Layered Slit Tape Prepreg for Automated Lay-Up Processability
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Solution Overview
Problem
Existing slit tape prepregs used in automated lay-up methods suffer from high tackiness, leading to adhesion issues and decreased processability, and lack sufficient drapability on curved surfaces, especially under varying temperature conditions, affecting the productivity and physical properties of carbon fiber reinforced composite materials.
Innovation Solution
A prepreg structure with a first layer containing carbon fiber and a first epoxy resin composition, and a second layer with a second epoxy resin composition that includes thermoplastic resin and particles, having a specific storage elastic modulus and thermoplastic resin content, reducing resin build-up on guide rolls and ensuring high adhesiveness and drapability over a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the storage elastic modulus of the epoxy resin composition is increased to prevent resin build-up on guide rolls, then resin build-up is reduced, but adhesiveness between slit tape prepregs and tool or between prepregs deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the storage elastic modulus G' within a specific range (5.0×10^5 to 2.0×10^6 Pa at 25°C) and adjusting the viscosity of the epoxy resin composition (100 to 10,000 cP at 25°C). This optimized parameter range prevents resin build-up while maintaining sufficient adhesiveness during automated lay-up processing.
2Object-generated harmful factors
If the temperature is lowered to increase storage elastic modulus and reduce resin build-up, then resin build-up is prevented, but drapability on curved surfaces deteriorates
Solution Approach 1:
The patent uses parameter changes by optimizing the storage elastic modulus G' to within 5.0×10^5 to 2.0×10^6 Pa at 25°C and controlling epoxy resin viscosity to 100-10,000 cP. This balanced parameter range enables the material to maintain adequate drapability on curved surfaces while preventing excessive resin build-up during automated lay-up.
3Reliability
If heating is applied to improve adhesiveness during laying-up, then adhesiveness between prepregs is improved, but resin build-up on guide rolls increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the storage elastic modulus G' within 5.0×10^5 to 2.0×10^6 Pa and viscosity within 100 to 10,000 cP at 25°C. This optimized parameter range allows the material to maintain sufficient adhesiveness during heated laying-up processes while minimizing resin build-up on guide rolls.
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 prepreg design enhances productivity and maintains good physical properties of carbon fiber reinforced composite materials by minimizing resin build-up and improving laminating performance across varying temperatures.
Implementation Method 1
a second layer with a second epoxy resin composition that has dissolved a thermoplastic resin
Implementation Method 2
epoxy resins are in wide use because of their high adhesiveness to carbon fibers
Data Source
AI summary
An object of the present invention is to provide a prepreg having a high processability and laminating performance in an automated lay-up device and serving to produce a cured product having good physical properties, and also provide a method for the production thereof. A prepreg comprising at least the components [A] to [E] listed blow and having a structure incorporating a first layer composed mainly of the component [A] and a first epoxy resin composition that contains the components [B] to [D] but is substantially free of the component [E] and a second layer composed mainly of a second epoxy resin composition that contains the components [B] to [E] and disposed adjacent to each surface of the first layer, the second epoxy resin composition being characterized in that its component [D] accounts for 1 part by mass or more and less than 5 parts by mass relative to the total quantity of its components [B] to [E], which accounts for 100 parts by mass, and also characterized by having a storage elastic modulus G' at 25°C of 8.0 × 105 to 6.0 × 106 Pa as measured at an angular frequency of 3.14 rad/s, giving a value of 0.085 or more as calculated by the equation (1) specified below, and having a component [D] content of 1 part by mass or more and less than 10 parts by mass relative to the total quantity of the first epoxy resin composition and the second epoxy resin composition, which accounts for 100 parts by mass: [A] carbon fiber, [B] epoxy resin, [C] curing agent, [D] thermoplastic resin, and [E] particles containing a thermoplastic resin as primary component and having a volume-average particle diameter of 5 to 50 µm. [Mathematical formula 1] log10G′Paat25°C−log10G′Paat40°C15