A composite fiber material for concrete pipes, a fiber reinforcement cage and a method for producing the same

Abstract

The present application belongs to the technical field of fiber materials, and particularly relates to a composite fiber material for concrete pipes, a fiber reinforcement cage and a preparation method thereof. The composite fiber material for concrete pipes is composed of the following components in parts by mass: reinforcing fibers 40-55 parts, polyamide 6 30-45 parts, polyether type thermoplastic polyurethane 4-9 parts, maleic anhydride grafted compatibilizer 1.5-4 parts, aminopropyl triethoxysilane 0.4-1.2 parts, modified boron nitride 0.2-0.8 parts, hydrolysis-resistant agent 0.4-1.1 parts, and impact modifier 1-3 parts. The synergistic effect of the rigid reinforcement of the reinforcing fibers, the flexible toughening of the polyether type thermoplastic polyurethane and the impact modifier, the physical barrier of the modified boron nitride and the chemical hydrolysis resistance of the carbodiimide makes the composite fiber material have excellent impact toughness and long-term alkali aging resistance, and is suitable for the fiber reinforcement cage for concrete pipes.

Description

Technical Field

[0001] This invention belongs to the field of fiber material technology, specifically relating to a composite fiber material for concrete pipes, fiber reinforcement cages, and their preparation methods. Background Technology

[0002] Concrete pipes are widely used in water supply and drainage projects, urban underground pipelines, and other fields due to their advantages such as high rigidity, low cost, ease of manufacturing, and convenient installation. Currently, concrete pipes mainly include ordinary concrete pipes, reinforced concrete pipes, and prestressed steel cylinder concrete pipes.

[0003] In traditional reinforced concrete pipes, steel cages are typically used as the reinforcing framework. However, steel bars are highly susceptible to corrosion during long-term service. When cracks appear in the concrete, water and corrosive ions from the transported media or the environment seep into the pipe body through these cracks, causing the steel bars to corrode. Steel bar corrosion not only reduces its own strength but also causes the concrete to crack due to the expansion of corrosion products, further exacerbating structural damage. To address the problem of steel bar corrosion, the industry has successively proposed using fiberglass reinforced plastic (FRP) bars and resin-based fiber reinforced plastic (SRP) bars to replace steel bars in the preparation of steel cages for internal reinforcement of concrete pipes.

[0004] Chinese patent application CN105332095A discloses a method for preparing glass fiber composite materials. The application first involves blending mineral powder and silane additives, then melting and drawing the mixture to prepare glass fibers. Next, nylon resin and PS resin are blended and spun to obtain polymer fibers. Finally, the glass fibers and polymer fibers are woven together. However, this technical solution has several drawbacks that make it difficult to adapt to concrete pipes: the matrix resin uses a blend of nylon and PS resins. PS resin has extremely low polarity and poor compatibility with nylon, easily creating micropores at the interface between the two phases. Underground damp alkaline media can quickly penetrate the material along these interface pores, accelerating the hydrolytic aging of the nylon matrix, resulting in a significant decrease in mechanical strength after long-term alkaline immersion. Simultaneously, the high glass fiber content of this formulation makes the material significantly brittle, prone to crack propagation and reinforcement cage fracture failure under geological extrusion and ground load impact. Summary of the Invention

[0005] Existing composite fiber materials suffer from insufficient toughness and poor long-term alkali resistance. To address this issue, this invention provides a composite fiber material for concrete pipes, a fiber reinforcement cage, and a method for preparing the same.

[0006] To achieve the objectives of this invention, the following technical solution is adopted:

[0007] In a first aspect, the present invention provides a composite fiber material for concrete pipes, comprising the following components in parts by weight: 40-55 parts reinforcing fiber, 30-45 parts polyamide 6, 4-9 parts polyether thermoplastic polyurethane, 1.5-4 parts maleic anhydride graft compatibilizer, 0.4-1.2 parts aminopropyltriethoxysilane, 0.2-0.8 parts modified boron nitride, 0.4-1.1 parts anti-hydrolysis agent, and 1-3 parts impact modifier.

