A method for preparing a multilayer double-angle ultra-thin spread prepreg

Abstract

This invention provides a multi-layer, dual-angle, ultra-thin layup prepreg and its preparation method. It integrates advanced layup theory design concepts with the precision manufacturing process of ultra-thin prepregs, aiming to directly provide a pre-fabricated "multi-layer, dual-angle (e.g., ±Φ, ±Ψ)" ultra-thin layup fiber prepreg. First, two dual-angle ultra-thin layups are prepared as basic units. Then, these basic units are stacked to form a multi-layer, dual-angle ultra-thin layup with a certain even number of layups. This achieves prefabrication and modularization of complex layup designs at the material preparation stage, simplifying the complex layup process of downstream composite material products. It facilitates the use of appropriate multi-layer, dual-angle ultra-thin layup prepregs with the same angle, resulting in composite material products with advantages such as lower interlaminar stress, high damage tolerance, excellent anti-delamination ability, and smoother stress distribution, thus improving the overall performance of the products.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation technology, specifically to a method for preparing multilayer dual-angle ultrathin layup prepreg. Background Technology

[0002] Composite laminates are widely used in high-end equipment fields such as aerospace and transportation, and their performance largely depends on the quality of the prepreg and the layup design. Traditional prepregs are intermediate materials pre-impregnated with fiber bundles or fabrics and a resin matrix (such as epoxy resin). As a "preform" for composite materials, it only requires heating and pressure curing in subsequent molding processes to obtain the final product, significantly reducing the complexity of the molding process. The single-layer thickness of traditional prepregs is typically between 0.1 mm and 0.25 mm.

[0003] Traditional prepreg preparation methods mainly include resin solution method and resin hot melt method. Among them, the resin hot melt method has become the mainstream due to its environmental friendliness, high efficiency, and precise control of resin content. It melts the resin by heating and then impregnates the fibers by precision rolling, which can produce high-quality unidirectional or woven prepregs.

[0004] Traditional prepregs, produced through processes such as autoclaving, compression molding, and vacuum bagging, are widely used in primary or secondary load-bearing components such as aircraft wings, fuselages, satellite structures, and high-end sports equipment. However, their relatively large single-layer thickness imposes significant design limitations: when manufacturing thin-walled or complex curved structures, the number of layers that can be laid is limited, making it difficult to optimize the anisotropic mechanical properties of the structure by finely adjusting the layup angles and sequence. Furthermore, thicker single layers may lead to more frequent initiation and propagation of microcracks within the laminate, affecting damage tolerance, and also resulting in higher interlaminar stress.

[0005] Ultra-thin carbon fiber prepreg generally refers to a single layer thickness of no more than 0.04 mm and a fiber weight per unit area of ​​less than 40 g / m². 2 The core driving force behind its development stems from the extreme pursuit of lightweight structures, high performance, and increased design freedom in fields such as aerospace.

[0006] The preparation of ultrathin prepregs has been a challenge in the industry, mainly due to the following difficulties: large-size ultrathin prepregs are prone to seams, resulting in numerous appearance defects and low yield rates; the use of small-tow fibers leads to low spreading ratios, resulting in high production costs and low efficiency; and the preparation process for high-quality ultrathin prepregs is complex. When preparing structures of a certain thickness, ultrathin prepregs require a large number of layers, increasing manufacturing costs.

[0007] In summary, the development from traditional prepregs to ultrathin prepregs represents a crucial step in the advancement of composite materials, moving from meeting basic structural requirements to achieving ultimate lightweighting, functional designability, and high-end performance. Ultrathinning is not merely a dimensional change; it profoundly impacts the design philosophy, manufacturing processes, and final performance of composite materials, becoming a key direction for material innovation driving technological advancements in aerospace and other fields.

[0008] To overcome these limitations, technological development has primarily evolved in two directions: innovation in layup theory and thinning of prepregs themselves. Regarding layup theory, the aim is to achieve homogenized, single-parameter characterization of composite material stiffness and strength using fewer layup variables, thereby significantly improving design flexibility. In terms of prepreg thinning, the industry has been committed to developing thinner prepregs (e.g., single-layer thickness of 0.02-0.04 mm) to achieve higher damage tolerance and better delamination resistance.

