Medium-resistant high-performance polyurethane elastomer composite material and preparation method thereof

Abstract

The application discloses a kind of medium erosion resistant high-performance polyurethane elastomer composite material and preparation method thereof, belong to high polymer material technical field.Composite material is made of composite silicon dioxide A, composite silicon dioxide B, diphenyl methane diisocyanate, polycarbonate dihydric alcohol, polytetrahydrofuran dihydric alcohol, polyamide-amine dendritic polymer, 1,4-butanediol, organic bismuth catalyst and auxiliary agent;Composite silicon dioxide A is PEG2000 grafted nano-silica, and composite silicon dioxide B is PCL800-OH grafted nano-silica.The application forms guiding mechanism by constructing "hard segment-stable zone-soft segment" three-phase structure, and makes polyamide-amine dendritic polymer accurately positioned in interface area using the polarity difference of composite silicon dioxide A and B, effectively solves the technical problems such as the fast mechanical property attenuation of traditional polyurethane under severe medium environment, additive easy precipitation, and realizes the synergistic improvement of high strength and high medium resistance.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and relates to a high-performance polyurethane elastomer composite material resistant to media erosion and its preparation method. Background Technology

[0002] Polyurethane elastomer (TPU), as a type of polymer material that combines the high elasticity of rubber with the high strength of engineering plastics, has been widely used in many key fields such as military, petrochemical, automobile manufacturing, medical, and cable industries due to its excellent mechanical properties, wear resistance, processing adaptability and recyclability. It has become an indispensable core material, especially in scenarios where it needs to come into contact with oil, water and various chemical media, such as flexible oil (water) reservoirs, oil (water) hoses and seals.

[0003] In the military industry, flexible oil storage tanks and oil pipelines are key equipment for field logistics support. They need to withstand harsh conditions such as high temperature, high humidity, and rich oil in complex field environments. The material properties of these materials directly affect the safety and reliability of oil storage and transportation. In the civilian sector, tank linings in the petrochemical industry, fuel system components in the automotive industry, and chemical media delivery pipelines in the medical field also place extremely high demands on the resistance of polyurethane elastomers to media erosion.

[0004] However, existing polyurethane elastomer materials still face significant technical bottlenecks in practical applications. On the one hand, traditional polyurethane materials mostly rely on polyether polyols or polyester polyols as soft segment raw materials. Polyether polyurethanes have good hydrolysis resistance but insufficient mechanical properties and high-temperature resistance, while polyester polyurethanes have excellent mechanical strength but weak hydrolysis resistance. Neither can simultaneously achieve resistance to various media erosion and long-term performance stability. On the other hand, existing materials generally use weak forces such as hydrogen bonds to regulate the microphase separation structure. Under harsh environments such as heating, water-rich, and oil-rich conditions, the additives in the materials are prone to precipitation, leading to a significant decrease in key mechanical properties such as tensile strength and elongation at break, or even material failure, which seriously affects the service life and safety of equipment or products. Summary of the Invention

[0005] The purpose of this invention is to provide a high-performance polyurethane elastomer composite material resistant to media erosion and its preparation method. By constructing a three-phase structure of "hard segment-stable region-soft segment" and a polarity guiding mechanism, the invention solves the technical problems of rapid mechanical property decay and easy precipitation of additives in traditional polyurethane materials under harsh media environments, thereby achieving a synergistic improvement in high strength and high media resistance.

[0006] The objective of this invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a high-performance polyurethane elastomer composite material resistant to media erosion, comprising the following raw materials: composite silica A, composite silica B, diphenylmethane diisocyanate, polycarbonate diol, polytetrahydrofuran diol, polyamide-amine dendritic polymer, 1,4-butanediol, organic bismuth catalyst and additives. The composite silica A is PEG2000 grafted modified nano silica; The composite silica B is PCL800-OH grafted modified nano silica.

[0007] Preferably, the polyurethane elastomer composite material comprises the following raw materials in parts by weight: 4.5-7.5 parts of composite silica A, 6.0-10.0 parts of composite silica B, 315-325 parts of diphenylmethane diisocyanate, 340-345 parts of polycarbonate diol, 145-150 parts of polytetrahydrofuran diol, 4.5-6.0 parts of polyamide-amine dendritic polymer, 48-52 parts of 1,4-butanediol, 0.15-0.25 parts of organic bismuth catalyst, and 12-18 parts of additives.

[0008] Preferably, the composite silica A has a particle size of 15-25 nm, and the PEG2000 grafting density is 1.2-1.8 chains / nm. 2 .

[0009] Preferably, the composite silica B has a particle size of 20-30 nm and a PCL800-OH grafting density of 0.8-1.2 chains / nm. 2 .

[0010] Preferably, the polyamide-amine dendritic polymer is a third-generation polyamide-amine dendritic polymer.

[0011] Preferably, the additives include 8-12 parts of hydrolytic stabilizer, 2.5-3.5 parts of antioxidant and 1.5-2.5 parts of light stabilizer.

[0012] Preferably, the hydrolysis stabilizer is carbodiimide, the antioxidant is antioxidant 1010, and the light stabilizer is UV-326.

[0013] Secondly, the present invention provides a method for preparing the above-mentioned high-performance polyurethane elastomer composite material resistant to media erosion, comprising the following steps: S1. Vacuum dehydrate polycarbonate diol and polytetrahydrofuran diol, melt filter diphenylmethane diisocyanate, dissolve polyamide-amine dendritic polymer in N,N-dimethylformamide to prepare a solution, and vacuum dry composite silica A and composite silica B. S2. A high-polarity pre-dispersion was prepared by high-speed dispersion and ultrasonic treatment of composite silica A and polyamide-amine dendritic polymer solution. A low-polarity pre-dispersion was prepared by heating and premixing composite silica B with polycarbonate diol and polytetrahydrofuran diol. S3. First, react the low polarity predispersant with diphenylmethane diisocyanate to synthesize a prepolymer. Then, add a hydrolysis stabilizer and dropwise add a high polarity predispersant to construct a stable region. Subsequently, add 1,4-butanediol and an organic bismuth catalyst to carry out a chain extension reaction. Finally, add an antioxidant and a light stabilizer to complete the stabilization treatment and remove the solvent. S4. The finished product is obtained by extrusion granulation, vacuum drying and curing.

[0014] Preferably, in step S3, before adding the high polarity predispersant, the temperature of the reaction system is controlled at 75-80℃ and kept at that temperature for 25-35 minutes; then the temperature is raised to 88-92℃, and the high polarity predispersant is added to the prepolymer at a dropping rate of 0.40-0.50 parts / minute. After the addition is complete, the reaction is carried out at 90±1℃ for 1.3-1.7 hours.

[0015] Preferably, in step S4, the curing process adopts a stepped heating method, first curing at 60±2℃ for 22-26 hours, and then heating to 80±1℃ at a heating rate of 0.8-1.2℃ / min and holding at that temperature for 45-49 hours.

