Fiber Reinforced Composite Bonding with Thermoplastic Resin
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Solution Overview
Problem
Current methods for joining fiber reinforced composite materials with thermoplastic resin members lack sufficient impact resistance, resulting in inadequate bonding strength and insufficient integration of these components in molded articles.
Innovation Solution
A molded article is created by integrating a fiber reinforced composite material with continuous reinforcing fibers and a thermosetting matrix resin, joined to a thermoplastic resin member with a rugged interface, where the thermoplastic resin has specific tensile strength, elongation, and impact bonding strength properties, and is composed of polyester resins with polyethylene terephthalate and polybutylene terephthalate components, and optionally includes a portion with radio wave transmittance for electromagnetic shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional joining methods are used to integrate fiber reinforced composite material with thermoplastic resin member, then manufacturing simplicity is maintained, but impact resistance and bonding strength are insufficient
Solution Approach 1:
The fiber reinforced composite material is prepared in advance with a specific surface structure (roughened surface or protrusions) before the joining process. This preliminary surface treatment enables the thermoplastic resin to mechanically interlock with the composite material during injection molding, significantly improving bonding strength without requiring complex post-joining operations or additional joining structures.
Solution Approach 2:
The invention uses a composite joining structure where thermoplastic resin penetrates and bonds with fiber reinforced composite material that has been pre-treated with surface roughening or protrusions. This creates a composite interface combining the mechanical strength of fibers with the bonding properties of thermoplastic resin, achieving high impact resistance and bonding strength through material composition rather than structural complexity.
2Reliability
If simple joining structures are used, then manufacturing ease is maintained, but impact resistance is insufficient
Solution Approach 1:
The fiber reinforced composite material is prepared in advance with a specific surface structure (roughened surface or protrusions) before the joining process. This preliminary surface treatment enables the thermoplastic resin to mechanically interlock with the composite material during injection molding, significantly improving bonding strength without requiring complex post-joining operations or additional joining structures.
Solution Approach 2:
The thermoplastic resin automatically penetrates into the roughened surface or protrusions of the fiber reinforced composite material during the injection molding process itself. The joining action is self-performing through the injection process, eliminating the need for separate joining operations, clamps, or additional manufacturing steps, thereby maintaining ease of manufacture while achieving high impact resistance.
3Strength
If thermoplastic resin with high bonding strength is selected, then impact resistance improves, but manufacturing complexity increases due to specific material requirements
Solution Approach 1:
The invention specifies particular parameter ranges for the thermoplastic resin (tensile strength 25-100 MPa, tensile elongation 200-1000%, melt viscosity 50-500 Pa·s at 250°C) to achieve optimal bonding performance. These parameter specifications ensure high impact bonding strength (3000 J/m² or more) while maintaining manufacturing feasibility. The roughened surface structure of the composite material works synergistically with resins within these parameter ranges, providing both high strength and material selection flexibility.
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 enhances the impact resistance and bonding strength between the fiber reinforced composite material and the thermoplastic resin member, improving the durability and mechanical load resistance of the molded article, particularly in electronic and electronic devices.
Implementation Method 1
the maximum impregnation depth h of the thermoplastic resin (A) in the fiber reinforced composite material (I) is 10 μm or more
Implementation Method 2
a melting point Tm of the polyester resin satisfies an equation, 120°C ≤ Tm ≤ 180°C
Implementation Method 3
a melt viscosity η2 of the polyester resin at a temperature of 250°C is 300 Pa·s or less
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
Disclosed is a molded article composed of a fiber-reinforced composite material (I) containing a continuous reinforcing fiber and a thermosetting matrix resin, and a thermoplastic resin member (II) which is joined to and integrated with at least a part of the surface of the fiber-reinforced composite material (I) by using a thermoplastic resin (A). The joined surface between the thermoplastic resin (A) and the fiber-reinforced composite material (I) has projections and recesses in the cross-section in the thickness direction of the molded article, and the maximum impregnation depth h of the thermoplastic resin (A) in the fiber-reinforced composite material (I) is not less than 10 µm. The thermoplastic resin (A) has a tensile strength at break of not less than 25 MPa and a tensile elongation at break of not less than 200%. The impact adhesive strength at the joined portion of the fiber-reinforced composite material (I) and the thermoplastic resin member (II) is not less than 3,000 J/m2.