[0009] However, existing technologies typically separate these two paths. Advanced layup theory, in engineering applications, still faces the manufacturing challenges of layer-by-layer layup using traditional thick or single-angle thin prepregs, resulting in cumbersome processes, low efficiency, and the potential for defects introduced by manual handling. Meanwhile, ultrathin prepregs, due to their physical form (extremely thin, prone to adhesion, difficult to handle), significantly increase the complexity and cost of actual layup manufacturing, thus diminishing their theoretical performance advantages. Therefore, the field urgently needs an innovative solution that can integrate advanced layup theory with ultrathin prepreg preparation technology at the front end, fundamentally simplifying the design and manufacturing process and improving the performance and consistency of composite material products. Summary of the Invention

[0010] To overcome the difficulties in designing the layup angle and preparing high-quality prepregs in existing ultrathin prepreg technologies, this invention provides a novel multilayer dual-angle ultrathin layup prepreg composite material technology. This technology prepares high-quality multilayer ultrathin prepregs with good mechanical properties. During the preparation process, the layup angle is preset in advance, and multiple layers (e.g., 12 layers) of ultrathin prepregs with different angles and a thickness of 0.02 mm are prepared together to obtain a multilayer prepreg (e.g., if the number of layers is 12, the thickness of the multilayer prepreg is 0.24 mm).

[0011] This invention provides a method for preparing multilayer ultrathin prepreg, which includes several steps such as selecting the layup angle, preparing a double-layer ultrathin prepreg base unit, and preparing a multilayer double-angle ultrathin layup prepreg. The method produces a high-quality prepreg with a pre-designed layup angle, resulting in excellent mechanical properties of the composite material and simplifying the complex layup process of downstream composite products.

[0012] First, the layup angles are selected. Based on the application conditions of the target composite material, two layup angles, +Φ and -Φ, are chosen. First, a double-layer ultra-thin prepreg base unit is laid. A single layer of ultra-thin prepreg is laid and cut at a +Φ angle to form the initial and supplementary segments of the base layer. Then, a single layer of ultra-thin prepreg adjusted at a -Φ angle is laid on the initial segment, cut and compacted to form a double-layer prepreg base unit. Using the double-layer ultra-thin prepreg base unit with the preset angle combination as the basic unit, it is stacked and compacted on a conveyor belt. The operation is repeated until the predetermined number of layers is reached to obtain a multi-layer double-angle ultra-thin layup fiber prepreg with an even number of layers.

[0013] This invention provides a method for preparing multi-layer, dual-angle ultrathin prepregs. Instead of a single angle, the method proposes a multi-layered ultrathin prepreg. By pre-setting angles to meet different application requirements, angle design is incorporated into the prepreg manufacturing process, reducing the complexity of layup design, improving mechanical properties, and avoiding performance differences caused by non-standard layup angles. Through process control at each step, multi-layer, dual-angle ultrathin prepregs with excellent appearance quality, low production cost, and large dimensions are obtained. Furthermore, composite materials made from these prepregs exhibit excellent mechanical properties.

[0014] The core of this invention, a multi-layer, dual-angle ultrathin layup prepreg, lies in its integration with advanced layup concepts. Instead of using ultrathin unidirectional prepreg as a layup unit in downstream composite material preparation, it leverages raw material design and precise layup angle control to create a multi-layer, dual-angle ultrathin layup prepreg. This improves the production efficiency of downstream composite materials while maintaining the performance of the ultrathin prepreg. Therefore, this invention offers the following advantages: 1. Shift from "solving design problems during manufacturing" to "pre-fabricating manufacturing solutions during design". The problems with traditional / ultra-thin lay-up are all on the manufacturing floor. Using "single-angle, ultra-thin" raw materials to achieve "multi-angle, thick" designs results in a "manufacturing-oriented design" problem.