[0016] The beneficial effects of this invention are: (1) The polyurethane of this invention breaks through the limitations of the traditional two-phase structure of "hard segment-soft segment" and constructs a three-phase structure of "hard segment-stable region-soft segment". The rigid segment formed by the reaction of diphenylmethane diisocyanate and 1,4-butanediol is used as the hard segment, and the flexible segment formed by polycarbonate diol and polytetrahydrofuran diol is used as the soft segment. Innovatively, polyamide-amine dendritic polymer is introduced as the building unit of the stable region, which is precisely positioned at the interface between the hard segment and the soft segment. In this three-phase structure, the numerous terminal amino groups of the dendritic polymer form a dense hydrogen bond network with the hard segment, which significantly enhances the interfacial bonding force. Its internal three-dimensional cavity structure effectively locks various auxiliary molecules through intermolecular forces, preventing their migration and precipitation during long-term use. At the same time, the dendritic polymer forms a dense molecular barrier in the interfacial region, which greatly extends the penetration path of molecules of oil, water and other media. This innovative three-phase structure effectively solves the technical problem of rapid performance degradation and short service life of traditional polyurethane in harsh media environments.

[0017] (2) This invention innovatively combines composite silica A, composite silica B, and polyamide-amine dendritic polymer to construct a precise positioning system through a polarity-driven migration mechanism. Composite silica A (PEG2000 grafted modification) has high polarity and excellent compatibility with high-polarity hard segment regions, spontaneously migrating to hard segment-rich regions during the polymerization reaction; composite silica B (PCL800-OH grafted modification) has medium polarity and good compatibility with medium-low polarity soft segment regions, spontaneously migrating to soft segment distribution regions in the reaction system. This spontaneous migration behavior based on the principle of polarity matching enables the two composite silicas to form a continuous polarity gradient distribution from hard segments to soft segments within the material. Driven by this polarity gradient, the polyamide-amine dendritic polymer is precisely guided and stably positioned at the hard segment / soft segment interface region, forming a stable interface layer with uniform molecular-level distribution. This polar-driven migration mechanism effectively solves the problem of easy aggregation of high-volume dendritic polymers in the polymer matrix, enabling a significant increase in dendritic polymer content while reducing harmful aggregation, and greatly improving interfacial coverage and interfacial bonding strength. The gradient structure formed by the synergistic effect of these three factors not only significantly improves the mechanical properties of the material but also greatly enhances its resistance to media erosion. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0019] The following descriptions of some of the raw materials used in the examples and comparative examples are as follows: The polycarbonate diol has a molecular weight of 1500 g / mol and a hydroxyl value of 72 mg KOH / g; The isocyanate content of diphenylmethane diisocyanate is 33.5%; The molecular weight of polytetrahydrofuran diol is 800 g / mol.

[0020] Example 1

[0021] A high-performance polyurethane elastomer composite material resistant to media erosion comprises the following components in parts by weight: 6 parts of composite silica A, 8 parts of composite silica B, 320 parts of diphenylmethane diisocyanate, 342.5 parts of polycarbonate diol, 147.5 parts of polytetrahydrofuran diol, 5 parts of third-generation polyamide-amine dendritic polymer, 50 parts of 1,4-butanediol, 0.2 parts of organic bismuth catalyst, 10 parts of carbodiimide (auxiliary agent), 3 parts of antioxidant 1010 (auxiliary agent), 2 parts of UV-326 (auxiliary agent), and 20 parts of N,N-dimethylformamide.

[0022] The preparation of composite silica A includes the following steps: C1. Amination treatment: 500 parts of fumed silica (specific surface area 250 m²) 2 / g) and 1500 parts of anhydrous toluene were added to the reaction vessel, purged with nitrogen three times, and heated to 70°C and stirred for 1 hour; 40 parts of 3-aminopropyltriethoxysilane were slowly added dropwise, and after the addition was complete, the temperature was raised to 80°C and reacted for 6 hours; after filtration, the mixture was washed three times with anhydrous toluene and dried under vacuum at 60°C for 12 hours to obtain aminated silica.

[0023] C2. Isocyanation: 480 parts of aminated silica and 1200 parts of anhydrous toluene were added to a reaction vessel and stirred and dispersed at 60°C for 30 min; 25 parts of toluene diisocyanate were added dropwise, and after the addition was complete, 0.8 parts of dibutyltin dilaurate were added, and the reaction was carried out at 70°C for 2 h; after precipitation with acetone, the mixture was filtered and dried under vacuum at 60°C for 8 h to obtain isocyanated silica.

[0024] C3. Polyethylene glycol grafting: 450 parts of isocyanate-modified silica and 1000 parts of anhydrous toluene were added to a reaction vessel and stirred and dispersed at 65°C for 45 min; 150 parts of polyethylene glycol 2000 (hydroxyl value 55 mg KOH / g) were added dropwise, and the temperature was raised to 75°C for 4 h after the addition was complete; the mixture was purified using a dialysis bag with a molecular weight cutoff of 10000 and freeze-dried at -40°C for 24 h to obtain composite silica A.

[0025] The particle size of composite silica A is 20 nm, and the grafting density of polyethylene glycol 2000 is 1.5 chains / nm. 2 The specific surface area of ​​composite silica A is 140 m² / g.

[0026] The preparation of composite silica B includes the following steps: D1. Isocyanate treatment: 600 parts of fumed silica and 1800 parts of anhydrous xylene were added to a reaction vessel and stirred and dispersed at 85°C for 1 hour under nitrogen protection; 35 parts of 3-propyltriethoxysilane were added dropwise, and after the addition was complete, the temperature was raised to 90°C and reacted for 5 hours; after filtration, the mixture was washed three times with anhydrous xylene and dried under vacuum at 70°C for 10 hours to obtain isocyanate silica.

[0027] D2. Polycaprolactone grafting: 550 parts of isocyanate-modified silica and 1500 parts of anhydrous xylene were added to a reaction vessel and stirred and dispersed at 90℃ for 40 min; 120 parts of PCL800-OH (hydroxyl value 140 mg KOH / g) were added dropwise, and after the addition was complete, 0.8 parts of dibutyltin dilaurate were added, and the reaction was carried out at 100℃ for 3 h; the temperature was lowered to 60℃ and 4 parts of benzoyl chloride were added to terminate the reaction, and the silica was purified by precipitation with anhydrous ethanol and dried under vacuum at 50℃ for 12 h to obtain polycaprolactone grafted silica.

[0028] D3. Surface modification: Add 500 parts of polycaprolactone-grafted silica and 1000 parts of anhydrous tetrahydrofuran to the reactor and stir at 40°C for 30 min; add 5 parts of 3-propyltriethoxysilane dropwise and react at 50°C for 2 h; remove the solvent by rotary evaporation and dry under vacuum at 60°C for 8 h to obtain composite silica B.

