Fiber band and preparation method thereof

Abstract

The invention provides a fiber belt and a preparation method thereof. The fiber band comprises a carbon fiber layer, wherein an emulsion setting agent is filled in a gap in the carbon fiber layer; the toughening layer is bonded to the surface of at least one side of the carbon fiber layer through a setting agent; the setting agent comprises an irregular flaky powder setting agent. According to the fiber belt provided by the invention, the fiber belt is shaped from the interior / interlayer of the fiber belt, so that the fiber belt has moderate viscosity, flexibility, dimensional precision, cutting property and strength, can keep a stable shape in the conveying process, and resists excessive sagging caused by self gravity and distortion caused by external disturbance. And when the carbon fiber composite material preform is prepared, the low-viscosity liquid resin can quickly and uniformly permeate into the whole preform from the flow channel in the fiber belt, so that the glue injection and curing time is shortened, and the production efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of composite materials, and in particular to a fiber tape and a preparation method thereof. BACKGROUND

[0002] Carbon fiber composite materials have become the key materials for promoting the performance, safety and economic benefits of civil aviation due to their excellent characteristics such as light weight, high strength, corrosion resistance and fatigue resistance. The automatic placement liquid molding technology for preparing advanced composite materials has become an important direction and inevitable trend of the development of aviation composite materials. The use of automation technology can greatly improve production efficiency and reduce production costs. Among them, the automatic fiber placement technology is controllable, and the number of pre-impregnated yarns can be increased or decreased in real time to meet the actual placement requirements, which is suitable for the automatic molding of large-size components with irregular shapes and complex boundaries. This technology has become a typical manufacturing process technology for large and complex composite parts. At present, the automatic fiber placement process generally uses prepreg tape. Since the thickness of the prepreg tape after curing is relatively large, and the energy consumption of the later autoclave curing is very large, in order to reduce costs and meet the challenges of the efficiency improvement of civil aircraft manufacturing, the international composite industry has researched the OOA (out of autoclave process) process, and dry fibers have emerged and made great progress. How to improve the slitting precision, automatic placement efficiency, resin permeability and stability of the preform of dry fibers has become the current focus of research. SUMMARY

[0003] To solve the problems in the related art, the present disclosure provides a fiber tape and a preparation method thereof.

[0004] According to a first aspect of an embodiment of the present disclosure, a fiber tape is provided, which comprises: a carbon fiber layer, the internal gaps of the carbon fiber layer being filled with an emulsion sizing agent; a toughening layer, the toughening layer being bonded to the surface of at least one side of the carbon fiber layer by a sizing agent; the sizing agent comprising irregular flaky powder sizing agent.

[0005] In some embodiments of the present disclosure, the mass of the emulsion sizing agent is 0.8-3.2% of the mass of the carbon fiber layer; the emulsion sizing agent comprises the following components, and the content of each component is represented as follows in terms of mass fraction: water-soluble epoxy resin 0.4-2.6 parts, composite surfactant 0.1-1.3 parts, deionized water 4.1-6.9 parts; The composite surfactant comprises a non-ionic surfactant and an anionic surfactant, wherein the mass ratio of the non-ionic surfactant to the anionic surfactant is (1.5-4):1. The water-soluble epoxy resin has a molecular weight distribution Mw / Mn of 1.4-2.2 and an epoxy equivalent weight of 150-250 g / eq.

[0006] In some embodiments of the present disclosure, the sizing agent has a mass of 5.6-8.5% of the mass of the carbon fiber layer; the sizing agent comprises the following components, and the content of each component is represented as follows in terms of mass fraction: reactive epoxy resin 25-48 parts, non-reactive epoxy resin 52-75 parts.

[0007] In some embodiments of the present disclosure, the sizing agent is arranged on the surface of at least one side of the carbon fiber layer to form a sizing agent layer.

[0008] In some embodiments of the present disclosure, the toughening layer comprises a self-supporting porous structure; the unit area weight of the toughening layer is 6-20 g / m 2 , and the thickness is ≤70 μm.

[0009] In some embodiments of the present disclosure, the carbon fiber layer comprises a carbon fiber unidirectional tape layer composed of a plurality of carbon fiber single yarns; The volume fraction of the carbon fiber single yarns in the fiber tape is 50%-60%; the unit area weight of the carbon fiber layer is 170-210 g / m 2 ; and the thickness ratio of the carbon fiber layer to the toughening layer is (8.5-36.4):1.

[0010] According to a second aspect of the embodiments of the present disclosure, a preparation method of a fiber tape is provided, and the preparation method is used to prepare the fiber tape as described above; the preparation method comprises the following steps: After the carbon fiber layer is impregnated with the emulsion sizing agent, the impregnated carbon fiber layer is obtained by drying and heating under first preset conditions; The toughening layer is bonded to the surface of at least one side of the impregnated carbon fiber layer through the sizing agent to form the fiber tape.

[0011] In some embodiments of the present disclosure, before the toughening layer is bonded to the surface of at least one side of the impregnated carbon fiber layer through the sizing agent to form the fiber tape, the preparation method further comprises the following steps: The sizing agent is applied to the surface of at least one side of the impregnated carbon fiber layer to form a sizing agent layer; the sizing agent comprises irregular flaky powder sizing agent.

[0012] In some embodiments of the present disclosure, the step of bonding the toughening layer to the surface of at least one side of the impregnated carbon fiber layer through the sizing agent to form the fiber tape comprises the following steps: bonding the toughening layer to the sizing agent layer away from the side of the impregnated carbon fiber layer, and hot-pressing the impregnated carbon fiber layer and the toughening layer under second preset conditions to make the carbon fiber layer and the toughening layer tightly composite, to obtain the fiber tape, and winding the fiber tape.

[0013] In some embodiments of the present disclosure, the first preset conditions include: a first preset temperature of 140-190°C, a preset wind speed of 0.8-2.0 m / s, and a first preset time length of 30-60 s; The second preset conditions include: a first hot-pressing stage, a second preset temperature of 75-110°C, and a first preset pressure of 0.5-0.9 MPa; a second hot-pressing stage, a third preset temperature of 95-130°C, and a second preset pressure of 1.1-1.6 MPa; a third hot-pressing stage, a fourth preset temperature of 115-140°C, and a third preset pressure of 1.7-2.3 MPa.

