A high interlaminar shear strength continuous fiber-reinforced thermoplastic composite material and a method of making the same

Abstract

The application belongs to the field of polymer composites and molding technology, and particularly relates to a high interlaminar shear strength continuous fiber reinforced thermoplastic composite material and a preparation method thereof. The preparation method is as follows: a shear-resistant film is prepared by processing a thermoplastic elastomer; a plurality of layers of continuous fiber reinforced thermoplastic unidirectional tapes are stacked; the plurality of layers of shear-resistant films are inserted between the plurality of layers of continuous fiber reinforced thermoplastic unidirectional tapes and stacked to obtain a stacked assembly; and the stacked assembly is hot-pressed to form a product, which is then cooled, trimmed and cut. The shear-resistant film prepared independently is inserted to toughen the product, the elastomer does not interfere with the fiber impregnation process, the interlaminar stiffness is ensured by means of the hole fusion structure, the interlaminar shear strength and the in-plane mechanical properties of the composite material can be simultaneously improved, the preparation process is simple, and the composite material can be widely applied to the manufacturing field of automobile, rail transit, low-altitude aircraft and other parts.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials and molding technology, specifically relating to a high-strength interlayer shear strength continuous fiber reinforced thermoplastic composite material and its preparation method. Background Technology

[0002] Continuous fiber-reinforced thermoplastic unidirectional prepreg tapes, prepared by layup and hot pressing, exhibit extremely high strength within the plane of fiber extension. However, in the Z-direction perpendicular to the fiber plane, the lack of fiber reinforcement results in very low interlaminar shear strength, making the unidirectional tapes prone to interlaminar damage or separation under external impact loads. Currently, common methods to improve Z-direction shear strength include stitching, Z-pinning, toughening the unidirectional tape resin matrix, and toughening intercalation. However, stitching and Z-pinning methods cause some damage to the internal fibers, and adding toughening components to the unidirectional tape resin matrix often significantly hinders fiber impregnation.

[0003] Publication number CN102909905A discloses a continuous fiber-reinforced interlayer shear liquid crystal polymer composite material. This method involves uniformly dispersing a toughening agent into a liquid crystal polymer film while strictly controlling the melting point of the liquid crystal polymer film, followed by hot-pressing under inert gas protection. This method places stringent requirements on the formulation of the liquid crystal polymer resins in both the toughening and reinforcing layers, and the process of uniformly dispersing the toughening agent and liquid crystal polymer in the toughening layer is also quite challenging.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] To address the shortcomings of existing technologies, such as insufficient interlaminar shear strength in continuous fiber reinforced thermoplastic composites, the tendency of Z-axis reinforcement methods like stitching and Z-pinning to damage in-plane fibers and reduce in-plane mechanical properties, and the hindering of fiber impregnation and impact on the quality of unidirectional tape preparation through resin matrix toughening, while existing toughening intercalation schemes suffer from stringent resin formulation requirements, difficulties in component blending and dispersion, and challenges in simultaneously achieving both in-plane stiffness and interlaminar shear resistance, this invention provides a high-strength continuous fiber reinforced thermoplastic composite material that balances both mechanical strength and shear resistance. Its preparation method includes the following steps:

[0006] (1) A shear-resistant film is obtained by processing a thermoplastic elastomer; (2) Laying out multi-layer continuous fiber reinforced thermoplastic unidirectional tapes; (3) Insert the multilayer shear-resistant film between the multilayer continuous fiber-reinforced thermoplastic unidirectional tapes and stack them to obtain a laminated assembly; (4) The laminated assembly is hot-pressed, cooled, trimmed and cut to obtain the interlayer shear strength continuous fiber reinforced thermoplastic composite material.

[0007] Preferably, in step (1), the thermoplastic elastomer is processed by extrusion calendering, casting or blown film process to obtain a shear-resistant film; And / or, the thermoplastic elastomer is one or two of polyolefin thermoplastic elastomers (TPO), styrene thermoplastic elastomers (SEBS), and polyurethane thermoplastic elastomers (TPU); And / or, the thickness of the shear-resistant film is 50-200 μm.

