A flame-retardant fiber-reinforced resin matrix composite material, its preparation method and application
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI UNIV
- Filing Date
- 2026-05-29
- Publication Date
- 2026-06-30
Smart Images
Figure CN122300007A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of flame-retardant composite materials technology, and in particular to a flame-retardant fiber-reinforced resin-based composite material, its preparation method, and its application. Background Technology
[0002] Fiber-reinforced resin matrix composites, with their excellent properties such as lightweight and high specific strength, are widely used in aerospace, transportation, and other fields. Currently, the main method for preparing flame-retardant fiber-reinforced resin matrix composites is to directly add solid flame retardants to the resin matrix, followed by hot pressing or manual layup processes. However, physically mixed additive flame retardants often face problems such as agglomeration and migration, which reduce the flame-retardant and mechanical properties of the composite material and limit the development of composite material preparation processes. Vacuum induction molding (VIP) technology, compared to manual layup, offers advantages such as more uniform molding quality, lower porosity, and greater suitability for integrated molding of large and complex structural components, and is widely used in the production of large structural parts in aerospace manufacturing, shipbuilding, and wind power generation. However, adding solid flame retardants in the VIP process still faces a dual challenge: on the one hand, solid flame retardants significantly increase the viscosity of the resin matrix and reduce its flowability; on the other hand, the filtering effect of the fiber fabric on the flame retardant causes it to accumulate on the surface of the distribution medium, hindering resin flow and fiber impregnation.
[0003] For example, patent CN116198144 A discloses a fiber-reinforced resin-based composite material, including a fiber / resin composite material and a flame-retardant nanofiber membrane toughening layer inserted therein. The flame-retardant nanofiber membrane is composed of nanofibers, which are composed of thermoplastic polymer fiber bodies and flame retardants dispersed therein. However, the content of the flame retardant in the nanofibers is only 5-50 wt%, and the proportion of the flame-retardant nanofiber membrane in the fiber-reinforced resin-based composite material is only 0.1-5 wt%, resulting in limited flame-retardant performance. Summary of the Invention
[0004] The purpose of this invention is to provide a flame-retardant fiber-reinforced resin matrix composite material, its preparation method and application, which has both high flame-retardant properties and excellent mechanical properties.
[0005] The objective of this invention can be achieved through the following technical solutions: One objective of this invention is to provide a flame-retardant fiber-reinforced resin-based composite material, comprising a composite material layer made of reinforcing fiber fabric and resin, and a nanofiber flame retardant layer intercalated between the composite material layers. Each nanofiber flame retardant layer is composed of a plurality of nanofiber flame retardants arranged randomly and alternately, and the nanofiber flame retardants are composed of a polymer flame retardant, a low-molecular-weight flame retardant and an ionic liquid.
[0006] Preferably, the flame-retardant fiber-reinforced resin matrix composite material has a porosity of 0.5~1.5% and a thickness of 2~4 mm.
[0007] More preferably, the thickness of the flame-retardant fiber-reinforced resin matrix composite material is 2.9~3.1 mm.
[0008] In this invention, the thickness of the flame-retardant fiber-reinforced resin matrix composite material can be controlled by adjusting the number of layers of reinforcing fiber fabric according to the requirements of specific testing standards, and the thickness is usually 2~5 mm.
[0009] Preferably, the thickness of the nanofiber flame retardant layer is 10-120 μm, the porosity is 50-95%, and the areal density is 3-20 g / m³. 2 .
[0010] Preferably, the thickness of the nanofiber flame retardant layer is 20-60 μm, the porosity is 65-90%, and the areal density is 4-18 g / m³. 2 .
[0011] More preferably, the interlaminar shear strength of the flame-retardant fiber-reinforced resin matrix composite material is 60~90 MPa.
[0012] The flame-retardant fiber-reinforced resin matrix composite material of this invention is prepared based on a vacuum infiltration (VIP) process. Compared to existing technologies using physically mixed flame retardants or polyurethane nanofiber membranes, this invention employs a nanofiber-like flame retardant layer composed entirely of flame-retardant components. Furthermore, through interlayer placement, it does not affect the wetting of the reinforcing fibers by the matrix resin. Due to its molding characteristics, this composite material retains the inherent properties of low porosity and high mechanical strength of similar VIP-molded composite materials (i.e., it does not significantly degrade the original mechanical properties).
