified polyvinyl acetal resin having a constitutional unit with an acid-modified group; an epoxy resin, the epoxy adhesive composition having a ratio of an acid-modified group equivalent of the modified polyvinyl acetal resin to an epoxy equivalent of the epoxy resin
Data Source
AI summary
The present invention provides an epoxy adhesive composition capable of reducing re-aggregation of an adhesive layer modifier, maintaining favorable viscosity for a long period of time, exhibiting high adhesiveness, and reducing process failures during application of the adhesive. Provided is an epoxy adhesive composition containing: a modified polyvinyl acetal resin having a constitutional unit with an acid-modified group; an adhesive layer modifier; and an epoxy resin, the epoxy adhesive composition having a ratio of an acid-modified group equivalent of the modified polyvinyl acetal resin to an epoxy equivalent of the epoxy resin (acid-modified group equivalent/epoxy equivalent) of 5.0 to 150.0, the epoxy adhesive composition having a number ratio of the acid-modified group to an epoxy group (acid-modified group number/epoxy group number) of 0.0005 to 0.5.