High-knot-toughness anti-escape net for offshore marine pile foundation fence, method for connecting high-knot-toughness anti-escape net with main netting and anti-escape system

Abstract

The invention provides a high-knot-toughness anti-escape net for an offshore marine pile foundation fence, a method for connecting the high-knot-toughness anti-escape net with a main netting and an anti-escape system. An anti-escape net unit adopts an HDPE / UHMWPE / POE multi-component composite system, multi-component composite monofilaments are prepared through a melt blending spinning method, and the core is that primary filaments are subjected to 10-14 times of online hot drafting in a non-aqueous liquid phase constant-temperature medium at 110-120 DEG C, so that the breaking strength of the monofilaments is larger than or equal to 9.0 cN / dtex, the knot strength is larger than or equal to 4.2 cN / dtex, the knot strength retention rate is larger than or equal to 47%, and the anti-escape net is formed. And the long-standing technical problem that high strength and high joint toughness are difficult to consider at the same time of the pile foundation fence is effectively solved. The invention further provides a connecting method of the escape-proof net unit and the main netting unit, rapid connection is achieved through the zipper system, and the connecting system of the main netting unit and the escape-proof net unit is formed. The composite board has the advantages of ultrahigh strength, high nodule toughness, excellent weather resistance and long service life, realizes quick disassembly and maintenance, greatly reduces the operation and maintenance cost and the safety risk, and provides reliable core material guarantee and a system solution for offshore marine maintenance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of offshore marine aquaculture pile foundation fence, and particularly relates to a preparation raw material of a high-knot-node toughness escape-proof net for offshore marine aquaculture pile foundation fence, a preparation method, a connection method of the high-knot-node toughness escape-proof net and a main net, and an escape-proof system composed of the high-knot-node toughness escape-proof net and the main net. BACKGROUND

[0002] With the increasing contradiction between the continuous growth of world population and the decline of offshore fishery resources, the development of offshore aquaculture space has become a strategic direction of global marine fishery. Offshore marine aquaculture pile foundation fence is one of the key equipment to realize this strategy, which is a large-scale engineering facility fixed in open sea area, and a controllable ecological system is constructed by enclosing water area through modular net system. The existing offshore marine aquaculture pile foundation fence adopts modular design, in which the modular main net unit as the main bearing structure of the system is fixed between adjacent pile foundations through high-performance net cable. These main net units and the bottom escape-proof net jointly constitute the basic aquaculture space enclosure system. As the core functional component installed at the bottom of the fence and directly contacting with the seabed, the escape-proof net is the "last line of defense" to block the escape of aquaculture organisms, and its comprehensive performance and connection reliability are directly related to the economic benefit and ecological safety of aquaculture, which can be called the "escape-proof cornerstone" of the entire fence system.

[0003] At present, the design of the main net unit-escape-proof net unit connection system is not perfect, and in the traditional system, the main net and the escape-proof net are mostly connected in a fixed way, which is difficult to realize the quick connection and separation between them, lacks the function of quick disassembly and assembly, and leads to difficult maintenance and high cost. When any component of the main net or the escape-proof net is damaged, a large amount of manpower and material resources are needed for repair and replacement, which seriously affects the continuity and economy of aquaculture operation. Therefore, it is urgent to develop a new type of connection system which can realize the quick and reliable connection between the modular main net and the escape-proof net, while ensuring the overall strength and durability of the system.

[0004] Especially worth noting is that the offshore environment is extremely harsh, with effective wave height usually reaching 3-8 meters, surface flow rate being 1.5-2.0 meters per second, strong bottom flow often accompanied by reciprocating flow or turbulence and other complex flow fields. Under such harsh environment, the escape-proof net is subjected to severe abrasion of seabed silt and reefs for a long time, and also faces multiple tests such as high salinity, strong ultraviolet radiation and marine organism attachment, which puts high requirements on the durability and connection reliability of the material. The existing fence escape-proof net and its connection technology with the main net have the following shortcomings under the harsh offshore working conditions:

[0005] First, the basic performance of the materials is insufficient: Currently, most offshore aquaculture escape-prevention nets are made of polyethylene (PE) or nylon 6 (PA6). Industry test data shows that the tensile strength of commercially available high-quality fishing-grade PE monofilaments is typically 5.0-6.0 cN / dtex, and the knot strength is 2.5-3.5 cN / dtex. Although PA6 monofilaments have slightly higher initial strength, the amide bonds in their molecular chains are easily hydrolyzed in offshore operating environments, resulting in poor corrosion resistance and rapid strength decay. When the escape-prevention net undergoes "pocket-like" deformation under the impact of strong currents, the stress on the net increases sharply, and the dynamic load easily exceeds the material's yield limit, causing the net to tear. In addition, the wear rate of the escape-prevention net at the contact point with the seabed is 3-5 times that of the surface part. Escape-prevention nets made of traditional PE netting will develop holes and significant strength degradation after 1-3 years of service under these conditions, resulting in high maintenance costs.

[0006] Secondly, the knot strength retention rate is low: knots are the weak points of the netting under complex stress, and the stress concentration coefficient at the knots can be 3-5 times that of the netting itself. For ultra-high strength fibers, such as pure ultra-high molecular weight polyethylene (UHMWPE) fibers, the knot strength retention rate (knot strength / breaking strength) of the netting is usually only 30%-40%, exhibiting a significant "high strength, low knot" phenomenon, and the related costs are high. The limitations of traditional spinning and cooling processes for ordinary fibers such as polyethylene monofilaments: using boiling water (95-100℃) for cooling results in a fixed and intense cooling intensity, leading to excessive internal stress in the nascent fibers, making the knots prone to cracking due to stress concentration. In offshore applications, it is common for the knots of escape-proof netting to break first, causing the mesh to expand and creating escape channels for farmed fish, while the netting itself remains intact. This chain reaction of damage seriously threatens aquaculture safety.

[0007] Third, the long-term durability of the materials needs improvement: long-term ultraviolet radiation causes photo-oxidative degradation of polyolefin materials. Traditional PE netting, under the harsh environment of offshore aquaculture, experiences a strength retention rate decrease of over 30% within 2-3 years. Simultaneously, marine organism attachment significantly increases the netting's fluid resistance, exacerbating wear and structural fatigue. While existing antifouling coatings can inhibit attachment in the short term, their components, such as organotin and copper ions, may pollute the aquaculture water. Regular underwater cleaning is costly and can easily damage the netting. Given the unique characteristics of escape-prevention nets operating in the harsh environment of offshore marine aquaculture, related technologies from other fields are not applicable to this area.

[0008] Fourth, the outdated connection method between the escape-prevention net and the main netting restricts the maintainability and economy of the system. Currently, the escape-prevention net and the main netting are generally permanently fixed by sewing or binding. This method has a fatal flaw: when either the main netting or the escape-prevention net is partially damaged due to wear or fatigue, it cannot be quickly replaced or repaired. During operation and maintenance, divers must be dispatched underwater for high-risk operations, consuming a large amount of manpower and financial resources for overall dismantling or in-situ repair. This not only restricts the operation window to harsh sea conditions and poses extremely high personnel safety risks, but also the long maintenance cycle will greatly affect the continuity of aquaculture production, causing huge economic losses. This "one-for-all" permanent fixed connection mode has become a key bottleneck restricting the modernization and cost reduction of offshore aquaculture equipment operation and maintenance. This invention belongs to the field of offshore marine aquaculture pile foundation fencing technology. Related technologies in other fields are not suitable for this technical field, and technical documents from other fields cannot be used as comparative technologies for this document.

