A weather-resistant rubber material for pet strollers and its preparation method

Abstract

This invention belongs to the field of polymer materials technology, specifically relating to a weather-resistant rubber material for pet strollers and its preparation method. Addressing the current technical problems of poor compatibility and insufficient long-term effectiveness of multifunctional additive components with the matrix material, this invention employs a four-layer co-extrusion structure, including a base layer, a functional layer, a buffer layer, and a surface layer. The base layer is primarily composed of high-density polyethylene and contains elastic toughening components; the functional layer contains a thermoplastic elastomer matrix and nano-silica filler pretreated with a silane coupling agent; the buffer layer uses an aliphatic thermoplastic polyurethane elastomer; and the surface layer uses a thermoplastic elastomer matrix with added liquid rubber-coated multifunctional additive composite powder.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a weather-resistant rubber material for pet strollers and its preparation method. Background Technology

[0002] When pet strollers are used outdoors, their tires, handles, and canopies need to withstand long-term exposure to sunlight, rain, friction, abrasion, and microbial erosion. Therefore, strict requirements are placed on the weather resistance of the materials, including resistance to UV aging, prevention of material cracking, good waterproofing and mildew resistance, and wear-resistant and shock-absorbing properties.

[0003] However, traditional rubber or plastic materials often cannot simultaneously meet the aforementioned multiple performance requirements, necessitating the addition of multifunctional additives such as UV stabilizers, antibacterial agents, and friction-reducing and wear-resistant fillers to the matrix formulation to improve material performance (CN121226866A). However, directly adding additives to the polymer matrix presents several problems: firstly, different additives have varying particle sizes and surface polarities, resulting in poor compatibility with the matrix rubber or plastic, easily leading to uneven dispersion, agglomeration, or migration and precipitation, causing a decline in material mechanical properties and a reduction in the additive's effectiveness; secondly, additives may gradually be lost or deactivated during use, making it difficult to guarantee long-term efficacy. Furthermore, polytetrafluoroethylene (PTFE) micropowder is commonly used as a filler to reduce friction and wear, but because PTFE is extremely inert and lacks interfacial interaction with most polymers, direct addition often results in poor dispersion, failing to fully exert its lubricating and wear-resistant effects.

[0004] To address the aforementioned issues, several technical approaches have been proposed. For example, coating inorganic additives with a layer of polymeric modifier can improve their dispersibility and compatibility in the rubber matrix, and enhance the interfacial bonding between the additives and the matrix. Another effective method is to incorporate liquid rubber as a compatibilizer into the rubber formulation. Furthermore, in product structural design, multi-layer co-extrusion composite technology can combine materials with different functions, thereby simultaneously meeting multiple performance requirements.

[0005] In summary, existing technologies still have significant room for improvement in terms of the compatibility between functional additives and matrix materials, as well as the duration of their effects. There is an urgent need for a novel material structure and preparation method to significantly enhance the overall performance and durability of pet stroller materials. Summary of the Invention

[0006] This invention provides a weather-resistant rubber material for pet strollers and its preparation method, aiming to solve the problems of poor compatibility and short duration of action between functional additives and matrix materials.

[0007] The specific technical solution is as follows:

[0008] A weather-resistant rubber material for pet strollers and its preparation method are as follows:

[0009] S1: Preparation of bifunctional liquid rubber: Isoprene, 2-vinylpyridine, and glycidyl methacrylate were purified separately and then added sequentially to toluene solvent. Citrate dithiobenzoate and azobisisobutyronitrile were then added, stirred, frozen, vacuumed, and thawed. High-purity nitrogen was introduced, and the mixture was preheated to 65-70°C. After the reaction was completed, the mixture was cooled in an ice-water bath, and methanol was added dropwise to precipitate the mixture. The precipitate was then filtered, washed, and dried to obtain bifunctional liquid rubber.

[0010] S2: In-situ anchoring modification.

[0011] S21: Add the bifunctional liquid rubber prepared in S1 to toluene and stir to obtain a liquid rubber solution with a mass fraction of 10%.

[0012] S22: Polytetrafluoroethylene micro powder etched with tetrahydrofuran, silver-loaded zinc zeolite and UV stabilizer are added to the liquid rubber solution prepared in S21, stirred, ultrasonically dispersed, rotary evaporated, dried and ground to obtain functional additive composite powder.

[0013] S3: Mixing and extrusion.

[0014] S31: Dry high-density polyethylene (HDPE) and polyolefin elastomer (POE) toughening agent are melt-blended to obtain base layer composite granules.

[0015] S32: Thermoplastic elastomer (TPE) and nano-SiO2 modified with silane coupling agent are premixed and then melt-blended to obtain functional layer granules.

[0016] S33: Melt pure aliphatic thermoplastic polyurethane elastomer (TPU) to obtain buffer layer granules.

[0017] S34: The functional additive composite powder prepared by TPE and S22 is melt-blended to obtain surface layer granules.

[0018] S35: Adjust the extrusion speed of each extruder, obtain a co-extruded melt through co-extrusion, cool and shape it, and then irradiate it with electrons to obtain a weather-resistant rubber material.

[0019] Furthermore, the 2-vinylpyridine described in S1 has a molar ratio of 0.05:1 to 0.15:1 with the isoprene monomer.

[0020] The glycidyl methacrylate described in S1 has a molar ratio of 0.05:1 to 0.15:1 with the isoprene monomer.

