Fiber-Reinforced Composite Curing Using Gypsum Die Segmentation
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Solution Overview
Problem
High temperature-curing fiber-reinforced composite materials face issues with resin flow and heat resistance due to viscosity changes during curing, and existing methods using gypsum molding dies are limited by the die's heat resistance and cost, leading to reduced mechanical and heat-resistant properties.
Innovation Solution
A method involving primary curing of a prepreg with an epoxy resin composition containing triphenylmethane-type epoxy, N,N,N',N'-tetraglycidyldiaminodiphenylmethane, and diaminodiphenylsulfone at 110-130°C, followed by secondary curing at 180°C or higher, using a gypsum die for primary curing and then removing the material for free-standing secondary curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high temperature-curing prepregs are used to obtain excellent heat resistance, then heat resistance is improved, but resin flow occurs due to viscosity reduction at high temperature
Solution Approach 1:
The curing process is divided into two distinct stages: first curing at moderate temperature (110-130°C) to establish initial structure and prevent resin flow, then second curing at high temperature (180-200°C) to achieve final heat resistance properties. This segmentation allows each stage to optimize for its specific purpose without the drawbacks of the other.
Solution Approach 2:
The first curing stage at moderate temperature performs preliminary curing before the high-temperature second curing. This preliminary action sets the resin in a stable state that prevents flow during subsequent high-temperature processing, while still allowing the final heat resistance to be achieved.
2Strength
If high temperature-curing is applied to achieve high mechanical properties and heat resistance, then material performance is improved, but molding die heat resistance requirements increase
Solution Approach 1:
The curing process is divided into two distinct stages: first curing at moderate temperature (110-130°C) to establish initial structure and prevent resin flow, then second curing at high temperature (180-200°C) to achieve final heat resistance properties. This segmentation allows each stage to optimize for its specific purpose without the drawbacks of the other.
Solution Approach 2:
The first curing stage acts as an intermediary process that prepares the composite material for the second curing stage. By performing preliminary curing at moderate temperature, it creates a stable intermediate state that enables subsequent high-temperature processing without requiring the molding die to withstand the full high temperature throughout the entire process.
3Ease of manufacture
If moderate temperature-curing prepregs are used for easy molding, then ease of manufacture is improved, but heat resistance of the composite material is reduced
Solution Approach 1:
The curing process continues in two stages rather than stopping at moderate temperature. The first curing at moderate temperature (110-130°C) provides ease of molding, and the second curing at high temperature (180-200°C) continues the useful action of curing to achieve the desired heat resistance, ensuring the process is not interrupted at the suboptimal moderate temperature stage.
Solution Approach 2:
The curing temperature parameter is changed in two stages: first held at moderate temperature (110-130°C) for ease of molding, then increased to high temperature (180-200°C) to achieve the desired heat resistance. This parameter change allows the process to benefit from both moderate and high temperature conditions at appropriate stages.
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
This approach results in fiber-reinforced composite materials with high mechanical properties and heat resistance, suitable for heat-resistant mold and structural materials, while minimizing resin flow issues and optimizing mold material usage.
Implementation Method 1
primary curing at 110-130°C, and then to secondary curing at a temperature which is at least as high as the primary curing temperature
Implementation Method 2
subjecting it to heating or to heating and pressing to cure the thermosetting resin as the matrix resin
Data Source
Figure 1~2
Figure 3
AI summary
A method for producing a fiber-reinforced composite material having high mechanical properties and high heat resistance, and allowing the use of a gypsum die in primary curing, wherein a fiber-reinforced prepreg, obtained by impregnating reinforcing fibers with an epoxy resin composition comprising a triphenylmethane-type epoxy resin, N,N,N',N'-tetraglycidyldiaminodiphenylmethane (B) and diaminodiphenylsulfone (C), is subjected to primary curing at 110-130°C, and then to secondary curing at a temperature which is at least as high as the primary curing temperature.