A port insulation composite structure, a preparation method thereof and an insulation assembly

Abstract

The application discloses a port insulation composite structure, a preparation method thereof and an insulation assembly. The insulation composite structure comprises a first outer layer, a compression-resistant core layer and a second outer layer in sequence. The compression-resistant core layer comprises a flat fiber fabric, an epoxy resin matrix and carbon fiber particles. At least part of the carbon fiber particles are inserted into the fiber fabric. The first outer layer, the compression-resistant core layer and the second outer layer are formed into an integrated structure. The volume resistivity of the insulation composite structure is 6*10 6 ~ 6*10 8 Ω*cm at 20~30 DEG C. The volume resistivity of the insulation composite structure is 1*10 6 ~ 2*10 8 Ω*cm at a high temperature above 80 DEG C. The application utilizes the insulation composite structure and the insulation gasket to construct a pipeline insulation assembly with moderate insulation, compression resistance, wear resistance, high-temperature resistance, acid and alkali resistance and other excellent comprehensive performances on the basis of a flange set, connecting bolts and connecting nuts of an existing port connecting pipeline. The pipeline insulation assembly is simple to install and widely applicable.

Description

Technical Field

[0001] This invention belongs to the field of insulation structure technology, and specifically relates to an insulating composite structure for ports, its preparation method, and insulating components. Background Technology

[0002] In ship-to-port oil and gas transportation systems, the flange connection between the ship and shore is a critical structure for ensuring transportation safety. Especially in special operational scenarios such as dock equipment maintenance and pipeline welding, the insulation structure must remain in place to continuously achieve reliable insulation isolation. This places extremely high demands on the stability, durability, and safety of the insulation structure. Currently, ship-to-shore flange insulation connections widely employ combinations of components such as insulating gasket assemblies and bolt insulating sleeves to achieve electrical isolation. Among these, the insulating gasket is the core component, primarily composed of layered composite materials. However, under the harsh conditions of long-term heavy loads, frequent disassembly and assembly, salt spray corrosion, and oil contamination at oil terminals, existing insulating gasket materials exhibit varying degrees of technical defects, making it difficult to consistently meet regulatory requirements and insulation needs in special scenarios over the long term.

[0003] Invention patent CN113195957B discloses a self-adhesive flexible mineral wool laminate material for isolating metal sheet pipes or cavities. It includes a mineral wool insulating pad, a first fabric laminated to its first main surface, and a double-sided adhesive structure with pressure-sensitive adhesive. It is mainly used for thermal and acoustic insulation of metal pipes or cavities in HVAC systems. While this material uses mineral wool as the core insulating layer, its flexible and porous structure results in extremely low compressive strength. Under the preload of flange bolts, it will undergo severe deformation or even crushing, making it impossible to maintain a stable geometry and thickness between pipe flange sealing surfaces. Furthermore, the electrical insulation performance of its self-adhesive interface layer and its chemical stability in oil and salt spray media cannot meet the stringent requirements of ship-to-shore insulating flanges, making the overall structure unsuitable for ship-to-shore flange insulation connections.

[0004] Chinese patent application CN121316357A discloses a highly insulating tearable laminated gasket, which consists of multiple layers of highly insulating films stacked sequentially and bonded together with an adhesive to form a laminated structure. While the core design objectives of this patent application are adjustable thickness and high insulation, the layers are bonded together using adhesives. Under high flange pressure and dynamic loads from frequent disassembly and assembly, the interlayer bonding interfaces are prone to shear cracking and delamination failure, compromising the overall structural integrity. Furthermore, the mechanical strength, compressive strength, and abrasion resistance of the tearable laminated structure are insufficient, making it difficult to maintain a stable and reliable insulation barrier effect under the special working conditions of long-term installation of ship-shore insulating flanges.

[0005] Furthermore, electrical insulation measures should be implemented between oil and gas chemical terminals and operating vessels. The resistance value of the non-conductive short pipe attached to the insulated flange or hose of the loading arm should not be less than 25kΩ and should not exceed 2.5MΩ. A resistance value less than 25kΩ cannot interrupt stray currents between the ship and shore, easily forming a large loop current, which could ignite and explode the oil and gas mixture. A resistance value greater than 2.5MΩ indicates excessive insulation performance, making it impossible for the flange to discharge static electricity between the ship and shore, creating a high potential difference. In the event of accidental contact or breakdown, an electric spark may be generated, igniting the oil and gas mixture and causing a fire or explosion. Currently, external parallel bypass resistors are often used specifically for discharging static electricity. In addition to the need to add and frequently check the bypass resistors, they are also prone to disconnection during dynamic production processes, affecting the conduction of static electricity and causing the risk of excessively high resistance values.

[0006] Therefore, how to provide a port insulation composite structure with suitable insulation properties, excellent compressive strength and wear resistance, as well as weather resistance and high temperature resistance, and use it for insulation connection between port pipelines is an urgent problem to be solved in this field. Summary of the Invention

[0007] To address the shortcomings of the existing technologies, this invention provides a port-use insulating composite structure, its preparation method, and insulating components. By utilizing the port-use insulating composite structure and the insulating gaskets made therefrom, an insulating component for port pipeline connections with excellent comprehensive performance, such as suitable insulation, pressure resistance, wear resistance, temperature resistance, and weather resistance, can be efficiently and universally constructed based on existing flange assemblies, connecting bolts, and connecting nuts. Moreover, it is simple to install, requires no additional bypass resistors to dissipate static electricity, and is low in cost and widely applicable.

[0008] The first aspect of this invention provides an insulating composite structure for ports, comprising, in sequence: i) The first outer layer, with a thickness of 0.5 to 1.5 mm, includes an epoxy resin matrix and a first filler dispersed therein; ii) The compressive core layer is a fiber-reinforced epoxy composite layer with a thickness of 1.0 to 4.0 mm, including an epoxy resin matrix and a second conductive filler and several fiber fabrics dispersed therein; The fiber fabric is laid flat along the compressive core layer, and the pore size of the fiber fabric is 10-30 μm; At least a portion of the second conductive filler is inserted into the fiber fabric. The second conductive filler comprises carbon fiber particles with a diameter of 5 to 10 μm and a length of 0.1 to 0.5 mm. iii) The second outer layer, with a thickness of 0.5 to 1.5 mm, includes an epoxy resin matrix and a third filler dispersed therein; The first outer layer, the pressure-resistant core layer, and the second outer layer are molded into a single structure; The volume resistivity of the insulating composite structure used in ports is 6×10⁻⁶ at 20–30℃.6 ~6×10 8 Ω·cm; volume resistivity at temperatures above 80℃ is 1×10 Ω·cm 6 ~2×10 8 Ω·cm.

[0009] Furthermore, the room temperature compressive strength of the insulating composite structure is not less than 260 MPa, and the flexural strength is not less than 400 MPa.

