A modified high-elasticity bale net and a preparation process thereof

Abstract

This invention relates to the field of polyethylene material technology, specifically to a modified high-elasticity straw wrapping mesh and its preparation process. This invention achieves a comprehensive and balanced improvement in mechanical properties, flame retardancy, anti-aging properties, and processing performance through a multi-component synergistic design of a high-density polyethylene matrix combined with an epoxy-functionalized ethylene-octene copolymer, maleic anhydride-grafted polyethylene, organically modified wollastonite, composite flame retardants, and composite anti-aging components. This effectively solves the technical problem that traditional high-density polyethylene-based straw wrapping mesh cannot simultaneously achieve elasticity, strength, flame retardancy, and weather resistance. When the material is subjected to external force, the stress is effectively transferred to the rigid wollastonite-reinforced skeleton through the "molecular bridge" of the maleic anhydride-grafted polyethylene, with the skeleton bearing the main load. Simultaneously, the flexible epoxy-functionalized ethylene-octene copolymer phase absorbs and dissipates excess stress through large deformation, preventing rapid crack propagation.

Description

Technical Field

[0001] This invention relates to the field of polyethylene material technology, specifically to a modified high-elasticity straw net and its preparation process. Background Technology

[0002] Hay bale netting, also known as hay baling netting or forage netting, is a key packaging material in modern agriculture used for baling and wrapping hay, straw, and other crops. It is made by weaving high-molecular yarns into a mesh structure using warp knitting technology, wrapping the bale of hay to fix its shape, prevent scattering, and promote silage fermentation. Currently, commercially available hay bale netting is mainly made of high-density polyethylene or polypropylene resin through melt spinning, stretching, and shaping. However, traditional high-density polyethylene-based hay bale netting, due to its regular molecular chain structure, high crystallinity, and low elongation at break, cannot adapt to the volume rebound of the hay during baling, resulting in inconsistent wrapping tightness or even unbundling. While adding elastomers such as ethylene-octene copolymers to high-density polyethylene can improve flexibility, it leads to a decrease in material rigidity and a significant reduction in tensile strength. The inherent contradiction between strength and elasticity has long remained unresolved.

[0003] Furthermore, existing straw-covering nets, when used outdoors for extended periods, suffer from embrittlement and fracture due to UV exposure and thermo-oxidative aging, limiting their lifespan. Additionally, there are fire hazards during straw storage, as traditional high-density polyethylene straw-covering nets are flammable materials; once ignited, they burn rapidly and produce molten droplets, easily igniting surrounding straw and spreading the fire. To address these issues, existing technologies have attempted single-function modifications by adding toughening agents, flame retardants, or antioxidants, but these often compromise overall performance. The introduction of flame retardants degrades mechanical properties and aging resistance, while the addition of toughening agents reduces strength and flame-retardant efficiency. The lack of compatibility design between functional components makes it difficult to achieve a comprehensive improvement in elasticity, strength, flame retardancy, and weather resistance. To address these technical deficiencies in existing straw-covering nets, this invention provides a modified, highly elastic straw-covering net and its preparation process. Summary of the Invention

[0004] Technical problems to be solved To address the aforementioned shortcomings of existing technologies, this invention provides a modified high-elasticity straw net and its preparation process, which effectively solves the problem that traditional high-density polyethylene-based straw nets cannot simultaneously achieve elasticity, strength, flame retardancy, and weather resistance. Technical solution

[0005] To achieve the above objectives, the present invention provides the following technical solution: A modified high-elasticity straw net is composed of the following components: high-density polyethylene, epoxy-functionalized ethylene-octene copolymer, maleic anhydride-grafted polyethylene, organic modified wollastonite, composite flame retardant and composite anti-aging component. The epoxy-functionalized ethylene-octene copolymer is prepared by grafting glycidyl methacrylate onto an ethylene-octene copolymer. The maleic anhydride-grafted polyethylene is prepared by grafting maleic anhydride onto low-density polyethylene. The organically modified wollastonite is prepared by modifying wollastonite powder with phthalate coupling agent; The composite flame retardant is prepared by mixing triphenyl phosphate, melamine polyphosphate, pentaerythritol and organically modified montmorillonite. The composite anti-aging component is prepared by mixing a main antioxidant, a secondary antioxidant, and a light stabilizer.

[0006] Furthermore, the grafting rate of the epoxy-functionalized ethylene-octene copolymer is 2-3%.

[0007] The preparation method of the epoxy-functionalized ethylene-octene copolymer is as follows: 100 parts by weight of ethylene-octene copolymer, 4-6 parts by weight of glycidyl methacrylate, 1-3 parts by weight of styrene, and 0.3-0.8 parts by weight of dicumyl peroxide are weighed and mixed, and then a melt grafting reaction is carried out in a twin-screw extruder. After extrusion, the mixture is cooled by water and granulated to obtain the epoxy-functionalized ethylene-octene copolymer. In the melt grafting reaction, the screw speed of the twin-screw extruder is 60 r / min, and the temperature of each section is set to 170℃, 170℃, 180℃, 180℃, 180℃, 180℃, 180℃ (die head temperature).

[0008] Furthermore, the grafting rate of the maleic anhydride-grafted polyethylene is 1-2%.

[0009] The preparation method of maleic anhydride-grafted polyethylene is as follows: 100 parts by weight of low-density polyethylene and 800 parts by weight of xylene are added to a three-necked flask, stirred and heated to 95-110°C, and then 8-10 parts by weight of maleic anhydride are added. Then, 0.5-0.8 parts by weight of dicumyl peroxide and 1.5-2 parts by weight of caprolactam are added. After stirring and reacting for 3 hours, the mixture is cooled to 65-70°C and 1000 parts by weight of acetone are added. The mixture is stirred at a stirring speed of 800-1000 r / min, filtered, and washed 3 times with acetone. After drying in an oven at 70-75°C, the resulting product is maleic anhydride-grafted polyethylene.

