Aqueous polyurethane fiber composite material and preparation method and application thereof

Abstract

The application discloses a kind of water-based polyurethane fiber composite material and its preparation method and application, belong to polymer composite material technical field.The material is by interface modified fiber base material and the multifunctional modified water-based polyurethane layer impregnated on its surface Composition.Said polyurethane is by polycarbonate dihydric alcohol, terminal hydroxyl polydimethylsiloxane, DOPO dihydric alcohol, dimethylol propionic acid and polyethylene glycol monomethyl ether etc. Functional unit is covalently bonded into molecular chain, is prepared water-based emulsion by pre-polymerization, hydrophilic chain extension, neutralization emulsification, chain extension in water and desolventization etc. Step.Fiber base material is treated by silane coupling agent and introduced active functional group, form chemical bonding interface with isocyanate group in polyurethane when curing.The application realizes water hydrolysis resistance, flexible, flame retardant, antistatic etc. Multifunctional integration, with interface bonding force is strong, environmental protection, process compatibility is good etc. Advantage, further expands in industrial textiles etc. Field.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and in particular to a waterborne polyurethane fiber composite material, its preparation method, and its application. Background Technology

[0002] Polyurethane (PU), a polymer material with a wide range of adjustable properties and excellent elasticity, has been widely used in textile coatings, adhesives, and composite materials. By compounding polyurethane with fiber substrates (such as polyester, nylon, aramid, and glass fiber) through coating or impregnation, fabrics can be endowed with waterproof, breathable, abrasion-resistant, weather-resistant, and other functional properties, thereby expanding its applications in high-value-added fields such as protective clothing, decorative fabrics, and industrial textiles. With increasingly stringent global environmental regulations and rising consumer demands for product safety, health, and sustainability, waterborne polyurethane (WPU), using water as the dispersion medium, is gradually replacing traditional solvent-based polyurethane, becoming an important direction for green chemistry and clean production.

[0003] However, existing waterborne polyurethane fiber composite materials still face a series of key technical bottlenecks in meeting the comprehensive, durable, and reliable requirements of the aforementioned high-end applications:

[0004] 1. Poor functional durability: It relies on physical blending or post-processing to add functional additives such as flame retardants and antistatic agents, which are prone to migration and precipitation under humid heat and friction, resulting in rapid performance degradation and damage to mechanical properties and feel.

[0005] 2. Weak interfacial bonding: The coating and fiber mainly rely on physical adsorption, which makes them prone to delamination and detachment under dynamic stress and damp heat aging, seriously affecting the durability and service life of the product.

[0006] 3. Difficulty in performance synergy: The requirements for multiple functions such as flame retardancy, antistatic properties, and weather resistance are mutually restrictive (e.g., flame retardant fillers impair flexibility, and hydrophilic components reduce water resistance), making it difficult to achieve efficient integration.

[0007] 4. Limitations of water-based systems: Compared with solvent-based systems, water-based systems are inferior in terms of film-forming properties, water resistance, mechanical strength, and drying efficiency, making it difficult to simultaneously improve high performance, multifunctionality, and high durability.

[0008] Therefore, developing a novel waterborne polyurethane fiber composite material that can achieve stable bonding of functional units from the molecular design stage, enhance overall reliability through strengthened interfacial bonding, and synergistically optimize multiple properties to meet the stringent requirements of protective clothing, high-end decorative fabrics, and industrial textiles has significant technological value and market potential. The corresponding preparation method should also be environmentally friendly, process-controllable, and suitable for large-scale production. This is precisely the core problem that this invention aims to solve. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of existing technologies by proposing a waterborne polyurethane fiber composite material, its preparation method, and its application.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] This invention provides a waterborne polyurethane fiber composite material, comprising fiber substrate pretreatment and a multifunctional modified waterborne polyurethane emulsion impregnated on its surface;

[0012] The specific method for pretreatment of the fiber substrate is as follows: KH-550 silane coupling agent is mixed with ethanol and deionized water at a volume ratio of 1:80:20, the pH is adjusted to 4-5 with acetic acid, and the substrate is hydrolyzed and activated for 25-35 minutes. The fiber substrate is then completely immersed in the treatment solution for 20-30 minutes. After removal, excess liquid is removed with rollers, and the substrate is dried at 80-100℃ for 8-12 minutes. Finally, it is cured at 110-120℃ for 15-25 minutes.