[0008] Preferably, in step (1), the obtained shear-resistant film has pores; wherein: The shape of the hole is at least one of circular, elliptical, or slotted. The size of the hole is 0.10-1.0 mm, and the area of ​​the hole accounts for 5-50% of the total area of ​​the shear-resistant film.

[0009] Preferably, in step (2), the method for preparing the continuous fiber reinforced thermoplastic unidirectional tape is as follows: (2-1) Impregnate continuous fibers in molten thermoplastic resin to obtain impregnated continuous fibers; (2-2) The impregnated continuous fibers are calendered to obtain the continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.1-0.4 mm.

[0010] Preferably, the continuous fiber is one or a combination of two or more of carbon fiber, glass fiber, and aramid fiber; And / or, the thermoplastic resin is one or more of polyolefin, polyamide, and polyester.

[0011] Preferably, in step (2), the angle at which the continuous fiber reinforced thermoplastic unidirectional tapes are stacked includes at least four angles selected from 0°, ±15°, ±30°, ±45°, ±60°, ±75°, and 90°.

[0012] Preferably, in step (4), the laminated assembly is hot-pressed for 1-5 minutes at a temperature of 170-300℃ and a hot-pressing pressure of 0.1-4.0MPa. After completion, the laminated assembly is cooled to 50-100℃ for 1-2 minutes at a cooling pressure of 0.1-2.0MPa. Finally, it is trimmed and cut to obtain the interlayer shear strength continuous fiber reinforced thermoplastic composite material with a thickness of 1.0-10.0mm. The continuous fiber reinforced thermoplastic unidirectional tape and the shear-resistant film are fused together by hot pressing to form an integral structure, and adjacent continuous fiber reinforced thermoplastic unidirectional tapes are fused together through the pores on the shear-resistant film.

[0013] Based on the same technical concept, the present invention provides a high-strength interlayer shear strength continuous fiber reinforced thermoplastic composite material obtained by the above preparation method.

[0014] Preferably, the interlayer shear strength continuous fiber reinforced thermoplastic composite material comprises a continuous fiber reinforced thermoplastic unidirectional tape and a shear-resistant film; wherein: The continuous fiber-reinforced thermoplastic unidirectional tape and the shear-resistant film are arranged alternately in sequence; The shear-resistant film has pores.

[0015] Preferably, the ratio of the total thickness of the shear-resistant film to the total thickness of the continuous fiber-reinforced thermoplastic unidirectional tape is ≥0.10.

[0016] The beneficial effects of this invention are as follows: 1. The high-strength continuous fiber reinforced thermoplastic composite material of the present invention is obtained by hot pressing continuous fiber reinforced thermoplastic unidirectional tape and shear-resistant film after lamination. The shear-resistant film and continuous fiber reinforced thermoplastic unidirectional tape are prepared independently, avoiding the interference of thermoplastic elastomer on the fiber impregnation process of unidirectional tape. Therefore, the fiber content in continuous fiber reinforced thermoplastic unidirectional tape can be unlimited, making full use of the high strength characteristics of continuous fibers.

[0017] 2. The shear-resistant film of the present invention is prepared by extrusion calendering, casting or blown film process. The preparation process is simple and easy to implement. The proportion of each component in the shear-resistant film and the micromorphology of the thermoplastic elastomer can be adjusted independently, thereby maximizing the high toughness characteristics in the plane.

[0018] 3. In this invention, the shear-resistant film has small-sized pores. When the continuous fiber-reinforced thermoplastic unidirectional tape is hot-pressed after being stacked with the shear-resistant film, the resin matrix of two adjacent unidirectional tapes fuses together through the pores of the film, achieving a Z-pin-like effect. The resin of the unidirectional tape anchors the adjacent unidirectional tapes together through the pores, so that the interlaminar stiffness of the unidirectional tape is not reduced due to the toughening effect of the film layer. At the same time, due to the presence of the shear-resistant film, the interlaminar toughness and shear strength of the unidirectional tapes are greatly improved, thus exerting a synergistic effect and taking into account both the stiffness of the composite material and the interlaminar shear strength.

[0019] 4. The stacking angle and stacking sequence of the continuous fiber reinforced thermoplastic unidirectional tape in this invention enable the continuous fiber reinforced thermoplastic composite material with high interlayer shear strength to have excellent interlayer strength and mechanical strength, thereby providing material users with a variety of choices and design redundancy space.