[0021] The dithiobenzoic acid cumyl ester described in S1 has a molar ratio of 1:1 with the isoprene monomer.

[0022] The azobisisobutyronitrile described in S1 has a molar ratio of 0.1:1 to 0.2:1 with cumyl dithiobenzoate.

[0023] The freezing-vacuuming-thawing process described in S1 is repeated 3 times. The freezing is performed using liquid nitrogen, and the vacuum is drawn to 5 Pa and held for 5 minutes. The thawing is performed by thawing in warm water to room temperature.

[0024] The drying process described in S1 has the following parameters: temperature 40℃, duration 24h.

[0025] Furthermore, the ultrasonic dispersion described in S22 has the following parameter settings: power 300-500W, frequency 20-40kHz, and duration 30-40min.

[0026] The rotary evaporator described in S22 has the following parameter settings: temperature 60℃, vacuum degree -0.08~-0.1MPa, and rotation speed 60~100rpm.

[0027] The functional additive composite powder described in S22 has the following composition of raw materials: based on 100 parts of bifunctional liquid rubber, 300-500 parts of polytetrafluoroethylene micro powder etched with tetrahydrofuran, 150-200 parts of silver-loaded zinc zeolite, and 20-25 parts of UV stabilizer.

[0028] Furthermore, the melt blending described in S31 has the following parameter settings: feeding section temperature 160-170℃, compression section temperature 170-180℃, metering section temperature 180-190℃, and screw speed 20-60 rpm.

[0029] The basic layer composite granules described in S31 have the following raw material weight ratio: 70% to 90% high-density polyethylene and 10% to 30% maleic anhydride-grafted POE toughening agent.

[0030] The melt blending described in S32 has the following parameter settings: feeding section temperature 170-180℃, compression section temperature 180-190℃, metering section temperature 190-200℃, and screw speed 20-60 rpm.

[0031] The functional layer granules described in S32 have the following raw material ratio: based on 100 parts of TPE, the amount of nano-SiO2 modified with silane coupling agent is 3 to 8 parts.

[0032] The melting process described in S33 has the following parameter settings: feeding section temperature 170-180℃, compression section temperature 180-190℃, metering section temperature 190-200℃, and screw speed 20-60 rpm.

[0033] The melt blending described in S34 has the following parameter settings: feeding section temperature 170-180℃, compression section temperature 180-190℃, metering section temperature 190-200℃, and screw speed 20-60 rpm.

[0034] The surface layer granules described in S34 have the following raw material ratio: based on 100 parts of TPE, the functional additive composite powder is 10 to 15 parts.

[0035] The co-extrusion described in S35 has the following parameter settings: temperature 190~200℃, extrusion pressure 8~15MPa.

[0036] The cooling and shaping described in S35 has the following parameter settings: the temperature of the first cooling roller is 40-60℃, and the temperature of the second cooling roller is 20-30℃.

[0037] The electron irradiation described in S35 has the following parameter settings: irradiation dose 70 kGy, accelerating voltage 2 MeV, and beam current 30 mA.

[0038] The weather-resistant rubber material described in S35 has the following thickness ratio for each layer: base layer: functional layer: buffer layer: surface layer (8-12): (3-5): 1: (1-2).

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. This invention improves the uniformity of dispersion and interfacial bonding of additives in the matrix by encapsulating the additives with bifunctional liquid rubber.

[0041] 2. This invention utilizes a multi-layer structure design, with a base layer of HDPE providing rigid support, a buffer layer of TPU providing flexibility and impact resistance, and a surface layer of TPE that balances elasticity and wear resistance, achieving a balance between high strength, high resilience, and tear resistance. Attached Figure Description

[0042] Figure 1 This is a process flow diagram for the preparation of a weather-resistant rubber material used in pet strollers.

[0043] Figure 2 This is the FTIR image of the liquid rubber solution prepared in S21 of Example 1.

[0044] Figure 3 These are FTIR images of the materials before and after the process treatment in S22 of Example 1. Detailed Implementation

[0045] The following embodiments further explain and illustrate the technical solutions of the present invention. It should be specifically noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention.

[0046] This invention proposes a weather-resistant rubber material for pet strollers and its preparation method. By combining the design of material components with the preparation process, the technical challenges of compatibility and long-lasting effect of multifunctional additives with the matrix are effectively solved. (See attached diagram) Figure 1 The image shows a method for preparing a weather-resistant rubber material for pet strollers, and its detailed technical solution is as follows:

[0047] 1. Preparation of bifunctional liquid rubber

[0048] Isoprene (IP), 2-vinylpyridine (2-VP), and glycidyl methacrylate (GMA) were purified separately and then added sequentially to toluene solvent. Cumex dithiobenzoate (RAFT reagent) and azobisisobutyronitrile (AIBN) were then added, stirred, frozen, vacuumed, and thawed. High-purity nitrogen was introduced, and the mixture was preheated to 65–70°C. After the reaction was complete, the mixture was cooled in an ice-water bath, and methanol was added dropwise to precipitate the precipitate. The precipitate was filtered, washed, and dried to obtain a bifunctional liquid rubber.

