Polyurethane composition, process for its preparation and use in pet strollers

Abstract

The application discloses a polyurethane composition, a preparation method thereof and application of the polyurethane composition in a pet stroller, and belongs to the technical field of polymer compound compositions, and the polyurethane composition comprises the following raw materials in parts by weight: 50-90 parts of polytetrahydrofuran ether glycol, 40-80 parts of butyl acetate, 30-55 parts of hexamethylene diisocyanate, 0.1-0.5 parts of an antioxidant, 0.05-0.15 parts of bismuth neodecanoate, 5-10 parts of 1,4-butanediol, 5-15 parts of nano silicon dioxide, 5-10 parts of flexible porous carbon nanofiber, 0.5-3 parts of a leveling agent and 0.5-1 part of a defoaming agent; compared with the prior art, the polyurethane composition is reasonable in formula design, good in compatibility of components, stable and controllable in preparation process, suitable for industrial production, and the comprehensive performance of the composition after curing meets the requirements of durability and functionality of materials in high-wear scenarios such as pet strollers.

Description

Technical Field

[0001] This invention relates to the field of polymer composition technology, and more particularly to a polyurethane composition, its preparation method, and its application in pet strollers. Background Technology

[0002] Polyurethane compositions are a class of functional material systems based on polyurethane prepolymers, formulated by adding fillers, additives, and other components. After curing, they possess the properties of both elastomers and plastics, and are widely used to prepare products with waterproof, breathable, and wear-resistant functions. By optimizing the formulation of polyurethane compositions, the mechanical properties, surface characteristics, and durability of the final products can be controlled.

[0003] In existing technologies, porous fillers or hydrophobic modifiers are often added to improve the breathability and waterproofness of polyurethane compositions. For example, patent document CN120230401A discloses a highly waterproof and breathable polyurethane material that utilizes modified porous biochar to construct water vapor channels in the polyurethane matrix, while simultaneously enhancing hydrophobicity through fluorination. However, in this approach, the interfacial bonding between the porous biochar and the polyurethane matrix is ​​weak, and the filler is prone to debonding under repeated friction, resulting in a significant decrease in the wear resistance of the cured polyurethane layer.

[0004] Furthermore, to improve the wear resistance of polyurethane compositions, some technical solutions employ the addition of rigid inorganic fillers to increase surface hardness. However, the introduction of a single rigid filler often comes at the cost of material flexibility, easily leading to stress concentration and brittle cracking, and making it difficult to simultaneously meet the requirements of waterproofing and breathability. Patent document CN120923832A discloses a waterproof and breathable polyurethane composition that introduces siloxane-containing monomers into the prepolymer to enhance hydrophobicity, but it does not address the design of wear-resistant components, resulting in insufficient durability of the cured layer under high-wear conditions.

[0005] In summary, existing polyurethane compositions struggle to simultaneously achieve a synergistic improvement in high abrasion resistance, high water resistance, and good breathability. Therefore, how to design formulations that significantly enhance abrasion resistance while maintaining excellent breathability and water resistance is a pressing technical challenge in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention aims to provide a polyurethane composition, its preparation method, and its application in pet strollers.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A polyurethane composition comprising the following raw materials in parts by weight: 50-90 parts polytetrahydrofuran ether glycol, 40-80 parts butyl acetate, 30-55 parts hexamethylene diisocyanate, 0.1-0.5 parts antioxidant, 0.05-0.15 parts bismuth neodecanoate, 5-10 parts 1,4-butanediol, 5-15 parts nano silica, 5-10 parts flexible porous carbon nanofibers, 0.5-3 parts leveling agent, and 0.5-1 part defoamer; The flexible porous carbon nanofiber comprises the following raw materials in parts by weight: 0.5-2 parts polyacrylonitrile, 0.5-2 parts polyvinylpyrrolidone, 5-15 parts N,N-dimethylformamide, 0.2-0.6 parts organometallic precursor and 0.3-0.8 parts reinforcing phase; The organometallic precursor is composed of titanium acetylacetonate and ferrocene.

[0008] The leveling agent is at least one of Tego-270 and RM-2020.