[0010] This invention employs a three-layer integrated composite structure design—outer layer-core layer-outer layer—to layer and enhance structural functionality. The pressure-resistant core layer, through a flat-laid fiber fabric skeleton and a second conductive filler, synergistically reinforces the epoxy resin matrix. The use of a flat, continuous fiber fabric imparts extremely high compressive strength and flexural stiffness to the overall structure, effectively withstanding the continuous high pressure from flange bolt tightening and providing appropriate insulation for port ship-shore connections. Secondly, the first and second outer layers provide wear resistance and appropriate insulation protection at their contact surfaces. Furthermore, the three-layer epoxy matrix co-curing and integral molding eliminates the risk of interlayer interface weakening, preventing delamination or cracking under high pressure and frequent disassembly / reassembly conditions. This ensures stable and uniform excellent mechanical and electrical properties under both normal and high-temperature conditions, meeting the long-term safety requirements of insulated flange connections between port pipelines.

[0011] Furthermore, the compressive core layer also satisfies at least one of the following: (1) The mass of the fiber fabric accounts for 45-65% of the total mass of the compressive core layer; (2) Fiber fabrics include at least one of glass fiber fabrics, quartz fiber fabrics, and aramid fiber fabrics; (3) The mass of the carbon fiber particles accounts for 5 to 10% of the total mass of the compressive core layer.

[0012] Furthermore, the fiber fabric includes alkali-free glass fiber fabric.

[0013] This invention controls the amount of fiber fabric used, ensuring the integrity of the fiber skeleton while providing sufficient impregnation space for the resin matrix. The pore size design allows carbon fiber particles, or chopped carbon fibers, to effectively embed into the fabric pores, forming a triple interlocking reinforcement network of fiber particles, fabric, and matrix. This significantly improves the interlaminar shear strength and impact toughness of the core layer, further enhancing overall compression and bending performance and preventing core layer indentation or cracking failure under heavy flange loads. In addition, the conductivity of the carbon fiber particles balances the high insulation of the matrix and fiberglass fabric, forming a weakly conductive channel within the pressure-resistant core layer, thereby meeting the insulation requirements for port ship-shore connections.

[0014] The epoxy resin used in this invention can be a commercially available epoxy resin, including but not limited to bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic type epoxy resin, alicyclic epoxy resin, etc.

[0015] Furthermore, the first filler and the third filler respectively include at least one of conductive carbon particles, silicon carbide micro powder, silicon carbide whiskers, and conductive titanate particles; The first outer layer and the second outer layer also include antioxidants and light stabilizers, respectively. TiO2 nanoparticles are added to the light stabilizers in the first and second outer layers for pre-compounding. The amount of TiO2 nanoparticles is 1-10% of the mass of the light stabilizer.

[0016] Furthermore, the pressure-resistant core layer includes at least one of antioxidants and light stabilizers.

[0017] Antioxidants are primarily used to improve the thermal stability of the composite structure, preventing physical aging in outdoor humid and high-temperature environments, and reducing color changes. Light stabilizers enhance the aging resistance of the composite structure under outdoor sunlight. This invention, through structural design and material composition adjustment, achieves an insulating composite structure with moderate volume resistivity, thus meeting port pipeline connection resistance standards. The addition of functional fillers such as antioxidants and light stabilizers, while maintaining both insulation and mechanical properties, significantly improves the durability of the insulating composite structure in outdoor high-temperature and high-humidity environments, extending maintenance and replacement cycles while maintaining ease of use.

[0018] Furthermore, the amount of antioxidant added is 0.1-5% of the total mass of the corresponding layer, preferably 0.5-2.5%, including but not limited to at least one of antioxidant 1010, antioxidant 1076, antioxidant 3114, antioxidant 168, and antioxidant 2103. Antioxidants 1010, 1076, and 3114 are high-performance hindered phenolic antioxidants, while antioxidants 168 and 2103 are phosphite antioxidants. The combination of these two types can simultaneously eliminate two types of harmful intermediate products (free radicals and hydroperoxides), which is beneficial for synergistically improving the overall antioxidant performance. Preferably, the antioxidants include antioxidant 1010 and antioxidant 168 in a mass ratio of 1:(0.1-4).

[0019] Furthermore, the amount of light stabilizer added is 0.1-3% of the total mass of the corresponding layer, and the light stabilizer includes, but is not limited to, at least one of UV326, UV327, UV329, UV1150, UV1577, UV531, and UV622.

[0020] Furthermore, the amount of the first and third fillers accounts for 0.1 to 10% of the total mass of the corresponding outer layer, preferably 1 to 8%.

[0021] Furthermore, the particle size of the first and third fillers is between 0.01 and 25 μm.

[0022] Furthermore, conductive carbon particles include at least one of carbon fiber particles (such as PAN-based carbon fiber particles), carbon black, and graphite. Depending on the layer thickness and insulation performance requirements, two types can also be used in combination, for example, carbon black and graphite can be combined in a ratio of (1-4):(1-3).

[0023] The first and third fillers use conductive fillers, such as conductive carbon-based particles, silicon carbide micro powder, silicon carbide whiskers, and conductive titanate particles. This not only improves the surface's wear resistance, allowing the insulating gasket to maintain a stable surface morphology under frequent disassembly and assembly, effectively extending its service life, but also helps to control electrical insulation performance. Controlling the filler dosage ensures that while fully leveraging the enhanced wear resistance, the outer layer does not become brittle due to excessive filler or lose its insulating properties due to excessively low resistance, thus maintaining the overall structure's toughness, reliability, and adequate insulation.

[0024] Furthermore, the fiber fabric, the first filler, the second conductive filler, and the third filler undergo surface treatment, and are independently selected from at least one of coupling agent treatment, plasma treatment, and electron beam treatment.

[0025] Surface treatment introduces active functional groups or improves surface wettability on the filler / fiber surface, significantly enhancing the interfacial bonding strength between the functional components and the epoxy resin matrix. Coupling agent treatment establishes chemical bond bridges between inorganic fillers and organic resins, eliminating interfacial micropores; plasma and electron beam treatments activate the fiber surface, increasing the contact angle and promoting resin wetting, enabling each layer to form a continuous, defect-free interfacial bond after curing. This effectively improves the overall mechanical properties, electrical insulation reliability, and aging and weather resistance stability of the insulating composite structure.

[0026] A second aspect of the present invention provides a method for preparing the aforementioned insulating composite structure for ports, comprising the following steps: S1. Prepare the adhesive solutions for each layer: Disperse the second conductive filler evenly in epoxy resin to obtain the core layer adhesive solution; disperse the first filler evenly in epoxy resin to prepare the first outer layer adhesive solution; disperse the third filler evenly in epoxy resin to prepare the second outer layer adhesive solution. S2. The fiber fabric is impregnated with core layer adhesive at least twice, and the impregnated fiber fabric is extruded and pre-cured by preheated rollers to obtain a pre-cured core layer. S3. Place the pre-cured core layer in the mold and use vacuum infusion process (VIP) or resin transfer molding process (RTM) to introduce the first outer layer adhesive and the second outer layer adhesive into the mold, respectively or simultaneously, to form an outer layer covering the upper and lower surfaces of the pre-cured core layer. S4. Perform stepped heating and co-curing to form the pre-cured core layer and outer layer into an integrated port insulation composite structure.