[0009] In summary, there is an urgent need in this field for a systematic solution that can not only improve the strength, knot toughness, and durability of escape-prevention nets from the material source, but also innovate the connection method between the netting and the main body netting from the structural design perspective, achieving a fast, reliable, and reversible connection, thereby completely changing the traditional operation and maintenance mode. Currently, there is no mature technical solution in this field that can simultaneously overcome the two major challenges of the comprehensive performance of escape-prevention netting materials and the ease of connection between the escape-prevention netting and the main body netting. This has become one of the technical bottlenecks restricting the high-quality development of this field, and so far, those skilled in the art have no solution to this problem. Summary of the Invention

[0010] To address a series of problems with existing offshore aquaculture pile foundation fencing escape prevention nets, such as the difficulty in balancing material strength and knot toughness, insufficient long-term durability, and maintenance difficulties, high costs, and safety risks due to permanent fixed connection with the main netting, this invention provides a raw material and preparation method for a high-knot toughness escape prevention net for offshore aquaculture pile foundation fencing, as well as a method for connecting it to the main netting. The aim is to not only produce a high-performance escape prevention net that meets the requirements of extreme offshore working conditions through synergistic material innovation and system structure design, but also to fundamentally change its connection mode with the main netting, thereby solving at least one of the above-mentioned technical problems and ultimately achieving a balance between the safety, reliability, economical operation and maintenance, and ease of operation of the escape prevention net system.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] In a first aspect, the present invention provides a masterbatch for preparing an escape-proof net for offshore marine aquaculture pile foundation fencing. The preparation method is summarized as follows: the processed raw materials that have undergone deep drying and pretreatment are precisely mixed in the following weight parts and then melt-blended and underwater pelletized: 70-80 parts HDPE, 15-25 parts UHMWPE, 3-10 parts POE, 0.8-1.2 parts compatibilizer and 0.4-0.6 parts composite antioxidant.

[0013] Preferably, the melt index of HDPE is 1.0 g / 10 min, the viscosity-average molecular weight of UHMWPE is 3.5 million, the compatibilizer is selected from PE-g-MAH, and the composite antioxidant is selected from antioxidant 1010 and 168 compounded in a 1:1 mass ratio.

[0014] The method for deep drying and pretreatment of raw materials is as follows: All raw materials are dried at 105℃±2℃ and -0.095MPa vacuum for 28 hours to ensure that the moisture content of the material is consistently below 120ppm. After drying, the material is immediately transferred to a sealed container filled with dry nitrogen for later use, and moisture reabsorption is strictly prevented. This step is crucial to avoid hydrolytic degradation and microporous defects caused by moisture during melt blending.

[0015] The original precise mixing method was as follows: all raw materials were mixed according to the above weight proportions and then fed into a high-speed mixer. The mixer was operated strictly according to a stepped program of mixing at low speed (350 rpm) for 5 minutes and then at high speed (1050 rpm) for 15 minutes. Through high-intensity shearing action, the UHMWPE powder and POE elastomer particles, which were originally very prone to agglomeration, were uniformly dispersed in the HDPE matrix at the submicron scale, forming a highly uniform premix, which provides a structural basis for subsequent spinning.

[0016] The conditions for melt blending and underwater pelletizing are as follows: The premixed material is added to a co-rotating twin-screw extruder. To achieve optimal plasticization and dispersion, the temperatures of each section are precisely set as follows: Zone 1: 165℃ (solid conveying section); Zone 2: 185℃ (initial melt section); Zone 3: 225℃ (intense mixing section, high shear); Zone 4: 245℃ (homogenization section); Zone 5: 255℃ (extrusion section); the screw speed is set to 210 rpm; after the melt is extruded through the multi-hole die, it is immediately subjected to rapid cooling in a 25℃ constant temperature water bath to effectively "freeze" the formed excellent microstructure and prevent phase growth. Subsequently, it is pelletized into cylindrical composite masterbatches using a pelletizer.

[0017] In a second aspect, this invention provides a composite monofilament for preparing an escape-proof net for offshore aquaculture pile foundation fencing. The preparation method includes the following steps: the composite masterbatch prepared in the first aspect is fed into a single-screw spinning machine, and the spinning temperature adopts a gradient heating strategy: zone 1 170℃ (feeding section), zone 2 190℃ (compression section), zone 3 220℃ (metering section), zone 4 235℃ (filtration section, using a 250-mesh filter), and zone 5 240℃ (spinneret section); the melt is transported to the spinneret (φ1.0mm) by a precision metering pump to extrude nascent filaments, which are immediately placed in a constant temperature water bath at 25℃±0.5℃ for rapid cooling and solidification; subsequently, the solidified filaments are introduced into a non-aqueous liquid phase constant temperature medium at 110-120℃ for 10-14 times online thermal stretching to obtain the composite monofilament.

[0018] Preferably, the non-aqueous liquid-phase isothermal medium is dimethyl silicone oil, synthetic hydrocarbon hot oil, or mineral oil. This non-aqueous medium environment is key to the present invention, as it provides a mild and uniform thermal field, allowing the UHMWPE molecular chains to fully extend and orient, while the POE elastomer phase is activated at the optimal temperature, achieving a synergistic effect of toughening and strengthening, which cannot be achieved by the drastic cooling of traditional boiling water (100°C).

[0019] To address the key process parameters of this invention (10-14 times online hot drawing in a non-aqueous liquid-phase isothermal medium at 110-120℃), the inventors conducted numerous arduous spinning experiments and demonstrations. Under the same conditions, if the spinning temperature is below 110℃ or the drawing ratio is less than 10 times, the breaking strength of the produced composite monofilament is below 8.5 cN / dtex; if the spinning temperature is above 120℃ or the drawing ratio is greater than 14 times, filament breakage occurs during composite monofilament production, failing to meet industrial production requirements. Experimental results show that exceeding the range of key process parameters set in this invention leads to adverse technical effects. These key process parameters are not obvious, and the inventors conducted countless experiments, expending considerable effort, and achieving unexpected technical results. The winding speed was set to 450 m / min. Finally, a multi-element composite monofilament with a nominal diameter of 0.15 mm ± 0.01 mm was obtained.

[0020] One of the core innovations of this invention lies in the creative selection of the thermal drawing process medium and its resulting synergistic effect. Traditional boiling water (95-100℃) cooling drawing processes have two major limitations: first, the temperature is below the full extension temperature of the UHMWPE molecular chains, preventing the full release of its reinforcing potential; second, the intense vaporization and cooling of water generates significant internal stress and micro-defects within the fiber, becoming crack sources when the nodules are under stress. This invention uses a non-aqueous liquid-phase isothermal medium (such as dimethyl silicone oil) at 110-120℃. The technical principle is that this medium provides a mild and uniform thermal environment above the boiling point of water, allowing the ultra-long UHMWPE molecular chains sufficient thermal motion and relaxation time for full untangling, extension, and high orientation, thereby maximizing its reinforcing effect and achieving near-pure UHMWPE fiber high tensile strength. Simultaneously, this temperature range is also precisely the "activation window" for the POE toughening phase, enabling it to more effectively form uniformly distributed elastic microregions within the fiber. This stable island structure, formed by the "rigid UHMWPE skeleton" and "elastic POE microregions" under optimal processing conditions, can effectively passivate crack tips and disperse stress concentration by consuming a large amount of energy through the yielding, crimping, and shear banding of the POE phase when deformation occurs at the nodule, thus achieving ultra-high strength while significantly improving nodule toughness. Test results show that the fracture strength of the multi-element composite monofilament prepared in this invention is ≥9.0 cN / dtex, and the nodule strength is ≥4.2 cN / dtex, far exceeding that of monofilaments in existing technologies.