[0020] 5. The high-strength inter-layer shear strength continuous fiber reinforced thermoplastic composite material of the present invention can be widely used in the manufacturing technology of automobiles, rail transit, low-altitude aircraft and other parts to meet the needs of different application scenarios. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a high-strength continuous fiber reinforced thermoplastic composite material with high inter-layer shear strength provided by the present invention.

[0023] Figure 2 This is a schematic diagram of the structure of intercalated continuous fiber-reinforced thermoplastic unidirectional tape and shear-resistant film.

[0024] The attached figures are labeled as follows: 1- Interlayer shear strength continuous fiber reinforced thermoplastic composite material; 2- Continuous fiber reinforced thermoplastic unidirectional tape; 3- Shear-resistant film; 4- Pores. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] This invention provides a method for preparing a high-strength, continuous-fiber-reinforced thermoplastic composite material with strong inter-layer shear strength. The preparation method includes the following steps: (1) A shear-resistant film is obtained by processing a thermoplastic elastomer; wherein: Thermoplastic elastomers are processed through extrusion calendering, casting, or blown film processes to obtain shear-resistant films; The thermoplastic elastomer is one or two of the following: polyolefin thermoplastic elastomers, styrene thermoplastic elastomers, and polyurethane thermoplastic elastomers. The thickness of the shear-resistant film is 50-200 μm; The obtained shear-resistant film has pores; the shape of the pores is at least one of circular, elliptical, or slotted; the size of the pores is 0.10-1.0 mm, and the area of ​​the pores accounts for 5-50% of the total area of ​​the shear-resistant film; (2) Laying multiple layers of continuous fiber-reinforced thermoplastic unidirectional tape; wherein: The method for preparing the continuous fiber reinforced thermoplastic unidirectional tape is as follows: (2-1) Impregnate continuous fibers in thermoplastic resin to obtain impregnated continuous fibers; (2-2) The impregnated continuous fibers are calendered to obtain a continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.1-0.4 mm; The continuous fiber is one or a combination of two or more of carbon fiber, glass fiber, and aramid fiber. The thermoplastic resin is one or more of polyolefin, polyamide, and polyester; The angles at which continuous fiber-reinforced thermoplastic unidirectional tapes are stacked include at least four of the following: 0°, ±15°, ±30°, ±45°, ±60°, ±75°, and 90°. (3) Insert the multilayer shear-resistant film between the multilayer continuous fiber-reinforced thermoplastic unidirectional tapes and stack them to obtain a laminated assembly; (4) The laminated assembly is hot-pressed, cooled, and trimmed to obtain the continuous fiber-reinforced thermoplastic composite material with high interlayer shear strength, wherein: The laminated assembly is hot-pressed for 1-5 minutes at a temperature of 170-300℃ and a hot-pressing pressure of 0.1-4.0MPa. After hot pressing, the laminated assembly is cooled to 50-100℃ for 1-2 minutes at a cooling pressure of 0.1-2.0MPa. Finally, it is trimmed and cut to obtain the interlayer shear strength continuous fiber reinforced thermoplastic composite material with a thickness of 1.0-10.0mm.

[0027] Example 1 This embodiment provides a method for preparing a continuous fiber-reinforced thermoplastic composite material with high interlayer shear strength, the preparation method comprising the following steps: (1) Ethylene-1-octene copolymer (polyolefin thermoplastic elastomer, POE) was blown into a film to obtain a porous shear-resistant film with a thickness of 75 μm. The holes were circular with a diameter of 0.25 mm, and the area of ​​the circular holes accounted for 10% of the film area. (2) Using continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.25 mm, the tapes are stacked sequentially at angles of 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°, so that the angles of the unidirectional tapes are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°; wherein, the preparation method of the continuous fiber reinforced thermoplastic unidirectional tape is as follows: (2-1) Impregnate carbon fibers in molten polypropylene resin (thermoplastic resin) to obtain impregnated continuous fibers; (2-2) The impregnated continuous fibers are calendered to obtain a continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.25 mm; (3) Insert a shear-resistant film between each layer of continuous fiber-reinforced thermoplastic unidirectional tape to form a laminated assembly of alternating unidirectional tape and shear-resistant film, wherein the layup angles of the unidirectional tape are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0° respectively. (4) The laminated assembly is hot-pressed for 3 minutes at a temperature of 170°C and a hot-pressing pressure of 0.2 MPa. After completion, the laminated assembly is cooled to 50°C for 2 minutes at a cooling pressure of 0.1 MPa. Finally, it is trimmed and cut to obtain the interlayer shear strength continuous fiber reinforced thermoplastic composite material with a thickness of 2.85 mm.

