Mountain photovoltaic cable joint waterproof sealing preparation process

Abstract

The invention discloses a waterproof sealing preparation process for a mountain photovoltaic cable joint, and relates to the technical field of cable preparation, and the waterproof sealing preparation process comprises the following steps: pretreating the surface of a cable joint area; coating an interface enhancing primer; installing a mold and pouring an inner-layer sealant; demolding and trimming the sealing body; winding the stress buffer and mechanical enhancement layer; coating outer layer glue and installing a shape memory sheath; the activation sheath is heated to cure it and apply compressive stress. According to the invention, through the specific bi-component reactive elastic sealant, in-situ pouring and curing are carried out at the joint to form a main body sealing body with a high-elasticity inner layer and high adhesion; the outer sleeve is provided with a novel thermoset composite material sheath with a shape memory effect and continuous radial shrinkage force, and the sheath can generate lasting and uniform radial pressure stress on an internal sealing body after being activated at a specific temperature, so that interface pressure attenuation possibly caused by temperature change, material aging or vibration is compensated, and dynamic and long-term sealing guarantee is realized.

Description

Technical Field

[0001] This invention belongs to the field of cable manufacturing technology, and in particular relates to the manufacturing process of waterproof sealing for mountain photovoltaic cable joints. Background Technology

[0002] Photovoltaic cable joints are critical connection points in photovoltaic power generation systems, and their sealing reliability directly affects the long-term stability and safety of the system. Mountainous environments are characterized by large diurnal temperature variations, strong ultraviolet radiation, frequent mechanical vibrations, and high humidity, placing stringent requirements on the waterproofing, weather resistance, vibration resistance, and high and low temperature cycling performance of cable joints.

[0003] In existing technologies, heat shrink tubing, waterproof tape, potting compound, or mechanical seal boxes are commonly used for joint protection. However, these methods have the following limitations: heat shrink tubing relies on uniform heating, making installation difficult in windy mountainous environments, and it is prone to aging and cracking under long-term UV exposure; waterproof tape has uneven sealing pressure, easily creating gaps, and it is prone to loosening under temperature cycling; potting compound has high hardness after curing, making it difficult to adapt to joint deformation caused by thermal expansion and contraction and vibration, easily leading to internal stress cracks; mechanical seal boxes have complex structures, high costs, and require high installation precision. Therefore, the following solutions are proposed to address these problems. Summary of the Invention

[0004] The purpose of this invention is to provide a waterproof sealing process for mountain photovoltaic cable joints. Through the composite structure of an inner high-elasticity sealing body formed by in-situ casting and an outer shape memory sheath that can apply continuous radial clamping force after thermal activation, an effective interface sealing pressure can be dynamically maintained throughout the entire life cycle of the cable joint. This solves the problem that existing sealing technologies cannot guarantee long-term waterproof reliability in harsh environments such as mountains due to the decay of initial sealing pressure caused by material aging, temperature cycling and mechanical vibration.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: This invention relates to a waterproof sealing process for mountain photovoltaic cable joints, comprising the following steps: Step S1, Joint Area Pretreatment: Clean, roughen and preheat the surfaces of the electrically connected photovoltaic cable joints and adjacent cables; Step S2: Apply an interface-enhancing primer: Apply a layer of special primer to the treated surface and allow it to age; Step S3: Install the mold and pour the inner layer sealant: Install a temporary mold on the outside of the joint, pour two-component high elastic sealant into the mold, let it cure in situ to form an inner elastic seal, and then demold. Step S4, Winding the buffer reinforcement layer: On the outer surface of the inner elastic seal body, self-adhesive rubber tape and fiber-reinforced webbing are tightly wound in sequence to form a composite winding layer; Step S5, Apply adhesive and install the outer sheath: Apply adhesive to the surface of the composite winding layer, and then insert the uncured shape memory thermosetting composite material sheath; Step S6, Thermal Activation and Final Curing: The outer sheath is uniformly heated so that it undergoes thermal curing while activating the internal shape memory effect, thereby generating continuous radial compressive stress on the internal sealing structure. After cooling, a composite waterproof sealing structure is formed.

[0006] Furthermore, the preprocessing described in step S1 specifically includes: Use an organic solvent cleaner to thoroughly clean the cable joint and the surface of the cable outer sheath within a certain range on both sides; The cleaned area is then mechanically sanded to roughen the surface, and all sanding dust is then removed. Use hot air equipment to preheat the sanded area evenly to remove moisture and increase the surface temperature.