[0029] The composite silica B has a particle size of 25 nm, and the PCL800-OH grafting density is 1.0 chains / nm. 2 The hydroxyl value of composite silica B is 40 mg KOH / g.

[0030] A method for preparing a high-performance polyurethane elastomer composite material resistant to media erosion includes the following steps: S1. Raw material pretreatment; Polycarbonate diol (342.5 parts): Add to a vacuum dehydration kettle, dehydrate under vacuum at 120℃ and 200Pa for 2 hours, and cool to 80℃ for later use; Polytetrahydrofurandiol (147.5 parts): Add to a vacuum dehydration vessel and dehydrate under vacuum at 110℃ and 200Pa for 2 hours. Cool to 80℃ for later use. Diphenylmethane diisocyanate (320.0 parts): Add to a melting vessel, heat to 65°C to melt, filter through a 0.5μm filter membrane, purge with nitrogen for protection, and keep at 60°C for later use; Polyamide-amine dendritic polymer (5.0 parts): Mixed with N,N-dimethylformamide (20.0 parts), stirred until completely dissolved, to prepare a 20% concentration solution, and dried under vacuum at 80℃ and 100Pa for 4 hours for later use; Composite silica A (6.0 parts): Add to a vacuum drying oven and dry at 80℃ and 100Pa for 2 hours for later use; Composite silica B (8.0 parts): Add to a vacuum drying oven and dry at 70℃ and 100Pa for 2 hours for later use.

[0031] S2, Preparation of pre-dispersion system; 1. High polarity pre-dispersion: Add composite silica A (6.0 parts) to a high-speed disperser, add the above dendritic polymer / N,N-dimethylformamide solution (25.0 parts), disperse at 1500 rpm for 15 min, then transfer to a 20 kHz ultrasonic device for 10 min, and store at 40℃ under nitrogen protection. 2. Low polarity pre-dispersion: Take polycarbonate diol (342.5 parts) and polytetrahydrofuran diol (147.5 parts) and add them to the premixing vessel. Heat to 110°C and add composite silica B (8.0 parts). Stir and premix at 300 rpm for 20 min, then degas under vacuum at 100 Pa for 10 min and keep warm at 80°C for later use.

[0032] S3, polymerization reaction; 1. Synthesis of prepolymer: The low polarity predispersant was transferred into a reactor and dehydrated under vacuum at 110°C and 100Pa for 30 min to remove trace amounts of water from the system. After cooling to 75°C, diphenylmethane diisocyanate (320.0 parts) was added dropwise at a uniform rate. After the addition was complete, the temperature was raised to 85°C and reacted for 2 h to obtain the terminal isocyanate group prepolymer.

[0033] 2. Construction of the stable region: The isocyanate-terminated prepolymer was cooled to 78°C, and carbodiimide (10.0 parts) was added and kept at the temperature for 30 min to ensure uniform dispersion. Then the temperature was raised to 90°C, and a high polarity predispersant was added dropwise at a rate of 0.45 parts / min. After the addition was completed, the reaction was carried out at 90°C for 1.5 h to construct a stable region at the hard segment-soft segment interface. At this time, the material is a prepolymer system containing the stable region.

[0034] 3. Chain extension reaction: The prepolymer system containing the stable region was cooled to 75°C. 1,4-Butanediol (50.0 parts) and organic bismuth catalyst (0.20 parts) were mixed and quickly added to the reactor. The mixture was stirred at 800 rpm for 5 min to ensure uniform mixing. The reaction was carried out at 85°C for 45 min to allow the molecular chains to grow fully and obtain the high molecular weight polyurethane primary product.

[0035] 4. Stabilization treatment: Cool the primary polyurethane product to 65℃, add antioxidant 1010 (3.0 parts) and light stabilizer UV-326 (2.0 parts), stir at 200rpm for 15min to disperse it evenly, remove N,N-dimethylformamide solvent under vacuum of 200Pa for 30min to obtain a uniform and stable polyurethane melt, and keep it at 60℃.

[0036] S4, Post-processing.

[0037] 1. Extrusion Granulation: The polyurethane melt, which was kept warm in step S3, is conveyed to a parallel twin-screw extruder through a 60℃ insulated pipeline. The temperatures of each section are set as follows: feed section 85℃, compression section 110℃, melting section 135℃, metering section 148℃, and die head 142℃; screw speed 210 rpm, feed speed 55 rpm, and melt index controlled at 9 g / 10 min. After being extruded through a Φ3mm die, the material is cut into cylindrical granules with a diameter of 3.0 mm and a length of 3.5 mm; the granules are then dehydrated in a centrifugal dewatering machine (800 rpm) for 10 min and dried with hot air at 60℃ for 1 h.

[0038] 2. Vacuum drying: Transfer the hot-air dried particles into a vacuum drying oven and dry them at 60℃ and 100Pa for 16 hours to thoroughly remove residual moisture from the interior.

[0039] 3. Step-by-step maturation: The vacuum-dried granules are placed in a forced-air drying oven and first matured at 60℃ for 24 hours to promote the initial regular arrangement of molecular chains. Then, the temperature is increased to 80℃ at a rate of 1.0℃ / min and held for 48 hours to make the microphase structure more perfect. Finally, after cooling to room temperature, the product is packaged to obtain the finished product.

[0040] Example 2

[0041] A high-performance polyurethane elastomer composite material resistant to media erosion comprises the following components in parts by weight: 4.5 parts of composite silica A, 6 parts of composite silica B, 315 parts of diphenylmethane diisocyanate, 340 parts of polycarbonate diol, 145 parts of polytetrahydrofuran diol, 4.5 parts of third-generation polyamide-amine dendritic polymer, 48 parts of 1,4-butanediol, 0.15 parts of organobismuth catalyst, 8 parts of carbodiimide (auxiliary agent), 2.5 parts of antioxidant 1010 (auxiliary agent), 1.5 parts of UV-326 (auxiliary agent), and 18 parts of N,N-dimethylformamide.

[0042] The preparation of composite silica A includes the following steps: C1. Amination treatment: 480 parts of fumed silica (specific surface area 245m²) were subjected to amination. 2 / g) and 1400 parts of anhydrous toluene were added to the reactor, purged with nitrogen three times, and heated to 68℃ and stirred for 1h; 38 parts of 3-aminopropyltriethoxysilane were slowly added dropwise, and after the addition was complete, the temperature was raised to 78℃ and reacted for 5.5h; after filtration, the mixture was washed three times with anhydrous toluene and dried under vacuum at 60℃ for 12h to obtain aminated silica.

[0043] C2. Isocyanation: 460 parts of aminated silica and 1100 parts of anhydrous toluene were added to a reaction vessel and stirred and dispersed at 58°C for 30 min; 23 parts of toluene diisocyanate were added dropwise, and after the addition was complete, 0.75 parts of dibutyltin dilaurate were added, and the reaction was carried out at 68°C for 2 h; after precipitation with acetone, the mixture was filtered and dried under vacuum at 60°C for 8 h to obtain isocyanated silica.