[0010] Furthermore, the preparation method of the organically modified wollastonite is as follows: Place 800-1500 mesh wollastonite powder in a high-speed mixer, add 2-3% by weight of titanate coupling agent, and stir at 110-130℃ and 800-1000 r / min for 15-25 min to obtain organic modified wollastonite.

[0011] Furthermore, the preparation method of the organically modified montmorillonite is as follows: The pH of 100 parts by weight of 90% ethanol aqueous solution was adjusted to 3-4 using a 1% acetic acid solution. 4-9 parts by weight of silane coupling agent KH-560 were added, and the mixture was stirred and hydrolyzed for 4 hours. Then, 10 parts by weight of montmorillonite were added, and the mixture was heated under reflux at 70-90℃ for 24 hours. After cooling to room temperature and filtering, the mixture was washed 3-5 times with anhydrous ethanol and dried in a vacuum drying oven at 90℃. The mixture was then reacted in a supercritical CO2 reactor at 40-80℃ and 20MPa for 2 hours. Finally, the mixture was washed sequentially with deionized water and anhydrous ethanol and dried in a vacuum drying oven at 90℃ for 24 hours. The resulting product is organically modified montmorillonite.

[0012] Furthermore, the composite flame retardant is prepared by mixing triphenyl phosphate, melamine polyphosphate, pentaerythritol and organic modified montmorillonite in a weight ratio of (5-10):(3-5):(2-4):(1-2) and stirring at 800 r / min for 15 min at room temperature.

[0013] Furthermore, the primary antioxidant is antioxidant 1010, the secondary antioxidant is antioxidant 168, and the light stabilizer is light stabilizer 944; The composite anti-aging component is prepared by mixing antioxidant 1010, antioxidant 168 and light stabilizer 944 in a weight ratio of 1:2:(3-5) and stirring at 500 r / min for 10 min at room temperature.

[0014] A preparation process for a modified high-elasticity straw net, the preparation process comprising the following steps: S1. Weigh 100 parts by weight of high-density polyethylene, 30-40 parts by weight of epoxy-functionalized ethylene-octene copolymer, 10-15 parts by weight of maleic anhydride-grafted polyethylene, 15-25 parts by weight of organic modified wollastonite, 20-30 parts by weight of composite flame retardant and 0.6-1.2 parts by weight of composite anti-aging component and pour them into a high-speed mixer for premixing. The result is called premix. S2. Add the premixed material to a twin-screw extruder for melt blending. The screw speed is 250 r / min, and the temperature of each section is set to 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, and 190℃ (die head temperature). After extrusion, the material is water-cooled, stretched, and pelletized. It is then placed in a vacuum drying oven at 85℃ for 8 hours to dry. The resulting material is recorded as premixed material granules. S3. Add the premixed granules into a single-screw extruder, and after extrusion and stretching into a film and splitting into filaments, obtain film filament yarn; S4. After the membrane yarn is hot-stretched and shaped, it is woven and finally annealed to obtain the modified high-elasticity straw net.

[0015] Furthermore, the method for extrusion stretching into film and fiber separation in S3 is as follows: The extrusion temperature is set to 180-200℃, with zone 1 at 180℃, zone 2 at 190℃, zone 3 at 200℃, and the die head at 195℃. The film is cast through a T-die, with the film thickness controlled at 0.08-0.12mm. After being cooled by a cooling roller at 25℃, the cast film enters a slitting device and is cut by blades into film yarns with a width of 1.5-2.5mm.

[0016] Furthermore, the method for heat stretching and setting in S4 is as follows: The film yarn is placed in a hot stretching unit at 100℃ and a stretch ratio of 5 for hot stretching and setting. The total stretch rate of the yarn is controlled at 40-60%. The stretched yarn is treated by a hot setting roller at 80℃ for 10 seconds, and then cooled and wound up by a cooling roller. The result is the hot stretching and setting yarn. The weaving process in S4 is as follows: the heat-stretched and set yarn is divided into warp and weft yarns, and then woven on a Raschel warp knitting machine. The warp yarns are arranged in parallel, and the weft yarns are interlaced between the warp yarns in a serrated pattern. The weaving parameters are: warp density 40-60 ends / inch, weft density 20-30 ends / inch. The yarn junctions are fixed by heat bonding. The heat bonding temperature is 130-150℃, the pressure is 0.3-0.4MPa, and the heat pressing time is 2-3s. The annealing heat treatment method in S4 is as follows: anneal at 90℃ for 20 minutes, and then naturally cool to room temperature.

[0017] Beneficial effects This invention provides a modified high-elasticity straw net and its preparation process. Compared with existing technologies, this invention has the following advantages: High-density polyethylene, epoxy-functionalized ethylene-octene copolymer, maleic anhydride-grafted polyethylene, organically modified wollastonite, composite flame retardant and composite anti-aging component 1. The epoxy-functionalized ethylene-octene copolymer in this invention forms a micron-scale elastomer dispersion phase within a high-density polyethylene matrix. Its soft octene segments endow the material with excellent elastic deformation capabilities and simultaneously act as stress concentration points, inducing crazes and shear bands to effectively absorb and dissipate impact energy. Organically modified wollastonite, a needle-like silicate filler, aligns along the flow direction during processing, forming a "microfiber"-like rigid reinforcing skeleton in the matrix, effectively bearing and transferring loads. The maleic anhydride groups of maleic anhydride-grafted polyethylene chemically bond with the active groups formed by the titanate coupling agent treatment layer on the wollastonite surface. Simultaneously, its polyethylene backbone exhibits good compatibility with the high-density polyethylene matrix, thus establishing a "molecular bridge" between the polar wollastonite and the non-polar high-density polyethylene / ethylene-octene copolymer matrix.