[0015] The present invention directly provides prefabricated units with "pre-set specific angle combinations and thicknesses (multi-layers)". Designers can use multi-layer, double-angle, ultra-thin prepregs with certain "performance modules" to achieve a paradigm shift of "design-defined manufacturing", which greatly simplifies subsequent layer design.

[0016] 2. Project Feasibility This invention directly pre-fabricates a prepreg of a certain thickness using dual-angle ultra-thin layups. For example, it can be a multi-layer dual-angle ultra-high-strength prepreg containing layup angles of +Φ / -Φ / +Ψ / -Ψ. In use, simply lay several layers of this invention's prepreg, just like laying a traditional single-layer prepreg, to quickly and accurately construct a complete layup structure.

[0017] 3. While retaining the performance advantages of ultra-thin layup, completely overcome its process disadvantages. By fully utilizing the inherent mechanical advantages of ultra-thin layup, such as high damage tolerance, excellent anti-delamination ability, and smoother stress distribution, the prefabrication angle is precisely controlled and the multi-layer consistency is further enhanced.

[0018] The most complex step, "multi-angle precision arrangement," is completed upstream by high-precision prepreg manufacturing equipment, cleverly avoiding the disadvantages of ultra-thin prepreg technology. Downstream users are actually dealing with "composite layers" that have a certain thickness and are ready to use, making the process simpler than with traditional prepregs.

[0019] 4. Achieve significant supply chain and process optimization Firstly, the downstream process is simplified. This reduces the types of ply angles, the number of layups, and the positioning steps, creating more favorable conditions for automated layup.

[0020] Then, the quality and consistency of composite material products are improved. By shifting the control of angular precision from relying on workshop workers to the more controllable raw material production stage, the consistency and controllability of product performance are significantly improved.

[0021] Finally, overall costs can be reduced. Although the unit price of raw materials may rise, the total life cycle cost is expected to decrease by significantly reducing manufacturing time, lowering scrap rates, and reducing tooling complexity. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the preparation method of multilayer dual-angle ultrathin prepreg according to an embodiment of the present invention.

[0023] Figure 2 This is a detailed flowchart of the sub-steps for preparing the two-layer ultrathin prepreg base unit in step S2 of this embodiment of the invention.

[0024] Figure 3 This is a detailed flowchart of the sub-steps for preparing the multilayer ultrathin prepreg in step S3 of this embodiment of the invention.

[0025] Figure 4 This is a top view of the preparation process of multilayer dual-angle ultrathin prepreg according to an embodiment of the present invention.

[0026] Reference numerals in the attached drawings: 1. Initial section of ultra-thin prepreg base layer; 2. Supplementary section of ultra-thin prepreg; 3. Ultra-thin prepreg laying layer; 4. Laying angle of laying layer +Φ; 5. Laying angle of base layer -Φ; 6. Compactor roller; 7. Conveying device. Detailed Implementation

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods have been described herein, any methods similar or equivalent to those described herein may be used in the implementation or testing of this invention.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0030] This invention provides a method for preparing multilayer ultrathin prepreg, comprising: S1, selecting layup angles; S2, preparing a double-layer ultrathin prepreg base unit; and S3, preparing a multilayer double-angle ultrathin prepreg. The core lies in selecting the optimal angle pair, forming a complete double-layer base unit through a "base layer initial segment + supplementary segment" layup strategy, and then stacking these double-layer base units as modules to ultimately obtain a multilayer double-angle (e.g., 12 layers) ultrathin prepreg with a preset angle sequence.

[0031] Step S1: Selecting the ply angle Based on the specific structure, load-bearing conditions, and material system of the target composite material component (such as upper wing, lower wing, fuselage, submarine hull, shaft, wide band mechanism, bulkhead / block, etc.), the two optimal ply angles Φ and Ψ are selected. The preset ply sequence is one of three basic modes, for example: +Φ / -Φ / +Ψ / -Ψ or +Φ / -Ψ / -Φ / +Ψ or +Φ / -Ψ / +Ψ / -Φ. The angle control accuracy is within ±0.5°.

[0032] Step S2: Preparation of double-layer ultrathin prepreg base units (layout without base gaps) With the direction of the transmission device's operation as the 0° reference direction, the operating speed of the transmission device is set to 5-10 m / min.