[0021] In a third aspect, the present invention provides an escape-proof netting unit for offshore aquaculture pile foundation fencing, comprising the multi-component composite monofilaments described in the second aspect, which are twisted into netting, woven into netting sheets, heat-set, and assembled, as detailed below:

[0022] (1) The twisting of the network cable shall adopt at least one of the following standardized methods:

[0023] Option A: Using 20 of the aforementioned composite monofilaments as one strand, perform initial twisting in the Z direction, and then perform S-direction retwisting of the three initial twisted strands to obtain a general-purpose high-strength network cable;

[0024] Option B: Using 16 of the aforementioned composite monofilaments as one strand, the first strand is twisted in the Z direction, and the three strands of the first twisted strand are then twisted again in the S direction to obtain a highly flexible and fatigue-resistant network cable;

[0025] Option C: Using 36 of the aforementioned composite monofilaments as one strand, perform initial twisting in the Z direction, and then perform S-direction retwisting of the three initial twisted strands to obtain an extra-heavy-duty network cable.

[0026] (2) The weaving and heat setting methods for the netting are as follows: any twisted netting yarn from schemes A to C is loaded onto an intelligent knotless warp knitting machine. The mesh size is then set according to the body shape parameters of the target aquaculture species. During the weaving process, a closed-loop control system composed of integrated tension sensors monitors and maintains the specific tension of the netting yarn at a constant 25N±1N~27±1N in real time. After weaving, the netting is immediately sent to a heat setting unit for overall heat setting treatment at 120℃±3℃ for 30 minutes. This heat setting treatment effectively eliminates internal stress and significantly improves the dimensional stability of the netting under seawater immersion and dynamic wave impact. Tests show that its long-term shrinkage rate can be controlled within 1%, thus obtaining a general-purpose high-strength, high-knot toughness escape-proof netting.

[0027] (3) The method of assembling the netting into an anti-escape netting unit is as follows: cut the anti-escape netting and splice it into a netting unit whose length matches the lower mesh size of the modular main netting unit. Integrate the netting unit with high-performance netting of different fiber materials for edge reinforcement, and set connecting ears on the bottom lower mesh for connection with the anchoring structure of the modular main netting unit to obtain the anti-escape netting unit.

[0028] Preferably, one LCP fiber mesh, one PBO fiber mesh, and one polyester-propylene fiber hybrid mesh are installed on the upper mesh, 25-35cm below the upper mesh, and the lower mesh of the netting unit, respectively, and a hybrid polyolefin mesh is installed in other areas. The breaking strength of all meshes is ≥51 tons.

[0029] In a fourth aspect, the present invention provides a method for connecting an escape-proof net to the main mesh of an offshore aquaculture pile foundation fence, comprising the following steps:

[0030] S1: Provide multiple anti-escape net units as described in the third aspect;

[0031] S2: Provides multiple modular main body mesh units, each equipped with a high-performance mesh.

[0032] S3: The high-performance mesh of the escape prevention net unit is quickly connected to the corresponding mesh on the main net unit through a zipper system, thereby forming a main net unit-escape prevention net unit connection system.

[0033] Preferably, before step S3, the method further includes: setting a wear-resistant buffer layer on the side of the net that contacts the seabed of the escape-proof net unit; preferably, equipping it with a 12mm thick nitrile rubber pad, which has high wear resistance and elasticity and can effectively buffer the direct friction between the escape-proof net and the seabed mud, sand, reefs, etc., which is an innovative measure to extend the life of the net.

[0034] Following step S3, the method further includes connecting the connecting lugs on the bottom lower section of the escape-prevention net unit to the anchoring structure buried on the seabed via a high-strength pull chain. Specifically, the connecting lugs on the bottom lower section of the escape-prevention net unit are moderately dragged outwards from the fence and connected to pre-embedded basalt fiber composite reinforced concrete anchor blocks via a 57t breaking strength carbon fiber pull chain. This bottom anchoring system of "anchor block-carbon fiber chain-escape-prevention net" constitutes a flexible anchoring network deeply buried on the seabed with high pull-out resistance, greatly improving the overall stability of the entire offshore marine aquaculture pile-based escape-prevention net system under wind and waves.

[0035] Preferably, the zipper system is a high-strength waterproof zipper made of an alloy material resistant to seawater corrosion (such as copper-nickel alloy material), and its breaking strength is not lower than the breaking strength of the main mesh unit.

[0036] In a fifth aspect, the present invention provides an escape prevention system for offshore marine aquaculture pile foundation fencing, comprising: at least one escape prevention net unit as described in the third aspect; at least one modular main net unit; and a main net unit-escape prevention net unit connection system constructed using the connection method described in the fourth aspect.

[0037] The escape prevention system is installed in a modular manner between adjacent piles of the pile foundation fence. The adjacent escape prevention net units are sewn together with HMPE stitching rope with a diameter of 4.2mm and a stitch spacing of 120mm using a "double-line overlock" stitching method. The number of stitches per centimeter at the sewn joint is consistently 3.5. A 0.5mm thick HMPE woven fabric protective cover is added to the connection part for sewing and connecting, forming a continuous and integrated escape prevention barrier.

[0038] The beneficial protections and effects of this invention are as follows:

[0039] Compared with the prior art, the technical solution provided by this invention brings about significant technological progress in multiple aspects and across multiple levels, and achieves remarkable technical effects, specifically reflected in the following aspects:

[0040] 1. Breakthrough progress in material properties, collaboratively solving the industry challenge of "high strength and low structural strength".

[0041] This invention utilizes a specific ratio of HDPE / UHMWPE / POE raw materials, combined with a core process of 10-14 times hot stretching in a non-aqueous liquid phase isothermal medium at 110-120℃, resulting in a positive synergistic effect. This specific combination optimizes the "rigid-elastic" island microstructure of the fiber, enabling the POE toughening phase to be uniformly distributed and fully activated at the submicron scale. While ensuring the high orientation and crystallinity of the UHMWPE reinforcing phase, it significantly improves the material's toughness. Scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA) results confirm this unique structure. The prepared multi-component composite monofilament achieved unexpected technical effects: a breaking strength ≥9.0 cN / dtex, approaching the level of pure UHMWPE melt-spun monofilament, while a knot strength ≥4.2 cN / dtex, reaching more than 1.5 times that of traditional PE monofilament. The knot strength retention rate was significantly increased from 30-40% in traditional UHMWPE multifilament fibers to over 47%. It is particularly noteworthy that, with the raw material formulation completely identical, simply replacing the hot drawing medium from "boiling water" to "115℃ silicone oil" resulted in a 24.4% increase in knot strength and an increase in knot strength retention from 46.2% to 49.5%. This result verifies the uniqueness and effectiveness of the core process of this invention. Furthermore, the superior properties of the multi-component composite monofilament developed in this invention can be utilized to extend its application to netting in other fields.