[0028] Example 2 This embodiment provides a method for preparing a continuous fiber-reinforced thermoplastic composite material with high interlayer shear strength, the preparation method comprising the following steps: (1) Ethylene-1-octene copolymer (polyolefin thermoplastic elastomer, POE) was blown into a film to obtain a porous shear-resistant film with a thickness of 75 μm. The holes were circular with a diameter of 0.50 mm, and the area of ​​the circular holes accounted for 10% of the film area. (2) Using continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.25 mm, the tapes are stacked sequentially at angles of 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°, so that the angles of the unidirectional tapes are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°; wherein, the preparation method of the continuous fiber reinforced thermoplastic unidirectional tape is as follows: (2-1) Impregnate carbon fibers in molten polypropylene resin (thermoplastic resin) to obtain impregnated continuous fibers; (2-2) The impregnated continuous fibers are calendered to obtain a continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.25 mm; (3) Insert a shear-resistant film between each layer of continuous fiber-reinforced thermoplastic unidirectional tape to form a laminated assembly of alternating unidirectional tape and shear-resistant film, wherein the layup angles of the unidirectional tape are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0° respectively. (4) The laminated assembly is hot-pressed for 3 minutes at a temperature of 170°C and a hot-pressing pressure of 0.2 MPa. After completion, the laminated assembly is cooled to 50°C for 2 minutes at a cooling pressure of 0.1 MPa. Finally, it is trimmed and cut to obtain the interlayer shear strength continuous fiber reinforced thermoplastic composite material with a thickness of 2.85 mm.

[0029] Example 3 This embodiment provides a method for preparing a continuous fiber-reinforced thermoplastic composite material with high interlayer shear strength, the preparation method comprising the following steps: (1) Ethylene-1-octene copolymer (polyolefin thermoplastic elastomer, POE) was blown into a film to obtain a porous shear-resistant film with a thickness of 75 μm. The holes were circular with a diameter of 0.75 mm, and the area of ​​the circular holes accounted for 10% of the film area. (2) Using continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.25 mm, the tapes are stacked sequentially at angles of 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°, so that the angles of the unidirectional tapes are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°; wherein, the preparation method of the continuous fiber reinforced thermoplastic unidirectional tape is as follows: (2-1) Impregnate carbon fibers in molten polypropylene resin (thermoplastic resin) to obtain impregnated continuous fibers; (2-2) The impregnated continuous fibers are calendered to obtain a continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.25 mm; (3) Insert a shear-resistant film between each layer of continuous fiber-reinforced thermoplastic unidirectional tape to form a laminated assembly of alternating unidirectional tape and shear-resistant film, wherein the layup angles of the unidirectional tape are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0° respectively. (4) The laminated assembly is hot-pressed for 3 minutes at a temperature of 170°C and a hot-pressing pressure of 0.2 MPa. After completion, the laminated assembly is cooled to 50°C for 2 minutes at a cooling pressure of 0.1 MPa. Finally, it is trimmed and cut to obtain the interlayer shear strength continuous fiber reinforced thermoplastic composite material with a thickness of 2.85 mm.