[0013] The multifunctional modified waterborne polyurethane is a waterborne polyurethane in which multifunctional structural units are covalently bonded to the main chain or side chains of its molecules through chemical synthesis. The preparation method of the multifunctional modified waterborne polyurethane emulsion is as follows:

[0014] Step 1. Synthesis of the prepolymer: Under dry nitrogen protection, polycarbonate diol (PCDL), hydroxyl-terminated polydimethylsiloxane (PDMS-OH), and DOPO diol (DOPO-HQ) were added sequentially to a four-necked flask. Stirring was started and the temperature was raised to 70-90℃ to ensure the polyol mixture was uniformly melted. Then, isophorone diisocyanate (IPDI) and catalyst DBTDL were added in 2-3 batches, and the reaction was maintained at 70-90℃ for 2-3 hours to obtain the NCO-terminated modified polyurethane prepolymer. The reaction process is as follows:

[0015] Step 2. Hydrophilic chain extension: Dissolve the hydrophilic chain extender dimethylolpropionic acid (DMPA) and polyethylene glycol monomethyl ether (MPEG) in 1-3 times the volume of acetone, and slowly add the solution dropwise to the prepolymer over 20-40 minutes using a constant pressure dropping funnel. After the addition is complete, continue the reaction at 70-80℃ for 1-2 hours to extend the chain and introduce hydrophilic groups and antistatic segments. The reaction process is as follows:

[0016] Step 3. Neutralization and Emulsification: Further cool the system to 40-50℃. Dissolve triethylamine (TEA) in 5-15 times its volume of acetone and slowly add it to the reaction system. Stir and neutralize at 40-50℃ for 20-40 minutes to convert the carboxyl groups on DMPA into ammonium carboxylate salts, forming hydrophilic centers. Place the rotor of a high-speed disperser in a flask and stir at 1500-2000 rpm. Slowly add 1.5-2.3 times its volume of deionized water to the system over 10-15 minutes. As water is added, the viscosity of the system first increases and then decreases, gradually changing from transparent to milky white, forming a preliminary emulsion. Continue high-speed shear dispersion for 20-40 minutes to obtain a uniform and stable pre-emulsion. The reaction process is as follows:

[0017]

[0018] Step 4. Post-chain extension in water: While stirring, maintain the system temperature at 30-35℃. Slowly add the prepared 8-12wt% ethylenediamine (EDA) aqueous solution to the emulsion through a dropping funnel over a period of approximately 15-25 minutes. EDA reacts with the remaining -NCO groups on the surface and inside the prepolymer latex particles to extend the chain in water, forming urea bonds, which further increases the molecular weight and emulsion stability. After the addition is complete, continue the reaction for 1-2 hours. The reaction process is as follows:

[0019]

[0020] Step 5. Solvent Removal: Connect the reaction system to a vacuum distillation apparatus and distill under reduced pressure at 40-50℃ to completely remove the acetone solvent from the system. After distillation, cool to room temperature, adjust the solid content of the system with deionized water, and filter (through a 400-mesh sieve) to obtain a multifunctional modified waterborne polyurethane emulsion, which is the MWPU emulsion.

[0021] Preferably, in step 1, the molecular weight of the polycarbonate diol is 1000-3000, the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 1000-3000, the DOPO diol is hydroxymethylated, and the hydroxyl equivalent ratio of the polycarbonate diol, the hydroxyl-terminated polydimethylsiloxane, and the DOPO diol is 15-16:2-3:1-2; the molar ratio of the NCO groups to the total OH groups in the isophorone diisocyanate is 1.5-2.5:1; and the amount of dibutyltin dilaurate is 0.05-0.2% of the mass of the isophorone diisocyanate.

[0022] Preferably, in step 2, the amount of dimethylolpropionic acid used is 6-8% of the mass of isophorone diisocyanate, and the amount of polyethylene glycol monomethyl ether with Mn=500-1000 is 8-12% of the mass of isophorone diisocyanate.

[0023] Preferably, the molar ratio of triethylamine to dimethylolpropionic acid in step 3 is 0.9-1.05:1.

[0024] Preferably, the amount of ethylenediamine used in step 4 is 0.1-0.2% of the mass of the pre-emulsion in step 3.

[0025] Preferably, in step 5, deionized water is used to adjust the solid content of the system to 30-40%.

[0026] Preferably, the fiber substrate is a natural cotton or linen fiber that has undergone surface treatment with an amino-containing silane coupling agent.

