A composite material pipeline for preventing hydrogen leakage

Abstract

The present invention provides a composite material pipeline for preventing hydrogen leakage, belonging to the technical field of pipeline preparation. The composite material pipeline includes an inner pipe layer, a composite gas barrier layer located on the outer surface of the inner pipe layer, a high-temperature resistant copolymer layer located on the outer surface of the composite gas barrier layer, a reinforcing layer located on the outer surface of the high-temperature resistant copolymer layer, and a corrosion-resistant polymer protective layer located on the outer surface of the reinforcing layer; the composite gas barrier layer is a multi-layer co-extrusion molding structure, and in the order from inside to outside, the composite gas barrier layer includes a blended and modified PVDC layer, a blended and modified EVOH layer, and a blended and modified PA layer. The composite material pipeline for preventing hydrogen leakage of the present invention, with its multi-layer composite structure, excellent material selection, and optimized production process, has excellent gas barrier performance, high strength, corrosion resistance, high temperature resistance, and good flexibility, etc., and can effectively solve the problems of hydrogen embrittlement, leakage, and corrosion faced by traditional steel pipes during hydrogen transportation, and has significant technical advantages and broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen transportation pipeline preparation, and particularly relates to a composite pipeline for preventing hydrogen leakage. Background Art

[0002] With the increasing importance of hydrogen as a clean energy source, technologies for hydrogen production, storage, transportation, and use are developing rapidly. The pipeline system for transporting hydrogen is a key link in the hydrogen industrial chain. Currently, most pure hydrogen transportation pipelines are made of steel. However, steel is prone to hydrogen embrittlement in a high-pressure hydrogen environment, that is, hydrogen molecules are decomposed into hydrogen atoms and penetrate into the interior of the steel, resulting in the degradation and embrittlement of the material's properties, and ultimately may lead to cracks and failures in the pipeline. Therefore, traditional carbon steel materials pose serious safety hazards in hydrogen transportation pipelines.

[0003] To overcome this problem, alloy steel materials are selectively used to improve the hydrogen embrittlement resistance of the pipeline. However, the cost of alloy steel is relatively high, and due to the lack of flexibility of steel, it is difficult to manufacture coiled pipes suitable for long-distance transportation and laying. In addition, steel pipes still require additional anti-corrosion coatings, which increase the laying and maintenance costs of the pipeline, and the construction process is complex and time-consuming.

[0004] On the other hand, some low-pressure hydrogen transportation applications have started to use plastic materials such as polyethylene or polyvinyl chloride as alternative materials. These plastic materials have hydrogen embrittlement resistance and corrosion resistance, but in high-pressure and high-temperature environments, the strength and heat resistance of plastic materials are poor, making it difficult to meet the requirements of high-pressure hydrogen transportation, and they are prone to leakage due to the penetration of high-pressure hydrogen. This limits their application in high-pressure hydrogen transportation pipelines.

[0005] Therefore, how to develop a composite pipeline that can solve the problem of hydrogen leakage while having good strength, high temperature resistance, and corrosion resistance is an urgent problem to be solved. Summary of the Invention

[0006] The purpose of the present invention is to address the above problems existing in the prior art and propose a composite pipeline for preventing hydrogen leakage.

[0007] The purpose of the present invention can be achieved by the following technical solutions: A composite pipeline for preventing hydrogen leakage, characterized in that the composite pipeline includes an inner pipe layer, a composite gas barrier layer located on the outer surface of the inner pipe layer, a high-temperature resistant copolymer layer located on the outer surface of the composite gas barrier layer, a reinforcing layer located on the outer surface of the high-temperature resistant copolymer layer, and a corrosion-resistant polymer protective layer located on the outer surface of the reinforcing layer; the composite gas barrier layer is a multi-layer co-extrusion molded structure, and in the order from the inside to the outside, the composite gas barrier layer includes a blended modified PVDC layer, a blended modified EVOH layer, and a blended modified PA layer.

[0008] The hierarchical design of the above composite material pipeline is set according to the following principles: Gas barrier performance: Through the multi-layer structure of the composite gas barrier layer, the combination of PVDC, EVOH and PA is used to gradually increase the gas barrier effect and ensure the effective isolation of hydrogen. High temperature resistance: The high temperature resistant copolymer layer effectively improves the stability of the pipeline in high temperature environments, avoiding material softening or performance degradation caused by high temperatures. Mechanical strength: The reinforcement layer provides the necessary physical strength to prevent the pipeline from being damaged by external impacts or pressures. Corrosion resistance: The corrosion resistant protective layer ensures the long-term use of the pipeline in harsh environments and avoids corrosion damage. This sequential setting aims to provide protection against hydrogen leakage, high temperature resistance, corrosion resistance and sufficient mechanical strength to ensure the safety and reliability of the pipeline during long-term use.

[0009] The composite gas barrier layer is a crucial part of the hydrogen leakage prevention composite material pipeline. Its function is to significantly improve the gas barrier performance of the pipeline through the synergistic effect of multiple layers of materials. This design is based on the following key factors: 1. Gradual enhancement of gas barrier performance: Hydrogen, as a very small and highly diffusible molecule, requires particularly strong materials to effectively block its penetration. The composite gas barrier layer uses a combination of multiple materials to achieve multiple gas barriers. The PVDC layer is located in the innermost layer and mainly plays a core gas barrier role. PVDC has excellent low gas permeability, especially strong resistance to hydrogen penetration. Therefore, it is the primary defense line of the composite gas barrier layer. PVDC resin itself can effectively reduce hydrogen leakage, but due to its physical properties (such as brittleness), its mechanical properties usually need to be enhanced. The EVOH layer is located outside the PVDC layer. EVOH has very good gas barrier performance, especially excellent in blocking gases such as hydrogen, oxygen, and carbon dioxide. Its main role is to enhance the gas barrier and make up for the deficiencies of the PVDC layer, especially more effective in the barrier effect on some smaller gas molecules. The structure of EVOH has good polarity, making it have higher adsorption and barrier properties for small molecule gases. The modified PA layer (modified polyamide) is located outside the EVOH layer. The addition of the PA layer is to further enhance the interlayer mechanical strength, and its main role is to improve the toughness and impact resistance of the material. PA resin usually has good chemical stability and physical strength, and through modification (adding polyvinyl alcohol and nano-montmorillonite), its adaptability to temperature and humidity and gas barrier performance can be improved. 2. Synergistic effect of different materials: Each layer of material has its unique performance advantages, and the design of the composite material makes full use of the characteristics of different materials so that they can complement each other and play the best effect. Synergistic effect of PVDC and EVOH: Both PVDC and EVOH have excellent gas barrier performance, but PVDC itself is relatively fragile and prone to cracking under external impact. In this case, EVOH can play a supporting role to improve the impact resistance of the entire gas barrier layer. By combining the PVDC and EVOH layers, their respective advantages can be exerted, reducing hydrogen penetration and improving the overall durability of the material. The modified PA layer not only helps to improve the impact resistance of the material but also helps to improve the adhesion between the inner and outer layers and prevent interlayer separation. 3. Processing and durability of materials: Interlayer interdependence: This layered design not only plays a multiple protection role in gas barrier performance but also takes into account the processing technology of each layer. The PVDC, EVOH, and PA layers can be prepared by coextrusion molding technology, so the complementarity and processing compatibility of materials need to be considered in the design. 4. Optimization of the design sequence: Setting the material layers in the order from the inside to the outside can enable hydrogen to be first blocked by the strongest gas barrier material (PVDC), then the barrier effect is further enhanced through the supplement of EVOH, and finally, through the enhancement and toughness improvement of the PA layer, it is ensured that the pipeline can be used under conditions such as high pressure and impact.

