A gas delivery glass reinforced pipe line and method of manufacture

Abstract

The application belongs to the technical field of glass steel pipeline preparation, and relates to a gas conveying glass steel pipeline and a preparation method, which comprises the following steps: S1: epoxy resin glue solution preparation: adding organic silicon epoxy resin, hydroxyl-terminated hyperbranched polyester, methylhexahydrophthalic anhydride and a curing accelerator into 100 parts of bisphenol A type epoxy resin, uniformly mixing, and defoaming to obtain the epoxy resin glue solution; S2: preparation of modified continuous glass fiber: sequentially immersing activated glass fiber in a polyethylene imine solution, drying, immersing in organic modified montmorillonite dispersion liquid, and drying to obtain the modified continuous glass fiber; and S3: immersing the modified continuous glass fiber in the epoxy resin glue solution, winding the modified continuous glass fiber on an inner liner pipe through a winding machine to form a pipe blank, and gradiently curing to obtain the glass steel pipeline. The prepared glass steel pipeline has excellent high pressure bearing capacity and gas barrier performance.

Description

Technical Field

[0001] This invention belongs to the field of fiberglass pipeline manufacturing technology, and relates to a gas transmission fiberglass pipeline and its manufacturing method. It is used in the preparation and application of high-pressure gas (especially hydrogen) long-distance transmission pipelines, which can significantly improve the gas barrier performance and mechanical pressure bearing performance of fiberglass pipelines, and reduce the safety hazards and economic losses caused by high-pressure small molecule gas infiltration and leakage. Background Technology

[0002] In high-pressure gas transportation scenarios, pipelines not only need excellent pressure resistance and structural stability, but also extremely high gas barrier properties to prevent safety hazards and economic losses caused by gas infiltration and leakage. However, in conventional fiberglass pipelines, microscopic defects are easily formed at the interface between the resin matrix and glass fiber, and the resin matrix itself has limited barrier capabilities against high-pressure gases (such as hydrogen and natural gas), resulting in high gas permeability, which makes it difficult to meet the engineering requirements of high-pressure long-distance pipelines.

[0003] The core of the conventional manufacturing method for fiberglass pipelines lies in the process of thoroughly impregnating untwisted glass fiber rovings or woven glass fiber fabric with resin using an impregnation machine, followed by subsequent processes such as molding and curing. The selection of the glass fiber reinforcement and the wetting effect of the resin directly affect the mechanical and barrier properties of the pipeline, and are also key manufacturing steps for adapting to high-pressure gas transportation scenarios.

[0004] Patent application CN116535714A discloses a method for preparing a highly transparent, hydrophobic, and moisture-resistant glass fiber reinforced composite material, comprising the following steps: (1) mixing organosilicon-modified alicyclic epoxy resin and bisphenol A type epoxy resin to obtain a resin mixture; (2) adding a curing agent and an accelerator to the resin mixture and mixing them evenly to obtain an epoxy resin adhesive; (3) impregnating glass fiber material with the epoxy resin adhesive and then heating the impregnated glass fiber material to obtain the highly transparent, hydrophobic, and moisture-resistant glass fiber reinforced composite material.

[0005] In this technical solution, the compound system of organosilicon-modified alicyclic epoxy resin and bisphenol A type epoxy resin relies solely on the fact that organosilicon-modified alicyclic epoxy resin is difficult to form a dense interfacial bond with glass fiber materials. This cannot compensate for the microscopic defects at the interface between resin and glass fiber materials in conventional fiberglass composite materials, resulting in a high gas permeability and failing to meet the stringent engineering requirements of high-pressure gas transmission fiberglass pipelines. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art, solve the technical problems of poor gas barrier performance and high gas permeability of existing pipes, and provide a gas transportation fiberglass pipeline and its preparation method.

[0007] To achieve the above-mentioned objectives, this invention provides a method for preparing a gas transport fiberglass pipeline, the technical solution of which includes the following steps: S1: Preparation of epoxy resin solution: By weight, add 5-15 parts of organosilicon epoxy resin, 3-8 parts of hydroxyl-terminated hyperbranched polyester, 40-50 parts of methylhexahydrophthalic anhydride and 0.5-1.5 parts of curing accelerator to 100 parts of bisphenol A type epoxy resin, mix at 50-60℃, degas, and obtain epoxy resin solution. S2: Preparation of modified continuous glass fibers: (1) After heat treatment and etching, the glass fiber material is washed, sprayed with silane coupling agent pre-hydrolysis solution, and dried to obtain activated glass fiber; (2) The activated glass fiber is impregnated and dried in polyethyleneimine solution, and then impregnated and dried in organic modified montmorillonite dispersion to form one cycle; the cycle is repeated at least once to obtain modified continuous glass fiber; S3: Modified continuous glass fiber is impregnated in epoxy resin solution, and the amount of epoxy resin solution adhering is controlled to be 28%~33% of the mass of modified continuous glass fiber. It is then wound onto the inner lining pipe by a winding machine to form a pipe blank, and then cured in a gradient to obtain a fiberglass pipeline.