[0008] By adopting the above technical solutions, the enhanced fiber provides the main mechanical strength of the matrix; polyamide 6, as the matrix resin, provides good mechanical properties and heat resistance; the introduction of polyether-type thermoplastic polyurethane can significantly improve the flexibility and impact resistance of the composite fiber material; the anhydride groups in the maleic anhydride graft compatibilizer can react with the terminal amino groups of polyamide 6, while its polyolefin segments have good affinity with thermoplastic polyurethane, thereby effectively improving the interfacial compatibility between polyamide 6 and thermoplastic polyurethane; aminopropyltriethoxysilane, as a coupling agent, has amino functional groups that can react with the active groups on the modified boron nitride surface. The modified boron nitride is bonded to the polymer matrix by a silane group, while the other end of the silane is compatible with the polymer matrix, improving the dispersion uniformity and interfacial bonding of the modified boron nitride in the polymer matrix. The addition of modified boron nitride can also inhibit the penetration of alkali and water molecules from inside the concrete into the matrix. The addition of anti-hydrolysis agent can effectively inhibit the hydrolytic degradation of polyamide 6 and polyether thermoplastic polyurethane in humid environments, extending the service life of the material. The addition of impact modifier can further improve the impact toughness of the material. The entire formulation works synergistically to give the composite material excellent mechanical properties, alkali resistance and hydrolysis resistance, making it suitable for long-term underground burial of concrete pipes.

[0009] Furthermore, the preparation method of the modified boron nitride includes the following steps: Boron nitride, tannic acid, and water were mixed evenly, and the pH was adjusted to 7.2-7.8. The mixture was reacted at 50-55℃ for 5-6 hours. Then, ethylenediamine and 37wt% formaldehyde aqueous solution were added, the pH was adjusted to 6.0-6.5, and the mixture was reacted at 60-65℃ for 6-7 hours. The mixture was then centrifuged, washed, and dried to obtain modified boron nitride.

[0010] By employing the above-mentioned technical solution and using a one-pot method, boron nitride is pre-modified by adsorption onto the surface of boron nitride sheets via hydrogen bonding and π-π interactions of tannic acid. Subsequently, ethylenediamine and formaldehyde are added. Under weakly acidic conditions, the active hydrogen on the phenolic ring of tannic acid reacts with formaldehyde and ethylenediamine, grafting free primary amino groups onto the surface of boron nitride. This method features mild reaction conditions, simple operation, preserves the plate-like morphology of boron nitride, and ensures the functionalization of amino groups on the surface of boron nitride. The amino groups grafted onto the modified boron nitride surface can react with the alkoxy groups of aminopropyltriethoxysilane or the active groups of the polymer matrix, improving the dispersibility and interfacial bonding of boron nitride in the polymer matrix.

[0011] Furthermore, the mass ratio of boron nitride, tannic acid, and water is 1:(0.1~0.2):(200~300).

[0012] By adopting the above technical solution, it is possible to ensure that tannic acid is fully adsorbed on the surface of boron nitride, while avoiding agglomeration due to excessive tannic acid; the water phase ratio can ensure good dispersion of boron nitride in the system and improve the uniformity of the reaction.

[0013] Furthermore, the mass ratio of tannic acid, ethylenediamine, and 37wt% formaldehyde aqueous solution is 1:(0.5~0.7):(0.4~0.6).

[0014] By adopting the above technical solution, the feed ratio of reactants is controlled, formaldehyde provides methylene bridging units, and ethylenediamine is added in appropriate excess to ensure that the surface of the product is exposed to free primary amino groups; at the same time, excessive cross-linking between molecules is inhibited to prevent the modified boron nitride powder from agglomerating and ensuring its good dispersion in the polyamide 6 matrix.

[0015] Furthermore, the reinforcing fiber is glass fiber or basalt fiber.

[0016] By adopting the above technical solutions, glass fiber has the advantages of high strength and low cost, and can effectively improve the tensile strength and modulus of composite fiber materials; basalt fiber has excellent alkali resistance, high temperature resistance and corrosion resistance, and can maintain a long-term stable reinforcing effect in the alkaline environment of concrete pipes. Both fibers can be woven with polymer fibers to form a synergistically reinforcing network structure.

[0017] Furthermore, the modified boron nitride's D 50 The size is 3~8μm.

[0018] By adopting the above technical solution, this particle size range can maintain the two-dimensional plate-like labyrinth barrier effect of boron nitride, which hinders the diffusion and penetration of alkali ions and water molecules; it will not cause stress defect points to form inside the composite material due to excessively large particle size, nor will it cause agglomeration in extrusion processing due to excessively small particle size, thus taking into account both barrier performance and mechanical properties.

[0019] Furthermore, the anti-hydrolysis agent is carbodiimide.

