Thickness-Tolerant Bonding Primer for Low-Temperature Metal Adhesion
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Solution Overview
Problem
Existing bonding primers for metallic surfaces in aerospace and automotive industries face challenges in maintaining uniform thickness and adhesive strength, particularly at low temperatures, leading to reduced peel strength and corrosion issues.
Innovation Solution
A solvent-based bonding primer composition containing epoxy resins, silane compounds, core-shell rubber particles, and organic solvents, applied via spray or brushing, forms a curable film that enhances toughness and adhesion, ensuring uniform thickness and compatibility with curable adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a bonding primer is applied by spraying onto a large metal surface, then the primer layer can be applied to the surface, but the thickness becomes non-uniform (varying from 0.1 mil to 0.3 mil or above) due to limited spray nozzle coverage area and distance variation
Solution Approach 1:
The patent modifies the primer formulation by incorporating specific polymer additives and adjusting the chemical composition to create a thickness-tolerant bonding primer. This parameter change in the primer chemistry allows the coating to maintain consistent bonding performance despite thickness variations from 0.1 mil to 0.3 mil, resolving the contradiction between spray application efficiency and thickness uniformity.
2Quantity of substance
If the primer layer thickness exceeds about 0.25 mil (6.4 μm), then more primer material is applied to ensure coverage, but the peel strength drops significantly, especially at low temperatures such as −67° F. (−55° C.)
Solution Approach 1:
The patent changes the chemical parameters of the primer by incorporating specific polymer additives that provide thickness tolerance. This allows the primer to maintain low-temperature peel strength even when applied at thicker layers (0.3 mil or above), resolving the contradiction between material application quantity and peel strength.
Solution Approach 2:
The patent creates a composite primer formulation by combining epoxy resins with specific polymer additives and other components. This composite material structure provides both the bonding functionality and the thickness tolerance needed to maintain peel strength at low temperatures despite varying application thicknesses.
3Strength
If a primer layer is applied to maintain bonding strength, then adhesion is improved, but the handling properties and overall performance may be compromised due to thickness sensitivity
Solution Approach 1:
The patent modifies the primer's chemical composition by incorporating specific polymer additives that decouple the relationship between thickness and handling properties. This parameter change allows the primer to provide consistent bonding strength across a range of thicknesses (0.1-0.3 mil) while maintaining acceptable handling properties, resolving the contradiction between adhesive strength and ease of operation.
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 primer composition achieves high peel strength at low temperatures and provides long-term corrosion protection, maintaining consistent performance across varying thicknesses without compromising handling properties.
Implementation Method 1
containing: one or more epoxy resins, curing agent(s), a silane compound
Implementation Method 2
a low amount of core-shell rubber (CSR)... The CSR particles may be in nanometer size (below 100 nm), submicron size (100 nm to 1000 nm) or micron size (1 micron to 100 microns)
Data Source
AI summary
Disclosed herein is a solvent-based bonding primer composition containing one or more organic solvents, one or more epoxy resins, one or more curing agents, a silane compound, and a low amount of core-shell rubber particles in nanometer size, submicron or micron size. Also disclosed is a method of applying the solvent-based bonding primer composition onto a metallic surface of a first substrate prior to bonding the metallic surface to a second substrate via a curable adhesive.