[0007] Furthermore, the special primer mentioned in step S2 is a silane-modified resin base coating agent, which includes silane-modified resin, adhesion promoter and nano thickener.

[0008] Furthermore, the two-component high-elasticity sealant described in step S3 is composed of two components, A and B, mixed in a certain proportion. Component A contains a polyorganosiloxane base polymer with reactive end groups, reinforcing fillers, and stabilizing agents, while component B contains a crosslinking agent and a catalyst.

[0009] Furthermore, after curing, the two-component high-elasticity sealant forms a silicone rubber seal with permanent elasticity, which forms a chemical and physical bond with the cable surface after primer treatment.

[0010] Furthermore, the self-adhesive rubber tape mentioned in step S4 is a butyl rubber self-adhesive tape, and the fiber-reinforced webbing is a polyester fiber webbing impregnated with elastic resin; during winding, appropriate tension is applied to both materials respectively, and the specified overlap ratio is ensured.

[0011] Furthermore, the shape memory thermosetting composite material sheath described in step S5 is an uncured prepreg tube, which comprises a thermosetting resin matrix, radially oriented high-modulus fibers, and a thermotropic shape memory polymer material.

[0012] Furthermore, the thermal activation process described in step S6 is as follows: the joint area covered by the sheath is uniformly heated to a specific temperature and maintained for a period of time. During this process, the resin matrix of the sheath undergoes a thermosetting reaction, and the internal shape memory material is activated, guiding the sheath to generate continuous radial shrinkage compressive stress.

[0013] Furthermore, the heating is carried out using an annular hot air heating device or an infrared heating blanket. After heating is completed, the heating is allowed to cool naturally to room temperature, so that the sheath can be cured and shaped and the radial compressive stress can be locked.

[0014] Furthermore, after step S6 is completed, sealant should be used to seal the overlap between the two ends of the outer sheath and the cable outer sheath to form a waterproof skirt.

[0015] The present invention has the following beneficial effects: This invention achieves multiple beneficial effects through a composite structure design of an in-situ molded elastic sealing body and a heat-activated shape memory sheath. The inner elastic sealing body can effectively adapt to joint structural deformation and thermal expansion and contraction, ensuring the reliability of the basic seal. After heat activation and curing, the outer sheath can generate a uniform and lasting radial clamping force on the sealing body, actively compensating for the attenuation of sealing pressure that may be caused by material aging or environmental cycles, thereby improving the long-term stability of the seal. This composite system enhances the joint's resistance to harsh mountain environments such as mechanical vibration, temperature shock, and ultraviolet radiation. At the same time, the on-site casting and medium-temperature activation process is easy to implement and has good construction adaptability to complex terrain and irregular joint structures. Overall, this process improves the reliability and durability of photovoltaic cable joint protection.

[0016] 2. This invention.

[0017] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the process for preparing the waterproof seal of the mountain photovoltaic cable joint according to the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1As shown, this invention provides a waterproof sealing process for mountain photovoltaic cable joints, comprising the following steps: Step S1: Pre-treatment of the joint area Step S11: Confirm that the cable connectors are reliably connected in accordance with electrical specifications (e.g., using piercing clamps, crimping, or welding). Step S12: Thoroughly clean the joint area and the cable outer sheath surface within a range of at least 150 mm on both sides using a special cleaning agent (e.g., a mixed solvent of anhydrous ethanol and acetone in a volume ratio of 3:1). During cleaning, wipe repeatedly along the cable axis at least three times until there are no visible oil stains, dust, or release agent residues on the surface. After cleaning, wait for more than 60 seconds to allow the solvent to evaporate completely. Step S13: Using an electric belt sander equipped with 80-100 grit sandpaper or a manual fine polishing tool, lightly roughen the surface of the cable joint metal parts (if any) and the cable insulation layer and outer sheath within 100mm on both sides; the polishing direction should be perpendicular to the cable axis at a 30-45 degree angle, the purpose of which is to remove the surface gloss layer and increase the surface area without damaging the cable insulation; after polishing, remove all polishing dust with a dry, lint-free cloth; Step S14: Use an industrial hot air gun with a power of not less than 1000W to preheat the pre-treatment area evenly with hot air at 80-120℃ for 2-3 minutes. The purpose of preheating is to remove any moisture that may be adsorbed on the surface and to improve the wettability and leveling properties of the subsequent sealing material. After preheating, the surface temperature should be maintained at 40-50℃.