[0049] The reactivity ratios of GMA and IP are both less than 1, indicating that they tend to copolymerize alternately, which is conducive to the formation of random structures. The reactivity ratio of 2-VP with other monomers is greater than 1, indicating that it has a certain tendency to self-polymerize, but random copolymerization can still be achieved under controlled feed. AIBN decomposes to generate primary free radicals, which add to monomers to form growing free radicals. The growing free radicals continue to react with monomers, increasing the chain length. At the same time, the growing free radicals undergo addition reactions with RAFT reagents to form intermediate free radicals. The intermediate free radicals break, releasing new free radicals and dormant species. The new free radicals can restart polymerization to form new growing free radicals. Reversible addition-breakage continuously occurs between growing free radicals and dormant species, giving all chains an equal opportunity to grow, thus achieving a narrow distribution. Furthermore, under the RAFT polymerization conditions of 65-70℃, free radicals cannot attack epoxy groups, so the epoxy groups in GMA can be completely preserved; the pyridinium group in 2-vinylpyridine contains a nitrogen atom and has a lone pair of electrons. In free radical polymerization, the pyridine group does not participate in the free radical reaction, and the lone pair electrons of the nitrogen atom do not interact with the free radical. Therefore, the pyridine group is also preserved intact.

[0050] 2. In-situ anchoring modification

[0051] Bifunctional liquid rubber was added to toluene and stirred to obtain a liquid rubber solution. Polytetrafluoroethylene micro powder etched with tetrahydrofuran, silver-loaded zinc zeolite and UV stabilizer were added to the liquid rubber solution, stirred, ultrasonically dispersed, rotary evaporated, dried and ground to obtain a functional additive composite powder.

[0052] The bifunctionalized liquid rubber has a low molecular weight and exhibits good flowability and wettability in toluene solution. When the functional additive powder is added, the liquid rubber molecular chains can fully unfold and adsorb onto the powder particle surface, forming a physical coating layer. This reduces the surface energy of the powder, prevents re-agglomeration, and simultaneously forms a "core-shell" structure, with the functional additive as the core and the liquid rubber as the shell, improving the compatibility of the powder with the subsequent TPE matrix. The nitrogen atom in the pyridinium group of 2-vinylpyridine possesses a lone pair of electrons, enabling it to coordinate with metal ions on the surface of silver-zinc zeolite, forming a stable complex. This coordination firmly anchors the liquid rubber to the zeolite surface, making it difficult to desorb. The epoxy group introduced by glycidyl methacrylate has high reactivity, undergoing a ring-opening reaction with the hydroxyl groups on the surface of the functional additive to form a covalent bond. Ultimately, the three functional additives achieve a synergistic effect.

[0053] 3. Mixing and extrusion

[0054] Dry high-density polyethylene and maleic anhydride-grafted POE toughening agent are melt-blended to obtain base layer composite granules; TPE and silane coupling agent-modified nano-SiO2 are pre-mixed and then melt-blended to obtain functional layer granules; pure TPU is melt-blended to obtain buffer layer granules; TPE and functional additive composite powder are melt-blended to obtain surface layer granules; the extrusion speed of each extruder is adjusted, and co-extrusion is carried out to obtain a co-extruded melt, which is then cooled and shaped, and electron irradiated to obtain a weather-resistant rubber material.

[0055] High-density polyethylene (HDPE) has regular molecular chains and high crystallinity, providing excellent rigidity and strength. POE, an ethylene-octene copolymer, possesses rubber elasticity and is uniformly dispersed in the HDPE matrix. Under external force, it induces crazing and absorbs impact energy, achieving a toughening effect. Nano-silica has a high specific surface area and surface activity. After treatment with a silane coupling agent, organic functional groups are grafted onto the surface, forming a good interfacial bond with the TPE matrix. The nanoparticles form a three-dimensional network structure in the matrix, improving modulus and strength, while extending the gas and liquid permeation path and absorbing and scattering ultraviolet rays. TPU molecular chains consist of soft and hard segments, forming a microphase-separated structure. The soft segments provide elasticity and flexibility, while the hard segments form physical cross-linking points, providing strength and heat resistance. The surface layer imparts a low coefficient of friction through PTFE micropowder, achieving self-cleaning and wear resistance; silver-zinc zeolite provides antibacterial properties; and an anti-UV agent absorbs harmful ultraviolet rays, delaying material aging. Electron beam irradiation crosslinking generates free radicals on the molecular chains. These free radicals combine to form crosslinking bonds, thereby transforming the linear molecular structure into a three-dimensional network structure. This further "locks" the functional additive composite powder within the crosslinking network, preventing migration during long-term use and improving interlayer bonding strength to prevent delamination.

[0056] Example 1

[0057] A method for preparing a weather-resistant rubber material for pet strollers is as follows:

[0058] Table 1 Main Raw Materials

[0059]

[0060] S1: Preparation of bifunctional liquid rubber: Isoprene, 2-vinylpyridine, and glycidyl methacrylate were purified separately and then added sequentially to toluene solvent. Citrate dithiobenzoate and azobisisobutyronitrile were then added, stirred, frozen, vacuumed, and thawed. High-purity nitrogen was introduced, and the mixture was preheated to 68°C. After the reaction was completed, the mixture was cooled in an ice-water bath, and methanol was added dropwise to precipitate the mixture. The mixture was then filtered, washed, and dried to obtain bifunctional liquid rubber. The molar ratio of 2-vinylpyridine to isoprene monomer was 0.1:1; the molar ratio of glycidyl methacrylate to isoprene monomer was 0.1:1; the molar ratio of cumyl dithiobenzoate to isoprene monomer was 1:1; and the molar ratio of azobisisobutyronitrile to cumyl dithiobenzoate was 0.15:1. The freezing-vacuuming-thawing process was repeated three times. Freezing was performed using liquid nitrogen, and the vacuum was drawn to 5 Pa and held for 5 min. Thawing was performed using warm water to room temperature. The drying parameters were set as follows: temperature 40℃, duration 24 h.