[0020] By adopting the above technical solution, carbodiimide can capture the carboxyl end groups generated by the hydrolysis of polyamide 6, block the chain hydrolysis reaction of polyamide 6, inhibit the degradation of matrix molecular chains, and improve the long-term stability and durability of composite materials in humid environments and alkaline concrete media.

[0021] Furthermore, the impact modifier is acrylate core-shell rubber particles.

[0022] By adopting the above technical solution, the acrylate core-shell rubber particles possess a unique core-shell structure. The rubber core layer effectively absorbs and disperses impact energy, while the shell layer exhibits good compatibility with the polyamide 6 matrix. This impact modifier can improve the impact toughness of composite fiber materials while maintaining material rigidity and heat resistance.

[0023] Secondly, the present invention provides a method for preparing the above-mentioned composite fiber material for concrete pipes, comprising the following steps: Polyamide 6, polyether-type thermoplastic polyurethane, maleic anhydride graft compatibilizer, aminopropyltriethoxysilane, modified boron nitride, anti-hydrolysis agent and impact modifier are mixed evenly and spun to form polymer fibers. The reinforcing fibers and polymer fibers are then mixed and woven together to obtain composite fiber material for concrete pipes.

[0024] By adopting the above technical solution, the functional components of the matrix are first fully blended and then spun, and the functional fillers are evenly dispersed inside the polymer fiber; then, they are woven and compounded with the reinforcing fiber to achieve a tight bond between the reinforcing fiber and the modified polymer, forming a synergistic reinforcing structure.

[0025] Thirdly, the present invention provides a fiber reinforcement cage for concrete pipes, wherein the fiber reinforcement cage is formed by processing the above-mentioned composite fiber material for concrete pipes; the fiber reinforcement cage is a cylindrical mesh skeleton structure.

[0026] By adopting the above technical solution, this fiber-reinforced cage uses reinforcing fibers as the main load-bearing skeleton, providing excellent mechanical properties. Polymer fibers effectively connect the reinforcing fibers, ensuring the integrity and structural stability of the cage. Compared with traditional steel cages, this fiber-reinforced cage has the advantages of being lightweight, corrosion-resistant, and rust-free, effectively preventing concrete pipe cracking caused by steel corrosion. Simultaneously, the cylindrical mesh skeleton structure distributes stress evenly, and when pre-embedded inside the concrete pipe, it effectively distributes the stress generated by external and internal pressures on the pipe, improving the overall strength and crack resistance of the concrete pipe, making it suitable for use in concrete pipes.

[0027] In summary, the beneficial effects of this invention are: (1) The present invention adopts a composite system of reinforcing fiber rigidity enhancement, polyether thermoplastic polyurethane and acrylate core-shell particles for flexible toughening, which effectively solves the defects of high fiber filled polyamide materials being brittle and prone to cracking; at the same time, by forming covalent interface crosslinking between modified boron nitride amino and maleic anhydride compatibilizer, the interfacial bonding force between inorganic filler and organic matrix is ​​improved, internal defects are reduced, and the overall impact resistance of composite material is improved, meeting the long-term pressure bearing requirements of concrete pipelines; (2) This invention introduces a sheet-like modified boron nitride physical barrier structure and a carbodiimide chemical anti-hydrolysis system; the modified boron nitride forms a maze effect, effectively blocking external moisture and alkaline ions from penetrating into the material; the carbodiimide can capture the active end groups of the matrix hydrolysis, terminating the degradation chain reaction of polyamide 6, and the dual protection improves the long-term burial durability of the pipeline. (3) The preparation process of the composite fiber material for concrete pipes of the present invention is simple and can be continuously produced to obtain a composite fiber material with multiple functions of reinforcement and toughening. (4) The composite fiber reinforcement cage prepared by the present invention is a cylindrical mesh skeleton structure, which is uniformly stressed, has good integrity, and excellent bonding performance with concrete. It can effectively improve the overall deformation resistance of concrete pipes and the structure is safe and reliable. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments.

[0029] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples and comparative examples are commercially available.

[0030] Preparation Example 1 10g of flake boron nitride was dispersed in 2200g of deionized water and sonicated for 60min. 1.8g of tannic acid was added, and the pH was slowly adjusted to 7.5 with 0.5mol / L NaOH aqueous solution. The mixture was stirred in a water bath at 55℃ for 6h. 1.08g of ethylenediamine and 0.9g of 37wt% formaldehyde aqueous solution were added to the above system sequentially. The pH was slowly adjusted to 6.2 with 1mol / L hydrochloric acid aqueous solution. The mixture was heated to 60℃ and stirred for 6.5h. The precipitate was collected by centrifugation, washed three times with deionized water and twice with anhydrous ethanol, and dried under vacuum at 85℃ for 12h. The precipitate was then ground to obtain modified boron nitride.