[0022] Step S2: Apply a special interface-enhancing primer Step S21: Take a single-component silane-modified polyether resin primer specially formulated for this process; the main components and weight ratio of the primer are: 100 parts of silane-modified polyether resin (terminated siloxane), 3-5 parts of adhesion promoter (such as γ-aminopropyltriethoxysilane), 1-2 parts of nano-sized fumed silica (thickening and anti-sagging), and 10-15 parts of anhydrous solvent (such as isopropanol). Step S22: After thoroughly shaking the primer, apply it evenly to the entire area pretreated in Step 1 using a brush or non-woven fabric to ensure the formation of a continuous, bubble-free, and uncoated transparent film with a wet film thickness of approximately 30-50 micrometers. Step S23: After coating, allow the coating to stand and age for 5-8 minutes at an ambient temperature not lower than 15°C to allow the solvent in the primer to evaporate and to form a preliminary chemical bond with the substrate surface.

[0023] Step S3: Install the detachable temporary mold and pour the inner layer of elastic sealant. Step S31: Select a transparent flexible silicone mold with tapered tightening openings at both ends according to the size of the connector; the inner diameter of the mold is 10-15mm larger than the maximum outer diameter of the connector, and the length covers the entire connector and extends outward by at least 50mm; the mold is symmetrically divided into two halves along the axial direction, and the edges are equipped with sealing strips and quick-locking buckles. Step S32: Spray a thin layer of release agent (such as modified silicone release agent) evenly on the inner wall of the mold, let it stand for 1 minute, and then wipe it until only a trace of residue remains; Step S33: Tightly fasten the two halves of the mold to the outside of the joint, ensuring that the joint is located in the center of the mold, and lock it with the locking buckle. Check that there are no obvious gaps at the joint. Step S34: Prepare a two-component high-elasticity sealant (components A and B); component A mainly contains: 100 parts of hydroxyl-terminated polydimethylsiloxane (viscosity 5000-8000cps), 20-30 parts of reinforcing nano-calcium carbonate, 1-2 parts of thixotropic agent (hydrogenated castor oil), 0.5-1 parts of ultraviolet absorber (benzotriazole), and 0.3-0.5 parts of antioxidant (hindered phenol); component B is a complex of crosslinking agent and catalyst, mainly containing: 8-12 parts of methyltrimethoxysilane crosslinking agent, 0.5-1 parts of organotin catalyst (such as dibutyltin dilaurate), and 1-2 parts of adhesion promoter (epoxysilane); the mixing volume ratio of components A and B is 10:1; Step S35: Using a two-component dynamic mixing tube (at least 20cm in length, static mixer) and a special glue gun, inject the well-mixed sealant into the pre-reserved pouring hole at the top of the mold at a steady speed until the sealant continuously overflows from the overflow hole on the lower side of the mold, indicating that the cavity is completely filled without air bubbles; the pouring process should be continuous and should not be interrupted. Step S36: After pouring, allow to stand and cure for 4-6 hours at an ambient temperature of 25±5℃. During this period, the sealant cures through moisture catalysis and condensation reaction, forming a soft, dense, and permanently elastic silicone rubber sealant that forms a chemical and physical bond with the cable surface after primer treatment.

[0024] Step S4, Demolding and Trimming Step S41: After curing, loosen and carefully remove the outer silicone mold; inspect the in-situ molded elastic seal, its surface should be smooth and flat, without shrinkage cavities, cracks or peeling at the cable interface; Step S42: Use a blunt plastic scraper or a special trimming tool to remove the small amount of glue nodules generated at the pouring port and overflow port, so that the two ends of the seal body can smoothly transition with the outer sheath of the cable, and the length of the transition area should not be less than 20mm.