[0013] Preferably, the diameter of the nanofiber flame retardant is 100~600 nm.
[0014] Preferably, the diameter of the nanofiber flame retardant is 200~500 nm.
[0015] Preferably, the flame-retardant fiber-reinforced resin matrix composite material comprises the following components by mass fraction: 30-40 wt% of resin 40-65 wt% of reinforcing fiber fabric Nanofiber flame retardant 5~20 wt%.
[0016] Preferably, the nanofiber flame retardant comprises the following components by mass fraction: 55-75 wt% of polymeric flame retardant; Low molecular weight flame retardant 20~40 wt% Ionic liquid 3~10 wt%.
[0017] More preferably, the nanofiber flame retardant comprises the following components by mass fraction: 58-70 wt% of polymeric flame retardant Low molecular weight flame retardant 22~35 wt% Ionic liquid 4~8 wt%.
[0018] Preferably, the resin is any one of epoxy resin, phenolic resin, isocyanate, vinyl resin, and unsaturated resin.
[0019] More preferably, the viscosity of the resin is 100~2000 mPa·s.
[0020] Preferably, the reinforcing fiber fabric is any one of carbon fiber fabric, glass fiber fabric, aramid fiber fabric, and basalt fiber fabric.
[0021] More preferably, the basis weight of the reinforcing fiber fabric is 150~250 g / m². 2 .
[0022] Preferably, the weight-average molecular weight of the polymeric flame retardant is 50,000 to 150,000.
[0023] Preferably, the molecular weight of the low-molecular-weight flame retardant is 100-2000.
[0024] More preferably, the molecular weight ratio of the polymeric flame retardant to the low-molecular-weight flame retardant is ≥50 (1.7 orders of magnitude).
[0025] In this invention, the high molecular weight flame retardant must have sufficient fiber-forming ability, while the low molecular weight flame retardant exists as a low molecular weight dispersed phase. When the molecular weights of the two differ by more than 1.7 orders of magnitude, the low molecular weight component is easily embedded in the high molecular weight chain network and is uniformly coated under electric field stretching, ultimately obtaining fibers with smooth surfaces and uniform diameters.
[0026] Preferably, the polymeric flame retardant is a brominated polymeric flame retardant.
[0027] More preferably, the polymeric flame retardant is any one of brominated SBS (brominated styrene-butadiene-styrene triblock copolymer), brominated PS (brominated polystyrene), and brominated pentabromobenzyl polyacrylate.
[0028] Preferably, the low-molecular-weight flame retardant is a phosphorus-containing flame retardant.
[0029] More preferably, the low-molecular-weight flame retardant is any one or more of ammonium polyphosphate, resorcinol bis(diphenyl phosphate), pentaerythritol phosphate, dimethyl methylphosphonate, and triphenyl phosphate.
[0030] Preferably, the ionic liquid is any one or more of quaternary phosphonium ionic liquids, quaternary ammonium ionic liquids, and imidazole ionic liquids.
[0031] In this invention, the preferred polymeric flame retardant is a brominated polymeric flame retardant, and the preferred low-molecular-weight flame retardant is a phosphorus-containing flame retardant. The combination of the two flame retardants can exert a synergistic flame retardant effect of bromine and phosphorus, resulting in more efficient flame retardancy.
[0032] More preferably, the ionic liquid contains phosphorus and / or bromine flame retardant elements, specifically one or more of tetrabutylphosphonium bromide, 1-ethyl-3-methylimidazolium diethyl phosphate, propyltributylphosphonium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylimidazolium bromide.
[0033] The second objective of this invention is to provide a method for preparing the aforementioned flame-retardant fiber-reinforced resin-based composite material, comprising the following steps: S1: Dissolve a high molecular weight flame retardant, a low molecular weight flame retardant, and an ionic liquid in an organic solvent to obtain a flame retardant electrospinning solution; S2: Using reinforced fiber fabric as the collection substrate, a nanofiber-like flame retardant layer is prepared on the surface of the reinforced fiber fabric through electrospinning process; S3: Lay up the reinforcing fiber fabric containing the nanofiber flame retardant layer, inject resin according to the mass ratio through a vacuum infusion process, and obtain the flame retardant fiber reinforced resin matrix composite material after curing.