[0009] The defoamer is an organosilicon defoamer, and the antioxidant is at least one of antioxidant 1010 and antioxidant 168.

[0010] The method for preparing the polyurethane composition includes the following steps: Weigh out polytetrahydrofuran ether diol and butyl acetate and mix them. Under nitrogen atmosphere, add hexamethylene diisocyanate, antioxidant and bismuth neodecanoate. Heat and stir. When the isocyanate group content of the reaction system drops to 70-80% of the initial NCO0, add 1,4-butanediol and continue the reaction. Add nano silica mixture, flexible porous carbon nanofibers, leveling agent and defoamer and stir to disperse to obtain the polyurethane composition.

[0011] The preparation method of the flexible porous carbon nanofibers is as follows: S1. Weigh polyacrylonitrile and polyvinylpyrrolidone and add them to N,N-dimethylformamide. Stir to dissolve, then add organometallic precursor and reinforcing phase, sonicate, and then heat and stir to form spinning solution. S2. Electrospin the spinning solution obtained in step S1 to obtain a composite nanofiber nonwoven membrane. S3. The composite nanofiber nonwoven membrane obtained in step S2 is pre-oxidized, then heated in a high-purity nitrogen atmosphere to complete carbonization, and cooled to room temperature to obtain flexible porous carbon nanofibers.

[0012] Preferably, the method for preparing the polyurethane composition includes the following steps: Polytetrahydrofuran ether glycol and butyl acetate were weighed and added to a dry reaction vessel. After purging the vessel with nitrogen to replace the air, hexamethylene diisocyanate, antioxidant, and bismuth neodecanoate were added. The mixture was heated to 50-80°C and stirred to carry out a prepolymerization reaction. The initial isocyanate group content of the reaction system was determined by di-n-butylamine titration and recorded as NCO0. The reaction was continued until the NCO value dropped to 70-80% of NCO0. Then, 1,4-butanediol was added and the reaction was continued at 40-60°C for 30-50 minutes to complete the chain extension. Nano-silica was pre-dispersed in butyl acetate and ultrasonically dispersed for 10-50 minutes at an ultrasonic power of 100-500W and a frequency of 20-60kHz to obtain a nano-silica mixture. The nano-silica mixture, flexible porous carbon nanofibers, leveling agent, and defoamer were added to the reaction vessel and stirred and dispersed for 10-50 minutes to obtain the polyurethane composition.

[0013] The preparation method of the flexible porous carbon nanofibers is as follows: S1. Weigh polyacrylonitrile and polyvinylpyrrolidone and add them to N,N-dimethylformamide. Stir to dissolve, then add organometallic precursor and reinforcing phase, sonicate, and then heat and stir to form spinning solution. S2. Electrospin the spinning solution obtained in step S1 to obtain a composite nanofiber nonwoven membrane. S3. The composite nanofiber nonwoven membrane obtained in step S2 is pre-oxidized, then heated in a high-purity nitrogen atmosphere to complete carbonization, and cooled to room temperature to obtain flexible porous carbon nanofibers.

[0014] Preferably, the flexible porous carbon nanofibers are prepared as follows: S1. Weigh polyacrylonitrile and polyvinylpyrrolidone and add them to N,N-dimethylformamide. Stir continuously at 40-60℃ for 5-20h until completely dissolved. Then add organometallic precursor and reinforcing phase. Place the mixture in a closed ultrasonic disperser and sonicate at 30-50℃ for 1-3h. Then raise the temperature to 50-70℃ and stir continuously for 2-6h to form spinning solution. S2. Transfer the spinning solution obtained in step S1 to an 8-15mL plastic syringe, use a stainless steel needle for electrospinning, set a positive high voltage of 12-16kV, a negative high voltage of -1.5~-2kV, a receiving distance of 12-20cm, a roller collector rotation speed of 80-150r / min, a injection rate of 0.1-0.5mm / min, an ambient temperature of 20-25℃, and a relative humidity of 40-60%, and continuously collect to obtain a composite nanofiber nonwoven membrane with a thickness of 50-150μm; S3. Place the composite nanofiber nonwoven membrane obtained in step S2 in a tube furnace and heat it from room temperature to 200-250℃ at a heating rate of 1-5℃ / min in an air atmosphere and keep it at a constant temperature for 2-6 hours to complete the pre-oxidation. Then switch to a high-purity nitrogen atmosphere with a gas flow rate of 200-300mL / min and continue heating to 850-1000℃ at a heating rate of 1-5℃ / min and keep it at a constant temperature for 1-10 hours to complete the carbonization. After naturally cooling to room temperature, flexible porous carbon nanofibers are obtained.

