Weather-resistant basalt fiber reinforced polyamide composite material, preparation method and application

Abstract

The application relates to the technical field of high polymer composite materials, and particularly discloses a weather-resistant basalt fiber reinforced polyamide composite material, a preparation method and application. The weather-resistant basalt fiber reinforced polyamide composite material comprises polyamide resin, surface-modified basalt fiber, an ultraviolet absorber, a hindered amine light stabilizer and an antioxidant. The surface-modified basalt fiber is obtained by sequentially modifying and treating continuous basalt fiber or basalt fiber fabric through three steps of high-temperature degumming, acid activation and chemical grafting of silane coupling agent KH-550 and succinic anhydride. The preparation method comprises the following steps: melt blending and granulating the polyamide resin, the ultraviolet absorber, the hindered amine light stabilizer and the antioxidant to obtain granules; pouring the granules into a die head; introducing the surface-modified basalt fiber into the die head for impregnation; preforming and then feeding into a mold; and finally cooling and cutting to obtain a finished composite material. The weather-resistant basalt fiber reinforced polyamide composite material has the advantages of good compatibility, good weather resistance and high mechanical properties, and can be used for photovoltaic support.

Description

Technical Field

[0001] This application relates to the field of polymer composite materials technology, and more specifically, to a weather-resistant basalt fiber reinforced polyamide composite material, its preparation method, and its application. Background Technology

[0002] Photovoltaic support structures are key load-bearing components in solar photovoltaic power generation systems. They are exposed to the outdoor environment for extended periods and must withstand the combined effects of various environmental factors, including ultraviolet radiation, high and low temperature cycles, wind and rain erosion, and sand and dust abrasion. Currently, photovoltaic support structures are mainly made of hot-dip galvanized steel or aluminum alloy, but these materials have problems such as high density, susceptibility to corrosion, and high transportation and installation costs.

[0003] Polyamide composites can overcome the problems of high density, easy corrosion, and high transportation and installation costs. In the prior art, Chinese patent application CN119610814A discloses a composite board of polyimide fiber and basalt fiber and its preparation method. It uses hydrogen peroxide solution to oxidize the blended fabric to increase the specific surface area of ​​the fiber, but the matrix system used is different from that of thermoplastic polyamide. Chinese patent application CN119307089A discloses a fiber composite photovoltaic bracket material, which focuses on improving flame retardancy and thermal conductivity, but does not propose a systematic solution for long-term outdoor UV aging. Chinese patent application CN104497578A discloses a basalt fiber reinforced polyamide composite material and its preparation method. It uses a modifier containing nitrate, strong alkali and quaternary ammonium salt to treat the surface of the fiber. However, the quaternary ammonium salt modification is mainly physical adsorption, with limited interfacial bonding strength and no UV protection function.

[0004] Therefore, the addition of basalt fiber to polyamide composites has problems such as a smooth surface, few active groups, poor interfacial compatibility with the polyamide matrix, insufficient UV aging resistance of the polyamide matrix, and the traditional "granulation + injection molding" process is prone to damaging the fiber length, resulting in low reinforcement efficiency. Acid and alkali corrosion can easily reduce fiber strength and affect reinforcement efficiency.

[0005] Therefore, there is an urgent need to develop a new basalt fiber reinforced polyamide composite material that has the advantages of good compatibility, good weather resistance, and high mechanical properties for use in photovoltaic brackets. Summary of the Invention

[0006] To prepare a new basalt fiber reinforced polyamide composite material with advantages of good compatibility, good weather resistance, and high mechanical properties for use in photovoltaic brackets, this application provides a weather-resistant basalt fiber reinforced polyamide composite material, its preparation method, and its application.

[0007] In a first aspect, this application provides a weather-resistant basalt fiber reinforced polyamide composite material, which adopts the following technical solution: A weather-resistant basalt fiber reinforced polyamide composite material, the composite material being made from the following raw materials in parts by weight: 120-200 parts polyamide resin, 100 parts surface-modified basalt fiber, 0.5-2.0 parts ultraviolet absorber, 0.5-1.5 parts hindered amine light stabilizer, and 0.5-1.5 parts antioxidant; the surface-modified basalt fiber is obtained by sequentially modifying continuous basalt fiber or basalt fiber fabric through three steps: high-temperature degumming, acid activation, and chemical grafting with silane coupling agent KH-550 and succinic anhydride.