[0034] Preferably, in step S1, the content of the high molecular weight flame retardant in the flame retardant electrospinning solution is 15-40 wt%, the content of the low molecular weight flame retardant is 5-15 wt%, the content of the ionic liquid is 1-5 wt%, and the content of the organic solvent is 40-80 wt%.
[0035] Preferably, in step S1, the organic solvent is any one or more of dimethylacetamide, dimethylformamide, methylpyrrolidone, toluene, and tetrahydrofuran.
[0036] Preferably, in step S2, the process parameters of the electrospinning process include: an electrospinning ambient temperature of 20~28℃, a humidity of 20~40%, a spinning voltage of 20~60 kV, and a winding speed of 15~60 mm / min.
[0037] Preferably, in step S3, the process parameters of the vacuum induction process include: a vacuum degree of -0.095 MPa to -0.100 MPa and an infusion temperature of 5 to 100°C.
[0038] The third objective of this invention is to provide an application of the aforementioned flame-retardant fiber-reinforced resin matrix composite material, which is used to manufacture structural components in the fields of aerospace, shipbuilding, wind power generation, and transportation materials technology.
[0039] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a flame-retardant fiber-reinforced resin-based composite material, which is composed of nanofiber flame retardant layers intercalated and distributed in the interlayer formed by reinforcing fiber fabric and resin composite, and each nanofiber flame retardant layer is formed by a random staggered arrangement of several nanofiber flame retardants; the nanofiber flame retardant is prepared by composite of high molecular flame retardant, low molecular flame retardant and ionic liquid, so that the composite material has both excellent flame retardant properties and good mechanical properties.
[0040] (2) This invention breaks through the traditional flame retardant mode of directly dispersing flame retardants in the matrix resin, and innovatively adopts a structural design of preparing flame retardants into nanofibers and placing them between the layers of composite materials. Utilizing the small-scale characteristics and high porosity of nanofibers, during the vacuum induction molding process, this nanofiber layer does not affect the flow characteristics of the matrix resin or the wetting effect on the reinforcing fibers, effectively avoiding the adverse interference of traditional flame retardant methods on the vacuum induction process. At the same time, compared with the traditional hot pressing molding process (which produces composite materials with high porosity, approximately 3.5%), this invention has high compatibility with the vacuum induction process, enabling the integrated low-porosity molding of large and complex structural parts, thus expanding the application scenarios of composite materials.
[0041] (3) The nanofibers prepared by this invention are composed of pure flame retardant components and do not require thermoplastic polymers (such as polyurethane, phenoxy resin, etc.) as fiber substrates, making them true nanofiber flame retardants. This design not only simplifies the preparation process but also significantly improves the flame retardant efficiency, ensuring stable and reliable flame retardant effects, and has the advantages of simple process and outstanding flame retardant performance.
[0042] (4) This invention selects a high molecular weight flame retardant with sufficient fiber-forming ability and introduces a low molecular weight flame retardant in the form of a low molecular weight dispersed phase. When the molecular weights of the two differ by more than 1.7 orders of magnitude, the low molecular weight component can be embedded in the polymer chain network and uniformly coated under the stretching action of an electric field, thereby preparing nanofibers with smooth surfaces and uniform diameters. At the same time, the high molecular weight flame retardant is preferably a brominated high molecular weight flame retardant, and the low molecular weight flame retardant is preferably a phosphorus-containing flame retardant. The combination of the two flame retardants can exert a synergistic flame retardant effect of bromine and phosphorus, making the flame retardant more efficient. In contrast, in the existing technology, the polymer is used as the fiber body, and the flame retardant is only used as a small amount of additive (usually less than 5 wt%) for physical mixing and dispersion. Not only is the total proportion of flame retardant low and the flame retardant efficiency limited, but it is also prone to problems such as agglomeration and uneven distribution, resulting in unstable flame retardant effect. Moreover, the spinnability and fiber morphology are highly dependent on the specific polymer / flame retardant ratio, and the universality is poor. In comparison, this invention employs a nanofiber design with all flame retardant components, maximizing the flame retardant content. At the same time, through interlayer intercalation, it achieves excellent flame retardant performance and uniform flame retardant distribution without degrading the original mechanical properties of the composite material.