[0015] The organometallic precursor is at least one of titanium acetylacetonate, molybdenum acetylacetonate, hafnium acetylacetonate, ferrocene, and zirconium acetylacetonate.

[0016] Preferably, the organometallic precursor is composed of titanium acetylacetonate and ferrocene.

[0017] More preferably, the organometallic precursor is composed of titanium oxyacetylacetonate and ferrocene in a mass ratio of 0.5-2:0.5-2.

[0018] The reinforcing phase is at least one of nano-alumina and nano-hexagonal boron nitride.

[0019] Preferably, the reinforcing phase is composed of nano-alumina and nano-hexagonal boron nitride in a mass ratio of 2-4:1-3.

[0020] The polyurethane composition is applied to a pet stroller in the following manner: the polyurethane composition is scraped onto the surface of release paper, dried to form a polyurethane material, which is then sequentially laminated with a TPU hot melt adhesive film and polyester Oxford cloth, and hot-pressed to obtain a wear-resistant, waterproof and breathable composite fabric for a pet stroller.

[0021] The drying process involves pre-drying at 60-90℃ for 5-15 minutes, followed by main drying at 80-98℃ for 5-30 minutes, and finally post-drying at 100-120℃ for 5-10 minutes.

[0022] The hot-pressing composite is performed at a temperature of 110-140℃ and a pressure of 0.3-0.8MPa for 10-30 seconds.

[0023] The gap between the scrapers is 50-100 μm.

[0024] While existing waterproof and breathable polyurethane materials have made some progress in terms of moisture permeability and waterproofing, their abrasion resistance is generally insufficient. This is especially true in high-wear, high-frequency use scenarios like pet strollers, where polyurethane materials are easily damaged by friction, pilling, and even exposing the base fabric, leading to a loss of waterproofing. Furthermore, while porous fillers introduced in existing technologies help with moisture permeability, they often have weak interfacial bonding with the polyurethane matrix and are easily pulled out during friction, further accelerating wear. In addition, existing technologies generally neglect the synergistic design between the fabric's hydrophobicity and abrasion resistance, making it difficult to simultaneously meet the comprehensive requirements of pet strollers for high abrasion resistance, high waterproofing, and good breathability. Therefore, how to significantly improve the abrasion resistance and waterproof durability of polyurethane materials while maintaining good breathability has become a pressing technical problem to be solved in this field.

[0025] To address the aforementioned issues, this invention first introduces flexible porous carbon nanofibers as a reinforcing skeleton into polyurethane materials. It should be noted that the flexibility referred to here means that the three-dimensional porous network structure constructed by electrospinning exhibits excellent macroscopic bending compliance, effectively adapting to the deformation of the polyurethane matrix under stress or thermal expansion and contraction, thus preventing debonding between the fiber skeleton and the matrix interface. In the preparation of this flexible skeleton, this invention further adds an organometallic precursor (such as titanium oxyacetylacetonate), which, after electrospinning and high-temperature carbonization, generates high-hardness metal carbide nanoparticles (such as titanium carbide) in situ within and on the surface of the carbon nanofibers. These nanoparticles are dispersed in the fiber matrix in a dotted or island-like manner, rather than forming a continuous hard shell. This microstructural design achieves a synergistic effect between a flexible carbon network and rigid hard particles: the flexible porous carbon nanofiber network acts as a continuous skeleton, providing overall structural integrity, deformation adaptability, and stress dispersion channels, preventing stress concentration from leading to brittle fracture; while the in-situ generated dispersed hard particles act as nanoscale wear-resistant armor, bearing the cutting and ploughing of abrasives during friction, effectively protecting the carbon fiber body and polyurethane matrix. Therefore, this structure significantly improves the wear resistance of the fabric without sacrificing the flexibility of the carbon nanofiber network. Instead, the pinning effect of the hard particles inhibits excessive deformation and fatigue fracture of the fibers during repeated friction. However, while single metal carbides can provide hardness, their intrinsic toughness is insufficient. Under continuous high-load friction, microcracks may still form around the dispersed particles due to stress concentration, posing a risk of particle detachment and limiting further improvement in wear resistance.