[0061] S2: In-situ anchoring modification.

[0062] S21: Add the bifunctional liquid rubber prepared in S1 to toluene and stir to obtain a liquid rubber solution with a mass fraction of 10%.

[0063] S22: 400g of polytetrafluoroethylene micropowder etched with tetrahydrofuran, 175g of silver-zinc zeolite, and 23g of UV stabilizer were added to 100g of the liquid rubber solution prepared in S21. The mixture was stirred, ultrasonically dispersed, rotary evaporated, dried, and ground to obtain a functional additive composite powder. The ultrasonic dispersion parameters were set as follows: power 400W, frequency 30kHz, duration 35min. The rotary evaporation parameters were set as follows: temperature 60℃, vacuum degree -0.09MPa, rotation speed 80rpm.

[0064] S3: Mixing and extrusion.

[0065] S31: The dried high-density polyethylene and maleic anhydride-grafted POE toughening agent are melt-blended to obtain the base layer composite granules. The melt-blending parameters are set as follows: feeding section temperature 165℃, compression section temperature 175℃, metering section temperature 185℃, and screw speed 40 rpm. The raw material composition of the base layer composite granules is as follows: high-density polyethylene 80%, maleic anhydride-grafted POE toughening agent 20%.

[0066] S32: TPE and silane coupling agent-modified nano-SiO2 are premixed and then melt-blended to obtain functional layer granules. The melt-blending parameters are set as follows: feeding section temperature 175℃, compression section temperature 185℃, metering section temperature 195℃, and screw speed 40rpm. The raw material ratio for the functional layer granules is as follows: based on 100 parts TPE, 5.5 parts of silane coupling agent-modified nano-SiO2.

[0067] S33: Melt aliphatic TPU to obtain buffer layer granules. The melting parameters are set as follows: feeding section temperature 175℃, compression section temperature 185℃, metering section temperature 195℃, and screw speed 40rpm.

[0068] S34: The TPE and the functional additive composite powder prepared in S22 are melt-blended to obtain surface layer granules. The melt-blending parameters are set as follows: feeding section temperature 175℃, compression section temperature 185℃, metering section temperature 195℃, and screw speed 40 rpm. The raw material ratio for the surface layer granules is as follows: based on 100 parts TPE, the functional additive composite powder is 12.5 parts.

[0069] S35: Adjust the extrusion speed of each extruder to obtain a co-extruded melt through co-extrusion, followed by cooling and shaping, and electron irradiation to obtain a weather-resistant rubber material (base layer: functional layer: buffer layer: surface layer ratio of 10:4:1:1.5). Co-extrusion parameters are set as follows: temperature 195℃, extrusion pressure 12MPa; cooling and shaping parameters are set as follows: first cooling roller temperature 50℃, second cooling roller temperature 25℃; electron irradiation parameters are set as follows: irradiation dose 70kGy, accelerating voltage 2MeV, beam current 30mA.

[0070] Example 2

[0071] The composition and preparation process are the same as in Example 1, except that:

[0072] In step S1 of the preparation process, the temperature is raised to 65°C, and the other steps are the same.

[0073] In process S1, the molar ratio of 2-vinylpyridine to isoprene monomer is 0.05:1; the molar ratio of glycidyl methacrylate to isoprene monomer is 0.05:1; the molar ratio of azobisisobutyronitrile to cumyl dithiobenzoate is 0.1:1, and other components are the same.

[0074] In step S22 of the preparation process, the ultrasonic dispersion parameters were set as follows: power 300W, frequency 20kHz, duration 30min. The rotary evaporation parameters were set as follows: temperature 60℃, vacuum degree -0.08MPa, rotation speed 60rpm. Other steps were the same.

[0075] The functional additive composite powder in the S22 preparation process has the following raw material composition ratio: based on 100 parts of bifunctional liquid rubber, 300 parts of polytetrafluoroethylene micro powder etched with tetrahydrofuran, 150 parts of silver-loaded zinc zeolite, 20 parts of UV stabilizer, and other components are the same.

[0076] The raw material composition of the basic layer composite granules in the S31 preparation process is as follows: 70% high-density polyethylene, 30% maleic anhydride-grafted POE toughening agent, and the other components are the same.

[0077] The melt blending parameters in step S31 of the preparation process are set as follows: feeding section temperature 160℃, compression section temperature 170℃, metering section temperature 180℃, screw speed 20rpm, and other steps are the same.

[0078] The melt blending parameters in S32 of the preparation process are set as follows: feeding section temperature 170℃, compression section temperature 180℃, metering section temperature 190℃, screw speed 20rpm, and other steps are the same.

[0079] The proportions of the functional layer granule raw materials in the S32 preparation process are as follows: based on 100 parts TPE, 3 parts of nano-SiO2 modified with silane coupling agent, and the other components are the same.

[0080] The melt blending parameters in S33 of the preparation process are set as follows: feeding section temperature 170℃, compression section temperature 180℃, metering section temperature 190℃, screw speed 20rpm, and other steps are the same.