[0027] This invention provides a method for preparing a waterborne polyurethane fiber composite material, comprising the following steps:

[0028] The pretreated fiber substrate is completely immersed in a multifunctional modified waterborne polyurethane emulsion for 5-10 minutes. After removal, the liquid content is controlled at 50-80% by a rolling mill or scraper to ensure uniform resin adhesion. It is then pre-dried in an oven at 80-100℃ for 5-10 minutes to remove most of the moisture. Finally, it is cured at 130-150℃ for 15-25 minutes. During this process, the polyurethane segments complete the final cross-linking. At the same time, the amino groups on the fiber surface react with the residual -NCO or molecular chains in the polyurethane to form a strong chemical bond interface. After cooling, a waterborne polyurethane fiber composite material is obtained.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. Excellent comprehensive material performance and diversified functions: This invention achieves synergistic improvement in material performance by precisely introducing multiple functional structural units into the waterborne polyurethane molecular chain, breaking through the limitations of traditional single-functional materials. Specifically, the covalent bonding of DOPO diol (DOPO-HQ) endows the material with reliable flame retardant properties, solving the problems of easy migration and time-dependent decay of traditional additive flame retardants; the introduction of hydroxyl-terminated polydimethylsiloxane (PDMS-OH) optimizes the material's weather resistance, high and low temperature resistance, and surface hydrophobicity, improving the composite material's service stability in complex environments; the antistatic segments introduced by polyethylene glycol monomethyl ether (MPEG) effectively improve the defect of easy static electricity accumulation in fiber materials, broadening its application scenarios in static-sensitive fields such as electronics and textiles. Simultaneously, polycarbonate diol (PCDL) provides good mechanical support for the polyurethane main chain, enabling the composite material to possess both high strength and flexibility.

[0031] 2. Significantly Enhanced Interfacial Bonding and Improved Structural Stability: Addressing the critical issues of weak fiber-resin interfacial bonding and easy delamination in traditional composite materials, this invention proposes an interfacial modification scheme for fiber substrates. The fiber surface is treated with an amino-containing silane coupling agent (such as KH-550) to graft amino active functional groups onto its surface. These functional groups can chemically react with residual isocyanate groups (-NCO) in multifunctional modified waterborne polyurethane (MWPU) to form covalent bonds. Compared to traditional physical adsorption, this chemically bonded interface greatly enhances interlayer bonding, effectively preventing resin layer detachment and mechanical property degradation during use, thus significantly extending the overall structural stability and service life of the composite material.

[0032] 3. Outstanding green and environmentally friendly characteristics, aligning with industry development trends: This invention utilizes an entirely water-based system, with water as the dispersion medium. Only a small amount of acetone is used as a co-solvent during preparation, and this co-solvent is completely removed through vacuum distillation, resulting in a final product free of solvent residue. Compared to traditional solvent-based polyurethane composites, this invention reduces volatile organic compound (VOC) emissions at the source, lowering the harm to the production environment and operator health, while avoiding energy consumption and secondary pollution during solvent recovery. Furthermore, the use of natural fibers such as cotton and linen as the fiber substrate further enhances the material's environmental friendliness, aligning with the current development direction of green chemistry and low-carbon manufacturing. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the process flow for a method of preparing waterborne polyurethane fiber composite material proposed in this invention. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0035] Preparation Example 1: A specific method for pretreatment of fiber substrate includes the following steps: KH-550 silane coupling agent is mixed with ethanol and deionized water at a volume ratio of 1:80:20, the pH is adjusted to 4.5 with acetic acid, and the mixture is hydrolyzed and activated for 25 min. The fiber fabric is completely immersed in the treatment solution for 25 min. After removal, excess liquid is removed with rollers, and the fabric is dried at 100°C for 10 min and then cured at 120°C for 20 min.

[0036] The specific preparation method of the multifunctional modified waterborne polyurethane emulsion includes the following steps:

[0037] Step 1. Synthesis of the prepolymer: Under nitrogen protection, 135.0 g of polycarbonate diol (PCDL, Mn=2000), 22.5 g of hydroxyl-terminated polydimethylsiloxane (PDMS-OH, Mn=2000) and 15.0 g of DOPO diol (DOPO-HQ) were added to the reactor. After the mixture was heated to 80 °C and melted uniformly, 100 g of isophorone diisocyanate (IPDI) and 0.08 g of catalyst DBTDL were added. The mixture was reacted at 80 °C for 2.5 h to obtain the terminal-NCO prepolymer.