[0014] The beneficial effects of the present disclosure include but are not limited to: the fiber tape provided by the present disclosure is internally / interlayer shaped, so that the fiber tape has moderate adhesion, flexibility, dimensional accuracy, cutting property, strength, and can maintain a stable shape during transportation, resist excessive sagging caused by its own gravity and distortion caused by external disturbance. And when preparing a carbon fiber composite material preform, the low-viscosity liquid resin can quickly and uniformly penetrate the entire preform from the flow channel in the fiber tape, shorten the injection and curing time, and improve the production efficiency.

[0015] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which are incorporated into and form part of the description, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of embodiments of the present disclosure. In these drawings, like reference numerals are used to represent similar elements. The drawings described below are some embodiments of the present disclosure, not all embodiments. For those skilled in the art, other drawings can be obtained from these drawings without creative labor.

[0017] Figure 1 Flowchart of the preparation method of the fiber tape of an exemplary embodiment of the present disclosure; Figure 2 Schematic diagram of the cross-sectional structure of the fiber tape of an exemplary embodiment of the present disclosure; Figure 3A schematic view of a reverse side of a fiber tape of an example embodiment of the present disclosure; Figure 4 A schematic view of a front side of a fiber tape of an example embodiment of the present disclosure. DETAILED DESCRIPTION

[0018] In order to make the objects, technical solutions and advantages of the present disclosure clearer, the technical solutions of the present disclosure will be described clearly and completely below in conjunction with embodiments of the present disclosure. Obviously, the described embodiments are only some of the embodiments of the present disclosure, but not all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present disclosure. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other in any manner without conflict.

[0019] The automatic fiber placement process of carbon fiber composites generally uses prepreg tapes. Since the thickness of the prepreg tape after curing is relatively large, and the energy consumption of the post-curing in the autoclave is very large, in order to reduce the cost and cope with the challenge of the efficiency improvement of civil aircraft manufacturing, dry fiber emerges as the times require. The dry fiber prepared in the related art has the following problems: sagging, floating, twisting or stacking during the process of being conveyed from the material roll to the fiber placement head; excessive deformation, broadening or even crushing under the pressure of the fiber placement head roller during the placement process, resulting in uneven thickness and reduced permeability; after the placement is completed, the self-supporting ability is poor, and the material is prone to sagging, deforming and interlaminar slipping due to gravity or slight disturbance after the pressure is removed, so that it is difficult to maintain the precise shape and fiber orientation, which affects the subsequent mold assembly and resin injection; the material is too soft, and wrinkles are more likely to occur when the placement path is turned or the placement pressure is applied.

[0020] Based on this, the present disclosure provides a fiber tape, which is internally / interlaminarly shaped so that the fiber tape has moderate adhesion, flexibility, dimensional accuracy, cuttability and strength, and can maintain a stable shape during the conveying process, and resist excessive sagging caused by its own gravity and twisting caused by external disturbance. And when preparing a carbon fiber composite preform, the low-viscosity liquid resin can quickly and uniformly penetrate the entire preform from the flow channel in the fiber tape, shorten the injection and curing time, and improve the production efficiency.

[0021] An example embodiment of the present disclosure provides a fiber tape, which comprises: a carbon fiber layer and a toughening layer, the internal gap of the carbon fiber layer is filled with an emulsion sizing agent, and the toughening layer is bonded to the surface of at least one side of the carbon fiber layer by the sizing agent; the sizing agent comprises irregular flaky powder sizing agent.

[0022] The gap in the carbon fiber layer in the fiber tape provided by the embodiment is filled with the emulsion sizing agent, which can enhance the adhesion between the tows in the carbon fiber layer, and is conducive to improving the width stability of the fiber tape, so that the fiber tape can maintain a stable shape in the automatic fiber placement and conveying process when the fiber tape is applied to the preparation of the carbon fiber composite preform, and the stability of the carbon fiber composite preform is improved. The toughening layer is bonded to the surface of at least one side of the carbon fiber layer by the sizing agent, which can play a role in sizing and toughening the fiber tape. The sizing agent includes irregular flaky powder sizing agent, which can play a role in sizing the carbon fiber layer on the surface of at least one side of the carbon fiber layer, and on the other hand, the irregular flaky powder sizing agent does not completely cover the carbon fiber layer, leaving a flow channel for the resin in the thickness direction of the preform during the preparation of the carbon fiber composite preform, so that the low-viscosity liquid resin can quickly and uniformly penetrate the entire preform. Therefore, the fiber tape provided by the embodiment is internally / sintered between layers, so that the fiber tape has moderate adhesion, flexibility, dimensional accuracy, cutting property, strength, can maintain a stable shape during conveying, and resist excessive sagging caused by its own gravity and distortion caused by external disturbance. And when preparing the carbon fiber composite preform, the low-viscosity liquid resin can quickly and uniformly penetrate the entire preform from the flow channel in the fiber tape, shorten the injection and curing time, and improve the production efficiency.

[0023] In an exemplary embodiment, the mass of the emulsion sizing agent is 0.8-3.2% of the mass of the carbon fiber layer; the emulsion sizing agent comprises the following components, and the content of each component is represented as follows in mass fraction: Water-soluble epoxy resin 0.4-2.6 parts; Composite surfactant 0.1-1.3 parts; Deionized water 4.1-6.9 parts.