[0081] The melt blending parameters in step S34 of the preparation process are set as follows: feeding section temperature 170℃, compression section temperature 180℃, metering section temperature 190℃, screw speed 20rpm, and other steps are the same.

[0082] The formulation of surface layer granular raw materials in S34 of the preparation process is as follows: based on 100 parts of TPE, 10 parts of functional additive composite powder, and other components are the same.

[0083] The S35 co-extrusion parameters for the preparation process are set as follows: temperature 190℃, extrusion pressure 8MPa, and cooling and shaping parameters: first cooling roller temperature 40℃, second cooling roller temperature 20℃. Other steps are the same.

[0084] The weather-resistant rubber material in the S35 preparation process has the following thickness ratio for each layer: base layer: functional layer: buffer layer: surface layer is 8:3:1:1, and other components are the same.

[0085] Example 3

[0086] The composition and preparation process are the same as in Example 1, except that:

[0087] In step S1 of the preparation process, the temperature is raised to 70°C, and the other steps are the same.

[0088] In process S1, the molar ratio of 2-vinylpyridine to isoprene monomer is 0.15:1; the molar ratio of glycidyl methacrylate to isoprene monomer is 0.15:1; the molar ratio of azobisisobutyronitrile to cumyl dithiobenzoate is 0.2:1, and other components are the same.

[0089] In step S22 of the preparation process, the ultrasonic dispersion parameters were set as follows: power 500W, frequency 40kHz, duration 40min. The rotary evaporation parameters were set as follows: temperature 60℃, vacuum degree -0.1MPa, rotation speed 100rpm. Other steps were the same.

[0090] The functional additive composite powder in the S22 preparation process has the following composition of each raw material: based on 100 parts of bifunctional liquid rubber, 500 parts of polytetrafluoroethylene micro powder etched with tetrahydrofuran, 200 parts of silver-loaded zinc zeolite, 25 parts of UV stabilizer, and other components are the same.

[0091] The raw material composition of the basic layer composite granules in the S31 preparation process is as follows: 90% high-density polyethylene, 10% maleic anhydride-grafted POE toughening agent, and the other components are the same.

[0092] The melt blending parameters in step S31 of the preparation process are set as follows: feeding section temperature 170℃, compression section temperature 180℃, metering section temperature 190℃, screw speed 60rpm, and other steps are the same.

[0093] The melt blending parameters in S32 of the preparation process are set as follows: feeding section temperature 180℃, compression section temperature 190℃, metering section temperature 200℃, screw speed 60rpm, and other steps are the same.

[0094] The raw material composition of the functional layer granules in the S32 preparation process is as follows: based on 100 parts of TPE, 8 parts of nano-SiO2 modified with silane coupling agent, and the other components are the same.

[0095] The melt blending parameters in process S33 are set as follows: feeding section temperature 180℃, compression section temperature 190℃, metering section temperature 200℃, screw speed 60rpm, and other steps are the same.

[0096] The melt blending parameters in step S34 of the preparation process are set as follows: feeding section temperature 180℃, compression section temperature 190℃, metering section temperature 200℃, screw speed 60rpm, and other steps are the same.

[0097] The formulation of surface layer granules in S34 of the preparation process is as follows: based on 100 parts of TPE, the functional additive composite powder is 15 parts, and the other components are the same.

[0098] The S35 co-extrusion parameters for the preparation process are set as follows: temperature 200℃, extrusion pressure 15MPa, and cooling and shaping parameters: first cooling roller temperature 60℃, second cooling roller temperature 30℃. Other steps are the same.

[0099] The weather-resistant rubber material in the S35 preparation process has the following thickness ratio for each layer: base layer: functional layer: buffer layer: surface layer is 12:5:1:2, and other components are the same.

[0100] Example 4

[0101] The composition and preparation process are the same as in Example 1, except that:

[0102] In step S1 of the preparation process, the temperature is raised to 66°C, and the other steps are the same.

[0103] In process S1, the molar ratio of 2-vinylpyridine to isoprene monomer is 0.08:1; the molar ratio of glycidyl methacrylate to isoprene monomer is 0.12:1; the molar ratio of azobisisobutyronitrile to cumyl dithiobenzoate is 0.17:1, and other components are the same.

[0104] In step S22 of the preparation process, the ultrasonic dispersion parameters were set as follows: power 350W, frequency 25kHz, duration 37min. The rotary evaporation parameters were set as follows: temperature 60℃, vacuum degree -0.085MPa, rotation speed 90rpm. Other steps were the same.

[0105] The functional additive composite powder in the S22 preparation process has the following raw material composition ratio: based on 100 parts of bifunctional liquid rubber, 350 parts of polytetrafluoroethylene micro powder etched with tetrahydrofuran, 190 parts of silver-loaded zinc zeolite, 21 parts of UV stabilizer, and other components are the same.

[0106] The raw material composition of the basic layer composite granules in the S31 preparation process is as follows: 75% high-density polyethylene, 25% maleic anhydride-grafted POE toughening agent, and the other components are the same.

[0107] The melt blending parameters in S31 of the preparation process are set as follows: feeding section temperature 164℃, compression section temperature 172℃, metering section temperature 188℃, screw speed 55rpm, and other steps are the same.