[0008] This invention uses bisphenol A type epoxy resin as the matrix, adds organosilicon epoxy resin and hydroxyl-terminated hyperbranched polyester, and then impregnates modified continuous glass fibers in epoxy resin solution. After subsequent curing, methyl hexahydrophthalic anhydride, bisphenol A type epoxy resin and hydroxyl-terminated hyperbranched polyester jointly construct a dense three-dimensional cross-linked network. The curing accelerator regulates the curing process, ensures the pot life of the solution, and is suitable for industrial continuous production.

[0009] The siloxane segments in the organosilicon epoxy resin involved in this invention have low surface energy, which migrate to the resin surface during curing to form a continuous and dense silicon-rich barrier layer, significantly extending the diffusion path of gas molecules. After the glass fiber material is sprayed with a silane coupling agent pre-hydrolyzed solution, the alkoxy groups of the silane coupling agent hydrolyze to generate silanol groups, which undergo a dehydration condensation reaction with the silanol groups on the glass fiber surface, constructing a covalently bonded transition layer between the glass fiber and the organic modified layer, further improving the interfacial bonding strength. After being successively impregnated and cyclically modified with polyethyleneimine solution and organic modified montmorillonite dispersion, the organic modified montmorillonite sheets will be oriented and arranged along the glass fiber axis during electrostatic adsorption, forming a nano-barrier layer with a "brick-and-mortar" structure.

[0010] The organosilicon epoxy resin described in this invention is a tetrafunctional organosilicon epoxy resin.

[0011] The tetrafunctional organosilicon epoxy resin involved in this invention can significantly increase the crosslinking density of the resin system, further reduce the gap between resin molecular chains, and reduce gas permeation channels; at the same time, its siloxane backbone content is higher, and the silicon-rich barrier layer formed after curing is more dense and uniform.

[0012] In the silane coupling agent pre-hydrolyzed solution of the present invention, the silane coupling agent used is selected from at least one of silane KH-560, silane KH-550, and silane KH-792.

[0013] The curing accelerator described in this invention is N,N-dimethylbenzylamine.

[0014] Before using the polyethyleneimine solution described in this invention, the pH should be adjusted to 8.0~8.5.

[0015] The polyethyleneimine solution described in this invention has a molecular weight of 600-1800 and a concentration of 5-15 g / L.

[0016] The pure polyethyleneimine aqueous solution involved in this invention is strongly alkaline. Under these conditions, the polyethyleneimine molecular chains are coiled up due to intramolecular hydrogen bonding, making it difficult for them to penetrate into the micro-etched structure of the glass fiber surface. After adjusting the pH to 8.0-8.5, some of the amino groups on the polyethyleneimine molecular chains are protonated, and the positively charged molecular chains fully extend due to electrostatic repulsion, allowing them to fully penetrate into the micropores and grooves on the fiber surface. A large number of amino groups on the molecular chains can bond with the silanol groups on the etched glass fiber surface, firmly adhering to the fiber surface and introducing a uniform positively charged layer, providing active sites for the subsequent electrostatic adsorption of organically modified montmorillonite.

[0017] The concentration of the organically modified montmorillonite dispersion described in this invention is 10~20 g / L.

[0018] The method for preparing organically modified montmorillonite in the organically modified montmorillonite dispersion of the present invention includes the following steps: Sodium-based montmorillonite was uniformly dispersed in water and heated to 60-80℃. Hexadecyltrimethylammonium bromide was added at 0.3-0.4 times the mass of sodium-based montmorillonite. The mixture was kept at a constant temperature and mixed for 2-4 hours. The solid and liquid were separated, washed, and sieved to obtain organically modified montmorillonite.

[0019] In step S2 (1) of the present invention, the heat treatment temperature is 380~420℃, the etching uses a nitric acid solution with a mass fraction of 5%~7%, and the etching time is 3~5min.

