Continuous-Belt Prepreg Impregnation Without Backing Sheets
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Solution Overview
Problem
Existing methods for impregnating fibrous materials with thermosetting resin, particularly for prepregs used in wind energy components, result in high material and environmental costs due to the use of backing sheets, resin contamination, and limited control over resin flow and impregnation, which can lead to voids and degraded mechanical properties.
Innovation Solution
A process and apparatus that applies thermosetting resin directly to the fibrous reinforcement material without backing sheets, using continuous belts to heat and impregnate the resin into the fibers, ensuring consistent and high degrees of impregnation through controlled heating and pressure, reducing waste and equipment costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If backing sheets are used to cast resin films, then resin application is simplified and fouling is prevented, but material costs increase and resin contamination occurs
Solution Approach 1:
The patent removes the backing sheet component from the resin application system, extracting the harmful element that causes waste and contamination. Resin is applied directly to the fibrous reinforcement material without requiring a backing sheet carrier, thereby eliminating resin fouling on backing sheets and the associated material losses.
Solution Approach 2:
The patent introduces a belt as an intermediary carrier that replaces the traditional backing sheet. This belt system allows resin to be applied and transferred directly to the fibrous material without the resin contacting and fouling a reusable backing sheet, thus preventing contamination while maintaining the benefits of film casting.
2Loss of substance
If thermosetting resin is applied without backing sheets, then material costs and contamination are reduced, but control over resin flow and impregnation becomes difficult
Solution Approach 1:
The patent controls resin flow and impregnation by adjusting process parameters including temperature, pressure, and belt speed. By heating the resin to controlled temperatures and applying specific pressures during belt transfer, the viscosity and flow characteristics of the thermosetting resin are managed to achieve complete fiber impregnation without excessive resin flow or void formation.
Solution Approach 2:
The resin is pre-heated and pre-conditioned on the belt before being transferred to the fibrous reinforcement material. This preliminary action ensures the resin reaches the optimal temperature and viscosity state for controlled impregnation, preventing uncontrolled flow during the actual impregnation process.
3Productivity
If high temperature is applied to thermosetting resin, then impregnation speed increases, but early onset of curing occurs
Solution Approach 1:
The patent applies heating in a controlled, periodic manner through the belt system, with distinct heating zones followed by impregnation zones. The resin undergoes controlled temperature elevation in stages, allowing impregnation to proceed at elevated temperatures without sustained heat exposure that would trigger premature curing. The process cycles through heating, impregnation, and cooling phases.
Solution Approach 2:
The continuous belt system provides uninterrupted, controlled heating and impregnation in a single continuous operation. The resin remains in motion throughout the process, preventing localized overheating and ensuring uniform temperature distribution. This continuous action allows sustained elevated temperatures for impregnation without the dwell time required for curing to initiate.
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
Achieves consistent and high resin impregnation with reduced material and operational costs, minimizing resin waste and contamination, and improving the mechanical properties of the final cured parts.
Implementation Method 1
heating the layer of first thermosetting resin matrix applied to the first surface of the layer of reinforcement fibre in contact with the support surface of the first continuous belt
Implementation Method 2
compressing the layer of first thermosetting resin matrix and the layer of reinforcement fibre between the support surfaces of the first and second continuous belts so that the first thermosetting resin matrix impregnates the layer of reinforcement fibre
Data Source
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AI summary
There is provided a process for preparing a prepreg (31) comprising reinforcement fibre (13) impregnated with a thermosetting resin matrix (20), said process comprising: a) providing a layer (24) of reinforcement fibre (13); b) applying a layer (24) of a first thermosetting resin matrix (20) to the first surface (15) of the layer (24) of reinforcement fibre (13) and bringing the first surface (15) of the layer (24) of reinforcement fibre (13) into contact with the support surface (5) of a first continuous belt (3), so that the layer (24) of first thermosetting resin matrix (20) is positioned between, and in contact with, the first surface (15) of the layer (24) of reinforcement fibre (13) and the support surface (5) of the first continuous belt (3); c) heating the layer (24) of first thermosetting resin matrix (20) applied to the first surface (15) of the layer (24) of reinforcement fibre (13) in contact with the support surface (5) of the first continuous belt (3); d) bringing the second surface (17) of the layer (24) of reinforcement fibre (13) into contact with the support surface 9) of a second continuous belt (7); e) heating the layer (24) of first thermosetting resin matrix (20) and the layer (24) of reinforcement fibre (13) between the support surfaces of the first and second continuous belts (3, 7) so that the first thermosetting resin matrix (20) impregnates the layer (24) of reinforcement fibre (13); f) cooling the layer (24) of reinforcement fibre (13) impregnated with the first thermosetting resin matrix (20) between the support surfaces of the first and second continuous belts (3, 7); and g) removing the layer (24) of reinforcement fibre (13) impregnated with the first thermosetting resin matrix (20) from the support surfaces of the first and second continuous belts (3, 7).