[0018] When the material is subjected to external force, the stress is effectively transferred to the rigid wollastonite-reinforced skeleton through the "molecular bridge" of maleic anhydride-grafted polyethylene, and the skeleton bears the main load. At the same time, the flexible epoxy-functionalized ethylene-octene copolymer phase absorbs and dissipates excess stress through large deformation, preventing the rapid propagation of cracks. The above mechanism enables the tensile strength and elongation at break of the material to be improved simultaneously, breaking the traditional thermoplastic material performance contradiction of "strength increases inevitably reduce toughness, and toughening inevitably reduces strength".

[0019] 2. The glycidyl methacrylate grafted onto the epoxy-functionalized ethylene-octene copolymer molecular chain of this invention contains highly reactive epoxy groups. During melt blending, these epoxy groups can undergo ring-opening reactions with the hydroxyl groups remaining on the surface of organically modified wollastonite and the polyhydroxyl groups of pentaerythritol, forming chemical bonds. Similarly, the anhydride groups of maleic anhydride grafted onto polyethylene can undergo esterification reactions with the aforementioned hydroxyl groups. The epoxy groups of glycidyl methacrylate and the anhydride groups of maleic anhydride form a "bifunctional complementary" interfacial anchoring mode: the reactivity of the epoxy groups with the hydroxyl groups is higher than that of the anhydride with the hydroxyl groups in the esterification reaction. The two complement each other under different reaction conditions, resulting in a strong chemical bond between the filler and the matrix, and between the flame retardant and the matrix, rather than a simple physical dispersion.

[0020] The result of the above-mentioned dual-mode chemical anchoring is that the originally polar inorganic / organic filler and the originally non-polar high-density polyethylene matrix are connected in an "integrated" manner through chemical bonds, which significantly reduces the interfacial tension and avoids the agglomeration and migration of the filler during processing and use, thereby improving the mechanical properties and flame retardant properties of the material at the same time.

[0021] 3. The four components of the composite flame retardant in this invention can form a four-source integrated expansion flame retardant synergistic network of "acid source-carbon source-gas source-reinforcing source"; when heated, melamine polyphosphate decomposes to release phosphoric acid and non-combustible gas, phosphoric acid catalyzes the dehydration of pentaerythritol to form char, triphenyl phosphate participates in char formation and enhances the thermal stability of the char layer, and non-combustible gas drives the char layer to expand to form a porous heat insulation layer; at the same time, the silicate sheets of organically modified montmorillonite migrate to the surface to form a dense inorganic protective layer on the surface of the expanded char layer; the above three processes of acid-catalyzed char formation, gas expansion and physical barrier work together to make the final expanded char layer have thickness, density and thermal stability, and can quickly build an effective heat insulation and oxygen barrier on the material surface to achieve the self-extinguishing and anti-dripping properties of the material.

[0022] 4. In this invention, antioxidant 168, as a phosphite-based auxiliary antioxidant, preferentially decomposes hydrogen peroxide during the melt processing stage, inhibiting thermal oxidative degradation and protecting the molecular weight of the matrix; antioxidant 1010, as a hindered phenolic primary antioxidant, captures alkyl free radicals and peroxy free radicals during use, effectively terminating the oxidation chain reaction, and the continuous protection provided by antioxidant 168 ensures its long-term activity, forming a synergistic effect between the two; light stabilizer 944, as a high molecular weight hindered amine light stabilizer, captures photo-oxidative free radicals and quenches singlet oxygen through its piperidine ring structure, inhibiting UV-induced oxidative degradation, and its high molecular weight ensures long-term migration resistance. The three components respectively cover the processing, use, and outdoor exposure stages, forming a complete and progressive protective chain, enabling the straw net to obtain comprehensive anti-aging protection throughout its entire life cycle. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] The present invention will be further described below with reference to embodiments. Example 1

[0025] This embodiment describes a preparation process for a modified high-elasticity straw net. In the preliminary preparation work, the following components are prepared: high-density polyethylene, epoxy-functionalized ethylene-octene copolymer, maleic anhydride-grafted polyethylene, organically modified wollastonite, composite flame retardant, and composite anti-aging component.

[0026] The epoxy-functionalized ethylene-octene copolymer is prepared by grafting glycidyl methacrylate onto the ethylene-octene copolymer, with a grafting rate of 2.5%. The specific preparation method is as follows: Weigh out 100 parts by weight of ethylene-octene copolymer, 5 parts by weight of glycidyl methacrylate, 2 parts by weight of styrene, and 0.5 parts by weight of dicumyl peroxide and mix them. Then, carry out a melt grafting reaction in a twin-screw extruder. After extrusion, the mixture is cooled by water and granulated to obtain epoxy-functionalized ethylene-octene copolymer. The screw speed of the twin-screw extruder in the melt grafting reaction is 60 r / min, and the temperature of each section is set to 170℃, 170℃, 180℃, 180℃, 180℃, 180℃, 180℃ (die head temperature).

[0027] Maleic anhydride-grafted polyethylene is prepared by grafting maleic anhydride onto low-density polyethylene, with a grafting rate of 1.5%. The specific preparation method is as follows: 100 parts by weight of low-density polyethylene and 800 parts by weight of xylene are added to a three-necked flask, stirred and heated to 105°C, then 9 parts by weight of maleic anhydride are added, followed by 0.7 parts by weight of dicumyl peroxide and 1.8 parts by weight of caprolactam. After stirring and reacting for 3 hours, the mixture is cooled to 68°C and 1000 parts by weight of acetone are added. The mixture is stirred at a stirring speed of 900 r / min, filtered, and washed three times with acetone. After drying in an oven at 72°C, the resulting product is maleic anhydride-grafted polyethylene.

