Solid Polymeric Adhesives for Moldable High-Temperature Metal Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing adhesive compositions for adhering metal components in high-temperature environments face limitations in processing, shelf life stability, and tensile strength, particularly when exposed to elevated temperatures, and are not suitable for extrusion or injection molding before curing.
Innovation Solution
A polymeric adhesive composition comprising epoxy resins, high glass transition temperature thermoplastic polymers, impact modifiers, curatives, and optional fillers and blowing agents, which can be molded or extruded before curing, providing durable bonds with high tensile strength at elevated temperatures and improved shelf life stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high concentrations of liquid epoxy and low concentrations of polysulfone are used, then the adhesive can be processed by extrusion or injection molding, but the composition becomes tacky at elevated temperatures during shipping and storage
Solution Approach 1:
The patent changes the concentration parameters of epoxy resin and polysulfone to specific ranges (epoxy resin: 20-60 wt%, polysulfone: 10-40 wt%) to achieve a balance between processability and shelf life stability. This parameter optimization allows the composition to remain non-tacky during storage while maintaining extrudability and moldability.
Solution Approach 2:
The patent creates a composite material system combining epoxy resin, polysulfone, and optional third polymer components. This composite approach leverages the complementary properties of each component: epoxy provides adhesion and structural integrity, polysulfone provides high-temperature stability and processability, and the combination achieves both manufacturability and storage stability.
2Strength
If the thermoplastic includes functional groups that react with epoxy groups, then adhesion may be improved, but the shelf life stability of the composition is limited
Solution Approach 1:
The patent incorporates reactive functional groups (such as carboxylic acid groups in polysulfone) that are designed to react with epoxy groups during the curing process rather than during storage. This preliminary preparation of reactive components enables strong adhesion upon curing while maintaining shelf life stability through proper formulation and storage conditions.
Solution Approach 2:
The patent carefully controls the concentration of functional groups and the ratio of reactive components to minimize premature reactions during storage. By optimizing these parameters, the composition maintains stability on the shelf while ensuring adequate reactivity for strong bonding during the curing process.
3Temperature
If the adhesive composition is designed for high temperature use, then the tensile strength at elevated temperature is improved, but the processing by extrusion or injection molding becomes difficult
Solution Approach 1:
The patent employs a composite system of thermoplastic polysulfone and thermosetting epoxy resin. The thermoplastic polysulfone component provides high-temperature stability and processability, allowing extrusion and injection molding at moderate temperatures. Upon curing, the epoxy resin forms a crosslinked network that maintains tensile strength at elevated temperatures up to 150°C or higher.
Solution Approach 2:
The patent optimizes the glass transition temperature (Tg) of the polysulfone component and the curing characteristics of the epoxy system to enable processing at temperatures below the final service temperature. This parameter optimization allows the composition to be molded or extruded and then cured to achieve high-temperature performance.
4Strength
If fiber reinforcement is added to provide stiffness at elevated temperature, then the high temperature performance is improved, but processing of the adhesive composition becomes impossible after impregnating the fibers
Solution Approach 1:
The patent is designed to be applied to fibers before curing, where the uncured composition can be easily impregnated into the fiber structure. The composition maintains its processability during fiber impregnation and then cures in place to provide the required stiffness and high-temperature performance, eliminating the need for post-impregnation processing.
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 allows for effective bonding of metal components in high-temperature applications, maintaining durability under mechanical and environmental stress, and can be processed before curing, offering enhanced tensile strength and stability.
Implementation Method 1
about 7 to about 45 weight percent of one or more high temperature thermoplastic polymers (based on the total weight of the polymeric adhesive composition) having a glass transition temperature of about 175° C. or more
Implementation Method 2
one or more curatives for curing the epoxy resin(s)
Data Source
AI summary
The teachings herein are directed at solid polymeric adhesive compositions for adhering metal components, methods for compounding the polymeric adhesive compositions, articles including a component having the polymeric adhesive composition, methods for producing articles including curing a solid adhesive, and articles including the cured adhesive. Preferred solid polymeric adhesive compositions include a plurality of one or more epoxy resins and one or more polysulfones. In one preferred aspect, the teachings are directed at a stator ring (e.g., for a hybrid motor) including the polymeric adhesive composition for adhering components to a ring.