[0038] Step 2. Hydrophilic chain extension: Dissolve 7.0 g of dimethylolpropionic acid (DMPA) and 9.5 g of polyethylene glycol monomethyl ether (MPEG, Mn=750) together in 40.0 g of acetone, and slowly add the prepolymer dropwise over 30 min. React at 80 °C for 1.5 h.

[0039] Step 3. Neutralization and emulsification: Cool to 45°C, add 5.7g triethylamine (TEA) and 57.0g acetone to the system slowly, neutralize at 45°C for 30min, and slowly add 280.0g deionized water over 15min while stirring at 1800rpm. Continue high-speed dispersion for 30min to obtain a pre-emulsion.

[0040] Step 4. Post-chain extension in water: At 35℃, add 16.75g of 8wt% ethylenediamine (EDA) aqueous solution dropwise over 20min, and react for 1.5h;

[0041] Step 5. Solvent removal: Acetone is completely removed by vacuum distillation at 40°C. After cooling, water is added to adjust the solid content to 35%. The mixture is then filtered through a 400-mesh sieve to obtain a multifunctional modified waterborne polyurethane emulsion.

[0042] Preparation Example 2: A specific method for pretreatment of fiber substrate includes the following steps: KH-550 silane coupling agent is mixed with ethanol and deionized water at a volume ratio of 1:80:20, the pH is adjusted to 4.5 with acetic acid, and the mixture is hydrolyzed and activated for 25 min. The fiber fabric is completely immersed in the treatment solution for 25 min. After removal, excess liquid is removed with rollers, and the fabric is dried at 100°C for 10 min and then cured at 120°C for 20 min.

[0043] The specific preparation method of the multifunctional modified waterborne polyurethane emulsion includes the following steps:

[0044] Step 1. Synthesis of prepolymer: Under nitrogen protection, 112.5g PCDL (Mn=2000), 30.0g PDMS-OH (Mn=2000) and 7.5g DOPO-HQ were added to the reactor. After the mixture was heated to 80℃ and melted uniformly, 100.0g IPDI and 0.15g DBTDL were added, and the mixture was reacted at 80℃ for 3.0h.

[0045] Step 2. Hydrophilic chain extension: Dissolve 6.5g DMPA and 8.0g MPEG (Mn=750) in 30.0g acetone and add dropwise the prepolymer, react at 75℃ for 2.0h;

[0046] Step 3. Neutralization and emulsification: Cool to 40℃, add 4.9g TEA and 49.0g acetone to the system slowly, neutralize at 40℃ for 30min, and slowly add 250.0g deionized water over 15min while stirring at high speed at 2000rpm. Continue high-speed dispersion for 40min to obtain a pre-emulsion.

[0047] Step 4. Post-chain extension in water: At 30℃, add 8.0g of 10wt% ethylenediamine (EDA) aqueous solution dropwise over 20min, and react for 2.0h;

[0048] Step 5. Solvent removal: Acetone is completely removed by vacuum distillation at 45°C. After cooling, water is added to adjust the solid content to 32%. The mixture is then filtered through a 400-mesh sieve to obtain a multifunctional modified waterborne polyurethane emulsion.

[0049] Preparation Example 3: A specific method for pretreatment of fiber substrate includes the following steps: KH-550 silane coupling agent is mixed with ethanol and deionized water at a volume ratio of 1:80:20, the pH is adjusted to 4.5 with acetic acid, and the mixture is hydrolyzed and activated for 25 min. The fiber fabric is completely immersed in the treatment solution for 25 min. After removal, excess liquid is removed with rollers, and the fabric is dried at 100°C for 10 min and then cured at 120°C for 20 min.

[0050] The specific preparation method of the multifunctional modified waterborne polyurethane emulsion includes the following steps:

[0051] Step 1. Synthesis of prepolymer: Under nitrogen protection, 150g PCDL (Mn=2000), 20.0g PDMS-OH (Mn=2000) and 10.0g DOPO-HQ were added to the reactor. After the mixture was heated to 85℃ and melted uniformly, 100g IPDI and 0.10g DBTDL were added, and the mixture was reacted at 85℃ for 2.0h to obtain the terminal-NCO prepolymer.

[0052] Step 2. Hydrophilic chain extension: Dissolve 7.0g DMPA and 10.0g MPEG (Mn=750) together in 35.0g acetone, and slowly add the prepolymer dropwise over 30min. React at 85℃ for 1.0h.