[0008] By adopting the above technical solution, the surface-modified basalt fiber adopts a three-step continuous process of "high-temperature degumming - acid activation and regeneration - KH-550 / SA chemical grafting". The acid activation step enriches the fiber surface with silanol groups, providing conditions for subsequent grafting and improving the grafting reaction efficiency. The silane coupling agent KH-550 reacts with SA to generate a bifunctional modifier containing amino and carboxyl groups, which forms covalent and hydrogen bonds with the terminal amino and amide groups of the polyamide matrix to complete the chemical grafting. This improves the compatibility between basalt fiber and polyamide resin, increases its interfacial shear strength by more than 50%, and the high bonding force combined with the strength of the basalt fiber itself improves the mechanical properties of the composite material. The entire process can be continuously produced without solvent extraction steps, making it industrially feasible.

[0009] By combining UV absorbers, hindered amine light stabilizers, and antioxidants, the UV resistance is improved. After 2000 hours of UV aging, the mechanical properties are retained at ≥75%, meeting the 25-year outdoor service life of the photovoltaic bracket.

[0010] Preferably, during the high-temperature degumming process: the processing temperature is 450-500℃, and the processing time is 10-30 minutes.

[0011] By adopting the above technical solution, high-temperature treatment at 450-500℃ for 10-30 minutes can completely remove impurities from the surface of basalt fibers, exposing clean silicate active surfaces, providing sites for subsequent modification reactions. High-activity sites can achieve high grafting effect, thereby ensuring the compatibility of surface-modified basalt fibers with polyamide resin, and also improving the mechanical reinforcement effect of composite materials.

[0012] Preferably, during the acid activation treatment, a hydrochloric acid solution with a concentration of 0.3-0.8 mol / L is used, and the treatment time is 5-15 min.

[0013] By employing the above-mentioned technical solution, a short treatment time of 5-15 minutes with low-concentration hydrochloric acid (0.3-0.8 mol / L) generates a uniform micro-concave structure only on the fiber surface, moderately increasing the surface roughness. This allows the molten polyamide resin to fully wet the micropores on the fiber surface, forming a stable mechanical interlocking structure. This enhances the compatibility and connection between basalt fiber and polyamide resin, without excessively eroding the silicate skeleton inside the fiber, avoiding a significant decrease in the mechanical properties of the fiber itself, and ensuring the basic load-bearing capacity, thereby guaranteeing the mechanical reinforcement of the composite material. At the same time, controlling the acid activation conditions not only allows for the directional introduction of sufficient active groups such as hydroxyl groups on the fiber surface, but also provides sufficient reaction sites for the grafting reaction of the silane coupling agent KH-550, without causing redundancy of active groups due to excessive etching, ensuring uniform adhesion of the coupling agent layer, further guaranteeing the grafting effect of the surface-modified basalt fiber, thereby improving the compatibility between the fiber and resin and the mechanical property enhancement effect in the composite material.

[0014] Preferably, in the chemical grafting process of the silane coupling agent KH-550 and succinic anhydride: the silane coupling agent KH-550 and succinic anhydride are pre-reacted in an ethanol-water mixed solvent at a molar ratio of 1:0.8-1.2 for 1-2 hours, and then reacted with the fiber at a grafting temperature of 30-50℃ for 2-5 minutes, followed by curing at 120-150℃ for 3-8 minutes.