[0010] Preferably, in the blended and modified PVDC layer, nano-clay, a PVDC layer toughening agent, a PVDC layer cross-linking agent, and an antioxidant are added. The materials used are in a weight ratio of PVDC resin:nano-clay:PVDC layer toughening agent:PVDC layer cross-linking agent:antioxidant being 75-77:3-5:6-8:1-2:0.3-0.5; the PVDC layer toughening agent is polyethylene or polypropylene, and the PVDC layer cross-linking agent is specifically TBPB. The reasons for adding other materials to the PVDC layer are as follows: Addition of nano-clay: Function: By adding nano-clay to the PVDC layer, the mechanical strength, thermal stability, and barrier properties of PVDC can be significantly improved. The nano-clay particles are small in size and have a high surface area, which can fill the micro-pores of the PVDC layer, further reducing the hydrogen permeation channels. In addition, nano-clay can also improve the impact resistance and toughness of PVDC, preventing the material from cracking under high-pressure conditions. Use of the toughening agent (polyethylene or polypropylene): The addition of the toughening agent helps to improve the toughness of the PVDC layer and reduce its brittleness. Pure PVDC shows brittleness in some extreme environments, resulting in cracking or breakage under external forces, thus reducing its gas barrier performance. Polyethylene or polypropylene as the toughening agent has good processability and excellent weather resistance. Their introduction can enhance the flexibility of PVDC and reduce the risk of the pipeline cracking at low temperatures or under external forces. Therefore, the use of the toughening agent can improve the mechanical properties and durability of the PVDC layer, ensuring that the pipeline can withstand the leakage pressure of hydrogen and other gases for a long time. TBPB (tert-Butyl Peroxide) is an organic peroxide cross-linking agent that can promote the cross-linking reaction between PVDC molecular chains. The cross-linking agent can form a cross-linked structure between PVDC molecular chains, enhancing the mechanical strength and barrier properties. Through the cross-linking reaction, the thermal stability, antioxidant property, and mechanical strength of the PVDC material can be improved. In the composite pipeline, cross-linking can make the PVDC layer more stable under high-temperature conditions, avoiding problems such as aging and embrittlement during long-term use. Especially in a high-temperature environment, the cross-linking of PVDC molecular chains helps to enhance the stability of its structure, thereby improving the comprehensive performance of the composite material. The use of the TBPB cross-linking agent can ensure that the performance of the PVDC layer remains consistent at high temperatures, further enhancing its anti-aging and anti-degradation capabilities during high-temperature gas transportation. The addition of the antioxidant can effectively prevent the oxidation reaction from occurring during the long-term use of the PVDC layer. Oxidation will lead to a decline in the material's performance, especially the gas barrier property and toughness. Therefore, by adding an antioxidant, the long-term stability of the PVDC layer can be improved, ensuring the airtightness and structural integrity of the pipeline during long-term use. According to the given material ratio, the formulation of the PVDC layer achieves a balance among the components to ensure the optimization of the material's different properties.The ratio of PVDC resin : nano-clay : toughening agent : cross-linking agent : antioxidant is 75 - 77 : 3 - 5 : 6 - 8 : 1 - 2 : 0.3 - 0.5. This ratio is based on the following considerations: PVDC resin: As the main component, it has the largest proportion and is responsible for providing the basic properties of the PVDC layer, such as gas barrier properties. Selecting a ratio of 75 - 77% ensures the main structure of the material. Nano-clay: It has a relatively small proportion, but its improvement of gas barrier performance is very crucial. An appropriate amount of nano-clay can significantly enhance the gas barrier property and mechanical strength of the PVDC layer, while avoiding material embrittlement or processing difficulties caused by excessive use. Toughening agent and cross-linking agent: Appropriate amounts of toughening agent and cross-linking agent can effectively improve the toughness and durability of the material and enhance the pressure resistance performance of the pipeline. Hydrogen molecules are extremely small and can diffuse through almost all conventional materials. In order to effectively prevent hydrogen leakage, the PVDC layer must have excellent gas barrier properties. By adding the above components (such as nano-clay and cross-linking agent), the structure of the PVDC layer is strengthened and the gas barrier property is significantly improved.

[0011] Preferably, in the blend-modified EVOH layer, talcum powder, an EVOH layer crosslinking agent, and an antioxidant are added. The materials used are in a weight ratio of EVOH resin: talcum powder: EVOH layer crosslinking agent: antioxidant of 78 - 82:7 - 9:1.5 - 2:0.4 - 0.6; during the preparation of the EVOH layer, glycerol is added, and in a weight ratio, EVOH resin: glycerol is 100:3 - 5; the EVOH layer crosslinking agent is DCP. By adding glycerol as a plasticizer to the formulation, its flexibility can be increased. The addition of glycerol can reduce the brittleness of the EVOH layer, making it less likely to crack or deform when dealing with external pressure or environmental temperature changes, which is particularly important for pipes in long-term operation. Function: Flexibility: Increase the flexibility of the material and avoid cracks and leaks caused by thermal expansion or external force impact. Improve processability: The addition of glycerol also helps to improve the fluidity and molding effect of the EVOH layer during the manufacturing process, making the coextrusion molding process smoother. The addition amount of glycerol needs to be controlled within a relatively low range to maintain the barrier performance and strength of the EVOH layer. Excessive glycerol will reduce the rigidity of the material and affect the gas barrier ability. The dosage of 3 - 5 is to improve flexibility and processability while not damaging other properties. Setting the proportions of the various materials in the EVOH layer (the weight ratio of EVOH resin: talcum powder: EVOH layer crosslinking agent: antioxidant is 78 - 82:7 - 9:1.5 - 2:0.4 - 0.6) is based on the following considerations: 1. EVOH resin: Ensure gas barrier performance: EVOH resin is the core material of this layer, mainly responsible for gas barrier properties, especially the barrier of hydrogen. The molecular structure of EVOH itself gives it a strong gas barrier ability. However, the mechanical strength of EVOH resin is relatively weak, and the addition of other materials is required to enhance its structural properties. Therefore, EVOH resin occupies a dominant position in this ratio, which ensures the gas barrier performance of the material while avoiding problems of softness and brittleness caused by excessive resin content. 2. Talcum powder: Talcum powder, as an inorganic filler, has the effect of improving mechanical properties. Its addition can effectively increase the hardness, tensile strength, and compressive strength of the EVOH layer. The addition of talcum powder also helps to reduce the cost of EVOH and avoid over-reliance on high-cost EVOH resin. The dosage of talcum powder is between 7 - 9, ensuring enhanced rigidity without overly weakening the flexibility and heat resistance of the material. 3. EVOH layer crosslinking agent: Reasons for using DCP as the EVOH layer crosslinking agent: DCP (dicumyl peroxide) is used as a crosslinking agent in the EVOH layer for a specific purpose: Crosslinking effect: DCP is a typical organic peroxide crosslinking agent, and it can form chemical crosslinks between polymer chains through a free radical mechanism. EVOH is a material with good gas barrier properties, but its mechanical strength and heat resistance are relatively limited.Using DCP as a crosslinking agent can initiate a crosslinking reaction to establish stronger chemical bonds between the molecular chains of EVOH, significantly improving the heat resistance, mechanical strength, chemical corrosion resistance and other properties of EVOH. This is crucial for pipelines that prevent hydrogen leakage because crosslinked EVOH can maintain its gas barrier properties for a longer time, especially in high-temperature and long-term use environments. Temperature stability: The crosslinked EVOH layer can still maintain good physical properties in high-temperature environments. DCP can effectively initiate the crosslinking reaction at a relatively low decomposition temperature, which is suitable for matching the processing temperature of EVOH. The crosslinked EVOH can not only withstand higher operating temperatures but also improve its antioxidant properties. Hydrogen gas permeability resistance: EVOH itself has good gas barrier properties, but after crosslinking, its molecular structure becomes more compact, reducing the penetration rate of hydrogen molecules in the material. Therefore, the use of DCP crosslinking agent is to further improve the effect of preventing hydrogen leakage. The dosage of the crosslinking agent in the EVOH layer is between 1.5 and 2. An appropriate amount of crosslinking agent can improve the stability of the EVOH layer in long-term high-temperature and oxidative environments, but excessive use will increase the brittleness of the material. Therefore, the ratio of 1.5 - 2 is to achieve a balance between good thermal stability and durability. 4. Antioxidant: In this formulation, the ratio of the antioxidant in the EVOH layer: The choice of antioxidant needs to effectively prevent oxidation without overly affecting other properties of the material. Selecting this ratio can effectively inhibit the oxidative degradation of the EVOH resin and maintain the stability of the material. By optimizing the ratios of these materials, the EVOH layer of the composite pipeline can maintain high-efficiency barrier properties during long-term use, prevent hydrogen leakage, and at the same time have good mechanical properties and environmental adaptability.