[0108] The melt blending parameters in step S32 of the preparation process are set as follows: feeding section temperature 173℃, compression section temperature 184℃, metering section temperature 192℃, screw speed 25rpm, and other steps are the same.

[0109] The raw material composition of the functional layer granules in the S32 preparation process is as follows: based on 100 parts of TPE, 4 parts of nano-SiO2 modified with silane coupling agent, and the other components are the same.

[0110] The melt blending parameters in process S33 are set as follows: feeding section temperature 178℃, compression section temperature 188℃, metering section temperature 192℃, screw speed 35rpm, and other steps are the same.

[0111] The melt blending parameters in step S34 of the preparation process are set as follows: feeding section temperature 173℃, compression section temperature 181℃, metering section temperature 196℃, screw speed 50rpm, and other steps are the same.

[0112] The formulation of surface layer granular raw materials in S34 of the preparation process is as follows: based on 100 parts of TPE, the functional additive composite powder is 11 parts, and other components are the same.

[0113] The S35 co-extrusion parameters for the preparation process are set as follows: temperature 197℃, extrusion pressure 14MPa, and cooling and shaping parameters: first cooling roller temperature 55℃, second cooling roller temperature 28℃. Other steps are the same.

[0114] The weather-resistant rubber material in the S35 preparation process has the following thickness ratio for each layer: base layer: functional layer: buffer layer: surface layer is 9:3.5:1:1.5, and other components are the same.

[0115] Comparative Example 1

[0116] The composition and preparation process are the same as in Example 1, except that:

[0117] In step S1 of the preparation process, the preparation of bifunctional liquid rubber is removed. In step S2, the traditional physical blending method is adopted: PTFE micro powder, silver-loaded zinc zeolite, UV stabilizer and TPE are directly mixed and then used as surface layer material. The other steps are the same.

[0118] Comparative Example 2

[0119] The composition and preparation process are the same as in Example 1, except that:

[0120] In process S3, multi-layer co-extrusion is not used. All components are fed into a single screw extruder for blending at once, and the other steps are the same.

[0121] Samples of the liquid rubber solution prepared in S21 of Example 1 were taken and subjected to Fourier transform infrared spectroscopy. Potassium bromide was used as a carrier. The liquid rubber solution was coated onto the carrier and vacuum dried (50°C for 5 min). The results were then analyzed using an infrared spectrometer (scanning range 4000–500 cm⁻¹). -1 (64 scans) Figure 2 As shown, at 3000cm -1 Nearby, a distinct, sharp peak appears, indicating an aliphatic CH stretching vibration, at 1760 cm⁻¹. -1 Nearby, the vibrations are due to the stretching vibrations of the C=C double bonds in the skeleton, occurring between 1560 and 1600 cm⁻¹. -1 The C=N and C=C skeletal stretching vibrations of the pyridine ring in 2-vinylpyridine indicate the presence of the pyridine group, and the vibration occurs at 950 cm⁻¹. -1 Nearby, the asymmetric deformation vibration of the terminal epoxy ring in glycidyl methacrylate indicates that glycidyl methacrylate was successfully introduced and the epoxy groups were retained intact.

[0122] Samples of the materials taken before and after the process in S22 of Example 1 (before modification, a mixture of bifunctional liquid rubber and functional additives; after modification, a composite powder of functional additives after the reaction) were subjected to Fourier transform infrared spectroscopy (scanning range 4000–500 cm⁻¹) using an FTIR spectrometer with attenuated total reflectance (ATR) accessory. -1 (64 scans), the sample was placed over the central test area of ​​the ATR crystal (diamond crystal) and pressure was applied, such as... Figure 3 As shown, in the range of 3700–3750 cm-1 Near the modified PTFE surface, the intensity of the stretching vibration peak decreased, indicating that a large amount of undisturbed isolated -OH groups on the zeolite or etched PTFE surface were consumed, in the range of 3500–3650 cm⁻¹. -1 Near the modified area, the intensity of the absorption band decreased, indicating that the surface-aggregated hydroxyl groups participated in the reaction as nucleophiles and were converted into ether bonds, in the range of 1000–1200 cm⁻¹. -1 Near the site, the modified sample exhibits a broadening of the spectral band, indicating that extremely stable and irreversible CO-Si or COC bonds were formed after ring opening, leading to superposition of absorption in this region, particularly at 900 cm⁻¹. -1 Near the modified peak intensity, the decrease indicates that the epoxy ring has undergone a ring-opening reaction. At the same time, the disappearance rate of the epoxy peak directly reflects the conversion rate of chemical grafting.

[0123] Based on Examples 1-4 and Comparative Examples 1-2, samples of the finally prepared weather-resistant rubber material were taken for tensile strength testing: the material was prepared into dumbbell-shaped specimens (cut from the transverse and longitudinal directions respectively), and placed in an environment with a temperature of 23°C and a relative humidity of 50% for 48 hours. The width and thickness of three points on the parallel part of the specimen were measured, and the average value was taken. Then, a universal testing machine was used to perform a tensile test (500 mm / min, original gauge length 25 mm), and the maximum force value when the specimen broke was recorded. Ten sets of tests were performed, and the average value was taken.

[0124] Based on Examples 1-4 and Comparative Examples 1-2, samples of the finally prepared weather-resistant rubber material were taken for tensile strength retention tests: the material was prepared into dumbbell-shaped specimens (cut from the transverse and longitudinal directions respectively), placed in a hot air aging chamber for aging (temperature 70℃, duration 7d), and then placed in an environment with a temperature of 23℃ and a relative humidity of 50% for 24h. Subsequent test steps were the same as for the tensile strength test.