[0025] Step S5: Winding stress buffer and reinforcement layer Step S51: Starting from one end of the elastic seal, tightly wrap a layer of uncured butyl rubber self-adhesive tape with an overlap ratio of 55-60% (i.e., the width of the next wrap covers more than half of the width of the previous wrap); the butyl rubber tape should be 30mm wide and 1.0-1.5mm thick, and a constant tension of about 5N should be applied when wrapping. Step S52: On the outer layer of the butyl rubber tape, a layer of high-strength, corrosion-resistant polyester fiber reinforced webbing is wound at a lamination rate of 50-55%; the webbing may be pre-impregnated with a compatible elastic resin; the tension during winding may be slightly increased to 8-10N to provide a moderate circumferential restraint force; this composite winding layer, as a stress buffer and mechanical reinforcement layer, can disperse the pressure of the outer sheath and resist possible mechanical scratches.

[0026] Step S6: Apply outer layer adhesive sealant and install shape memory sleeve. Step S61: Apply a layer of two-component high-elasticity sealant (which can be used as an outer layer) with a thickness of about 1 mm evenly to the surface of the composite winding layer; this layer of sealant mainly serves to bond and provide secondary sealing. Step S62: Immediately insert the pre-prepared shape memory thermosetting composite material sleeve onto the outside of the uncured outer adhesive layer; the sleeve is an uncured prepreg tube, mainly composed of the following components: 100 parts of saturated polyester resin or modified epoxy resin matrix, 60-80 parts of radially oriented high modulus glass fiber or carbon fiber tow, 10-15 parts of thermotropic shape memory polymer microspheres (trigger temperature 80-90℃), and anti-UV aging additives; the inner diameter of the sleeve is slightly smaller than the outer diameter of the current connector assembly (difference of about 2-3mm), requiring a little force to insert, thereby ensuring initial adhesion with the outer adhesive layer; Step S63: The two ends of the sheath should cover the outer sheath of the cable, with a coverage length of not less than 40mm; temporarily fix the two ends of the sheath with high-temperature resistant tape.

[0027] Step S7, heat-activated sheath and final curing Step S71: Use a ring-shaped hot air heating device with precise temperature control or an infrared heating blanket with a specific power to heat the entire sheath area evenly; within 10 minutes, raise the temperature from room temperature to 85±2℃ at a uniform rate, and maintain this temperature for 15-20 minutes. Step S72: During this heating process, the resin matrix inside the sheath begins to cross-link and cure (thermosetting reaction). At the same time, the thermally induced shape memory microspheres expand due to heat, and the radially oriented fibers generate additional inward shrinkage force due to the decrease in the viscosity of the resin system. This process allows the sheath to be cured and shaped while applying a continuous and uniform radial compressive stress to the internal elastic seal and winding layer. Step S73: After the heating activation is complete, turn off the heat source and allow the joint to cool slowly to room temperature under natural conditions; during the cooling process, the sheath is fully cured and the radial compressive stress applied to it is "locked"; Step S74: Finally, at the overlap between the two ends of the sheath and the outer sheath of the cable, the above-mentioned two-component high-elasticity sealant is used for final sealing to form a smooth waterproof skirt, thus completing the preparation of the entire sealing system.