[0015] By adopting the above technical solution, the silane coupling agent KH-550 and succinic anhydride are limited in ratio and pre-reaction time, allowing them to fully generate a modified intermediate containing carboxyl groups. This avoids the self-polymerization of free silane coupling agent KH-550 and ensures that the grafted layer has active sites suitable for polyamide. Limiting the grafting temperature and time allows the modified intermediate to be evenly spread and grafted on the fiber surface, preventing local over-grafting or under-grafting, and forming a flexible transition layer of appropriate thickness. Limiting the thermosetting temperature and time allows the grafted layer to fully form stable covalent bonds with the hydroxyl groups on the fiber surface and the active groups of the polyamide matrix, constructing a continuous stress transfer path of "fiber-grafted layer-polyamide", which greatly improves interfacial compatibility and mechanical reinforcement efficiency.

[0016] Preferably, the ultraviolet absorber is a triazine ultraviolet absorber, the hindered amine light stabilizer is a high molecular weight hindered amine, and the antioxidant is a compound of hindered phenol and phosphite.

[0017] By adopting the above technical solutions, triazine UV absorbers rely on the conjugated π system and ortho-hydroxyl structure within the molecule to efficiently absorb ultraviolet rays in the 290-400nm wavelength band, converting light energy into harmless heat energy for release. This blocks the damage of ultraviolet light to the polyamide molecular chain from the source, improving weather resistance. High molecular weight hindered amines do not absorb ultraviolet light themselves, but can efficiently capture active free radicals generated by the photodegradation of polyamide, decompose hydrogen peroxide, and terminate the photoaging chain reaction. Their high molecular weight characteristics prevent the precipitation and loss of additives, and provide long-term photostable effects. Hindered phenols, as the main antioxidant, capture active free radicals generated by thermo-oxidative aging, while phosphites, as auxiliary antioxidants, decompose hydrogen peroxide. The two work together to block the thermo-oxidative degradation pathway during the processing and use of polyamide.

[0018] Preferably, the polyamide resin is polyamide 66 or polyamide 6, and the relative viscosity ηr (96% concentrated sulfuric acid, 25°C, 0.01 g / mL) is 2.4-3.0.

[0019] By adopting the above technical solution, the viscosity is limited to give the molten polyamide suitable fluidity, allowing it to fully penetrate into the surface micropores of the modified basalt fiber and complete the wetting process, thus avoiding interfacial void defects. Furthermore, the molecular chain length corresponding to this viscosity is moderate, and the amide groups of the polyamide can form a large number of hydrogen bonds and covalent bonds with the active groups grafted on the fiber surface, significantly strengthening the interfacial adhesion between the two phases. At the same time, the mechanical strength of the polyamide matrix itself is guaranteed, and stress can be efficiently transferred to the basalt fiber through the interfacial layer, ultimately achieving a significant improvement in the mechanical properties of the composite material.

[0020] Secondly, this application provides a method for preparing a weather-resistant basalt fiber reinforced polyamide composite material, using the following technical solution: A method for preparing a weather-resistant basalt fiber reinforced polyamide composite material includes the following steps: S1. Polyamide resin is melt-blended and granulated with ultraviolet absorber, hindered amine light stabilizer and antioxidant to obtain granules; S2. Pour the granules into the die head at a temperature of 290-310℃, then introduce the surface-modified basalt fiber into the die head for 3-8 minutes of immersion. After pre-forming, it enters the mold at a temperature of 270-290℃ and a traction speed of 0.2-0.5m / min. Finally, it is cooled and cut to obtain the finished composite material.

[0021] By adopting the above technical solutions, the melt impregnation temperature in pultrusion is 290-310℃, and the mold temperature is 270-290℃, ensuring low-viscosity resin impregnation and avoiding fiber thermal damage; the compression molding uses hot-melt prepreg, which is solvent-free, environmentally friendly and residue-free; it also retains the complete reinforcement structure of continuous fibers, and the mechanical properties are improved by more than 100% compared with the injection molding short fiber process, so that the finished composite material has the advantages of good compatibility, good weather resistance and high mechanical properties.

[0022] Preferably, the mold temperature is a constant temperature or a zoned temperature, with the constant temperature being 270-290℃; the zoned temperatures are a preheating zone, a gelation zone, and a curing zone, with temperatures of 260-270℃, 270-280℃, and 280-290℃ for each zone, respectively.