[0044] C3. Polyethylene glycol grafting: 430 parts of isocyanate-modified silica and 950 parts of anhydrous toluene were added to a reaction vessel and stirred and dispersed at 63°C for 45 min; 145 parts of polyethylene glycol 2000 (hydroxyl value 54 mg KOH / g) were added dropwise, and after the addition was complete, the temperature was raised to 73°C and reacted for 4 h; purified with a dialysis bag with a molecular weight cutoff of 10000, and freeze-dried at -40°C for 24 h to obtain composite silica A.

[0045] The particle size of composite silica A is 15 nm, and the grafting density of polyethylene glycol 2000 is 1.2 chains / nm. 2 The specific surface area of ​​composite silica A is 135 m². 2 / g.

[0046] The preparation of composite silica B includes the following steps: D1. Isocyanate treatment: 580 parts of fumed silica and 1700 parts of anhydrous xylene were added to a reaction vessel and stirred and dispersed at 83°C for 1 h under nitrogen protection; 33 parts of 3-propyltriethoxysilane were added dropwise, and after the addition was complete, the temperature was raised to 88°C and reacted for 5 h; after filtration, the mixture was washed 3 times with anhydrous xylene and dried under vacuum at 70°C for 10 h to obtain isocyanate silica.

[0047] D2. Polycaprolactone grafting: 530 parts of isocyanate-modified silica and 1400 parts of anhydrous xylene were added to a reaction vessel and stirred and dispersed at 88°C for 40 min; 115 parts of PCL800-OH (hydroxyl value 138 mg KOH / g) were added dropwise, and after the addition was complete, 0.75 parts of dibutyltin dilaurate were added, and the reaction was carried out at 98°C for 3 h; the temperature was lowered to 58°C and 3.8 parts of benzoyl chloride were added to terminate the reaction, and the silica was purified by precipitation with anhydrous ethanol and dried under vacuum at 50°C for 12 h to obtain polycaprolactone grafted silica.

[0048] D3. Surface modification: 480 parts of polycaprolactone-grafted silica and 950 parts of anhydrous tetrahydrofuran were added to the reactor and stirred at 38°C for 30 min; 4.5 parts of 3-propyltriethoxysilane were added dropwise and reacted at 48°C for 2 h; the solvent was removed by rotary evaporation and dried under vacuum at 60°C for 8 h to obtain composite silica B.

[0049] The composite silica B has a particle size of 20 nm and a PCL800-OH grafting density of 0.8 chains / nm. 2 The hydroxyl value of composite silica B is 38 mg KOH / g.

[0050] A method for preparing a high-performance polyurethane elastomer composite material resistant to media erosion includes the following steps: S1. Raw material pretreatment; Polycarbonate diol (340 parts): Add to a vacuum dehydration kettle, dehydrate under vacuum at 118°C and 200Pa for 2 hours, and cool to 80°C for later use; Polytetrahydrofurandiol (145 parts): Add to a vacuum dehydration kettle, dehydrate under vacuum at 108℃ and 200Pa for 2 hours, and cool to 80℃ for later use; Diphenylmethane diisocyanate (315 parts): Add to a melting vessel, heat to 63°C to melt, filter through a 0.5μm filter membrane, purge with nitrogen for protection, and keep at 58°C for later use; Polyamide-amine dendritic polymer (4.5 parts): Mixed with N,N-dimethylformamide (18 parts), stirred until completely dissolved, to prepare a 20% concentration solution, and dried under vacuum at 78℃ and 100Pa for 4 hours for later use; Composite silica A (4.5 parts): Add to a vacuum drying oven and dry at 78℃ and 100Pa for 2 hours for later use; Composite silica B (6 parts): Add to a vacuum drying oven and dry at 68℃ and 100Pa for 2 hours for later use.

[0051] S2, Preparation of pre-dispersion system; 1. High polarity pre-dispersion: Add composite silica A (4.5 parts) to a high-speed disperser, add the above dendritic polymer / N,N-dimethylformamide solution (22.5 parts), disperse at 1450 rpm for 15 min, then transfer to a 20 kHz ultrasonic device for 10 min, and store at 40℃ under nitrogen protection. 2. Low polarity pre-dispersion: Take polycarbonate diol (340 parts) and polytetrahydrofuran diol (145 parts) and add them to the premixing vessel. Heat to 108°C and add composite silica B (6 parts). Stir and premix at 280 rpm for 20 min, then degas under vacuum at 100 Pa for 10 min and keep warm at 80°C for later use.

[0052] S3, polymerization reaction; 1. Synthesis of prepolymer: The low polarity predispersant was transferred into a reactor and dehydrated under vacuum at 108°C and 100Pa for 30 min to remove trace amounts of water from the system. After cooling to 73°C, diphenylmethane diisocyanate (315 parts) was added dropwise at a uniform rate. After the addition was complete, the temperature was raised to 83°C and reacted for 2 h to obtain the terminal isocyanate group prepolymer.

[0053] 2. Construction of the stable region: The isocyanate-terminated prepolymer was cooled to 75°C, and carbodiimide (8 parts) was added and kept at the temperature for 35 min to ensure uniform dispersion. Then the temperature was raised to 88°C, and a high polarity pre-dispersion was added dropwise at a rate of 0.40 parts / min. After the addition was completed, the reaction was carried out at 89°C for 1.7 h to construct a stable region at the hard-soft segment interface. At this time, the material is a prepolymer system containing the stable region.

[0054] 3. Chain extension reaction: The prepolymer system containing the stable region was cooled to 73°C. 1,4-Butanediol (48 parts) and organic bismuth catalyst (0.15 parts) were mixed and quickly added to the reactor. The mixture was stirred at 750 rpm for 5 min to ensure uniform mixing. The reaction was carried out at 83°C for 45 min to allow the molecular chains to grow fully and obtain high molecular weight polyurethane primary product.

[0055] 4. Stabilization treatment: Cool the primary polyurethane product to 63℃, add antioxidant 1010 (2.5 parts) and light stabilizer UV-326 (1.5 parts), stir at 190 rpm for 15 min to disperse it evenly, remove N,N-dimethylformamide solvent under vacuum of 200 Pa for 30 min to obtain a uniform and stable polyurethane melt, and keep it at 58℃.

[0056] S4, Post-processing.

[0057] 1. Extrusion Granulation: The polyurethane melt, which was kept warm in step S3, is conveyed to a parallel twin-screw extruder through a 58℃ insulated pipeline. The temperatures of each section are set as follows: feed section 83℃, compression section 108℃, melting section 133℃, metering section 146℃, and die head 140℃; the screw speed is 200 rpm, the feed speed is 55 rpm, and the melt index is controlled at 8.5 g / 10 min. After the material is extruded through a Φ3mm die, it is cut into cylindrical granules with a particle size of 2.9 mm and a length of 3.3 mm; the granules are dehydrated in a centrifugal dewatering machine (780 rpm) for 10 min and then dried with hot air at 60℃ for 1 h.