[0053] Step 3. Neutralization and emulsification: Cool to 50°C, add 5.3g triethylamine (TEA) and 53.0g acetone to the system slowly, neutralize at 50°C for 30min, and slowly add 300.0g deionized water over 15min while stirring at 1500rpm. Continue high-speed dispersion for 20min to obtain a pre-emulsion.

[0054] Step 4. Post-chain extension in water: At 35℃, add 7.0g of 10wt% ethylenediamine (EDA) aqueous solution dropwise over 20min, and react for 1.0h;

[0055] Step 5. Solvent removal: Acetone is completely removed by vacuum distillation at 40°C. After cooling, water is added to adjust the solid content to 38%. The mixture is then filtered through a 400-mesh sieve to obtain a multifunctional modified waterborne polyurethane emulsion.

[0056] Comparative Preparation Example 1: The difference between Comparative Preparation Example 1 and Preparation Example 1 is that the aqueous polyurethane emulsion was prepared only from PCDL, IPDI, and DMPA, and did not contain functional monomers such as PDMS-OH, DOPO-HQ, and MPEG.

[0057] Comparative Preparation Example 2: The difference between Comparative Preparation Example 2 and Preparation Example 1 is that DOPO-HQ is not added in the method of Preparation Example 1.

[0058] Comparative Preparation Example 3: The difference between Comparative Preparation Example 3 and Preparation Example 1 is that PDMS-OH is not added in the method of Preparation Example 1.

[0059] Comparative Preparation Example 4: The difference between Comparative Preparation Example 4 and Preparation Example 1 is that MPEG is not added in the method of Preparation Example 1.

[0060] Comparative Preparation Example 5: The difference between Comparative Preparation Example 5 and Preparation Example 1 is that DOPO-HQ and PDMS-OH are not added in the method of Preparation Example 1.

[0061] Comparative Preparation Example 6: The difference between Comparative Preparation Example 6 and Preparation Example 1 is that DOPO-HQ and MPEG are not added in the method of Preparation Example 1.

[0062] Comparative Preparation Example 7: The difference between Comparative Preparation Example 7 and Preparation Example 1 is that PDMS-OH and MPEG are not added in the method of Preparation Example 1.

[0063] Example 1: A method for preparing a waterborne polyurethane fiber composite material, comprising the following steps:

[0064] The pretreated fiber substrate was completely immersed in the multifunctional modified waterborne polyurethane emulsion prepared in Preparation Example 1 and fully immersed for 8 minutes. After being removed, the liquid content was controlled to 80% by rolling mill or scraper. It was first pre-dried in a drying tunnel at 100°C for 8 minutes, and then cured at 140°C for 20 minutes. After cooling, a waterborne polyurethane fiber composite material was obtained.

[0065] Example 2: A method for preparing a waterborne polyurethane fiber composite material, comprising the following steps:

[0066] The pretreated fiber substrate was completely immersed in the multifunctional modified waterborne polyurethane emulsion prepared in Preparation Example 2 and fully immersed for 5 minutes. After being removed, the liquid content was controlled to 70% by rolling or scraping. It was first pre-dried in a drying tunnel at 90°C for 10 minutes, and then cured at 130°C for 25 minutes. After cooling, a waterborne polyurethane fiber composite material was obtained.

[0067] Example 3: A method for preparing a waterborne polyurethane fiber composite material, comprising the following steps:

[0068] The pretreated fiber substrate was completely immersed in the multifunctional modified waterborne polyurethane emulsion prepared in Preparation Example 3 and fully impregnated for 10 minutes. After being removed, the liquid content was controlled to 60% by rolling mill or scraper. It was first pre-dried in an oven at 80°C for 10 minutes, and then cured at 150°C for 15 minutes. After cooling, a waterborne polyurethane fiber composite material was obtained.

[0069] Comparative Example 1: Based on Example 1, the difference is that: the unmodified ordinary aqueous polyurethane emulsion of Comparative Preparation 1 was used, and the rest was the same as in Example 1.

[0070] Comparative Example 2: Based on Example 1, the difference is that a MWPU emulsion lacking DOPO-HQ was used in Comparative Preparation 2, otherwise the same as in Example 1.

[0071] Comparative Example 3: Based on Example 1, the difference is that a MWPU emulsion lacking PDMS-OH was prepared using the comparative preparation, otherwise it is the same as Example 1.

[0072] Comparative Example 4: Based on Example 1, the difference is that a MWPU emulsion lacking MPEG was used in Comparative Preparation 4, otherwise the same as in Example 1.