[0030] Example 4 This embodiment provides a method for preparing a continuous fiber-reinforced thermoplastic composite material with high interlayer shear strength, the preparation method comprising the following steps: (1) Ethylene-1-octene copolymer (polyolefin thermoplastic elastomer, POE) was blown into a film to obtain a porous shear-resistant film with a thickness of 75 μm. The holes were circular with a diameter of 0.50 mm, and the area of ​​the circular holes accounted for 20% of the film area. (2) Using continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.25 mm, the tapes are stacked sequentially at angles of 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°, so that the angles of the unidirectional tapes are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°; wherein, the preparation method of the continuous fiber reinforced thermoplastic unidirectional tape is as follows: (2-1) Impregnate carbon fibers in molten polypropylene resin (thermoplastic resin) to obtain impregnated continuous fibers; (2-2) The impregnated continuous fibers are calendered to obtain a continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.25 mm; (3) Insert a shear-resistant film between each layer of continuous fiber-reinforced thermoplastic unidirectional tape to form a laminated assembly of alternating unidirectional tape and shear-resistant film, wherein the layup angles of the unidirectional tape are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0° respectively. (4) The laminated assembly is hot-pressed for 3 minutes at a temperature of 170°C and a hot-pressing pressure of 0.2 MPa. After completion, the laminated assembly is cooled to 50°C for 2 minutes at a cooling pressure of 0.1 MPa. Finally, it is trimmed and cut to obtain the interlayer shear strength continuous fiber reinforced thermoplastic composite material with a thickness of 2.85 mm.

[0031] Example 5 This embodiment provides a method for preparing a continuous fiber-reinforced thermoplastic composite material with high interlayer shear strength, the preparation method comprising the following steps: (1) Ethylene-1-octene copolymer (polyolefin thermoplastic elastomer, POE) was blown into a film to obtain a porous shear-resistant film with a thickness of 75 μm. The holes were circular with a diameter of 0.50 mm, and the area of ​​the circular holes accounted for 40% of the film area. (2) Using continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.25 mm, the tapes are stacked sequentially at angles of 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°, so that the angles of the unidirectional tapes are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°; wherein, the preparation method of the continuous fiber reinforced thermoplastic unidirectional tape is as follows: (2-1) Impregnate carbon fibers in molten polypropylene resin (thermoplastic resin) to obtain impregnated continuous fibers; (2-2) The impregnated continuous fibers are calendered to obtain a continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.25 mm; (3) Insert a shear-resistant film between each layer of continuous fiber-reinforced thermoplastic unidirectional tape to form a laminated assembly of alternating unidirectional tape and shear-resistant film, wherein the layup angles of the unidirectional tape are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0° respectively. (4) The laminated assembly is hot-pressed for 3 minutes at a temperature of 170°C and a hot-pressing pressure of 0.2 MPa. After completion, the laminated assembly is cooled to 50°C for 2 minutes at a cooling pressure of 0.1 MPa. Finally, it is trimmed and cut to obtain the interlayer shear strength continuous fiber reinforced thermoplastic composite material with a thickness of 2.85 mm.

[0032] Example 6 This embodiment provides a method for preparing a continuous fiber-reinforced thermoplastic composite material with high interlayer shear strength, the preparation method comprising the following steps: (1) Ethylene-1-octene copolymer (polyolefin thermoplastic elastomer, POE) was blown into a film to obtain a porous shear-resistant film with a thickness of 50 μm. The holes were circular with a diameter of 0.50 mm, and the area of ​​the circular holes accounted for 10% of the film area. (2) Using continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.3 mm, the tapes are stacked sequentially at angles of 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°, so that the angles of the unidirectional tapes are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0°; wherein, the preparation method of the continuous fiber reinforced thermoplastic unidirectional tape is as follows: (2-1) Impregnate carbon fibers in molten polypropylene resin (thermoplastic resin) to obtain impregnated continuous fibers; (2-2) The impregnated continuous fibers are calendered to obtain a continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.3 mm; (3) Insert a shear-resistant film between each layer of continuous fiber-reinforced thermoplastic unidirectional tape to form a laminated assembly of alternating unidirectional tape and shear-resistant film, wherein the layup angles of the unidirectional tape are 0°, 30°, 45°, 60°, 90°, -60°, -45°, -30°, and 0° respectively. (4) The laminated assembly is hot-pressed for 3 minutes at a temperature of 170°C and a hot-pressing pressure of 0.2 MPa. After completion, the laminated assembly is cooled to 50°C for 2 minutes at a cooling pressure of 0.1 MPa. Finally, it is trimmed and cut to obtain the interlayer shear strength continuous fiber reinforced thermoplastic composite material with a thickness of 2.85 mm.