[0031] Preparation Example 2 10g of flake boron nitride was dispersed in 2200g of deionized water and sonicated for 60min. 1.2g of tannic acid was added, and the pH was slowly adjusted to 7.4 with 0.5mol / L NaOH aqueous solution. The mixture was stirred in a water bath at 53℃ for 5.5h. 0.84g of ethylenediamine and 0.6g of 37wt% formaldehyde aqueous solution were added to the above system sequentially. The pH was slowly adjusted to 6.5 with 1mol / L hydrochloric acid aqueous solution. The mixture was heated to 60℃ and stirred for 7h. The precipitate was collected by centrifugation, washed three times with deionized water and twice with anhydrous ethanol, and dried under vacuum at 85℃ for 12h. The precipitate was then ground to obtain modified boron nitride.

[0032] Preparation Example 3 10g of flake boron nitride was dispersed in 2500g of deionized water and sonicated for 60min. 1.5g of tannic acid was added, and the pH was slowly adjusted to 7.3 with 0.5mol / L NaOH aqueous solution. The mixture was stirred in a water bath at 50℃ for 5.5h. 0.83g of ethylenediamine and 0.68g of 37wt% formaldehyde aqueous solution were added to the above system sequentially. The pH was slowly adjusted to 6.5 with 1mol / L hydrochloric acid aqueous solution. The mixture was heated to 65℃ and stirred for 6h. The precipitate was collected by centrifugation, washed three times with deionized water and twice with anhydrous ethanol, and dried under vacuum at 85℃ for 12h. The precipitate was then ground to obtain modified boron nitride.

[0033] Preparation Example 4 10g of flake boron nitride was dispersed in 2800g of deionized water and sonicated for 60min. 2g of tannic acid was added, and the pH was slowly adjusted to 7.6 with 0.5mol / L NaOH aqueous solution. The mixture was stirred in a water bath at 55℃ for 5h. 1.4g of ethylenediamine and 1.1g of 37wt% formaldehyde aqueous solution were added to the above system sequentially. The pH was slowly adjusted to 6.3 with 1mol / L hydrochloric acid aqueous solution. The mixture was heated to 62℃ and stirred for 7h. The precipitate was collected by centrifugation, washed three times with deionized water and twice with anhydrous ethanol, and dried under vacuum at 85℃ for 12h. The precipitate was then ground to obtain modified boron nitride.

[0034] Preparation Example 5 10g of flake boron nitride was dispersed in 2600g of deionized water and sonicated for 60min. 1.6g of tannic acid was added, and the pH was slowly adjusted to 7.2 with 0.5mol / L NaOH aqueous solution. The mixture was stirred in a water bath at 55℃ for 5.5h. 0.8g of ethylenediamine and 0.8g of 37wt% formaldehyde aqueous solution were added to the above system sequentially. The pH was slowly adjusted to 6.0 with 1mol / L hydrochloric acid aqueous solution. The mixture was heated to 65℃ and stirred for 6.5h. The precipitate was collected by centrifugation, washed three times with deionized water and twice with anhydrous ethanol, and dried under vacuum at 85℃ for 12h. The precipitate was then ground to obtain modified boron nitride.

[0035] The above-mentioned modified boron nitride D 50 The size is 3~8μm.

[0036] Example 1 This embodiment of a composite fiber material for concrete pipes is composed of the following components in parts by weight: 45 parts reinforcing fiber, 40 parts polyamide, 6 parts polyether thermoplastic polyurethane, 3 parts maleic anhydride graft compatibilizer, 1.1 parts aminopropyltriethoxysilane, 0.8 parts modified boron nitride, 0.7 parts carbodiimide anti-hydrolysis agent, and 3 parts acrylate core-shell rubber particles. The reinforcing fiber is alkali-free glass fiber; The modified boron nitride is the modified boron nitride obtained in Preparation Example 1.

[0037] The specific steps of the preparation method of the composite fiber material for concrete pipes in this embodiment are as follows: Polyamide 6, polyether-type thermoplastic polyurethane, maleic anhydride graft compatibilizer, aminopropyltriethoxysilane, modified boron nitride, anti-hydrolysis agent and impact modifier are mixed evenly and spun to form polymer fibers. The reinforcing fibers and polymer fibers are mixed and woven to obtain composite fiber material for concrete pipes. Finally, a cylindrical mesh skeleton fiber cage is prepared by molding, winding and consolidation.