[0012] Preferably, in the blend-modified PA layer, polyvinyl alcohol, nano-montmorillonite, PA layer plasticizer, and antioxidant are added. The materials used are in a weight ratio of PA resin: polyvinyl alcohol: nano-montmorillonite: PA layer plasticizer: antioxidant = 100: 2.5 - 3: 3 - 5: 1.5 - 2.5: 0.4 - 0.6; the PA layer plasticizer is TPP. Setting this ratio (PA resin: polyvinyl alcohol: nano-montmorillonite: modified PA layer plasticizer: antioxidant = 100: 2.5 - 3: 3 - 5: 1.5 - 2.5: 0.4 - 0.6) is based on the following considerations: 1. PA resin: Guarantee of basic properties: PA resin dominates in the modified PA layer and is mainly responsible for the basic mechanical properties and gas barrier properties of this layer. Polyamide materials have good toughness and wear resistance, but in the face of extreme environments, there are problems such as moisture absorption and insufficient thermal stability. Therefore, the proportion of PA resin is usually set at 100 parts to ensure that its basic role in the entire modified layer is not weakened. 2. Polyvinyl alcohol: Improvement of processability and water resistance: The role of polyvinyl alcohol in the modified PA layer is to improve its processability, enhance water resistance, and increase the barrier ability to hydrogen. PVA is a water-soluble polymer material that can improve the moisture absorption performance of polyamide, prevent thermal degradation caused by moisture, and enhance the adhesion and thermal stability of the material. The addition ratio is set at 2.5 - 3, which can not only improve the performance of the layer but also avoid embrittlement of the material caused by excessive addition. 3. Nano-montmorillonite: Enhancement of structural properties and thermal stability: Nano-montmorillonite is a layered silicate mineral with a very high specific surface area and good mechanical properties, which can effectively enhance the structural properties of polymers. Its addition can improve the anti-permeability, antioxidant property, and high-temperature resistance of the PA layer, and at the same time, it can also improve the impact resistance and compressive strength of the composite material. The dosage of nano-montmorillonite can ensure the enhancement effect of the material without introducing too many impurities to affect other properties. 4. Plasticizer: The main function of the plasticizer is to lower the glass transition temperature (Tg) of the polymer, making the material more flexible and processable. In the composite material pipeline, the plasticizer can enhance the mechanical properties and toughness of the modified PA layer, making the pipeline more durable, especially in complex working environments, where high ductility and crack resistance are required. The selection of TPP (triphenyl phosphate) as the plasticizer has relatively special advantages in the polyamide (PA) system. TPP has good plasticizing effects. It can effectively reduce the rigidity of the polymer, improve its tensile property, impact resistance, and low-temperature toughness, making the modified PA layer more tough and not easy to crack under stress or low-temperature environments. Chemical resistance and environmental adaptability of TPP: TPP is a relatively common phosphate plasticizer with good high-temperature resistance, chemical stability, and anti-aging performance. In the composite material pipeline for preventing hydrogen leakage, TPP can provide enhanced chemical stability, especially under complex environmental conditions, effectively preventing the volatilization or degradation of the plasticizer, thereby extending the service life of the pipeline.Since hydrogen pipelines may experience extreme chemical environments or temperature changes, the heat resistance and antioxidant properties of TPP can ensure the stability of the modified PA layer during long-term exposure to these environments, maintaining its mechanical properties and the effectiveness of preventing hydrogen leakage. Low volatility and environmental friendliness of TPP: As a plasticizer, triphenyl phosphate (TPP) has low volatility as one of its prominent characteristics in addition to its common performance advantages. During the long-term use of the pipeline, the volatility of the plasticizer affects the comprehensive performance of the pipeline. The low volatility of TPP helps reduce the loss of the plasticizer, avoiding the embrittlement of the polymer caused by premature volatilization of the plasticizer, enabling the pipeline to maintain flexibility and crack resistance for a long time. In addition, TPP has better environmental friendliness compared to some traditional plasticizers (such as phthalate plasticizers) and meets the requirements of some environmental protection regulations. In modern material development, environmental friendliness and low volatility have become important criteria for material selection. Improving the functionality and processability of the PA layer: The use of TPP can also improve the processability of the PA (polyamide) layer. For example, it reduces the viscosity of the material at high temperatures during the manufacturing process, making it easier to form. For high-performance composite pipelines, this helps better control the forming of materials during production, obtaining excellent interfacial bonding and overall structural stability. Enhancing the comprehensive performance of the pipeline: As a plasticizer, TPP can improve the toughness and fatigue resistance of the modified PA layer, reducing the generation and propagation of cracks in stress concentration areas or under long-term cyclic loads. In the application of pipelines for preventing hydrogen leakage, the selection of plasticizer is directly related to the stability and performance maintenance of the pipeline during long-term use, especially under high pressure and complex temperature changes. The purpose of using the plasticizer TPP is to improve the flexibility, chemical resistance, anti-aging property of the modified PA layer, increase the processability of the material, and at the same time extend the service life and stability of the composite pipeline. Its low volatility and good environmental performance are also one of the reasons for its ideal choice. Antioxidant: Extending the service life: The role of the antioxidant in the modified PA layer is to prevent oxidative degradation in high-temperature environments, thereby extending the service life of the material. This proportion of the antioxidant ensures that the material can maintain good stability during long-term use. Comprehensive analysis: By reasonably setting the proportions of these components, the performance of the modified PA layer is optimized, ensuring that the composite pipeline has good hydrogen barrier properties, mechanical strength, corrosion resistance, and long-term stability. Specifically: PA resin provides the basic mechanical strength and wear resistance. Polyvinyl alcohol improves water resistance and processability and enhances the barrier property. Nanometer montmorillonite enhances the strength, high-temperature resistance, and impermeability of the material. The plasticizer improves the flexibility and processability of the material, avoiding brittleness problems. The antioxidant enhances the heat and oxidation resistance of the material and extends the service life. Through this ratio design, the modified PA layer can provide good gas barrier effects in pipelines for preventing hydrogen leakage, while having sufficient mechanical strength and long-term durability.

