Fiber-reinforced thermoplastic prepreg tape and in-situ forming method and application thereof

Abstract

The invention discloses a fiber-reinforced thermoplastic prepreg tape as well as an in-situ forming method and application thereof, and belongs to the field of manufacturing of high-performance composite materials. The method comprises the following steps: activating the to-be-treated surface of a fiber-reinforced thermoplastic prepreg tape base material, and heating to a set temperature below the melting point of matrix resin; uniformly spraying composite resin powder containing matrix resin powder and functional additive powder on the heated surface; and finally, hot-pressing fusion is conducted through a heating type extrusion roller set, the powder is fused and combined through the instantaneous temperature gradient, rapid cooling and shaping are conducted by means of the heat sink effect of the prepreg tape body, and therefore the functionalized gradient interface structure is constructed on the surface of the prepreg tape. According to the invention, the interlaminar shear strength and in-plane shear strength of a composite material product can be improved, the porosity is greatly reduced, and the industrial problems of excessive interlaminar pores and insufficient binding force during automatic laying caused by surface defects of the prepreg tape are effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to high-performance composites, in particular a kind of fiber-reinforced thermoplastic prepreg tape and its in-situ forming method and application. BACKGROUND

[0002] High-performance thermoplastic resin-based composites, such as carbon fiber-reinforced polyether ether ketone (CF / PEEK) and carbon fiber-reinforced polyphenylene sulfide (CF / PPS), are favored in the fields of aerospace, petrochemical and other high-end equipment manufacturing due to their excellent toughness, recyclability, unlimited storage period and efficient in-situ forming capability. Automatic fiber placement (AFP) and automatic tape laying (ATL) processes are key technologies for efficient manufacturing of large components.

[0003] However, the laying-grade thermoplastic prepreg tape that truly meets the requirements of automatic laying process is still a rare product in the current market. The core problem lies in that the high melt viscosity of thermoplastic resin leads to difficult fiber impregnation, and the prepared prepreg tape generally has high porosity (usually ≥5%), uneven surface resin distribution, and fiber exposure, etc. These surface defects dynamically form a large number of micron-sized "air pockets" during the laying process. These interlaminar voids are difficult to effectively eliminate during subsequent forming, and are ultimately frozen inside the composite, resulting in weak interlaminar bonding, which is specifically manifested as significantly insufficient interlaminar shear strength (ILSS) and in-plane shear strength.

[0004] Prior art (such as: Chinese patent publication No. CN103158209A, published on June 19, 2013, invention patent application with the title of "A method for preparing continuous carbon fiber reinforced thermoplastic prepreg tape", Chinese patent publication No. CN102417600A, published on April 18, 2012, invention patent application with the title of "A method for preparing continuous carbon fiber reinforced thermoplastic resin composite") has always been committed to optimizing the bulk impregnation process of resin and fiber to reduce overall porosity, but has failed to effectively solve the problem of interlaminar voids dynamically generated during the laying process due to surface microscopic quality defects of prepreg tape. Although the technology increases the surface resin content by scattering a single matrix resin powder, due to its consistent viscosity with the bulk, it is difficult to fully flow and fill the voids within the short forming window, and has no interface toughening effect, and the performance improvement is bottlenecked. SUMMARY

[0005] The purpose of the present application is to solve the problem of poor interlaminar bonding of composite materials caused by the poor surface quality of fiber-reinforced thermoplastic prepreg tape in the automatic laying process, and to provide a fiber-reinforced thermoplastic prepreg tape in-situ forming method. By constructing a functional gradient interface structure on the surface of the prepreg tape, it can actively flow and fill the interlaminar gap in the subsequent automatic laying process, thereby significantly improving the interlaminar shear strength and in-plane shear strength of the composite material and greatly reducing the porosity. The present application also discloses a fiber-reinforced thermoplastic prepreg tape prepared by the above-mentioned fiber-reinforced thermoplastic prepreg tape in-situ forming method.

[0006] The purpose of the present application is mainly realized by the following technical solutions: A fiber-reinforced thermoplastic prepreg tape in-situ forming method, comprising the following steps: Step S1, activating the surface of the fiber-reinforced thermoplastic prepreg tape substrate to be treated to improve the surface activity; Step S2, heating the fiber-reinforced thermoplastic prepreg tape substrate to be treated to make the surface temperature T1 meet: Tm-80℃ ≤ T1<Tm; wherein Tm is the melting point of the matrix resin in the fiber-reinforced thermoplastic prepreg tape substrate; Step S3, uniformly sprinkle the composite resin powder on the surface of the heated fiber-reinforced thermoplastic prepreg tape substrate to be treated to form an initial powder layer with a thickness of 8~30µm; wherein the composite resin powder contains 90~99.5wt% of main resin powder and 0.5~10wt% of functional additive powder, the material of the main resin powder is the same or compatible with the matrix resin in the fiber-reinforced thermoplastic prepreg tape substrate, and the functional additive powder is any one or two or more mixtures of high flowability resin, maleic anhydride grafted interface compatibilizer, and core-shell structure polymer toughening agent; Step S4, passing the fiber-reinforced thermoplastic prepreg tape substrate with the initial powder layer through the nip of the heated extrusion roller set, under the combined action of heat and pressure, the initial powder layer melts and fuses with the surface resin of the fiber-reinforced thermoplastic prepreg tape substrate to be treated, and after leaving the nip, the in-situ formed fiber-reinforced thermoplastic prepreg tape product is obtained based on the heat sink effect; wherein the heating temperature of the heated extrusion roller set is T2, Tm ≤ T2 ≤ Tm+60℃.

[0007] High performance thermoplastic resin matrix composites are favored in the field of high-end equipment manufacturing such as aerospace and petrochemical industry due to their excellent comprehensive performance. Compared with traditional thermosetting composites, the advantages of thermoplastic composites are as follows: 1) the mechanical properties of the welding points are high because of the melt welding; 2) the damage tolerance is excellent and the adaptability to harsh environment is strong; 3) the molding process is reversible and the defects can be repaired online; 4) the hygroscopicity is low and the design allowance is reduced; 5) the composites can be stored at room temperature for an indefinite period of time without the need for refrigeration equipment, thus reducing the storage cost; 6) the composites have excellent temperature resistance and can be recycled, thus being green and environmentally friendly. However, the thermoplastic prepreg tapes that can meet the requirements of automatic fiber placement (AFP) and automatic tape laying (ATL) processes are still rare in the current market. Firstly, the viscosity of thermoplastic resin is high and the flowability is low, which makes it difficult to impregnate the resin and the reinforcing fibers, and thus the porosity of the prepreg tape is high, the fiber and resin distribution is uneven, the surface thickness is uneven, and there are defects such as fiber exposure and resin tumor. Secondly, more difficultly, the micro quality defects (such as exposed fibers and uneven resin distribution) on the surface of the prepreg tape will cause a large number of micron-sized “air pockets” between the layers at the moment of laying. These dynamic pores are difficult to effectively remove during the molding process and are finally frozen in the interior of the composite, becoming a weak link of the interlaminar performance.