[0028] Organically modified wollastonite is prepared by modifying wollastonite powder with phthalic acid ester coupling agent. The preparation method is as follows: Place 1200-mesh wollastonite powder in a high-speed mixer, add 3% by weight of titanate coupling agent, and stir at 120°C and 900 r / min for 20 min to obtain organic modified wollastonite.

[0029] The composite flame retardant is prepared by mixing triphenyl phosphate, melamine polyphosphate, pentaerythritol and organically modified montmorillonite. The preparation method of organically modified montmorillonite is as follows: The pH of 100 parts by weight of 90% ethanol aqueous solution was adjusted to 4 using a 1% acetic acid solution. 7 parts by weight of silane coupling agent KH-560 were added, and the mixture was stirred and hydrolyzed for 4 hours. Then, 10 parts by weight of montmorillonite were added, and the mixture was heated under reflux at 80°C for 24 hours. After cooling to room temperature and filtering, the mixture was washed four times with anhydrous ethanol and dried in a vacuum drying oven at 90°C. The mixture was then reacted in a supercritical CO2 reactor at 60°C and 20 MPa for 2 hours. Finally, the mixture was washed sequentially with deionized water and anhydrous ethanol and dried in a vacuum drying oven at 90°C for 24 hours. The resulting product is organically modified montmorillonite.

[0030] The composite flame retardant was prepared by mixing triphenyl phosphate, melamine polyphosphate, pentaerythritol and organic modified montmorillonite in a weight ratio of 8:4:3:1 and stirring at 800 r / min for 15 min at room temperature.

[0031] The composite anti-aging component is prepared by mixing a main antioxidant, a secondary antioxidant, and a light stabilizer. The main antioxidant is antioxidant 1010, the secondary antioxidant is antioxidant 168, and the light stabilizer is light stabilizer 944. The composite anti-aging component is prepared by mixing antioxidant 1010, antioxidant 168 and light stabilizer 944 in a weight ratio of 1:2:4 and stirring at 500 r / min for 10 min at room temperature.

[0032] After the preliminary preparations are completed, the following preparation steps will be performed: S1. Weigh 100 parts by weight of high-density polyethylene, 35 parts by weight of epoxy-functionalized ethylene-octene copolymer, 12 parts by weight of maleic anhydride grafted polyethylene, 20 parts by weight of organic modified wollastonite, 25 parts by weight of composite flame retardant and 0.8 parts by weight of composite anti-aging component and pour them into a high-speed mixer for premixing. The result is called premix. S2. Add the premixed material to a twin-screw extruder for melt blending. The screw speed is 250 r / min, and the temperature of each section is set to 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, and 190℃ (die head temperature). After extrusion, the material is water-cooled, stretched, and pelletized. It is then placed in a vacuum drying oven at 85℃ for 8 hours to dry. The resulting material is recorded as premixed material granules. S3. Add the premixed granules into a single-screw extruder. Set the extrusion temperature to 190℃, with zone 1 at 180℃, zone 2 at 190℃, zone 3 at 200℃, and the die at 195℃. Cast the film through a T-die, with the film thickness controlled at 0.1mm. After being cooled by a cooling roller at 25℃, the cast film enters a slitting device and is cut into 2mm wide film yarns by blades. S4. After the membrane yarn is hot-stretched and shaped, it is woven and finally annealed to obtain the modified high-elasticity straw net.

[0033] The method for heat stretching and setting is as follows: The film yarn is placed in a hot stretching unit at 100℃ and a stretch ratio of 5 times for hot stretching and setting. The total stretch rate of the yarn is controlled at 50%. The stretched yarn is treated by a hot setting roller at 80℃ for 10 seconds, and then cooled and wound up by a cooling roller. The result is the hot stretching and setting yarn. The weaving process is as follows: The heat-stretched and set yarns are divided into warp and weft yarns, and then woven on a Raschel warp knitting machine. The warp yarns are arranged in parallel, and the weft yarns are interwoven in a serrated pattern between the warp yarns. The weaving parameters are: warp density 50 threads / inch, weft density 25 threads / inch. The yarn junctions are fixed by heat bonding. The heat bonding temperature is 140℃, the pressure is 0.4MPa, and the heat pressing time is 3s. The method of annealing heat treatment is as follows: Anneal at 90°C for 20 minutes, then allow to cool naturally to room temperature.

[0034] Example 2 This embodiment describes a preparation process for a modified high-elasticity straw net. In the preliminary preparation work, the following components are prepared: high-density polyethylene, epoxy-functionalized ethylene-octene copolymer, maleic anhydride-grafted polyethylene, organically modified wollastonite, composite flame retardant, and composite anti-aging component.

[0035] The epoxy-functionalized ethylene-octene copolymer is prepared by grafting glycidyl methacrylate onto the ethylene-octene copolymer, with a grafting rate of 2%. The specific preparation method is as follows: Weigh out 100 parts by weight of ethylene-octene copolymer, 4 parts by weight of glycidyl methacrylate, 1 part by weight of styrene, and 0.3 parts by weight of dicumyl peroxide and mix them. Then, carry out a melt grafting reaction in a twin-screw extruder. After extrusion, the mixture is cooled by water and granulated to obtain epoxy-functionalized ethylene-octene copolymer. The screw speed of the twin-screw extruder in the melt grafting reaction is 60 r / min, and the temperature of each section is set to 170℃, 170℃, 180℃, 180℃, 180℃, 180℃, 180℃ (die head temperature).