[0042] 2. The overall performance of the product has been significantly improved, and its safety assurance capabilities have been greatly enhanced.

[0043] Thanks to the innovation in the material system, the core mechanical properties of this invention's escape-prevention net surpass those of existing similar products by 30%-100%. The heavy-duty net cable in the embodiment has an average breaking strength of 1710 N and an average knot strength of 964 N, capable of withstanding higher levels of extreme sea conditions such as wave heights of 5m and current velocities of 1.8m / s. System durability testing shows that after 3000 hours of accelerated UV aging, the net's breaking strength retention rate remains above 85%, far superior to the 60% of ordinary PE netting; the high-flexibility, fatigue-resistant net cable retains ≥85% of its strength after 10,000 fatigue cycles. Combined with excellent wear resistance and anti-bioadhesion properties, the expected fault-free service life of this invention's escape-prevention net is extended from the conventional 3-5 years to over 7 years, and the total life-cycle cost can be reduced by more than 40%, resulting in significant economic benefits.

[0044] 3. Innovative connectivity methods trigger fundamental changes in operation and maintenance models.

[0045] This invention presents a rapid connection method based on a zipper system, completely revolutionizing the outdated fixed connection between traditional escape-prevention nets and the main netting. This method enables rapid connection and separation of escape-prevention net units, allowing for quick replacement on a surface platform in case of partial damage. It completely avoids the high-risk, high-cost underwater sewing work by divers, significantly improving operational efficiency and safety, and resolving a long-standing operational bottleneck that has constrained the development of offshore aquaculture equipment. This innovation not only reduces maintenance costs but also greatly improves the continuity and reliability of aquaculture production.

[0046] 4. System integration enables multi-functional synergy and efficiency enhancement.

[0047] This invention optimizes the netting system as an organic whole through integrated design of materials, structure, and function. The mesh size (8mm-55mm) is precisely set according to the body size of the target aquaculture species and the hydrodynamic characteristics of the enclosure bottom, achieving an optimal balance between escape prevention effectiveness and water exchange efficiency. Tank tests confirm that the netting of this invention exhibits excellent hydrodynamic performance and good permeability. When integrated with high-performance netting such as PBO and LCP and a quick-connect system, it forms a multi-layered synergistic flow reduction and wave resistance effect, creating a more stable aquatic environment for the aquaculture area.

[0048] 5. Overall aquaculture benefits have been significantly improved.

[0049] Practical applications show that the complete solution constructed by this invention can significantly reduce stress response in farmed fish, increase growth rate by more than 2.3%, and improve fish quality, achieving a leap from passive escape prevention to proactive improvement of aquaculture efficiency. In trials in sea areas such as Zhejiang, the offshore marine aquaculture piling fence system of this invention maintained structural integrity under extreme weather conditions such as typhoons, increased the growth rate of farmed fish by more than 2.3%, and significantly improved the quality of farmed fish.

[0050] 6. It has strong industrialization feasibility and aligns with the concept of green development.

[0051] The raw materials used in this invention are all mass-produced industrial products with a stable supply chain. The core preparation process is based on existing mature equipment and can be implemented with only adaptive modifications to the hot stretching medium tank, making it a low-barrier-to-entry technology upgrade, ideal for traditional fishing net manufacturers to upgrade and transform. The three standardized netting solutions provided can be precisely adapted to different marine environments, offering high application flexibility. In addition, the netting material is recyclable and reusable, and its smooth, dense surface reduces the need for antifouling coatings, lowering the risk of environmental pollution at the source and meeting the requirements of circular economy and ecological aquaculture.

[0052] In summary, this invention, through material innovation, technological breakthroughs, and system integration, has achieved a leap from "meeting basic functions" to "providing comprehensive solutions" in anti-escape net technology. It not only solves the key material bottleneck in offshore aquaculture but also provides a successful paradigm for the development of traditional industries towards high technology and high added value, resulting in significant comprehensive benefits. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the connection between the escape prevention net unit and the main netting unit in specific embodiment 2 of the present invention;

[0054] Figure 2 This is a schematic diagram of the anti-escape net unit in specific embodiment 2 of the present invention;

[0055] Figure 3 This is a schematic diagram of the main mesh unit in specific embodiment 2 of the present invention.

[0056] The components include: 1. Main mesh unit; 2. First connection and fixing position between the escape-proof net unit and the main mesh unit; 3. Second connection and fixing position between the escape-proof net unit and the main mesh unit; 4. Nitrile rubber pad mounted on the escape-proof net unit; 5. Carbon fiber pull chain; 6. Basalt fiber composite reinforced concrete anchor block; 7. Connecting lug; 11. Left side bar of the main mesh unit; 12. First mesh bar mounted on the main mesh unit for connecting and fixing with the escape-proof net unit; 13. Mesh bar mounted on the main mesh unit for connecting with the escape-proof net unit. 14. The lower mesh of the main mesh unit; 15. The upper mesh of the main mesh unit; 16. The right side mesh of the main mesh unit; 21. The upper mesh of the escape prevention net unit; 22. The first mesh installed on the escape prevention net unit for connecting and fixing with the main mesh unit; 23. The second mesh installed on the escape prevention net unit for connecting and fixing with the main mesh unit; 24. The left side mesh of the escape prevention net unit; 25. The connecting lug on the lower mesh of the escape prevention net unit; 26. The right side mesh of the escape prevention net unit; 27. The lower mesh of the escape prevention net unit. Detailed Implementation

[0057] The present invention will be further described below with reference to the accompanying drawings. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in great detail and without limitation below with reference to the accompanying drawings and preferred embodiments. It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods; the reagents and materials described, unless otherwise specified, are all commercially available. Those skilled in the art will understand that various changes, modifications, and substitutions made to these embodiments without departing from the spirit and substance of the present invention fall within the protection scope of the present invention.

[0058] Example 1: Preparation and performance characterization of multi-component composite monofilaments

[0059] This embodiment details the preparation process of the core material—multi-component composite monofilament—and demonstrates its performance data, focusing on verifying the technical effects brought about by the synergistic effect of the non-aqueous spinning medium and the multi-component composite system.

[0060] 1. Raw materials and equipment

[0061] Raw materials: HDPE (grade 5000S, Sinopec Yangzi Petrochemical Co., Ltd., melt index 1.0g / 10min (190℃, 2.16kg)), UHMWPE powder (grade LL-1040, Shanghai Lianle Chemical Technology Co., Ltd., viscosity-average molecular weight 3.5 million), POE (grade 8540, Dow Chemical), compatibilizer PE-g-MAH (grade 4351, Clariant), antioxidants 1010 and 168 (BASF, compounded in a 1:1 mass ratio).

[0062] Equipment: Vacuum drying oven, high-speed mixer (speed range 300-1200rpm), co-rotating parallel twin-screw extruder (screw diameter φ75mm, length-to-diameter ratio 44:1), single-screw spinning machine (length-to-diameter ratio 33:1), non-aqueous liquid phase constant temperature medium bath (temperature control accuracy ±0.5℃), drawing machine, precision winding machine.

