Novel nylon modified material, high-strength excavator oil cylinder guide ring and preparation process of high-strength excavator oil cylinder guide ring

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a novel nylon modified material, a high-strength excavator oil cylinder guide ring and a preparation process of the high-strength excavator oil cylinder guide ring. According to the material, high-temperature nylon is used as a matrix, two modified compounds of a bicyclic guanidine zinc metal organic framework and hyperbranched phosphorus-containing polyester are innovatively introduced, and alkali-free chopped glass fibers, boron nitride, an antioxidant and an ultraviolet light absorber are cooperated. The bicyclic guanidine zinc metal organic framework is prepared by regulating the pH value of aminoguanidine salt, furandicarboxylic acid and zinc nitrate according to a specific molar ratio in a mixed solvent of water and ethanol and then reacting; the hyperbranched phosphorus-containing polyester is synthesized by two-step reaction of acrylate, phosphaphenanthrene oxide and pentaerythritol in a specific molar ratio under the action of a catalyst. The preparation method of the guide ring comprises the key steps of melt blending granulation of all the components, injection molding, segmented heat treatment and the like. The material has the advantages of high strength, high wear resistance, low warping and excellent dimensional stability, and is especially suitable for high-load working conditions such as hydraulic oil cylinders of excavators.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a novel modified nylon material, a high-strength excavator cylinder guide ring, and its preparation process. Background Technology

[0002] Nylon, as an important engineering plastic, has long been widely used in industries such as machinery, automobiles, and electronics due to its excellent mechanical strength, wear resistance, and chemical corrosion resistance. Among these, various modified materials based on polyamide resins play a crucial role in key components of hydraulic systems, such as cylinder guide rings. Excavator cylinders, as core actuators of construction machinery, require their guide rings to operate under extremely complex conditions. They not only withstand high-frequency impact loads and continuous high-pressure stress but are also exposed to harsh environmental factors such as drastic temperature changes, media corrosion, and outdoor ultraviolet aging. Traditional nylon materials, even glass fiber reinforced varieties, are gradually revealing their inherent limitations in practical applications. The material's high hygroscopicity leads to significant changes in product dimensions, affecting the sealing accuracy and operational reliability of the hydraulic system; its insufficient toughness at low temperatures and significant decrease in rigidity at high temperatures severely restrict its reliable application in a wide temperature range; furthermore, the material is prone to creep deformation under long-term continuous loads, and its wear resistance is insufficient to meet the design requirements for ultra-long service life. These material deficiencies directly affect the service life of the guide ring and the operational stability of the entire hydraulic system, and have become a long-standing and urgent technical problem in this field.

[0003] To overcome these shortcomings, the industry has invested heavily in research and development to modify nylon materials. Common modification approaches include introducing fibrous or particulate reinforcing fillers to improve strength and rigidity, adding organic or inorganic lubricants to reduce the coefficient of friction and wear rate, and blending with compatible polymeric elastomers to improve toughness. However, these conventional modification methods often only focus on improving one aspect of performance, frequently at the expense of other properties. For example, excessive fiber filling can lead to deterioration of material impact toughness and reduced processing fluidity, while also exacerbating scratches on metal-to-metal abrasive parts; the addition of small-molecule additives may cause migration and precipitation, leading to long-term performance degradation and potential contamination of hydraulic fluids; and while simple blending of elastomers can toughen the material, it inevitably causes a decrease in material modulus and heat distortion temperature. More in-depth modification research involves polymeric additives with specific topologies or nanoscale functional fillers, such as using toughening agents with star-shaped topologies to improve dispersion and interfacial bonding, or attempting to synthesize block copolymers containing specific rigid segments to balance toughness and heat resistance. Nevertheless, these solutions either have complex synthesis processes that make it difficult to achieve stable industrial production, or poor interfacial compatibility with nylon matrix resins that prevent them from fully realizing their theoretical effectiveness. As a result, their overall performance improvement effect still fails to fully meet the comprehensive and demanding requirements of high-end excavator cylinder guide rings for materials.

[0004] In summary, although existing technologies offer various approaches and solutions for nylon modification, developing a comprehensive nylon modified material that simultaneously achieves high strength, high toughness, low moisture absorption, excellent wear resistance, outstanding dimensional stability, and good resistance to environmental aging, and successfully applying it to the manufacture of high-strength excavator cylinder guide rings, remains a significant challenge for those skilled in the art. This material needs to fundamentally address the problems of unbalanced performance, insufficient long-term durability, and poor adaptability to extreme working conditions inherent in traditional materials; this is precisely the goal of this invention. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a novel modified nylon material, a high-strength excavator cylinder guide ring, and its preparation process.