[0024] The emulsion sizing agent can be softened by heat to bond and shape the carbon fiber tows inside the carbon fiber layer, to improve the stability and stiffness of the fiber tape after slitting, to keep the shape (width, cross section) stable during conveying, to resist excessive sagging caused by its own gravity and distortion caused by external disturbance, and to ensure accurate and stable feeding into the fiber placement head, while improving the path planning accuracy of the fiber placement head. In this embodiment, the mass of the emulsion sizing agent is 0.8-3.2% of the mass of the carbon fiber layer. At this mass ratio, the emulsion sizing agent can fully fill the gaps in the carbon fiber layer, and excessive use of the emulsion sizing agent can avoid excessive weight or stiffness of the fiber tape, while maintaining the lightweight and flexibility of the fiber tape. For example, the mass of the emulsion sizing agent can be 0.8%, 1.5%, 2.0% or 3.2% of the mass of the carbon fiber layer, and the mass of the emulsion sizing agent can also be any value between the example percentages, for example, the mass of the emulsion sizing agent can be any value between 1.0-2.5% of the mass of the carbon fiber layer.

[0025] The water-soluble epoxy resin, as the main film-forming material in the emulsion sizing agent, can provide good adhesion and chemical stability. The mass fraction of the water-soluble epoxy resin is controlled at 0.4-2.6 parts, which can ensure the effective adhesion of the water-soluble epoxy resin to the carbon fiber, and avoid excessive use of the water-soluble epoxy resin, which can cause excessive weight or stiffness of the fiber tape. For example, the mass fraction of the water-soluble epoxy resin can be 0.4 parts, 1.0 parts, 1.8 parts or 2.6 parts, and the mass fraction of the water-soluble epoxy resin can also be any value between the example mass fractions, for example, the mass fraction of the water-soluble epoxy resin can be any value between 0.6-2.2 parts.

[0026] The composite surfactant can improve the wettability and dispersibility of the emulsion sizing agent on the surface of the carbon fiber, and ensure uniform distribution of the emulsion sizing agent in the gaps of the carbon fiber layer. The mass fraction of the composite surfactant is controlled at 0.1-1.3 parts, which can ensure the wettability and dispersibility of the emulsion sizing agent on the surface of the carbon fiber, and avoid excessive use of the composite surfactant affecting the adhesion of the water-soluble epoxy resin to the carbon fiber. For example, the mass fraction of the composite surfactant can be 0.1 parts, 0.5 parts, 0.8 parts or 1.3 parts, and the mass fraction of the composite surfactant can also be any value between the example mass fractions, for example, the mass fraction of the composite surfactant can be any value between 0.3-1.0 parts.

[0027] The deionized water, as a solvent of the emulsion sizing agent, can adjust the concentration of the emulsion sizing agent. For example, the mass fraction of the deionized water can be controlled to be 4.1-6.9 parts according to actual needs to adjust the concentration of the emulsion sizing agent, for example, the mass fraction of the deionized water can be 4.1, 5.0 or 6.9, and the mass fraction of the deionized water can also be any value between the exemplary mass fractions, for example, the mass fraction of the deionized water can be any value between 4.5 and 6.2.

[0028] In an exemplary embodiment, the composite surfactant comprises a non-ionic surfactant and an anionic surfactant, and the mass ratio of the non-ionic surfactant to the anionic surfactant is (1.5-4):1.

[0029] In this embodiment, the composite surfactant comprises a non-ionic surfactant and an anionic surfactant, the non-ionic surfactant provides good emulsification and compatibility for the emulsion sizing agent, and the non-ionic surfactant can be, for example, a fatty alcohol polyoxyethylene ether, an alkyl phenol polyoxyethylene ether, a sorbitan ester, an alkyl amine oxide, etc. The anionic surfactant enhances the electrostatic stability and permeability of the emulsion sizing agent, and the anionic surfactant can be, for example, a fatty alcohol sulfate, sodium alkyl benzene sulfonate, an alkyl sulfonate. Controlling the mass ratio of the non-ionic surfactant to the anionic surfactant to be (1.5-4):1 can optimize the stability and wetting effect of the emulsion sizing agent, prevent the emulsion sizing agent from being layered or aggregated, and improve the bonding and sizing efficiency of the carbon fibers. For example, the mass ratio of the non-ionic surfactant to the anionic surfactant can be 1.5:1, 3:1 or 4:1, and the mass ratio of the non-ionic surfactant to the anionic surfactant can also be any value between the exemplary mass ratios, for example, the mass ratio of the non-ionic surfactant to the anionic surfactant can be any value between (2.0-3.5):1.

[0030] In an exemplary embodiment, the water-soluble epoxy resin has a molecular weight distribution Mw / Mn of 1.4-2.2 and an epoxy equivalent weight of 150-250 g / eq.

[0031] In this embodiment, the water-soluble epoxy resin has a molecular weight distribution Mw / Mn of 1.4-2.2, and the relatively narrow molecular weight distribution ensures the uniformity and consistency of the water-soluble epoxy resin, so as to ensure that the reaction is more controllable during the bonding and curing process. For example, the water-soluble epoxy resin can have a molecular weight distribution Mw / Mn of 1.4, 2.0 or 2.2, and the water-soluble epoxy resin can also have any value between the exemplary values, for example, the water-soluble epoxy resin can have a molecular weight distribution Mw / Mn of any value between 1.6 and 2.0.

[0032] The water-soluble epoxy resin has an epoxy equivalent weight of 150-250 g / eq, which ensures that the water-soluble epoxy resin has moderate reactivity and adhesive strength, thereby forming an effective adhesive sizing on the carbon fibers. For example, the water-soluble epoxy resin can have an epoxy equivalent weight of 150 g / eq, 200 g / eq, or 250 g / eq, and the water-soluble epoxy resin can also have an epoxy equivalent weight of any value between the exemplary epoxy equivalent weights, for example, the water-soluble epoxy resin can have an epoxy equivalent weight of any value between 180-220 g / eq.

[0033] In an exemplary embodiment, the water-soluble epoxy resin in the sizing agent is in the form of a powder, and the water-soluble epoxy resin powder has an average particle size (D50) of less than 80-150 nm and a maximum particle size of no more than 300 nm. The carbon fiber filaments in the carbon fiber layer generally have a diameter of 5-8 microns, and the water-soluble epoxy resin powder (D50) < 150 nm can ensure that it can penetrate into the gaps (generally < 1 micron) in the carbon fiber layer to form an effective adhesive sizing on the carbon fiber layer.