[0063] 2. Preparation process

[0064] Step 1: Deep Drying and Pretreatment of Raw Materials. All raw materials and additives are dried at 105℃±2℃ and -0.095MPa vacuum for 28 hours to ensure that the moisture content of the materials is consistently below 120ppm. After drying, the materials are immediately transferred to a sealed container filled with dry nitrogen for later use, strictly preventing moisture regain. This step is crucial to avoid hydrolytic degradation and microporous defects caused by moisture during melt blending.

[0065] Step Two: Precise Ingredient Formulation and Efficient Mixing. Weigh the following ingredients precisely according to the following weight ratio: HDPE: 75.7 kg, UHMWPE: 20 kg, POE: 3 kg, PE-g-MAH: 0.8 kg, Composite Antioxidant (1010 / 168=1:1): 0.5 kg. This weight ratio is a standard scheme, emphasizing a balanced overall performance. Add all materials to a high-speed mixer and strictly follow a stepped mixing procedure: "low speed 350 rpm mixing for 5 min + high speed 1050 rpm mixing for 15 min". Through high-intensity shearing action, the originally easily agglomerated UHMWPE powder and POE elastomer particles are uniformly dispersed at a submicron scale within the HDPE matrix, forming a highly uniform premix that provides the structural basis for subsequent spinning.

[0066] Step 3: Melt Blending and Underwater Pelletizing. The premixed material is added to a co-rotating twin-screw extruder. To achieve optimal plasticization and dispersion, the temperatures of each section are precisely set as follows: Zone 1 165℃ (solid conveying section), Zone 2 185℃ (initial melt section), Zone 3 225℃ (intense mixing section, high shear), Zone 4 245℃ (homogenization section), and Zone 5 255℃ (extrusion section). The screw speed is set to 210 rpm. After extrusion through the multi-hole die, the melt is immediately subjected to rapid cooling in a 25℃ constant-temperature water bath to effectively "freeze" the formed excellent microstructure and prevent phase growth. Subsequently, it is pelletized into cylindrical composite masterbatches of φ3×3mm, named "UH / H / OE-1" composite masterbatch. This composite masterbatch has uniform particles, a smooth surface, and is free of bubbles, meeting the requirements of precision spinning.

[0067] Step Four: Precision Spinning and Online Hot Drawing (Core Innovative Step). The "UH / H / OE-1" composite masterbatch is fed into a single-screw spinning mill. A gradient temperature increase strategy is adopted for spinning: Zone 1 170℃ (feed section), Zone 2 190℃ (compression section), Zone 3 220℃ (metering section), Zone 4 235℃ (filtration section, using a 250-mesh filter), and Zone 5 240℃ (spinneret section). The spinneret orifice diameter is φ1.0mm. The melt is stably conveyed by a precision metering pump (accuracy ±0.5%), extruding nascent filaments. The nascent filaments are immediately subjected to rapid cooling and solidification in a constant-temperature water bath at 25℃±0.5℃. This step aims to form a regular core-sheath structure prototype. Subsequently, the solidified filaments are introduced into a constant-temperature medium bath filled with dimethyl silicone oil (kinematic viscosity 30 cSt to 40 cSt) and subjected to 12 times synchronous bidirectional hot drawing at 115℃±0.5℃. This non-aqueous medium environment is key to the invention. It provides a mild and uniform thermal field, allowing the UHMWPE molecular chains to fully extend and orient, while the POE elastomer phase is activated at the optimal temperature, achieving a synergistic effect of toughening and strengthening, which cannot be achieved by the drastic cooling of traditional boiling water (100°C).

[0068] To address the key process parameters of this invention (10-14 times online thermal stretching in a non-aqueous liquid-phase isothermal medium at 110-120℃), the inventors conducted extensive and arduous spinning experiments. Under the same conditions, if the spinning temperature is below 110℃ or the stretching ratio is less than 10 times, the breaking strength of the produced composite monofilament is below 8.5 cN / dtex; if the spinning temperature is above 120℃ or the stretching ratio is greater than 14 times, filament breakage occurs during composite monofilament production, failing to meet industrial production requirements. Experimental results show that exceeding the range of the key process parameters set in this invention leads to adverse technical effects, and these key process parameters are not obvious. The winding speed was set to 450 m / min. Finally, a multi-element composite monofilament with a nominal diameter of 0.15 mm ± 0.01 mm was obtained.

[0069] 3. Performance Characterization and Results

[0070] The obtained high-performance composite monofilaments underwent comprehensive mechanical, thermal, and durability tests. All tests were conducted according to relevant standards. The test results, along with those of Comparative Example 1 (commercially available high-quality pure fishery polyethylene (PE) monofilaments) and Comparative Example 2 (comparative monofilaments subjected to hot drawing using boiling water at 100°C, with the same raw material formulation as this example), are listed in Table 1 below:

[0071] Table 1. Overall Performance Comparison of Example 1 with Comparative Examples 1 and 2

[0072]

[0073] Based on the comparative data above, it is evident that the high-performance composite monofilament prepared in Example 1 of this invention significantly surpasses the comparative example in key indicators such as nodule strength retention rate, fatigue resistance, and strength retention rate after UV aging. Particularly noteworthy is that, compared to Comparative Example 2 (boiling water medium), this invention maintains ultra-high tensile strength (9.05 cN / dtex) while increasing nodule strength by 24.4%, and raising the nodule strength retention rate from 46.2% to 49.5%, demonstrating the non-obvious nature of the core process of this invention. Simultaneously, fatigue resistance and UV aging resistance are significantly improved. This fully demonstrates that the specific combination of material formulation and process parameters employed in this invention brings about a synergistic effect, effectively solving the "high strength, low knot" problem commonly found in high-strength fibers in this field. It unexpectedly solves the global challenge of achieving both high strength and high nodule toughness simultaneously, achieving unexpected technical results and laying an irreplaceable material foundation for creating high-performance, high-nodule toughness escape-proof nets. The technical achievement of this invention has significant and unexpected improvements in key indicators such as nodule strength retention rate, fatigue resistance, and strength retention rate after ultraviolet aging. The overall effect of the technical solution of this invention is very significant.

[0074] Example 2: Manufacturing and Application Verification of a General-Purpose High-Strength Escape Prevention Net Unit

[0075] This embodiment demonstrates how to transform the high-performance composite monofilament prepared in Example 1 into a practically usable high-strength escape-proof net unit, and verifies its application.

[0076] 1. Network cable preparation

[0077] The high-performance composite monofilament prepared in Example 1 was used to prepare a three-strand network cable using the following parameters to obtain a general-purpose high-strength network cable.

[0078] (1) Initial twisting: 20 monofilaments are bundled into one strand and twisted in a "Z" direction, with the twist strictly controlled at 30T / m;

[0079] (2) Retwisting: The three initial twisted yarns are combined and twisted in an "S" direction, with the twist strictly controlled at 40T / m;

[0080] (3) The nominal diameter of the finished general-purpose high-strength network cable is 2.48 mm (±0.03 mm).

[0081] 2. Network cable performance test

[0082] Ten randomly selected samples of general-purpose high-strength network cable were tested on a universal testing machine. The measured average breaking strength was 1290 N; the average nodal strength was 676 N; and the elongation at break was 20.8%, with a data dispersion coefficient of less than 2.5%. The above data indicate that the general-purpose high-strength network cable has a uniform structure, stable overall performance, and meets the design requirements.