[0026] To further overcome the limitations of a single hard phase, this invention combines titanium oxyacetylacetonate with ferrocene. The nano-iron and cementite particles generated during the carbonization process of ferrocene serve as heterogeneous nucleation sites, inducing heterogeneous nucleation of titanium carbide on its surface. This significantly refines the titanium carbide grains and inhibits agglomeration, promoting the regularization of the carbon skeleton structure and forming a denser, disordered graphite structure. The generated nano-iron and iron carbide particles act as interfacial bonding phases distributed around the hard titanium carbide particles, forming an interfacial transition layer and constructing a dual-phase reinforced structure where the hard phase bears the load and the interfacial phase optimizes force transmission. Furthermore, hexagonal boron nitride with a graphite-like layered structure is introduced. Under frictional shear force, it slides along the crystal plane to form a continuous lubricating film, significantly reducing the coefficient of friction. Simultaneously, its intrinsic hydrophobic properties optimize the fiber surface wetting behavior, forming a hard-slip synergy and a hydrophobic synergy with the titanium-iron hard phase. Ultimately, this significantly improves the wear resistance and waterproof performance of the polyurethane material, making it suitable as a high-wear-resistant, high-water-resistant, and well-breathable material for pet strollers.

[0027] Compared with the prior art, the present invention has the following beneficial technical effects: 1) This invention significantly improves the wear resistance of polyurethane materials by introducing flexible porous carbon nanofibers and generating a metal carbide hard reinforcing phase in situ.

[0028] 2) This invention utilizes the synergistic compounding of ferrocene and titanium acetylacetonate to form a dual-phase reinforced structure of hard and tough phases, avoiding brittle fracture of a single hard phase and further improving wear resistance.

[0029] 3) By introducing hexagonal boron nitride, this invention utilizes its layered slip lubrication and intrinsic hydrophobic properties to achieve a synergistic improvement in wear resistance and waterproofing, resulting in a polyurethane material with both high wear resistance and high waterproofing performance.

[0030] 4) The present invention utilizes the intrinsic micropores generated by the solvent evaporation during the coating and drying process of the polyurethane composition. These micropores are interconnected with the abundant open-pore structure of the flexible porous carbon nanofibers dispersed therein, thus constructing microscopic channels inside the membrane that allow selective passage of air molecules. At the same time, the hydrophobic matrix of polyurethane is used to block liquid water, thereby achieving good air permeability while ensuring high waterproofness. Detailed Implementation

[0031] The sources or parameters of some substances are as follows: Polytetrahydrofuran ether diol: CAS number 25190-06-1, molecular weight 2000.

[0032] Hexamethylene diisocyanate: CAS number 822-06-0, is an aliphatic diisocyanate with a purity ≥99%.

[0033] Bismuth neodecanoate: CAS number 34364-26-6, is an organic bismuth catalyst with a bismuth content of 26%.

[0034] 1,4-Butanediol: CAS number 110-63-4, is a small molecule chain extender with a purity ≥99.5%.

[0035] Butyl acetate: CAS number 123-86-4, is an organic solvent for polyurethane, with a purity ≥99.5%.

[0036] Nano-silica: CAS number 112945-52-5, is hydrophilic fumed nano-silica with an average native particle size of 7-40 nm and a specific surface area (BET) of 200 m². 2 / g, purity 99.8%.

[0037] TPU hot melt adhesive film: It is a thermoplastic polyurethane hot melt adhesive film with a thickness of 10μm and a hot pressing temperature of 120-150℃.