[0036] Maleic anhydride-grafted polyethylene is prepared by grafting maleic anhydride onto low-density polyethylene, with a grafting rate of 1%. The specific preparation method is as follows: 100 parts by weight of low-density polyethylene and 800 parts by weight of xylene are added to a three-necked flask, stirred and heated to 95°C, then 8 parts by weight of maleic anhydride are added, followed by 0.5 parts by weight of dicumyl peroxide and 1.5 parts by weight of caprolactam. After stirring and reacting for 3 hours, the mixture is cooled to 65°C and 1000 parts by weight of acetone are added. The mixture is stirred at 800 r / min, filtered, and washed three times with acetone. After drying in an oven at 70°C, the resulting product is maleic anhydride-grafted polyethylene.

[0037] Organically modified wollastonite is prepared by modifying wollastonite powder with phthalic acid ester coupling agent. The preparation method is as follows: Place 800-mesh wollastonite powder in a high-speed mixer, add 2% by weight of titanate coupling agent, and stir at 110°C and 800 r / min for 15 min to obtain organic modified wollastonite.

[0038] The composite flame retardant is prepared by mixing triphenyl phosphate, melamine polyphosphate, pentaerythritol and organically modified montmorillonite. The preparation method of organically modified montmorillonite is as follows: The pH of 100 parts by weight of 90% ethanol aqueous solution was adjusted to 3 using a 1% acetic acid solution. 4 parts by weight of silane coupling agent KH-560 were added, and the mixture was stirred and hydrolyzed for 4 hours. Then, 10 parts by weight of montmorillonite were added, and the mixture was heated under reflux at 70°C for 24 hours. After cooling to room temperature and filtering, the mixture was washed three times with anhydrous ethanol and dried in a vacuum drying oven at 90°C. The mixture was then reacted in a supercritical CO2 reactor at 40°C and 20 MPa for 2 hours. Finally, the mixture was washed sequentially with deionized water and anhydrous ethanol and dried in a vacuum drying oven at 90°C for 24 hours. The resulting product is organically modified montmorillonite.

[0039] The composite flame retardant was prepared by mixing triphenyl phosphate, melamine polyphosphate, pentaerythritol and organic modified montmorillonite in a weight ratio of 5:3:2:1 and stirring at 800 r / min for 15 min at room temperature.

[0040] The composite anti-aging component is prepared by mixing a main antioxidant, a secondary antioxidant, and a light stabilizer. The main antioxidant is antioxidant 1010, the secondary antioxidant is antioxidant 168, and the light stabilizer is light stabilizer 944. The composite anti-aging component is prepared by mixing antioxidant 1010, antioxidant 168 and light stabilizer 944 in a weight ratio of 1:2:3 and stirring at 500 r / min for 10 min at room temperature.

[0041] After the preliminary preparations are completed, the following preparation steps will be performed: S1. Weigh 100 parts by weight of high-density polyethylene, 30 parts by weight of epoxy-functionalized ethylene-octene copolymer, 10 parts by weight of maleic anhydride grafted polyethylene, 15 parts by weight of organic modified wollastonite, 20 parts by weight of composite flame retardant and 0.6 parts by weight of composite anti-aging component and pour them into a high-speed mixer for premixing. The result is called premix. S2. Add the premixed material to a twin-screw extruder for melt blending. The screw speed is 250 r / min, and the temperature of each section is set to 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, and 190℃ (die head temperature). After extrusion, the material is water-cooled, stretched, and pelletized. It is then placed in a vacuum drying oven at 85℃ for 8 hours to dry. The resulting material is recorded as premixed material granules. S3. Add the premixed granules into a single-screw extruder. Set the extrusion temperature to 180℃, with zone 1 at 180℃, zone 2 at 190℃, zone 3 at 200℃, and the die at 195℃. Cast the film through a T-die, with the film thickness controlled at 0.08mm. After being cooled by a cooling roller at 25℃, the cast film enters a slitting device and is cut into 1.5mm wide film yarns by blades. S4. After the membrane yarn is hot-stretched and shaped, it is woven and finally annealed to obtain the modified high-elasticity straw net.

[0042] The method for heat stretching and setting is as follows: The film yarn is placed in a hot stretching unit at 100℃ and a stretch ratio of 5 for hot stretching and setting. The total stretch rate of the yarn is controlled at 40%. The stretched yarn is treated by a hot setting roller at 80℃ for 10 seconds, and then cooled and wound up by a cooling roller. The result is the hot stretching and setting yarn. The weaving process is as follows: The heat-stretched and set yarns are divided into warp and weft yarns, and then woven on a Raschel warp knitting machine. The warp yarns are arranged in parallel, and the weft yarns are interwoven between the warp yarns in a serrated pattern. The weaving parameters are: warp density 40 yarns / inch, weft density 20 yarns / inch. The yarn junctions are fixed by heat bonding. The heat bonding temperature is 130℃, the pressure is 0.3MPa, and the heat pressing time is 2s. The method of annealing heat treatment is as follows: Anneal at 90°C for 20 minutes, then allow to cool naturally to room temperature.

[0043] Example 3 This embodiment describes a preparation process for a modified high-elasticity straw net. In the preliminary preparation work, the following components are prepared: high-density polyethylene, epoxy-functionalized ethylene-octene copolymer, maleic anhydride-grafted polyethylene, organically modified wollastonite, composite flame retardant, and composite anti-aging component.

[0044] The epoxy-functionalized ethylene-octene copolymer is prepared by grafting glycidyl methacrylate onto the ethylene-octene copolymer, with a grafting rate of 3%. The specific preparation method is as follows: Weigh out 100 parts by weight of ethylene-octene copolymer, 6 parts by weight of glycidyl methacrylate, 3 parts by weight of styrene, and 0.8 parts by weight of dicumyl peroxide and mix them. Then, carry out a melt grafting reaction in a twin-screw extruder. After extrusion, the mixture is cooled by water and granulated to obtain epoxy-functionalized ethylene-octene copolymer. The screw speed of the twin-screw extruder in the melt grafting reaction is 60 r / min, and the temperature of each section is set to 170℃, 170℃, 180℃, 180℃, 180℃, 180℃, 180℃ (die head temperature).