[0083] 3. Mesh weaving

[0084] First, the netting prepared in (1) was loaded onto an intelligent knotless warp knitting machine; then, based on the body shape parameters of the target aquaculture species (adult large yellow croaker, average body length 35cm), the mesh size was optimized and set to 40mm. During the weaving process, a closed-loop control system composed of integrated tension sensors was used to monitor and maintain the specific tension of the netting at 25N±1N in real time, ensuring that each mesh was regular in shape and the knots were tight and consistent. The above-mentioned specific tension achieved unexpected technical effects.

[0085] After weaving, the netting is immediately sent to a heat setting machine for 30 minutes of overall heat setting at 120℃±3℃. This treatment effectively eliminates internal stress and significantly improves the dimensional stability of the netting under seawater immersion and dynamic wave impact. Tests show that its long-term shrinkage rate can be controlled within 1%, thus obtaining a general-purpose high-strength, high-knot toughness escape-proof netting.

[0086] 4. Mesh performance testing

[0087] Fifteen samples containing complete meshes were randomly cut from the aforementioned finished general-purpose high-strength, high-knot toughness escape-proof mesh for testing:

[0088] (1) Mesh breaking strength test: The mesh breaking strength test was carried out on a universal testing machine. The results showed that the average breaking strength of the 15 samples was 850 N, the minimum value was 816 N, and the data dispersion coefficient was less than 3%, indicating that the general-purpose high-strength high-knot toughness anti-escape mesh has excellent weaving technology and the quality of the general-purpose high-strength high-knot toughness anti-escape mesh is uniform and stable.

[0089] (2) Hydrodynamic performance test: In the water tank, a water flow of 0.3 m / s-1.5 m / s was applied to the 1m×1m general-purpose high-strength high-nodular toughness escape-proof net sample. The test results showed that the general-purpose high-strength high-nodular toughness escape-proof net had small deformation and high water flow rate, which met the design requirements and proved that the general-purpose high-strength high-nodular toughness escape-proof net has excellent water permeability.

[0090] 5. Assembly of anti-escape net units

[0091] Following a modular design, the escape-proof netting panels are cut and assembled into escape-proof netting units with a width of 2.6m and a length of 25m (this length matches the lower frame dimensions of an exemplary 25m long modular main netting unit). See also Figure 2 The net unit is integrated with high-performance nets made of different fiber materials: one LCP fiber net, one PBO fiber net, and one polyester-propylene fiber hybrid net are installed at position 22 (30cm below the upper net) and position 27 of the escape-proof net unit 21, respectively; and mixed polyolefin nets are installed in other areas. All nets have a breaking strength ≥ 51 tons. HMPE stitching cord with a diameter of 4.2mm is used, with double-stitched seams at a stitch spacing of 120mm. The number of stitches per centimeter at the seam is consistently 3.5, and a 0.5mm thick HMPE woven fabric protective sleeve is added to the connection points. Connecting lugs 25 are installed at 1.5m intervals on the lower net at the bottom of the escape-proof net unit for connection to the carbon fiber traction chain 5 of the offshore marine aquaculture pile foundation fence escape-proof net anchoring structure.

[0092] 6. Application Validation

[0093] Combination Figure 1 The escape-prevention net unit was connected to the main netting unit via a zipper system at the first connection fixing point 2 and the second connection fixing point 3, and deployed in an offshore area of ​​the East China Sea. After deployment, the area experienced a typhoon, with the maximum wave height in the surrounding waters reaching 4.5m and the maximum current speed reaching 1.3m / s. Subsequent underwater inspection by divers confirmed that the escape-prevention net structure was intact, with no broken netting, slipped knots, or obvious permanent deformation. The connection between the escape-prevention net and the main netting of the enclosure was reliable, effectively ensuring that no farmed fish escaped from the enclosed aquaculture area, demonstrating the good suitability of the escape-prevention system for fishing.

[0094] Example 3: Preparation and Performance Verification of Extra Heavy-Duty Escape Prevention Net

[0095] This embodiment demonstrates the fabrication and verification of an extra-heavy-duty escape-proof net, targeting high-energy environments with harsh wave and current conditions and numerous seabed reefs.

[0096] 1. Material and process upgrades

[0097] (i) Composite monofilament formulation optimization: The same process flow and 115°C silicone oil medium as in Example 1 were used, but the formulation was optimized by increasing the POE content to 4.0% and adjusting the HDPE content accordingly to 74.7% (i.e., the optimized composite monofilament formulation is: HDPE 74.7%, UHMWPE 20.0%, POE 4.0%, PE-g-MAH 0.8%, antioxidant 0.5%). This fine-tuning aims to further enhance the toughness reserve and fatigue resistance of the material under repeated impact loading without significantly sacrificing strength, by utilizing the POE phase.

[0098] (ii) Net cable twisting: The net cable is processed using the parameters of scheme C (extra heavy load type) in claim 3. 36 monofilaments with fine-tuned formula are used as one strand. The initial twist ("Z" direction) is set to 25 T / m to retain the strength of the monofilament to the maximum extent. Then, the twist of the three strands ("S" direction) is increased to 50 T / m to ensure that the strand structure is compact, the net cable is wear-resistant, and the overall stress is uniform. This results in an extra heavy load type net cable.

[0099] (iii) Surface coating treatment of the network cable: The surface of the above-mentioned heavy-duty network cable is coated with a polyurethane-ceramic nanocomposite wear-resistant coating and a fouling and biofouling-resistant coating of about 8μm thickness to cope with the sharp scratches of reefs and the attachment of marine fouling organisms (such as mussels, oysters, moss, geckos, etc.).

[0100] (iv) Performance test: The above-mentioned heavy-duty network cable was subjected to a comprehensive performance test. Its measured diameter was 3.98 mm, the average breaking strength was 1710 N, and the average knot strength was 964 N.

[0101] 2. Escape prevention net unit manufacturing

[0102] The following scheme parameters are used to prepare a three-strand network cable to obtain an extra-heavy-duty network cable:

[0103] (1) Initial twisting: 36 monofilaments are bundled into one strand and twisted in a "Z" direction, with the twist strictly controlled at 30T / m;

[0104] (2) Retwisting: Combine the three initial twisted yarns and twist them together in an "S" direction. The twist degree is strictly controlled at 40T / m.

[0105] The heavy-duty netting fabric prepared according to the above method was loaded onto an intelligent knotless warp knitting machine. Based on the body size parameters of the target aquaculture species (adult large yellow croaker, average body length 39cm), the mesh size was optimized to 42mm. Following the same netting weaving process and heat treatment as in Example 2, the tension of the heavy-duty netting fabric was kept constant at 27N±1N to complete the netting weaving and heat treatment, thus obtaining a heavy-duty, high-knot toughness escape-proof netting. It was then assembled into an escape-proof netting unit according to the same process as in Example 2. The structure of the escape-proof netting unit is as follows...Figure 2 As shown, 21 is the superstructure, 22 and 23 are connecting mesh structures, 24 and 26 are edge structures, 27 is the substructure, and 25 is the connecting lug.

[0106] 3. Performance Verification

[0107] (i) Water flow impact test: A 1m × 1m sample of the heavy-duty, high-nodularity, tough escape-proof mesh was tested in a water tank. It was subjected to continuous impact for 7 hours at a constant flow velocity of 1.0 m / s. After the test, observation revealed that the mesh remained intact, the mesh fibers were not broken, and the mesh shape remained stable, with no plastic deformation observed. The results indicate that this heavy-duty, high-nodularity, tough escape-proof mesh possesses excellent structural robustness and resistance to water flow impact.