[0038] Polyester Oxford cloth: Woven Oxford cloth made of 300D polyester filament, with a density of approximately 18×18 threads / inch and a weight of 120-150g / m². 2 .

[0039] Leveling agent, Dow Chemical, model: RM-2020.

[0040] Silicone defoamer, BYK-066N, manufactured by BYK Chemicals, Germany.

[0041] Polyacrylonitrile: CAS number 25014-41-9, average molecular weight 100,000.

[0042] Polyvinylpyrrolidone: CAS number 9003-39-8, average molecular weight 55000.

[0043] Acetylacetone titanium oxide: CAS number 14024-64-7, purity ≥98%.

[0044] Molybdenum acetylacetonate: CAS number 17524-05-9, purity 97-99%.

[0045] Hafnium acetylacetonate: CAS number 17475-67-1, purity ≥97%.

[0046] Ferrocene: CAS number 102-54-5, purity ≥98%.

[0047] Zirconium acetylacetonate: CAS number 17501-44-9, purity 97-99.9%.

[0048] Vanadyl acetylacetonate: CAS number 3153-26-2, purity ≥99%.

[0049] Nano-alumina: CAS number 1344-28-1, α-Al2O3 crystal form, average particle size 30-100nm, purity ≥99.9%.

[0050] Nano-hexagonal boron nitride: CAS number 10043-11-5, average particle size 100-500nm, purity ≥99.9%, with a layered graphite-like structure.

[0051] In the embodiments and comparative examples of this invention, all raw materials are commercially available products. Example 1

[0052] A method for preparing a polyurethane composition is as follows, in parts by weight: 70 parts of polytetrahydrofuran ether glycol and 45 parts of butyl acetate were weighed and added to a dry reaction vessel. After purging the vessel with nitrogen to replace the air, 45 parts of hexamethylene diisocyanate, 0.2 parts of antioxidant 1010 and 0.08 parts of bismuth neodecanoate were added. The mixture was heated to 70°C and stirred to carry out a prepolymerization reaction. The initial isocyanate group content of the reaction system was determined by di-n-butylamine titration and recorded as NCO0. The reaction was continued until the NCO value dropped to 75% of NCO0. Then, 8 parts of 1,4-butanediol were added and the reaction was continued at 50°C for 40 minutes to complete the chain extension. 10 parts of nano-silica were pre-dispersed in 15 parts of butyl acetate and ultrasonically dispersed for 30 minutes at an ultrasonic power of 300W and a frequency of 40kHz to obtain a nano-silica mixture. The nano-silica mixture, 8 parts of flexible porous carbon nanofibers, 1.5 parts of leveling agent and 0.8 parts of silicone defoamer were added to the reaction vessel and stirred and dispersed for 30 minutes to obtain a polyurethane composition.

[0053] The preparation method of the flexible porous carbon nanofibers is as follows, in parts by weight: S1. Weigh 1 part polyacrylonitrile and 1.2 parts polyvinylpyrrolidone and add them to 10 parts N,N-dimethylformamide. Stir continuously at 50°C for 12 hours until completely dissolved. Then add 0.4 parts organometallic precursor and 0.5 parts reinforcing phase. Place the mixture in a closed ultrasonic disperser and sonicate at 40°C for 1.5 hours. Then raise the temperature to 60°C and stir continuously for 4 hours to form a spinning solution. S2. Transfer the spinning solution obtained in step S1 to a 12mL plastic syringe, use a 20G stainless steel needle for electrospinning, set a positive high voltage of 14kV, a negative high voltage of -1.8kV, a receiving distance of 16cm, a roller collector speed of 120r / min, a injection rate of 0.2mm / min, an ambient temperature of 22℃, and a relative humidity of 50%, and continuously collect to obtain a composite nanofiber nonwoven membrane with a thickness of 100μm. S3. Place the composite nanofiber nonwoven membrane obtained in step S2 in a tube furnace and heat it from room temperature to 220°C at a heating rate of 2°C / min in an air atmosphere and keep it at the same temperature for 4 hours to complete the pre-oxidation. Then switch to a high-purity nitrogen atmosphere with a gas flow rate of 250 mL / min and continue heating to 900°C at a heating rate of 2.5°C / min and keep it at the same temperature for 5 hours to complete the carbonization. After naturally cooling to room temperature, flexible porous carbon nanofibers are obtained.