[0020] The heat treatment involved in this invention can effectively remove organic wetting agents from the surface of glass fibers, preventing them from hindering the bonding between the fibers and resin. The temperature range of 380~420℃ ensures complete desizing without damaging the bulk strength of the glass fibers. Nitric acid etching can form a moderately rough, uneven structure on the fiber surface, increasing the contact area between the fibers and resin and improving mechanical interlocking force. At the same time, etching can break the silicon-oxygen bonds on the fiber surface, generating a large number of active silanol groups, providing reaction sites for the subsequent adhesion of polyethyleneimine.

[0021] The inner lining tube described in this invention is selected from polytetrafluoroethylene tubes or high-density polyethylene tubes.

[0022] The inner lining tube described in this invention is a polytetrafluoroethylene (PTFE) tube.

[0023] The inner liner tube described in this invention undergoes surface pretreatment before use, specifically plasma treatment.

[0024] The glass fiber material described in this invention is glass fiber roving without twist.

[0025] In step S1 of the present invention, after adding the terminal hydroxyl hyperbranched polyester, the step of adding 5-7 parts by mass of terminal epoxy allyl polyether is further included.

[0026] The epoxy-terminated allyl polyether involved in this invention can directly participate in the crosslinking reaction. Flexible polyether segments are uniformly introduced into the three-dimensional network of the resin. Through segment slippage and energy dissipation, impact energy is absorbed, effectively suppressing the generation and propagation of microcracks inside the resin under high-pressure cyclic loading without reducing the crosslinking density and strength of the resin.

[0027] The present invention also provides a gas delivery fiberglass pipeline prepared by the above preparation method.

[0028] This fiberglass pipeline consists of a permanent inner lining and a fiberglass reinforced composite layer wound around it. By loading silane-grafted polyethyleneimine-organomontmorillonite multilayer nanosheets onto the surface of the fiberglass and impregnating it with epoxy resin rich in silicon-modified components, a strong and defect-free nanocomposite interface is constructed between the fiberglass and the resin after winding and curing. At the same time, a dense cross-linked network and multi-level barrier structure are formed inside the resin matrix, ultimately producing a high-pressure gas transmission fiberglass pipeline with excellent gas barrier properties, high pressure resistance, and long-term operational stability.

[0029] Compared with existing technologies, the advantages of this invention are as follows: Through silane grafting and layer-by-layer self-assembly of polyethyleneimine / montmorillonite, a strongly bonded, defect-free nanocomposite interface is constructed on the surface of glass fiber, effectively filling microscopic defects at the fiber-resin interface and inhibiting interface debonding and microcrack propagation under high-pressure loads. The introduction of organosilicon epoxy resin into the resin matrix forms a silicon-rich barrier layer, which, combined with hyperbranched polyester, constructs a high-crosslink density network, significantly extending the diffusion path of gas molecules. The resulting fiberglass pipeline possesses extremely low gas permeability, high pressure resistance, and long-term operational stability, meeting the stringent engineering requirements of long-distance gas (such as hydrogen and natural gas) pipelines. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the embodiments.

[0031] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0032] The preferred tetrafunctional silicone epoxy resin is Shin-Etsu KR-470 tetrafunctional oligomeric silicone epoxy resin; the molecular weight of polyethyleneimine is 600~1800; special note: the epoxy resin solution should be prepared and used immediately (potential period ≥4.5h); the circumferential winding angle is 85°~90°, and the helical winding angle is ±45°.