[0108] (ii) Abrasion test: The above-mentioned heavy-duty mesh cable was subjected to accelerated abrasion test using an abrasion test device. After 1200 friction tests, its strength retention rate was as high as 87.3%, and the mesh cable met the abrasion resistance requirements of the seabed with multiple reefs.

[0109] (iii) The test results show that the escape prevention net is applicable in harsh environments and the technical effect of the present invention is obvious.

[0110] Example 4: Integrated Construction and Comprehensive Effectiveness of Anti-Escape Net System in Offshore Pile Foundation Fence

[0111] This embodiment illustrates the integrated construction method and comprehensive effectiveness of the anti-escape net system in offshore pile foundation fences, and comprehensively evaluates its technical effects through monitoring the entire system.

[0112] 1. Pre-fabrication of the connection system between the main mesh unit and the escape prevention net unit

[0113] In suitable locations such as onshore or offshore platforms, modular main mesh units (25m × 8m in size, structure as follows) will be installed. Figure 3 As shown, 11 is the left side line, 16 is the right side line, 14 is the lower line, 15 is the upper line, and 12 and 13 are connecting lines) and the corresponding escape prevention net unit (size: 25m × 2.6m, structure as shown) Figure 2 The key step in pre-connecting the modular main mesh unit (as shown) is to quickly and accurately connect the PBO fiber mesh and LCP fiber mesh in the main body mesh unit to the corresponding PBO fiber mesh and LCP fiber mesh on the escape-proof net unit using a specially designed high-strength waterproof zipper system. The connection structure is as follows: Figure 1 As shown, 2 and 3 are the connection and fixing positions, so as to facilitate the connection and fixing of the connection area between the two on the water.

[0114] The aforementioned high-strength waterproof zipper system is made of an alloy resistant to seawater corrosion (such as cupronickel), and its breaking strength exceeds that of the main mesh unit, achieving a "rigid-flexible" connection between the two. This ensures strength while allowing for a certain degree of relative deformation, avoiding stress concentration at hard connection points, and thus obtaining a connection system between the main mesh unit and the escape prevention net unit.

[0115] 2. Offshore construction and anchoring

[0116] (1) Use construction vessels to tow the pre-connected main netting unit-anti-escape netting unit connection system to the target sea area and deploy it between the corresponding pile foundations;

[0117] (2) Fix the top bar 15 of the main mesh unit to the fence walkway system, and fix the side bars 11 and 16 to the left and right pile foundations or to the transition connection system welded to the pile foundation (such as H-shaped galvanized alloy metal binding pipe).

[0118] (3) Install a counterweight chain on the lower line 14 of the main netting unit and connect and fix the counterweight chain to the bottom of the pile foundation on both sides with ropes; the counterweight chain is in contact with the seabed and is pressed and fixed with sandbags during construction to reduce displacement under the action of waves and currents; after the above construction procedures are completed, a main netting unit with a closed and fixed upper, left, right and bottom will be formed between two adjacent pile foundations in the pile foundation fence;

[0119] (4) A 12mm thick nitrile rubber pad 4 is installed on the side of the net that contacts the seabed of the escape-proof net unit; the rubber pad has high wear resistance and elasticity, and can effectively buffer the direct friction between the escape-proof net and the seabed mud, sand, reefs, etc., which is an innovative measure to extend the life of the net.

[0120] (5) The connecting lug 7 on the lower bar of the escape prevention net unit is dragged to the outside of the fence in a moderate manner, and connected to the pre-embedded basalt fiber composite reinforced concrete anchor block 6 by breaking the 57t strong carbon fiber pull chain 5; this bottom anchoring system of "anchor block-carbon fiber chain-escape prevention net" constitutes a flexible anchoring network that is deeply buried in the seabed and has high pull-out resistance, which greatly improves the overall stability of the entire offshore marine aquaculture pile foundation escape prevention net system under wind and waves.

[0121] (6) The construction personnel stitched the sides of the adjacent escape prevention net units together to form a continuous and integrated escape prevention barrier, thus constructing a high-nodular toughness escape prevention net system to prevent the escape of fish raised on offshore marine aquaculture pile foundation fences. This resulted in a high-nodular toughness escape prevention net for offshore marine aquaculture pile foundation fences.

[0122] 3. Systemic technical effects

[0123] After construction was completed, the high-nodulation toughness escape-prevention netting system for the offshore aquaculture pile foundation fence was continuously monitored for one year. It was also compared with an escape-prevention netting system using traditional PE netting material in adjacent waters (the comparison fence's escape-prevention netting and main netting were connected using a traditional permanent fixing method). The monitoring results showed that:

[0124] (1) Escape prevention reliability: Throughout the entire monitoring period, including two typhoon events, the high-nodular toughness escape prevention net system created in this invention did not experience any escape incidents of farmed organisms due to breakage, wear and tear, or connection failure of the net nodules. In contrast, in the comparative area, it was found that farmed fish escaped from the broken nodules after both typhoons.

[0125] (2) System operation and maintenance costs: Due to the excellent wear resistance, aging resistance, and anti-biofouling properties of the escape prevention net of this invention, no underwater repair or cleaning operations are required throughout the monitoring period. In contrast, the traditional PE netting escape prevention net in the comparative example requires 1-2 costly underwater cleaning and maintenance operations per year. It is estimated that the operation and maintenance costs of the high-nodular toughness escape prevention net system can be reduced by 40%-50% throughout its entire life cycle.

[0126] (3) Comprehensive Benefits: The high-nodularity toughness escape-proof net system created by this invention, due to its optimized hydrodynamic performance (high water flow rate), creates an unprecedentedly stable aquatic environment inside the offshore aquaculture pile-based enclosure. Water quality monitoring data shows that the dissolved oxygen distribution in the internal water is more uniform, and pollutants diffuse faster. Ultimately, the average growth rate of large yellow croakers raised in this offshore aquaculture pile-based enclosure increased by approximately 2.6% compared to the control enclosure, the feed conversion ratio decreased by approximately 1.7%, and the fish exhibited symmetrical body shape and healthy color, significantly increasing their commercial value. This proves that this invention not only solves the safety problem of "keeping aquaculture safe," but also creates ecological and economic value for "raising aquaculture well" through system optimization. The comprehensive benefits of the technical solution of this invention are significant.

[0127] The above embodiments fully verify the superiority of the technical solution provided by this invention in many aspects, including material design, process innovation, and system integration. The overall technical solution of this invention (especially the specific combination of material formulation and process parameters) produces a synergistic effect, solving long-standing technical biases or problems, thus possessing "non-obviousness." This invention successfully prepared a high-nodule toughness escape-proof net that perfectly matches many factors such as high strength, high nodule retention rate, excellent weather resistance, and suitability for the harsh offshore marine environment, along with its efficient connection method to the main netting, providing a reliable, efficient, and economical overall solution for offshore aquaculture fencing. Related tests in the East China Sea, Yellow Sea, and Bohai Sea areas show that the technical solution of this invention is feasible and has good technical effects. This invention provides an effective solution for improving the safety and reliability of escape-proof nets for offshore aquaculture fencing, contributing to the development of the fencing industry.