[0013] Preferably, the composite material used in the reinforcement layer is prepared by vacuum-assisted resin transfer molding, and the materials used are in a weight ratio of carbon fiber: epoxy resin: amorphous nano-silica of 60-70:30-40:5-8. The reinforcement layer is prepared by vacuum-assisted resin transfer molding, and the choice of setting the ratio has its own unique engineering design and performance requirements. 1. Why vacuum-assisted resin transfer molding is used to prepare the reinforcement layer: Vacuum-assisted resin transfer molding is a molding process used in composite material manufacturing. There are several key reasons for choosing this method: Improve the density and structural strength of the composite material: The VARTM process places a dry fiber preformed structure in a mold and guides the resin into the fiber by vacuum suction, which helps to efficiently fill the gaps between the fibers and ensure uniform distribution of the resin. This method can achieve a higher fiber volume ratio, thereby improving the strength, stiffness and impact resistance of the reinforcement layer. Reduce bubbles and uneven distribution of resin: The auxiliary effect of the vacuum helps to eliminate possible bubbles or uneven resin distribution, improve the density and reliability of the composite material, and avoid the generation of weaknesses. This is particularly important for structures such as pipelines that are subject to pressure and stress, especially in applications to prevent hydrogen leakage, where the airtightness and strength of the material are crucial. Suitable for the combination of high-performance materials: Provide better fiber / resin bonding, thereby enhancing the mechanical properties, corrosion resistance, etc. of the composite material. 2. Set the ratio of carbon fiber, epoxy resin and amorphous nano-silica as follows: The ratio of carbon fiber is high (60-70): Strengthen the mechanical properties of the material: Carbon fiber, as a high-strength and high-rigidity reinforcement material, can greatly improve the tensile strength, compressive strength and bending resistance of the composite material. The reinforcement layer needs to bear pressure and external stress, so a high ratio of carbon fiber can provide sufficient mechanical properties to ensure the structural integrity and deformation resistance of the pipeline. Improve thermal conductivity: The thermal conductivity of carbon fiber can also help the composite material dissipate heat better in a high-temperature environment to avoid local overheating or thermal deformation. The ratio of epoxy resin is low (30-40): The role of the resin is to bond and solidify the fiber: Epoxy resin not only acts as a binder to bind the carbon fibers together, but also plays a curing role to ensure the structural stability of the entire reinforcement layer. The relatively low proportion of epoxy resin is because the resin mainly plays a fixing and filling role, and too much resin will increase the weight of the material and reduce the mechanical properties. High temperature and chemical resistance of the resin: Epoxy resin has good high temperature resistance and corrosion resistance. While strengthening the composite material, it can adapt to the requirements of high temperature and chemical corrosion environment. The proportion of amorphous nano-silica is low (5-8): Enhanced resin performance: The addition of amorphous nano-silica is intended to improve the mechanical properties, thermal stability and wear resistance of the resin. Nano-silica has a strong reinforcing effect and can fill the tiny gaps in epoxy resin, improving its compressive strength, shear strength and heat resistance.Improve fluidity and curing process: Nano-silica can improve the fluidity of the resin, making it more uniform when injected into the mold, thus improving the quality of the finished product. 3. Summarize the purpose of ratio selection: Balance of comprehensive properties: A high proportion of carbon fiber provides strength, stiffness, and thermal conductivity, suitable for withstanding high pressures, avoiding deformation and crack propagation. Epoxy resin plays a role in connecting and fixing the carbon fiber, but the proportion is relatively low to avoid excessive resin reducing the overall mechanical properties. The appropriate use of amorphous nano-silica enhances the high-temperature resistance and corrosion resistance of the resin, while also improving the stability and processability of the overall material. Performance requirements for preventing hydrogen leakage: Through this optimized ratio combination of the composite reinforcement layer, excellent mechanical properties, airtightness, high-temperature resistance, and corrosion resistance can be provided, thus meeting the special requirements for preventing hydrogen leakage. Through vacuum-assisted resin transfer molding, the high strength, uniformity, and durability of the composite material can be ensured. In the ratio design of the reinforcement layer, the selection and ratio adjustment of carbon fiber, epoxy resin, and nano-silica are based on the comprehensive performance requirements of the material, aiming to maximize its mechanical properties, heat resistance, corrosion resistance, and processing performance, ensuring that the pipeline can effectively prevent hydrogen leakage and maintain long-term stability in harsh environments.

[0014] Preferably, the material of the inner tube layer is one of RTP and TCP. Selecting one of the materials of reinforced thermoplastic pipe (RTP) and thermoplastic composite pipe (TCP) as the inner tube layer is mainly based on the following comprehensive performance requirements and material property analysis:

[0015] 1. Excellent gas barrier performance: Requirement: Preventing hydrogen permeation is a key objective. As the first barrier, the inner tube layer needs to have extremely low hydrogen permeability. Advantages of RTP / TCP: Both RTP and TCP have low gas permeability. Especially when combined with reinforcing fibers and multi-layer composite design in the structure, the possibility of hydrogen leakage can be significantly reduced. 2. Mechanical strength and pressure resistance performance: Requirement: Hydrogen transportation is usually carried out under high-pressure environments, requiring the inner tube layer to have sufficient mechanical strength, anti-deformation ability, and high-pressure resistance. RTP / TCP can withstand high working pressures. 3. Chemical corrosion resistance: Requirement: Hydrogen transportation pipelines need to face certain chemical corrosion environments, requiring the inner tube layer material to be stable and corrosion-resistant. The thermoplastic matrix material itself has good chemical corrosion resistance and can resist the erosion of hydrogen during long-term use. The thermoplastic composite material used in TCP also has excellent acid-base resistance and chemical stability, especially suitable for complex chemical environments. 4. Temperature adaptability: Requirement: The pipeline may operate in high-temperature or low-temperature environments, and the material needs to adapt to temperature differences without failure. Advantages of RTP / TCP: RTP can adapt to a wide temperature range. The matrix material of TCP shows better high-temperature stability and can be used for a long time under harsh high-temperature conditions. 5. Manufacturability and economy: Requirement: The material needs to be easy to process and have an acceptable cost. Advantages of RTP / TCP: RTP uses a thermoplastic matrix, and the manufacturing process is relatively simple and the cost is low, suitable for large-scale industrial applications. The manufacturing process of TCP is more complex, but its high performance makes it more cost-effective under more demanding conditions (such as high-pressure, large-flow hydrogen transportation). 6. Compatibility with the composite gas barrier layer: Requirement: The inner tube layer and the composite gas barrier layer (PVDC, EVOH, PA, etc.) need to have good interfacial bonding to ensure the integrity and durability of the composite pipeline. Comprehensive analysis: Comprehensive performance: Both RTP and TCP have high strength, low permeability, chemical corrosion resistance, and good temperature adaptability. Mature technology: The manufacturing technologies of RTP and TCP have been widely used in high-pressure oil and gas transportation, with high reliability. Economic feasibility: RTP is more suitable for large-scale, standard application scenarios, while TCP is suitable for high-end scenarios with more demanding performance requirements. Recommended application scenarios: RTP (Reinforced Thermoplastic Pipe): Suitable for medium and low-pressure hydrogen transportation, or applications in cost-sensitive projects. TCP (Thermoplastic Composite Pipe): Suitable for high-pressure or extreme environment hydrogen transportation, especially under high-temperature or corrosive conditions.