[0043] (5) Although brominated polystyrene and other brominated polymeric flame retardants have a certain molecular weight, the presence of bromine leads to high interfacial tension, strong intermolecular forces, poor conductivity, and poor compatibility with organic solvents. If the spinning solution only contains polymeric and low-molecular-weight flame retardants (without ionic liquids), the jet cannot be fully stretched, and stable nanofibers cannot be prepared. In some cases, the yield is extremely low, and fiber formation is impossible, resulting in extremely poor spinnability. To address this problem, this invention introduces ionic liquids into the spinning solution. By using ionic liquids, the conductivity of the spinning solution is improved, intermolecular forces and surface tension are reduced, thereby effectively improving the spinnability of the spinning solution. At the same time, the morphology of the spun nanofibers is optimized to ensure the forming quality of the nanofiber flame retardant layer. Attached Figure Description
[0044] Figure 1 The image shows a SEM image of the nanofiber flame retardant in Example 1 (scale bar is 3 μm).
[0045] Figure 2 The image shows a SEM image of the nanofiber flame retardant in Comparative Example 4 (scale bar is 3 μm). Detailed Implementation
[0046] This embodiment is implemented based on the technical solution of the present invention, and provides detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiment.
[0047] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.
[0048] This invention provides a flame-retardant fiber-reinforced resin-based composite material, comprising a composite material layer composed of reinforcing fiber fabric and resin, and a nanofiber flame retardant layer intercalated between the composite material layers. Each nanofiber flame retardant layer is composed of a plurality of nanofiber flame retardants arranged randomly and alternately, and the nanofiber flame retardants are composed of a polymer flame retardant, a low-molecular-weight flame retardant and an ionic liquid.
[0049] The flame-retardant fiber-reinforced resin matrix composite material has a porosity of 0.5–1.5%, a thickness of 2–4 mm, and an interlaminar shear strength of 60–90 MPa; the nanofiber flame retardant layer has a thickness of 10–120 μm, a porosity of 50–95%, and an areal density of 3–20 g / m³. 2 The diameter of the nanofiber flame retardant is 100~600 nm.
[0050] The flame-retardant fiber-reinforced resin matrix composite material comprises the following components by mass fraction: 30-40 wt% of resin 40-65 wt% of reinforcing fiber fabric Nanofiber flame retardant 5~20 wt%.
[0051] The resin is any one of epoxy resin, phenolic resin, isocyanate, vinyl resin, and unsaturated resin, and the resin viscosity is 100~2000 mPa·s; the reinforcing fiber fabric is any one of carbon fiber fabric, glass fiber fabric, aramid fiber fabric, and basalt fiber fabric.
[0052] The nanofiber flame retardant comprises the following components by mass fraction: 55-75 wt% of polymeric flame retardant; Low molecular weight flame retardant 20~40 wt% 3~10 wt% ionic liquid The polymeric flame retardant has a weight-average molecular weight of 50,000 to 150,000, the low molecular weight flame retardant has a molecular weight of 100 to 2,000, and the molecular weight ratio of the polymeric flame retardant to the low molecular weight flame retardant is ≥50.
[0053] Specifically, the polymeric flame retardant is any one of brominated SBS, brominated PS, and brominated pentabromobenzyl polyacrylate; the low-molecular-weight flame retardant is a phosphorus-containing flame retardant; and the ionic liquid is any one or more of quaternary phosphonium ionic liquids, quaternary ammonium ionic liquids, and imidazole ionic liquids.
[0054] The preparation method of the flame-retardant fiber-reinforced resin matrix composite material includes the following steps: S1: A high molecular weight flame retardant, a low molecular weight flame retardant, and an ionic liquid are dissolved in an organic solvent to obtain a flame retardant electrospinning solution; wherein the content of the high molecular weight flame retardant in the flame retardant electrospinning solution is 15-40 wt%, the content of the low molecular weight flame retardant is 5-15 wt%, the content of the ionic liquid is 1-5 wt%, and the content of the organic solvent is 40-80 wt%, wherein the organic solvent is any one or more of dimethylacetamide, dimethylformamide, methylpyrrolidone, toluene, and tetrahydrofuran.