[0023] By adopting the above technical solution and limiting the temperature, the molding effect of the composite material can be guaranteed.

[0024] A method for preparing a weather-resistant basalt fiber reinforced polyamide composite material includes the following steps: S1. Polyamide resin is melt-blended and granulated with ultraviolet absorber, hindered amine light stabilizer and antioxidant to obtain granules; S2. The granular material is melted and extruded into a film, and then hot-pressed with surface-modified basalt fiber. During the molding process, the temperature is 280-300℃ and the pressure is 5-10MPa for 5-15 minutes. Finally, the finished composite material is obtained after cooling and demolding.

[0025] By adopting the above technical solutions, limiting the molding temperature, pressure and time ensures the integrity of the fiber structure and can also improve the density of the raw material structure, so that the composite material has the advantages of good compatibility and high mechanical properties.

[0026] Thirdly, this application provides an application of a polyamide composite material, employing the following technical solution: Application of a composite material in the fabrication of photovoltaic bracket structural components.

[0027] By adopting the above technical solution, composite materials are used in photovoltaic support structures, and their weather resistance and high mechanical strength are utilized to extend the service life of photovoltaic support structural components.

[0028] In summary, this application has the following beneficial effects: 1. The surface-modified basalt fiber adopts a three-step continuous process of "high-temperature degumming - acid activation and regeneration - KH-550 / SA chemical grafting". The acid activation step enriches the fiber surface with silanol groups, providing conditions for subsequent grafting and improving the grafting reaction efficiency. The silane coupling agent KH-550 reacts with SA to generate a bifunctional modifier containing amino and carboxyl groups, which forms covalent and hydrogen bonds with the terminal amino and amide groups of the polyamide matrix, completing the chemical grafting. This improves the compatibility between basalt fiber and polyamide resin, increasing its interfacial shear strength by more than 50%. The high bonding force, combined with the strength of the basalt fiber itself, improves the mechanical properties of the composite material. The entire process can be continuously produced without solvent extraction steps, making it industrially feasible.

[0029] 2. The combination of UV absorbers, hindered amine light stabilizers and antioxidants improves UV resistance to aging. After 2000 hours of UV aging, the mechanical properties retain ≥75%, meeting the 25-year outdoor service life of the photovoltaic bracket.

[0030] 3. In pultrusion molding, the melt impregnation temperature is 290-310℃ and the mold temperature is 270-290℃ to ensure low viscosity resin impregnation and avoid fiber thermal damage; compression molding uses hot melt prepreg, which is solvent-free, environmentally friendly and leaves no residue. Both processes retain the complete reinforcing structure of continuous fibers, and the mechanical properties are improved by more than 100% compared with the injection molding short fiber process. Attached Figure Description

[0031] Figure 1 The images shown are SEM images of basalt fibers before and after modification in Example 1 of this invention; SEM: JSM-7610F.

[0032] Figure 2 This is a comparison of the FTIR spectra of basalt fibers before and after modification in Example 1 of the present invention; where FTIR: Nicoleti S50, ATR mode. Detailed Implementation

[0033] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] Preparation example of surface-modified basalt fiber The following raw materials were purchased: continuous basalt fiber from Sichuan Aerospace Tuoxin Basalt Industry Co., Ltd.; basalt fiber plain weave fabric from Sichuan Aerospace Tuoxin Basalt Industry Co., Ltd.; and silane coupling agent KH-550 from BASF (China) Co., Ltd.

[0035] Preparation Example 1: Surface-modified basalt fibers were prepared using the following method: High-temperature degumming treatment: Continuous basalt fibers are passed through a 480℃ continuous drying oven at a speed of 1.0 m / min for 15 min to complete high-temperature degumming; the diameter of the continuous basalt fibers is 13 μm and the linear density is 1200 tex; Acid activation treatment: The fiber is then placed in a 0.5 mol / L hydrochloric acid solution impregnation tank and impregnated at 35°C for 10 min. Then it is washed with water until pH=6.5 and dried with hot air at 110°C for 3 min to complete acid activation. Chemical grafting treatment: An ethanol-water solution was prepared according to the ratio of ethanol:water = 9:1. Silane coupling agent KH-550 and succinic anhydride were added, with a molar ratio of 1:1. The mixture was pre-reacted at room temperature (25℃) for 1.5 h, resulting in a total silane concentration of 3 wt%. The modified solution was obtained. After activation, the fibers were passed through the modified solution impregnation tank at a speed of 1.0 m / min and impregnated at a grafting temperature of 35℃ for 3 min. Then, they were treated in a 140℃ hot air curing zone for 5 min, and finally cooled and wound up to obtain surface-modified basalt fibers.