[0038] Example 2 This embodiment of a composite fiber material for concrete pipes is composed of the following components in parts by weight: 45 parts reinforcing fiber, 35 parts polyamide 6, 5 parts polyether thermoplastic polyurethane, 2 parts maleic anhydride graft compatibilizer, 1 part aminopropyltriethoxysilane, 0.4 parts modified boron nitride, 0.5 parts carbodiimide anti-hydrolysis agent, and 1.5 parts acrylate core-shell rubber particles. The reinforcing fiber is alkali-free glass fiber; The modified boron nitride is the modified boron nitride obtained in Preparation Example 1.

[0039] The preparation method of the composite fiber material for concrete pipes in this embodiment is the same as in Embodiment 1.

[0040] Example 3 This embodiment of a composite fiber material for concrete pipes is composed of the following components in parts by weight: 50 parts reinforcing fiber, 30 parts polyamide, 9 parts polyether thermoplastic polyurethane, 2 parts maleic anhydride graft compatibilizer, 0.8 parts aminopropyltriethoxysilane, 0.6 parts modified boron nitride, 0.8 parts carbodiimide anti-hydrolysis agent, and 1.5 parts acrylate core-shell rubber particles; The reinforcing fiber is alkali-free glass fiber; The modified boron nitride is the modified boron nitride obtained in Preparation Example 2.

[0041] The preparation method of the composite fiber material for concrete pipes in this embodiment is the same as in Embodiment 1.

[0042] Example 4 This embodiment of a composite fiber material for concrete pipes is composed of the following components in parts by weight: 52 parts reinforcing fiber, 41 parts polyamide, 8 parts polyether thermoplastic polyurethane, 4 parts maleic anhydride graft compatibilizer, 1.2 parts aminopropyltriethoxysilane, 0.5 parts modified boron nitride, 0.6 parts carbodiimide anti-hydrolysis agent, and 3 parts acrylate core-shell rubber particles. The reinforcing fiber is alkali-free glass fiber; The modified boron nitride is the modified boron nitride obtained in Preparation Example 2.

[0043] The preparation method of the composite fiber material for concrete pipes in this embodiment is the same as in Embodiment 1.

[0044] Example 5 This embodiment of a composite fiber material for concrete pipes is composed of the following components in parts by weight: 44 parts reinforcing fiber, 38 parts polyamide, 8 parts polyether thermoplastic polyurethane, 3.5 parts maleic anhydride graft compatibilizer, 0.9 parts aminopropyltriethoxysilane, 0.8 parts modified boron nitride, 0.6 parts carbodiimide anti-hydrolysis agent, and 2.5 parts acrylate core-shell rubber particles; The reinforcing fiber is basalt fiber; The modified boron nitride is the modified boron nitride obtained in Preparation Example 3.

[0045] The preparation method of the composite fiber material for concrete pipes in this embodiment is the same as in Embodiment 1.

[0046] Comparative Example 1 The difference from Example 1 is that no modified boron nitride was added in this comparative example, but everything else is the same as in Example 1.

[0047] Comparative Example 2 The difference from Example 1 is that unmodified boron nitride was used instead of modified boron nitride in this comparative example, while all other aspects are the same as in Example 1.

[0048] Comparative Example 3 The difference from Example 1 is that the specific steps of the preparation method of the modified boron nitride in this comparative example are as follows, while the rest are the same as in Example 1: 10g of flake boron nitride was dispersed in 2200g of deionized water and sonicated for 60min. 1.8g of tannic acid was added, and the pH was slowly adjusted to 7.5 with 0.5mol / L NaOH aqueous solution. The mixture was stirred in a water bath at 55℃ for 6h. After the reaction was completed, the mixture was centrifuged, washed three times with deionized water, and dried under vacuum at 85℃ for 12h to obtain modified boron nitride.

[0049] Comparative Example 4 The difference from Example 1 is that this comparative example does not contain polyether-type thermoplastic polyurethane or impact modifier; otherwise, it is the same as Example 1.

[0050] Related performance tests The composite fiber materials prepared in Examples 1-5 and Comparative Examples 1-4 were subjected to relevant performance tests, and the test results are shown in Table 1.