[0045] Maleic anhydride-grafted polyethylene is prepared by grafting maleic anhydride onto low-density polyethylene, with a grafting rate of 2%. The specific preparation method is as follows: 100 parts by weight of low-density polyethylene and 800 parts by weight of xylene are added to a three-necked flask, stirred and heated to 110°C, then 10 parts by weight of maleic anhydride are added, followed by 0.8 parts by weight of dicumyl peroxide and 2 parts by weight of caprolactam. After stirring and reacting for 3 hours, the mixture is cooled to 70°C and 1000 parts by weight of acetone are added. The mixture is stirred at a stirring speed of 1000 r / min, filtered, and washed three times with acetone. After drying in an oven at 75°C, the resulting product is maleic anhydride-grafted polyethylene.

[0046] Organically modified wollastonite is prepared by modifying wollastonite powder with phthalic acid ester coupling agent. The preparation method is as follows: Place 1500-mesh wollastonite powder in a high-speed mixer, add 3% by weight of titanate coupling agent, and stir at 1000 r / min for 25 min at 130℃. The result is organic modified wollastonite.

[0047] The composite flame retardant is prepared by mixing triphenyl phosphate, melamine polyphosphate, pentaerythritol and organically modified montmorillonite. The preparation method of organically modified montmorillonite is as follows: The pH of 100 parts by weight of 90% ethanol aqueous solution was adjusted to 4 using a 1% acetic acid solution. Nine parts by weight of silane coupling agent KH-560 were added, and the mixture was stirred and hydrolyzed for 4 hours. Then, 10 parts by weight of montmorillonite were added, and the mixture was heated under reflux at 90°C for 24 hours. After cooling to room temperature and filtering, the mixture was washed five times with anhydrous ethanol and dried in a vacuum drying oven at 90°C. The mixture was then reacted in a supercritical CO2 reactor at 80°C and 20 MPa for 2 hours. Finally, the mixture was washed sequentially with deionized water and anhydrous ethanol and dried in a vacuum drying oven at 90°C for 24 hours. The resulting product is organically modified montmorillonite.

[0048] The composite flame retardant was prepared by mixing triphenyl phosphate, melamine polyphosphate, pentaerythritol and organic modified montmorillonite in a weight ratio of 10:5:4:2 and stirring at 800 r / min for 15 min at room temperature.

[0049] The composite anti-aging component is prepared by mixing a main antioxidant, a secondary antioxidant, and a light stabilizer. The main antioxidant is antioxidant 1010, the secondary antioxidant is antioxidant 168, and the light stabilizer is light stabilizer 944. The composite anti-aging component is prepared by mixing antioxidant 1010, antioxidant 168 and light stabilizer 944 in a weight ratio of 1:2:5 and stirring at 500 r / min for 10 min at room temperature.

[0050] After the preliminary preparations are completed, the following preparation steps will be performed: S1. Weigh 100 parts by weight of high-density polyethylene, 40 parts by weight of epoxy-functionalized ethylene-octene copolymer, 15 parts by weight of maleic anhydride grafted polyethylene, 25 parts by weight of organic modified wollastonite, 30 parts by weight of composite flame retardant and 1.2 parts by weight of composite anti-aging component and pour them into a high-speed mixer for premixing. The result is called premix. S2. Add the premixed material to a twin-screw extruder for melt blending. The screw speed is 250 r / min, and the temperature of each section is set to 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, and 190℃ (die head temperature). After extrusion, the material is water-cooled, stretched, and pelletized. It is then placed in a vacuum drying oven at 85℃ for 8 hours to dry. The resulting material is recorded as premixed material granules. S3. Add the premixed granules into a single-screw extruder. Set the extrusion temperature to 200℃, with zone 1 at 180℃, zone 2 at 190℃, zone 3 at 200℃, and the die head at 195℃. Cast the film through a T-die, with the film thickness controlled at 0.12mm. After being cooled by a cooling roller at 25℃, the cast film enters a slitting device and is slitted into 2.5mm wide film yarns by blades. S4. After the membrane yarn is hot-stretched and shaped, it is woven and finally annealed to obtain the modified high-elasticity straw net.

[0051] The method for heat stretching and setting is as follows: The film yarn is placed in a hot stretching unit at 100℃ and a stretch ratio of 5 for hot stretching and setting. The total stretch rate of the yarn is controlled at 60%. The stretched yarn is treated by a hot setting roller at 80℃ for 10 seconds, and then cooled and wound up by a cooling roller. The result is the hot stretching and setting yarn. The weaving process is as follows: The heat-stretched and set yarns are divided into warp and weft yarns, and then woven on a Raschel warp knitting machine. The warp yarns are arranged in parallel, and the weft yarns are interwoven between the warp yarns in a serrated pattern. The weaving parameters are: warp density 60 threads / inch, weft density 30 threads / inch. The yarn junctions are fixed by heat bonding. The heat bonding temperature is 150℃, the pressure is 0.4MPa, and the heat pressing time is 3s. The method of annealing heat treatment is as follows: Anneal at 90°C for 20 minutes, then allow to cool naturally to room temperature.

[0052] Comparative Example 1 This comparative example is a straw net made of pure high-density polyethylene, which does not contain epoxy-functionalized ethylene-octene copolymer, maleic anhydride-grafted polyethylene, organic modified wollastonite, composite flame retardant and composite anti-aging component. The preparation process is the same as in Example 1.