[0028] The specific application of this embodiment is as follows: Example 1: Standard process applied to a typical 4mm² photovoltaic cable joint This embodiment demonstrates the complete process of applying the process of the present invention to the most common 4mm² photovoltaic cable butt joint (such as MC4 compatible joint) in mountain photovoltaic arrays; Step S1: Pre-treatment of the joint area Step S11: Confirm that the two 4mm² photovoltaic cables have been electrically connected through standard crimped metal connectors and that the internal insulation layer has been installed; Step S12: Use a mixture of anhydrous ethanol and acetone in a volume ratio of 3:1 to clean the connecting pipe and the outer sheath of the cable on both sides for 150 mm each (usually cross-linked polyolefin); wipe it repeatedly along the axial direction four times with a lint-free cloth; Step S13: Using a pen-type sander with 100-grit sandpaper, sand the cleaned area at a 45° angle, focusing on sanding the cable outer sheath to remove shine; blow away all dust with dry compressed air. Step S14: Use a 1200W hot air gun to preheat the surface with 100°C hot air for 3 minutes at a distance of about 15cm, so that the surface temperature rises to about 45°C. Step S2: Apply a special interface-enhancing primer Step S21: Take a primer with the following proportions: 100 parts of silane-modified polyether resin, 4 parts of γ-aminopropyltriethoxysilane, 1.5 parts of nano-fumed silica, and 12 parts of isopropanol. Step S21: Use a small brush to evenly apply the primer to the entire preheated area to form a continuous wet film; Step S21: Let it stand and age at 20°C for 7 minutes. After the solvent evaporates, a slightly sticky transparent coating will form on the surface. Step S3: Install the mold and pour the inner layer of elastic sealant. Step S31: Select a transparent two-part silicone mold with an inner cavity diameter of 25mm and a length of 200mm, spray release agent inside, and then fasten and lock it onto the connector. Step S32: Prepare the inner layer sealant; Component A: 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 6000 cps, 25 parts of nano-calcium carbonate, 1.5 parts of thixotropic agent, 0.8 parts of ultraviolet absorber, and 0.4 parts of antioxidant; Component B: 10 parts of methyltrimethoxysilane, 0.8 parts of dibutyltin dilaurate, and 1.5 parts of epoxy silane; Inject the sealant into the glue gun through a 20cm long static mixing tube at a volume ratio of A:B = 10:1; Step S33: Slowly inject the mixed adhesive from the top gating hole of the mold until the adhesive overflows steadily from the bottom overflow hole, then stop pouring; Step S34: Allow to cure at room temperature (25°C) for 5 hours; Step S4, Demolding and Trimming Step S41: Open the latch, carefully separate and remove the silicone mold to obtain a smooth, matte, light gray elastic seal with no visible gaps at the junction with the cable; Step S42: Use a plastic scraper to smooth out any lumps at the gate and overflow outlet to create a smooth transition; Step S5: Winding stress buffer and reinforcement layer Step S51: Wrap a 30mm wide and 1.2mm thick butyl rubber self-adhesive tape around the seal with an overlap of approximately 58%, maintaining a tension of approximately 5N; Step S52: On its outer layer, a layer of pre-impregnated elastic polyurethane polyester fiber webbing is wound around with an overlap ratio of about 52% and a tension of about 9N. Step S6: Apply outer adhesive and install shape memory sleeve Step S61: Apply a layer of two-component elastic sealant of the same type (outer layer adhesive) with a scraper evenly on the surface of the wrapping layer, with a thickness of about 1 mm. Step S62: Immediately insert an uncured shape memory sheath (made of radial glass fiber / saturated polyester resin matrix containing 12 parts of thermotropic shape memory microspheres) with an inner diameter of 19 mm and a length of 220 mm; the sheath needs to be slightly expanded to fit, and each end covers the outer sheath of the cable by about 45 mm; temporarily fix it with high temperature tape; Step S7, heat-activated sheath and final curing Step S71: Using a ring-shaped hot air heater, heat the sheath area to 85°C at a rate of approximately 8°C / min and maintain this temperature for 18 minutes; Step S72: During heating, the sheath will shrink slightly and adhere more tightly to the outer adhesive layer; stop heating and allow it to cool naturally to room temperature. Step S73: At the junctions of the sheath and the cable at both ends, use a small amount of the same type of sealant to seal the junctions, forming a smooth, conical, waterproof skirt. Results: The completed joint seal is robust and elastic; it has been tested and found to be IP68 (1 meter water depth, 72 hours), with no cracking or leakage after temperature cycling from -40℃ to +85℃, and can withstand long-term ultraviolet radiation and simulated mechanical vibration; the shape memory sleeve provides a perceptible and continuous clamping force.