[0034] In an exemplary embodiment, the sizing agent has a mass of 5.6-8.5% of the mass of the carbon fiber layer, and the sizing agent includes the following components, and the content of each component is expressed in parts by mass as follows: reactive epoxy resin 25-48 parts, non-reactive epoxy resin 52-75 parts.

[0035] In this embodiment, the sizing agent has a mass of 5.6-8.5% of the mass of the carbon fiber layer, and at this mass ratio, it can be ensured that the sizing agent is sufficient to form a firm adhesive layer to bond the toughening layer to at least one surface of the carbon fiber layer, while avoiding excessive use of the sizing agent resulting in increased costs or excessively high rigidity of the fiber tape. For example, the sizing agent can have a mass of 5.6%, 6.6%, 7.8%, or 8.5% of the mass of the carbon fiber layer, and the mass of the sizing agent can also be any value between the exemplary percentages, for example, the mass of the sizing agent can be any value between 6.2-8.0% of the mass of the carbon fiber layer.

[0036] The sizing agent includes a reactive epoxy resin and a non-reactive epoxy resin. The reactive epoxy resin can be, for example, at least two of a bisphenol F type resin and an alicyclic epoxy resin. The non-reactive epoxy resin can be, for example, at least one of a hydrogenated bisphenol A epoxy resin or a phenol aldehyde epoxy modifier having a softening point of 70-90°C. The reactive epoxy resin undergoes a cross-linking reaction during the hot pressing process to form a three-dimensional network structure, providing the sizing agent with bonding strength and heat resistance. The mass fraction of the reactive epoxy resin is controlled to be 25-48 parts, which can ensure the cross-linking density of the sizing agent and avoid excessive use of the reactive epoxy resin, which can cause brittleness of the sizing agent and deteriorate the impact resistance of the fiber tape. For example, the mass fraction of the reactive epoxy resin can be 25 parts, 30 parts, 40 parts, or 48 parts. The mass fraction of the reactive epoxy resin can also be any value between the exemplary mass fractions, for example, the mass fraction of the reactive epoxy resin can be any value between 30-40 parts.

[0037] The non-reactive epoxy resin, as a toughening component, can improve the flexibility and impact resistance of the sizing agent. The mass fraction of the non-reactive epoxy resin is controlled to be 52-75 parts, which can effectively enhance the flexibility of the sizing agent while avoiding excessive use of the non-reactive epoxy resin and insufficient use of the reactive epoxy resin, which can result in insufficient cross-linking density of the sizing agent. For example, the mass fraction of the non-reactive epoxy resin can be 52 parts, 60 parts, 65 parts, or 75 parts. The mass fraction of the non-reactive epoxy resin can also be any value between the exemplary mass fractions, for example, the mass fraction of the non-reactive epoxy resin can be any value between 55-70 parts.

[0038] In an exemplary embodiment, the sizing agent is disposed on the surface of at least one side of the carbon fiber layer to form a sizing agent layer.

[0039] The sizing agent is disposed on the surface of at least one side of the carbon fiber layer to form a sizing agent layer. On the one hand, the sizing agent layer itself can size and toughen the carbon fiber layer. On the other hand, the sizing agent layer can bond the toughening layer on the surface of at least one side of the carbon fiber layer, further sizing and toughening the carbon fiber layer.

[0040] In an exemplary embodiment, the sizing agent comprises irregular flaky powder sizing agent. The irregular flaky powder sizing agent has an average particle size (D50) of less than 60-80 microns, and a maximum particle size of no more than 150 microns. The carbon fiber monofilament diameter is generally 5-8 microns, and when the irregular flaky powder sizing agent is distributed in an irregular flaky shape on one surface of the carbon fiber layer after being heated and softened, it plays a role in sizing and toughening the carbon fiber layer while being used to bond the toughening layer. When the irregular flaky powder sizing agent is distributed in an irregular flaky shape on both surfaces of the carbon fiber layer after being heated and softened, the sizing agent on one surface is used to bond the toughening layer, and the sizing agent on the other side has moderate and stable viscosity, which can be used for interlayer bonding during automatic laying of the fiber tape, ensuring that the laid layer can be temporarily adhered to the lower layer or the mold, resisting gravity, laying pressure and shear force, and preventing displacement, wrinkling or separation. At the same time, the irregular flaky powder sizing agent does not completely cover the carbon fiber layer, leaving a flow channel for the resin in the thickness direction of the carbon fiber composite preform during the preparation of the carbon fiber composite preform, so that the low-viscosity liquid resin can quickly and uniformly penetrate the entire preform. The fiber tape with moderate surface viscosity after heating is also beneficial to improve the stability of the preform.

[0041] In an exemplary embodiment, the toughening layer comprises a self-supporting porous structure; the unit area weight of the toughening layer is 6-20 g / m 2 , and the thickness is ≤70 μm.

[0042] The toughening layer can be a thermoplastic mesh made of cross-shaped section thermoplastic resin (polyethylene terephthalate, polyether sulfone, polyamide, polyether ether ketone, polyphenylene sulfide, etc.) fibers, which can be prepared by wet spinning and shaped fiber sizing process. The toughening layer is bonded to one side of the carbon fiber layer under the action of the sizing agent. The self-supporting porous structure of the toughening layer has open pores or network, which can retain a flow channel for the resin in the thickness direction of the carbon fiber composite preform during the preparation of the carbon fiber composite preform, so that the low-viscosity liquid resin can quickly and uniformly penetrate the entire preform, playing a role in flow guiding and exhaust.

[0043] The unit area weight of the toughening layer is 6-20 g / m 2 , and the thickness is ≤70 μm, which can ensure the lightweight and ultrathin characteristics of the toughening layer, avoid the existence of the toughening layer significantly increasing the overall weight or thickness of the fiber tape, and maintain the high specific strength and high specific modulus characteristics of the carbon fiber tape. At the same time, the ultrathin design of the toughening layer can avoid the existence of the toughening layer excessively affecting the flexibility and processability of the fiber tape, making it suitable for forming complex-shaped carbon fiber composite preforms. The unit area weight of the toughening layer may, for example, be 6 g / m 2 , 15 g / m 2 or 20 g / m 2The unit area weight of the toughening layer can also be any value between the exemplary unit area weights, for example, the unit area weight of the toughening layer can be 10~15 g / m². 2 The thickness of the toughening layer can be any value between 30 μm, 50 μm, or 70 μm, and can also be any value between the exemplary thicknesses, for example, any value between 35 and 60 μm.