[0054] The organometallic precursor is titanium acetylacetonate.

[0055] The reinforcing phase is nano-alumina. Example 2

[0056] The preparation method of a polyurethane composition is basically the same as that in Example 1, except that the organometallic precursor in the preparation method of the flexible porous carbon nanofiber is molybdenum acetylacetonate. Example 3

[0057] The preparation method of a polyurethane composition is basically the same as that in Example 1, except that the organometallic precursor in the preparation method of the flexible porous carbon nanofiber is hafnium acetylacetonate. Example 4

[0058] The preparation method of a polyurethane composition is basically the same as that in Example 1, except that the organometallic precursor in the preparation method of the flexible porous carbon nanofiber is ferrocene. Example 5

[0059] The preparation method of a polyurethane composition is basically the same as that in Example 1, except that the organometallic precursor in the preparation method of the flexible porous carbon nanofiber is zirconium acetylacetonate. Example 6

[0060] The preparation method of a polyurethane composition is basically the same as that in Example 1, except that the organometallic precursor in the preparation method of the flexible porous carbon nanofiber is composed of titanium oxyacetylacetonate and ferrocene in a mass ratio of 1:1. Example 7

[0061] The preparation method of a polyurethane composition is basically the same as that in Example 1, except that the organometallic precursor in the preparation method of the flexible porous carbon nanofiber is composed of molybdenum acetylacetonate and hafnium acetylacetonate in a mass ratio of 1:1. Example 8

[0062] The preparation method of a polyurethane composition is basically the same as that in Example 6, except that the reinforcing phase in the preparation method of the flexible porous carbon nanofiber is composed of nano-alumina and nano-hexagonal boron nitride in a mass ratio of 3:2.

[0063] Comparative Example 1 The preparation method of a polyurethane composition is basically the same as that in Example 1, except that the organometallic precursor in the preparation method of the flexible porous carbon nanofiber is vanadium acetylacetonate.

[0064] Comparative Example 2 The preparation method of a polyurethane composition is basically the same as that in Example 1, except that the organometallic precursor is not added in the preparation method of the flexible porous carbon nanofiber.

[0065] Comparative Example 3 The preparation method of a polyurethane composition is basically the same as that in Example 1, except that the organometallic precursor and reinforcing phase are not added in the preparation method of the flexible porous carbon nanofibers.

[0066] Comparative Example 4 The preparation method of a polyurethane composition is basically the same as that in Example 1, except that the flexible porous carbon nanofibers are not added.

[0067] Application Example 1 The polyurethane compositions of each embodiment and comparative example were coated onto the surface of release paper using a doctor blade coating method, with the doctor blade gap controlled at 80 μm. The mixture was first pre-dried at 80°C for 8 minutes, then main-dried at 95°C for 15 minutes, and finally dried at 110°C for 8 minutes to obtain the polyurethane material. After peeling the material off the release paper, it was sequentially laminated with a TPU hot melt adhesive film and a polyester Oxford cloth. The lamination was hot-pressed at 120°C and 0.5 MPa for 20 seconds to obtain a wear-resistant, waterproof, and breathable composite fabric for pet strollers.

[0068] Test Example 1 Abrasion resistance test: The tests were conducted according to GB / T 21196.2-2007 "Textiles - Martindale Method: Determination of Abrasion Resistance of Fabrics - Part 2: Determination of Specimen Breakage". The composite fabric prepared in Application Example 1 was cut into circular specimens with a diameter of 140 mm. The polyurethane side of each circular specimen was tested on a Martindale abrasion tester. The abrasive was standard wool felt, the friction load was 12 kPa, and the specimens were rubbed back and forth along a Lissajous curve. The number of abrasion cycles corresponding to the appearance of significant wear (fiber breakage, pilling, or exposure of the base fabric) was recorded. Three parallel samples were tested for each specimen, and the arithmetic mean was taken as the number of abrasion cycles for that specimen. A higher value indicates better abrasion resistance. The test results are shown in Table 1.