[0008] The prior art, such as the invention patent application with the invention name of "a method for preparing continuous carbon fiber reinforced thermoplastic prepreg tape" disclosed in the background section of the present application, patent number CN103158209A, published on June 19, 2013, uses a melt impregnation method, and the carbon fiber is impregnated with molten thermoplastic resin through an impregnation roller, and then the resin content is adjusted by a resin adjusting roller. However, due to the high viscosity of the thermoplastic resin, it is difficult for the carbon fiber to be fully impregnated, and the porosity of the prepared continuous carbon fiber reinforced thermoplastic prepreg tape is usually more than 5% (part even reaches 8%~10%), and the hot melt method leads to rough surface of the prepreg tape, uneven resin distribution, thickness deviation more than 10%, and obvious surface quality defects. The invention patent application with the invention name of "a method for preparing continuous carbon fiber reinforced thermoplastic resin composite material" disclosed in the background section of the present application, patent number CN102417600A, published on April 18, 2012, adds insoluble thermoplastic powdery resin to polyether sulfone solution to prepare a suspension, and the product is obtained by hot pressing. However, this method needs to use toxic organic solvents, and the powder amount is difficult to control accurately. At the same time, the boiling point of the organic solvent is high, and bubbles will be generated in the prepreg tape during the volatilization process, resulting in porosity rising to more than 5%. The prepreg tapes prepared by the above prior art do not have a special surface functional structure designed to actively exhaust, and the interface gap caused by uneven surface resin distribution is dynamically formed. Simply increasing the amount of resin cannot effectively solve this problem, resulting in generally low interlaminar bonding force, which cannot meet the requirements of automatic laying process on interlaminar shear strength. Therefore, there is an urgent need in the art for a new technical idea, not only focusing on bulk impregnation, but also focusing on active interface engineering design of the prepreg tape surface, to fundamentally solve the dynamic interlaminar porosity problem in the laying process.

[0009] In summary, the prior art has always been committed to optimizing the impregnation process of resin and fiber to reduce the overall porosity, but has failed to effectively solve the interlaminar porosity problem dynamically generated in the lamination process due to the microscopic quality defects on the surface of the prepreg tape. Currently, there is no technical report on fundamentally improving the interlaminar bonding force by constructing a surface functional layer that can actively adapt and fill the interfacial gap. Although the content of surface resin can be increased to a certain extent by scattering single matrix resin powder, practice shows that there is a bottleneck in the effect of improving interlaminar performance. The reason is that after the single resin powder is melted, its viscosity and flowability are completely consistent with the body resin of the prepreg tape, and it is often difficult to flow and completely fill the microscopic pores within a short molding window. In addition, there is no additional improvement in the interfacial compatibility and toughening effect of the body resin. Therefore, the present application innovatively proposes the use of a specific ratio of composite resin powder to construct a functional surface layer. The composite resin powder system takes the same or compatible resin powder as the main body of the matrix resin of the prepreg tape, aiming to ensure good thermodynamic compatibility and molecular chain diffusion and fusion ability between the functional layer and the body. On this basis, the present application precisely introduces 0.5% to 10% of functional additive powder, aiming to solve specific technical problems in the interfacial fusion process: (1) When introducing high-flowability resin powder, the present application can significantly reduce the melt viscosity of the functional layer material at the molding temperature, giving it excellent spreading and permeability, thereby actively and efficiently filling the interlaminar microscopic pores. (2) When introducing maleic anhydride grafted compatibilizer, the active groups (anhydride) can react with the polar functional groups on the surface of the carbon fiber and the resin molecular chain, greatly strengthening the interfacial chemical bonding between the functional layer / fiber and the functional layer / body resin, and fundamentally improving the interfacial strength. (3) When introducing a core-shell structured polymer toughener, a microscopic toughening structure can be formed inside the functional layer, inducing energy dissipation mechanisms such as crazing and shear banding when subjected to interlaminar stress, significantly improving the damage tolerance and interlaminar toughness of the composite material, and preventing the propagation of interfacial cracks.

[0010] In the preparation of the fiber-reinforced thermoplastic prepreg tape, after hot pressing and fusion, the initial powder layer is densified to form a functional surface layer that is tightly combined with the body of the prepreg tape. Since in the extrusion gap, the melted powder will flow and fill the microscopic depressions on the surface of the prepreg tape under pressure, and partially diffuse with the surface layer matrix resin, the thickness of the functional layer formed will usually be slightly less than the average thickness of the initial powder layer.

[0011] The thickness of the initial powder layer of the present application is controlled at 8-30 µm to ensure that there is sufficient powder material to form a continuous and dense functional surface layer after hot pressing fusion. If the initial powder layer is too thin (e.g. less than 8 µm), it is difficult to form a complete functional layer; if it is too thick (e.g. more than 30 µm), it will lead to uneven melting, rising costs, and may affect the overall performance of the composite material. The present application provides sufficient powder material to ensure the formation of a continuous and dense functional surface layer, and also provides sufficient material for powder melting, flow and filling of the microscopic depressions on the substrate surface.