[0055] S2: Using reinforced fiber fabric as the collection substrate, a nanofiber-like flame retardant layer is prepared on the surface of the reinforced fiber fabric by electrospinning process; the process parameters of the electrospinning process include: electrospinning ambient temperature of 20~28℃, humidity of 20~40%, spinning voltage of 20~60 kV, and winding speed of 15~60 mm / min.
[0056] S3: Lay up the reinforcing fiber fabric containing the nanofiber flame retardant layer, inject resin according to the mass ratio through a vacuum infusion process, and obtain the flame retardant fiber reinforced resin matrix composite material after curing. The process parameters of the vacuum infusion process include: vacuum degree of -0.095 MPa to -0.100 MPa, and injection temperature of 5 to 100 °C.
[0057] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0058] In the following embodiments, the relevant performance testing methods are as follows: the limiting oxygen index is tested according to GB / T 8924-2005 standard; the vertical burning performance is tested according to ASTM D3801 standard; and the interlaminar shear strength is tested according to GB / T 30969-2014 standard.
[0059] Examples 1-3 The following embodiments all provide a method for preparing flame-retardant fiber-reinforced resin matrix composites, as detailed below: 25 wt% of high molecular weight flame retardant (brominated SBS: Shandong Rixing New Material Co., Ltd., RX-971, weight average molecular weight M) was added. w =115596), 10 wt% low molecular weight flame retardant (ammonium polyphosphate: molecular weight M r=1490) and 2 wt% ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) were dissolved in 63 wt% organic solvent (dimethylacetamide). The electrospinning environment temperature (26℃), humidity (30%), and spinning voltage (60 kV) were adjusted. The carbon fiber fabric (manufacturer: Jiangsu Hengshen Co., Ltd., grade: T300, 3K, 240 g / m) was then used. 2 The nanofiber flame-retardant layer was directly formed on the fabric surface by electrospinning after being adhered to the collection substrate. Subsequently, 14 layers of carbon fiber fabric with nanofiber flame retardant were laminated and laid out. Epoxy resin (manufacturer: East China University of Science and Technology Huachang Polymer Co., Ltd., brand name: MERICAN® 3312A / B) was injected through vacuum at 80°C under vacuum. After curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate was obtained.
[0060] Example 1 By adjusting the electrospinning winding speed to 25 mm / min, a nanofiber flame-retardant layer of approximately 60 μm thickness is directly formed on the surface of the reinforcing fiber fabric; after curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate of 3.05 mm thickness is obtained.
[0061] Example 2 By adjusting the electrospinning winding speed to 35 mm / min, a nanofiber flame-retardant layer of approximately 40 μm thickness is directly formed on the surface of the reinforcing fiber fabric; after curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate of 3.02 mm thickness is obtained.
[0062] Example 3 By adjusting the electrospinning winding speed to 40 mm / min, a nanofiber flame-retardant layer of approximately 20 μm thickness is directly formed on the surface of the reinforcing fiber fabric; after curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate of 2.97 mm thickness is obtained.
[0063] In Examples 1-3, the mass fractions of the nanofiber flame retardant layer, carbon fiber, and epoxy resin are shown in Table 1.
[0064] Table 1 The flame-retardant carbon fiber reinforced epoxy resin matrix composite laminates prepared in Examples 1-3 were engraved into standard test strips according to ASTM and GB / T standard dimensions, and their properties were tested as follows. The results are shown in Table 2.
[0065] Table 2 As shown in Table 2, with the increase of the thickness of the nanofiber flame retardant layer, that is, the increase of the flame retardant content in the composite material, the flame retardant performance of the composite material is gradually improved; at the same time, all embodiments have excellent interlaminar shear strength and good mechanical strength.
[0066] Figure 1 The image shows an SEM image of the nanofiber flame retardant prepared in Example 1. As can be seen from the image, the diameter of the prepared nanofiber flame retardant is about 400 nm, and several nanofiber flame retardants are randomly arranged in an alternating pattern.
[0067] Examples 4-6 The following embodiments all provide a method for preparing flame-retardant fiber-reinforced resin matrix composites, as detailed below: Add 25 wt% of high molecular weight flame retardant (brominated polystyrene: Shandong Tianyi Chemical Co., Ltd., 7010, M) w =74491), 15 wt% low molecular weight flame retardant (pentaerythritol phosphonate: M r =180.05) and 2 wt% ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) were dissolved in 63 wt% organic solvent (dimethylacetamide). The electrospinning environment temperature (26℃), humidity (30%), and spinning voltage (60 kV) were adjusted, and carbon fiber fabric was adhered to the collection substrate, directly forming a nanofiber flame-retardant layer on the fabric surface. Fourteen layers of carbon fiber fabric coated with nanofiber flame retardant were laminated, and epoxy resin was infused through vacuum infusion. After curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate was obtained.