[0033] Example 1 The method for preparing the gas transmission fiberglass pipeline involved in this embodiment includes the following steps: S1: In a vacuum reactor equipped with mechanical stirring, add 1000g of E-51 bisphenol A type epoxy resin, start stirring and heat to 50℃, add 100g of tetrafunctional organosilicon epoxy resin, stir at 800r / min for 10min, add 50g of hydroxyl-terminated hyperbranched polyester, stir for 10min, add 450g of methylhexahydrophthalic anhydride and 10g of N,N-dimethylbenzylamine, continue stirring for 15min, turn on the vacuum system, control the vacuum degree to -0.09MPa, vacuum degas for 15min, cool to room temperature to obtain epoxy resin solution, the solution has a pot life of ≥4.5h; S2: (1) The alkali-free glass fiber untwisted roving (2400 tex) is continuously passed through a tubular heating furnace with a set temperature of 400℃ at a linear speed of 1 m / min. The constant temperature section is held for 4 min. Then it is immediately introduced into a bath of 7% nitric acid solution. After soaking at 25℃ for 3 min, it is drained and then introduced into a deionized water washing tank to be washed until the pH of the washing solution is 7.0. The silane coupling agent pre-hydrolysis solution is sprayed and dried at 110℃ for 5 min to obtain activated glass fiber. (2) Prepare a 10 g / L polyethyleneimine aqueous solution, slowly adjust the pH to 8.5 with 0.1 mol / L dilute hydrochloric acid, pass the activated glass fiber through it at a speed of 1 m / min, stay for 4 min, dry at 110℃ for 2 min, and then pass it through a 15 g / L organic modified montmorillonite dispersion (prepared by ultrasonic dispersion at 300W, 40 kHz for 30 min) at a speed of 1 m / min, while maintaining gentle ultrasonic assistance at 40 kHz, stay for 4 min, and dry at 120℃ for 3 min to obtain modified continuous glass fiber; S3: Modified continuous glass fiber is continuously passed through the epoxy resin solution in S1, and the amount of epoxy resin solution adhering is controlled to be 30% of the mass of modified continuous glass fiber. The impregnated modified continuous glass fiber is drawn to a CNC winding machine and wound with a constant tension (15N / bundle) using a circumferential and spiral composite winding process on the pre-treated inner liner tube (the inner liner tube is selected from polytetrafluoroethylene tube, with a wall thickness of 0.5mm, and is plasma treated before use). The winding traction speed is matched to 20m / min. The number of winding layers is controlled according to the preset wall thickness of the product, and the wall thickness deviation is ≤±5%. During the winding process, online preheating is used, and the surface temperature of the tube blank is kept constant at 70℃. The wound core mold tube blank is sent to a programmable temperature-controlled curing oven, first kept at 80℃ for 2h to complete the initial curing, and then the temperature is increased to 150℃ at 1℃ / min and kept for 2h. It is then naturally cooled to room temperature to obtain the fiberglass pipeline.

[0034] The preparation method of the silane coupling agent pre-hydrolyzed solution is as follows: silane KH-560 and ethanol aqueous solution (anhydrous ethanol and deionized water volume ratio of 95:5) with a mass ratio of 3:97 are mixed evenly, the pH is adjusted to 4.5 with 0.1 mol / L dilute hydrochloric acid, the temperature is raised to 55℃, and hydrolysis is carried out for 120 min to obtain the silane coupling agent pre-hydrolyzed solution.

[0035] The preparation method of organic modified montmorillonite dispersion is as follows: Sodium-based montmorillonite with a sheet thickness of 1~2nm and a sheet diameter of 100~500nm is added to deionized water at a solid-liquid ratio of 1g:5mL. The mixture is ultrasonically dispersed at 300W and 40kHz for 30min. The temperature is raised to 60℃, and cetyltrimethylammonium bromide with a mass of 0.35 times that of sodium-based montmorillonite is added. The mixture is stirred and mixed for 4h, centrifuged, washed, dried, ground, and sieved to obtain organic modified montmorillonite.

[0036] Example 2 The method for preparing the gas transmission fiberglass pipeline involved in this embodiment includes the following steps: S1: In a vacuum reactor equipped with mechanical stirring, add 1000g of E-51 bisphenol A type epoxy resin, start stirring and heat to 60℃, add 50g of tetrafunctional organosilicon epoxy resin, stir at 800r / min for 10min, add 30g of hydroxyl-terminated hyperbranched polyester, stir for 10min, add 400g of methylhexahydrophthalic anhydride and 5g of N,N-dimethylbenzylamine, continue stirring for 15min, turn on the vacuum system, control the vacuum degree to -0.09MPa, vacuum degas for 15min, cool to room temperature to obtain epoxy resin solution, the solution has a pot life of ≥4.5h; S2: (1) The alkali-free glass fiber untwisted roving (2400 tex) is continuously passed through a tubular heating furnace with a set temperature of 420℃ at a linear speed of 1 m / min. The constant temperature section is held for 4 min. Then it is immediately introduced into a bath of 5% nitric acid solution and immersed at 25℃ for 5 min. After draining, it is introduced into a deionized water washing tank to be washed until the pH of the washing solution is 7.0. The silane coupling agent pre-hydrolysis solution is sprayed and dried at 110℃ for 5 min to obtain activated glass fiber. (2) Prepare a 5 g / L polyethyleneimine aqueous solution, slowly adjust the pH to 8.5 with 0.1 mol / L dilute hydrochloric acid, then pass the activated glass fiber through it at a speed of 1 m / min for 4 min, dry it at 110℃ for 2 min, then pass it through a 10 g / L organic modified montmorillonite dispersion (prepared by ultrasonic dispersion at 300W, 40kHz for 30 min) at a speed of 1 m / min, while maintaining gentle ultrasonic assistance at 40 kHz, for 4 min, dry it at 120℃ for 3 min, continue to pass it through a 5 g / L polyethyleneimine aqueous solution (pH 8.5) at a speed of 1 m / min, for 4 min, dry it at 110℃ for 2 min, then pass it through a 10 g / L organic modified montmorillonite dispersion (prepared by ultrasonic dispersion at 300W, 40kHz for 30 min) at a speed of 1 m / min, while maintaining gentle ultrasonic assistance at 40 kHz, for 4 min, dry it at 120℃ for 3 min, to obtain modified continuous glass fiber; S3: Modified continuous glass fiber is continuously passed through the epoxy resin solution in S1, and the amount of epoxy resin solution adhering is controlled to be 28% of the mass of modified continuous glass fiber. The impregnated modified continuous glass fiber is drawn to a CNC winding machine and wound with a circumferential and spiral composite winding process at a constant tension (15N / bundle) onto the pretreated inner liner tube (the inner liner tube is selected from polytetrafluoroethylene tube, with a wall thickness of 0.5mm, and is plasma treated before use). The winding traction speed is matched to 20m / min. The number of winding layers is controlled according to the preset wall thickness of the product, and the wall thickness deviation is ≤±5%. During the winding process, online preheating is used, and the surface temperature of the tube blank is kept constant at 70℃. The wound core mold tube blank is sent into a program-controlled temperature curing oven. It is first kept at 80℃ for 2 hours to complete the initial curing, and then the temperature is increased to 150℃ at 1℃ / min and kept for 2 hours. It is then naturally cooled to room temperature to obtain the fiberglass pipeline.