[0128] The undescribed parts of this invention are the same as or implemented using existing technology. The applicant declares that this invention is illustrated through the above embodiments, but the invention is not limited to the above detailed methods, i.e., it does not mean that the invention must rely on the above detailed methods to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A masterbatch for preparing escape-proof netting for offshore aquaculture pile foundation fencing, characterized in that, The preparation method includes the following steps: Deeply dried and pretreated raw materials are precisely mixed in the following weight proportions, followed by melt blending and underwater pelletizing: 70-80 parts HDPE, 15-25 parts UHMWPE, 3-10 parts POE, 0.8-1.2 parts compatibilizer, and 0.4-0.6 parts composite antioxidant. The conditions for melt blending and underwater pelletizing are as follows: The above premixed material is added to a co-rotating twin-screw extruder. To achieve optimal plasticization and dispersion, the temperatures of each section are precisely set as follows: Zone 1 165℃, Zone 2 185℃, Zone 3 225℃, Zone 4 245℃, and Zone 5 255℃; the screw speed is set to 210 rpm; after the melt is extruded through the multi-hole die, it is immediately quenched in a 25℃ constant temperature water bath, and then cut into cylindrical composite masterbatches by a pelletizer.

2. The masterbatch according to claim 1, characterized in that, The melt index of HDPE is 1.0 g / 10 min, the viscosity-average molecular weight of UHMWPE is 3.5 million, the compatibilizer is selected from PE-g-MAH, and the composite antioxidant is selected from antioxidant 1010 and 168 in a 1:1 mass ratio. The method for deep drying and pretreatment of raw materials is as follows: all raw materials are dried at 105℃±2℃ and -0.095MPa vacuum for 28 hours to ensure that the moisture content of the material is consistently below 120ppm. After drying, the material is immediately transferred to a sealed container filled with dry nitrogen for later use, and moisture reabsorption is strictly prevented. The original method for precise mixing is as follows: after mixing all raw materials according to the above weight proportions, put them into a high-speed mixer and strictly follow the step-by-step program of mixing at low speed of 350 rpm for 5 minutes and then mixing at high speed of 1050 rpm for 15 minutes.

3. A composite monofilament for preparing an escape-proof net for offshore aquaculture pile foundation fencing, characterized in that, The preparation method includes the following steps: the composite masterbatch prepared according to claim 1 or 2 is fed into a single-screw spinning mill, and the spinning temperature adopts a gradient heating strategy: zone 1 170℃ (feeding section), zone 2 190℃ (compression section), zone 3 220℃ (metering section), zone 4 235℃ (filtration section, using a 250-mesh filter), and zone 5 240℃ (spinneret section); the melt is transported to the spinneret by a precision metering pump to extrude nascent filaments, which are immediately placed in a constant temperature water bath at 25℃±0.5℃ for rapid cooling and solidification; subsequently, the solidified filaments are introduced into a non-aqueous liquid phase constant temperature medium at 110-120℃ for 10-14 times online thermal drawing to obtain the composite monofilament.

4. The composite monofilament according to claim 3, characterized in that: The spinneret has an orifice diameter of φ1.0mm; The non-aqueous liquid phase isothermal medium is dimethyl silicone oil, synthetic hydrocarbon hot oil, or mineral oil.

5. An escape-proof netting unit for offshore aquaculture pile foundation fencing, characterized in that, It is made from the multi-component composite monofilaments described in claim 3 or 4 through twisting into a net, weaving the net, heat setting, and assembly. The twisting of the network cable adopts at least one of the following standardized methods: Option A: Using 20 of the aforementioned composite monofilaments as one strand, perform initial twisting in the Z direction, and then perform S-direction retwisting of the three initial twisted strands to obtain a general-purpose high-strength network cable; Option B: Using 16 of the aforementioned composite monofilaments as one strand, the first strand is twisted in the Z direction, and the three strands of the first twisted strand are then twisted again in the S direction to obtain a highly flexible and fatigue-resistant network cable; Option C: Using 36 of the aforementioned composite monofilaments as a single strand, perform initial twisting in the Z direction, and then perform secondary twisting in the S direction on the three initial twisted strands to produce an extra-heavy-duty network cable. The mesh weaving and heat setting method is as follows: any twisted mesh yarn from schemes A to C is loaded into an intelligent knotless warp knitting machine. The mesh size is then set according to the body shape parameters of the target aquaculture species. During the weaving process, a closed-loop control system composed of integrated tension sensors monitors and maintains the specific tension of the mesh yarn at a constant 25N±1N~27±1N in real time. After weaving, the mesh is immediately sent to a heat setting unit for overall heat setting treatment at 120℃±3℃ for 30 minutes. The method for assembling the netting into an escape-proof netting unit is as follows: the escape-proof netting is cut and spliced ​​into a netting unit whose length matches the lower mesh size of the modular main netting unit. The netting unit is integrated and assembled with high-performance netting of different fiber materials for edge reinforcement. Connecting lugs for connecting with the anchoring structure of the modular main netting unit are provided on its bottom lower mesh, thus obtaining the escape-proof netting unit.

6. The escape-proof netting unit for offshore aquaculture pile foundation fencing according to claim 5, characterized in that, One LCP fiber net, one PBO fiber net, and one polyester-propylene fiber mixed net are installed on the upper line, 25-35cm below the upper line, and the lower line of the net unit, respectively. Mixed polyolefin nets are installed in other areas. The breaking strength of all nets is ≥51 tons.

7. A method for connecting the escape-proof netting to the main mesh of an offshore aquaculture pile foundation fence, characterized in that, Includes the following steps: S1: Provides a plurality of anti-escape net units as described in any one of claims 5-6; S2: Provides multiple modular main body mesh units, each equipped with a high-performance mesh. S3: The high-performance mesh of the escape prevention net unit is quickly connected to the corresponding mesh on the main net unit through a zipper system, thereby forming a main net unit-escape prevention net unit connection system.

8. The connection method according to claim 7, characterized in that, Before step S3, the method further includes: setting a wear-resistant buffer layer on the side of the netting that contacts the seabed of the escape-proof netting unit; After step S3, the method further includes: connecting the connecting lugs on the bottom lower strait of the escape prevention net unit to the anchoring structure buried on the seabed through a high-strength traction chain; The zipper system is a high-strength waterproof zipper made of an alloy material resistant to seawater corrosion, and its breaking strength is not lower than that of the mesh breaking strength of the main mesh unit.

9. An offshore marine aquaculture pile-based fencing escape prevention system, characterized in that, include: At least one escape-prevention net unit as described in any one of claims 5-6; At least one modular main mesh unit; The connection system of the main netting unit and the escape prevention netting unit is constructed by using the connection method of any one of claims 7-8.

10. The offshore marine aquaculture pile-based fencing escape prevention system according to claim 9, characterized in that, The escape prevention system is installed in a modular manner between adjacent piles of the pile foundation fence. The adjacent escape prevention net units are stitched together with HMPE stitching rope with a diameter of 4.2mm and double-stitched at a stitch spacing of 120mm. The number of stitches per centimeter at the stitching is kept stable at 3.

5. A 0.5mm thick HMPE woven fabric protective cover is added to the connection point and stitched together to form a continuous and integrated escape prevention barrier.

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