[0012] In the specific implementation of the present application, if T1 is too low, the resin is still strong and rigid, the powder is difficult to embed and adhere, and it is easy to fall off during transportation; if it reaches or exceeds Tm, the surface layer resin will melt and flow, the powder will sink into it or be unevenly wrapped, and it will not be able to form an independent and uniform initial powder layer, which will destroy the process basis. The present application heats the activated fiber-reinforced thermoplastic prepreg tape substrate through step S2, and the powder particles can partially embed in the softened resin surface layer to form a microscopic mechanical interlock, ensuring the stability of adhesion during transportation and providing a uniform material basis for subsequent hot pressing. The present application limits Tm-80℃ ≤ T1<Tm, which is based on a comprehensive consideration of the softening behavior of different types of thermoplastic resins. For example, semi-crystalline resins such as polyether ether ketone (PEEK) have a more obvious softening closer to Tm, but preheating in the interval of Tm-50℃ to Tm-80℃ can still achieve basic adsorption of the powder through softening of the amorphous region. In the specific implementation of the present application, the optimal T1 temperature point can be selected through conventional experiments within the wide window of Tm-80℃ to Tm according to the specific resin system, powder characteristics and final performance requirements. If T2 is too low, the melt viscosity is still very high, the flow and diffusion are slow, and it is difficult to achieve complete melting of the powder and sufficient molecular chain entanglement with the matrix resin within the short roller gap residence time; if T2 is too high, the high temperature may cause thermal oxidative degradation of part of the high-performance resin, which will damage the performance, and will lead to a decrease in melt viscosity, and an excessively low melt viscosity will cause the functional layer resin to excessively penetrate into the prepreg tape body fiber bundle, consuming its ability to fill the interlayer pores, and possibly damaging the fibers. The present application limits Tm ≤ T2 ≤ Tm+60℃, so that the contact surface melts instantaneously, and the low-temperature prepreg tape body acts as a "heat sink" to quickly cool and set the material after leaving the roller gap, thereby "freezing" the gradient interface structure formed by melting and diffusion, preventing structural relaxation or damage due to long-term high temperature.

[0013] The synergistic setting of T1 and T2 parameters in the application constructs a precise "stepped" thermal strategy, the core of which is: by strictly controlling the preheating temperature T1 below the melting point of the resin (Tm-80℃ ≤ T1<Tm), the surface resin of the prepreg tape is fully softened into a "sticky bed", thereby ensuring that the subsequent falling composite powder can be firmly attached and not sink into the flowing resin, laying a uniform and stable material basis for the construction of the functional layer; at the same time, the hot pressing temperature T2 is set in the range not lower than the melting point (Tm ≤ T2 ≤ Tm+60℃), which provides sufficient overheating energy to ensure that the powder and the surface resin can be instantaneously and completely melted and achieve sufficient molecular chain diffusion and fusion within a very short roll gap contact time. This combination of temperature parameters systematically solves the process contradictions of "stable powder adhesion", "full interface fusion" and "rapid structure locking", and is the key to realizing the high-performance, low-porosity gradient interface structure.

[0014] The application limits the proportion of functional additive powder in the composite resin powder to 0.5-10wt%, which is obtained through repeated experiments and summary by the inventors. The lower limit of 0.5% ensures that the functional additive can reach an effective concentration, which is sufficient to form a continuous network or interface in the functional layer, and effectively plays the role of improving fluidity, enhancing adhesion or toughening. The upper limit of 10% effectively prevents the risks that may be caused by excessive additives, such as excessive change of the intrinsic properties of the functional layer, damage to the compatibility of the functional layer with the prepreg tape matrix resin, or imbalance of the performance of the functional layer itself.

[0015] Further, the activation treatment of the fiber-reinforced thermoplastic prepreg tape substrate in step S1 is realized by using a corona treatment instrument or an atmospheric plasma torch. When the corona treatment instrument is used for activation treatment, the power of the corona treatment instrument is 200-1000W, and the treatment speed is 1-10m / min. The application limits the lower limit of the power of the corona treatment instrument to 200W, so as to ensure that the discharge intensity is sufficient to effectively ionize air, generate sufficient plasma on the surface of the rapidly moving tape, and reliably improve the surface energy, preventing uneven or ineffective activation caused by insufficient power. The upper limit of the power (1000W) is to avoid the excessive etching, thermal damage or even breakdown of the surface resin of the prepreg tape that may be caused by excessive energy, and to ensure the safety of the treatment process and the integrity of the material intrinsic properties. The lower limit of the treatment speed of the corona treatment instrument (1m / min) provides sufficient energy action time for difficult-to-process material systems (or when the ultimate effect is pursued). The upper limit of the speed (10m / min) directly matches the rigid demand for high efficiency of industrialized continuous production, ensuring that the process has practical application value.

[0016] Further, the high-fluidity resin uses at least one of polyetherimide, polyether sulfone or low molecular weight polyether ether ketone.

[0017] The maleic anhydride grafted interface compatibilizer adopts at least one of maleic anhydride grafted polyetherimide and maleic anhydride grafted styrene-ethylene-butylene-styrene copolymer. The core-shell structure polymer toughening agent adopts at least one of methyl methacrylate-butadiene-styrene copolymer, acrylate core-shell copolymer and silicone-resin composite core-shell polymer.

[0018] Further, the median particle size D50 of the composite resin powder is 5-30 µm. When the particle size of the composite resin powder is too fine, the powder is prone to agglomeration, and the agglomerated powder may not be completely melted and dispersed during hot pressing; when the particle size of the composite resin powder is too coarse, it is difficult to form a thin functional layer with uniform thickness and density, and the rough surface will weaken the effect of filling interlayer pores. The present application limits the median particle size D50 of the composite resin powder to 5-30 µm, which can overcome the agglomeration tendency, ensure uniform and continuous powdering, and easily form an initial powder layer with controllable thickness and smoothness; under the set heating temperature (T2) and instantaneous hot pressing conditions, rapid and complete melting can be achieved, thereby fully diffusing and fusing with the resin on the surface of the prepreg tape to form a compositionally continuous gradient interface structure.

[0019] Further, the heating temperature T2 of the heating type extrusion roller group in step S4 is ≥ T1+10℃. In this way, in the specific implementation of the present application, the high temperature difference (T2≥T1+10℃) intentionally maintained between T2 and T1 forms a strong directional temperature gradient at the moment of hot pressing, which not only drives the fusion process, but also enables the prepreg tape body to act as an efficient "heat sink" to promote rapid cooling and setting of the functional layer material after the material leaves the nip, thereby "freezing" and fixing the ideal gradient interface structure.