[0029] Example 2: Process applied to large-size (35mm²) cable branch joints This embodiment demonstrates the adaptability of the present invention's process to larger and more complex joint structures; Step S1: Pre-treatment of the joint area Step S11: Pre-treat the T-shaped branch insulation piercing clamp joint formed by the 35mm² cable and two 16mm² cables; the cleaning range is expanded to 200mm on both sides of the joint. Step S12: Use an electric sander equipped with 80-grit sandpaper to carefully and evenly roughen the complex contours at the branch points; Step S13: Use a high-power hot air gun to preheat the area in sections to ensure that the surface temperature of the entire complex joint rises to about 50°C. Steps S2 to S4: Primer application, mold pouring and finishing 1. The primer formulation and coating method are the same as in Example 1, but the coating area is larger; 2. Custom-made split silicone molds are made according to the irregular three-dimensional shape of the joint; the casting process is carried out in steps from multiple angles to ensure that the cavity is completely filled and there are no air pockets. 3. The amount of nano-calcium carbonate in component A of the inner sealant has been increased to 30 parts to obtain higher strength and extend the curing time to 6.5 hours; 4. After demolding, a highly elastic inner sealing body that perfectly conforms to the complex joint contour is obtained; Step S5: Winding stress buffer and reinforcement layer Due to the large size and irregular shape of the joint, a combination of butyl rubber tape and polyester webbing of two widths (30mm and 50mm) was used for winding, and reinforcement was carried out in stress concentration areas such as the branch root. Steps S6 to S7: Install the protective sleeve and perform thermal activation 1. Since the connector is not cylindrical, the shape memory sleeve installed after the outer layer is coated with adhesive is a thermosetting composite material shell (not a simple tubular shape) pre-formed according to the shape of the connector. Its inner wall is pre-set with guide ribs to ensure accurate installation position. 2. The thermal activation process uses a flexible infrared heating blanket to wrap the entire joint and heat it to 83°C at a gentler rate (5°C / minute) and maintain it for 25 minutes to ensure that the heat is evenly transferred to the entire irregular sheath, triggering its uniform shrinkage and curing; Results: A complete composite sealing system was successfully constructed for complex, large-sized branch joints; tests showed that the seal not only withstood harsh environmental aging tests, but also had higher tear resistance and gripping force on each branch cable than traditional potting solutions, effectively preventing loosening of the sealing interface due to cable weight or wind vibration.

[0030] Example 3: Process variant, employing a rapid curing system to adapt to low-temperature environments. This embodiment demonstrates the adaptability of material formulation and process parameters when constructing at lower ambient temperatures (e.g., 10-15°C). Steps S1 to S2: Pretreatment and Primer The steps are the same as in Example 1, but the preheating temperature is increased to 120°C to compensate for the lower substrate temperature; Step S3: Install the mold and pour the inner layer of elastic sealant (fast-curing type). 1. The inner sealant adopts a fast-curing formula; some highly active polysiloxane segments are added to component A; the crosslinking agent in component B is increased to 12 parts, and a compound catalyst (organotin and titanate composite) is used, with the total catalyst content increased to 1.5 parts; 2. The working time after mixing is shortened to about 15 minutes; after pouring, use a portable warm air insulation cover under the joint to maintain the local ambient temperature at about 30℃. 3. Under these conditions, the gel time of the inner layer adhesive is approximately 40 minutes, and it reaches the release strength in 3 hours; Steps S4 to S6: Demolding, winding, and installing the protective sleeve The steps are similar to those in Example 1, but all operations must be carried out compactly under heat preservation conditions; Step S7, heat-activated sheath and final curing 1. Due to the low ambient temperature, the initial heating rate during thermal activation is slowed down, but the final activation temperature is increased to 88℃, and the holding time is extended to 22 minutes to ensure that the resin of the shape memory sleeve is fully cured and the microspheres are fully activated. 2. After activation, allow it to cool slowly inside the insulation cover until it approaches ambient temperature before removing it; Results: The entire sealing process was successfully completed in a simulated 15°C mountain low-temperature environment; the performance test results of the prepared joint were not significantly different from those of the sample prepared under standard conditions in Example 1, proving the adaptability and reliability of the process of the present invention within a certain construction window temperature range.