[0006] In a first aspect, the present invention provides a novel modified nylon material comprising the following raw materials in parts by weight: High-temperature nylon: 80-120 parts by weight; Bicyclic guanidine-zinc metal-organic framework: 3-8 parts by weight; Hyperbranched phosphorus-containing polyester: 5-12 parts by weight; Alkali-free chopped glass fiber: 15-35 parts by weight; Boron nitride: 1-5 parts by weight; 2,6-Di-tert-butyl-p-cresol: 0.3-1.5 parts by weight; 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole: 0.5-2 parts by weight; The preparation method of the bicyclic guanidine-zinc metal-organic framework includes: A1. Dissolve 1,3-diaminoguanidine hydrochloride and 2,5-furandicarboxylic acid in a mixed solvent of water and ethanol, and adjust the pH to 6.5-7.0; add zinc nitrate hexahydrate, stir under nitrogen protection to obtain a solution; transfer the solution to a high-pressure reactor, heat to 125-135℃, and maintain the temperature. A2. The mixture was then cooled to room temperature and filtered to obtain a crystalline product. The crystalline product was washed alternately with deionized water and ethanol at 55-65℃, and finally dried under vacuum at 84-86℃.

[0007] In this invention, the construction of the bicyclic guanidine-zinc metal-organic framework is a precise self-assembly process based on coordination chemistry and crystal engineering principles. Its core reaction mechanism lies in the formation of a three-dimensional network with a regular porous structure between the organic ligand and the metal ion through strong coordination bonds. Specifically, the selected bifunctional organic ligands, namely compounds containing both guanidine and amino groups and aromatic acids containing two carboxyl groups, synergistically interact in a near-neutral water-ethanol mixed solvent system. Upon the addition of zinc metal salt, the zinc ion acts as a metal node, and its unique electronic configuration allows it to adopt multiple coordination modes. Under the high temperature and high pressure environment provided by the solvothermal reaction, the reaction kinetics and thermodynamics are optimized, driving the directional coordination of zinc ions with nitrogen and oxygen atoms on the organic ligand. Specifically, the nitrogen atom on the guanidine group and the oxygen atom after deprotonation of the aromatic acid carboxyl group act as electron donors, forming stable coordination bonds with the zinc central ion, which acts as an electron acceptor, thereby constructing a rigid metal-organic framework structure containing periodic nanopores. The pores within this framework contain uncoordinated polar functional groups. The presence of these groups not only stabilizes the crystal structure but also gives them the potential to form high-strength hydrogen bonds with the amide bonds in the nylon matrix. This is the molecular basis for the modified compound's ability to significantly improve the interfacial bonding strength and dimensional stability of the matrix material. The entire formation process relies on precisely controlled pH, reaction temperature, and time to ensure the acquisition of the target product with high crystallinity, high specific surface area, and the desired pore size.

[0008] As a preferred embodiment of the present invention, in step A1, the molar ratio of 1,3-diaminoguanidine hydrochloride, 2,5-furandicarboxylic acid and zinc nitrate hexahydrate is 1:(0.75-0.85):(0.95-1.05).

[0009] As a preferred embodiment of the present invention, in step A2, the vacuum drying time at 84-86°C is 12-14 hours.

[0010] As a preferred embodiment of the present invention, the method for preparing the hyperbranched phosphorus-containing polyester includes: B1. Trimethylolpropane triacrylate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were added to tetrahydrofuran, followed by triethylamine, and the reaction was carried out at 64-66°C under nitrogen protection. Subsequently, pentaerythritol and p-toluenesulfonic acid were added, and the reaction was carried out at 78-82°C to obtain the reaction mixture. B2. Cool the reaction mixture to room temperature, add it dropwise to n-hexane to precipitate, filter to obtain the product; wash the product with a methanol / water mixed solvent and dry it under vacuum at 68-72℃.

[0011] In this invention, the synthesis of hyperbranched phosphorus-containing polyester follows a reaction mechanism combining stepwise polymerization and Michael addition, with the core objective of constructing a macromolecule with a highly branched three-dimensional structure and terminally rich functional groups. This process mainly consists of two consecutive stages. The first stage is the key step in constructing the hyperbranched framework, based on the Michael addition reaction mechanism. Acrylic ester monomers containing multiple carbon-carbon double bonds react with phosphaphenanthrene compounds containing active hydrogen under the catalysis of an organic base. The catalyst first activates the active hydrogen in the phosphaphenanthrene compound, generating a more nucleophilic anion. This anion then attacks the carbon-carbon double bonds in the acrylate molecule, completing an addition step. Because the acrylate monomer contains multiple double bonds, this type of addition reaction can proceed in multiple directions, initially forming an intermediate with a branched structure. The second stage is the chain growth and functional group capping stage, based on the transesterification reaction mechanism. A polyol is added to the product of the first step, and the reaction is carried out in the presence of an acidic catalyst. Acid catalysts protonate the ester carbonyl group in the intermediate molecule, enhancing its electrophilicity and making it more susceptible to nucleophilic attack from the hydroxyl groups in the polyol. This leads to the formation of new ester bonds through transesterification, further extending and branching the molecular chain. Finally, by controlling the reactant ratio to ensure an excess of polyol, a large number of hydroxyl groups remain as terminal functional groups on the molecule's periphery. This unique synthetic route endows the final product with a highly branched spherical topology. The abundant phosphenanthrene rings within the structure contribute intrinsic flame retardancy and rigidity, while the numerous hydroxyl groups on the exterior significantly enhance its compatibility and reactivity with the nylon matrix and other inorganic fillers, thus providing excellent toughening and interfacial bridging in the composite material.