[0058] 2. Vacuum drying: Transfer the hot-air dried particles into a vacuum drying oven and dry them at 58℃ and 100Pa for 16 hours to thoroughly remove residual moisture from the interior.

[0059] 3. Step-by-step maturation: The vacuum-dried granules are placed in a forced-air drying oven and first matured at 58℃ for 26 hours to promote the initial regular arrangement of molecular chains. Then, the temperature is increased to 79℃ at a rate of 0.8℃ / min and held for 49 hours to make the microphase structure more perfect. Finally, after cooling to room temperature, the product is packaged to obtain the finished product.

[0060] Example 3

[0061] A high-performance polyurethane elastomer composite material resistant to media erosion comprises the following components in parts by weight: 7.5 parts of composite silica A, 10 parts of composite silica B, 325 parts of diphenylmethane diisocyanate, 345 parts of polycarbonate diol, 150 parts of polytetrahydrofuran diol, 6 parts of third-generation polyamide-amine dendritic polymer, 52 parts of 1,4-butanediol, 0.25 parts of organic bismuth catalyst, 12 parts of carbodiimide (auxiliary agent), 3.5 parts of antioxidant 1010 (auxiliary agent), 2.5 parts of UV-326 (auxiliary agent), and 24 parts of N,N-dimethylformamide.

[0062] The preparation of composite silica A includes the following steps: C1. Amination treatment: 520 parts of fumed silica (specific surface area 255 m²) were subjected to amination. 2 / g) and 1600 parts of anhydrous toluene were added to the reactor, purged with nitrogen three times, and heated to 72°C and stirred for 1 h; 42 parts of 3-aminopropyltriethoxysilane were slowly added dropwise, and after the addition was complete, the temperature was raised to 82°C and reacted for 6.5 h; after filtration, the mixture was washed three times with anhydrous toluene and dried under vacuum at 60°C for 12 h to obtain aminated silica.

[0063] C2. Isocyanation: 500 parts of aminated silica and 1300 parts of anhydrous toluene were added to a reaction vessel and stirred and dispersed at 62°C for 30 min; 27 parts of toluene diisocyanate were added dropwise, and after the addition was complete, 0.85 parts of dibutyltin dilaurate were added, and the reaction was carried out at 72°C for 2 h; after precipitation with acetone, the mixture was filtered and dried under vacuum at 60°C for 8 h to obtain isocyanated silica.

[0064] C3. Polyethylene glycol grafting: 470 parts of isocyanate-modified silica and 1050 parts of anhydrous toluene were added to a reaction vessel and stirred and dispersed at 67°C for 45 min; 155 parts of polyethylene glycol 2000 (hydroxyl value 56 mg KOH / g) were added dropwise, and after the addition was completed, the temperature was raised to 77°C and reacted for 4 h; purified with a dialysis bag with a molecular weight cutoff of 10000, and freeze-dried at -40°C for 24 h to obtain composite silica A.

[0065] The particle size of composite silica A is 25 nm, and the grafting density of polyethylene glycol 2000 is 1.8 chains / nm. 2 The specific surface area of ​​composite silica A is 145 m². 2 / g.

[0066] The preparation of composite silica B includes the following steps: D1. Isocyanate treatment: 620 parts of fumed silica and 1900 parts of anhydrous xylene were added to a reaction vessel and stirred and dispersed at 87°C for 1 h under nitrogen protection; 37 parts of 3-propyltriethoxysilane were added dropwise, and after the addition was complete, the temperature was raised to 92°C and reacted for 5 h; after filtration, the mixture was washed 3 times with anhydrous xylene and dried under vacuum at 70°C for 10 h to obtain isocyanate silica.

[0067] D2. Polycaprolactone grafting: 570 parts of isocyanate-modified silica and 1600 parts of anhydrous xylene were added to a reaction vessel and stirred and dispersed at 92℃ for 40 min; 125 parts of PCL800-OH (hydroxyl value 142 mg KOH / g) were added dropwise, and after the addition was complete, 0.85 parts of dibutyltin dilaurate were added, and the reaction was carried out at 102℃ for 3 h; the temperature was lowered to 62℃ and 4.2 parts of benzoyl chloride were added to terminate the reaction, and the silica was purified by precipitation with anhydrous ethanol and dried under vacuum at 50℃ for 12 h to obtain polycaprolactone grafted silica.

[0068] D3. Surface modification: 520 parts of polycaprolactone-grafted silica and 1050 parts of anhydrous tetrahydrofuran were added to the reactor and stirred at 42°C for 30 min; 5.5 parts of 3-propyltriethoxysilane were added dropwise and reacted at 52°C for 2 h; the solvent was removed by rotary evaporation and dried under vacuum at 60°C for 8 h to obtain composite silica B.

[0069] The composite silica B has a particle size of 30 nm, a PCL800-OH grafting density of 1.2 chains / nm², and a hydroxyl value of 42 mgKOH / g.

[0070] A method for preparing a high-performance polyurethane elastomer composite material resistant to media erosion includes the following steps: S1. Raw material pretreatment; Polycarbonate diol (345 parts): Add to a vacuum dehydration kettle, dehydrate under vacuum at 122℃ and 200Pa for 2 hours, and cool to 80℃ for later use; Polytetrahydrofurandiol (150 parts): Add to a vacuum dehydration kettle and dehydrate under vacuum at 112℃ and 200Pa for 2 hours. Cool to 80℃ for later use. Diphenylmethane diisocyanate (325 parts): Add to a melting vessel, heat to 67°C to melt, filter through a 0.5μm filter membrane, purge with nitrogen for protection, and keep at 62°C for later use; Polyamide-amine dendritic polymer (6 parts): Mixed with N,N-dimethylformamide (24 parts), stirred until completely dissolved, to prepare a 20% concentration solution, and dried under vacuum at 82℃ and 100Pa for 4 hours for later use; Composite silica A (7.5 parts): Add to a vacuum drying oven and dry at 82℃ and 100Pa for 2 hours for later use; Composite silica B (10 parts): Add to a vacuum drying oven and dry at 72℃ and 100Pa for 2 hours for later use.

[0071] S2, Preparation of pre-dispersion system; 1. High polarity pre-dispersion: Add composite silica A (7.5 parts) to a high-speed disperser, add the above dendritic polymer / N,N-dimethylformamide solution (30 parts), disperse at 1550 rpm for 15 min, then transfer to a 20 kHz ultrasonic device for 10 min, and store at 40℃ under nitrogen protection. 2. Low polarity pre-dispersion: Take polycarbonate diol (345 parts) and polytetrahydrofuran diol (150 parts) and add them to the premixing vessel. Heat to 112°C and add composite silica B (10 parts). Stir and premix at 320 rpm for 20 min. Then degas under vacuum at 100 Pa for 10 min and keep warm at 80°C for later use.