[0033] Example 7 refer to Figure 1 and Figure 2 This embodiment provides a high-strength interlayer shear strength continuous fiber reinforced thermoplastic composite material 1, which includes a continuous fiber reinforced thermoplastic unidirectional tape 2 and a shear-resistant film 3; wherein: The continuous fiber-reinforced thermoplastic unidirectional tape 2 and the shear-resistant film 3 are arranged alternately in sequence; The shear-resistant film 3 has holes 4.

[0034] Comparative Example 1 The difference between this comparative example and Example 1 is that the ethylene-1-octene copolymer (polyolefin thermoplastic elastomer) in Example 1 is replaced with polypropylene resin (bulk resin), while other operations are the same as in Example 1, and a continuous fiber reinforced thermoplastic composite material is finally obtained.

[0035] Comparative Example 2 The difference between this comparative example and Example 1 is that the POE elastomer film from Example 1 is mixed with polypropylene resin and melt-blended using a twin-screw extruder to ensure that the POE elastomer is uniformly distributed in the polypropylene melt. Then, it is impregnated and calendered with continuous fibers to obtain a continuous fiber-reinforced thermoplastic unidirectional tape containing the POE elastomer component. Other operations are the same as in Example 1 to obtain a continuous fiber-reinforced thermoplastic composite material with a uniform distribution of thermoplastic elastomer.

[0036] Comparative Example 3 The difference between this comparative example and Example 2 is that the POE elastomer film in Example 2 is mixed with polypropylene resin and melt-blended using a twin-screw extruder to make the POE elastomer uniformly distributed in the polypropylene melt. Then, it is impregnated and calendered with continuous fibers to obtain a continuous fiber reinforced thermoplastic unidirectional tape containing the POE elastomer component. Other operations are the same as in Example 2 to obtain a continuous fiber reinforced thermoplastic composite material with a uniform distribution of thermoplastic elastomer.

[0037] Comparative Example 4 The difference between this comparative example and Example 3 is that the POE elastomer film in Example 3 is mixed with polypropylene resin and melt-blended using a twin-screw extruder to make the POE elastomer uniformly distributed in the polypropylene melt. Then, it is impregnated and calendered with continuous fibers to obtain a continuous fiber reinforced thermoplastic unidirectional tape containing the POE elastomer component. Other operations are the same as in Example 3 to obtain a continuous fiber reinforced thermoplastic composite material with a uniform distribution of thermoplastic elastomer.

[0038] Comparative Example 5 The difference between this comparative example and Example 1 is that in step (1), the shear-resistant film obtained does not contain pores, while other operations are consistent with Example 1.

[0039] Verification Example The composite materials obtained in Examples 1-6 and Comparative Examples 1-5 were tested, and the results are shown in Table 1.

[0040] Table 1

[0041] The data in Table 1 will be analyzed in detail below: (a) Impact of structural parameters on performance (comparison within the example group) 1. The effect of hole diameter on performance Comparing Examples 1-3 (with a fixed hole area ratio of 10% and diameters of 0.25mm, 0.50mm, and 0.75mm respectively), the results are as follows: (1-1) The interlaminar shear strength showed a trend of first increasing and then decreasing: it reached a peak of 47.2 MPa at a pore size of 0.50 mm, 45.7 MPa at 0.25 mm, and dropped back to 46.3 MPa at 0.75 mm. This indicates that there is an optimal pore size range: when the pore size is too small, the number and size of the "Z-direction anchor posts" formed by resin fusion are small, resulting in insufficient interlaminar stress transfer efficiency; when the pore size is too large, the continuous toughening region of the elastomer film is excessively segmented, and the interlaminar crack passivation effect is weakened.

[0042] (1-2) The Z-axis flexural strength and modulus continuously increase with the increase of pore size: the flexural strength increases from 328.7 MPa to 355.8 MPa, and the flexural modulus increases from 13.2 GPa to 16.8 GPa. The essence is that the larger the pore size, the higher the area of ​​direct fusion of adjacent unidirectional resins, and the closer the material is to the bulk stiffness level without intercalation.