[0044] In one exemplary embodiment, the carbon fiber layer comprises a unidirectional carbon fiber tape layer composed of multiple carbon fiber monofilaments; the carbon fiber monofilaments account for 50% to 60% of the volume fraction of the fiber tape; and the unit area weight of the carbon fiber layer is 170 to 210 g / m². 2 The thickness ratio of the carbon fiber layer to the toughening layer is (8.5~36.4):1.

[0045] In this embodiment, the carbon fiber layer comprises a unidirectional carbon fiber tape layer composed of multiple carbon fiber monofilaments. This structure provides excellent unidirectional strength and stiffness to the fiber tape, making it suitable for applications requiring high load-bearing capacity, such as aerospace or automotive structures. Controlling the volume fraction of carbon fiber monofilaments to 50%–60% ensures the axial strength and stiffness of the fiber tape while avoiding insufficient resin wetting channels due to excessively high carbon fiber monofilament volume fraction, which could lead to product quality defects. For example, the volume fraction of carbon fiber monofilaments can be 50%, 55%, or 60%, or any value between these exemplary volume fractions, such as any value between 53% and 58%. The unit area weight of the carbon fiber layer is controlled to be 170–210 g / m². 2 This approach ensures sufficient mechanical properties for the carbon fiber layer while avoiding increased costs or application limitations due to excessive weight. For example, the area weight of the carbon fiber layer can be 170 g / m². 2 190 g / m 2 Or 210 g / m 2 The area weight of the carbon fiber layer can also be any value between the exemplary area weights, for example, the area weight of the carbon fiber layer can be 180~200 g / m². 2 Any value between.

[0046] The thickness ratio of the carbon fiber layer to the toughening layer is controlled to be (8.5-36.4):1. Within the ratio range, the rigidity contribution of the carbon fiber layer in the fiber tape and the shaping and toughness contribution of the toughening layer can be balanced. When the thickness ratio of the carbon fiber layer to the toughening layer is too large, that is, the carbon fiber layer is too thick, the toughening layer is insufficient for shaping the carbon fiber layer, which can cause the carbon fiber filaments on the side away from the toughening layer in the carbon fiber layer to move or deform; when the thickness ratio of the carbon fiber layer to the toughening layer is too small, that is, the toughening layer is too thick and the carbon fiber layer is too thin, the overall strength of the fiber tape will be reduced. For example, the thickness ratio of the carbon fiber layer to the toughening layer can be 8.5:1, 15.0:1, 25.8:1 or 36.4:1. The thickness ratio of the carbon fiber layer to the toughening layer can also be any value between the exemplary ratios, for example, the thickness ratio of the carbon fiber layer to the toughening layer can be any value between (10.5-30.0):1.

[0047] An example embodiment of the present disclosure provides a method for preparing a fiber tape as described above; as Figure 1 As shown, the method for preparing a fiber tape comprises: S100, impregnate the carbon fiber layer with an emulsion sizing agent, dry and heat under first preset conditions to obtain a rubber-impregnated carbon fiber layer.

[0048] In step S100, the carbon fiber layer is impregnated with an emulsion sizing agent, dried and heated to obtain a rubber-impregnated carbon fiber layer. The interstitial space in the rubber-impregnated carbon fiber layer is filled with emulsion sizing agent, which can enhance the inter-bundle adhesion in the carbon fiber layer, thereby improving the width stability of the fiber tape, allowing the fiber tape to maintain a stable shape during the automatic fiber placement and conveying process when the fiber tape is applied to the preparation of carbon fiber composite preforms, and improving the stability of the carbon fiber composite preforms.

[0049] In an example embodiment, the first preset conditions include a first preset temperature of 140-190℃, a preset wind speed of 0.8-2.0 m / s, and a first preset time of 30-60 s.

[0050] After the carbon fiber layer is impregnated with the sizing agent, the carbon fiber layer is dried and heated at a preset wind speed of 0.8-2.0 m / s and a first preset temperature of 140-190°C for 30-60 s. The sizing agent is softened by heat and dispersed in the interstitial space of the carbon fiber layer to form a bond with the carbon fiber. The first preset temperature can be, for example, 140°C, 150°C, or 190°C. The first preset temperature can also be any value between the example temperatures, for example, the first preset temperature can be any value between 150°C and 180°C. The preset wind speed can be, for example, 0.8 m / s, 1.5 m / s, or 2.0 m / s. The preset wind speed can also be any value between the example wind speeds, for example, the preset wind speed can be any value between 1.0 m / s and 1.8 m / s. The first preset time length can be, for example, 30 s, 15 s, or 60 s. The first preset time length can also be any value between the example time lengths, for example, the first preset time length can be any value between 35 s and 55 s.

[0051] In step S200, the toughening layer is bonded to at least one side of the surface of the impregnated carbon fiber layer by the sizing agent to form a fiber tape.

[0052] In step S200, the toughening layer is bonded to at least one side of the surface of the impregnated carbon fiber layer by the sizing agent to form a fiber tape. The toughening layer can play a role in sizing and toughening the fiber tape, avoiding the problem of lack of self-supporting ability after the fiber tape is laid when the fiber tape is applied to the preparation of the carbon fiber composite preform, and sinking, deforming, and interlayer slipping due to gravity or slight disturbance after the pressing force is removed.

[0053] The preparation method of the fiber tape provided in this embodiment can internally / sup interlayer size the fiber tape, has high width stability, can maintain a stable shape during transportation, and resist excessive sagging due to its own gravity and twisting due to external disturbance. In addition, when preparing a carbon fiber composite preform, the low-viscosity liquid resin can quickly and uniformly penetrate the entire preform from the flow channel in the fiber tape, shorten the gel injection and curing time, and improve the production efficiency.