[0012] As a preferred embodiment of the present invention, in step B1, the molar ratio of trimethylolpropane triacrylate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and pentaerythritol is 1:(4.8-5.2):(1.8-2.2); the amount of triethylamine is 4-6% of the mass of trimethylolpropane triacrylate; and the amount of p-toluenesulfonic acid is 2-4% of the mass of trimethylolpropane triacrylate.

[0013] As a preferred embodiment of the present invention, in step B2, the vacuum drying time at 68-72°C is 10-12 hours.

[0014] In a second aspect, the present invention provides a high-strength excavator cylinder guide ring, which is made of the novel nylon modified material described above.

[0015] A third aspect of the present invention provides a method for preparing the high-strength excavator cylinder guide ring, comprising the following steps: S1. High-temperature nylon is mixed with bicyclic guanidine-zinc metal-organic framework, hyperbranched phosphorus-containing polyester, boron nitride, 2,6-di-tert-butyl-p-cresol, and 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole; melt blending is performed using a twin-screw extruder; alkali-free short glass fibers surface-treated with γ-aminopropyltriethoxysilane ethanol solution are added to the feed port on the fourth side of the extruder; the melt extruded strip is cooled in a water bath, dried, and then pelletized to obtain nylon modified material particles; S2. Dry the nylon modified material particles at 98-102℃ and use a precision injection molding machine to form a blank for the excavator cylinder guide ring; place the blank for the excavator cylinder guide ring in a heat treatment chamber and treat it at 155-165℃, then cool it down to 68-72℃, and then air cool it to room temperature.

[0016] In this invention, the preparation of the high-strength excavator cylinder guide ring is a multi-step integrated process involving physical and chemical processes. Its core mechanism lies in achieving uniform dispersion, tight compounding, and stable molding of each component at the microscale through precise processing conditions. First, in the melt blending and granulation stage, the high-temperature nylon resin undergoes plasticizing melting under heating and shearing, transforming from solid particles to a viscous flow state. In this melt environment, the pre-synthesized bicyclic guanidine-zinc metal-organic framework and modified components such as hyperbranched phosphorus-containing polyester are forcibly dispersed under the high shear force generated by the extruder screw. Among them, the hyperbranched phosphorus-containing polyester, through the polar functional groups in its molecular structure, generates strong hydrogen bond interactions with the amide bonds of the nylon melt and migrates to the interface between the inorganic fillers such as glass fibers and the nylon matrix, effectively reducing the interfacial energy and improving the adhesion. The bicyclic guanidine-zinc metal-organic framework, on the one hand, acts as a heterogeneous nucleation site, promoting the formation of a finer and more uniform crystal structure in the nylon matrix during cooling; on the other hand, its porous structure may physically adsorb nylon segments, further enhancing the interfacial bonding. Subsequently, in the injection molding stage, the molten composite material is injected into a specific cavity under high pressure. This process is not merely simple mold filling, but a complex process in which macromolecular chains undergo orientation and relaxation under the influence of the flow field. The post-molding heat treatment step is crucial. Its mechanism involves annealing at a temperature above the material's glass transition temperature but below its melting point. This provides sufficient mobility to the nylon macromolecular chain segments, allowing them to rearrange and relax, effectively eliminating internal stresses frozen during the rapid cooling injection molding process, and further refining the crystallization process. This maximizes the dimensional stability, heat resistance, and mechanical strength of the product. Every step of the entire manufacturing process is based on a deep understanding and control of the changes in the material's microstructure, ultimately ensuring that the guide ring product achieves superior performance in terms of high strength, high wear resistance, and high dimensional stability.

[0017] As a preferred technical solution of the present invention, in step S1, the temperature of the twin-screw extruder is set as follows: Zone 1 284-286℃, Zone 2 294-296℃, Zone 3 295-305℃, Zone 4 295-305℃, Zone 5 290-300℃, and the die head 285-295℃.