[0043] In summary, it is demonstrated that the aperture diameter can be used as a parameter for adjusting the "stiffness-toughness". The small aperture scheme focuses on interlaminar shear toughness, while the large aperture scheme focuses on out-of-plane load-bearing stiffness, giving the material a wide range of adaptability.

[0044] 2. The impact of the proportion of void area on performance Comparing Examples 2, 4, and 5 (with a fixed aperture of 0.50 mm and area percentages of 10%, 20%, and 40%, respectively), the results are as follows: (2-1) Bending strength and modulus increase approximately linearly with increasing proportion: Bending modulus increases from 14.1 GPa to 18.4 GPa, of which 18.4 GPa in Example 5 is almost the same as that in Comparative Example 1 (18.6 GPa) without elastomer intercalation, with a stiffness loss rate of only about 1.1%.

[0045] (2-2) The interlaminar shear strength also showed a trend of first rising and then falling: it reached the highest value of 48.2 MPa when the proportion was 20%, and fell slightly when the proportion was 40%, but still remained at a high level of 46.9 MPa.

[0046] In summary, it is demonstrated that when the area of ​​pores reaches 40%, the material can achieve an interlaminar shear strength increase of approximately 50.3% compared to the bulk without sacrificing interlaminar stiffness. This directly breaks through the technical prejudice in the field that "interlaminar toughening inevitably leads to a significant decrease in stiffness," and is one of the most core technical contributions of this invention.

[0047] (II) Comparison and verification with existing technical solutions (examples and comparative examples) 1. Comparison with blank baseline (Comparative Example 1: pure resin intercalation, without elastomer toughening) (1-1) Comparative Example 1 is a pure polypropylene film intercalation sample without toughening, representing the baseline performance of traditional continuous fiber reinforced thermoplastic composites: the interlaminar shear strength is only 31.2 MPa, which is the lowest in the group.

[0048] (1-2) The optimal toughening scheme of the present invention (Example 4): interlaminar shear strength is increased by 54.5%, while flexural modulus decreases by only about 10.2%; (1-3) The high stiffness solution of the present invention (Example 5): the interlaminar shear strength is increased by 50.3%, and the flexural modulus is only reduced by about 1.1%.

[0049] Both sets of data jointly demonstrate that the perforated elastic film intercalation and the hole fusion anchoring structure of the present invention solves the problem of "strength improvement often accompanied by stiffness loss" encountered in the traditional toughening process, and achieves synergistic optimization of the two.

[0050] 2. Comparison of toughening routes through blending with the matrix (Comparative Examples 2-4: Elastomers mixed into resin matrices) Comparative Examples 2-4 correspond to the total elastomer usage in Examples 1-3, using a conventional method in the art of "blending elastomer with resin and then impregnating fibers". The results show that: (2-1) The interlaminar shear strength is only 31.8-33.7 MPa, which is less than 9% higher than the baseline comparative example 1, and far lower than the level of 45 MPa or more in the embodiment of the present invention; (2-2) The core reason for its extremely low toughening efficiency is that the elastomer is uniformly dispersed in the resin matrix, with only a very small portion distributed on the crack propagation path at the interlayer interface, which cannot effectively prevent interlayer delamination; at the same time, the elastomer mixed into the matrix will also increase the melt viscosity and hinder fiber impregnation, which is consistent with the technical problems described in the background art.

[0051] (2-3) This comparison directly verifies the technical superiority of the present invention in that the elastomer is independently film-forming and precisely intercalated in the interlayer route—the toughening component is precisely arranged at the critical failure interface, the toughening efficiency is increased several times compared with the matrix blending, and the interference with the fiber impregnation process is completely avoided.

[0052] 3. Comparison with the non-porous elastic film intercalation route (Comparative Example 5: Non-porous elastomer film intercalation) Comparative Example 5 uses a pore-free pure POE thin film intercalation, and the results show: (3-1) The interlaminar shear strength reached 46.8 MPa, which is close to that of Example 1, proving that the intercalation of the elastomer film itself can indeed effectively improve the interlaminar toughness; (3-2) However, the Z-direction bending strength (311.6 MPa) and bending modulus (13.0 GPa) were the lowest in the group, significantly lower than all the examples with holes.