[0016] Preferably, the material used for the high-temperature resistant copolymer layer is polyimide. Polyimide can maintain stable properties at very high temperatures, usually with a temperature range of -200°C to 400°C that it can withstand. This high-temperature stability makes it an ideal material for handling high-temperature environments, especially suitable for pipe systems with large temperature variations. Mechanical strength and toughness: Polyimide has excellent tensile strength, hardness, and impact resistance, which can effectively prevent the deformation and fracture of the pipe in a high-temperature environment. Chemical stability: Polyimide has very strong corrosion resistance to most chemicals (including strong acids, strong bases, solvents, etc.) and can be used for a long time in a harsh chemical environment. This is crucial for hydrogen leakage prevention pipes because hydrogen and certain corrosive substances may come into contact with the pipe, requiring the pipe material to have strong corrosion resistance. Electrical properties: Polyimide has good electrical insulation properties. Due to its extremely high heat resistance and good chemical stability, polyimide as a high-temperature resistant copolymer layer material can effectively protect the composite pipe from damage due to thermal expansion and contraction in a high-temperature environment, and at the same time can effectively prevent the leakage of corrosive substances such as hydrogen. In the design of composite pipes for hydrogen leakage prevention, polyimide can provide the necessary temperature and chemical corrosion resistance, ensure the long-term reliability of the pipe, has good processing performance, can be successfully formed and processed during the pipe manufacturing process, and meets the requirements of complex pipe designs.

[0017] Preferably, the material used for the corrosion-resistant polymer protective layer is polytetrafluoroethylene or fluorinated ethylene-propylene copolymer. In the composite pipeline for preventing hydrogen leakage, choosing polytetrafluoroethylene (PTFE) or fluorinated ethylene-propylene copolymer (FEP) as the material for the corrosion-resistant polymer protective layer is mainly based on their excellent chemical stability and corrosion resistance. The following is a detailed analysis of the reasons: Polytetrafluoroethylene: Main characteristics: Excellent corrosion resistance: PTFE has almost complete chemical inertness and has extremely strong tolerance to most corrosive substances such as acid, alkali, salt solutions, solvents, and oxidizing gases. PTFE has a low coefficient of friction, which can effectively reduce friction and wear and is suitable for application scenarios with fluid flow in pipeline systems. Anti-aging and stability: PTFE is not easily aged by environmental factors such as ultraviolet rays and oxidation and can be used stably for a long time. Hydrogen has strong permeability and reactivity. The extremely high chemical stability and corrosion resistance of PTFE enable it to effectively prevent hydrogen from reacting with the pipeline surface or leaking. In addition, the high-temperature resistance and anti-oxidation characteristics of PTFE make it an ideal choice that can still maintain performance in high-temperature environments, especially crucial in the pipeline protective layer for preventing hydrogen leakage. Fluorinated ethylene-propylene copolymer (FEP): Copolymerized from ethylene and tetrafluoroethylene, it has similar properties to PTFE but is relatively easier to process and form. Main characteristics: Excellent chemical stability: FEP has extremely strong corrosion resistance to most chemical substances, especially acids, alkalis, solvents, and hydrogen, and can effectively prevent hydrogen from permeating or leaking. Compared with PTFE, FEP has better processability and can be processed by traditional thermoplastic forming methods (such as injection molding, extrusion, etc.), which is of great significance for large-scale production of pipelines for preventing hydrogen leakage. Transparency: FEP has good transparency, which may provide additional visual inspection convenience in some applications, especially in pipeline monitoring systems. FEP is similar to PTFE in terms of corrosion resistance and high-temperature resistance and has excellent processability, making it a favorable choice in pipeline protective layers. Choosing PTFE or FEP as the material for the corrosion-resistant polymer protective layer is based on the following points: Corrosion resistance: The reactivity of hydrogen makes the pipeline material need to have extremely strong chemical stability, especially in a more corrosive environment. Both PTFE and FEP can provide extremely strong corrosion resistance to ensure that hydrogen does not permeate or react with the pipeline. High-temperature resistance performance: Hydrogen pipelines may face high-temperature environments in industry, which requires the pipeline protective layer to have high-temperature stability. PTFE has very strong high-temperature resistance, and FEP can also meet the temperature requirements in most industrial applications. Processability: FEP has better processability and is easier to process and form compared to PTFE, especially more convenient in pipeline protective layers that require complex shapes. Long-term stability: Both PTFE and FEP have anti-oxidation and anti-aging characteristics and can maintain excellent performance during long-term use, preventing the pipeline protective layer from degrading due to environmental factors.Therefore, choosing PTFE or FEP as the corrosion-resistant protective layer can ensure the reliability and stability of the pipeline during long-term use, especially providing necessary protection in high-temperature and hydrogen leakage environments to ensure the best anti-leakage effect.

[0018] Preferably, the reinforcing layer adopts a multi-layer intertwined fiber structure. The laying direction of each layer of fiber is 0° / 90° or ±45°, the number of layers is 3 - 7 layers, and at least one layer adopts ±45°; a temperature-controlled curing box is used during the curing process of the reinforcing layer, and the temperature inside the curing box is set to 130°C to 150°C; a modified polyamine curing agent is selected as the curing agent for epoxy resin, and the curing time is 2 - 4 hours.

[0019] 1. Necessity of the multi-layer intertwined fiber structure: This design ensures that the pipeline has sufficient tensile strength, shear strength, and impact resistance. Laying direction of the multi-layer intertwined fibers: 0° / 90° laying: The fibers in the 0° direction provide axial strength, making the pipeline not easily stretched and deformed under the action of hydrogen internal pressure. The fibers in the 90° direction provide circumferential strength to avoid circumferential cracking or deformation caused by internal pressure. ±45° laying: The fibers in the ±45° direction increase the shear strength of the pipeline, improve the torsional resistance, and can cope with bending, lateral loads, or complex external forces. The ±45° layer can also effectively disperse local stress and prevent structural damage caused by stress concentration. 3 - 7 layers: The multi-layer structure can significantly improve the overall rigidity and strength of the composite material, making the pipeline suitable for high-pressure hydrogen transmission requirements while controlling material costs and weight. At least one layer of ±45°: By increasing the fiber layer in the ±45° direction, the strength limitations of 0° / 90° laying can be compensated, and the overall stability of the pipeline under multi-directional stress conditions can be improved.