[0072] S3, polymerization reaction; 1. Synthesis of prepolymer: The low polarity predispersant was transferred into a reactor and dehydrated under vacuum at 112°C and 100Pa for 30 min to remove trace amounts of water from the system. After cooling to 77°C, diphenylmethane diisocyanate (325 parts) was added dropwise at a uniform rate. After the addition was complete, the temperature was raised to 87°C and reacted for 2 h to obtain the terminal isocyanate group prepolymer.

[0073] 2. Construction of the stable region: The isocyanate-terminated prepolymer was cooled to 80°C, and carbodiimide (12 parts) was added and kept at the temperature for 25 min to ensure uniform dispersion. Then the temperature was raised to 92°C, and a high polarity pre-dispersion was added dropwise at a rate of 0.5 parts / min. After the addition was completed, the reaction was carried out at 91°C for 1.3 h to construct a stable region at the hard segment-soft segment interface. At this time, the material is a prepolymer system containing the stable region.

[0074] 3. Chain extension reaction: The prepolymer system containing the stable region was cooled to 77°C. 1,4-Butanediol (52 parts) and organic bismuth catalyst (0.25 parts) were mixed and quickly added to the reactor. The mixture was stirred at 850 rpm for 5 min to ensure uniform mixing. The reaction was carried out at 87°C for 45 min to allow the molecular chains to grow fully and obtain the high molecular weight polyurethane primary product.

[0075] 4. Stabilization treatment: Cool the primary polyurethane product to 67°C, add antioxidant 1010 (3.5 parts) and light stabilizer UV-326 (2.5 parts), stir at 210 rpm for 15 min to disperse it evenly, remove N,N-dimethylformamide solvent under vacuum of 200 Pa for 30 min to obtain a uniform and stable polyurethane melt, and keep it at 62°C.

[0076] S4, Post-processing.

[0077] 1. Extrusion Granulation: The polyurethane melt, which was kept warm in step S3, is conveyed to a parallel twin-screw extruder through a 62℃ insulated pipeline. The temperatures of each section are set as follows: feed section 87℃, compression section 112℃, melting section 137℃, metering section 150℃, and die head 144℃; the screw speed is 220 rpm, the feed speed is 58 rpm, and the melt index is controlled at 9.5 g / 10 min. After the material is extruded through a Φ3mm die, it is cut into cylindrical granules with a particle size of 3.1 mm and a length of 3.7 mm; the granules are dehydrated in a centrifugal dewatering machine (820 rpm) for 10 min and then dried with hot air at 60℃ for 1 h.

[0078] 2. Vacuum drying: Transfer the hot air dried particles into a vacuum drying oven and dry them at 62℃ and 100Pa for 16 hours to thoroughly remove residual moisture from the interior.

[0079] 3. Step-by-step maturation: The vacuum-dried granules are placed in a forced-air drying oven and first matured at 62℃ for 22 hours to promote the initial regular arrangement of molecular chains. Then, the temperature is increased to 81℃ at a rate of 1.2℃ / min and held for 45 hours to make the microphase structure more perfect. Finally, after cooling to room temperature, the product is packaged to obtain the finished product.

[0080] Comparative Example 1 The difference from Example 1 is that it does not contain composite silica A, but the remaining components, dosages, and preparation methods are completely consistent with Example 1.

[0081] Comparative Example 2 The difference from Example 1 is that it does not contain composite silica B, but the remaining components, dosages, and preparation methods are completely consistent with Example 1.

[0082] Comparative Example 3 The difference from Example 1 is that ordinary fumed silica (ungrafted, 20nm particle size, 200m² / g specific surface area) is used to replace composite silica A and B, while the remaining components, dosages, and preparation methods are completely consistent with Example 1.

[0083] Comparative Example 4 The difference from Example 1 is that it does not contain third-generation polyamide-amine dendritic polymers, and N,N-dimethylformamide is directly added to the system as a solvent. The remaining components, dosages, and preparation methods are completely consistent with those in Example 1.

[0084] test 1. Comparison Test of Media Resistance a. Oil resistance test: Sample preparation: Polyurethane elastomer particles (finished products) from Examples 1-3 and Comparative Examples 1-4 were processed into dumbbell-shaped Type I samples (compliant with GB / T528-2009 standard) using an injection molding machine. Injection molding parameters: barrel temperature 140-145℃, mold temperature 60℃, injection pressure 80MPa, holding pressure 60MPa, cooling time 30s; sample thickness was controlled at 2.0±0.2mm, and the surface was free of defects such as bubbles and cracks.

[0085] Test Procedure: The prepared samples were conditioned for 48 hours in a standard laboratory environment at 23±2℃ and 50±5%RH. The initial tensile strength and elongation at break were tested using an electronic tensile testing machine according to GB / T528-2009 standard. Subsequently, the samples were completely immersed in aviation kerosene (compliant with GB6537-2018) and 0# diesel oil (compliant with GB19147-2016), respectively, and placed in a constant temperature oven at 70±2℃ for 168 hours. After immersion, the samples were removed, and the residual medium on the surface was blotted dry with dust-free filter paper. They were then left at room temperature for 30 minutes, and then conditioned for 24 hours in a standard laboratory environment before the tensile strength and elongation at break were retested.

[0086] Evaluation criteria: Performance retention rate (%) = (Performance after immersion / Initial performance) × 100%.

[0087] The data is shown in Table 1.

[0088] Table 1

[0089] b. Hydrolysis resistance test: Sample preparation: Polyurethane elastomer granules (finished products) from Examples 1-3 and Comparative Examples 1-4 were processed into dumbbell-shaped Type I samples (compliant with GB / T528-2009 standard) using an injection molding machine. Injection molding parameters: barrel temperature 140-145℃, mold temperature 60℃, injection pressure 80MPa, holding pressure 60MPa, cooling time 30s; the sample thickness was controlled to be 2.0±0.2mm, and the surface was free of defects such as bubbles and cracks. Five parallel samples were prepared for each group.

[0090] Test Procedure: The prepared samples were conditioned for 48 hours in a standard laboratory environment at 23±2℃ and 50±5%RH. The initial tensile strength and elongation at break were tested using a 0.5-grade electronic tensile testing machine according to GB / T528-2009 standard. Subsequently, the samples were suspended in a constant temperature and humidity chamber, with environmental conditions set at 70℃ and 95%RH, and sealed for 168 hours of aging. After aging, the samples were removed and conditioned for 24 hours in a standard laboratory environment, and the tensile strength and elongation at break were retested.

[0091] Evaluation criteria: Performance retention rate (%) = (Performance after aging / Initial performance) × 100%.

[0092] The data is shown in Table 2.

[0093] Table 2

[0094] c. Chemical resistance test Sample preparation: Polyurethane elastomer granules (finished products) from Examples 1-3 and Comparative Examples 1-4 were processed into dumbbell-shaped Type I samples using an injection molding machine (compliant with GB / T528-2009 and GB / T2567-2021 standards). Injection molding parameters: barrel temperature 140-145℃, mold temperature 60℃, injection pressure 80MPa, holding pressure 60MPa, cooling time 30s; sample thickness was controlled to be 2.0±0.2mm, and the surface was free of scratches, impurities, and bubble defects. Five parallel samples were prepared for each group.