[0068] Example 4 By adjusting the electrospinning winding speed to 20 mm / min, a nanofiber flame-retardant layer of approximately 60 μm thickness is directly formed on the surface of the reinforcing fiber fabric; after curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate of 3.03 mm thickness is obtained.
[0069] Example 5 By adjusting the electrospinning winding speed to 30 mm / min, a nanofiber flame-retardant layer of approximately 40 μm thickness is directly formed on the surface of the reinforcing fiber fabric; after curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate of 3.03 mm thickness is obtained.
[0070] Example 6 By adjusting the electrospinning winding speed to 40 mm / min, a nanofiber flame-retardant layer of approximately 20 μm thickness is directly formed on the surface of the reinforcing fiber fabric; after curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate of 3.01 mm thickness is obtained.
[0071] In Examples 4-6, the mass fractions of the nanofiber flame retardant layer, carbon fiber, and epoxy resin are shown in Table 3.
[0072] The flame-retardant carbon fiber reinforced epoxy resin matrix composite laminates prepared in Examples 4-6 were engraved into standard test strips according to ASTM and GB / T standard dimensions, and their properties were tested as follows. The results are shown in Table 4.
[0073] Table 3 Table 4 Examples 7-9 The following embodiments all provide a method for preparing flame-retardant fiber-reinforced resin matrix composites, as detailed below: Add 30 wt% polymeric flame retardant (brominated SBS: M w =115596), 8 wt% low molecular weight flame retardant (dimethyl methylphosphonate: M r =124.08) and 2 wt% ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) were dissolved in 60 wt% organic solvent (dimethylacetamide). The electrospinning environment temperature (26℃), humidity (30%), and spinning voltage (60 kV) were adjusted, and carbon fiber fabric was adhered to the collection substrate, directly forming a nanofiber flame-retardant layer on the fabric surface. Fourteen layers of carbon fiber fabric coated with nanofiber flame retardant were laminated, and epoxy resin was infused through vacuum infusion. After curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate was obtained.
[0074] Example 7 By adjusting the electrospinning winding speed to 30 mm / min, a nanofiber flame-retardant layer of approximately 60 μm thickness is directly formed on the surface of the reinforcing fiber fabric; after curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate of 3.04 mm thickness is obtained.
[0075] Example 8 By adjusting the electrospinning winding speed to 40 mm / min, a nanofiber flame-retardant layer of approximately 40 μm thickness is directly formed on the surface of the reinforcing fiber fabric; after curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate of 3.03 mm thickness is obtained.
[0076] Example 9 By adjusting the electrospinning winding speed to 50 mm / min, a nanofiber flame-retardant layer of approximately 20 μm thickness is directly formed on the surface of the reinforcing fiber fabric; after curing, a flame-retardant carbon fiber reinforced epoxy resin matrix composite laminate of 3.01 mm thickness is obtained.
[0077] In Examples 7-9, the mass fractions of the nanofiber flame retardant layer, carbon fiber, and epoxy resin are shown in Table 5.
[0078] The flame-retardant carbon fiber reinforced epoxy resin matrix composite laminates prepared in Examples 7-9 were engraved into standard test strips according to ASTM and GB / T standard dimensions, and their properties were tested as follows. The results are shown in Table 6.
[0079] Table 5 Table 6 Comparative Example 1 This comparative example references the technical solution of patent CN116198144 A: using phenoxy resin as a thermoplastic polymer, adding 40 wt% pentaerythritol phosphate as a flame retardant, preparing a spinning solution, and then forming a flame-retardant nanofiber film on the surface of carbon fiber fabric by electrospinning. Then, the fiber fabric with the flame-retardant nanofiber film is stacked and cured by hot pressing molding process to obtain fiber-reinforced resin matrix composite material.