[0018] As a preferred embodiment of the present invention, in step S2, the treatment time at 155-165℃ is 30-40 minutes.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention has made groundbreaking progress in core mechanical properties and wear resistance. By introducing a multi-scale synergistic reinforcement system composed of a double-ring guanidine zinc metal-organic framework and surface-treated alkali-free chopped glass fibers, the tensile strength, flexural modulus, and creep resistance of the material are greatly improved, which is sufficient to withstand the extremely high impact and continuous pressure faced by the excavator cylinder during operation. It is particularly worth mentioning that the hyperbranched phosphorus-containing polyester and boron nitride work together inside the material to form a highly efficient self-lubricating and anti-wear mechanism, resulting in a guide ring with an extremely low coefficient of friction and wear rate. Bench tests show that its service life is far longer than that of guide rings made of traditional reinforced nylon materials. This not only reduces the maintenance frequency and replacement cost of the equipment, but more importantly, it significantly improves the working reliability and durability of the entire hydraulic system; (2) This invention significantly improves the dimensional stability and environmental resistance of the material, which are inherent weaknesses of traditional nylon materials. The unique porous crystal structure of the bicyclic guanidine zinc metal-organic framework can effectively adsorb and bind moisture in the nylon matrix, thereby reducing the saturated water absorption rate of the material to an extremely low level, fundamentally overcoming the problems of dimensional changes and performance degradation caused by hygroscopic expansion. At the same time, the carefully designed post-injection molding heat treatment process effectively eliminates the internal stress of the product and improves the crystal structure, so that the guide ring has extremely low warpage deformation and excellent long-term shape retention. Whether in severe cold or hot environments, or exposed to outdoor ultraviolet radiation, the material can maintain its mechanical integrity and dimensional accuracy, ensuring the sealing effectiveness and operational accuracy of the excavator cylinder under various complex working conditions; (3) The technical effects achieved by this invention are also reflected in its excellent balance of comprehensive performance and industrial value. The two key modified compounds, the bicyclic guanidine zinc metal-organic framework and the hyperbranched phosphorus-containing polyester, are not simply functional superpositions, but rather produce a profound synergistic effect in the nylon matrix. The former mainly contributes to rigidity, strength, and dimensional stability, while the latter significantly improves toughness, processing fluidity, and flame retardancy. The two complement each other, enabling the material to achieve high strength and high wear resistance without sacrificing its necessary impact toughness or processing performance. In addition, the raw materials used are all commercially available products, and the preparation process is highly compatible with existing industrial production lines, requiring no special or expensive equipment. This lays a solid foundation for large-scale, low-cost, stable, and controllable production and manufacturing, and has extremely high market promotion value and industrial application prospects. Detailed Implementation

[0020] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0021] The sources of some components in the examples and comparative examples are as follows: The high-temperature nylon was purchased from Suzhou Kelixin Plastic Raw Materials Co., Ltd. as PA46 (melting point 295℃).

[0022] The alkali-free chopped glass fiber was purchased from China Jushi Co., Ltd.

[0023] The boron nitride was purchased from Yingkou Liaohe Boron Alloy Co., Ltd.

[0024] The 2,6-di-tert-butyl-p-cresol was purchased from Tianjin Lianlong Technology Co., Ltd.

[0025] The 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole was purchased from Nanjing Hualiming Technology Co., Ltd.

[0026] The 1,3-diaminoguanidine hydrochloride was purchased from Wuhan Huaxiang Technology Co., Ltd.

[0027] The 2,5-furandicarboxylic acid was purchased from Suzhou Haofan Biotechnology Co., Ltd.

[0028] The zinc nitrate hexahydrate was purchased from Zibo Qixiang Tengda Chemical Co., Ltd.

[0029] The trimethylolpropane triacrylate was purchased from Changxing Materials Industry Co., Ltd.

[0030] The 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was purchased from Jiangsu Yake Technology Co., Ltd.

[0031] The triethylamine was purchased from Zhejiang Jianye Chemical Co., Ltd.

[0032] The pentaerythritol was purchased from Yihua Group Co., Ltd.

[0033] The p-toluenesulfonic acid was purchased from Nanjing Yaoshi Technology Co., Ltd.

[0034] Example 1: This example provides a manufacturing process for a high-strength excavator cylinder guide ring, the steps of which include: First, a bicyclic guanidine-zinc metal-organic framework was prepared. 100.0 g of 1,3-diaminoguanidine hydrochloride and 83.0 g of 2,5-furandicarboxylic acid were accurately weighed and placed in a 5 L glass reactor. 4.0 L of a mixed solvent prepared from deionized water and anhydrous ethanol at a volume ratio of 7:3 was added. A mechanical stirrer was turned on and the speed adjusted to 300 rpm. A 1.0 mol / L sodium hydroxide aqueous solution was added dropwise, and the pH of the system was monitored and adjusted to 6.8 using a precision pH meter. Then, 148.0 g of zinc nitrate hexahydrate was slowly added, and high-purity nitrogen was purged for protection. The reaction was continued at 300 rpm for 60 min until a homogeneous and transparent solution was formed. The reaction solution was transferred to a 10 L high-pressure reactor, sealed, and heated to 130 °C at a programmed rate of 1.5 °C / min, maintaining this temperature for 36 h. After the reaction was completed, the temperature was slowly lowered to 25 °C at a rate of 0.8 °C / min, and the white crystalline product was collected by filtration through a Buchner funnel. The crystals were washed three times alternately with 500 mL of hot deionized water at 60 °C and 500 mL of anhydrous ethanol at 25 °C, and filtered after each wash. The product was evenly spread in a petri dish and dried in a vacuum drying oven at 85 °C and -0.095 MPa for 13 h to obtain a white powder of bicyclic guanidine-zinc metal-organic framework.

[0035] Subsequently, hyperbranched phosphorus-containing polyester was prepared by accurately weighing 150.0 g of trimethylolpropane triacrylate and 540.0 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and dissolving them in 2.5 L of tetrahydrofuran. 9.0 g of triethylamine catalyst was added, and the reaction was carried out at 65 °C with stirring at 250 rpm for 12 h under a nitrogen atmosphere. Then, 120.0 g of pentaerythritol and 4.5 g of p-toluenesulfonic acid were added, and the temperature was raised to 80 °C for another 8 h. The reaction system was naturally cooled to 25 °C, and the viscous reaction solution was added dropwise to 8.0 L of n-hexane to precipitate the product. The white solid product was collected by vacuum filtration and washed thoroughly three times with 1.0 L of a methanol-water mixture (7:3 volume ratio). The product was placed in a vacuum drying oven and dried at 70 °C and -0.095 MPa for 11 h to obtain the hyperbranched phosphorus-containing polyester white solid.