[0027] Furthermore, in step S2, the pre-cured fiber fabric is extruded and pre-cured using preheated rollers to obtain a pre-cured core layer, including the following steps: S2.1 At least two sets of preheated rollers are arranged sequentially to form a roller group to extrude a single-layer impregnated fiber fabric, wherein: The first pair of rollers is preheated to 60–80℃ with a spacing of 0.40–0.80 mm. The second pair of rollers has a preheating temperature of 90–110℃ and a spacing of 0.20–0.50 mm. S2.2 Pressing a predetermined number of layers of impregnated fiber fabric is performed using pressing rollers to obtain a pre-fixed core layer. The preheating temperature of the pressing rollers is 100-120℃, and the spacing is 1.00-4.0mm.

[0028] This invention employs "multi-stage impregnation" and "roller pre-curing" to ensure that the fiber fabric is fully wetted. The preheated roller assembly gradually removes air bubbles under gradient temperature and pressure, and controls the partial cross-linking of the resin to form a highly dense, pre-shaped pre-cured core layer. Then, "VIP / RTM outer layer coating" is used to uniformly introduce the outer layer adhesive and fully contact it with the interface of the pre-cured core layer, tightly wrapping the pre-cured core layer to form a high-quality intermediate without interlayer bubbles. Finally, the three epoxy resins of "outer layer-core layer-outer layer" are co-cured by stepwise temperature and pressure, promoting chemical bonding between the outer layer and the core layer interface, forming an integrated structure without interlayer weaknesses. This results in high molding consistency and is suitable for mass production.

[0029] The present invention employs a stepped parameter design with "temperature increment" for at least three sets of rollers. During the fiber fabric propulsion process, the rollers fully fill and impregnate the fabric, gradually increasing the degree of curing and compressing to achieve densification. The first rollers complete the initial impregnation and degassing under low temperature and wide spacing conditions. The second rollers further squeeze and drive away residual air bubbles under medium temperature and medium spacing conditions, causing the resin to begin gelation. Depending on the viscosity of the adhesive and the porosity of the fiber fabric, additional roller sets may be added to ensure sufficient filling of the fabric pores. Subsequently, the pressing rollers precisely fix the thickness of the impregnated fiber fabric with a preset number of layers under high temperature and short-time roller pressure and complete the controlled pre-curing. After the above pre-fixing process, the shrinkage of the core layer thickness after hot pressing is basically below 2%. Therefore, the spacing of the pressing rollers can be adjusted with reference to the required core layer thickness. This process effectively avoids defects such as difficulty in removing air bubbles, resin embrittlement, and fiber breakage caused by high-temperature rapid curing, and controls the thickness deviation of the pre-cured core layer within ±0.02mm. This provides a precise dimensional reference for subsequent outer layer coating and co-curing, thereby ensuring the thickness consistency and mechanical property uniformity of the final product.

[0030] Furthermore, the preparation method includes at least one of the following processes: (1) Before being dispersed in epoxy resin, the first filler, the second conductive filler and the third filler are treated with silane coupling agent; (2) The single or double side of the fiber fabric is treated online by atmospheric plasma, and then enters the first impregnation at the first conveying speed V1 and the second impregnation at the second conveying speed V2, wherein 1m / min≤V2≤V1≤10m / min; (3) Between at least two impregnations, at least one set of rollers is used to roll-press the fiber fabric for assisted impregnation; the assisted operation helps to fully press the impregnation resin into the micropores of the fabric and reduce the porosity. (4) After cutting the pre-solidified core layer and performing atmospheric plasma double-sided treatment, it is stacked in the mold.

[0031] Coupling agent treatment, plasma treatment, and electron beam treatment are effective means to improve the surface activity of fiber fabrics, first fillers, second conductive fillers, and third fillers. Using simple and appropriate methods depending on the specific material being treated is highly beneficial for improving the interfacial compatibility of dissimilar materials and enhancing the mechanical and insulating properties of the integrated structure. For example, using silane coupling agents (such as KH-550) to introduce organic functional groups onto the filler surface allows for the establishment of covalent bonds between the filler and the epoxy matrix, eliminating mechanical weaknesses caused by interfacial debonding and improving the mechanical strength of the insulating composite structure. Furthermore, using atmospheric plasma to activate continuously conveyed fiber fabrics and sheet-like pre-bonded core layers is beneficial for efficiently and quickly improving the bonding performance between the fiber fabric surface and the core layer adhesive, as well as between the pre-bonded core layer and the outer layer adhesive.

[0032] In the two-stage impregnation process, the first conveying speed of the first impregnation can be slightly higher than the second conveying speed of the second impregnation. The slower speed ensures that the resin has sufficient time for secondary penetration and to fill any micropores that may be left over from the first impregnation, achieving a combination of rapid pre-impregnation and thorough filling. Preferably, with inter-stage roller pressing to assist impregnation, the resin can be fully pressed into the interior of the fiber fabric, preventing excessive resin accumulation on the fabric surface to form a shell. In this case, the first conveying speed can also be the same as the second conveying speed, thereby improving the overall process continuity and production efficiency. In the above-mentioned impregnation stage of continuous fiber fabrics, the two-stage impregnation can further control the fabric porosity to within 2%, preferably not exceeding 1%, meeting the requirements of glass fiber reinforced materials for industrial-grade components.

[0033] Furthermore, in step S4, the stepped temperature co-curing includes the following steps: S4.1, First-stage heating to T1, simultaneously pressurizing to (40%~60%)×P, where T1 is 80~100℃, P is the final process pressure set at 0.1~0.5MPa, and holding at temperature and pressure for 15~30min; S4.2, Second-stage heating to T2, T2 is T1+ (20℃~50℃), simultaneous pressure increase to P, hold temperature and pressure for 15~30min; S4.3, raise the temperature to T3 in three stages, T3 is T2+ (10℃~40℃), keep the pressure P constant, and keep the temperature and pressure for 10~30min to obtain an integrated port insulation composite structure.

[0034] Furthermore, the heating rate should be controlled at 2-3℃ / min to avoid excessively rapid heating that could lead to resin embrittlement or interlayer delamination.

[0035] Furthermore, after curing, cool to room temperature at a rate of 1-2℃ / min before demolding.

[0036] The three-stage co-curing process divides the curing process into three stages: low-temperature initial setting, medium-temperature gelation, and high-temperature complete cross-linking. This is coordinated with a simultaneous pressurization strategy. The process includes: a first-stage low-temperature, low-pressure stage allows the resin to flow fully at low viscosity and expel entrained gases, ensuring the outer layer adhesive penetrates and wets the interface region; a second-stage medium-temperature to full-pressure stage ensures gelation is completed under high pressure, resulting in a tight bond between the outer layer and the pre-cured core layer; and a third-stage high-temperature holding-pressure stage drives the resin to fully cross-link and cure, eliminating residual stress and ultimately locking in the mechanical state of the integrated structure. This co-curing process effectively prevents resin embrittlement or interlayer delamination caused by excessively rapid heating, ensuring the interlayer bonding strength and dimensional stability of the final product.

[0037] A third aspect of the present invention provides an insulating assembly for port pipeline connections, comprising a flange assembly, connecting bolts, connecting nuts, nut insulating washers, and heat-shrinkable insulating sleeves; One end of the connecting bolt passes through the flange assembly and is locked in place by the connecting nut; The heat-shrinkable insulating sleeve shall at least cover the surface of the bolts located within the flange assembly. Two sets of nut insulating washers are respectively fitted onto both ends of the connecting bolts and held against the outer side of the flange assembly. The nut insulating washers include the aforementioned port insulating composite structure. The insulation component provides an insulation resistance value of 1 to 2.5 MΩ between the connecting pipes.