[0073] Comparative Example 5: Based on Example 1, except that a MWPU emulsion lacking DOPO-HQ and PDMS-OH was used in Comparative Preparation 5, otherwise the same as in Example 1.

[0074] Comparative Example 6: Based on Example 1, the difference is that a comparative preparation 6 MWPU emulsion lacking DOPO-HQ and MPEG was used, otherwise it was the same as Example 1.

[0075] Comparative Example 7: Based on Example 1, except that a MWPU emulsion lacking PDMS-OH and MPEG was used in Comparative Preparation 7, otherwise the same as in Example 1.

[0076] Performance testing:

[0077] 1. Mechanical property testing: The fiber samples prepared in Examples 1-3 and Comparative Examples 1-7 were tested on an Instron 3345 universal testing machine according to GB / T 3916-2013 "Determination of breaking strength and elongation at break of single yarn in packaged textiles (CRE method)". The clamping distance was 25 mm, the tensile speed was 10 mm / min, and the test was conducted under standard temperature and humidity conditions. The tensile strength and elongation at break of the sample were recorded. Each sample was tested 20 times and the average value was taken. The experimental results are shown in Table 1.

[0078] 2. Water Contact Angle Test: The fiber samples prepared in Examples 1-3 and Comparative Examples 1-7 were tested according to GB / T 42694-2023 "Detection and Evaluation of the Wetting Resistance of Textile Surfaces - Contact Angle and Roll-Off Angle Method". The composite materials were made into flat, clean, and scratch-free sample pieces (at least 50mm × 50mm). The test was conducted on a static contact angle measuring instrument. A drop of ultrapure water (usually 2-5µL) was dropped onto the sample surface using a micro-syringe. After the droplet contacted the surface, a static image of its side was captured by the instrument's high-speed camera within 5 seconds. The angle measurement method (tangent method) or Young-Laplace equation fitting method was used. The image was analyzed by the instrument software to calculate the angle between the tangent of the droplet profile and the solid surface at the liquid-solid-gas three-phase contact point. This angle is the water contact angle. At least 5 points were randomly measured at different locations on the same sample surface, and the arithmetic mean was taken as the water contact angle of the sample. The experimental results are shown in Table 1.

[0079] 3. Surface Resistance Test: The fiber samples prepared in Examples 1-3 and Comparative Examples 1-7 were tested on a resistance tester in accordance with GB / T 31838.2-2019 "Dielectric and Resistive Properties of Solid Insulating Materials - Part 2: Resistive Properties - Test Methods for Volume Resistance and Volume Resistivity, Surface Resistance and Surface Resistivity". The composite material was made into a flat, smooth sheet sample (100mm×100mm) to ensure that the surface was clean and free of contamination. The sample was placed on an insulating base, a high resistance meter was connected, and the specified DC test voltage was applied. After charging for 60 seconds, a stable resistance reading was read. Each sample was tested at least 3 times, and the average value was taken. The experimental results are shown in Table 1.

[0080] 4. Limiting Oxygen Index (LOI) Test: The fiber samples prepared in Examples 1-3 and Comparative Examples 1-7 were tested using an HC-2C oxygen index tester according to GB / T5454-1997 "Test for Burning Performance of Textiles - Oxygen Index Method". The samples were prepared as fiber bundles with a length of 150 mm and a width of 6.5 mm, vertically clamped in the center of the combustion chamber, and in an environment of 23±2℃ and 50±5% humidity, the oxygen-nitrogen mixed airflow was adjusted to determine the minimum oxygen concentration required for the sample to maintain stable combustion. The results were expressed as a volume percentage. Each sample was tested 5 times and the average value was taken. The experimental results are shown in Table 1.

[0081] 5. Vertical Burning (UL-94) Test: The fiber samples prepared in Examples 1-3 and Comparative Examples 1-5 were tested on a CZF-5 horizontal and vertical burning tester according to the V-0, V-1, and V-2 rating methods specified in the ANSI / UL-94-2013 standard. The samples were cut into strips 130 mm long and 13 mm wide, fixed vertically, and a Bunsen burner flame (flame height 20 mm) was applied to the center of the lower end of the sample for 10 seconds. The afterflame time, whether the afterflame spread to the fixture, and whether there were any molten drips that ignited the absorbent cotton were recorded. The burning rating was determined based on the test results after two flame applications. The experimental results are shown in Table 1.