[0054] In an example embodiment, before the toughening layer is bonded to at least one side of the surface of the impregnated carbon fiber layer by the sizing agent, the preparation method further comprises: applying a sizing agent to at least one side of the surface of the impregnated carbon fiber layer to form a sizing agent layer; and the sizing agent comprises irregular flaky powder sizing agent.

[0055] Before the toughening layer is bonded to the surface of at least one side of the impregnated carbon fiber layer by the sizing agent, irregular flaky powder sizing agent is applied to the surface of at least one side of the impregnated carbon fiber layer to form a sizing agent layer, which can on the one hand size and toughen the carbon fiber layer itself, and on the other hand bond the toughening layer to the surface of at least one side of the carbon fiber layer to further size and toughen the carbon fiber layer.

[0056] For example, when irregular flaky powder sizing agent is applied to the surface of one side of the impregnated carbon fiber layer to form a sizing agent layer, the sizing agent layer is used to bond the toughening layer while sizing and toughening the carbon fiber layer. When irregular flaky powder sizing agent is applied to both surfaces of the impregnated carbon fiber layer to form sizing agent layers, the sizing agent layer on one surface is used to bond the toughening layer, and the sizing agent layer on the other surface has moderate and stable adhesion and can be used for interlayer bonding during automatic fiber tape laying, ensuring that the laid layer can be temporarily adhered to the underlying layer or mold to resist gravity, laying pressure and shear force, and prevent displacement, wrinkling or separation. At the same time, the irregular flaky powder sizing agent does not completely cover the carbon fiber layer, leaving a flow channel for the resin in the thickness direction of the carbon fiber composite preform during the preparation of the preform, allowing low-viscosity liquid resin to quickly and uniformly penetrate the entire preform. The fiber tape with moderate surface viscosity after heating also helps to improve the stability of the preform.

[0057] In an exemplary embodiment, the method of bonding the toughening layer to the surface of at least one side of the impregnated carbon fiber layer to form a fiber tape includes: bonding the toughening layer to the side of the sizing agent layer away from the impregnated carbon fiber layer, and hot pressing the impregnated carbon fiber layer and the toughening layer under second preset conditions to make the impregnated carbon fiber layer and the toughening layer tightly composite to obtain the fiber tape, and winding the fiber tape.

[0058] In this embodiment, the toughening layer is bonded to the side of the sizing agent layer away from the impregnated carbon fiber layer, and the impregnated carbon fiber layer and the toughening layer are hot pressed, which makes the sizing agent melt and flow and penetrate to ensure that the impregnated carbon fiber layer and the toughening layer are in close contact and composite. The toughening layer is bonded to one side of the impregnated carbon fiber layer under the action of the sizing agent, which can on the one hand size the impregnated carbon fiber layer, and on the other hand, the toughening layer has open pores or network, which can leave a flow channel for the resin in the thickness direction of the carbon fiber composite preform during the preparation of the preform, allowing low-viscosity liquid resin to quickly and uniformly penetrate the entire preform, and play a role in flow guiding and venting.

[0059] In an exemplary embodiment, the second preset conditions include: In the first hot pressing stage, the second preset temperature is 75-110°C, and the first preset pressure is 0.5-0.9 MPa. The second heat pressing stage is at a third preset temperature of 95-130 °C and a second preset pressure of 1.1-1.6 MPa. The third heat pressing stage is at a fourth preset temperature of 115-140 °C and a third preset pressure of 1.7-2.3 MPa.

[0060] The toughening layer is bonded to the side of the sizing agent layer away from the impregnated carbon fiber layer, and the impregnated carbon fiber layer and the toughening layer are subjected to three-stage heat pressing, wherein the first heat pressing stage at a low temperature (75-110 °C) and a low pressure (0.5-0.9 MPa) can make the sizing agent preliminarily soften and flow, and begin to infiltrate the toughening layer and the impregnated carbon fiber layer, thereby avoiding sudden high temperature leading to degradation of the sizing agent or interlayer stress. For example, the second preset temperature in the first heat pressing stage can be 75 °C, 90 °C or 110 °C, and the second preset temperature in the first heat pressing stage can also be any value between the example temperatures, for example, the second preset temperature in the first heat pressing stage can be any value between 85-100 °C. For example, the first preset pressure in the first heat pressing stage can be 0.5 MPa, 0.7 MPa or 0.9 MPa, and the first preset pressure in the first heat pressing stage can also be any value between the example pressures, for example, the first preset pressure in the first heat pressing stage can be any value between 0.6-0.8 MPa. For example, the duration of the first heat pressing stage can be 30-90 seconds, for example, the duration of the first heat pressing stage can be 30 seconds, 60 seconds or 90 seconds, and the duration of the first heat pressing stage can also be any value between the example durations, for example, the duration of the first heat pressing stage can be any value between 40-80 seconds.

[0061] The second hot pressing stage under medium temperature (95-130 °C) and medium pressure (1.1-1.6 MPa) further promotes the melting and cross-linking of the sizing agent, ensuring sufficient penetration and interfacial bonding in the toughening layer and the impregnated carbon fiber layer, and the increase in pressure helps to remove bubbles and voids. For example, the third preset temperature under the second hot pressing stage can be 95 °C, 110 °C or 130 °C, and the third preset temperature under the second hot pressing stage can also be any value between the example temperatures, for example, the third preset temperature under the second hot pressing stage can be any value between 105-120 °C. For example, the second preset pressure under the second hot pressing stage can be 1.1 MPa, 1.3 MPa or 1.6 MPa, and the second preset pressure under the second hot pressing stage can also be any value between the example pressures, for example, the second preset pressure under the second hot pressing stage can be any value between 1.2-1.4 MPa. For example, the duration of the second hot pressing stage can be 60-180 seconds, for example, the duration of the second hot pressing stage can be 60 seconds, 120 seconds or 180 seconds, and the duration of the second hot pressing stage can also be any value between the example durations, for example, the duration of the second hot pressing stage can be any value between 90-150 seconds.