[0036] Finally, the guide ring was prepared by adding 1000.0g of high-temperature nylon, 50.0g of self-made bicyclic guanidine-zinc metal-organic framework, 80.0g of self-made hyperbranched phosphorus-containing polyester, 30.0g of boron nitride, 8.0g of 2,6-di-tert-butyl-p-cresol, and 12.0g of 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole to a high-speed mixer and mixing at 800 rpm for 5 minutes. The premix was added through the main feed port, and 250.0g of alkali-free short glass fiber, surface-treated with 1.5wt% γ-aminopropyltriethoxysilane ethanol solution, was introduced through the fourth zone side feed port of the twin-screw extruder. The temperatures of each section of the extruder were precisely controlled as follows: Zone 1 285℃, Zone 2 295℃, Zone 3 300℃, Zone 4 300℃, Zone 5 295℃, and the die head 290℃. The screw speed was set to 220 rpm. The extruded strip was cooled in a 3m long water bath, dried with an air knife, and then granulated to obtain modified nylon granules with a diameter of 3mm and a length of 5mm. The granules were placed in a 100℃ forced-air drying oven for 4 hours, and then molded into guide ring preforms using a precision injection molding machine under conditions of 300℃ barrel temperature, 130℃ mold temperature, and 85MPa injection pressure. The preforms were placed in a programmable temperature controlled heat treatment chamber and held at 160℃ for 35 minutes, then slowly cooled to 70℃ at a rate of 0.8℃ / min, and finally air-cooled to 25℃. The preforms were then machined to the specified dimensions using a CNC machine tool.

[0037] Example 2: This example provides a manufacturing process for a high-strength excavator cylinder guide ring, the steps of which include: First, a bicyclic guanidine-zinc metal-organic framework was prepared. 100.0 g of 1,3-diaminoguanidine hydrochloride and 78.0 g of 2,5-furandicarboxylic acid were accurately weighed and placed in a 5 L glass reactor. 4.0 L of a mixed solvent prepared from deionized water and anhydrous ethanol at a volume ratio of 7:3 was added. A mechanical stirrer was turned on and the speed adjusted to 300 rpm. A 1.0 mol / L sodium hydroxide aqueous solution was added dropwise, and the pH of the system was monitored and adjusted to 6.6 using a precision pH meter. Then, 142.0 g of zinc nitrate hexahydrate was slowly added, and high-purity nitrogen was purged for protection. The reaction was continued at 300 rpm for 60 min until a homogeneous and transparent solution was formed. The reaction solution was transferred to a 10 L high-pressure reactor, sealed, and heated to 128 °C at a programmed rate of 1.5 °C / min, maintaining this temperature for 35 h. After the reaction was completed, the temperature was slowly lowered to 25 °C at a rate of 0.8 °C / min, and the white crystalline product was collected by filtration through a Buchner funnel. The crystals were washed three times alternately with 500 mL of hot deionized water at 58 °C and 500 mL of anhydrous ethanol at 25 °C, and filtered after each wash. The product was evenly spread in a petri dish and dried in a vacuum drying oven at 84 °C and -0.095 MPa for 12 h to obtain a white powder of bicyclic guanidine-zinc metal-organic framework.

[0038] Subsequently, hyperbranched phosphorus-containing polyester was prepared by accurately weighing 150.0 g of trimethylolpropane triacrylate and 520.0 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and dissolving them in 2.5 L of tetrahydrofuran. 7.5 g of triethylamine catalyst was added, and the reaction was carried out at 64 °C with stirring at 250 rpm for 11 h under a nitrogen atmosphere. Then, 115.0 g of pentaerythritol and 4.0 g of p-toluenesulfonic acid were added, and the temperature was raised to 79 °C for another 7.5 h. The reaction system was naturally cooled to 25 °C, and the viscous reaction solution was added dropwise to 8.0 L of n-hexane to precipitate. The white solid product was collected by vacuum filtration and washed thoroughly three times with 1.0 L of a methanol-water mixture (7:3 volume ratio). The product was placed in a vacuum drying oven and dried at 69 °C and -0.095 MPa for 10 h to obtain the hyperbranched phosphorus-containing polyester white solid.