[0125] Based on Examples 1-4 and Comparative Examples 1-2, samples of the finally prepared weather-resistant rubber material were taken for antibacterial rate decay tests: The material was cut into 50mm×50mm pieces, and Gram-negative Escherichia coli was selected as the standard test strain. The sample was placed flat in a sterile petri dish, and the bacterial suspension was pipetted onto the sample surface. Immediately afterward, a sterile polyethylene film (40mm×40mm) was covered, and the bacterial suspension was evenly spread. The petri dish was then covered and incubated for 24 hours at 37℃ and relative humidity ≥90%. After incubation, the sample was eluted, and the eluent was serially diluted 10-fold. The diluted liquid was inoculated onto nutrient agar medium and incubated again at 37℃ for 24 hours. Viable bacteria were counted, and blank control samples (samples without antibacterial function) were tested using the same method to calculate the initial antibacterial rate. Another group of samples was placed in a hot air aging chamber for aging (temperature 70℃, duration 7 days). The above tests were repeated for 5 groups, and the average value was taken.

[0126] Combining Examples 1-4 and Comparative Examples 1-2, samples of the finally prepared weather-resistant rubber material were taken for UV resistance testing: the material was cut into 50mm × 50mm pieces, the sample surface was wiped with ethanol to remove dust, oil, and other contaminants, the sample was placed at the spectrophotometer measuring port, and measurements were taken at three different locations. The average value was taken as the initial yellow index, and the test was conducted using a UV aging test chamber with 8 hours of light irradiation (irradiance 0.8W / m²). 2 The sample was subjected to a 4-hour period of no light exposure (95% relative humidity) for 120 hours. After the cycle was completed, the sample was placed in an environment with a temperature of 23℃ and a relative humidity of 50% for 24 hours. The yellow index was then tested, and 5 sets of samples were measured and the average value was taken.

[0127] Based on Examples 1-4 and Comparative Examples 1-2, samples of the finally prepared weather-resistant rubber material were taken for peel strength testing: the material was cut into strips (50mm×15mm) from both the transverse and longitudinal directions, placed in an environment with a temperature of 23℃ and a relative humidity of 50% for 36h, and then tested using a universal testing machine (100mm / min). Five groups of tests were performed, and the average value was taken.

[0128] The specific test results are shown in Table 2. Figure 2 , Figure 3 As shown:

[0129] Table 2 Comparison of core performance of Examples 1-4 and Comparative Examples 1-2

[0130]

[0131] The above comparison results show that Example 1 has the best overall performance. The preparation of the bifunctional liquid rubber and the balance of the process indicate that Example 1 successfully solved the compatibility and long-term effects of the multifunctional components and the matrix. The overall performance of Examples 2 to 4 is slightly lower than that of Example 1, but still maintains a high level. This shows that excellent compatibility and long-term effects were still achieved under a large range of parameter variations. Comparative Example 1, because it removed the bifunctional liquid rubber and directly used traditional physical blending, formed stress concentration points due to the large polarity difference between the functional additives and the TPE matrix. Therefore, the interfacial bonding strength and mechanical properties were poor. Due to the lack of anchoring effect, the functional additives were prone to migration and loss during aging, resulting in poor long-term effects. Comparative Example 2 did not use multi-layer co-extrusion. All components were put into a single screw extruder for blending at one time, which led to serious compatibility problems. At the same time, the structural and functional distinctions of the functional layer, buffer layer and base layer were completely lost, resulting in the worst long-term effects.

[0132] In summary, it is clear from the above embodiments and comparative examples that the weather-resistant rubber material provided by the present invention is significantly superior to traditional solutions in terms of tensile strength and long-term efficiency. This is attributed to the preparation of bifunctional liquid rubber, in-situ anchoring modification, and multilayer co-extrusion process, which solves the problems of compatibility and long-term performance between the multifunctional components and the matrix.

Claims

1. A weather-resistant rubber material for pet strollers, characterized in that: The rubber material has a four-layer co-extruded composite structure, comprising, from bottom to top: a base layer, a functional layer, a buffer layer, and a surface layer. The base layer is composed of high-density polyethylene and a polyolefin elastomer toughening agent. The functional layer is composed of a thermoplastic elastomer and nano-silica filler pretreated with a silane coupling agent. The buffer layer is an aliphatic thermoplastic polyurethane elastomer. The surface layer is composed of a thermoplastic elastomer matrix containing a functional additive composite powder. The functional additive composite powder is coated with bifunctional liquid rubber, and the composition of its raw materials is as follows: 100 parts bifunctional liquid rubber... Based on the above, 300-500 parts of polytetrafluoroethylene micro powder etched with tetrahydrofuran, 150-200 parts of silver-zinc zeolite, and 20-25 parts of UV stabilizer were used. The bifunctional liquid rubber was prepared by refining isoprene, 2-vinylpyridine, and glycidyl methacrylate separately, then adding them sequentially to toluene solvent, followed by the addition of cumyl dithiobenzoate and azobisisobutyronitrile, stirring, freezing-vacuuming-thawing, purging with high-purity nitrogen, preheating to 65-70°C, cooling in an ice-water bath after the reaction was completed, adding methanol dropwise to precipitate the precipitate, filtering, washing, and drying.