[0031] Comparative Example 1: Using traditional heat shrink tubing instead of shape memory sleeve This comparative example simulates an alternative that might be considered "simple": using only a high-performance inner layer sealant, but employing a waterproof heat shrink tubing with hot melt adhesive as the outermost layer of protection, to replace the shape memory sheath composite structure of the present invention. Steps: The operation steps from "Step S1" to "Step S5" are exactly the same as in Example 1; in "Step S6", the outer layer adhesive coating and the installation of the shape memory sleeve are cancelled and replaced with: 1. Select a 20mm inner diameter double-walled waterproof heat shrink tubing with a nominal weather-resistant finish and thick-walled hot melt adhesive. 2. Place the heat shrink tubing over the outer layer of the wrapping layer and use a heat gun or blowtorch to heat and shrink it evenly from the middle to both ends; the heat shrink tubing tightly wraps the wrapping layer, and hot melt adhesive overflows from both ends; Problem and Effect Analysis: 1. Heat shrink tubing only generates shrinkage force during the moment of heating. Once cooled, the radial pressure it applies is fixed. Under long-term temperature cycling, material creep, and vibration, this pressure will gradually decay and cannot provide "active, continuous" compressive stress compensation like shape memory sleeves. 2. In mountainous and windy environments, it is extremely difficult to heat the heat shrink tubing evenly, which can easily lead to local overheating and burns or uneven shrinkage, leaving weak points in the seal; while the heat activation of the sheath of this invention is a gentle and uniform curing process, with relatively low requirements for heating uniformity. 3. Although heat shrink tubing is nominally weather resistant, the polyethylene outer shell will gradually become brittle and crack after long-term exposure to strong ultraviolet rays; the thermosetting composite material sheath of the present invention has an essential advantage in terms of UV resistance and high-temperature oxidation resistance. 4. Heat shrink tubing relies on the physical adhesion of hot melt adhesive, while this invention forms a more integrated "sandwich" structure by chemical bonding and physical interpenetration between the uncured outer adhesive and the sheath during the heat activation process, resulting in stronger peel resistance. Conclusion: The solution in Comparative Example 1 is simply a combination of two existing technologies (potting compound and heat shrink tubing), which cannot solve the problem of long-term dynamic sealing in mountainous environments, and its long-term reliability is lower than that of this solution.

[0032] Comparative Example 2: Omitting the dedicated interface-enhancing primer This comparative example omits the core primer step and relies solely on the adhesive strength of the sealant itself, which is a simplification that may be considered to reduce costs. Steps: Except for completely omitting "Step S2" (applying a special interface-enhancing primer), the remaining steps are exactly the same as in Example 1; after pretreatment, directly install the mold and pour the inner layer sealant; Problem and Effect Analysis: 1. Untreated polyolefin cable sheaths have low surface energy and are typical difficult-to-bond materials; although the sealant used in this invention contains an adhesion promoter, in the absence of a primer to pre-build a chemical bridge, its final bond strength (peel strength) test value is more than 60% lower than that of Example 1. 2. In high humidity or immersion environments, water molecules can more easily penetrate the interface between the sealant and the cable, leading to adhesion failure; the chemical bonding layer formed by the primer can effectively block the interface penetration of moisture; after 500 hours of double 85 aging test at 85℃ / 85%RH, the comparative sample showed visible bubbling and separation at the interface, while the example sample remained intact. 3. The interface is the weakest link in the sealing system; poor adhesion can directly lead to the seal detaching from the cable surface under shear stress or vibration generated by temperature cycling, creating a leakage path. Conclusion: Omitting the dedicated primer step weakens the interfacial bonding reliability of the entire sealing system, preventing high-performance sealing materials from performing effectively. This simplification will lead to premature joint failure under harsh environments.

[0033] Comparative Example 3: Replacing the composite sealing structure with a single layer of high-strength potting compound. This comparative example simulates another common approach: using a polyurethane or epoxy potting compound with higher hardness and better mechanical strength to cast a robust sealing shell in one go, in order to simplify the process. step: 1. The joint pretreatment is the same as step S1 in Example 1; 2. Install the same silicone mold; 3. Directly pour a high-hardness (Shore D>50), high-strength two-component polyurethane potting compound to fill the mold; 4. Heat to 60℃ to accelerate curing for 2 hours; 5. After demolding, a hard, sealed outer shell is obtained; there is no wrapping layer or outer sheath. Problem and Effect Analysis: 1. The thermal expansion coefficients of the hard potting compound and the cable are vastly different; under the severe day-night temperature difference cycle in the mountains, huge thermal stress will be generated inside; after dozens of temperature cycles, radial cracks appeared inside the seal or at the junction with the cable in the comparative sample; while the high elasticity silicone rubber of the inner layer of the present invention can absorb stress through deformation, and the outer sheath provides constraint but does not limit its elasticity. 2. Rigid shells are prone to fatigue fracture at stress concentration points (such as cable outlets) under continuous mechanical vibration; the composite structure of this invention has excellent vibration resistance and fatigue resistance characteristics. 3. Once solidified, the rigid shell cannot be opened. If there is a fault in the internal electrical connection, it can only be destroyed by force. Although the sealing system of this invention is also strong, it can be repaired by cutting open the tough sheath and elastomer in a relatively orderly manner with professional tools, making it more maintainable. 4. Due to the high hardness and large modulus of the material, the requirements for interface adhesion are higher, and even slight defects can easily lead to overall detachment; its construction error tolerance is lower than that of this invention. Conclusion: Simply using high-strength rigid potting compound is a static sealing approach and is not suitable for mountainous environments with dynamic thermal and mechanical stresses.