[0037] The preparation method of the silane coupling agent pre-hydrolyzed solution involved in this embodiment is as follows: silane coupling agent and ethanol aqueous solution (anhydrous ethanol and deionized water volume ratio of 95:5) with a mass ratio of 5:95 are mixed evenly, the pH is adjusted to 5.0 with 0.1 mol / L dilute hydrochloric acid, the temperature is raised to 65℃, and hydrolysis is carried out for 100 min to obtain the silane coupling agent pre-hydrolyzed solution.

[0038] The silane coupling agents involved in this embodiment are silane KH-550 and silane KH-792 in a mass ratio of 1:1.

[0039] The organic modified montmorillonite dispersion involved in this embodiment is prepared by adding sodium-based montmorillonite with a sheet thickness of 1-2 nm and a sheet diameter of 100-500 nm to deionized water at a solid-liquid ratio of 1 g: 5 mL, ultrasonically dispersed at 300 W and 40 kHz for 30 min, heated to 80 °C, and adding hexadecyltrimethylammonium bromide at 0.4 times the mass of sodium-based montmorillonite. The mixture is stirred and mixed for 2 h, centrifuged, washed, dried, ground, and sieved to obtain organic modified montmorillonite.

[0040] Example 3 The method for preparing the gas transmission fiberglass pipeline involved in this embodiment includes the following steps: S1: In a vacuum reactor equipped with mechanical stirring, add 1000g of E-51 bisphenol A type epoxy resin, start stirring and heat to 60℃, add 150g of tetrafunctional organosilicon epoxy resin, stir at 800r / min for 10min, add 80g of hydroxyl-terminated hyperbranched polyester, stir for 10min, add 500g of methylhexahydrophthalic anhydride and 15g of N,N-dimethylbenzylamine, continue stirring for 15min, turn on the vacuum system, control the vacuum degree to -0.09MPa, vacuum degas for 15min, cool to room temperature to obtain epoxy resin solution, the solution has a pot life of ≥4.5h; S2: (1) The alkali-free glass fiber untwisted roving (2400 tex) is continuously passed through a tubular heating furnace with a set temperature of 380℃ at a linear speed of 1 m / min. The constant temperature section is held for 4 min. Then it is immediately introduced into a bath of 5% nitric acid solution and immersed at 25℃ for 5 min. After draining, it is then introduced into a deionized water washing tank to be washed until the pH of the washing solution is 7.0. The silane coupling agent pre-hydrolysis solution is sprayed and dried at 110℃ for 5 min to obtain activated glass fiber. (2) Prepare a 15 g / L polyethyleneimine aqueous solution, slowly adjust the pH to 8.0 with 0.1 mol / L dilute hydrochloric acid, pass the activated glass fiber through it at a speed of 1 m / min, stay for 4 min, dry at 110℃ for 2 min, and then pass it through a 20 g / L organic modified montmorillonite dispersion (prepared by ultrasonic dispersion at 300W, 40 kHz for 30 min) at a speed of 1 m / min, while maintaining gentle ultrasonic assistance at 40 kHz, stay for 4 min, and dry at 120℃ for 3 min to obtain modified continuous glass fiber; S3: Modified continuous glass fiber is continuously passed through the epoxy resin solution in S1, and the amount of epoxy resin solution adhering is controlled to be 33% of the mass of modified continuous glass fiber. The impregnated modified continuous glass fiber is drawn to a CNC winding machine and wound with a circumferential and spiral composite winding process at a constant tension (15N / bundle) onto the pretreated inner liner tube (the inner liner tube is selected from polytetrafluoroethylene tube, with a wall thickness of 0.5mm, and is plasma treated before use). The winding traction speed is matched to 20m / min. The number of winding layers is controlled according to the preset wall thickness of the product, and the wall thickness deviation is ≤±5%. During the winding process, online preheating is used, and the surface temperature of the tube blank is kept constant at 70℃. The wound core mold tube blank is sent into a program-controlled temperature curing oven. It is first kept at 80℃ for 2 hours to complete the initial curing, and then the temperature is increased to 150℃ at 1℃ / min and kept for 2 hours. It is then naturally cooled to room temperature to obtain the fiberglass pipeline.