[0036] Preparation Example 2: The difference between this preparation example and Preparation Example 1 is that: High-temperature degumming treatment: The basalt fiber fabric is passed through a 450℃ continuous drying oven at a speed of 0.5m / min for 30min to complete high-temperature degumming; the basalt fiber fabric has an areal density of 600g / m². 2 basalt fiber plain weave fabric; Acid activation treatment: The fiber is then placed in a 0.3 mol / L hydrochloric acid solution impregnation tank and impregnated at 35°C for 15 min. Then it is washed with water until pH=6.5 and dried with hot air at 110°C for 3 min to complete acid activation. Chemical grafting treatment: An ethanol-water solution was prepared by mixing ethanol and water in a ratio of 9:1. Silane coupling agent KH-550 and succinic anhydride were added, with a molar ratio of 1:0.8. The mixture was pre-reacted at room temperature (25℃) for 2 hours, resulting in a total silane concentration of 2wt%. The modified solution was obtained. After activation, the fibers were passed through the modified solution impregnation tank at a speed of 1.0 m / min and impregnated at a grafting temperature of 30℃ for 5 minutes. Then, the fibers were treated in a 120℃ hot air curing zone for 8 minutes, and finally cooled and wound up to obtain surface-modified basalt fibers.

[0037] Preparation Example 3: The difference between this preparation example and Preparation Example 1 is that: High-temperature degumming treatment: Continuous basalt fibers are passed through a 500℃ continuous drying oven at a speed of 2.0 m / min for 10 min to complete high-temperature degumming; Acid activation treatment: The fiber is then placed in a hydrochloric acid solution with a concentration of 0.8 mol / L and immersed at 35°C for 5 min. It is then washed with water until pH=6.5 and dried with hot air at 110°C for 3 min to complete the acid activation. Chemical grafting treatment: An ethanol-water solution was prepared by mixing ethanol and water in a ratio of 9:1. Silane coupling agent KH-550 and succinic anhydride were added, with a molar ratio of 1:1.2. The mixture was pre-reacted at room temperature (25°C) for 1 hour, resulting in a total silane concentration of 5 wt%. The activated fiber was then passed through the modified solution impregnation tank at a speed of 1.0 m / min and impregnated at a grafting temperature of 50°C for 2 minutes. It was then placed in a 150°C hot air curing zone for 3 minutes, and finally cooled and wound up to obtain surface-modified basalt fiber.

[0038] Example

[0039] Of the following raw materials, PA66 was purchased from Pingdingshan Shenma Engineering Plastics Co., Ltd.; Tinuvin 1577, Chimassorb 944, Irganox 1098 and Irgafos 168 were all purchased from BASF (China) Co., Ltd.

[0040] Example 1: A weather-resistant basalt fiber reinforced polyamide composite material: 150 kg of polyamide resin, 100 kg of surface-modified basalt fiber, 1.5 kg of UV absorber, 1 kg of hindered amine light stabilizer, and 1 kg of antioxidant were prepared. The polyamide resin was PA66 resin with a relative viscosity ηr (96% concentrated sulfuric acid, 25℃, 0.01 g / mL) of 2.6. The surface-modified basalt fiber was the same as that prepared in Preparation Example 1. The UV absorber was Tinuvin 1577, the hindered amine light stabilizer was Chimassorb 944, and the antioxidant consisted of 0.5 kg of Irganox 1098 and 0.5 kg of Irgafos 168. The preparation method is as follows: S1. Polyamide resin is mixed with UV absorber, hindered amine light stabilizer and antioxidant, and placed in a twin-screw extruder. The mixture is then melt-blended and granulated at 280°C to obtain granules. S2. Pour the granular material into the die of a single-screw extruder and melt it at a temperature of 300℃. Then, introduce the surface-modified basalt fiber into the die and impregnate it for 5 minutes. The fiber stays in the die for 5 minutes to ensure complete impregnation. After impregnation, the fiber bundle passes through a pre-forming mold and enters the die. The die temperature is kept constant at 280℃, the traction speed is 0.3m / min, and water cooling is set at the die exit. After cooling, it is cut to obtain the finished composite material.