[0051] Table 1 Test Results

[0052] As shown in Table 1: Examples 1-5 of this invention employ modified boron nitride, combined with polyether-type thermoplastic polyurethane, acrylate core-shell rubber particles, and carbodiimide. The resulting material exhibits higher notched impact strength, and its strength retention rate after alkali immersion is significantly better than that of the comparative examples. The amino groups on the surface of the modified boron nitride form a covalent interface with the system compatibilizer, ensuring uniform filler dispersion. Simultaneously, the stacking of two-dimensional sheets forms a labyrinth barrier, inhibiting the inward penetration of alkali ions and water molecules. Carbodiimide captures hydrolyzed end groups, blocking matrix degradation. These multiple mechanisms synergistically enhance durability.

[0053] Comparative Example 1 did not add modified boron nitride. The system lacked an inorganic lamellar barrier phase and interface reinforcement components, making it easy for alkaline media to penetrate the matrix and reducing its alkali resistance.

[0054] Comparative Example 2 uses unmodified boron nitride. The surface of boron nitride is inert, and the interface bonding with the polyamide 6 matrix is ​​weak. The filler agglomerates and forms internal defects, resulting in a simultaneous deterioration of impact toughness and alkali resistance.

[0055] Comparative Example 3 only achieved physical coating of tannic acid. The tannic acid was adsorbed onto the boron nitride surface by weak forces. Under alkaline immersion conditions, the coating layer was easy to fall off, and the filler interface enhancement and barrier effect were weakened.

[0056] Comparative Example 4, by removing polyether-type thermoplastic polyurethane and acrylate core-shell rubber particles, resulted in a system lacking a flexible toughening phase. The rigid filling with glass fiber led to extreme brittleness and low impact strength. Simultaneously, the absence of a polyether phase to assist in blocking media penetration resulted in a simultaneous decrease in the strength retention rate after alkali immersion.

[0057] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A composite fiber material for concrete pipes, characterized in that, It consists of the following components in parts by mass: 40-55 parts reinforcing fiber, 30-45 parts polyamide 6, 4-9 parts polyether thermoplastic polyurethane, 1.5-4 parts maleic anhydride graft compatibilizer, 0.4-1.2 parts aminopropyltriethoxysilane, 0.2-0.8 parts modified boron nitride, 0.4-1.1 parts anti-hydrolysis agent, and 1-3 parts impact modifier.

2. The composite fiber material for concrete pipes according to claim 1, characterized in that, The method for preparing the modified boron nitride includes the following steps: Boron nitride, tannic acid, and water were mixed evenly, and the pH was adjusted to 7.2-7.

8. The mixture was reacted at 50-55℃ for 5-6 hours. Then, ethylenediamine and 37wt% formaldehyde aqueous solution were added, the pH was adjusted to 6.0-6.5, and the mixture was reacted at 60-65℃ for 6-7 hours. The mixture was then centrifuged, washed, and dried to obtain modified boron nitride.

3. The composite fiber material for concrete pipes according to claim 2, characterized in that, The mass ratio of boron nitride, tannic acid and water is 1:(0.1~0.2):(200~300).

4. The composite fiber material for concrete pipes according to claim 2, characterized in that, The mass ratio of tannic acid, ethylenediamine, and 37wt% formaldehyde aqueous solution is 1:(0.5~0.7):(0.4~0.6).

5. The composite fiber material for concrete pipes according to claim 1, characterized in that, The reinforcing fiber is glass fiber or basalt fiber.

6. The composite fiber material for concrete pipes according to claim 1, characterized in that, The modified boron nitride D 50 The size is 3~8μm.

7. The composite fiber material for concrete pipes according to claim 1, characterized in that, The anti-hydrolysis agent is carbodiimide.

8. The composite fiber material for concrete pipes according to claim 1, characterized in that, The impact modifier is acrylate core-shell rubber particles.

9. A method for preparing a composite fiber material for concrete pipes according to any one of claims 1 to 8, characterized in that, Includes the following steps: Polyamide 6, polyether-type thermoplastic polyurethane, maleic anhydride graft compatibilizer, aminopropyltriethoxysilane, modified boron nitride, anti-hydrolysis agent and impact modifier are mixed evenly and spun to form polymer fibers. The reinforcing fibers and polymer fibers are then mixed and woven together to obtain composite fiber material for concrete pipes.

10. A fiber-reinforced cage for concrete pipes, characterized in that, The fiber reinforcement cage is formed by processing the composite fiber material for concrete pipes as described in claim 1; the fiber reinforcement cage is a cylindrical mesh skeleton structure.

Images