[0082] 6. Water resistance test: The fiber samples prepared in Examples 1-3 and Comparative Examples 1-7 were tested in a constant temperature water bath according to GB / T 1034-2008 "Determination of water absorption of plastics". The samples were completely immersed in distilled water or deionized water, and the water temperature was maintained at 23±0.5℃. It was ensured that all surfaces of the samples were in full contact with the water and did not overlap. After soaking for 24±0.5h, the samples were taken out and all visible water droplets on the surface were quickly wiped off with filter paper or absorbent cloth. The water absorption was calculated. The experimental results are shown in Table 1.

[0083] 7. Abrasion resistance test: The fiber samples prepared in Examples 1-3 and Comparative Examples 1-7 were tested using a Taber abrasion tester with a CS-10 grinding wheel, according to GB / T 1768-2006 "Determination of abrasion resistance of paints and varnishes - Rotating rubber grinding wheel method". A load of 750g was applied and the number of friction cycles was set to 1000. The mass loss of the fiber samples was measured. The experimental results are shown in Table 1.

[0084] Table 1. Performance Test Results

[0085]

[0086] Data Analysis:

[0087] 1. Comprehensive performance analysis:

[0088] Example 1 exhibited the most balanced and outstanding performance, with high tensile strength (48.3 MPa) and elongation at break (400%), indicating that the material combines high strength with good toughness; its limiting oxygen index (LOI) was as high as 30.5%, and it passed UL-94, V-0 rating (the highest flame retardant rating), demonstrating excellent flame retardancy; its water contact angle was 115°, exhibiting excellent hydrophobicity; and its surface resistivity was 6.8 × 10⁻⁶. 9 Ω, reaching the range of antistatic materials; water absorption rate as low as 3.2% in 24 hours, with strong water resistance; weight loss of 70mg after 1000 cycles of friction, with good wear resistance;

[0089] The performance of Examples 2 and 3 was at the same level as that of Example 1, with slight fluctuations (e.g., the LOI of Example 2 was 28.6% and still reached V-0, and the tensile strength of Example 3 was 47.6 MPa). This demonstrates that by fine-tuning the proportions of components such as PCDL, PDMS-OH, and DOPO-HQ (as shown by the formulation differences in Examples 1-3), a certain property of the material can be fine-tuned while maintaining high performance to meet different application priorities, reflecting the flexibility of formulation design.

[0090] 2. Analysis of the roles of key functional components:

[0091] Comparative Example 1 (using ordinary WPU and without functional monomers in the formulation): its tensile strength (30.0 MPa) and elongation at break (280%) are much lower than all examples. This huge difference is not only due to the lack of functional monomers, but more importantly, it is because ordinary WPU and fibers are only physically adsorbed, and the interfacial bonding is weak. In contrast, the examples were treated with silane coupling agents, which formed a strong chemical bond interface, thereby greatly improving the overall mechanical properties of the composite material.

[0092] Comparative Example 2 (DOPO-HQ missing): The LOI dropped sharply to 21.0%, and the UL-94 rating dropped to V-2, indicating a severe deterioration in flame retardant performance. This shows that the DOPO structural unit is the key to endowing the material with inherent flame retardancy. It is introduced through covalent bonding, avoiding the disadvantages of easy migration and short-lasting effect of physically added flame retardants. Comparative Examples 5 and 6 (both missing DOPO-HQ) also showed poor flame retardant performance, further confirming the core role of DOPO.

[0093] Comparative Example 3 (PDMS-OH missing): The water contact angle decreased to 75°, the water absorption rate increased to 8.0% after 24 hours, and the wear resistance weight loss increased to 120 mg. This indicates that the introduction of PDMS-OH significantly enhanced the hydrophobicity and water resistance of the material. At the same time, its soft siloxane segments also improved the wear resistance and flexibility of the coating. Comparative Examples 5 and 7 (both lacking PDMS-OH) also showed a similar trend of decreasing water resistance.

[0094] Comparative Example 4 (without MPEG): Surface resistivity increases sharply to ≥10 13 Ω completely lost its antistatic ability, which proves that the hydrophilic segment introduced by MPEG is the key to forming a charge leakage path and achieving a durable antistatic function. Comparative examples 6 and 7 (both lacking MPEG) also had very poor antistatic performance.