[0020] Further, the steps S1 to S4 are realized based on a fiber-reinforced thermoplastic prepreg tape in-situ forming system, which comprises, in sequence along the conveying direction of the fiber-reinforced thermoplastic prepreg tape substrate, a unwinding device, a prepreg tape surface activation processor, a heater, a powdering device, a heating type extrusion roller group, a traction roller group and a winding device; the process of the fiber-reinforced thermoplastic prepreg tape in-situ forming method realized by the fiber-reinforced thermoplastic prepreg tape in-situ forming system is as follows: The fiber-reinforced thermoplastic prepreg tape substrate is unwound from the unwinding device, and the untreated surface of the fiber-reinforced thermoplastic prepreg tape substrate is activated by the prepreg tape surface activation processor, the activated fiber-reinforced thermoplastic prepreg tape substrate is heated by the heater, the composite resin powder is uniformly scattered on the heated surface of the fiber-reinforced thermoplastic prepreg tape substrate by the powdering device, and the heating type extrusion roller group is used for hot pressing and fusion, and then the in-situ formed fiber-reinforced thermoplastic prepreg tape product is obtained by heat sinking and cooling, and then conveyed to the winding device by the traction roller group for winding.

[0021] Further, the heating type extrusion roller set comprises a heating top roller for heating the surface of the fiber reinforced thermoplastic prepreg tape substrate on which the initial powder layer is sprayed, and a supporting bottom roller arranged below the heating top roller, the area between the heating top roller and the supporting bottom roller is a nip, the nip height is less than the total thickness of the fiber reinforced thermoplastic prepreg tape substrate and the powder layer passing therethrough, and the compression ratio is 5% to 30%; and the linear pressure of the heating type extrusion roller set is 10 to 25 kg / cm.

[0022] The compression ratio is limited to 5% to 30%, and the lower limit of 5% ensures that the initial loose powder layer is compacted as necessary, drives away the air between the particles, and becomes dense, providing a uniform material basis for subsequent melting; if the compression ratio is too low, the compaction is insufficient, and there are many residual pores in the powder layer. The upper limit of 30% strictly prevents excessive compression, avoids damaging the fiber structure in the prepreg tape substrate or excessively extruding the resin inside, and thus reliably protects the mechanical properties of the prepreg tape body from being damaged. The linear pressure is limited to 10 to 25 kg / cm, which cooperates with the temperature (T2) to directly control the interface fusion quality in the molten state. The lower limit of 10 kg / cm provides sufficient force to promote the transverse flow of the molten low-viscosity functional layer resin, fully spread and penetrate into the microscopic depressions on the surface of the prepreg tape, and realize close physical adhesion and chemical diffusion; insufficient pressure will result in incomplete fusion interface and weak adhesion. The upper limit of 25 kg / cm avoids excessive extrusion of the molten resin due to excessive pressure, excessive unevenness of the functional layer thickness, and even damage to the good interface structure formed. The compression ratio mainly controls the macroscopic thickness change and initial densification, and the linear pressure mainly controls the microscopic flow and interface bonding in the molten state. The combination of the two ensures that the loose powder is converted into a functional gradient surface layer with controllable thickness, firm interface, and dense interior through appropriate mechanical action without damaging the substrate.

[0023] The fiber reinforced thermoplastic prepreg tape prepared by the above-mentioned in-situ forming method has a functional surface layer on at least one surface of the prepreg tape, the functional surface layer is formed by melting of the composite resin powder, and the functional surface layer and the prepreg tape body form a continuous interface structure without delamination through a diffusion transition layer; wherein the diffusion transition layer is an interface compatible zone formed by mutual diffusion and molecular chain entanglement of the functional surface layer and the matrix resin of the prepreg tape body under the action of heat and pressure.

[0024] The functional surface layer, diffusion transition layer and prepreg tape body of the present application form a "functional gradient interface structure", which is not a simple physical coating, but a microscopic region that continuously changes in composition and performance from the surface to the inside. The structure presents a three-layer continuous transition system in the microstructure: (a) The outermost layer (functional surface layer): a continuous resin-rich layer with substantially no reinforcing fibers, formed by melting of the composite resin powder. This layer can melt first and flow actively under the action of external pressure during the hot-pressing of the composite material layer forming, and its core function is to adaptively fill the interlayer micro-gaps and exhaust channels dynamically generated due to the microscopic unevenness of the pre-impregnated tape surface.

[0025] (b) The middle layer (diffusion transition layer): an interfacial compatible zone formed by the mutual diffusion and molecular chain entanglement of the functional surface layer resin and the pre-impregnated tape body matrix resin under the action of hot-pressing. This layer ensures the formation of a continuous interface without delamination between the functional surface layer and the pre-impregnated tape body, and is the key to achieving high interfacial bonding strength.

[0026] (c) The inner layer (pre-impregnated tape body): the original pre-impregnated tape structure containing reinforcing fibers and matrix resin.

[0027] There is no obvious macroscopic interface between the three layers, and the resin composition, fiber content and performance (such as modulus) show a continuous gradient change.

[0028] Due to the difficulty of impregnation, traditional thermoplastic pre-impregnated tapes have defects such as exposed fibers, uneven resin distribution, and microscopic depressions on the surface. When two pre-impregnated tapes are stacked together for layering, their surfaces cannot completely adhere to each other, forming a large number of micron-scale, interconnected, winding gullies and cavities. These cavities are trapped air - "air pockets". During hot-pressing, the pre-impregnated tape body resin melts, but its viscosity is extremely high and its flowability is poor. It acts like a viscous dam, quickly surrounding and sealing the entrances of these microscopic gullies, making it difficult for the internal air to find an effective path to escape under the limited molding time and pressure, and ultimately being "frozen" inside the composite material, forming pores.