[0069] Table 1 Experimental protocol Number of abrasion cycles Example 1 22487 Example 2 21763 Example 3 22156 Example 4 19512 Example 5 20984 Example 6 29635 Example 7 22121 Example 8 37248 Comparative Example 1 18237 Comparative Example 2 15816 Comparative Example 3 12394 Comparative Example 4 8623 Test Example 2 Waterproofing test The test was conducted according to GB / T 4744-2013, "Test and Evaluation of Waterproof Performance of Textiles - Hydrostatic Test". The composite fabric prepared in Application Example 1 was cut into circular specimens with a diameter of not less than 100 mm and placed in a hydrostatic tester. The effective test area of ​​the specimen was 100 cm². 2 The water pressure was increased uniformly at a rate of 60 cmH2O / min until a third seepage point appeared on the sample surface (polyester Oxford cloth layer). The hydrostatic pressure value at this point was recorded in millimeters of water column (mmH2O). Five parallel samples were tested for each sample, and the arithmetic mean was taken as the hydrostatic pressure resistance value of that sample. The higher the value, the better the waterproof performance. The relevant test data are summarized in Table 2.

[0070] Table 2 Experimental protocol <![CDATA[Hydrostatic pressure resistance value (mmH2O)]]> Example 1 16182 Example 2 15796 Example 3 16024 Example 4 15213 Example 5 15485 Example 6 16237 Example 7 15993 Example 8 18238 Comparative Example 1 15226 Comparative Example 2 15105 Comparative Example 3 14917 Comparative Example 4 13315 In Examples 1-5, the addition of organometallic precursors led to the reduction of metal ions during carbonization, which then combined with carbon to form high-hardness metal carbide nanoparticles. These particles were uniformly dispersed within the carbon nanofiber matrix, acting as a hard reinforcing phase to effectively resist the cutting and ploughing effects of abrasives on the fiber surface. Therefore, the wear resistance was significantly better than that of Comparative Example 2, which did not contain a metal precursor. In Example 1, the titanium carbide formed from the titanium source exhibited the highest intrinsic hardness, and its lattice parameters matched the carbon matrix well, resulting in high interfacial bonding strength and resistance to detachment during friction. Therefore, it demonstrated the best wear resistance among single metal sources.

[0071] Example 6, which combines titanium acetylacetonate with ferrocene, exhibits significantly better wear resistance than Examples 1-5, which use either precursor alone. This may be attributed to a synergistic effect between ferrocene and titanium acetylacetonate. During carbonization, the nano-iron and cementite particles formed by the decomposition of ferrocene act as heterogeneous nucleation sites, inducing heterogeneous nucleation of titanium carbide on its surface. This effectively refines the titanium carbide grain size and inhibits its agglomeration and growth. Simultaneously, it catalyzes the dehydrogenation cyclization and aromatization reactions of polyacrylonitrile, promoting the regularization of the carbon framework structure and forming a denser, disordered graphite structure. The generated nano-iron and iron carbide particles act as interfacial bonding phases distributed around the hard titanium carbide particles, forming an interfacial transition layer. This constructs a dual-phase reinforced structure where the hard phase bears the load and the interfacial phase optimizes force transmission, avoiding the brittle fracture of a single hard phase. In contrast, in Example 7, molybdenum acetylacetonate and hafnium acetylacetonate were carbonized to produce molybdenum carbide and hafnium carbide, respectively. Both are high-hardness carbides with overlapping and singular functions. They lack complementary mechanisms for catalytic nucleation and cannot form interface optimization and toughening synergy. They are merely simple physical mixtures of hard phases and therefore do not exhibit synergistic improvement effects.

