Fiber-Reinforced Composite Molded Article Border Adhesion
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Solution Overview
Problem
Existing methods for producing fiber-reinforced composite materials face challenges in achieving sufficient adhesive strength at the border between insert-molded and integrally molded portions, particularly due to irregular interfaces and insufficient impregnation of thermoplastic resin.
Innovation Solution
A method involving the integration of a fiber-reinforced resin substrate with thermoplastic resin and reinforcing fibers, where the fiber volume ratio is optimized to create layers with specific fiber lengths and volume ratios, ensuring that reinforcing fibers are exposed and impregnated to enhance bonding between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fiber-reinforced resin substrate with thermoplastic resin impregnation is used for insert molding, then complex shapes can be produced, but adhesive strength at the border between insert-molded and integrally molded portions is insufficient
Solution Approach 1:
The patent applies local quality by creating distinct zones with different fiber volume ratios and fiber length distributions. The insert-molded portion has a fiber volume ratio of 15-50% while the integrally molded portion has 5-25%, and the border region specifically contains short fibers (0.02-3mm) that bridge the interface. This localized variation in material composition optimizes both the manufacturability of complex shapes and the adhesive strength at critical borders.
Solution Approach 2:
The patent utilizes composite materials by combining thermoplastic resin with reinforcing fibers of different lengths and volume ratios in specific regions. The border region contains a mixture of long fibers (3-100mm) from the insert-molded portion and short fibers (0.02-3mm) from the integrally molded portion, creating a gradient composite structure that enhances interfacial bonding while maintaining the benefits of fiber reinforcement in both zones.
2Ease of manufacture
If thermoplastic resin is injected to integrate with fiber-reinforced composite material, then complex-shaped composite material can be produced, but adhesive strength at the border is insufficient due to irregular interface
Solution Approach 1:
The patent applies parameter changes by systematically varying the fiber volume ratio and fiber length distribution between the insert-molded and integrally molded portions. The fiber volume ratio changes from 15-50% in the insert-molded portion to 5-25% in the integrally molded portion, and fiber length changes from 3-100mm to 0.02-3mm. These controlled parameter variations create a more regular and predictable interface structure that improves manufacturing precision at the border.
3Strength
If fiber volume ratio in resin composition is increased to enhance reinforcement, then mechanical characteristics improve, but impregnation of thermoplastic resin becomes insufficient
Solution Approach 1:
The patent applies local quality by assigning different fiber volume ratios to different regions: 15-50% in the insert-molded portion for high mechanical strength, and 5-25% in the integrally molded portion for adequate resin impregnation. This spatial differentiation allows each region to have optimized properties - the insert-molded portion prioritizes reinforcement while the integrally molded portion ensures sufficient matrix material for bonding.
Solution Approach 2:
The patent uses parameter changes by varying the fiber volume ratio between regions. The lower fiber volume ratio (5-25%) in the integrally molded portion allows better thermoplastic resin impregnation and flow, while the higher fiber volume ratio (15-50%) in the insert-molded portion provides enhanced mechanical reinforcement. This parameter optimization resolves the contradiction between strength and impregnation.
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 method produces a molded article with significantly improved adhesive strength at the border between insert-molded and integrally molded portions, achieving excellent mechanical characteristics and interlaminar shear strength.
Implementation Method 1
reduce the volume in the die to compress the content so that the thermoplastic resin is impregnated into the fiber substrate
Implementation Method 2
a step, which is conducted prior to the above molding step, for exposing reinforcing fibers (x2) on at least a portion of the surface of fiber-reinforced resin substrate (X) by applying heat on a portion of fiber-reinforced resin substrate (X) where no reinforcing fibers (x2) are exposed
Data Source
AI summary
The purpose of the present invention is to obtain a fiber-reinforced composite material molded article having high adhesive strength in a boundary portion between an insert portion comprising a fiber-reinforced resin substrate and an integrally molded portion molded integrally with the insert portion. A fiber-reinforced composite material molded article (1) containing reinforcing fibers and a thermoplastic resin and being provided with a first layer (23), a second layer (22), and a third layer (21) in this order, the thickness of each layer, the ratio of the total volume of reinforcing fibers (x2) having a fiber length of 3 mm to less than 100 mm with respect to the total volume of reinforcing fibers present in the layer, the ratio of the total volume of reinforcing fibers (y2) having a fiber length of 0.02 mm to less than 3 mm with respect to the total volume of reinforcing fibers present in the layer, and the volume content of fibers in each layer being controlled so as to be in specific ranges.