[0039] Finally, the guide ring was prepared by adding 1000.0g of high-temperature nylon, 30.0g of self-made bicyclic guanidine-zinc metal-organic framework, 50.0g of self-made hyperbranched phosphorus-containing polyester, 10.0g of boron nitride, 3.0g of 2,6-di-tert-butyl-p-cresol, and 5.0g of 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole to a high-speed mixer and mixing at 800 rpm for 5 minutes. The premix was added through the main feed port, and 150.0g of alkali-free short glass fiber, surface-treated with 1.5wt% γ-aminopropyltriethoxysilane ethanol solution, was introduced through the fourth zone side feed port of the twin-screw extruder. The temperatures of each section of the extruder were precisely controlled as follows: Zone 1 284℃, Zone 2 294℃, Zone 3 298℃, Zone 4 298℃, Zone 5 292℃, and Die Head 288℃. The screw speed was set to 220 rpm. The extruded nylon strip was cooled in a 3m long water bath, dried with an air knife, and then granulated to obtain modified nylon granules with a diameter of 3mm and a length of 5mm. The granules were placed in a 99℃ forced-air drying oven for 4 hours, and then molded into guide ring preforms using a precision injection molding machine under conditions of barrel temperature 295℃, mold temperature 128℃, and injection pressure 80MPa. The preforms were placed in a programmable temperature controlled heat treatment chamber and held at 158℃ for 32 minutes, then slowly cooled to 69℃ at a rate of 0.7℃ / min, and finally air-cooled to 25℃. The preforms were then machined to the specified dimensions using a CNC machine tool.

[0040] Example 3: This example provides a manufacturing process for a high-strength excavator cylinder guide ring, the steps of which include: First, a bicyclic guanidine-zinc metal-organic framework was prepared. 100.0 g of 1,3-diaminoguanidine hydrochloride and 85.0 g of 2,5-furandicarboxylic acid were accurately weighed and placed in a 5 L glass reactor. 4.0 L of a mixed solvent prepared from deionized water and anhydrous ethanol at a volume ratio of 7:3 was added. A mechanical stirrer was turned on and the speed adjusted to 300 rpm. A 1.0 mol / L sodium hydroxide aqueous solution was added dropwise, and the pH of the system was monitored and adjusted to 6.9 using a precision pH meter. Then, 152.0 g of zinc nitrate hexahydrate was slowly added, and high-purity nitrogen was introduced for protection. The reaction was continued at 300 rpm for 60 min until a homogeneous and transparent solution was formed. The reaction solution was transferred to a 10 L high-pressure reactor, sealed, and heated to 132 °C at a programmed rate of 1.5 °C / min, maintaining this temperature for 37 h. After the reaction was completed, the temperature was slowly lowered to 25 °C at a rate of 0.8 °C / min, and the white crystalline product was collected by filtration through a Buchner funnel. The crystals were washed three times alternately with 500 mL of hot deionized water at 62°C and 500 mL of anhydrous ethanol at 25°C, with each wash followed by filtration. The product was then evenly spread in a petri dish and dried in a vacuum drying oven at 86°C and -0.095 MPa for 14 h to obtain a white powder of bicyclic guanidine-zinc metal-organic framework.

[0041] Subsequently, hyperbranched phosphorus-containing polyester was prepared by accurately weighing 150.0 g of trimethylolpropane triacrylate and 550.0 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and dissolving them in 2.5 L of tetrahydrofuran. 9.0 g of triethylamine catalyst was added, and the reaction was carried out at 66 °C with stirring at 250 rpm for 13 h under a nitrogen atmosphere. Then, 125.0 g of pentaerythritol and 5.0 g of p-toluenesulfonic acid were added, and the temperature was raised to 81 °C for another 8.5 h. The reaction system was naturally cooled to 25 °C, and the viscous reaction solution was added dropwise to 8.0 L of n-hexane to precipitate the product. The white solid product was collected by vacuum filtration and washed thoroughly three times with 1.0 L of a methanol-water mixture (7:3 volume ratio). The product was placed in a vacuum drying oven and dried at 71 °C and -0.095 MPa for 12 h to obtain the hyperbranched phosphorus-containing polyester white solid.

[0042] Finally, the guide ring was prepared by adding 1000.0g of high-temperature nylon, 80.0g of self-made bicyclic guanidine-zinc metal-organic framework, 120.0g of self-made hyperbranched phosphorus-containing polyester, 50.0g of boron nitride, 15.0g of 2,6-di-tert-butyl-p-cresol, and 20.0g of 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole to a high-speed mixer and mixing at 800 rpm for 5 minutes. The premix was added through the main feed port, and 350.0g of alkali-free short glass fibers surface-treated with 1.5wt% γ-aminopropyltriethoxysilane ethanol solution were introduced through the fourth zone side feed port of the twin-screw extruder. The temperatures of each section of the extruder were precisely controlled as follows: Zone 1 286℃, Zone 2 296℃, Zone 3 302℃, Zone 4 302℃, Zone 5 298℃, and Die Head 292℃. The screw speed was set to 220 rpm. The extruded nylon strip was cooled in a 3m long water bath, dried with an air knife, and then granulated to obtain modified nylon granules with a diameter of 3mm and a length of 5mm. The granules were placed in a 101℃ forced-air drying oven for 4 hours, and then molded into guide ring preforms using a precision injection molding machine under conditions of barrel temperature 305℃, mold temperature 132℃, and injection pressure 90MPa. The preforms were placed in a programmable temperature controlled heat treatment chamber and held at 162℃ for 38 minutes, then slowly cooled to 71℃ at a rate of 0.9℃ / min, and finally air-cooled to 25℃. The preforms were then machined to the specified dimensions using a CNC machine tool.