2. The weather-resistant rubber material for pet strollers according to claim 1, characterized in that: The base layer has the following raw material composition: 70%–90% high-density polyethylene and 10%–30% polyolefin elastomer toughening agent.

3. The weather-resistant rubber material for pet strollers according to claim 1, characterized in that: The functional layer has the following raw material composition: based on 100 parts of thermoplastic elastomer, the amount of nano-SiO2 modified with silane coupling agent is 3 to 8 parts.

4. The weather-resistant rubber material for pet strollers according to claim 1, characterized in that: The thickness ratio of each layer of the weather-resistant rubber material is as follows: base layer: functional layer: buffer layer: surface layer is (8-12):(3-5):1:(1-2).

5. A method for preparing a weather-resistant rubber material for pet strollers according to any one of claims 1-4, characterized in that, Includes the following steps: S1: Preparation of bifunctional liquid rubber: Isoprene, 2-vinylpyridine, and glycidyl methacrylate were purified separately and then added sequentially to toluene solvent. Citrate dithiobenzoate and azobisisobutyronitrile were then added, stirred, frozen, vacuumed, and thawed. High-purity nitrogen was introduced, and the mixture was preheated to 65-70°C. After the reaction was completed, the mixture was cooled in an ice-water bath, and methanol was added dropwise to precipitate the mixture. The precipitate was filtered, washed, and dried to obtain bifunctional liquid rubber. S2: In-situ anchoring modification; S21: Add the bifunctional liquid rubber prepared in S1 to toluene and stir to obtain a liquid rubber solution with a mass fraction of 10%. S22: Polytetrafluoroethylene micro powder etched with tetrahydrofuran, silver-loaded zinc zeolite and UV stabilizer are added to the liquid rubber solution prepared in S21, stirred, ultrasonically dispersed, rotary evaporated, dried and ground to obtain functional additive composite powder. S3: Mixing and extrusion; S31: Dry high-density polyethylene and maleic anhydride-grafted POE toughening agent are melt-blended to obtain the base layer composite granules. S32: Premix thermoplastic elastomer and silane coupling agent modified nano-SiO2, and then melt blend to obtain functional layer granules; S33: Melt pure aliphatic thermoplastic polyurethane elastomer to obtain buffer layer granules; S34: The thermoplastic elastomer and the functional additive composite powder prepared in S22 are melt-blended to obtain surface layer granules; S35: Adjust the extrusion speed of each extruder, obtain a co-extruded melt through co-extrusion, cool and shape it, and then irradiate it with electrons to obtain a weather-resistant rubber material.

6. The method for preparing a weather-resistant rubber material for a pet stroller according to claim 5, characterized in that: The 2-vinylpyridine described in S1 has a molar ratio of 0.05:1 to 0.15:1 with the isoprene monomer. The glycidyl methacrylate described in S1 has a molar ratio of 0.05:1 to 0.15:1 with the isoprene monomer. The dithiobenzoic acid cumyl ester described in S1 has a molar ratio of 1:1 with the isoprene monomer. The azobisisobutyronitrile described in S1 has a molar ratio of 0.1:1 to 0.2:1 with cumyl dithiobenzoate. The freezing-vacuuming-thawing process described in S1 is repeated 3 times. Freezing is done with liquid nitrogen, and the vacuum is drawn to 5 Pa and held for 5 min. Thawing is done with warm water to room temperature. The drying process described in S1 has the following parameters: temperature 40℃, duration 24h.

7. The method for preparing a weather-resistant rubber material for a pet stroller according to claim 5, characterized in that: The ultrasonic dispersion described in S22 has the following parameter settings: power 300-500W, frequency 20-40kHz, and duration 30-40min; The rotary evaporator described in S22 has the following parameter settings: temperature 60℃, vacuum degree -0.08~-0.1MPa, and rotation speed 60~100rpm.

8. A method for preparing a weather-resistant rubber material for a pet stroller according to claim 5, characterized in that: The melt blending described in S31 has the following parameter settings: feeding section temperature 160-170℃, compression section temperature 170-180℃, metering section temperature 180-190℃, and screw speed 20-60 rpm. The melt blending described in S32 has the following parameter settings: feeding section temperature 170-180℃, compression section temperature 180-190℃, metering section temperature 190-200℃, and screw speed 20-60 rpm. The melting process described in S33 has the following parameter settings: feeding section temperature 170-180℃, compression section temperature 180-190℃, metering section temperature 190-200℃, and screw speed 20-60 rpm. The melt blending described in S34 has the following parameter settings: feeding section temperature 170-180℃, compression section temperature 180-190℃, metering section temperature 190-200℃, and screw speed 20-60 rpm. The surface layer granules described in S34 have the following raw material ratio: based on 100 parts of thermoplastic elastomer, the functional additive composite powder is 10 to 15 parts.

9. A method for preparing a weather-resistant rubber material for a pet stroller according to claim 5, characterized in that: The co-extrusion described in S35 has the following parameter settings: temperature 190~200℃, extrusion pressure 8~15MPa; The cooling and shaping described in S35 has the following parameter settings: the temperature of the first cooling roller is 40-60℃, and the temperature of the second cooling roller is 20-30℃. The electron irradiation described in S35 has the following parameter settings: irradiation dose 70 kGy, accelerating voltage 2 MeV, and beam current 30 mA.

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