[0041] The preparation method of the silane coupling agent pre-hydrolyzed solution involved in this embodiment is as follows: silane coupling agent and ethanol aqueous solution (anhydrous ethanol and deionized water volume ratio of 95:5) with a mass ratio of 5:95 are mixed evenly, the pH is adjusted to 5.0 with 0.1 mol / L dilute hydrochloric acid, the temperature is raised to 65℃, and hydrolysis is carried out for 100 min to obtain the silane coupling agent pre-hydrolyzed solution.

[0042] The silane coupling agents involved in this embodiment are silane KH-560 and silane KH-792 in a mass ratio of 1:1.

[0043] The organic modified montmorillonite dispersion involved in this embodiment is prepared by adding sodium-based montmorillonite with a sheet thickness of 1-2 nm and a sheet diameter of 100-500 nm to deionized water at a solid-liquid ratio of 1 g: 5 mL, ultrasonically dispersed at 300 W and 40 kHz for 30 min, heated to 80 °C, and adding hexadecyltrimethylammonium bromide at 0.3 times the mass of sodium-based montmorillonite. The mixture is stirred and mixed for 2 h, centrifuged, washed, dried, ground, and sieved to obtain organic modified montmorillonite.

[0044] Example 4 The difference between this embodiment and embodiment 3 is as follows: S1: In a vacuum reactor equipped with mechanical stirring, add 1000g of E-51 bisphenol A type epoxy resin, start stirring and heat to 60℃, add 100g of tetrafunctional organosilicon epoxy resin, stir at 800r / min for 10min, add 50g of hydroxyl-terminated hyperbranched polyester and 50g of epoxy-terminated allyl polyether, stir for 10min, add 450g of methylhexahydrophthalic anhydride and 10g of N,N-dimethylbenzylamine, continue stirring for 15min, turn on the vacuum system, control the vacuum degree to -0.09MPa, vacuum degas for 15min, cool to room temperature to obtain epoxy resin solution, the solution has a pot life ≥4.5h; Everything else is the same as in Example 3.

[0045] Example 5 The difference between this embodiment and embodiment 4 is that: The amount of terminal epoxy allyl polyether used is 70g; The rest is the same as in Example 4.

[0046] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: S2: The alkali-free glass fiber roving (2400 tex) is continuously passed through a tubular heating furnace with a set temperature of 400℃ at a linear speed of 1 m / min. The constant temperature section is held for 4 min. Then, it is immediately introduced into a bath of 7% nitric acid solution and immersed at 25℃ for 3 min. After draining, it is introduced into a deionized water washing tank to be washed until the pH of the washing solution is 7.0. The silane coupling agent pre-hydrolysis solution is sprayed on and dried at 110℃ for 5 min to obtain modified continuous glass fiber. Everything else is the same as in Example 1.

[0047] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: S1: In a vacuum reactor equipped with mechanical stirring, add 1000g of E-51 bisphenol A type epoxy resin, start stirring and heat to 50℃, add 50g of hydroxyl-terminated hyperbranched polyester, stir for 10min, add 450g of methylhexahydrophthalic anhydride and 10g of N,N-dimethylbenzylamine, continue stirring for 15min, turn on the vacuum system, control the vacuum degree to -0.09MPa, vacuum degas for 15min, cool to room temperature, and obtain epoxy resin solution with a pot life of ≥4.5h; Everything else is the same as in Example 1.