[0041] Example 2: The difference between this example and Example 1 is that: The composition includes 120 kg of polyamide resin, 100 kg of surface-modified basalt fiber, 0.5 kg of UV absorber, 0.5 kg of hindered amine light stabilizer, and 0.5 kg of antioxidant. The polyamide resin is PA6 with a relative viscosity ηr (96% concentrated sulfuric acid, 25℃, 0.01 g / mL) of 3.0. The antioxidant consists of 0.25 kg of Irganox 1098 and 0.25 kg of Irgafos 168. The preparation method is as follows: S1. Polyamide resin is mixed with UV absorber, hindered amine light stabilizer and antioxidant, and placed in a twin-screw extruder. The mixture is then melt-blended and granulated at 280°C to obtain granules. S2. Pour the granular material into the die of a single-screw extruder and melt it at a temperature of 290℃. Then, introduce the surface-modified basalt fiber into the die and impregnate it for 8 minutes. The fiber stays in the die for 5 minutes to ensure complete impregnation. After impregnation, the fiber bundle enters the die after passing through a pre-forming mold. The die temperature is divided into three zones: preheating zone, gelation zone, and curing zone, with temperatures of 260℃, 270℃, and 280℃, respectively. The traction speed is 0.5m / min. Water cooling is set at the die exit. After cooling, the material is cut to obtain the finished composite material.

[0042] Example 3: The difference between this example and Example 1 is that: The mixture consisted of 200 kg of polyamide resin, 100 kg of surface-modified basalt fiber, 2 kg of UV absorber, 1.5 kg of hindered amine light stabilizer, and 1.5 kg of antioxidant. The polyamide resin was PA6 with a relative viscosity ηr (96% concentrated sulfuric acid, 25℃, 0.01 g / mL) of 2.4-3.0. The antioxidant consisted of 0.75 kg of Irganox 1098 and 0.75 kg of Irgafos 168. The surface-modified basalt fiber was prepared using the method described in Preparation Example 3. The preparation method is as follows: S1. Polyamide resin is mixed with UV absorber, hindered amine light stabilizer and antioxidant, and placed in a twin-screw extruder. The mixture is then melt-blended and granulated at 280°C to obtain granules. S2. Pour the granules into the die of a single-screw extruder and melt them at 310℃. Then, introduce the surface-modified basalt fibers into the die and impregnate them for 3 minutes. The fibers stay in the die for 5 minutes to ensure complete impregnation. After impregnation, the fiber bundles pass through a pre-forming mold and then enter the die. The die temperature is divided into three zones: preheating zone, gelation zone, and curing zone, with temperatures of 270℃, 280℃, and 290℃, respectively. The traction speed is 0.2 m / min. Water cooling is installed at the die exit. After cooling, the material is cut to obtain the finished composite material.

[0043] Example 4: The difference between this example and Example 1 is that: During the preparation process: S1. Polyamide resin is mixed with UV absorber, hindered amine light stabilizer and antioxidant, and placed in a twin-screw extruder. The mixture is then melt-blended and granulated at 280°C to obtain granules. S2. The granules were melt-extruded into a film at 290°C, and then the surface-modified basalt fiber hot-pressed composite prepared in Example 2 was prepared. During the molding process, the temperature was 290°C and the pressure was held at 8MPa for 10 minutes. After cooling and demolding, the finished composite material was obtained.

