Prepreg Surface Free Energy for Welding Composite Joining
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Solution Overview
Problem
Current fiber-reinforced composite materials face challenges in achieving strong and efficient joining processes, particularly when using thermosetting resins, which result in prolonged production times and reduced material strength due to drilling and adhesive curing processes, and insufficient heat and chemical resistance for high-temperature applications.
Innovation Solution
A prepreg and laminate configuration featuring reinforcing fibers with a surface free energy of 10 to 50 mJ/m2, combined with thermosetting and thermoplastic resins, allowing for improved affinity and joining strength through a Wilhelmy method-controlled surface treatment and compound attachment, enabling welding and reduced production time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical joining methods using bolts, rivets, or screws are used to integrate fiber-reinforced composite materials, then the members can be joined together, but the production process is prolonged and production cost is increased due to preprocessing steps like drilling
Solution Approach 1:
The patent replaces mechanical joining methods (drilling, bolting, riveting) with direct welding of thermoplastic resin members. The thermoplastic resin layer is heated to melt and bond the members together, eliminating the need for mechanical fasteners and preprocessing steps like drilling, thereby reducing production time and process complexity
Solution Approach 2:
The patent utilizes temperature parameter changes to enable joining. The thermoplastic resin layer is heated above its melting point to become molten and form bonds between members, then cooled to solidify the joint. This temperature-based joining process replaces time-consuming mechanical operations
2Ease of manufacture
If joining methods using adhesive are used to integrate fiber-reinforced composite materials, then the members can be joined together, but the production process is prolonged due to bonding preparation, coating, and curing processes
Solution Approach 1:
The patent replaces adhesive bonding processes with direct welding using thermoplastic resin. Instead of applying, coating, and curing adhesive layers, the thermoplastic resin layer is heated to melt and bond members directly, eliminating multiple process steps and reducing production time
Solution Approach 2:
The patent exploits the phase transition of thermoplastic resin from solid to liquid and back. The resin is heated above its melting point to become molten for bonding, then cooled to solidify and form the joint, replacing the chemical curing process of adhesives with a physical phase change process
3Loss of time
If thermoplastic resin is used as matrix for fiber-reinforced composite materials to enable welding, then joining time is shortened, but heat resistance and chemical resistance are insufficient for high-temperature structural applications
Solution Approach 1:
The patent creates a composite material system combining thermosetting resin (for heat and chemical resistance) with thermoplastic resin (for weldability). The thermosetting resin provides the high-temperature structural performance while the thermoplastic resin layer enables efficient welding, achieving both fast joining and high heat resistance through material composition
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 solution enables strong and efficient joining of fiber-reinforced composite materials, reducing production time and costs, while providing excellent joining strength and heat resistance suitable for structural applications like aircraft and automotive components.
Implementation Method 1
reinforcing fibers with a surface free energy of 10 to 50 mJ/m2, combined with thermosetting and thermoplastic resins, allowing for improved affinity and joining strength
Implementation Method 2
the time required for joining the members may possibly be shortened... enabling welding and reduced production time
Data Source
AI summary
An object of the present invention is to provide a prepreg and a laminate for producing a laminate suitable as a structural material, which have excellent joining strength and can be firmly integrated with another structural member by welding. The present invention provides a prepreg including the following structural components: [A] reinforcing fibers, [B] a thermosetting resin, and [C] a thermoplastic resin, wherein [A] has a surface free energy, measured by a Wilhelmy method, of 10 to 50 mJ/m2, [C] is present on a surface of the prepreg, and the reinforcing fibers [A] are present, which are included in a resin area including [B] and a resin area including [C] across an interface between the two resin areas.