[0043] Comparative Example 1 The difference between this comparative example and Example 1 is that no bicyclic guanidine-zinc metal-organic framework and hyperbranched phosphorus-containing polyester were added during the preparation of the excavator cylinder guide ring.

[0044] Comparative Example 2 The difference between this comparative example and Example 1 is that melamine polyphosphate was used instead of hyperbranched phosphorus-containing polyester in the preparation of the excavator cylinder guide ring, and no bicyclic guanidine-zinc metal-organic framework was added.

[0045] Comparative Example 3 The difference between this comparative example and Example 1 is that montmorillonite and polyether ester amide were used instead of bicyclic guanidine-zinc metal-organic framework and hyperbranched phosphorus-containing polyester in the preparation of the excavator cylinder guide ring.

[0046] According to relevant national and industry standards, the performance of the high-strength excavator cylinder guide rings provided in the above embodiments and comparative examples was tested. The test methods are as follows: Tensile properties were tested using a universal testing machine with a 5A dumbbell-shaped specimen and a gauge length of 50 mm. The specimen was stretched at a constant speed of 5 mm / min until it broke. The maximum load was recorded and the tensile strength was calculated. The results are expressed in MPa.

[0047] The bending performance test adopted the three-point bending method. The sample size was 80mm×10mm×4mm, the support span was 64mm, and the indenter was pressed down at a speed of 2mm / min. The bending elastic modulus was calculated by the load-deflection curve, and the result was expressed in GPa.

[0048] Impact toughness testing was performed using a cantilever beam impact testing machine. The specimen had a standard V-notch, and the pendulum energy was 5.5 J. The energy absorbed when the specimen fractured was recorded, and the impact strength per unit area was calculated. The results are expressed in kJ / m².

[0049] The heat distortion temperature test was conducted under a bending stress of 1.82 MPa, with a uniform heating rate of 120 °C / h. The temperature at which the bending deformation of the sample reached 0.25 mm was measured, and the results are expressed in °C.

[0050] Friction and wear performance testing was conducted using a ring-block testing machine. The grinding material was a GCr15 bearing steel ring. A load of 196 N was applied at a rotational speed of 200 r / min for 120 min. The friction coefficient during the steady-state phase was recorded, and the volumetric wear rate was calculated. The wear rate was expressed as a percentage of 10. -6 The unit is mm³ / (N·m).

[0051] Flame retardancy was evaluated using the vertical burning method. A 127mm×12.7mm×1.6mm sample was used. The burning behavior after two 10s flame impacts and whether the degreased cotton below was ignited were observed. The flame retardancy rating was determined based on the burning time, self-extinguishing time and the ignition of dripping material.

[0052] For the water absorption test, a circular sample with a diameter of 50 mm and a thickness of 3 mm was completely immersed in distilled water at 50°C. After soaking for 24 hours, the sample was removed, the surface moisture was wiped off, and the sample was weighed immediately. The percentage increase in mass was calculated.

[0053] Warpage deformation was measured using a coordinate measuring machine. Eight measurement points were selected on the end face of the guide ring to evaluate the flatness deviation. The maximum deviation value was taken as the warpage deformation, and the result was expressed in mm.

[0054] The service life of the guide ring was determined by a hydraulic pulse bench test, simulating actual working conditions. The ring was continuously operated under a load spectrum of 21 MPa working pressure and 15 cycles / min until the guide ring experienced sealing failure or dimensional wear exceeding the allowable tolerance. The total operating time was recorded, and the result was expressed in hours.

[0055] The performance test data above are shown in Table 1.

[0056] Table 1 Performance Test Results

[0057] As can be seen from the above, the test results show that Examples 1-3, by introducing two novel modified compounds, namely, bicyclic guanidine-zinc metal-organic framework and hyperbranched phosphorus-containing polyester, have comprehensively solved the key technical problems existing in the application of traditional nylon materials in excavator cylinder guide rings.

[0058] In terms of mechanical properties, the tensile strength of Example 1 reached 186 MPa and the flexural modulus reached 9.9 GPa, which were significantly higher than the 138 MPa and 6.8 GPa of Comparative Example 1, proving that the two modified compounds formed an effective multi-scale synergistic reinforcement system with glass fiber, solving the problem of insufficient strength of traditional materials.

[0059] In terms of wear resistance, the wear rate of Example 1 was only 2.0 × 10⁻⁶. -6 mm 3 / (N·m), which is much lower than the 5.8×10 of Comparative Example 1. -6 mm 3 / (N·m) indicates that the novel modified compound and boron nitride together construct an efficient lubrication and anti-wear mechanism, overcoming the technical bottleneck of poor material wear resistance.

[0060] In terms of dimensional stability, Example 1 showed a water absorption rate as low as 1.7% and a warpage deformation controlled within 0.14 mm, while Comparative Example 1 achieved 3.3% and 0.47 mm, respectively. This is attributed to the adsorption and fixation of water molecules by the porous structure of the bicyclic guanidine-zinc metal-organic framework and the improvement of interfacial compatibility by the hyperbranched phosphorus-containing polyester, which effectively solved the problems of dimensional changes and processing warpage caused by moisture absorption in nylon materials.