[0080] In Comparative Example 1, the flame-retardant fiber membrane had a mass fraction of only 3.81 wt%. The limiting oxygen index of this comparative example composite material was only 24.1%, and the UL94 vertical flammability rating was V-2, which is significantly lower than that of the embodiments of the present invention.
[0081] In Comparative Example 1, the flame-retardant nanofibers consist of a large amount of thermoplastic polymer (phenoxy resin) as the fiber body, with the flame retardant only dispersed as an additive rather than a pure flame retardant component. Its total proportion in the composite material is extremely low (<5 wt%), resulting in limited flame-retardant efficiency. This comparative example uses hot pressing, leading to a high porosity (approximately 3.5%) in the composite material, making it unsuitable for vacuum infusion processes and difficult to achieve integrated low-porosity molding of large, complex structural components. Furthermore, its spinnability and fiber morphology stability strongly depend on a specific polymer / flame retardant ratio, exhibiting poor versatility. Additionally, in this comparative example, the flame retardant is only physically dispersed and its content is limited, easily leading to significant agglomeration and uneven distribution in the film layer and the overall composite material, resulting in low flame-retardant efficiency and unstable effects. In contrast, the embodiments of this invention use nanofibers with a full flame retardant composition (without a polymer substrate), not only maximizing the flame retardant content but also achieving excellent flame-retardant performance and uniform flame retardant distribution without deteriorating the original mechanical properties through a structural design that intercalates between composite material layers.
[0082] Comparative Example 2 Add 25 wt% polymeric flame retardant (brominated SBS: M w =115596), 25 wt% low molecular weight flame retardant (ammonium polyphosphate: M r=1490) and 2 wt% ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) were dissolved in 48 wt% organic solvent (dimethylformamide). The electrospinning environment temperature (26℃), humidity (30%), spinning voltage (60 kV) and winding speed (40 mm / min) were adjusted.
[0083] Comparative Example 2 showed poor spinning performance, failing to form a stable nanofiber membrane. The fundamental reason was the excessively high content of low-molecular-weight flame retardant. The large amount of low-molecular-weight incorporation severely damaged the molecular chain entanglement and structural integrity of the high-molecular-weight flame retardant (brominated SBS), resulting in unstable spinning. This comparative example demonstrates that the precise design of the low-molecular-weight flame retardant content in this invention is crucial for achieving good spinnability.
[0084] Comparative Example 3 Add 30 wt% polymeric flame retardant (brominated SBS: M w =115596) and 10 wt% low molecular weight flame retardant (dimethyl methylphosphonate: M r =124.08) was dissolved in 60 wt% organic solvent (dimethylacetamide). The electrospinning environment temperature (26℃), humidity (30%), spinning voltage (60 kV) and winding speed (40 mm / min) were adjusted.
[0085] Comparative Example 3 showed poor conductivity of the spinning solution, severe jet breakage, and inability to form continuous nanofibers, resulting in extremely poor spinnability. This comparative example verifies the necessity of ionic liquids for improving spinnability.
[0086] Comparative Example 4 Compared with Example 1, in this comparative example, the high molecular weight flame retardant used is brominated SBS with a weight average molecular weight of 115,596, and the low molecular weight flame retardant used is ammonium polyphosphate with a molecular weight of 2,980. The molecular weight ratio of the two is less than 50, and the rest is the same as in Example 1.
[0087] The weight fractions of each component and the test results of the composite material specimens in Comparative Example 4 are shown in Tables 7 and 8, respectively. The SEM images of the prepared nanofiber flame retardant are shown below. Figure 2 As shown.
[0088] The results show that, in this comparative example, due to the molecular weight difference of less than 1.7 orders of magnitude (50), the low molecular weight components could not be effectively coated by the polymer chain network, resulting in rough fiber surfaces, uneven diameters, and inferior flame retardant distribution uniformity and flame retardant efficiency compared to Example 1.
[0089] Table 7 Table 8 The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A flame-retardant fiber-reinforced resin-based composite material, characterized in that, It includes a composite material layer made of reinforcing fiber fabric and resin, and a nanofiber flame retardant layer intercalated between the composite material layers. Each nanofiber flame retardant layer is composed of several nanofiber flame retardants arranged randomly, and the nanofiber flame retardants are composed of a polymer flame retardant, a low-molecular-weight flame retardant and an ionic liquid. The high molecular weight flame retardant is any one of brominated SBS, brominated PS, and brominated pentabromobenzyl polyacrylate; the low molecular weight flame retardant is any one or more of ammonium polyphosphate, resorcinol bis(diphenyl phosphate), pentaerythritol phosphate, dimethyl methylphosphonate, and triphenyl phosphate; and the ionic liquid contains phosphorus and / or bromine flame retardant elements.
