Thermoplastic Polyimide Composite Melt Processing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for producing reinforcing fiber composite materials using aromatic polyimides face challenges such as poor processability, reliance on high-boiling point solvents, and difficulty in joining layered plates without adhesives, which affects heat resistance and safety.
Innovation Solution
A method involving the mixing of a powder imide oligomer with reinforcement fibers to create uncured layered plates, which are then fused together by heat and pressure without adhesives, using a specific imide oligomer structure and processing conditions to reduce volatile residuals and enhance heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If aromatic polyimide is used as matrix resin for reinforcing fiber composite material, then heat resistance and mechanical characteristics are improved, but processability deteriorates making it unsuitable for melt molding
Solution Approach 1:
The invention changes the chemical structure parameter of the polyimide by introducing flexible spacers (ether groups, carbonyl groups, or siloxane groups) at specific positions in the repeating unit. This structural modification reduces the glass transition temperature from typical high values (250-400°C) to a controlled range of -50°C to 150°C, enabling melt processing while preserving heat resistance above 200°C
Solution Approach 2:
The invention creates a composite molecular structure combining rigid aromatic rings (for heat resistance) with flexible spacer groups (for processability). The repeating unit contains both polyimide segments (providing thermal stability) and flexible spacer segments (enabling melt flow), achieving a synergistic effect that resolves the contradiction between heat resistance and processability
2Ease of operation
If conventional prepreg method using high-boiling point solvent is used, then fiber impregnation is improved, but volatile residuals and safety issues worsen
Solution Approach 1:
The invention extracts and eliminates the high-boiling point solvent (such as NMP) from the conventional prepreg manufacturing process. By using thermoplastic polyimide granules instead of solvent-based varnish, the method achieves complete fiber impregnation through melting and extrusion without leaving any harmful volatile residuals in the final composite material
Solution Approach 2:
The invention replaces the chemical-based impregnation method (solvent penetration) with a physical/mechanical method (melt extrusion and compression). The thermoplastic polyimide is melted, extruded onto fibers under controlled conditions, and then cured to form the composite, eliminating the need for high-boiling point solvents entirely
3Strength
If adhesive is used to join layered plates, then joining strength is improved, but heat resistance and purity deteriorate
Solution Approach 1:
The invention merges the matrix resin function with the adhesive function by using the thermoplastic polyimide matrix itself to bond the layered plates together. The resin-reinforcing fiber composite sheets are joined through heat and pressure without any separate adhesive layer, eliminating contamination while maintaining both joining strength and heat resistance
Solution Approach 2:
The thermoplastic polyimide matrix performs multiple functions simultaneously: it provides structural support, bonds reinforcing fibers together, and acts as the adhesive joining multiple layered plates. This multi-functional approach eliminates the need for separate adhesive materials that would compromise heat resistance
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 allows for the production of reinforcing fiber composite materials with improved heat resistance and reduced volatile content, enabling the creation of complex-shaped molded articles without the need for adhesives, thus simplifying the manufacturing process and ensuring safety.
Implementation Method 1
heating at a temperature at which the plurality of layers stacked are fused together but are not cured
Implementation Method 2
a polyimide capable of a thermal addition reaction is typically used. Such a polyimide is obtained by impregnating fibers with a low-molecular-weight imide oligomer, which is dissolved in a solvent having a high boiling point and is in a state of varnish, and then crosslinking and curing the resin
Data Source
AI summary
A layered body which allows a reduction in residual volatile component and a method for producing the layered body. A reinforcing fiber composite material which has high heat resistance and superior mechanical strength and a method for producing the reinforcing fiber composite material. A method includes fusing together a plurality of layers each of which contains: a powder of an imide oligomer represented by a specific general formula; and reinforcement fibers.