[0020] 2. Setting of the curing process: The temperature of the temperature-controlled curing oven is set to 130°C to 150°C. The curing temperature is a key parameter for the curing reaction of epoxy resin. Too low temperature: The curing rate is slow, resulting in incomplete curing of the material, reducing mechanical properties and durability. Too high temperature: It causes thermal stress or poor interfacial bonding between the reinforcing fiber / resin. 130°C to 150°C: This temperature range is an optimized temperature interval commonly used in the epoxy resin system, which can ensure complete curing of the reinforcing layer, thus maximizing mechanical properties and high-temperature resistance. Select modified polyamine curing agent as the epoxy resin curing agent: Advantages of modified polyamine: Moderate reaction rate: It can provide a suitable curing rate within the range of 130°C to 150°C, ensuring uniform curing of the internal structure of the composite material. High toughness: The modified polyamine curing agent can endow the cured epoxy resin with higher toughness and impact resistance, making the pipeline reinforcing layer more durable. Thermal aging resistance: The epoxy resin cured by modified polyamine can withstand higher temperatures, improving the thermal stability of the pipeline. The curing time is set to 2 - 4 hours: The curing time needs to find a balance between strength growth and production efficiency. Too short time: Curing may be incomplete, affecting the mechanical properties and structural stability of the reinforcing layer. Too long time: It will reduce production efficiency and increase manufacturing costs. 2 - 4 hours: In a temperature-controlled environment of 130°C to 150°C, 2 - 4 hours can achieve complete curing of the epoxy resin, ensuring that the reinforcing layer reaches the ideal mechanical properties and thermal stability. The purpose of the above settings is to optimize the structure and processing technology of the reinforcing layer, enabling it to have the following properties: High strength and pressure resistance: The multi-layer fiber interwoven structure enables the reinforcing layer to withstand the internal and external pressures of the hydrogen pipeline. Shear resistance and torsional resistance: The ±45° ply significantly improves the stability of the reinforcing layer under complex stress conditions. Thermal stability and chemical stability: Through the temperature-controlled curing process and modified polyamine curing agent, it is ensured that the reinforcing layer can operate stably for a long time in high-temperature and corrosive environments. Efficient production and reliability: The reasonable setting of curing time and temperature improves production efficiency while ensuring performance. The setting of the above parameters is to achieve a balance among mechanical properties, thermal properties and production efficiency, ensuring that the reinforcing layer of the composite material pipeline can meet the high-strength, high-stability and long-life requirements for hydrogen transmission, and at the same time making the production process have good feasibility and economy. These design details are crucial for the safety and reliability of the hydrogen pipeline.

[0021] Regarding the carbon fiber used, the parameters are as follows: Type: Use long fibers or continuous fibers, with high strength and low density, improving the tensile strength and rigidity of the pipeline. Fiber diameter: 5 - 10 μm; Tensile strength: 3000 - 7000 MPa; Modulus: 200 - 800 GPa

[0022] Preferably, the antioxidant used is Irganox 1010 antioxidant or BHT antioxidant.

[0023] The present invention proposes a composite material pipeline for preventing hydrogen leakage. Its structural design integrates functional materials at multiple levels to address various challenges faced by hydrogen transmission pipelines, especially the problem of hydrogen leakage. The following are the beneficial effects of the present invention: 1. Effectively prevent hydrogen leakage: The multi-layer structure design of the inner pipe layer, composite gas barrier layer, high-temperature copolymer layer, reinforcement layer, and corrosion-resistant polymer protective layer of this composite material pipeline can effectively isolate the contact between hydrogen and the external environment, reduce the penetration and leakage of hydrogen, ensure the airtightness of the pipeline over a long period of time, and meet the safety requirements for high-pressure hydrogen transmission. In particular, the composite gas barrier layer uses a multi-layer co-extrusion molding structure, which is composed of a modified PVDC layer, an EVOH layer, and a PA layer in sequence. The interaction of the three layers significantly improves the gas barrier effect.

[0024] 2. Improve the strength and high-temperature resistance of the pipeline: In a high-temperature environment, the high-temperature copolymer layer (polyimide) of the pipeline can effectively resist the damage of the thermal environment to the pipeline material and extend the service life of the pipeline. The reinforcement layer is prepared by the vacuum-assisted resin transfer molding (VARTM) method, combining a composite material of carbon fiber, epoxy resin, and nano-silica, which significantly enhances the strength and pressure resistance of the pipeline, enabling it to operate stably under high pressure and harsh environments for a long time.

[0025] 3. Reduce the risk of hydrogen embrittlement and corrosion: Traditional steel pipes are prone to hydrogen embrittlement in a high-pressure hydrogen environment, leading to pipeline cracking and failure. However, in the composite material pipeline of the present invention, a corrosion-resistant polymer protective layer (such as polytetrafluoroethylene or fluorinated ethylene-propylene copolymer) is used, which can effectively prevent the erosion of corrosive media and avoid the failure of metal materials caused by corrosion or hydrogen embrittlement.

[0026] 4. Improve the flexibility and operability of the pipeline: The composite material pipeline is more flexible than traditional steel pipes, with strong adaptability. It can be manufactured in long strip or coil forms, which is convenient for transportation, laying, and installation. This design helps to simplify the construction process of the hydrogen transmission pipeline, reduce the labor and equipment costs during construction, and improve the construction efficiency.

[0027] 5. Reduce the pipeline weight and save material costs: The composite material pipeline is lighter in weight than traditional steel pipes and has lower material costs. By using lightweight plastic materials such as polyethylene and polyvinyl chloride, combined with composite materials with higher strength, both the production and transportation costs are reduced, and the safety and long-term stability of the pipeline in high-pressure hydrogen transmission are ensured.

[0028] 6. Material optimization to improve antioxidant and anti-aging properties: Antioxidants and cross-linking agents are added to the composite material to improve the antioxidant and anti-aging properties of the pipeline material, prevent material degradation caused by oxidation, thereby extending the service life of the pipeline, and ensuring that it will not leak due to problems such as aging and oxidation during long-term use.

[0029] 7. Strong adaptability to meet different hydrogen transportation requirements: The composite material pipeline of the present invention can flexibly select the inner pipe layer materials (such as RTP and TCP) according to the requirements of specific applications, adapt to different hydrogen transportation environments, and can not only meet the conventional low-pressure hydrogen transportation requirements, but also handle the transportation tasks under higher pressure or high-temperature environments, showing wide applicability.

[0030] 8. Optimized design of the reinforcement layer structure: The reinforcement layer adopts a multi-layer interwoven fiber structure and a temperature-controlled curing process to ensure the strength and stability of the pipeline under pressure and temperature changes. The fiber layout in different directions (such as 0° / 90° or ±45°) enhances the tensile strength and compressive performance of the pipeline, ensuring good performance in complex environments.