[0038] This invention utilizes a nut insulating washer and a heat-shrinkable insulating sleeve to form a comprehensive, synergistic isolation layout of "end-face insulation + screw wrapping," effectively blocking conductive paths from both the bolt surface and the outer side of the flange. The nut insulating washer, relying on the high compressive strength of the port-grade insulating composite structure, remains undeformed and uncrushed under bolt tightening preload, thus stably blocking the current path on the nut-flange contact surface over the long term. The heat-shrinkable insulating sleeve wraps around the screw, achieving complete isolation between the screw and the flange bore wall. The combined effect of these two components stabilizes the overall insulation resistance at 1–2.5 MΩ, meeting the long-term insulation safety requirements of ship-shore operations.

[0039] The heat shrinkable insulating sleeve can be a commercially available single-layer or multi-layer heat shrinkable insulating sleeve, preferably a heat shrinkable insulating sleeve that includes at least two heat shrinkable tubing layers. The heat shrinkable insulating sleeve includes, but is not limited to, one or more layers of polyolefin heat shrinkable tubing, polyvinyl chloride heat shrinkable tubing, polytetrafluoroethylene heat shrinkable tubing, polyvinylidene fluoride heat shrinkable tubing, fluorinated ethylene propylene copolymer heat shrinkable tubing, polyester heat shrinkable tubing, and ethylene / vinyl acetate heat shrinkable tubing.

[0040] Furthermore, the flange assembly includes two flanges located at different pipe ends, and a flange insulating gasket assembly sandwiched between the two flanges. The flange insulating gasket assembly includes a flange gasket and flange insulating gaskets disposed on both sides of the flange gasket and abutting against the inner surface of the corresponding flange. The flange insulating gaskets include the port insulation composite structure.

[0041] In addition to the structural design of the nut insulating washer, this invention also employs a sandwich structure of "flange insulating washer-flange washer-flange insulating washer" for the flange insulating gasket assembly. This achieves both sealing performance and electrical insulation simultaneously between the flange sealing surface and the fluid passage. Because the flange insulating gasket is made of a port-grade insulating composite structure, it possesses sufficient compressive strength and flexural stiffness to withstand the flange bolt preload. Simultaneously, its excellent volume resistivity establishes a reliable insulation barrier between the flanges. Therefore, the selection of flange gasket materials expands to include a wide range of insulating and non-insulating materials. Even when using conductive materials, such as metal gaskets, the insulation effect between flanges can be met, thus effectively improving the overall performance of the flange connection, including sealing, weather resistance, and corrosion resistance. Overall, the flange insulating gasket assembly, together with the nut insulating washer and heat-shrinkable insulating sleeve, constitutes a three-dimensional, end-to-end insulation system from the flange gap to the bolt system, further enhancing the overall insulation reliability of the insulation components and meeting the highest safety level requirements for long-term insulation at oil terminals.

[0042] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: (1) The present invention adopts a three-layer integrated composite structure design of “outer layer-core layer-outer layer”. The pressure-resistant core layer adopts a composite system of epoxy resin reinforced by a flat fiber fabric and a second conductive filler to achieve excellent compressive strength, flexural strength and appropriate insulation performance. The first outer layer and the second outer layer respectively provide enhanced wear-resistant protection, adjustable insulation performance and light resistance and anti-aging performance, making the insulating composite structure obtained by the present invention particularly suitable for various insulation parts of port connections.

[0043] (2) The present invention adopts a combination of preheating roller group step impregnation pre-curing and vacuum introduction / RTM outer layer coating step heating co-curing process, which realizes the enhanced interface chemical bonding between each layer, ensures that the outer layer-core layer integrated structure has no delamination and high molding consistency.

[0044] (3) The present invention utilizes the nut insulating washer made of the port insulating composite structure, and the encapsulated bolt insulating layout of the heat shrink insulating sleeve to achieve full-path electrical isolation of the bolt-nut system, and obtains a pipeline insulation resistance of 1 to 2.5 MΩ, which is well adapted to the port pipeline connection operation requirements, and there is no need to arrange a bypass resistor to dissipate static electricity.

[0045] (4) In the insulating assembly for port pipeline connection of the present invention, the flange insulating gasket group adopts a sandwich structure of "flange insulating gasket-flange gasket-flange insulating gasket", which realizes the dual functions of sealing performance and electrical insulation between the flange sealing surface and the fluid passage. At the same time, it relies on the excellent volume resistivity to establish a reliable insulating isolation barrier between the flanges, expands the selection range of flange gaskets, and effectively improves the comprehensive performance of flange connection such as sealing performance, high temperature resistance and acid and alkali resistance, and meets the highest safety level requirements for long-term insulation of oil terminals. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the insulating composite structure for ports according to the present invention; Figure 2 This is a schematic diagram of an insulating gasket made from the insulating composite structure for ports according to the present invention; Figure 3 This is a schematic diagram of the structure of the insulating assembly for port pipeline connection according to the present invention; Figure 4 This is a schematic diagram of the structure of another insulating component for port pipeline connection according to the present invention; Figure 5 This is a schematic diagram of the actual connection of the insulating assembly for port pipeline connection according to the present invention; Figure 6 The surface condition of the nut insulating washer after five tightening and loosening cycles; Figure 7 This is the side view of the nut insulating washer after 5 tightening and loosening cycles.

[0047] Explanation of reference numerals in the attached drawings: 11-First outer layer, 12-Compression-resistant core layer, 13-Second outer layer; 100-Insulating component, 1-Nut insulating washer, 2-Heat shrink insulating sleeve, 3-Flange assembly, 31-Flange gasket, 32-Flange insulating gasket, 4-Connecting bolt, 5-Connecting nut. Detailed Implementation