[0033] S21. Laying the initial section of the base layer: A single-layer ultra-thin prepreg is conveyed and laid on the conveying device at an angle of +Φ. After it covers one edge of the conveying device, it is cut along that edge to obtain the initial section of the base layer. S22, Laying the base layer supplementary section: Immediately following the initial section, continue to convey and cut ultra-thin prepreg laid at the same angle +Φ as the base layer supplementary section. S23. Form a continuous base layer: Repeat the laying of supplementary base layer sections; S24. Laying the initial section of the laying layer: Adjust the single layer of ultra-thin prepreg to the angle -Φ, convey and lay it on the continuous base layer; after it is completely covered, cut it along the edge of the initial section to obtain the initial section of the laying layer. S25, Laying the supplementary section of the laying layer: Following the initial section of the laying layer, continue to convey and cut ultra-thin prepreg laid at the same angle -Φ as the laying supplementary section. S26. Forming a continuous layup layer: Repeatedly lay up additional layup layers; S27. Compaction and Unitization: The drive transmission device moves forward and the compaction roller is used to compact the laying area to form a continuous double-layer ultra-thin prepreg base unit with +Φ / -Φ or +Ψ / -Ψ angle combination. Of course, the laying sequence can be varied according to requirements. Furthermore, due to the special angle, the conveyed ultra-thin prepreg is at a certain angle relative to the conveyor belt. If the base layer and the laying layer are of equal width, there will be areas under the laying layer where the base layer is not laid. Therefore, conveying ultra-thin prepreg again after the initial section of the base layer ensures that there is always a base layer under the laying layer.

[0034] Step S3: Preparation of multi-layer double-angle ultrathin prepreg The double-layer prepreg base unit (angle combination of +Φ / -Φ) obtained in step S27 is used as the basic laying unit.

[0035] S31. Laying a double-layer base unit: Laying a double-layer base unit (such as +Φ / -Φ) as the base layer on the transmission device.

[0036] S32. Laying out a double-layer unit: Lay another double-layer base unit (such as +Ψ / -Ψ) on top of the base layer in an aligned manner.

[0037] S33. Compaction: Interlayer compaction is performed using compaction rollers (temperature 30-40℃) to obtain a prepreg intermediate with four layers having angle combinations of +Φ / -Φ / +Ψ / -Ψ. In this step, the gap of the heated roller press is controlled to be 40-200μm.

[0038] S34. Repeated Stacking: Repeat the stacking and compaction steps described above. For example, stack and compact three four-layer intermediates to obtain a multi-layer, double-angle, ultra-thin plywood prepreg with a total of twelve layers and a total thickness of approximately 0.24 mm. The total number of layers can be a multiple of 2 and n≥4, i.e., 4, 6, 8, 10, 12, etc.

[0039] The aforementioned preparation method has the following key points: Angle accuracy control: The angle control error is controlled within ±0.5° by using a guide roller or laying head driven by a servo motor.

[0040] Continuous production: The actions of conveying devices, cutting, laying, and compaction need to be coordinated and controlled to achieve continuous, rhythmic production. The speed of the conveying device in steps S2 and S3 is 5-10 m / min.

[0041] Material tension control: Precisely control the unwinding and conveying tension of the prepreg to prevent deformation of ultra-thin materials.

[0042] Interlayer bonding: The temperature, pressure, and residence time of the compaction rollers must be matched with the resin system.

[0043] Roller gap control: 10-60 μm for single-layer preparation; 20-120 μm for double-layer preparation; 40-200 μm for four-layer preparation; and 120-250 μm for final compaction of multi-layer preparation.

[0044] The present invention has at least the following beneficial effects: (1) Simplify the downstream manufacturing process. By prefabricating the complex multi-angle layup design at the material end, downstream users only need to lay up a few layers of the prepreg of this invention to build the target structure, which greatly reduces the number of layup layers and significantly improves efficiency.

[0045] (2) Achieving double-layer prepreg with arbitrary ply angle: By using the "base layer initial section + supplementary section" laying method, the technical problem that the upper and lower layers cannot completely overlap when laying two layers of non-equal width prepreg is solved.