[0031] In summary, the hydrogen leakage-proof composite material pipeline of the present invention, with its multi-layer composite structure, excellent material selection, and optimized production process, has excellent gas barrier performance, high strength, corrosion resistance, high temperature resistance, and good flexibility, etc. It can effectively solve the problems of hydrogen embrittlement, leakage, and corrosion faced by traditional steel pipes during hydrogen transportation, showing significant technical advantages and broad application prospects. Specific implementation manners

[0032] The following are specific embodiments of the present invention, which further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments. Specific embodiments

[0033] A hydrogen leakage-proof composite material pipeline, the composite material pipeline includes an inner pipe layer, a composite gas barrier layer located on the outer surface of the inner pipe layer, a high-temperature resistant copolymer layer located on the outer surface of the composite gas barrier layer, a reinforcement layer located on the outer surface of the high-temperature resistant copolymer layer, and a corrosion-resistant polymer protective layer located on the outer surface of the reinforcement layer; the composite gas barrier layer is a multi-layer co-extrusion molding structure, and in the order from the inside to the outside, the composite gas barrier layer includes a blended and modified PVDC layer, a blended and modified EVOH layer, and a blended and modified PA layer. The thickness parameters are as follows: inner pipe layer: 3.0 mm, high-temperature resistant copolymer layer: 0.3 mm, reinforcement layer: 2.0 mm, corrosion-resistant polymer protective layer: 0.3 mm.

[0034] In the blended and modified PVDC layer, nano-clay, a PVDC layer toughening agent, a PVDC layer cross-linking agent, and an antioxidant are added. The materials used are in a weight ratio of PVDC resin: nano-clay: PVDC layer toughening agent: PVDC layer cross-linking agent: antioxidant = 76:4:7:1.5:0.4; the PVDC layer toughening agent is polyethylene, and the PVDC layer cross-linking agent is specifically TBPB.

[0035] In the blended and modified EVOH layer, talcum powder, an EVOH layer crosslinking agent, and an antioxidant are added. The materials used are in a weight ratio of EVOH resin: talcum powder: EVOH layer crosslinking agent: antioxidant of 80:8:1.8:0.5; during the preparation of the EVOH layer, glycerol is added, and in a weight ratio, EVOH resin: glycerol is 100:4; the EVOH layer crosslinking agent is DCP.

[0036] In the blended and modified PA layer, polyvinyl alcohol, nano-montmorillonite, a PA layer plasticizer, and an antioxidant are added. The materials used are in a weight ratio of PA resin: polyvinyl alcohol: nano-montmorillonite: PA layer plasticizer: antioxidant of 100:3:4:2:0.5; the PA layer plasticizer is TPP.

[0037] During coextrusion, the binder is extruded between each layer to ensure good adhesion between each layer.

[0038] The reinforcing layer is prepared by the vacuum-assisted resin transfer molding method. The materials used are in a weight ratio of carbon fiber: epoxy resin: amorphous nano-silica of 70:35:6. The reinforcing layer adopts a multi-layer interwoven fiber structure, and the laying directions of the fibers in each layer are 0° / 90° and ±45°, with 5 layers in total, and two layers are ±45°. The specific process is as follows: Preparation: Cleaning and surface treatment: Ensure that the surface of the high-temperature resistant copolymer layer is free of contaminants such as dust and oil. Industrial cleaners can be used for wiping, and mild surface sanding (such as using fine sandpaper) can be carried out to increase the surface roughness and enhance the bonding performance. After cleaning, secondary cleaning is carried out using high-purity ethanol or acetone to thoroughly remove residues. Binder coating: Select a binder compatible with epoxy resin and evenly coat a layer of binder on the surface of the high-temperature resistant copolymer layer. The role of the binder is to enhance the adhesion between the high-temperature resistant copolymer layer and the reinforcing layer. Let the binder stand until the surface becomes slightly sticky (usually 15 - 30 minutes). 2. Preparation of the reinforcing layer: The reinforcing layer is directly formed on the outer surface of the copolymer layer through the vacuum-assisted resin transfer molding (VARTM) process. 2.1 Laying of the carbon fiber layer: Selection of carbon fiber material: According to the design, high-strength carbon fiber fabric is selected, with a multi-layer interwoven structure, and the laying directions are 0° / 90° and ±45°, with a total of 5 layers, and the middle two layers are ±45°. Laying of the carbon fiber layer: Lay the first layer of carbon fiber directly on the surface of the high-temperature resistant copolymer layer, and lay the subsequent layers in sequence. When laying each layer, ensure that the carbon fiber fabric is flat and free of wrinkles, and at the same time avoid entrapment of air. 2.2 Resin mixing and injection: Resin formulation: Disperse amorphous nano-silica into epoxy resin according to the weight ratio of epoxy resin: amorphous nano-silica = 35:6, and stir evenly. Add a modified polyamine curing agent, fully stir, and then carry out vacuum degassing to remove the bubbles generated during the mixing process. Vacuum-assisted injection: Cover the surface of the laid carbon fiber layer with a separation film, a flow guide net, and a vacuum bag film. Use a sealant strip to seal the vacuum environment, and connect a vacuum pump and a resin injection device through a pipeline. Set the vacuum pressure to -0.8 to -0.9 bar, and inject epoxy resin into the carbon fiber layer through an injection pressure of 0.1 - 0.2 MPa to make it fully penetrate. 2.3 Curing treatment: Curing: With the vacuum bag kept closed, place the entire pipeline into a temperature-controlled curing oven, set the curing temperature to 140°C, and the curing time to 3 hours. Precautions: Binder selection and coating: Use a binder compatible with epoxy resin and the copolymer layer, such as an amine-containing binder or an epoxy-modified binder, to ensure firm bonding between the layers. Vacuum process quality control: Ensure that the vacuum bag is well sealed, and there are no air bubbles remaining during the injection process to prevent problems such as voids or insufficient strength in the reinforcing layer.

[0039] The material of the inner tube layer is a reinforced thermoplastic plastic pipe, and the material used for the high-temperature resistant copolymer layer is polyimide. The material used for the corrosion-resistant polymer protective layer is polytetrafluoroethylene.

[0040] Connection between the inner tube layer and the composite gas barrier layer: Connection method: The connection between the inner tube layer and the composite gas barrier layer (blended and modified PVDC layer) is completed through a welding or bonding process. Since the composite gas barrier layer is usually formed by coextrusion of multiple layers (PVDC, EVOH, PA coextrusion), they can form a tight bonding interface on the surface of the inner tube layer to ensure seamless connection.

[0041] Connection between the composite gas barrier layer and the high-temperature resistant copolymer layer: Connection method: When connecting the composite gas barrier layer (blended and modified PA layer) and the high-temperature resistant copolymer layer (polyimide), surface pretreatment is first carried out to enhance the interfacial adhesion. Polyimide has excellent properties at high temperatures, so it plays a protective role in the high-temperature environment of the pipeline. Then it is combined with the gas barrier layer through bonding.

[0042] Connection between the reinforcement layer and the corrosion-resistant polymer protective layer: Connection method: The connection between the reinforcement layer and the corrosion-resistant protective layer is carried out by chemical bonding or hot melt bonding methods. It is combined with the reinforcement layer through a welding process or adhesive bonding technology to ensure that the pipeline does not leak in a harsh chemical environment.