[0053] Comparative Example 2

[0054] The difference between this comparative example and Example 1 is that the formulation does not contain epoxy-functionalized ethylene-octene copolymer, while the remaining components and preparation process are the same as in Example 1. Specifically, in S1, 100 parts by weight of high-density polyethylene, 12 parts by weight of maleic anhydride-grafted polyethylene, 20 parts by weight of organically modified wollastonite, 25 parts by weight of composite flame retardant, and 0.8 parts by weight of composite anti-aging component are weighed and premixed.

[0055] Comparative Example 3 The difference between this comparative example and Example 1 is that the formulation does not contain maleic anhydride-grafted polyethylene, while the remaining components and preparation process are the same as in Example 1. Specifically, in S1, 100 parts by weight of high-density polyethylene, 35 parts by weight of epoxy-functionalized ethylene-octene copolymer, 20 parts by weight of organically modified wollastonite, 25 parts by weight of composite flame retardant, and 0.8 parts by weight of composite anti-aging component are weighed and premixed.

[0056] Comparative Example 4 The difference between this comparative example and Example 1 is that the formulation does not contain a composite flame retardant, while the remaining components and preparation process are the same as in Example 1. Specifically, in S1, 100 parts by weight of high-density polyethylene, 35 parts by weight of epoxy-functionalized ethylene-octene copolymer, 12 parts by weight of maleic anhydride-grafted polyethylene, 20 parts by weight of organically modified wollastonite, and 0.8 parts by weight of composite anti-aging component are weighed and premixed.

[0057] Comparative Example 5 The difference between this comparative example and Example 1 is that the formulation does not contain the composite anti-aging component, while the remaining components and preparation process are the same as in Example 1. Specifically, in S1, 100 parts by weight of high-density polyethylene, 35 parts by weight of epoxy-functionalized ethylene-octene copolymer, 12 parts by weight of maleic anhydride-grafted polyethylene, 20 parts by weight of organically modified wollastonite, and 25 parts by weight of composite flame retardant are weighed and premixed.

[0058] Performance Testing and Result Analysis The following performance tests were conducted on the straw nets prepared in Examples 1-3 and Comparative Examples 1-5: 1. Mechanical property testing: Tensile strength and elongation at break were tested according to GB / T1040.3-2006 standard, with a specimen width of 15 mm and a tensile rate of 200 mm / min; right-angle tear strength was tested according to QB / T1130-1991 standard. 2. Flame retardant performance testing: Limiting oxygen index (LOI) is tested according to GB / T2406.2-2009 standard; vertical flammability rating is tested according to UL-94 standard. 3. Anti-aging performance test: Ultraviolet aging test (irradiation intensity 0.76W / m²@340nm, black panel temperature 60℃, continuous irradiation for 1000h) was conducted according to GB / T16422.2-2014 standard to test the retention rate of tensile strength and elongation at break after aging; thermal aging test (80℃×720h) was conducted according to GB / T7141-2008 standard to test the retention rate of tensile strength after aging. 4. Processing performance test: The melt flow rate (MFR) was tested at 190℃ and 2.16kg load according to GB / T3682-2000 standard; the processing performance was evaluated based on the weaving efficiency under normal production conditions. The performance test results of each embodiment and comparative example are summarized in Tables 1, 2 and 3; Table 1. Mechanical property test results of each embodiment and comparative example.

[0059] Table 2. Test results of flame retardant and anti-aging properties of each embodiment and comparative example.

[0060] Table 3. Processing and application performance test results of each embodiment and comparative example.

[0061] As can be seen from the data in Tables 1-3, the modified high-elasticity straw nets prepared in Examples 1-3 of the present invention are significantly superior to the comparative examples in terms of mechanical properties, flame retardant properties, anti-aging properties and processing properties.

[0062] In terms of mechanical properties, the tensile strength of Examples 1-3 was 35.2-41.2 MPa, the elongation at break was 248-312%, and the right-angle tear strength was 79.3-91.5 kN / m. Comparative Example 1 had an elongation at break of only 22%, and the lowest tensile and tear strengths, indicating that the unmodified HDPE straw netting had poor elasticity and insufficient toughness. Comparative Example 2, which did not contain elastomer components, had an elongation at break of only 35%, far lower than the 248-312% of Examples 1-3, proving that the epoxy-functionalized ethylene-octene copolymer is the key component imparting high elasticity to the straw netting. Comparative Example 3, which did not contain maleic anhydride-grafted polyethylene coupling agent, had a tensile strength reduced to 25.5 MPa, significantly lower than Examples 1-3, indicating that the contribution of the "molecular bridge" interfacial coupling effect to mechanical strength is irreplaceable.

[0063] Regarding flame retardant performance, the limiting oxygen index (LOI) of Examples 1-3 ranged from 26.8% to 30.2%, all achieving the UL-94 V-0 rating. Comparative Examples 1 and 4, lacking flame retardants, had LOIs of 17.5% and 18.2%, respectively, failing to meet any UL-94 rating and thus classified as flammable materials. Comparative Examples 2 and 3, although containing flame retardants, suffered from poor dispersion and interfacial bonding due to the absence of elastomers and coupling agents, respectively, achieving only a UL-94 V-1 rating. This demonstrates the importance of multi-component synergistic design for flame retardant performance.

[0064] Regarding anti-aging properties, Examples 1-3 maintained a tensile strength retention rate of 90.5-93.8% and an elongation at break of 85.2-90.8% after 1000 hours of UV aging, and a tensile strength retention rate of 92.0-95.1% after 720 hours of heat aging. Comparative Example 5, lacking anti-aging components, exhibited a tensile strength retention rate of only 58.0% and an elongation at break retention rate of only 42.5% after UV aging, and a tensile strength retention rate of only 65.5% after heat aging, significantly lower than Examples 1-3. This demonstrates that the synergistic system of the primary antioxidant, secondary antioxidant, and light stabilizer is crucial for the long-term weather resistance of the straw netting. Comparative Example 1, lacking any anti-aging protection, also showed poor UV and heat aging performance.