[0048] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0049] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0050] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0051] This invention provides an insulating composite structure for ports, see below. Figure 1 and Figure 2 In order, they include: i) The first outer layer 11 has a thickness of 0.5 to 1.5 mm and includes an epoxy resin matrix and a first filler dispersed therein, as well as an antioxidant and / or a light stabilizer; the first filler includes a conductive filler and is preferably subjected to at least one surface treatment selected from coupling agent treatment, plasma treatment, and electron beam treatment. ii) The compression-resistant core layer 12 is a fiber-reinforced epoxy composite layer with a thickness of 1.0 to 4.0 mm, including: a number of fiber fabrics laid flat along the compression-resistant core layer 12, an epoxy resin matrix and a second conductive filler dispersed therein, as well as antioxidants and / or light stabilizers; The fiber fabric is preferably a continuous fiber fabric; the fiber fabric accounts for 45-65% of the total mass of the compression-resistant core layer 12, including at least one of glass fiber fabric (more preferably alkali-free glass fiber fabric), quartz fiber fabric, and aramid fiber fabric, and the pore size of the fiber fabric is 10-30 μm; the second conductive filler includes carbon fiber particles, the carbon fiber particles account for 5-10% of the total mass of the compression-resistant core layer 12, the diameter is 5-10 μm, the length is 0.1-0.5 mm, and at least some of the carbon fiber particles are inserted into the fiber fabric; the fiber fabric and the second conductive filler are preferably subjected to at least one of the following surface treatments: coupling agent treatment, plasma treatment, and electron beam treatment, and more preferably, the single or double sides of the continuous fiber fabric are treated with plasma online; iii) The second outer layer 13 has a thickness of 0.5 to 1.5 mm and includes an epoxy resin matrix and a third filler dispersed therein, as well as an antioxidant and / or a light stabilizer; the third filler includes a conductive filler, preferably having undergone at least one surface treatment of coupling agent treatment, plasma treatment, or electron beam treatment. The first outer layer 11, the pressure-resistant core layer 12, and the second outer layer 13 are formed into an integral structure. The compressive strength of the insulating composite structure is not less than 260MPa, and the bending strength is not less than 400MPa. The first and third fillers include conductive fillers with a particle size of 0.01 to 25 μm, and the amount used accounts for 0.1 to 10% of the total mass of the corresponding outer layer, preferably 1 to 8%, including at least one of conductive carbon particles, silicon carbide micro powder, silicon carbide whiskers, and conductive titanate particles. In a preferred embodiment, to reduce resistivity, a combination of large and small fillers can be used with conductive fillers to form more micro-conductive pathways.

[0052] In a preferred embodiment, functional fillers such as antioxidants and / or light stabilizers are added to the first outer layer 11, the second outer layer 13, and the optional pressure-resistant core layer 12. Antioxidants are primarily used to improve the thermal stability of the composite structure, prevent the physical properties of the composite structure from aging under outdoor humid and high-temperature environments, and help reduce color changes. Light stabilizers help improve the aging resistance of the composite structure in outdoor light environments.

[0053] The amount of antioxidant added is 0.1-5% of the total mass of the corresponding layer, preferably 0.5-2.5%, including but not limited to at least one of antioxidant 1010, antioxidant 1076, antioxidant 3114, antioxidant 168, and antioxidant 2103. It is preferred to use two in combination, for example, antioxidant 1010 and antioxidant 168 in a mass ratio of 1:(0.1-4).

[0054] The amount of light stabilizer added is 0.1-3% of the total mass of the corresponding layer. The light stabilizer includes, but is not limited to, at least one of UV326, UV327, UV329, UV1150, UV1577, UV531, and UV622. More preferably, TiO2 nanoparticles are added to the light stabilizer of the first outer layer 11 and the second outer layer 13 for premixing and compounding. The amount of TiO2 nanoparticles is 1-10% of the mass of the light stabilizer, thereby better enhancing the aging resistance of the outer layer.

[0055] The epoxy resin matrix includes, but is not limited to, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic type epoxy resin, alicyclic epoxy resin, etc. The epoxy resins in the first outer layer 11, the pressure-resistant core layer 12 and the second outer layer 13 can be of the same type or different types.

[0056] The volume resistivity of the insulating composite structure used in ports is 6×10⁻⁶ at 20–30℃. 6 ~6×10 8 Ω·cm; volume resistivity at temperatures above 80℃ is 1×10 Ω·cm 6 ~2×10 8 Ω·cm.

[0057] This invention also provides a method for preparing the above-mentioned insulating composite structure for ports, comprising the following steps: S1. Prepare the adhesive solutions for each layer: Preferably, the first filler, the second conductive filler, and the third filler are pre-treated with a silane coupling agent for surface activation, including: Prepare a silane coupling agent treatment solution in advance (e.g., using KH-550). Select three portions of silane coupling agent, each containing 0.5%-5.0% by mass of the first, second, and third packing materials, and add them to ethanol and water in a volume ratio of (3-6):1. Adjust the pH to 4-5 to obtain three portions of silane coupling agent treatment solution corresponding to the first, second, and third packing materials. After hydrolyzing and activating the three portions of silane coupling agent treatment solution by stirring at 25-30℃ for 30-60 minutes, add the corresponding packing materials and mix evenly. Treat at 50-70℃ for 1-3 hours, filter or centrifuge, and wash 2-3 times with ethanol or acetone. Dry at 80-110℃ for 2-4 hours under vacuum or inert gas environment to obtain the three types of packing materials treated with silane coupling agent. The second conductive filler treated with silane coupling agent, and optional antioxidants and / or light stabilizers are uniformly dispersed in epoxy resin to obtain the core layer adhesive. The first outer layer adhesive is prepared by uniformly dispersing the first filler treated with silane coupling agent, and optional antioxidants and / or light stabilizers in epoxy resin. The second outer layer adhesive is prepared by uniformly dispersing the third filler treated with silane coupling agent, and optional antioxidants and / or light stabilizers in epoxy resin. S2. The fiber fabric is subjected to single-sided or double-sided online treatment by atmospheric plasma, and then the fiber fabric is impregnated with core layer adhesive in at least two stages. Preferably, between the at least two impregnation stages, the fiber fabric is subjected to roller-assisted impregnation using at least one set of rollers. The impregnated fiber fabric is then extruded and pre-cured using preheated rollers to obtain a pre-cured core layer with a pre-curing degree of 30%-60%, specifically including: S2.1 At least two sets of preheated rollers are arranged sequentially to form a roller group to extrude a single-layer impregnated fiber fabric, wherein: The first pair of rollers is preheated to 60–80℃ with a spacing of 0.40–0.80 mm. The second pair of rollers has a preheating temperature of 90–110℃ and a spacing of 0.20–0.50 mm. S2.2 Pressing a predetermined number of layers of impregnated fiber fabric with pressing rollers to obtain a pre-fixed core layer, wherein the preheating temperature of the pressing rollers is 100-120℃ and the spacing is 1.00-4.0mm; S3. After the pre-cured core layer is cut and subjected to double-sided treatment by atmospheric plasma, it is stacked in the mold. The first outer layer adhesive and the second outer layer adhesive are introduced into the mold separately or simultaneously using a vacuum introduction process (VIP) with a negative pressure of -0.04~-0.05MPa or a resin transfer molding process (RTM) with a pressure of 0.15-0.25MPa. When the first outer layer adhesive and the second outer layer adhesive use the same formula, it is preferable to introduce the first outer layer adhesive and the second outer layer adhesive simultaneously to form an outer layer covering the upper and lower surfaces of the pre-cured core layer. S4, Stepped temperature co-curing: S4.1. Heat the mold to 80-100℃ in one step, and simultaneously pressurize it to 0.04-0.3MPa, and hold the temperature and pressure for 15-30 minutes. S4.2. The mold is heated to 100℃~150℃ in a second stage, and the pressure is increased to 0.1~0.5MPa simultaneously. The temperature and pressure are maintained for 15~30min. S4.3. The mold is heated in three stages to 110℃~190℃, and the pressure is kept constant at 0.1~0.5MPa. The temperature and pressure are maintained for 10~30min. The mold is then removed to obtain an integrated port insulation composite structure.