[0095] Test procedure: The prepared samples were conditioned for 48 hours in a standard laboratory environment of 23±2℃ and 50±5%RH; the initial tensile strength and elongation at break were tested using a 0.5 grade electronic tensile testing machine according to GB / T528-2009 standard; the samples were completely immersed in hydrochloric acid solution with pH=3 and sodium hydroxide solution with pH=11 respectively, and soaked in a constant temperature oven at 70±2℃ for 168 hours; after soaking, the samples were removed, rinsed 3 times with deionized water, and drained at room temperature for 30 minutes; after conditioning for 24 hours in a standard laboratory environment, the tensile strength and elongation at break were retested.

[0096] Evaluation criteria: Performance retention rate (%) = (Performance after immersion / Initial performance) × 100%.

[0097] The data is shown in Table 3.

[0098] Table 3

[0099] As shown in Table 1, after immersion in aviation kerosene and #0 diesel for 168 hours, the tensile strength and elongation at break retention rates of the samples in Examples 1-3 were significantly higher than those of Comparative Examples 1-4. The tensile strength retention rate of Examples 1-3 in aviation kerosene reached 90.8%-93.6%, and the elongation at break retention rate reached 88.2%-91.2%; in #0 diesel, the tensile strength retention rate reached 89.1%-92.0%, and the elongation at break retention rate reached 86.4%-89.5%. In contrast, the corresponding performance retention rates of Comparative Examples 1-4 were significantly lower, especially that of Comparative Example 4 (without dendritic polymer), which had the lowest retention rates of only 59.4% and 57.2%, respectively. This indicates that the "hard segment-stable region-soft segment" three-phase microstructure constructed in this invention, along with the synergistic effect of composite silica A and B and dendritic polymer, effectively improves the stability of the material in an oil-based environment.

[0100] As shown in Table 2, after aging for 168 hours at 70℃ and 95%RH high humidity and heat, the tensile strength retention rate of samples in Examples 1-3 was 91.8%-94.7%, and the elongation at break retention rate was 88.7%-92.1%, significantly better than that of Comparative Examples 1-4 (tensile strength retention rate 61.2%-81.3%, elongation at break retention rate 57.4%-77.5%). In particular, Comparative Example 4 (without dendritic polymer) showed the most severe performance degradation, indicating that the stable region formed by the polyamide-amine dendritic polymer at the hard / soft segment interface plays a key role in the hydrolysis resistance of this material, effectively preventing water molecules from attacking the polyurethane backbone.

[0101] As shown in Table 3, after immersion in acidic and alkaline media (pH=3HCl and pH=11NaOH) for 168 hours, the samples of Examples 1-3 exhibited excellent chemical corrosion resistance. In acidic environments, the tensile strength retention rate reached 86.9%-89.8%, and the elongation at break retention rate reached 83.5%-87.3%; in alkaline environments, the tensile strength retention rate reached 85.8%-88.6%, and the elongation at break retention rate reached 82.7%-86.1%. In contrast, the performance retention rates of Comparative Examples 1-4 were significantly lower under the same conditions, especially Comparative Example 4 (without dendritic polymer) which had the lowest performance retention rate. This indicates that the three-phase microstructure and polar gradient distribution of the present invention effectively enhance the material's resistance to acid and alkaline corrosion.

[0102] 2. Additive precipitation test Sample preparation: Polyurethane elastomer particles (finished products) from Examples 1-3 and Comparative Examples 1-4 were processed into 10mm×10mm×2mm square samples (compliant with GB / T1690-2010 standard) using an injection molding machine. Injection molding parameters: barrel temperature 140-145℃, mold temperature 60℃, injection pressure 80MPa, holding pressure 60MPa, cooling time 30s; the sample thickness error was controlled within ±0.1mm, the surface was flat, and there were no bubbles or missing material defects. Five parallel samples were prepared for each group.

[0103] Test Procedure: The prepared sample was dried in a 60℃ vacuum drying oven for 24 hours. It was then accurately weighed using an analytical balance with an accuracy of 0.1 mg and the initial mass (m0) was recorded. The sample was completely immersed in 200 mL of distilled water with a resistivity ≥18.2 MΩ·cm and placed in a 50±0.5℃ constant temperature water bath for 7 days (168 hours), without changing the soaking solution. After soaking, the sample was removed, rinsed quickly three times with deionized water, and dried again under vacuum at 60℃ for 24 hours. The final mass (m1) was then recorded. All samples were collected. The soaking solution was centrifuged at 4000 r / min for 10 min to remove impurities, and the supernatant was filtered through a 0.45 μm organic phase filter membrane. The concentrations of antioxidant 1010 and UV-326 in the soaking solution were determined by HPLC. The chromatographic conditions were as follows: C18 reversed-phase column (250 mm × 4.6 mm, 5 μm), mobile phase methanol-water (85:15, v / v), flow rate 1.0 mL / min, column temperature 30 ℃, detection wavelength 280 nm (antioxidant 1010) and 340 nm (UV-326), and injection volume 10 μL.

[0104] Evaluation criteria: Additive precipitation (mg / g) = total mass of additives in the soaking solution / initial mass of sample; mass loss rate (%) = [(m0-m1) / m0]×100%, where m0 is the initial mass of the sample after vacuum drying, and m1 is the final mass after soaking, rinsing and vacuum drying again.

[0105] The data is shown in Table 4.

[0106] Table 4

[0107] As shown in Table 4, after soaking in a 50℃ water environment for 168 hours, the amount of additives precipitated and the mass loss rate of the samples in Examples 1-3 were significantly lower than those in Comparative Examples 1-4. In Examples 1-3, the amount of antioxidant 1010 precipitated was only 17.1-19.5 mg / g, and the amount of UV-326 precipitated was 15.4-17.8 mg / g, with a mass loss rate of 0.39%-0.45%; while in Comparative Examples 1-4, especially Comparative Example 4 (without dendritic polymer), the amount of precipitated polymers was as high as 86.5 mg / g and 79.2 mg / g, respectively, with a mass loss rate of 2.15%. This proves that the three-dimensional cavity structure of the polyamide-amine dendritic polymer in this invention can effectively lock in the additive molecules, preventing their migration and precipitation during long-term use, thereby maintaining the long-term stability of the material.

[0108] 3. Mechanical property retention test (thermal aging) Sample preparation: Polyurethane elastomer particles (finished products) from Examples 1-3 and Comparative Examples 1-4 were processed into dumbbell-shaped Type I samples using an injection molding machine (compliant with GB / T3512-2014 and GB / T528-2009 standards). Injection molding parameters: barrel temperature 140-145℃, mold temperature 60℃, injection pressure 80MPa, holding pressure 60MPa, cooling time 30s; the sample thickness was controlled to be 2.0±0.2mm, and the surface was free of bubbles, cracks and material shortages. Five parallel samples were prepared for each group at each time point.

