Thermosettable Epoxy Adhesive Sheet for Metal Panel Bonding
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Solution Overview
Problem
Existing methods for joining metal panels in vehicle closure systems require additional materials for sealing and corrosion resistance, and are not effective when the panels are contaminated with oil, necessitating a solution that provides strong bonding and corrosion resistance without the need for clamping or separate sealing materials.
Innovation Solution
A method using a thermosettable adhesive sheet comprising a mixture of high and low molecular weight epoxy compounds and an epoxy curing agent, applied between metal panels and heated to form a permanent bond, which is resistant to oil contamination and provides corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional adhesive methods are used to join metal panels, then bonding is achieved, but additional materials (sealants, coatings) are required for sealing and corrosion resistance
Solution Approach 1:
The patent combines multiple functions (adhesive bonding, sealing, and corrosion protection) into a single multi-functional adhesive composition. This eliminates the need for separate sealants and protective coatings, reducing the quantity of materials while maintaining reliable corrosion resistance through the integrated formulation.
Solution Approach 2:
The adhesive composition is designed to perform multiple functions simultaneously: it bonds metal panels together, seals the joint against moisture and contaminants, and provides corrosion protection. This multi-functional approach eliminates the need for additional specialized materials.
2Ease of manufacture
If adhesive is applied to oil-contaminated metal panels, then bonding should occur, but oil contamination reduces adhesive strength
Solution Approach 1:
The adhesive formulation is specifically designed to tolerate and even benefit from the presence of oil and grease contaminants on metal surfaces. The composition includes modifiers that allow the adhesive to adhere effectively to oily surfaces, converting what is traditionally a harmful contamination into a non-critical condition that does not compromise bond strength.
Solution Approach 2:
The patent modifies the chemical parameters of the adhesive system by incorporating specific epoxy compounds, polyesters, and modifiers that change the adhesive's interaction with oily surfaces. These parameter changes enable the adhesive to maintain adequate bond strength despite the presence of contaminants that would normally prevent proper adhesion.
3Strength
If adhesive provides strong bonding, then joint strength is achieved, but crash resistance and elongation at break may be compromised
Solution Approach 1:
The adhesive is formulated as a complex composite system combining epoxy resins, polyesters, plasticizers, and various modifiers. This composite structure allows the material to exhibit both high strength for joint integrity and sufficient elongation at break (5-15%) for crash resistance, achieving a balance between strength and ductility that single-material systems cannot provide.
Solution Approach 2:
The patent carefully adjusts the chemical composition parameters including the ratios of epoxy compounds, polyesters, and modifiers to optimize the balance between strength and elongation properties. By controlling the molecular weight distribution and cross-linking density, the adhesive achieves adequate bond strength while maintaining 5-15% elongation at break for crash resistance.
4Productivity
If automated adhesive application is used, then productivity increases, but precise control of adhesive properties is required
Solution Approach 1:
The adhesive is supplied in a pre-mixed, ready-to-apply formulation with all components thoroughly blended and degassed before application. This preliminary preparation ensures consistent rheological properties and eliminates the need for on-site mixing or adjustment, enabling automated application systems to deposit the adhesive with precise control over thickness and coverage.
Solution Approach 2:
The adhesive composition is designed with homogeneous distribution of all components including epoxy resins, polyesters, fillers, and modifiers. This homogeneity ensures consistent flow characteristics and curing behavior throughout the adhesive batch, allowing automated application equipment to maintain precise control over adhesive deposition without variation in material properties.
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 adhesive sheet enables strong bonding and sealing of metal panels, allowing for automated application and handling without clamping, while providing adequate corrosion resistance and crash resistance, even when applied to contaminated surfaces.
Implementation Method 1
heating the metal joint so as to cause thermosetting of the thermosettable composition of the adhesive sheet
Data Source
Figure 1~2
AI summary
In accordance with the present invention there is provided a method of making a metal part assembly, the method comprising: - providing a first metal part and a second metal part wherein at least one of the first and second metal part comprises a metal panel; - providing an adhesive sheet having a first portion near a first end of the adhesive sheet and a second portion near a second end opposite to the first end of the adhesive sheet, the adhesive sheet comprising a thermosettable composition that comprises a mixture of a first and second epoxy compound and an epoxy curing agent, wherein the first epoxy compound has a weight average molecular weight of at least 1000 g/mol and has an amount of epoxy groups of between 5 and 10 mole% and the second epoxy compound has a weight average molecular weight of not more than 400 g/mol and wherein the weight ratio of first to second epoxy compound is between 0.8 and 4; - adhering said first and second metal part together such that the adhesive sheet is provided between said first and second metal part thereby forming a metal joint; and heating the metal joint so as to cause thermosetting of the thermosettable composition of the adhesive sheet.