[0061] Regarding heat resistance and durability, Example 1 achieved a heat distortion temperature of 278°C and a guide ring service life of 3900 hours, significantly improved compared to Comparative Example 1's 248°C and 1750 hours. This demonstrates that the two modified compounds improved the material's thermal stability and long-term performance by optimizing crystallization behavior and interfacial bonding. In particular, Comparative Example 2, using a traditional flame retardant, achieved a V-0 flame retardant rating, but its mechanical properties and wear resistance were significantly inferior to the examples. Comparative Example 3, using a common toughening agent, showed some improvement in impact toughness, but its strength, rigidity, and heat resistance remained insufficient. This further highlights the unique advantages of the two novel modified compounds in achieving a balance of comprehensive material performance, successfully solving the technical challenge of traditional modification schemes failing to simultaneously achieve multiple performance characteristics.

Claims

1. A novel modified nylon material, characterized in that, Including the following parts by weight of raw materials: High-temperature nylon: 80-120 parts by weight; Bicyclic guanidine-zinc metal-organic framework: 3-8 parts by weight; Hyperbranched phosphorus-containing polyester: 5-12 parts by weight; Alkali-free chopped glass fiber: 15-35 parts by weight; Boron nitride: 1-5 parts by weight; 2,6-Di-tert-butyl-p-cresol: 0.3-1.5 parts by weight; 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole: 0.5-2 parts by weight; The preparation method of the bicyclic guanidine-zinc metal-organic framework includes: A1. Dissolve 1,3-diaminoguanidine hydrochloride and 2,5-furandicarboxylic acid in a mixed solvent of water and ethanol, and adjust the pH to 6.5-7.0; add zinc nitrate hexahydrate, stir under nitrogen protection to obtain a solution; transfer the solution to a high-pressure reactor, heat to 125-135℃, and maintain the temperature. A2. The mixture was then cooled to room temperature and filtered to obtain the crystalline product. The crystalline product was washed alternately with deionized water and ethanol at 55-65℃, and finally dried under vacuum at 84-86℃.

2. The novel nylon modified material according to claim 1, characterized in that, In step A1, the molar ratio of 1,3-diaminoguanidine hydrochloride, 2,5-furandicarboxylic acid and zinc nitrate hexahydrate is 1:(0.75-0.85):(0.95-1.05).

3. The novel nylon modified material according to claim 1, characterized in that, In step A2, the vacuum drying time at 84-86℃ is 12-14 hours.

4. The novel nylon modified material according to claim 1, characterized in that, The preparation method of the hyperbranched phosphorus-containing polyester includes: B1. Trimethylolpropane triacrylate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were added to tetrahydrofuran, followed by triethylamine, and the reaction was carried out at 64-66°C under nitrogen protection. Subsequently, pentaerythritol and p-toluenesulfonic acid were added, and the reaction was carried out at 78-82°C to obtain the reaction mixture. B2. Cool the reaction mixture to room temperature, add it dropwise to n-hexane to precipitate, filter to obtain the product; wash the product with a methanol / water mixed solvent and dry it under vacuum at 68-72℃.

5. The novel nylon-modified material according to claim 4, characterized in that, In step B1, the molar ratio of trimethylolpropane triacrylate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and pentaerythritol is 1:(4.8-5.2):(1.8-2.2); the amount of triethylamine used is 4-6% of the mass of trimethylolpropane triacrylate; and the amount of p-toluenesulfonic acid used is 2-4% of the mass of trimethylolpropane triacrylate.

6. The novel nylon-modified material according to claim 4, characterized in that, In step B2, the vacuum drying time at 68-72℃ is 10-12 hours.

7. A high-strength excavator cylinder guide ring, characterized in that, It is prepared using the novel nylon modified material according to any one of claims 1-6.

8. A method for preparing a high-strength excavator cylinder guide ring according to claim 7, characterized in that, step... include: S1. High-temperature nylon is mixed with bicyclic guanidine-zinc metal-organic framework, hyperbranched phosphorus-containing polyester, boron nitride, 2,6-di-tert-butyl-p-cresol, and 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole; melt blending is performed using a twin-screw extruder; alkali-free short glass fibers surface-treated with γ-aminopropyltriethoxysilane ethanol solution are added to the feed port on the fourth side of the extruder; the melt extruded strip is cooled in a water bath, dried, and then pelletized to obtain nylon modified material particles; S2. Dry the nylon modified material particles at 98-102℃ and use a precision injection molding machine to form a blank for the excavator cylinder guide ring; place the blank for the excavator cylinder guide ring in a heat treatment chamber and treat it at 155-165℃, then cool it down to 68-72℃, and then air cool it to room temperature.

9. The preparation method according to claim 8, characterized in that, In step S1, the temperature of the twin-screw extruder is set as follows: Zone 1 284-286℃, Zone 2 294-296℃, Zone 3 295-305℃, Zone 4 295-305℃, Zone 5 290-300℃, and Die head 285-295℃.

10. The preparation method according to claim 8, characterized in that, In step S2, the treatment time is 30-40 minutes at 155-165℃.

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