[0109] Test procedure: The specimens were conditioned for 48 hours in a standard laboratory environment at 23±2℃ and 50±5%RH; the initial tensile strength and elongation at break were tested using a 0.5 grade electronic tensile testing machine according to GB / T528-2009 standard; the specimens were suspended in a forced ventilation thermal aging test chamber at 80±1℃ for continuous aging; the corresponding specimens were taken out at four time points: 168h, 336h, 504h, and 720h, and after conditioning for 24 hours in a standard laboratory environment, the tensile strength and elongation at break were retested.

[0110] Evaluation criteria: Performance retention rate (%) = (Performance after aging / Initial performance) × 100%.

[0111] The data on tensile strength retention rate are shown in Table 5 and the data on elongation at break retention rate are shown in Table 6.

[0112] Table 5

[0113] Table 6

[0114] As shown in Tables 5 and 6, under the thermal aging environment of 80℃, the mechanical property retention rate of the samples in Examples 1-3 decreased slowly over time, with the tensile strength retention rate still as high as 87.4%-90.8% and the elongation at break retention rate reaching 84.9%-89.7% after 720 hours. In contrast, the performance degradation of Comparative Examples 1-4 was significantly accelerated, with the tensile strength retention rate only 42.6%-72.4% and the elongation at break retention rate only 38.2%-68.9% after 720 hours. This indicates that the "hard segment-stable region-soft segment" three-phase microstructure constructed in this invention and the polar gradient distribution formed by composite silica A and composite silica B significantly improve the thermal stability of the material and effectively delay the performance degradation during thermal aging.

[0115] In summary, the high-performance polyurethane elastomer composite material resistant to media erosion of the present invention constructs a three-phase microstructure of "hard segment-stable region-soft segment" and utilizes the polarity difference between composite silica A and B to form a guiding mechanism, so that the polyamide-amine dendritic polymer is precisely positioned in the interface region, effectively solving the technical problems of rapid mechanical property decay and easy precipitation of additives in traditional polyurethane under harsh media environments.

[0116] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high-performance polyurethane elastomer composite material resistant to media erosion, characterized in that, The product comprises the following raw materials: 4.5-7.5 parts of composite silica A, 6.0-10.0 parts of composite silica B, 315-325 parts of diphenylmethane diisocyanate, 340-345 parts of polycarbonate diol, 145-150 parts of polytetrahydrofuran diol, 4.5-6.0 parts of polyamide-amine dendritic polymer, 48-52 parts of 1,4-butanediol, 0.15-0.25 parts of organic bismuth catalyst, and 12-18 parts of additives. The composite silica A is PEG2000 grafted modified nano silica; The composite silica B is PCL800-OH grafted modified nano silica; The polyamide-amine dendritic polymer is a third-generation polyamide-amine dendritic polymer; The additives include 8-12 parts of hydrolysis stabilizer, 2.5-3.5 parts of antioxidant, and 1.5-2.5 parts of light stabilizer; The method for preparing the high-performance polyurethane elastomer composite material resistant to media erosion is characterized by comprising the following steps: S1. Vacuum dehydrate polycarbonate diol and polytetrahydrofuran diol, melt filter diphenylmethane diisocyanate, dissolve polyamide-amine dendritic polymer in N,N-dimethylformamide to prepare a solution, and vacuum dry composite silica A and composite silica B. S2. A high-polarity pre-dispersion was prepared by high-speed dispersion and ultrasonic treatment of composite silica A and polyamide-amine dendritic polymer solution. A low-polarity pre-dispersion was prepared by heating and premixing composite silica B with polycarbonate diol and polytetrahydrofuran diol. S3. First, react the low polarity predispersant with diphenylmethane diisocyanate to synthesize a prepolymer. Then, add a hydrolysis stabilizer and dropwise add a high polarity predispersant to construct a stable region. Subsequently, add 1,4-butanediol and an organic bismuth catalyst to carry out a chain extension reaction. Finally, add an antioxidant and a light stabilizer to complete the stabilization treatment and remove the solvent. S4. The finished product is obtained by extrusion granulation, vacuum drying and curing.

2. The high-performance polyurethane elastomer composite material resistant to media erosion according to claim 1, characterized in that, The composite silica A has a particle size of 15-25 nm, and the grafting density of PEG2000 is 1.2-1.8 chains / nm. 2 .

3. The high-performance polyurethane elastomer composite material resistant to media erosion according to claim 1, characterized in that, The composite silica B has a particle size of 20-30 nm and a PCL800-OH grafting density of 0.8-1.2 chains / nm. 2 .

4. The high-performance polyurethane elastomer composite material resistant to media erosion according to claim 1, characterized in that, The hydrolysis stabilizer is carbodiimide, the antioxidant is antioxidant 1010, and the light stabilizer is UV-326.

5. The method for preparing the high-performance polyurethane elastomer composite material resistant to media erosion according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Vacuum dehydrate polycarbonate diol and polytetrahydrofuran diol, melt filter diphenylmethane diisocyanate, dissolve polyamide-amine dendritic polymer in N,N-dimethylformamide to prepare a solution, and vacuum dry composite silica A and composite silica B. S2. A high-polarity pre-dispersion was prepared by high-speed dispersion and ultrasonic treatment of composite silica A and polyamide-amine dendritic polymer solution. A low-polarity pre-dispersion was prepared by heating and premixing composite silica B with polycarbonate diol and polytetrahydrofuran diol. S3. First, react the low polarity predispersant with diphenylmethane diisocyanate to synthesize a prepolymer. Then, add a hydrolysis stabilizer and dropwise add a high polarity predispersant to construct a stable region. Subsequently, add 1,4-butanediol and an organic bismuth catalyst to carry out a chain extension reaction. Finally, add an antioxidant and a light stabilizer to complete the stabilization treatment and remove the solvent. S4. The finished product is obtained by extrusion granulation, vacuum drying and curing.

6. The method for preparing a high-performance polyurethane elastomer composite material resistant to media erosion according to claim 5, characterized in that, In step S3, before adding the highly polar predispersant, the temperature of the reaction system is controlled at 75-80℃ and kept at that temperature for 25-35 minutes; then the temperature is raised to 88-92℃, and the highly polar predispersant is added to the prepolymer at a dropping rate of 0.40-0.50 parts / minute. After the addition is complete, the reaction is carried out at 90±1℃ for 1.3-1.7 hours.

7. The method for preparing a high-performance polyurethane elastomer composite material resistant to media erosion according to claim 5, characterized in that, In step S4, the curing process adopts a stepped heating method, first curing at 60±2℃ for 22-26 hours, and then heating to 80±1℃ at a heating rate of 0.8-1.2℃ / min and holding at that temperature for 45-49 hours.

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