[0034] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0035] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A waterproof sealing process for mountain photovoltaic cable joints, characterized in that, The method includes the following steps: Step S1, Joint Area Pretreatment: Clean, roughen and preheat the surfaces of the electrically connected photovoltaic cable joints and adjacent cables; Step S2: Apply an interface-enhancing primer: Apply a layer of special primer to the treated surface and allow it to age; Step S3: Install the mold and pour the inner layer sealant: Install a temporary mold on the outside of the joint, pour two-component high elastic sealant into the mold, let it cure in situ to form an inner elastic seal, and then demold. Step S4, Winding the buffer reinforcement layer: On the outer surface of the inner elastic seal body, self-adhesive rubber tape and fiber-reinforced webbing are tightly wound in sequence to form a composite winding layer; Step S5, Apply adhesive and install the outer sheath: Apply adhesive to the surface of the composite winding layer, and then insert the uncured shape memory thermosetting composite material sheath; Step S6, Thermal Activation and Final Curing: The outer sheath is uniformly heated so that it undergoes thermal curing while activating the internal shape memory effect, thereby generating continuous radial compressive stress on the internal sealing structure. After cooling, a composite waterproof sealing structure is formed.

2. The waterproof sealing process for mountain photovoltaic cable joints according to claim 1, characterized in that, The preprocessing described in step S1 specifically includes: Use an organic solvent cleaner to thoroughly clean the cable joint and the surface of the cable outer sheath within a certain range on both sides; The cleaned area is then mechanically sanded to roughen the surface, and all sanding dust is then removed. Use hot air equipment to preheat the sanded area evenly to remove moisture and increase the surface temperature.

3. The waterproof sealing process for mountain photovoltaic cable joints according to claim 1, characterized in that, The special primer mentioned in step S2 is a silane-modified resin base coating, which includes silane-modified resin, adhesion promoter and nano thickener.

4. The waterproof sealing process for mountain photovoltaic cable joints according to claim 1, characterized in that, The two-component high-elasticity sealant described in step S3 is composed of two components, A and B, mixed in a certain proportion. Component A contains a polyorganosiloxane base polymer with reactive end groups, reinforcing fillers, and stabilizing agents, while component B contains a crosslinking agent and a catalyst.

5. The waterproof sealing process for mountain photovoltaic cable joints according to claim 4, characterized in that, The two-component high-elasticity sealant, after curing, forms a silicone rubber seal with permanent elasticity, which forms a chemical and physical bond with the cable surface after primer treatment.

6. The waterproof sealing process for mountain photovoltaic cable joints according to claim 1, characterized in that, The self-adhesive rubber tape mentioned in step S4 is a butyl rubber self-adhesive tape, and the fiber-reinforced webbing is a polyester fiber webbing impregnated with elastic resin; during winding, appropriate tension is applied to both materials respectively, and the specified overlap ratio is ensured.

7. The waterproof sealing process for mountain photovoltaic cable joints according to claim 1, characterized in that, The shape memory thermosetting composite material sheath mentioned in step S5 is an uncured prepreg tube, which is composed of a thermosetting resin matrix, radially oriented high modulus fibers, and thermo-induced shape memory polymer material.

8. The waterproof sealing process for mountain photovoltaic cable joints according to claim 1 or 7, characterized in that, The thermal activation process described in step S6 is as follows: the joint area covered by the sheath is uniformly heated to a specific temperature and maintained for a period of time. During this process, the resin matrix of the sheath undergoes a thermosetting reaction, and the internal shape memory material is activated, guiding the sheath to generate continuous radial shrinkage compressive stress.

9. The waterproof sealing process for mountain photovoltaic cable joints according to claim 8, characterized in that, The heating is performed using a ring-shaped hot air heating device or an infrared heating blanket. After heating is completed, the heating is allowed to cool naturally to room temperature, so that the sheath can be cured and the radial compressive stress can be locked.

10. The waterproof sealing process for mountain photovoltaic cable joints according to claim 1, characterized in that, After step S6 is completed, sealant should be used to seal the overlap between the two ends of the outer sheath and the cable outer sheath to form a waterproof skirt.

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