[0029] When the fiber reinforced thermoplastic prepreg tape of the application is used to prepare a composite product, the functional surface layer will melt earlier and more easily than the high-viscosity prepreg tape body resin during hot pressing, forming a resin front with significantly lower viscosity. The functional surface layer is a continuous resin-rich layer with essentially no reinforcing fibers, which covers the surface of the prepreg tape and fills in the original microscopic depressions. When the functional surface layers of two prepreg tapes come into contact, the interface between them is no longer a "complex terrain" full of ravines, but a relatively flat, low-viscosity resin plane. At the beginning of hot pressing, the low-viscosity functional surface layer resin will flow laterally under external pressure, flowing into and filling any microscopic gaps that may form when the two prepreg tapes come into contact, "displacing" the air from these locations. More importantly, this flowing resin forms a continuous, interconnected network between the layers, allowing trapped air to be more easily pushed towards the edges of the laminate and expelled. Because the functional surface layer resin has low viscosity and good flowability, it can maintain sufficient flowability before the external pressure disappears, allowing the "air vent channel" to remain open for a much longer time than if the high-viscosity body resin were to seal it off, thus providing a valuable time window for air venting. The molten low-viscosity functional surface layer resin will flow laterally in the interlayer plane under pressure, driving trapped air bubbles forward. When the air is vented, the flowing resin immediately occupies and fills the space originally occupied by the air, achieving "seamless connection". Finally, when the entire interface is completely filled with functional surface layer resin and merged with its body resin, a dense and pore-free interface layer is formed. By creating a low-viscosity, easily flowing resin front between the layers, the application dynamically drives and replaces air, thus preventing the formation of pores from the source. This unique gradient structure enables the active venting and gap filling of the molding process, fundamentally solving the problem of weak interlaminar bonding caused by dynamic interlaminar pores.

[0030] Further, the thickness of the functional surface layer is 5-20 microns.

[0031] A composite product is prepared using the above fiber reinforced thermoplastic prepreg tape through winding or automatic laying process.

[0032] The application aims to overcome the inherent problem of fiber reinforced thermoplastic prepreg tape during layering: excessive interlaminar pores leading to weak interlaminar bonding of composite materials, specifically manifested as significantly insufficient in-plane shear and interlaminar shear strength. The innovative solution is to construct a functional gradient interface structure in situ on the surface of the prepreg tape, which can actively flow and fill the interface microscopic gaps during the molding process, thereby preventing and even eliminating interlaminar pores from the source.

[0033] Compared with the prior art, the present application has the following beneficial effects: (1) The present application provides a prepreg tape with a functional gradient interface structure on the surface and a preparation process thereof. Through a series of innovative processes such as surface activation, composite powder scattering, and precise hot pressing fusion, a controllable functional layer that can actively adapt to and fill the interfacial gap is constructed on the surface of the prepreg tape. The problems of high porosity (≥5%), uneven distribution of surface resin, insufficient interlaminar bonding force, etc. in the prior art are solved. The preparation process does not require toxic solvents, the thickness and morphology of the functional surface layer can be precisely controlled, and it can be directly applied to automatic laying process, greatly reducing the production time of composite materials and fully utilizing the high production efficiency of thermoplastic composites.

[0034] (2) The functional surface layer in the fiber-reinforced thermoplastic prepreg tape of the present application is a resin-rich layer without reinforcing fibers. During the hot pressing process of the automatic laying process, the functional surface layer has excellent flowability, can actively fill the dynamic interlaminar pores generated during laying, and can improve the in-plane shear strength and interlaminar shear strength, and reduce the porosity.

[0035] (3) The present application constructs a gradient interface structure, which presents a three-layer continuous transition system of "resin-rich layer-diffusion transition layer-prepreg tape body" in microcosm, realizes continuous gradient change in composition and performance from surface to inside, and ensures high interfacial bonding strength. BRIEF DESCRIPTION OF DRAWINGS

[0036] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings: Figure 1 is a flow chart of the in-situ forming method of the present application; Figure 2 is a schematic diagram of the in-situ forming system of the fiber-reinforced thermoplastic prepreg tape of the present application.

[0037] In the drawings, the names corresponding to the reference numerals are: 1, unwinding device, 2, prepreg tape surface activation processor, 3, heater, 4, powder sprayer, 5, heated extrusion roller group, 6, traction roller group, 7, winding device. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with embodiments and drawings. The illustrative embodiments of the present application and their descriptions are only used to explain the present application and do not constitute a limitation on the present application.

[0039] As shown in Figure 1 , an in-situ forming method of a fiber-reinforced thermoplastic prepreg tape, comprising the following steps: Step S1, the surface of the fiber reinforced thermoplastic prepreg tape substrate to be treated is activated to improve the surface activity, and the surface energy is improved to ensure that the subsequent composite resin powder is uniformly attached.

[0040] Step S2, the activated fiber reinforced thermoplastic prepreg tape substrate is heated to make the temperature T1 of the surface to be treated meet: Tm-80℃ ≤ T1<Tm; wherein Tm is the melting point of the matrix resin in the fiber reinforced thermoplastic prepreg tape substrate. In this way, the fiber reinforced thermoplastic prepreg tape substrate to be treated is softened but does not have obvious flowability.

[0041] Step S3, the composite resin powder is uniformly scattered on the surface of the heated fiber reinforced thermoplastic prepreg tape substrate to be treated to form an initial powder layer with a thickness of 8~30µm; wherein the composite resin powder contains 90~99.5wt% of main body resin powder and 0.5~10wt% of functional additive powder, the material of the main body resin powder is the same or compatible with the matrix resin in the fiber reinforced thermoplastic prepreg tape substrate, and the functional additive powder is any one or two or more mixtures of high flowability resin, maleic anhydride grafted interface compatibilizer, and core-shell structure polymer toughening agent. The median particle size D50 of the composite resin powder is 5~30µm.

[0042] Step S4, the fiber reinforced thermoplastic prepreg tape substrate with the initial powder layer is passed through the nip of the heated extrusion roller set, and under the combined action of heat and pressure, the initial powder layer is melted and fused with the resin on the surface of the fiber reinforced thermoplastic prepreg tape substrate to be treated. After leaving the nip, the in-situ formed fiber reinforced thermoplastic prepreg tape product is obtained based on the heat sinking effect; wherein the heating temperature of the heated extrusion roller set is T2, Tm ≤ T2 ≤ Tm+60℃, and T2≥T1+10℃.

[0043] The present application passes the fiber reinforced thermoplastic prepreg tape substrate with the initial powder layer through the nip of the heated extrusion roller set with heating function. The top roller of the heated extrusion roller set (the upper roller is called the top roller, and the lower roller is called the bottom roller) is set to a heating temperature T2, which is not lower than the melting point Tm of the matrix resin in the fiber reinforced thermoplastic prepreg tape substrate. During the extrusion process, since the body temperature of the prepreg tape is low (from the heating temperature T1 of step S3, and T1<T2), when it contacts the high-temperature heated top roller, a transient temperature gradient field is formed from the contact surface to the interior of the prepreg tape body. Under the combined action of heat and pressure, the powder layer rapidly melts, flows, and fully diffuses and fuses with the activated surface resin of the prepreg tape. After leaving the nip, due to the separation from the high-temperature roller and the cooling effect of the prepreg tape body as a heat sink, the melted composite resin powder material is quickly cooled and shaped, thereby forming a functional surface layer without pores, delamination, and continuous interface.