[0062] The third hot pressing stage under high temperature (115-140 °C) and high pressure (1.7-2.3 MPa) completes the final curing and cross-linking of the sizing agent, forming a strong bonding layer (i.e. sizing agent layer) and optimizing the mechanical properties (such as interlaminar shear strength and impact resistance) of the fiber tape. For example, the fourth preset temperature under the third hot pressing stage can be 115 °C, 120 °C or 140 °C, and the fourth preset temperature under the third hot pressing stage can also be any value between the example temperatures, for example, the fourth preset temperature under the third hot pressing stage can be any value between 120-135 °C. For example, the third preset pressure under the third hot pressing stage can be 1.7 MPa, 2.0 MPa or 2.3 MPa, and the third preset pressure under the third hot pressing stage can also be any value between the example pressures, for example, the third preset pressure under the third hot pressing stage can be any value between 1.8-2.1 MPa. For example, the duration of the third hot pressing stage can be 120-300 seconds, for example, the duration of the third hot pressing stage can be 120 seconds, 200 seconds or 300 seconds, and the duration of the third hot pressing stage can also be any value between the example durations, for example, the duration of the third hot pressing stage can be any value between 150-250 seconds.

[0063] In an example embodiment, the fiber tape provided by the present disclosure can be physically cut into dry fiber wide tapes, narrow tapes of different widths, and hand-laid, tape-laid, and filament-laid materials can be obtained.

[0064] The example embodiment of the present disclosure provides a fiber tape preparation device for preparing the fiber tape as described above. The fiber tape preparation device includes, for example, A yarn spreading module includes a unwinding device, a composite slot roller, and a heating and vibrating yarn spreading system, which are used to unwind and spread the carbon fibers to form a carbon fiber layer. The composite slot roller includes a first slot roller and a second slot roller, which are installed laterally offset to arrange the carbon fiber strands in layers.

[0065] A sizing module includes an emulsion tank and a storage tank, and a hot air circulation oven. The sizing module is used to impregnate the carbon fiber layer with an emulsion sizing agent, dry the water in the carbon fiber layer, and heat and soften the water-soluble epoxy resin. An end sizing roller is provided at the outlet of the emulsion tank. The end sizing roller recovers excess emulsion sizing agent on the carbon fiber layer and pumps the excess emulsion sizing agent to the storage tank through a circulating pump. The emulsion tank and the storage tank form a closed-loop circulation system for the emulsion sizing agent.

[0066] A powder scattering module is used to apply irregular flaky powder sizing agent to at least one side of the carbon fiber layer and heat and soften the irregular flaky powder sizing agent. The powder scattering module includes a front powder scattering module, a turnover module, and a back powder scattering module. The front powder scattering module includes a powder scattering device with a vibrating brush system, a paper attaching device, and a hot pressing device. The irregular flaky powder sizing agent is applied to the front of the carbon fiber layer, the release paper is attached to prevent the sizing agent from sticking to the roller, and the front sizing agent of the carbon fiber layer is heated and softened by hot pressing. The turnover module includes a two-layer guide roller structure, a transition guide roller module, and a one-layer guide roller structure. The carbon fiber layer is turned from two layers to one layer, so that the operation surface of the carbon fiber layer changes from the front to the back. The back powder scattering module includes a powder scattering device with a vibrating brush system, a yarn attaching device, and a hot pressing device. The irregular flaky powder sizing agent is applied to the back of the carbon fiber layer, and the toughening layer is attached. The toughening layer is bonded to the back of the carbon fiber layer by hot pressing. The yarn attaching device includes an alternating current servo motor and an angular displacement sensor, which are used to control the unwinding speed of the toughening layer to eliminate composite defects caused by slippage between the toughening layers.

[0067] A sizing module includes a far infrared heating oven and a hot pressing device. The sizing module is used to heat and press the carbon fiber layer and the toughening layer to tightly composite the carbon fiber layer and the toughening layer, and obtain the fiber tape.

[0068] A winding module is used to wind the fiber tape.

[0069] In order to more clearly explain the technical solutions provided by the example embodiments of the present disclosure, the fiber tape preparation method provided by the example embodiments of the present disclosure is used to prepare the fiber tape provided by the example embodiments of the present disclosure.

[0070] The embodiment is the preparation of aerospace-grade high-strength fiber tape (T800, 24K, 194g / m²), which is suitable for the main load-bearing structure of commercial aircraft.

[0071] The 48-axis T800-grade 24K carbon fiber is unwound under constant tension, combed, and spread to form a carbon fiber layer.

[0072] After the carbon fiber layer is immersed in the emulsion sizing agent, it is dried and heated at 140-190°C with a wind speed of 0.8-2.0m / s for 30-60s to obtain a sized carbon fiber layer.

[0073] On the front and back surfaces of the sized carbon fiber layer, irregular flaky powder sizing agent is applied to form a sizing agent layer, and on the back surface of the sized carbon fiber layer, a toughening layer is bonded. The sized carbon fiber layer and the toughening layer are subjected to three-stage hot pressing sizing, wherein the three-stage hot pressing sizing: first hot pressing stage, temperature 75-110°C, pressure 0.5-0.9 MPa; second hot pressing stage, temperature 95-130°C, pressure 1.1-1.6 MPa; third hot pressing stage, temperature 115-140°C, pressure 1.7-2.3 MPa. The sized carbon fiber layer and the toughening layer are tightly combined to obtain a fiber tape, which is wound. Figure 2 The cross-sectional structure of the fiber tape is shown, and the fiber tape 100 includes a carbon fiber layer 10, a toughening layer 20, an emulsion sizing agent 30, and a sizing agent 40. Figure 3 The back view of the fiber tape is shown, Figure 4 The front view of the fiber tape is shown.

[0074] In Examples 1-12, the fiber tapes were prepared according to the method in the specific examples above, and the amounts of the components in the fiber tapes were adjusted. The fiber tapes prepared in Examples 1-12 were used to prepare unidirectional laminates, and their mechanical properties were measured: The fiber tape was cut into a 220mm 250mm rectangle, and then a hot press was used to prepare a preform with 5 layers (0 degree direction), 10 layers (0 degree direction), and 24 layers ([45, 0, -45, 90]6) of the fiber tape laid respectively, followed by a vacuum-assisted resin infusion molding process to prepare a unidirectional carbon fiber reinforced epoxy resin-based composite laminate.