[0058] After obtaining the insulating composite structure for port applications, it can be further processed through cutting, punching, and other operations to produce various high-performance insulating products. For example, a ring-shaped insulating washer is provided for use in insulating components for port pipelines; see attached document. Figure 3 and Figure 5The pipe insulation assembly 100 includes a flange assembly 3, connecting bolts 4, connecting nuts 5, nut insulating washers 1, and heat shrink insulating sleeves 2. One end of the connecting bolt 4 passes through the flange assembly 3 and is locked in place by the connecting nut 5; The heat-shrinkable insulating sleeve 2 shall at least cover the surface of the bolts 4 located within the flange assembly 3; Two sets of nut insulating washers 1 are respectively fitted onto both ends of the connecting bolt 4 and abut against the outer side of the flange. The nut insulating washers 1 include the above-mentioned port insulating composite structure.

[0059] In a preferred embodiment, see Figure 4 The flange assembly 3 includes two flanges located at different pipe ends, and a flange insulating gasket assembly sandwiched between the two flanges. The flange insulating gasket assembly includes a flange gasket 31 and flange insulating gaskets 32 disposed on both sides of the flange gasket 31 and abutting against the inner side of the corresponding flange. The flange insulating gasket 32 ​​includes the port insulating composite structure. The insulation component 100 provides an insulation resistance value of 1 to 2.5 MΩ between the connecting pipes to achieve a suitable insulation connection between the port pipes.

[0060] Example 1 The total thickness of the port insulation composite structure in Example 1 is approximately 3.5 mm, and it sequentially includes a first outer layer of integral structure, a pressure-resistant core layer, and a second outer layer, wherein: i) The first outer layer, with a thickness of approximately 1.0 mm, is made of bisphenol A epoxy resin and conductive carbon black, artificial graphite powder, antioxidants, and light stabilizers dispersed therein. The conductive carbon black has a particle size of approximately 20-50 nm and is used at 3% of the total mass of the first outer layer. The artificial graphite powder has a particle size of approximately 10-15 μm and is used at 2% of the total mass of the first outer layer. The antioxidant is used at 1.0% of the total mass of the first outer layer, and antioxidant 168 and antioxidant 1010 are compounded in a 1:1 mass ratio. The light stabilizer UV327 is used at 1% of the total mass of the first outer layer, and 5% of TiO2 nanoparticles (approximately 0.05% of the total mass of the first outer layer) are added for premixing and compounding.

[0061] ii) The compressive core layer, with a thickness of approximately 1.5 mm, comprises: an alkali-free glass fiber fabric laid flat along the core layer, the pore size of the fiber fabric being 15±3 μm, and a single layer thickness of approximately 0.20±0.02 mm, the alkali-free fiber fabric accounting for 54% of the total mass of the compressive core layer; Bisphenol A epoxy resin and carbon fiber particles dispersed therein, as well as antioxidants and light stabilizers, wherein the carbon fiber particles have a diameter of approximately 8±2μm and a length of 0.1 to 0.2mm, and account for approximately 6% of the total mass of the compressive core layer; antioxidants, accounting for 0.5% of the total mass of the core layer, are compounded with antioxidant 168 and antioxidant 1010 in a mass ratio of 1:1; and light stabilizer UV327, accounting for 0.5% of the total mass of the first outer layer.

[0062] iii) The second outer layer has the same formula and thickness as the first outer layer.

[0063] The insulating composite structure for ports in Example 1 is prepared by the following method, specifically including the following steps: S1. Prepare the adhesive solutions for each layer: The conductive carbon black, artificial graphite powder and carbon fiber particles were surface activated using KH-550 silane coupling agent solution. Carbon fiber particles treated with silane coupling agent are uniformly dispersed in epoxy resin E-51 (containing anhydride curing agent) to obtain core layer adhesive. Conductive carbon black treated with silane coupling agent and artificial graphite powder are uniformly dispersed in epoxy resin E-51 (containing acid anhydride curing agent) to prepare the first outer layer adhesive and the second outer layer adhesive. S2. The alkali-free glass fiber fabric is subjected to double-sided online treatment by atmospheric plasma, and then the fiber fabric is impregnated twice with core layer adhesive. The fiber fabric is conveyed at a speed of 5m / min. Between the two impregnations, a set of rollers is used to assist the impregnation by roller pressing. The impregnated fiber fabric is then extruded and pre-cured using preheated rollers to obtain a pre-cured core layer with a pre-curing degree of approximately 40%, specifically including: S2.1 At least two sets of preheated rollers are arranged sequentially to form a roller group to extrude a single-layer impregnated fiber fabric, wherein: The first pair of rollers is preheated to 65℃ with a spacing of approximately 0.60mm. The second pair of rollers is preheated to 100℃ and has a spacing of approximately 0.35mm. S2.2 The five layers of impregnated fiber fabric are pressed together using pressing rollers to obtain a pre-fixed core layer. The preheating temperature of the pressing rollers is 110℃, the spacing is about 1.50mm, and a pre-fixed core layer with a thickness of about 1.50mm is obtained. S3. After the pre-cured core layer is cut and treated with atmospheric plasma on both sides, it is stacked in the mold. A vacuum introduction process (VIP) is adopted to maintain a negative pressure of about -0.05MPa. At the same time, the first outer layer adhesive and the second outer layer adhesive are introduced from the upper and lower feed ports of the mold to form the first outer layer and the second outer layer covering the surface of the pre-cured core layer. S4, Stepped temperature co-curing: S4.1. Heat the mold to 95℃ in one step, and simultaneously pressurize it to 0.15MPa, and hold the temperature and pressure for 20 minutes. S4.2. The mold is heated to 125℃ in a second stage, and the pressure is increased to 0.3MPa simultaneously. The temperature and pressure are maintained for 20 minutes. S4.3. The mold is heated to 150℃ in three stages, and the pressure is kept constant at 0.3MPa for 20 minutes. S4.4 Demolding process is performed on the mold to obtain an integrated insulating composite structure for ports.

[0064] Example 2 The difference between Example 2 and Example 1 in the port insulation composite structure lies in the thickness of each layer and the total thickness. In Example 2: i) The first outer layer, approximately 1.0 mm thick; ii) Compression-resistant core layer, approximately 2.5 mm thick; iii) The second outer layer has the same formula and thickness as the first outer layer.

[0065] The total thickness of the insulating composite structure for ports in Example 2 is approximately 4.5 mm.

[0066] In step S2.2 of the preparation method, the 8 layers of impregnated fiber fabric are pressed together using pressing rollers to obtain a pre-fixed core layer. The preheating temperature of the pressing rollers is 115°C, the spacing is about 3.0 mm, and a pre-fixed core layer with a thickness of about 3.0 mm is obtained.

[0067] The other steps are the same as in Example 1, resulting in the port insulation composite structure of Example 2.

[0068] Example 3 The difference between Example 3 and Example 1 in the port insulation composite structure lies in the thickness of each layer and the total thickness. In Example 3: i) The first outer layer, approximately 0.5 mm thick; ii) Compression-resistant core layer, approximately 4.0 mm thick; iii) The second outer layer has the same formula and thickness as the first outer layer.

[0069] The total thickness of the insulating composite structure for ports in Example 3 is approximately 5.0 mm.

[0070] In step S2.2 of the preparation method, 12 layers of impregnated fiber fabric are pressed together using pressing rollers to obtain a pre-fixed core layer. The preheating temperature of the pressing rollers is 120°C, the spacing is about 4.0 mm, and a pre-fixed core layer with a thickness of about 4.0 mm is obtained.