[0046] (3) Improve mechanical properties: Based on the angle sequence of ply optimization and combined with the advantages of ultra-thin ply itself, the mechanical properties of the final composite material (such as compression properties, in-plane shear properties, and short beam bending properties) are optimized. Ultra-thin prepreg composite material is superior to conventional prepreg composite material in many properties.

[0047] (4) Overcoming the disadvantages of ultra-thin layup process. Prefabricating the extremely thin single layer into a highly operable multi-layer module significantly reduces the risk of deformation, adhesion and tearing in subsequent layup.

[0048] (5) Appearance and internal quality are controllable. The produced multi-layer ultra-thin prepreg has a smooth appearance, no wrinkles, no visible bubbles, no resin accumulation or poor glue area, and neat edges without defects.

[0049] The ultra-thin layup design of this invention benefits from thinner single layers, requiring cracks to traverse more interfaces during propagation, thereby significantly improving the damage tolerance and interlaminar shear strength of the composite material. The optimized layup angle results in a more uniform stress distribution within the laminate, reducing interlaminar stress concentration. The "modular" prefabrication and the "initial segment + supplementary segment" strategy of the base layer in this invention ensure the accuracy of the layup angle and the integrity of the structure, avoiding the defects introduced by manual layup and fully realizing the theoretical performance.

[0050] The following describes some of the embodiments.

[0051] Example 1 Scenario: Preparation of T800S / 3900 epoxy resin-based composite material for shafts, with the target layup sequence being layup mode one: +54°0 / -54° / +28° / -28° (12 layers in total).

[0052] Prerequisites: Prepare T800S-12K carbon fiber epoxy resin-based ultrathin prepreg, release paper, and kraft paper.

[0053] Specific steps: Pile angle selection: Φ=54°, Ψ=28°.

[0054] Preparation of double-layer prepreg base units: Conveyor belt speed 8 m / min. First, lay an initial section of ultra-thin prepreg at a 54° angle (length L1), followed by an additional section at the same angle (length L2, L1+L2 ensures coverage of the projection of subsequent layers). Then, lay a layer at a 28° angle and compact it with a 35° compaction roller to form a +54° / -54° double-layer base unit. Simultaneously, prepare +28° / -28° double-layer base units in the same manner.

[0055] Multilayer prepreg preparation: A +54° / -54° double-layer base unit was used as the base layer, and a +28° / -28° double-layer base unit was used as the layup layer. After alignment, they were compacted using a 35° compaction roller with a roller gap of 80μm, resulting in a four-layer intermediate body (+54° / -54° / +28° / -28°). Three identical four-layer intermediate bodies were stacked and compacted sequentially, with a final roller gap of 200μm, yielding a total thickness of 0.24mm and an areal density of approximately 360g / m³. 2 12 layers of prepreg.

[0056] Output: Multi-layer double-angle ultra-thin prepreg roll with a width of 500mm, a length of 100m, and an angle sequence of +54° / -54° / +28° / -28°.

[0057] Example 2 Scenario: Preparation of T800S / 3900 epoxy resin-based composite material for submarine hulls, with Φ=16° and Ψ=70° selected.

[0058] Specific steps: Basically the same as in Example 1, but an alternative solution is used to address the edge missing problem: the single-layer prepreg is beveled into parallelogram sheets at 16° and 70° angles, making the width of the base layer sheet larger than the width of the layup layer, and then laid and stacked. This solution has lower material utilization, but is suitable for small-batch production.

[0059] Alternative embodiments In the aforementioned embodiments, +Φ is laid first, followed by -Φ, or -Φ can be laid first, followed by +Φ, thus preparing a -Φ / +Φ double-layer basic unit. As long as each unit contains a pair of layers with opposite angles, the overall effect after stacking is equivalent. Other layup sequences include +Φ / -Ψ, -Φ / +Ψ, -Ψ / +Φ, and +Ψ / -Φ. That is, the two angles Φ and Ψ selected can be any optimized angle pair. The specific stacking order of the double-layer basic unit and the four-layer intermediate can adopt two other basic modes, and the internal order of the double-layer basic unit can also be varied.