[0043] During the preparation process of the composite gas barrier layer, the preparation parameters are as shown in Table 1 below:

[0044] ;

[0045] Performance detection, as shown in Table 2:

[0046] ;

[0047] Analysis of test results: Hydrogen permeability: Test method: According to ASTM D1434, the permeation rate of hydrogen in the pipeline material is tested to evaluate the airtightness of the pipeline. The PVDC, EVOH, and PA layers in the composite material are the main gas barrier materials, and their permeabilities need to be very low to effectively prevent hydrogen leakage. Analysis: The multi-layer structure of the composite gas barrier layer, especially the nano-modification and enhanced gas barrier ability of the PVDC layer, should be able to significantly reduce the hydrogen permeability.

[0048] High-temperature stability: Test method: Thermogravimetric analysis (TGA) is used to determine the thermal decomposition temperature of the composite material at high temperatures. Polyimide can maintain its stability at high temperatures, so high-temperature resistance is particularly crucial. Analysis: The high-temperature resistant copolymer layer (polyimide) has good thermal stability and effectively protects the pipeline from material degradation in a high-temperature environment.

[0049] Corrosion resistance: Test method: Simulate the corrosive environment through salt spray test to evaluate the corrosion resistance of polytetrafluoroethylene (PTFE). Analysis: The use of the corrosion-resistant protective layer (PTFE) should be able to effectively prevent the pipeline from being damaged in a corrosive environment, especially in harsh chemical or wet environments.

[0050] Wear resistance: Test method: Use Taber abrasion test to evaluate the wear resistance of the reinforcement layer. Analysis: Through the reinforcement layer of carbon fiber reinforced epoxy resin, the pipeline surface has high wear resistance, which can reduce the loss during long-term use and increase the service life of the pipeline.

[0051] Compressive strength and tensile strength: Test method: Use compression test and tensile test to check the performance of the inner pipe layer and the reinforcement layer under high pressure and tension. Analysis: The inner pipe layer uses reinforced thermoplastics, combined with the carbon fiber epoxy resin structure of the reinforcement layer, which can maintain good structural strength in high-pressure and high-tension environments.

[0052] Heat resistance: Test method: Evaluate the stability of the material under high-temperature conditions through heat distortion temperature test.

[0053] Analysis: The heat resistance of the inner pipe layer and the high-temperature resistant copolymer layer meets the requirements for long-term use in high-temperature environments.

[0054] Antioxidation: Test method: Evaluate the stability of the material in an oxidative environment through oxidation induction time (OIT) test. Analysis: Especially the materials of the composite gas barrier layer and the reinforcement layer have good antioxidant properties, which can extend the service life and avoid oxidative degradation.

[0055] Hydrogen leakage test: Test method: Detect the hydrogen leakage situation of the pipeline to ensure the sealing performance of the pipeline in a high-pressure hydrogen environment. Analysis: The multi-layer structure of the composite gas barrier layer, especially the blend modification of PVDC and EVOH, should effectively prevent hydrogen leakage.

[0056] Dimensional stability: Test method: Test the dimensional changes of the material in high-temperature or high-humidity environments. Analysis: The composite material should maintain dimensional stability to avoid pipeline deformation caused by thermal expansion and contraction or environmental changes.

[0057] Summary: Through the multi-layer structure and fine material selection, this composite material pipeline is designed with multiple properties such as efficient hydrogen leakage protection, high temperature resistance, corrosion resistance, and wear resistance, ensuring the long-term stability of the pipeline in various complex environments. The efficient synergistic effect of the materials at each layer (such as the composite gas barrier layer, the reinforcement layer, and the protective layer) shows excellent indicators in performance testing and is suitable for applications where hydrogen leakage prevention is required.

[0058] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar means for substitution, but will not deviate from the spirit of the present invention or exceed the defined scope. Specifically, the present invention encompasses additional embodiments having any combination of features from the different embodiments described above. With respect to the use of the expressions "generally" or "substantially", this patent application should be understood to disclose that the same fully meet these features and values, i.e., without the foregoing being characterized as "generally" or "substantially".

Claims

1. A composite material pipeline for preventing hydrogen leakage, characterized in that, The composite material pipeline includes an inner pipe layer, a composite gas barrier layer located on the outer surface of the inner pipe layer, a high-temperature resistant copolymer layer located on the outer surface of the composite gas barrier layer, a reinforcing layer located on the outer surface of the high-temperature resistant copolymer layer, and a corrosion-resistant polymer protective layer located on the outer surface of the reinforcing layer; the composite gas barrier layer is a multi-layer co-extrusion molding structure. In the order from the inside to the outside, the composite gas barrier layer includes a blended and modified PVDC layer, a blended and modified EVOH layer, and a blended and modified PA layer. In the blended and modified PVDC layer, nano-clay, a PVDC layer toughening agent, a PVDC layer cross-linking agent, and an antioxidant are added. The materials used are in a weight ratio of PVDC resin:nano-clay:PVDC layer toughening agent:PVDC layer cross-linking agent:antioxidant of 75 - 77:3 - 5:6 - 8:1 - 2:0.3 - 0.5; the PVDC layer toughening agent is polyethylene or polypropylene, and the PVDC layer cross-linking agent is specifically TBPB. In the blended and modified EVOH layer, talcum powder, an EVOH layer cross-linking agent, and an antioxidant are added. The materials used are in a weight ratio of EVOH resin:talcum powder:EVOH layer cross-linking agent:antioxidant of 78 - 82:7 - 9:1.5 - 2:0.4 - 0.6; during the preparation of the EVOH layer, glycerol is added, and in a weight ratio, EVOH resin:glycerol is 100:3 - 5; the EVOH layer cross-linking agent is DCP. In the blended and modified PA layer, polyvinyl alcohol, nano-montmorillonite, a PA layer plasticizer, and an antioxidant are added. The materials used are in a weight ratio of PA resin:polyvinyl alcohol:nano-montmorillonite:PA layer plasticizer:antioxidant of 100:2.5 - 3:3 - 5:1.5 - 2.5:0.4 - 0.6; the PA layer plasticizer is TPP. The reinforcing layer is prepared by a vacuum-assisted resin transfer molding method. The materials used are in a weight ratio of carbon fiber:epoxy resin:amorphous nano-silica of 60 - 70:30 - 40:5 - 8.

2. The composite material pipeline for preventing hydrogen leakage according to claim 1, wherein, The material of the inner pipe layer is one of RTP and TCP.

3. The composite material pipeline for preventing hydrogen leakage according to claim 1, wherein, The material used for the high-temperature resistant copolymer layer is polyimide.

4. The composite material pipeline for preventing hydrogen leakage according to claim 1, characterized in that, The material used for the corrosion-resistant polymer protective layer is polytetrafluoroethylene or a fluorinated ethylene-propylene copolymer.

5. The composite material pipeline for preventing hydrogen leakage according to claim 1, wherein, The reinforcing layer adopts a multi-layer interwoven fiber structure. The laying direction of each layer of fiber is 0° / 90° or ±45°, the number of layers is 3 - 7 layers, and at least one layer adopts ±45°; during the curing process of the reinforcing layer, a temperature-controlled curing box is used, and the temperature inside the curing box is set to 130°C to 150°C; a modified polyamine curing agent is selected as the curing agent for the epoxy resin, and the curing time is 2 - 4 hours.