[0048] Comparative Example 3 The method for preparing the gas transmission fiberglass pipeline in this comparative example includes the following steps: S1: In a vacuum reactor equipped with mechanical stirring, add 1000g of E-51 bisphenol A type epoxy resin, start stirring and heat to 50℃, add 100g of tetrafunctional organosilicon epoxy resin, stir at 800r / min for 10min, add 50g of hydroxyl-terminated hyperbranched polyester, stir for 10min, add 450g of methylhexahydrophthalic anhydride and 10g of N,N-dimethylbenzylamine, continue stirring for 15min, add 30g of organically modified montmorillonite, stir and mix for 30min, turn on the vacuum system, control the vacuum degree to -0.09MPa, vacuum degas for 15min, cool to room temperature to obtain epoxy resin solution, the solution has a pot life ≥4.5h; S2: Alkali-free glass fiber roving (2400 tex) is continuously passed through a tubular heating furnace at a set temperature of 400℃ at a linear speed of 1 m / min. The constant temperature section is held for 4 min. Then, it is immediately introduced into a bath of 7% nitric acid solution and immersed at 25℃ for 3 min. After draining, it is then introduced into a deionized water washing tank to be washed until the pH of the washing solution is 7.0. Silane coupling agent pre-hydrolysis solution is sprayed on and dried at 110℃ for 5 min to obtain modified continuous glass fiber. S3: Modified continuous glass fiber is continuously passed through the epoxy resin solution in S1, and the amount of epoxy resin solution adhering is controlled to be 30% of the mass of modified continuous glass fiber. The impregnated modified continuous glass fiber is drawn to a CNC winding machine and wound with a constant tension (15N / bundle) using a circumferential and spiral composite winding process on the pre-treated inner liner tube (the inner liner tube is selected from polytetrafluoroethylene tube, with a wall thickness of 0.5mm, and is plasma treated before use). The winding traction speed is matched to 20m / min. The number of winding layers is controlled according to the preset wall thickness of the product, and the wall thickness deviation is ≤±5%. During the winding process, online preheating is used, and the surface temperature of the tube blank is kept constant at 70℃. The wound core mold tube blank is sent to a programmable temperature-controlled curing oven, first kept at 80℃ for 2h to complete the initial curing, and then the temperature is increased to 150℃ at 1℃ / min and kept for 2h. It is then naturally cooled to room temperature to obtain the fiberglass pipeline.

[0049] The preparation method of the silane coupling agent pre-hydrolyzed solution is as follows: silane KH-560 and ethanol aqueous solution (anhydrous ethanol and deionized water volume ratio of 95:5) with a mass ratio of 3:97 are mixed evenly, the pH is adjusted to 4.5 with 0.1 mol / L dilute hydrochloric acid, the temperature is raised to 55℃, and hydrolysis is carried out for 120 min to obtain the silane coupling agent pre-hydrolyzed solution.

[0050] The preparation method of organic modified montmorillonite is as follows: Sodium-based montmorillonite with a sheet thickness of 1~2nm and a sheet diameter of 100~500nm is added to deionized water at a solid-liquid ratio of 1g:5mL. The mixture is ultrasonically dispersed at 300W and 40kHz for 30min. The temperature is raised to 60℃, and cetyltrimethylammonium bromide with a mass of 0.35 times that of sodium-based montmorillonite is added. The mixture is stirred and mixed for 4h, centrifuged, washed, dried, ground, and sieved to obtain organic modified montmorillonite.

[0051] Performance testing The fiberglass pipelines prepared in Examples 1-5 and Comparative Examples 1-3, with a wall thickness of 8mm and a diameter of DN100, were subjected to performance tests. The reference standards were GB / T 1458-2023, GB / T 5350-2005, and GB / T 1038.1-2022. Among them, the H2 permeability test was conducted using the pressure difference method. The test gas was high-purity hydrogen with a purity ≥99.999%, and the equilibrium gas was high-purity nitrogen. The test temperature was kept constant at 25℃±0.5℃. Before the test, the low-pressure chamber was evacuated to a vacuum degree ≤1Pa and maintained for degassing for more than 8 hours. The test pressure on the upstream hydrogen side was kept constant at 3.5MPa, and the downstream low-pressure chamber was at atmospheric pressure of 0.1MPa. The results are shown in Table 1 below.

[0052] Table 1. Performance test results of the FRP pipelines prepared in Examples 1-5 and Comparative Examples 1-3

[0053] As can be seen from Examples 1-3, through the synergistic effect of the tetrafunctional organosilicon epoxy resin and the PEI / montmorillonite layer-by-layer self-assembly interface enhancement on the glass fiber surface, the fiberglass pipeline prepared has high circumferential tensile strength, axial compressive strength and extremely low H2 permeability, making it suitable for long-distance transportation of small molecule gases such as high-pressure hydrogen and natural gas.