[0095] 3. Synergistic effect analysis:

[0096] Comparative Examples 5 (lacking DOPO-HQ and PDMS-OH), 6 (lacking DOPO-HQ and MPEG), and 7 (lacking PDMS-OH and MPEG) all exhibited poor performance across various aspects, indicating that the absence of any single function would affect the overall performance. In contrast, in the embodiments, each functional unit exists stably in the same system through chemical bonding, without interfering with each other and working together. The strong chemical bonding interface not only improves mechanical properties but also prevents the functional coating from falling off due to interface damage during use, thereby ensuring the durability of functions such as flame retardancy and antistatic properties. This is demonstrated in the comparison between the poor abrasion resistance of Comparative Example 1 (weight loss of 150 mg) and the good abrasion resistance of the embodiments (weight loss of 70-90 mg).

[0097] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a waterborne polyurethane fiber composite material, characterized in that, Includes the following steps: The pretreated fiber substrate is completely immersed in a multifunctional modified waterborne polyurethane emulsion for 5-10 minutes. After removal, the liquid content is controlled at 50-80% by a rolling mill or scraper to ensure uniform resin adhesion. It is then pre-dried in an oven at 80-100℃ for 5-10 minutes to remove most of the moisture. Finally, it is cured at 130-150℃ for 15-25 minutes. After cooling, a waterborne polyurethane fiber composite material is obtained. The specific method for pretreatment of the fiber substrate is as follows: KH-550 silane coupling agent is mixed with ethanol and deionized water at a volume ratio of 1:80:20, the pH is adjusted to 4-5 with acetic acid, and the substrate is hydrolyzed and activated for 25-35 minutes. The fiber substrate is then completely immersed in the treatment solution for 20-30 minutes. After removal, excess liquid is removed with rollers, and the substrate is dried at 80-100℃ for 8-12 minutes. Finally, it is cured at 110-120℃ for 15-25 minutes. The preparation method of the multifunctional modified waterborne polyurethane emulsion is as follows: Step 1. Synthesis of prepolymer: Polycarbonate diol, hydroxyl-terminated polydimethylsiloxane and DOPO diol are mixed and melted, and then reacted with isophorone diisocyanate in the presence of a catalyst to obtain a -NCO-terminated modified polyurethane prepolymer. Step 2. Hydrophilic chain extension: Dimethylolpropionic acid and polyethylene glycol monomethyl ether are dissolved in acetone and then added dropwise to the prepolymer obtained in Step 1 to carry out the chain extension reaction; Step 3. Neutralization and emulsification: Cool the system obtained in Step 2 to 40-50℃, add triethylamine for neutralization, and then add deionized water under high-speed stirring for emulsification to obtain a pre-emulsion; Step 4. Chain extension in water: Add ethylenediamine aqueous solution dropwise to the pre-emulsion obtained in step 3 to carry out the chain extension reaction; Step 5. Solvent removal: Remove acetone from the system obtained in step 4, adjust the solid content of the system with deionized water, and obtain a multifunctional modified waterborne polyurethane emulsion after filtration.

2. The method for preparing a waterborne polyurethane fiber composite material according to claim 1, characterized in that, In step 1, the molecular weight of the polycarbonate diol is 1000-3000, the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 1000-3000, and the DOPO diol is hydroxymethylated; the hydroxyl equivalent ratio of the polycarbonate diol, the hydroxyl-terminated polydimethylsiloxane, and the DOPO diol is 15-16:2-3:1-2; the molar ratio of the NCO groups to the total OH groups in the isophorone diisocyanate is 1.5-2.5:

1.

3. The method for preparing a waterborne polyurethane fiber composite material according to claim 1, characterized in that, In step 2, the amount of dimethylolpropionic acid used is 6-8% of the mass of isophorone diisocyanate; the molecular weight of polyethylene glycol monomethyl ether is 500-1000, and its amount is 8-12% of the mass of isophorone diisocyanate.

4. The method for preparing a waterborne polyurethane fiber composite material according to claim 1, characterized in that, In step 3, the molar ratio of triethylamine to dimethylolpropionic acid is 0.9-1.05:

1.

5. The method for preparing a waterborne polyurethane fiber composite material according to claim 1, characterized in that, In step 4, the amount of ethylenediamine used is 0.1-0.2% of the mass of the pre-emulsion in step 3.

6. The method for preparing a waterborne polyurethane fiber composite material according to claim 1, characterized in that, In step 5, deionized water is used to adjust the solid content of the system to 30-40%.

7. The method for preparing a waterborne polyurethane fiber composite material according to claim 1, characterized in that, The fiber substrate is cotton or linen.

8. A waterborne polyurethane fiber composite material, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

9. The application of the waterborne polyurethane fiber composite material according to claim 8 in industrial textiles.

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