[0060] The total number of floors is not limited to 12; it can be a multiple of 2, such as 2, 4, 6, 8, 10, or 12. Additionally, for ease of distinction, a floor with two floors is described as a double-layered floor, but in reality, a double-layered floor is also considered a multi-layered floor.

[0061] The choice of fiber is not limited to carbon fiber; it can also include glass fiber, aramid fiber, etc. The resin can be a thermosetting or thermoplastic resin.

[0062] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing multi-layer, double-angle, ultra-thin layup prepreg, characterized in that, Includes the following steps: S1, ply angle selection; S2, Preparation of double-layer ultrathin prepreg base unit; S3. Preparation of multi-layer double-angle ultra-thin prepreg.

2. The method for preparing multilayer dual-angle ultrathin layup prepreg according to claim 1, characterized in that, In step S1, the layup angle is two angles, Φ and Ψ.

3. The method for preparing multi-layer dual-angle ultra-thin layup prepreg according to claim 1, characterized in that, In step S2, the double-layer ultra-thin prepreg base unit includes a base layer and a layup layer.

4. The method for preparing multi-layer dual-angle ultra-thin layup prepreg according to claim 3, characterized in that, Step S2 specifically includes the following steps: S21. Laying the initial section of the base layer: A single-layer ultra-thin prepreg is conveyed and laid on the conveying device at an angle of +Φ or angle of +Ψ. After it covers one edge of the conveying device, it is cut along that edge to obtain the initial section of the base layer. S22, Laying the base layer supplementary section: Immediately following the initial section, continue to convey and cut ultra-thin prepreg material laid at the same angle +Φ or angle +Ψ as the base layer supplementary section; S23. Form a continuous base layer: Repeat the laying of supplementary base layer sections; S24. Laying the initial section of the laying layer: Adjust the single layer of ultra-thin prepreg to angle -Φ or angle -Ψ, convey and lay it on the continuous base layer; after it is completely covered, cut it along the edge of the initial section to obtain the initial section of the laying layer. S25, Laying the supplementary section of the laying layer: Following the initial section of the laying layer, continue to convey and cut ultra-thin prepreg material laid at the same angle -Φ or angle -Ψ as the laying supplementary section; S26. Form a continuous layup layer: Repeat the layup layer supplementary section.

5. The method for preparing multi-layer dual-angle ultrathin layup prepreg according to claim 4, characterized in that, Step S2 also includes the following steps: S27. Compaction and Unitization: The drive conveyor moves forward and the compaction roller is used to compact the laying area to form a continuous double-layer ultra-thin prepreg base unit with +Φ / -Φ or +Ψ / -Ψ angle combinations.

6. The method for preparing multilayer dual-angle ultrathin layup prepreg according to claim 1, characterized in that, Step S3 specifically includes the following steps: S31. Laying the base unit: Lay a double-layer ultra-thin prepreg base unit with a +Φ / -Φ double angle combination on the conveying device as the base layer; S32. Repeatedly lay the base unit: Lay another double-layer ultra-thin prepreg base unit with +Ψ / -Ψ double angle combination on the base layer in an aligned manner. S33. Compaction: Use compaction rollers to compact the layers to obtain a prepreg intermediate with four layers of angle combination of +Φ / -Φ / +Ψ / -Ψ.

7. The method for preparing multilayer dual-angle ultrathin layup prepreg according to claim 6, characterized in that, When the number of layers is greater than 4, the following steps are also included: S34. Repeated stacking: Repeat the above stacking and compaction steps to obtain a multi-layer double-angle ultra-thin lay-up prepreg with a total number of layers that is a multiple of two and greater than four.

8. The method for preparing multilayer ultra-double-angle thin-layup prepreg according to claim 1, 6, or 7, characterized in that, The angle combination of the four-layer ultra-thin prepreg is +Φ / -Φ / +Ψ / -Ψ or +Φ / -Ψ / -Φ / +Ψ or +Φ / -Ψ / +Ψ / -Φ.

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