[0053] (3-3) This comparison shows that setting holes in elastic films is not a conventional technique in this field, but a targeted design to solve the specific technical problem of a sharp drop in stiffness caused by pure elastic intercalation. The resin fusion pillars formed by the holes have a pinning effect similar to Z-pins, directly transmitting interlaminar normal stress, greatly restoring interlaminar stiffness, and forming a synergistic effect with the toughening effect of the elastomer. The effect of this technique cannot be expected through conventional techniques.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a high-strength, continuous fiber-reinforced thermoplastic composite material with high interlayer shear strength, characterized in that, The preparation method includes the following steps: (1) A shear-resistant film is obtained by processing a thermoplastic elastomer; (2) Laying out multi-layer continuous fiber reinforced thermoplastic unidirectional tapes; (3) Insert the multilayer shear-resistant film between the multilayer continuous fiber-reinforced thermoplastic unidirectional tapes and stack them to obtain a laminated assembly; (4) The laminated assembly is hot-pressed, cooled, trimmed and cut to obtain the interlayer shear strength continuous fiber reinforced thermoplastic composite material.

2. The method for preparing the high-strength interlayer continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that, In step (1), the thermoplastic elastomer is processed by extrusion calendering, casting or blown film process to obtain a shear-resistant film; And / or, the thermoplastic elastomer is one or two of polyolefin thermoplastic elastomers, styrene thermoplastic elastomers, and polyurethane thermoplastic elastomers; And / or, the thickness of the shear-resistant film is 50-200 μm.

3. The method for preparing the interlayer shear strength continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that, In step (1), the obtained shear-resistant film has pores; wherein: The shape of the hole is at least one of circular, elliptical, or slotted. The size of the hole is 0.10-1.0 mm, and the area of ​​the hole accounts for 5-50% of the total area of ​​the shear-resistant film.

4. The method for preparing the high-strength interlayer continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that, In step (2), the method for preparing the continuous fiber reinforced thermoplastic unidirectional tape is as follows: (2-1) Impregnate continuous fibers in molten thermoplastic resin to obtain impregnated continuous fibers; (2-2) The impregnated continuous fibers are calendered to obtain the continuous fiber reinforced thermoplastic unidirectional tape with a thickness of 0.1-0.4 mm.

5. The method for preparing the interlayer shear strength continuous fiber reinforced thermoplastic composite material according to claim 4, characterized in that, The continuous fiber is one or a combination of two or more of carbon fiber, glass fiber, and aramid fiber. And / or, the thermoplastic resin is one or more of polyolefin, polyamide, and polyester.

6. The method for preparing the interlayer shear strength continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that, In step (2), the angle at which the continuous fiber reinforced thermoplastic unidirectional tapes are stacked includes at least four angles among 0°, ±15°, ±30°, ±45°, ±60°, ±75°, and 90°.

7. The method for preparing the high-strength interlayer continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that, In step (4), the laminated assembly is hot-pressed for 1-5 minutes at a temperature of 170-300℃ and a hot-pressing pressure of 0.1-4.0MPa. After completion, the laminated assembly is cooled to 50-100℃ for 1-2 minutes at a cooling pressure of 0.1-2.0MPa. Finally, it is trimmed and cut to obtain the interlayer shear strength continuous fiber reinforced thermoplastic composite material with a thickness of 1.0-10.0mm.

8. The high-strength continuous fiber-reinforced thermoplastic composite material with high interlayer shear strength obtained by the preparation method according to any one of claims 1-7.

9. The interlayer shear strength continuous fiber reinforced thermoplastic composite material according to claim 8, characterized in that, It comprises a continuous fiber-reinforced thermoplastic unidirectional tape and a shear-resistant film; wherein: The continuous fiber-reinforced thermoplastic unidirectional tape and the shear-resistant film are arranged alternately in sequence; The shear-resistant film has pores.

10. The interlayer shear strength continuous fiber reinforced thermoplastic composite material according to claim 9, characterized in that, The ratio of the total thickness of the shear-resistant film to the total thickness of the continuous fiber-reinforced thermoplastic unidirectional tape is ≥0.10.

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