[0044] Example 5: The difference between this example and Example 4 is that: During the preparation process: S1. Polyamide resin is mixed with UV absorber, hindered amine light stabilizer and antioxidant, and placed in a twin-screw extruder. The mixture is then melt-blended and granulated at 280°C to obtain granules. S2. The granules were melt-extruded into a film at 290°C, and then the surface-modified basalt fiber hot-pressed composite prepared in Example 2 was prepared. During the molding process, the temperature was 280°C and the pressure was held at 10MPa for 5 minutes. After cooling and demolding, the finished composite material was obtained.

[0045] Example 6: The difference between this example and Example 4 is that: During the preparation process: S1. Polyamide resin is mixed with UV absorber, hindered amine light stabilizer and antioxidant, and placed in a twin-screw extruder. The mixture is then melt-blended and granulated at 280°C to obtain granules. S2. The granules were melt-extruded into a film at 290°C, and then the surface-modified basalt fiber hot-pressed composite prepared in Example 2 was prepared. During the molding process, the temperature was 300°C and the pressure was held at 5MPa for 15 minutes. After cooling and demolding, the finished composite material was obtained.

[0046] Comparative Example Comparative Example 1: The difference between this comparative example and Example 1 is that: The surface-modified basalt fiber was not acid-activated, and was chemically grafted with silane coupling agent KH-550 and succinic anhydride; Specifically, continuous basalt fibers are passed through a 480℃ continuous drying oven at a speed of 1.0 m / min for a residence time of 15 min to obtain surface-modified basalt fibers.

[0047] Comparative Example 2: This comparative example differs from Example 1 in that: In the raw materials, strong alkali-modified basalt fibers are used to replace surface-modified basalt fibers; The strong alkali modified basalt fiber is prepared as follows: 8 parts by weight of NaOH, 3 parts by weight of potassium nitrate, and 80 parts by weight of water are weighed, mixed and stirred evenly to obtain a treatment solution. The basalt fiber is placed in the treatment solution and treated at 60℃ for 2 hours to obtain the finished product.

[0048] Comparative Example 3: This comparative example differs from Example 1 in that: No UV absorbers, hindered amine light stabilizers, or antioxidants were added to the raw materials.

[0049] Comparative Example 4: This comparative example differs from Example 1 in that: The raw material used is chopped basalt fiber, with an average length of 3mm, which is injection molded.

[0050] Application examples Application Example 1: The composite material prepared in Example 1 is used in the fabrication of photovoltaic bracket structural components.

[0051] Performance testing 1. Strength testing Composite materials were prepared using the methods of Examples 1 and 4 and Comparative Examples 1-4, respectively. Tensile strength was tested according to GB / T1040.5-2008, and flexural strength and flexural modulus were recorded according to GB / T9341-2008.

[0052] 2. Anti-aging test Composite materials were prepared using the methods of Examples 1 and 4 and Comparative Examples 1-4, respectively, in accordance with GB / T16422.3-2022. The testing conditions were as follows: xenon lamp, irradiance 0.51 W / m2@340 nm, black panel temperature 65℃, relative humidity 50%, water spraying for 18 min / 102 min cycles, for a total time of 2000 h. Then, the tensile strength was tested again, the tensile strength retention rate was calculated, and the data were recorded.

[0053] Table 1 Performance Test Table

[0054] Combining Examples 1 and 4 with Table 1, Figure 1 and Figure 2 It can be seen that the composite material has high tensile strength, high flexural strength, high flexural modulus, and high retention rate, indicating that the composite material has good compatibility, good weather resistance, and high mechanical properties.

[0055] As can be seen from Example 1 and Comparative Example 1, and Table 1, the three-step surface modification increased the tensile strength by 47.3% and the UV aging retention rate from 68.5% to 81.5%, demonstrating that the modification significantly improved the interfacial bonding and aging resistance.

[0056] As can be seen from Example 1 and Comparative Example 2, and Table 1, the weakly acidic system (HCl activation) of this application has a higher fiber strength retention rate compared to the strong alkali system.