[0071] The other steps are the same as in Example 1, resulting in the port insulation composite structure of Example 3.

[0072] Example 4 The difference between Example 4 and Example 1 in the port insulation composite structure lies in the thickness of each layer and the total thickness. In Example 4: i) The first outer layer, approximately 1.5 mm thick; ii) Compression-resistant core layer, approximately 1.0 mm thick; iii) The second outer layer has the same formula and thickness as the first outer layer.

[0073] The total thickness of the insulating composite structure for ports in Example 4 is approximately 4.0 mm.

[0074] In step S2.2 of the preparation method, the three layers of impregnated fiber fabric are pressed together using pressing rollers to obtain a pre-fixed core layer. The preheating temperature of the pressing rollers is 105°C, the spacing is about 1.0 mm, and a pre-fixed core layer with a thickness of about 1.0 mm is obtained.

[0075] The other steps are the same as in Example 1, resulting in the port insulation composite structure of Example 4.

[0076] Example 5 The difference between Example 5 and Example 1 is that Example 5 directly uses pressing rollers to squeeze and pre-cure the two-stage impregnated fiber fabric, specifically including: S2. The alkali-free glass fiber fabric is subjected to double-sided online treatment by atmospheric plasma, and then the fiber fabric is impregnated twice with core layer adhesive. The fiber fabric is conveyed at a speed of 5m / min. Between the two impregnations, a set of rollers is used to assist the impregnation by roller pressing. Five layers of impregnated fiber fabric are pressed together using pressing rollers to obtain a pre-cured core layer. The pressing rollers are preheated at 110°C and spaced about 1.50 mm apart, resulting in a pre-cured core layer with a thickness of about 1.50 mm and a pre-curing degree of about 30%.

[0077] The other steps are the same as in Example 1, resulting in the port insulation composite structure of Example 5.

[0078] Example 6 The difference between Example 6 and Example 1 is that in the preparation method, the fillers were not pretreated on the surface and the adhesive solutions of each layer were directly prepared.

[0079] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that conductive fillers are not used in the first and second outer layers of the insulating composite structure.

[0080] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the pressure-resistant core layer of the insulating composite structure does not use conductive filler.

[0081] Test methods and results The port insulation composite structures prepared in Examples 1-6 and Comparative Examples 1-2 were subjected to performance tests under dry conditions. The test results are shown in Table 1.

[0082] Table 1

[0083] The room temperature volume resistivity of the insulating composite structure in Examples 1-6 of this invention is 6 × 10⁻⁶. 6 ~6×10 8 Ω·cm, with a volume resistivity of 1×10 at 85℃. 6 ~2×10 8 Ω·cm, with suitable insulation properties for port use; room temperature compressive strength not less than 260MPa (ASTM D695), preferably above 285MPa, and flexural strength not less than 400MPa (GB / T1449-2005 three-point bending test), preferably above 415MPa.

[0084] Application Examples 1-1 to 1-8 The insulating composite structure samples of Examples 1-6 (corresponding to Application Examples 1-1 to 1-6) and Comparative Examples 1-2 (corresponding to Application Examples 1-7 and 1-8) were cut and punched to obtain annular nut insulating washers. These nut insulating washers were then installed into the ship-to-shore connection pipe assembly. The pipe insulation assembly is shown in the attached document. Figure 3 and Figure 5 This includes flange assembly, connecting bolts, connecting nuts, nut insulating washers, and heat-shrink insulating sleeves; The connecting bolts (M20, grade 8.8 bolts) are used, with one end passing through the flange assembly and locked in place by the connecting nut. The heat-shrinkable insulating sleeve covers the bolt surface inside the flange assembly, isolating the flange assembly from the connecting bolts along the bolt axis. The heat-shrinkable insulating sleeve is made of commercially available double-layer polyolefin material, with an outer layer of soft cross-linked polyethylene and an inner layer of polyolefin hot melt layer (shrinkage temperature approximately 120-125℃, operating temperature below 125℃, fire rating VW-1). Two sets of nut insulating washers are respectively fitted onto both ends of the connecting bolts and abut against the outer side of the flange assembly. The flange assembly includes two flanges located at different pipe ends, and a commercially available insulating sealing washer sandwiched between the two flanges.

[0085] The component assembly process includes: Place the heat-shrinkable insulating sleeve on the corresponding position of the connecting bolt, and heat it evenly with a hot air gun until it is completely shrunk and tightly wrapped. After the connecting bolts are covered, insert the nuts and insulating washers into the flange assembly connection holes, then put on the nuts and insulating washers again, and tighten with the corresponding connecting nuts to complete a set of connections. Complete all locking connections on the flange assembly sequentially to complete the pipe insulation connection.

[0086] Tighten the M20, 8.8 grade connecting bolts to normal torque. After five tightening / loosening tests, refer to the attached document. Figure 6-7 The nut insulating washer of Example 1 had a few friction marks on its surface, and no cracks were found on the surface and sides. The nut insulating washers of Examples 2-6 were basically similar in terms of friction and cracks. The nut insulating washer of Comparative Example 1 had large and deep scratches on its surface, and the nut insulating washer of Comparative Example 2 had a few cracks on its sides. Cracks will make the nut insulating washers used in port environments prone to accumulating dirt and accelerating corrosion.

[0087] Application Example 2 See Figure 4 Based on Application Example 1-1, the insulating composite structure sample of Example 2 is cut and punched to obtain an annular flange insulating gasket. This flange insulating gasket is used in a flange assembly, which includes two flanges located at different pipe ends and a flange insulating gasket assembly sandwiched between the two flanges. The flange insulating gasket assembly includes a flange gasket and flange insulating gaskets located on both sides of the flange gasket and abutting against the inner surface of the corresponding flange. The flange gasket is a commercially available stainless steel strip-flexible graphite metal spiral wound gasket, which is a semi-metallic gasket with excellent comprehensive properties such as high temperature resistance and corrosion resistance.

[0088] The pipe insulation connection structure of each application example was tested at room temperature using an ohmmeter (with contacts connected to two flanges respectively). Five insulation components were tested for each application example, and the results are shown in Table 2.

[0089] Table 2

[0090] Tests using multiple application examples show that Application Examples 1-1 to 1-6 and Application Example 2 can all provide an insulation resistance value of 1 to 2.5 MΩ between connected pipes. Relatively speaking, Application Examples 1-6, which used the insulation composite structure of Examples 1-6, exhibited relatively stable insulation performance, with insulation resistance deviations of less than 1.0 MΩ in multiple tests. In particular, the insulation resistance deviation of Application Example 1-4 was less than 0.5 MΩ, ensuring long-term application stability and safety. Application Examples 1-7, which do not use conductive fillers in the outer layer, achieved insulation resistance values ​​approaching 2.5 MΩ in some samples due to the diffusion of carbon fiber particles in the core layer to form conductive channels. However, the large fluctuations in insulation resistance cannot guarantee long-term safety, and the lack of reinforcing wear resistance from the outer filler means that their mechanical and surface properties cannot meet the requirements for long-term high-strength locking. In Application Examples 1-8, since the core layer does not use conductive carbon fiber particles to form an insulating tape, although a small number of conductive particles in the outer layer migrate during the co-curing process, the overall insulation resistance value is too high and cannot meet the safety requirements of port pipeline connections. Application Examples 1-7 and 1-8 are similar to the usual insulation structures. If they are to be used, a bypass resistor must be added for static electricity discharge.