[0054] As can be seen from Examples 4 and 5, based on Example 3, the addition of terminal epoxy allyl polyether can further improve the circumferential tensile strength and axial compressive strength of the pipe while maintaining low H2 permeability, thus achieving synergistic optimization of mechanical properties and barrier properties.

[0055] As can be seen from Examples 1 and Comparative Examples 1-3: Comparative Example 1 did not undergo PEI / montmorillonite layer-by-layer self-assembly modification on the glass fiber surface, resulting in weak bonding between the fiber and resin interface. Under high pressure, microcracks were easily generated, leading to easy permeation and diffusion of gas molecules along the fiber-resin interface, resulting in high hydrogen permeability. Comparative Example 2 did not add tetrafunctional organosilicon epoxy resin, resulting in insufficient density of the resin matrix and deterioration of intrinsic barrier properties. Comparative Example 3 directly incorporated organically modified montmorillonite into the resin matrix, making it difficult for the montmorillonite sheets to form a continuous and ordered nano-barrier structure.

Claims

1. A method for preparing a gas transmission fiberglass pipeline, characterized in that, Includes the following steps: S1: Preparation of epoxy resin solution: By weight, add 5-15 parts of organosilicon epoxy resin, 3-8 parts of hydroxyl-terminated hyperbranched polyester, 40-50 parts of methylhexahydrophthalic anhydride and 0.5-1.5 parts of curing accelerator to 100 parts of bisphenol A type epoxy resin, mix at 50-60℃, degas, and obtain epoxy resin solution. S2: Preparation of modified continuous glass fibers: (1) After heat treatment and etching, the glass fiber material is washed, sprayed with silane coupling agent pre-hydrolysis solution, and dried to obtain activated glass fiber; (2) The activated glass fiber is impregnated and dried in polyethyleneimine solution, and then impregnated and dried in organic modified montmorillonite dispersion to form one cycle; The cycle is repeated at least once to obtain modified continuous glass fibers; S3: Modified continuous glass fiber is impregnated in epoxy resin solution, and the amount of epoxy resin solution adhering is controlled to be 28%~33% of the mass of modified continuous glass fiber. It is then wound onto the inner lining pipe by a winding machine to form a pipe blank, and then cured in a gradient to obtain a fiberglass pipeline; the organosilicon epoxy resin is a tetrafunctional organosilicon epoxy resin.

2. The method for preparing a gas transmission fiberglass pipeline according to claim 1, characterized in that, The silane coupling agent used in the pre-hydrolyzed solution is selected from at least one of silane KH-560, silane KH-550, and silane KH-792.

3. The method for preparing a gas transmission fiberglass pipeline according to claim 1, characterized in that, The polyethyleneimine solution contains polyethyleneimine with a molecular weight of 600-1800 and a concentration of 5-15 g / L.

4. The method for preparing a gas transmission fiberglass pipeline according to claim 1, characterized in that, The concentration of the organically modified montmorillonite dispersion is 10~20 g / L.

5. The method for preparing a gas transmission fiberglass pipeline according to claim 4, characterized in that, The method for preparing the organically modified montmorillonite in the organically modified montmorillonite dispersion includes the following steps: Sodium-based montmorillonite was uniformly dispersed in water and heated to 60-80℃. Hexadecyltrimethylammonium bromide was added at 0.3-0.4 times the mass of sodium-based montmorillonite. The mixture was kept at a constant temperature and mixed for 2-4 hours. The solid and liquid were separated, washed, and sieved to obtain organically modified montmorillonite.

6. The method for preparing a gas transmission fiberglass pipeline according to claim 1, characterized in that, In step S2 (1), the heat treatment temperature is 380~420℃, the etching uses a nitric acid solution with a mass fraction of 5%~7%, and the etching time is 3~5min.

7. The method for preparing a gas transmission fiberglass pipeline according to claim 1, characterized in that, The inner lining tube is selected from polytetrafluoroethylene tubes or high-density polyethylene tubes.

8. The method for preparing a gas transmission fiberglass pipeline according to claim 1, characterized in that, In step S1, after adding the terminal hydroxyl hyperbranched polyester, the step further includes adding 5-7 parts by mass of terminal epoxy allyl polyether.

9. A gas-carrying fiberglass pipeline prepared by the preparation method according to any one of claims 1 to 8, for long-distance gas transportation.

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