[0044] The process of the heat sink cooling of the present application is as follows: the fiber reinforced thermoplastic prepreg tape substrate with the initial powder layer is only heated to a surface temperature T1 (lower than the melting point Tm) before entering the extrusion nip. Therefore, the internal (core) temperature is lower, and the whole is like a huge solid with a lower temperature. The fiber reinforced thermoplastic prepreg tape substrate with the initial powder layer is in contact with the high-temperature heating top roller (T2≥ Tm), and the powder and the extremely thin surface layer resin at the contact surface are instantaneously melted. However, since the contact time is very short, and the prepreg body is a "cold" entity, the heat does not have enough time to transfer to the deep inside of the prepreg. This forms an extremely steep temperature gradient: from the contact surface to the inside of the prepreg, the temperature drops sharply. When the prepreg leaves the nip, its surface no longer receives heat input from the heating top roller. At this time, the prepreg body with a lower temperature and a huge heat capacity plays the role of a "heat sink", and begins to frantically and rapidly absorb heat from the just-melted, high-temperature thin functional surface layer. This sharp heat dissipation makes the functional layer material cross the solidification point in a very short time and re-solidify.

[0045] The benefits of the heat sink cooling based on the heat sink effect of the present application include: Prevent excessive infiltration: if the cooling is slow, the melted functional surface layer resin will excessively penetrate into the fiber bundle of the prepreg body due to capillary action, etc. This will consume the valuable resin for filling interlayer pores, and may even cause the surface layer fibers to be exposed. Rapid cooling "locks" the functional surface layer on the surface, ensuring its role as an independent resin-rich layer.

[0046] Form a gradient interface: under the rapid cooling of the heat sink effect, the mutual diffusion and molecular chain entanglement of the functional surface layer resin and the prepreg surface layer resin are "instantaneously frozen". This non-equilibrium rapid cooling helps to form a diffusion transition layer with continuous changes in composition and performance, rather than a clear and sharp interface, thereby obtaining a stronger interface bonding.

[0047] Maintain controllable structure: rapid solidification enables the thickness and morphology of the functional surface layer to be accurately maintained, avoiding uneven distribution or "resin tumors" of the functional surface layer due to resin flow and gravity.

[0048] The activation treatment of the fiber reinforced thermoplastic prepreg tape substrate to be treated surface in step S1 of the present application is realized by using a corona treatment instrument or an atmospheric plasma torch. When the corona treatment instrument is used for activation treatment, the power of the corona treatment instrument is 200-1000 W, and the treatment speed is 1-10 m / min.

[0049] The high flowability resin adopted by the present application is a resin with a melt viscosity lower than that of the base resin of the prepreg tape, including a resin with the same type as the base resin but a lower molecular weight, and a resin with a different type from the base resin and a lower inherent viscosity. In specific implementation, the high flowability resin of the present application adopts at least one of polyetherimide, polyethersulfone or a low molecular weight polyether ether ketone. The maleic anhydride grafted interface compatibilizer of the present application adopts at least one of maleic anhydride grafted polyetherimide (PEI-g-MAH) and maleic anhydride grafted styrene-ethylene-butylene-styrene copolymer (SEBS-g-MAH); the core-shell structure polymer toughening agent adopts at least one of methyl methacrylate-butadiene-styrene copolymer (MBS), acrylate core-shell copolymer (ACR) and silicone-resin composite core-shell polymer (a core-shell structure polymer toughening agent with polysiloxane as the core and a thermoplastic resin as the shell).

[0050] As shown in Figure 2 The in-situ forming method of the present application is realized based on a fiber-reinforced thermoplastic prepreg tape in-situ forming system, wherein the fiber-reinforced thermoplastic prepreg tape in-situ forming system comprises, in sequence along the conveying direction of the fiber-reinforced thermoplastic prepreg tape substrate, a unwinding device 1, a prepreg tape surface activation processor 2, a heater 3, a powder sprayer 4, a heated extrusion roller group 5, a traction roller group 6 and a winding device 7. The fiber-reinforced thermoplastic prepreg tape in-situ forming system of the present application realizes the process of the fiber-reinforced thermoplastic prepreg tape in-situ forming method as follows: the fiber-reinforced thermoplastic prepreg tape substrate is unwound from the unwinding device 1, and then the surface to be treated of the fiber-reinforced thermoplastic prepreg tape substrate is activated by the prepreg tape surface activation processor 2, the activated fiber-reinforced thermoplastic prepreg tape substrate is heated by the heater 3, the composite resin powder is uniformly sprayed on the surface to be treated of the heated fiber-reinforced thermoplastic prepreg tape substrate by the powder sprayer 4, the heated extrusion roller group 5 performs hot pressing and fusion, and then the in-situ formed fiber-reinforced thermoplastic prepreg tape product is obtained by heat sinking and cooling, and then conveyed to the winding device 7 by the traction roller group 6 for winding. In specific implementation, the fiber-reinforced thermoplastic prepreg tape in-situ forming system is added to the conventional prepreg tape production line.

[0051] In specific implementation, the heater 3 is realized by an infrared heater, a hot air oven or a contact heating plate, and the powder sprayer 4 is realized by a vibrating screen powder sprayer, an electrostatic powder sprayer or a doctor blade powder sprayer. Between the heater 3 and the powder sprayer 4, and / or between the powder sprayer 4 and the heated extrusion roller group 5, a guide roller or a support plate for supporting and guiding the prepreg tape is arranged.

[0052] The heating type extrusion roller group 5 of the present application comprises a heating top roller for heating the surface of the fiber reinforced thermoplastic prepreg tape substrate on which the initial powder layer is sprayed, and a supporting bottom roller arranged below the heating top roller, wherein the supporting bottom roller is a normal temperature roller or a cooling roller, the area between the heating top roller and the supporting bottom roller is a nip, the nip height is less than the total thickness of the fiber reinforced thermoplastic prepreg tape substrate and the powder layer passing therethrough, and the compression ratio is 5%-30%; the linear pressure of the heating type extrusion roller group 5 is 10-25 kg / cm. The heating top roller of the heating type extrusion roller group 5 of the present application is internally integrated with an electric heating element and a temperature sensor, and is connected with an external temperature control system to realize accurate closed-loop control of the roller surface temperature.