[0072] Example 8 further introduces hexagonal boron nitride into the titanium-iron synergistic system of Example 6. This material has a graphite-like layered crystal structure. Under the action of frictional shear force, it slips along the crystal plane and forms a continuous lubricating film on the fiber surface, which significantly reduces the coefficient of friction and reduces the pull-out and breakage of hard carbides. At the same time, its intrinsic hydrophobic properties optimize the wetting behavior of the fiber surface, forming a hard-slip synergy and a hydrophobic synergy with the titanium-iron hard phase. Therefore, the wear resistance and waterproof performance are further improved.

Claims

1. A polyurethane composition, characterized in that, Including the following parts by weight of raw materials: 50-90 parts polytetrahydrofuran ether glycol, 40-80 parts butyl acetate, 30-55 parts hexamethylene diisocyanate, 0.1-0.5 parts antioxidant, 0.05-0.15 parts bismuth neodecanoate, 5-10 parts 1,4-butanediol, 5-15 parts nano silica, 5-10 parts flexible porous carbon nanofibers, 0.5-3 parts leveling agent, and 0.5-1 part defoamer; The flexible porous carbon nanofiber comprises the following raw materials in parts by weight: 0.5-2 parts polyacrylonitrile, 0.5-2 parts polyvinylpyrrolidone, 5-15 parts N,N-dimethylformamide, 0.2-0.6 parts organometallic precursor and 0.3-0.8 parts reinforcing phase; The organometallic precursor is composed of titanium acetylacetonate and ferrocene.

2. The polyurethane composition according to claim 1, characterized in that, The leveling agent is at least one of Tego-270 and RM-2020.

3. The polyurethane composition according to claim 1, characterized in that, The defoamer is an organosilicon defoamer, and the antioxidant is at least one of antioxidant 1010 and antioxidant 168.

4. A method for preparing a polyurethane composition according to any one of claims 1-3, characterized in that, Includes the following steps: Weigh out polytetrahydrofuran ether diol and butyl acetate and mix them. Under nitrogen atmosphere, add hexamethylene diisocyanate, antioxidant and bismuth neodecanoate. Heat and stir. When the isocyanate group content of the reaction system drops to 70-80% of the initial NCO0, add 1,4-butanediol and continue the reaction. Add nano silica mixture, flexible porous carbon nanofibers, leveling agent and defoamer and stir to disperse to obtain the polyurethane composition.

5. The method according to claim 4, characterized in that, The preparation method of the flexible porous carbon nanofibers is as follows: S1. Weigh polyacrylonitrile and polyvinylpyrrolidone and add them to N,N-dimethylformamide. Stir to dissolve, then add organometallic precursor and reinforcing phase, sonicate, and then heat and stir to form spinning solution. S2. Electrospin the spinning solution obtained in step S1 to obtain a composite nanofiber nonwoven membrane. S3. The composite nanofiber nonwoven membrane obtained in step S2 is pre-oxidized, then heated in a high-purity nitrogen atmosphere to complete carbonization, and cooled to room temperature to obtain flexible porous carbon nanofibers.

6. The method according to claim 5, characterized in that, The organometallic precursor is composed of titanium acetylacetonate and ferrocene in a mass ratio of 0.5-2:0.5-2.

7. The method according to claim 5, characterized in that, The reinforcing phase is at least one of nano-alumina and nano-hexagonal boron nitride.

8. The method according to claim 5, characterized in that, The reinforcing phase is composed of nano-alumina and nano-hexagonal boron nitride in a mass ratio of 2-4:1-3.

9. The use of the polyurethane composition according to any one of claims 1-3 in a pet stroller, characterized in that, The method is as follows: The polyurethane composition is scraped onto the surface of release paper, and after drying, a polyurethane material is formed. This material is then layered with a TPU hot melt adhesive film and a polyester Oxford cloth in sequence, and hot-pressed to obtain a wear-resistant, waterproof, and breathable composite fabric for pet strollers.

10. The application as described in claim 9, characterized in that, The drying process involves pre-drying at 60-90℃ for 5-15 minutes, followed by main drying at 80-98℃ for 5-30 minutes, and finally post-drying at 100-120℃ for 5-10 minutes. The hot-pressing process involves hot-pressing at 110-140℃ and 0.3-0.8MPa for 10-30 seconds.