[0075] The above 5-layer unidirectional carbon fiber reinforced epoxy resin-based composite laminate was prepared into a tensile test sample according to ASTM D3039 standard, and a compression test sample was prepared according to SACMA SRM01R-94 standard, and the tensile and compression properties of the obtained material were tested respectively.

[0076] The 10-layer unidirectional carbon fiber reinforced epoxy resin-based composite laminated plate described above was made into a short beam interlaminar shear test sample according to the ASTM D2344 standard, and the interlaminar shear strength of the obtained material was tested.

[0077] The 24-layer carbon fiber reinforced epoxy resin-based composite laminated plate described above was made into an impact compression strength test sample according to the ASTM D7173 standard, and the impact compression strength of the obtained material was tested. See Table 1 for details: Table 1

[0078] Table 1 (continued)

[0079] In addition, the fiber tape to which a common powder sizing agent was applied was used as Comparative Example 1, and a carbon fiber reinforced epoxy resin-based composite laminated plate was prepared according to the above method, and the 0° tensile strength of the 5-layer laminated plate was 2050 MPa, the 0° tensile modulus of the 5-layer laminated plate was 85 GPa, the 0° compression strength of the 5-layer laminated plate was 876 MPa, the interlaminar shear strength of the 10-layer laminated plate was 59 MPa, and the impact compression strength of the 24-layer laminated plate was 183 MPa. It can be seen that the fiber tape prepared by the preparation method of the fiber tape provided by the exemplary embodiments of the present disclosure causes a stable shape and high interlaminar adhesion, and thus the carbon fiber reinforced composite material prepared therefrom has excellent mechanical properties.

[0080] The above description can be implemented individually or in various combinations, and these variations are within the protection scope of the present disclosure.

[0081] Finally, it should be noted that in this document, the terms "comprise", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device containing a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device.

[0082] The above examples are only used to illustrate the technical solutions of the present disclosure, and not to limit them. Although the present disclosure has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A fibrous band, characterized in that, The fiber tape comprises: a carbon fiber layer, the carbon fiber layer being filled with an emulsion sizing agent in the gaps; a toughening layer being bonded to the surface of at least one side of the carbon fiber layer by the sizing agent; the sizing agent comprising irregular flaky powder sizing agent.

2. The fiber ribbon of claim 1, wherein, The mass of the emulsion sizing agent is 0.8-3.2% of the mass of the carbon fiber layer; the emulsion sizing agent comprises the following components, and the content of each component is represented as follows in mass fraction: water-soluble epoxy resin 0.4-2.6 parts, composite surfactant 0.1-1.3 parts, deionized water 4.1-6.9 parts; The composite surfactant comprises non-ionic surfactant and anionic surfactant, and the mass ratio of the non-ionic surfactant to the anionic surfactant is (1.5-4):1; The molecular weight distribution Mw / Mn of the water-soluble epoxy resin is 1.4-2.2, and the epoxy equivalent weight is 150-250 g / eq.

3. The fiber ribbon of claim 1, wherein, The mass of the sizing agent is 5.6-8.5% of the mass of the carbon fiber layer; the sizing agent comprises the following components, and the content of each component is represented as follows in mass fraction: reactive epoxy resin 25-48 parts, non-reactive epoxy resin 52-75 parts.

4. The fiber ribbon according to claim 1 or 3, characterized by The sizing agent is arranged on the surface of at least one side of the carbon fiber layer to form a sizing agent layer.

5. The fiber ribbon of claim 1, wherein, The toughening layer comprises a self-supporting porous structure; the unit area weight of the toughening layer is 6-20 g / m 2 , and the thickness is ≤70 μm.

6. The fiber ribbon of claim 4, wherein, The carbon fiber layer comprises a carbon fiber unidirectional tape layer composed of a plurality of carbon fiber single yarns; The volume fraction of the carbon fiber single yarn in the fiber tape is 50% to 60%; the weight per unit area of the carbon fiber layer is 170 to 210 g / m 2 ; the thickness ratio of the carbon fiber layer to the toughening layer is (8.5 to 36.4):

1.

7. A method of producing a fiber tape, characterized by, The preparation method is used for preparing the fiber tape as claimed in any one of claims 1-6; the preparation method comprises: immersing the carbon fiber layer in the emulsion sizing agent, drying and heating under first preset conditions to obtain a sizing carbon fiber layer; bonding the toughening layer to the surface of at least one side of the sizing carbon fiber layer by the sizing agent to form the fiber tape.

8. The method of producing a fiber ribbon according to claim 7, characterized by, Before the bonding of the toughening layer to the surface of at least one side of the sizing carbon fiber layer by the sizing agent, the preparation method further comprises: applying the sizing agent to the surface of at least one side of the sizing carbon fiber layer to form a sizing agent layer; the sizing agent comprises irregular flaky powder sizing agent.

9. The method of producing a fiber ribbon according to claim 8, characterized by, The bonding of the toughening layer to the surface of at least one side of the sizing carbon fiber layer by the sizing agent to form the fiber tape comprises: bonding the toughening layer to the side of the sizing agent layer away from the sizing carbon fiber layer, and heat-pressing and sizing the sizing carbon fiber layer and the toughening layer under second preset conditions to make the sizing carbon fiber layer and the toughening layer tightly composite to obtain the fiber tape, and winding the fiber tape.

10. The method of producing a fiber ribbon according to claim 9, characterized by, The first preset conditions comprise: first preset temperature 140-190℃, preset wind speed 0.8-2.0m / s, and first preset time length 30-60s; The second preset conditions comprise: first heat-pressing stage, second preset temperature 75-110℃, and first preset pressure 0.5-0.9 MPa; second heat-pressing stage, third preset temperature 95-130℃, and second preset pressure 1.1-1.6 MPa; third heat-pressing stage, fourth preset temperature 115-140℃, and third preset pressure 1.7-2.3 MPa.

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