[0053] The fiber reinforced thermoplastic prepreg tape prepared by the above-mentioned in-situ forming method of fiber reinforced thermoplastic prepreg tape has a functional surface layer on at least one surface of the prepreg tape, the functional surface layer is formed by melting of the composite resin powder, and the functional surface layer and the prepreg tape body form a continuous interface structure without delamination through a diffusion transition layer; wherein the diffusion transition layer is an interfacial compatible zone formed by mutual diffusion and molecular chain entanglement of the functional surface layer and the matrix resin of the prepreg tape body under the action of heat pressing. In specific implementation, after the thickness of the initial powder layer is reduced by the subsequent heat pressing fusion step, a thinner and denser functional surface layer is formed due to the compaction, melting and partial mutual diffusion of the powder with the matrix resin, and the thickness of the functional surface layer is preferably 5-20 μm.

[0054] The fiber reinforced thermoplastic prepreg tape of the present application has at least one functional surface layer (i.e. the outermost layer of the gradient interface structure) on one side. This layer is a continuous area rich in resin and basically free of reinforcing fibers, and forms a continuous interface without delamination with the prepreg tape body through a diffusion transition layer. The resin-rich layer provides excellent interface fusion and gap filling capacity for subsequent composite layer forming.

[0055] A composite product prepared by using the above-mentioned fiber reinforced thermoplastic prepreg tape through a winding or automatic laying process.

[0056] Example 1: Preparation of CF / PEEK prepreg tape with functional surface layer CF / PEEK prepreg tape (carbon fiber reinforced polyether ether ketone prepreg tape) prepared by suspension impregnation method was used as the substrate. Before winding, the Figure 2The prepreg tape was first surface-activated by a corona treatment instrument (power 500 W, processing speed 5 m / min), and then heated to 340 °C (Tm of PEEK = 343 °C) by a heater. The prepared composite resin powder (consisting of 98 wt% PEEK powder and 2 wt% polyetherimide (PEI) powder, which was designed to take advantage of the good compatibility of PEI with PEEK and its relatively low melt viscosity to optimize the flowability and interfacial fusion effect of the functional layer) was uniformly sprinkled on the surface of the prepreg tape to be treated by a powder sprayer. The median particle size D50 of the resin powder was 10 pm, and the average thickness of the powder layer was 22 pm. Subsequently, the prepreg tape was subjected to hot-press fusion by a heated extrusion roller set (the temperature of the top roller of the extrusion roller set was set to 380 °C, and the linear pressure was 20 kg / cm). The sample was prepared by ±45° superimposed layering. Microscopic measurement showed that the constructed functional surface layer was dense and continuous, with a thickness of about 12 pm.

[0057] Comparative Example 1: Preparation of CF / PEEK prepreg tape The same substrate CF / PEEK prepreg tape as in Example 1 was used, but without surface activation, powdering and hot-press fusion treatment, and was directly wound. The sample was prepared by ±45° superimposed layering.

[0058] Example 2: Preparation of CF / PEKK prepreg tape with functional surface layer CF / PEKK prepreg tape (carbon fiber reinforced polyether ketone ketone prepreg tape) was used as the substrate. The process was the same as in Example 1, with the following parameters adjusted: corona power 700 W, processing speed 8 m / min, surface heating to 290 °C (Tm of PEKK = 305 °C), composite powder 98 wt% PEKK and 2 wt% PEI, powder median particle size D50 8 pm, powder layer average thickness 22 pm, extrusion top roller temperature 360 °C, linear pressure 25 kg / cm. The thickness of the functional surface layer was about 12 pm.

[0059] Comparative Example 2: Preparation of CF / PEKK prepreg tape The same substrate CF / PEKK prepreg tape as in Example 2 was used, but without subsequent treatment, and the sample was prepared by ±45° superimposed layering.

[0060] Example 3: Preparation of CF / PPS prepreg tape with functional surface layer Example 2: CF / PPS prepreg with functionalized surface layer

[0061] Comparative Example 3: CF / PPS prepreg preparation The same CF / PPS prepreg as in Example 2 was used as the substrate, but no subsequent treatment was performed. The sample was prepared by stacking ±45° plies.

[0062] Example 4: CF / LMPAEK prepreg with functionalized surface layer preparation CF / LMPAEK prepreg was used as the substrate. The process was the same as in Example 1, with the following parameters: corona power 400 W, treatment speed 5 m / min, surface heating to 290°C (Tm of LMPAEK = 305°C), composite powder 98 wt% LMPAEK and 2 wt% silicone rubber-PEI core-shell particles (which are organic silicone-resin composite core-shell polymers, specifically core-shell particles with polysiloxane (silicone rubber) as the core and polyetherimide (PEI) as the shell), powder D50 5 µm, average powder layer thickness 18 µm, extrusion top roller temperature 360°C, linear pressure 25 kg / cm. The functionalized surface layer was about 10 µm thick.

[0063] Comparative Example 4: CF / LMPAEK prepreg preparation The same CF / LMPAEK prepreg as in Example 4 was used as the substrate, but no subsequent treatment was performed. The sample was prepared by stacking ±45° plies.

[0064] The in-plane shear strength and modulus of the prepreg of the above examples and comparative examples were tested using ASTM D3518 - Standard Test Methods for In-Plane Shear Response of Polymer Matrix Composite Materials, the interlaminar shear strength (ILSS) of the prepreg of the above examples and comparative examples was tested using ASTM D2344 - Standard Test Methods for Short-Beam Strength and Flexural Fatigue of Polymer Matrix Composite Materials, and the porosity of the prepreg of the above examples and comparative examples was tested using ASTM D2734 - Standard Test Methods for Void Content of Reinforced Thermoplastics. The test results are shown in Table 1 below: Table 1 is a comparison table of the performance tests of Examples 1-4 and Comparative Examples 1-4

[0065] From Table 1, the test data show that the in-plane shear strength, in-plane shear modulus and interlaminar shear strength of each embodiment are obviously improved compared with the corresponding untreated prepreg, and the porosity is obviously reduced. Among them, the interlaminar shear strength of each embodiment is increased by more than 10% compared with the corresponding untreated prepreg, which fully proves the effectiveness and progressiveness of the present application.