[0065] Regarding processing performance, Examples 1-3 exhibited moderate melt flow rates (2.8-3.8 g / 10 min) and weaving efficiencies of 94-97%, making them suitable for continuous industrial production. Comparative Example 2, lacking elastomer components, had a lower melt flow rate (MFR) (2.0 g / 10 min) and a weaving efficiency of only 85%, resulting in poor processing performance. Comparative Example 5, lacking anti-aging components, was prone to thermal oxidative degradation during processing, resulting in a weaving efficiency of only 90%.

[0066] In summary, Examples 1-3 of this invention, through the multi-component synergistic design of high-density polyethylene matrix with epoxy-functionalized ethylene-octene copolymer, maleic anhydride-grafted polyethylene, organically modified wollastonite, composite flame retardant, and composite anti-aging components, achieve a comprehensive and balanced improvement in mechanical properties, flame retardant properties, anti-aging properties, and processing properties. This effectively solves the technical problem that traditional high-density polyethylene-based straw netting cannot simultaneously achieve elasticity, strength, flame retardancy, and weather resistance.

[0067] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0068] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modified, highly elastic straw net, characterized in that, It is composed of the following components: high-density polyethylene, epoxy-functionalized ethylene-octene copolymer, maleic anhydride-grafted polyethylene, organic modified wollastonite, composite flame retardant and composite anti-aging component; The epoxy-functionalized ethylene-octene copolymer is prepared by grafting glycidyl methacrylate onto an ethylene-octene copolymer. The maleic anhydride-grafted polyethylene is prepared by grafting maleic anhydride onto low-density polyethylene. The organically modified wollastonite is prepared by modifying wollastonite powder with phthalate coupling agent; The composite flame retardant is prepared by mixing triphenyl phosphate, melamine polyphosphate, pentaerythritol and organically modified montmorillonite. The composite anti-aging component is prepared by mixing a main antioxidant, a secondary antioxidant, and a light stabilizer.

2. The modified high-elasticity straw net according to claim 1, characterized in that, The grafting rate of the epoxy-functionalized ethylene-octene copolymer is 2-3%.

3. The modified high-elasticity straw net according to claim 1, characterized in that, The grafting rate of the maleic anhydride-grafted polyethylene is 1-2%.

4. The modified high-elasticity straw net according to claim 1, characterized in that, The method for preparing the organically modified wollastonite is as follows: Place wollastonite powder in a high-speed mixer, add 2-3% by weight of titanate coupling agent, and stir at 110-130℃ for 15-25 minutes to obtain organic modified wollastonite.

5. The modified high-elasticity straw net according to claim 1, characterized in that, The preparation method of the organically modified montmorillonite is as follows: Adjust the pH of 100 parts by weight of a 90% ethanol aqueous solution to 3-4, add 4-9 parts by weight of silane coupling agent KH-560, stir and hydrolyze for 4 hours, then add 10 parts by weight of montmorillonite, and then heat under reflux at 70-90℃ for 24 hours. After cooling to room temperature, filter and wash 3-5 times with anhydrous ethanol. After drying, place in a supercritical CO2 reactor at 40-80℃ and 20MPa for 2 hours. Finally, wash with deionized water and anhydrous ethanol in sequence and dry for 24 hours. The result is organically modified montmorillonite.

6. The modified high-elasticity straw net according to claim 1, characterized in that, The composite flame retardant is prepared by mixing triphenyl phosphate, melamine polyphosphate, pentaerythritol and organically modified montmorillonite in a weight ratio of (5-10):(3-5):(2-4):(1-2).

7. The modified high-elasticity straw net according to claim 1, characterized in that, The primary antioxidant is antioxidant 1010, the secondary antioxidant is antioxidant 168, and the light stabilizer is light stabilizer 944. The composite anti-aging component is prepared by mixing antioxidant 1010, antioxidant 168 and light stabilizer 944 in a weight ratio of 1:2:(3-5).

8. The preparation process of a modified high-elasticity straw net according to any one of claims 1-7, characterized in that, The preparation process includes the following steps: S1. Weigh 100 parts by weight of high-density polyethylene, 30-40 parts by weight of epoxy-functionalized ethylene-octene copolymer, 10-15 parts by weight of maleic anhydride-grafted polyethylene, 15-25 parts by weight of organic modified wollastonite, 20-30 parts by weight of composite flame retardant and 0.6-1.2 parts by weight of composite anti-aging component and pour them into a high-speed mixer for premixing. The result is called premix. S2. The premixed material is added to a twin-screw extruder for melt blending. After extrusion, it is water-cooled, drawn into strands, granulated, and dried. The resulting material is called premixed material granules. S3. Add the premixed granules into a single-screw extruder, and after extrusion and stretching into a film and splitting into filaments, obtain film filament yarn; S4. After the membrane yarn is hot-stretched and shaped, it is woven and finally annealed to obtain the modified high-elasticity straw net.

9. The preparation process of a modified high-elasticity straw net according to claim 8, characterized in that, The extrusion stretching film formation and fiber splitting method in S3 is as follows: The extrusion temperature is set to 180-200℃. The film is cast through a T-die and the film thickness is controlled at 0.08-0.12mm. After being cooled by a cooling roller at 25℃, the cast film enters the slitting device and is slitted into film yarns with a width of 1.5-2.5mm by a blade.

10. The preparation process of a modified high-elasticity straw net according to claim 8, characterized in that, The annealing heat treatment method in S4 is as follows: anneal at 90℃ for 20 minutes, and then naturally cool to room temperature.

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