[0057] As can be seen from Example 1 and Comparative Example 3, and Table 1, the combination of UV absorber, hindered amine light stabilizer and antioxidant can improve the weather resistance of composite material.

[0058] As can be seen from Example 1 and Comparative Example 4, and in conjunction with Table 1, ordinary injection-molded chopped basalt fibers affect the strength and mechanical properties of the finished composite material.

[0059] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A weather-resistant basalt fiber reinforced polyamide composite material, characterized in that, The composite material is made from the following raw materials in parts by weight: 120-200 parts polyamide resin, 100 parts surface-modified basalt fiber, 0.5-2.0 parts ultraviolet absorber, 0.5-1.5 parts hindered amine light stabilizer, and 0.5-1.5 parts antioxidant. Surface-modified basalt fiber is prepared by a three-step modification process, namely, high-temperature degumming, acid activation, and chemical grafting of silane coupling agent KH-550 and succinic anhydride onto continuous basalt fiber or basalt fiber fabric.

2. The weather-resistant basalt fiber reinforced polyamide composite material according to claim 1, characterized in that: During the high-temperature degumming process: the processing temperature is 450-500℃, and the processing time is 10-30 minutes.

3. The weather-resistant basalt fiber reinforced polyamide composite material according to claim 1, characterized in that: During the acid activation treatment: a hydrochloric acid solution with a concentration of 0.3-0.8 mol / L is used, and the treatment time is 5-15 min.

4. The weather-resistant basalt fiber reinforced polyamide composite material according to claim 1, characterized in that: During the chemical grafting process of the silane coupling agent KH-550 and succinic anhydride: the silane coupling agent KH-550 and succinic anhydride are pre-reacted in an ethanol-water mixed solvent at a molar ratio of 1:0.8-1.2 for 1-2 hours, and then reacted with the fiber at a grafting temperature of 30-50℃ for 2-5 minutes, followed by curing at 120-150℃ for 3-8 minutes.

5. The weather-resistant basalt fiber reinforced polyamide composite material according to claim 1, characterized in that, The ultraviolet absorber is a triazine ultraviolet absorber, the hindered amine light stabilizer is a high molecular weight hindered amine, and the antioxidant is a compound of hindered phenol and phosphite.

6. The weather-resistant basalt fiber reinforced polyamide composite material according to claim 1, characterized in that, The polyamide resin is polyamide 66 or polyamide 6, and the relative viscosity ηr (96% concentrated sulfuric acid, 25℃, 0.01g / mL) is 2.4-3.

0.

7. A method for preparing a weather-resistant basalt fiber reinforced polyamide composite material according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Polyamide resin is melt-blended and granulated with ultraviolet absorber, hindered amine light stabilizer and antioxidant to obtain granules; S2. Pour the granules into the die head at a temperature of 290-310℃, then introduce the surface-modified basalt fiber into the die head for 3-8 minutes of immersion. After pre-forming, it enters the mold at a temperature of 270-290℃ and a traction speed of 0.2-0.5m / min. Finally, it is cooled and cut to obtain the finished composite material.

8. The method for preparing a weather-resistant basalt fiber reinforced polyamide composite material according to claim 7, characterized in that, The mold temperature is either constant or zoned. The constant temperature is 270-290℃. The zoned temperatures are for the preheating zone, gelation zone, and curing zone, with temperatures of 260-270℃, 270-280℃, and 280-290℃, respectively.

9. A method for preparing a weather-resistant basalt fiber reinforced polyamide composite material according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Polyamide resin is melt-blended and granulated with ultraviolet absorber, hindered amine light stabilizer and antioxidant to obtain granules; S2. The granular material is melted and extruded into a film, and then hot-pressed with surface-modified basalt fiber. During the molding process, the temperature is 280-300℃ and the pressure is 5-10MPa for 5-15 minutes. Finally, the finished composite material is obtained after cooling and demolding.

10. The application of the composite material according to any one of claims 1-6 or the composite material prepared by the preparation method according to any one of claims 7-9 in the preparation of photovoltaic bracket structural components.

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