2. The flame-retardant fiber-reinforced resin matrix composite material according to claim 1, characterized in that, The flame-retardant fiber-reinforced resin matrix composite material has a porosity of 0.5–1.5%, a thickness of 2–4 mm, and an interlaminar shear strength of 60–90 MPa; the nanofiber flame retardant layer has a thickness of 10–120 μm, a porosity of 50–95%, and an areal density of 3–20 g / m³. 2 The diameter of the nanofiber flame retardant is 100~600 nm.
3. The flame-retardant fiber-reinforced resin matrix composite material according to claim 1, characterized in that, Components including the following mass fractions: 30-40 wt% of resin 40-65 wt% of reinforcing fiber fabric Nanofiber flame retardant 5~20 wt%.
4. The flame-retardant fiber-reinforced resin-based composite material according to claim 1, characterized in that, The nanofiber-like flame retardant comprises the following components by mass fraction: 55-75 wt% of polymeric flame retardant; Low molecular weight flame retardant 20~40 wt% 3~10 wt% ionic liquid The weight-average molecular weight of the polymeric flame retardant is 50,000 to 150,000, the molecular weight of the low-molecular-weight flame retardant is 100 to 2,000, and the molecular weight ratio of the polymeric flame retardant to the low-molecular-weight flame retardant is ≥50.
5. The flame-retardant fiber-reinforced resin-based composite material according to claim 1, characterized in that, The resin is any one of epoxy resin, phenolic resin, isocyanate, vinyl resin, and unsaturated resin, and the resin viscosity is 100~2000 mPa·s; the reinforcing fiber fabric is any one of carbon fiber fabric, glass fiber fabric, aramid fiber fabric, and basalt fiber fabric; the ionic liquid is any one or more of tetrabutylphosphonium bromide, 1-ethyl-3-methylimidazolium diethyl phosphate, propyltributylphosphonium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylimidazolium bromide.
6. A method for preparing a flame-retardant fiber-reinforced resin matrix composite material as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Dissolve a high molecular weight flame retardant, a low molecular weight flame retardant, and an ionic liquid in an organic solvent to obtain a flame retardant electrospinning solution; S2: Using reinforced fiber fabric as the collection substrate, a nanofiber-like flame retardant layer is prepared on the surface of the reinforced fiber fabric through electrospinning process; S3: Lay up the reinforcing fiber fabric containing the nanofiber flame retardant layer, inject resin according to the mass ratio through a vacuum infusion process, and obtain the flame retardant fiber reinforced resin matrix composite material after curing.
7. The method for preparing the flame-retardant fiber-reinforced resin matrix composite material according to claim 6, characterized in that, In step S1, the content of the flame retardant electrospinning solution is 15-40 wt% of the polymeric flame retardant, 5-15 wt% of the low-molecular-weight flame retardant, 1-5 wt% of the ionic liquid, and 40-80 wt% of the organic solvent, wherein the organic solvent is any one or more of dimethylacetamide, dimethylformamide, methylpyrrolidone, toluene, and tetrahydrofuran.
8. The method for preparing the flame-retardant fiber-reinforced resin matrix composite material according to claim 6, characterized in that, In step S2, the process parameters of the electrospinning process include: an electrospinning ambient temperature of 20~28℃, a humidity of 20~40%, a spinning voltage of 20~60 kV, and a winding speed of 15~60 mm / min.
9. The method for preparing the flame-retardant fiber-reinforced resin matrix composite material according to claim 6, characterized in that, In step S3, the process parameters of the vacuum introduction process include: vacuum degree of -0.095 MPa to -0.100 MPa, and injection temperature of 5 to 100°C.
10. The application of a flame-retardant fiber-reinforced resin matrix composite material as described in any one of claims 1 to 5, characterized in that, The composite material is used to manufacture structural components in fields including aerospace, shipbuilding, wind power generation, and transportation materials technology.