[0091] By combining Example 1 (nut insulating washer) and Example 2 (flange insulating washer) in Application Example 2, the insulation resistance value between the connected pipes meets the requirements. Using individual or multiple combinations of samples from the various embodiments of this invention can generally meet the insulation requirements, providing a wide range of choices for different thicknesses and insulation properties. Furthermore, the material selection for flange gaskets can be expanded from existing insulating gaskets to commercially available general-purpose sealing gaskets made of pressure-resistant, wear-resistant, high-temperature resistant, acid- and alkali-resistant metals and / or carbon-containing materials.

[0092] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. An insulating composite structure for use in ports, characterized in that, In order, they include: i) The first outer layer, with a thickness of 0.5 to 1.5 mm, includes an epoxy resin matrix and a first filler dispersed therein; ii) The compressive core layer is a fiber-reinforced epoxy composite layer with a thickness of 1.0–4.0 mm, comprising an epoxy resin matrix, a second conductive filler dispersed therein, and a number of fiber fabrics; the mass of the fiber fabrics accounts for 45–65% of the total mass of the compressive core layer; The fiber fabric is laid flat along the compressive core layer, and the pore size of the fiber fabric is 10-30 μm; At least a portion of the second conductive filler is inserted into the fiber fabric. The second conductive filler comprises carbon fiber particles with a diameter of 5–10 μm and a length of 0.1–0.5 mm. The mass of the carbon fiber particles accounts for 5–10% of the total mass of the compressive core layer. iii) The second outer layer, with a thickness of 0.5 to 1.5 mm, includes an epoxy resin matrix and a third filler dispersed therein; The first filler and the third filler respectively include at least one of conductive carbon particles, silicon carbide micro powder, silicon carbide whiskers, and conductive titanate particles; The first outer layer and the second outer layer also include antioxidants and light stabilizers, respectively. TiO2 nanoparticles are added to the light stabilizers in the first and second outer layers for pre-compounding. The amount of TiO2 nanoparticles is 1-10% of the mass of the light stabilizer. The first outer layer, the pressure-resistant core layer, and the second outer layer are molded into a single structure. The volume resistivity of the insulating composite structure used in ports is 6×10⁻⁶ at 20–30℃. 6 ~6×10 8 Ω·cm; volume resistivity at temperatures above 80℃ is 1×10 Ω·cm 6 ~2×10 8 Ω·cm.

2. The port insulation composite structure as described in claim 1, characterized in that, The fiber fabric of the pressure-resistant core layer includes at least one of glass fiber fabric, quartz fiber fabric, and aramid fiber fabric.

3. The port insulation composite structure as described in claim 1 or 2, characterized in that, The fiber fabric, the first filler, the second conductive filler, and the third filler undergo surface treatment, which is performed using a coupling agent.

4. A method for preparing a port insulating composite structure according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Prepare the adhesive solutions for each layer: The second conductive filler is uniformly dispersed in epoxy resin to obtain the core layer adhesive. The first filler is uniformly dispersed in epoxy resin to prepare the first outer layer adhesive; The third filler is uniformly dispersed in epoxy resin to prepare the second outer layer adhesive; S2. The fiber fabric is impregnated with core layer adhesive at least twice, and the impregnated fiber fabric is extruded and pre-cured by preheated rollers to obtain a pre-cured core layer. S3. Place the pre-cured core layer in the mold, and use a vacuum introduction process or a resin transfer molding process to introduce the first outer layer adhesive and the second outer layer adhesive into the mold, respectively or simultaneously, to form an outer layer covering the upper and lower surfaces of the pre-cured core layer. S4. Perform stepped heating and co-curing to form the pre-cured core layer and outer layer into an integrated port insulation composite structure.

5. The preparation method according to claim 4, characterized in that, In step S2, the pre-cured fiber fabric is extruded and pre-cured using preheated rollers to obtain a pre-cured core layer, including the following steps: S2.1 At least two sets of preheated rollers are arranged sequentially to form a roller group to extrude a single-layer impregnated fiber fabric, wherein: The first pair of rollers is preheated to 60–80℃ with a spacing of 0.40–0.80 mm. The second pair of rollers has a preheating temperature of 90–110℃ and a spacing of 0.20–0.50 mm. S2.2 Pressing a predetermined number of layers of impregnated fiber fabric is performed using pressing rollers to obtain a pre-fixed core layer. The preheating temperature of the pressing rollers is 100-120℃, and the spacing is 1.00-4.0mm.

6. The preparation method according to claim 4 or 5, characterized in that, The preparation method includes at least one of the following processes: (1) Before being dispersed in epoxy resin, the first filler, the second conductive filler and the third filler are treated with silane coupling agent; (2) The single or double sides of the fiber fabric are treated online by atmospheric plasma, and then enter the first impregnation at the first conveying speed V1 and the second impregnation at the second conveying speed V2, wherein 1m / min≤V2≤V1≤10m / min; (3) Between at least two impregnations, the fiber fabric is subjected to roller-assisted impregnation using at least one set of rollers; (4) After cutting the pre-solidified core layer and performing double-sided atmospheric plasma treatment, it is stacked in the mold.

7. The preparation method according to claim 4 or 5, characterized in that, In step S4, the stepped temperature co-curing includes the following steps: S4.1 First-stage heating: heat to T1, and simultaneously pressurize to (40%~60%)×P, where T1 is 80~100℃ and P is 0.1~0.5MPa, and hold at the temperature and pressure for 15~30min; S4.2, Second-stage heating, heating to T2, T2 is T1+ (20℃~50℃), simultaneously pressurizing to P, holding at temperature and pressure for 15~30min; S4.3, three-stage heating, heating to T3, T3 is T2+ (10℃~40℃), keeping the pressure P constant, heat and pressure holding for 10~30min, to obtain an integrated port insulation composite structure.

8. An insulating component, characterized in that, Includes flange assembly, connecting bolts, connecting nuts, nut insulating washers, and heat shrink insulating sleeves; One end of the connecting bolt passes through the flange assembly and is locked in place by the connecting nut; The heat-shrinkable insulating sleeve shall at least cover the surface of the bolts located within the flange assembly. Two sets of nut insulating washers are respectively fitted onto both ends of the connecting bolt and abut against the outer side of the flange assembly. The nut insulating washers include the port insulating composite structure as described in any one of claims 1-3, or the port insulating composite structure prepared by the preparation method described in any one of claims 4-7. The insulation component provides an insulation resistance value of 1 to 2.5 MΩ between the connecting pipes.

9. The insulating component as claimed in claim 8, characterized in that, The flange assembly includes two flanges located at different pipe ends, and a flange insulating gasket assembly sandwiched between the two flanges. The flange insulating gasket assembly includes a flange gasket and flange insulating gaskets located on both sides of the flange gasket and abutting against the inner surface of the corresponding flange. The flange insulating gaskets include the port insulation composite structure.

Images