[0066] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method of forming a fiber reinforced thermoplastic prepreg tape in situ, characterized by, The method comprises the following steps: Step S1, activating the surface of the fiber-reinforced thermoplastic prepreg tape substrate to be treated to improve the surface activity; Step S2, heating the fiber-reinforced thermoplastic prepreg tape substrate to be treated to make the temperature T1 of the surface to be treated meet the condition: Tm-80℃ ≤ T1 < Tm; wherein Tm is the melting point of the matrix resin in the fiber-reinforced thermoplastic prepreg tape substrate; Step S3, uniformly sprinkle the composite resin powder on the surface of the heated fiber-reinforced thermoplastic prepreg tape substrate to be treated to form an initial powder layer with a thickness of 8-30µm; wherein the composite resin powder comprises 90-99.5wt% of main resin powder and 0.5-10wt% of functional additive powder, the material of the main resin powder is the same as or compatible with the matrix resin in the fiber-reinforced thermoplastic prepreg tape substrate, and the functional additive powder is any one or a mixture of two or more of high-flow resin, maleic anhydride grafted interfacial compatibilizer, and core-shell structure polymer toughening agent; Step S4, passing the fiber-reinforced thermoplastic prepreg tape substrate with the initial powder layer through the nip of a heating type extrusion roller set to make the initial powder layer melt and fuse with the resin on the surface of the fiber-reinforced thermoplastic prepreg tape substrate to be treated under the combined action of heat and pressure, and obtaining an in-situ formed fiber-reinforced thermoplastic prepreg tape product through heat sink cooling based on the heat sink effect after leaving the nip; wherein the heating temperature of the heating type extrusion roller set is T2, and Tm ≤ T2 ≤ Tm+60℃.

2. A method of in-situ forming of fibre reinforced thermoplastic prepreg tape according to claim 1, characterised in that, The surface of the fiber-reinforced thermoplastic prepreg tape substrate to be treated in step S1 is activated by a corona treatment instrument or an atmospheric plasma torch; when the corona treatment instrument is used for activation, the power of the corona treatment instrument is 200-1000W, and the treatment speed is 1-10m / min.

3. A method of in-situ forming of fiber reinforced thermoplastic prepreg tape according to claim 1, wherein, The high-flow resin is at least one of polyetherimide, polyethersulfone, or low-molecular-weight polyether ether ketone; The maleic anhydride grafted interfacial compatibilizer is at least one of maleic anhydride grafted polyetherimide or maleic anhydride grafted styrene-ethylene-butylene-styrene copolymer; The core-shell structure polymer toughening agent is at least one of methyl methacrylate-butadiene-styrene copolymer, acrylate core-shell copolymer, or silicone-resin composite core-shell polymer.

4. A method of in-situ forming of fiber reinforced thermoplastic prepreg tape according to claim 1, wherein, The median particle size D50 of the composite resin powder is 5-30µm.

5. A method of in-situ forming of fiber reinforced thermoplastic prepreg tape according to claim 1, wherein, The heating temperature T2 of the heating type extrusion roller set in step S4 is T1+10℃.

6. A method according to any one of claims 1 to 5, wherein the method is a fibre- reinforced thermoplastic prepreg tape in-situ forming method, characterised in that, The steps S1-S4 are realized based on a fiber-reinforced thermoplastic prepreg tape in-situ forming system, which comprises, in sequence along the conveying direction of the fiber-reinforced thermoplastic prepreg tape substrate, an unwinding device (1), a prepreg tape surface activation processor (2), a heater (3), a powder sprayer (4), a heating type extrusion roller set (5), a traction roller set (6), and a winding device (7); the fiber-reinforced thermoplastic prepreg tape in-situ forming system realizes the process of the fiber-reinforced thermoplastic prepreg tape in-situ forming method as follows: The fiber-reinforced thermoplastic prepreg tape substrate is discharged by a unwinding device (1), and is sequentially subjected to activation treatment on the surface of the fiber-reinforced thermoplastic prepreg tape substrate to be treated by a prepreg tape surface activation treatment device (2), heating of the fiber-reinforced thermoplastic prepreg tape substrate subjected to the activation treatment by a heater (3), uniform sprinkling of composite resin powder on the surface of the heated fiber-reinforced thermoplastic prepreg tape substrate to be treated by a powder sprayer (4), hot-pressing fusion by a heating type extrusion roller set (5), and then in-situ forming of a fiber-reinforced thermoplastic prepreg tape product by heat sinking cooling, and then the product is conveyed by a traction roller set (6) to a winding device (7) for winding.

7. A method according to claim 6, wherein the fibre reinforced thermoplastic prepreg tape is formed in situ by the process of: The heating type extrusion roller set (5) comprises a heating top roller for heating the surface of the fiber-reinforced thermoplastic prepreg tape substrate sprinkled with an initial powder layer to be treated, and a supporting bottom roller arranged below the heating top roller, wherein the area between the heating top roller and the supporting bottom roller is a nip, the height of the nip is less than the total thickness of the fiber-reinforced thermoplastic prepreg tape substrate and the powder layer passing therethrough, and the compression ratio of the nip is 5% to 30%; and the linear pressure of the heating type extrusion roller set (5) is 10 to 25 kg / cm.

8. A fiber reinforced thermoplastic prepreg tape prepared by the in-situ forming method of a fiber reinforced thermoplastic prepreg tape according to any one of claims 1 to 7, characterized in that, The prepreg tape has a functional surface layer on at least one surface thereof, the functional surface layer is formed by melting of the composite resin powder, and the functional surface layer and the prepreg tape body form a continuous interface structure without delamination through a diffusion transition layer; wherein the diffusion transition layer is an interface compatible zone formed by mutual diffusion and molecular chain entanglement of the functional surface layer and the matrix resin of the prepreg tape body under the action of hot pressing.

9. A fiber reinforced thermoplastic prepreg tape according to claim 8, wherein, The thickness of the functional surface layer is 5 to 20 μm.

10. A composite article, characterized by, The fiber-reinforced thermoplastic prepreg tape prepared by the in-situ forming method of the fiber-reinforced thermoplastic prepreg tape according to any one of claims 1 to 7, or the fiber-reinforced thermoplastic prepreg tape according to claim 8 or 9, is subjected to a winding or automatic laying process.

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