A waterproof and breathable polyurethane film and a preparation method thereof

Abstract

The application belongs to the technical field of polyurethane films, and particularly relates to a waterproof and breathable polyurethane film and a preparation method thereof. The polyurethane film comprises the following components in parts by weight: 40-50 parts of polyurethane resin, 3-4 parts of functional chitosan oligosaccharide, 6-8 parts of polystyrene, 1-2 parts of mesoporous silica nanoparticles, 0.5-0.8 parts of a crosslinking agent, and 40-50 parts of an organic solvent. The polyurethane film is prepared by using polyurethane resin as a main component, adding hydrophobic polystyrene, porous mesoporous silica nanoparticles and functional chitosan oligosaccharide, and crosslinking the components by means of aziridine crosslinking agent to form a polyurethane film with a compact structure. The polyurethane film not only improves the mechanical properties, waterproof and breathable properties, but also greatly enhances the antibacterial properties and flame-retardant properties of the polyurethane film.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane film technology, specifically relating to a waterproof and breathable polyurethane film and its preparation method. Background Technology

[0002] Polyurethane film is a polymer film material made from polyurethane. It has a unique block molecular structure, composed of alternating flexible and rigid segments. The flexible segments are mainly composed of oligomeric polyols, while the rigid segments are generated by the reaction of isocyanates and small molecule chain extenders. This structure endows polyurethane film with good wear resistance, flexibility, high elasticity, and waterproof and breathable properties, and it is widely used in clothing, medical, packaging and other fields. In daily life, viral and bacterial infections seriously threaten people's health. Polyurethane film itself does not have bactericidal effect, so antibacterial agents are usually added or modified to improve the antibacterial properties of polyurethane film.

[0003] Chinese patent application No. 202310770952.0 discloses a catechol-grafted photosensitive chitosan oligosaccharide-modified polyurethane film, its preparation method, and its application. First, using chitosan oligosaccharide and methacrylic anhydride as main raw materials, a carbon-carbon double-bond-grafted photosensitive chitosan oligosaccharide is synthesized via methacrylation. Then, it is reacted with 3,4-dihydroxybenzoic acid, and a catechol-grafted photosensitive chitosan oligosaccharide is synthesized via an EDC / NHS coupling reaction. Finally, it is mixed with the prepared photocurable waterborne polyurethane and a photoinitiator, and a catechol-grafted photosensitive chitosan oligosaccharide-modified polyurethane film is synthesized via a photocuring reaction. This patent application has the following problems:

[0004] 1. Chitosan oligosaccharides contain abundant hydroxyl and amino groups, and have good water solubility, biocompatibility and antibacterial properties. While giving polyurethane films antibacterial effects, they also increase their hydrophilicity, which leads to a decrease in the waterproof performance of polyurethane films and limits the application of chitosan oligosaccharides in waterproof polyurethane films.

[0005] 2. The antibacterial rate of the polyurethane film prepared against Staphylococcus aureus is only 36-55%. The protonated amino groups on chitosan oligosaccharides are the key to the antibacterial activity of chitosan oligosaccharides. The amino groups in its molecular structure serve as reaction sites, and carbon-carbon double bonds and catechols are grafted in sequence. The higher the overall grafting rate, the fewer free amino groups in the structure, and the lower the antibacterial rate of the film. When modifying chitosan oligosaccharides by grafting functionalization, the impact on antibacterial properties needs to be considered.

[0006] Therefore, further research is needed to obtain functionalized modified chitosan oligosaccharides that maintain good antibacterial properties and apply them to waterproof polyurethane films. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a waterproof and breathable polyurethane film. The film uses polyurethane resin as the main component, with the addition of hydrophobic polystyrene, porous mesoporous silica nanoparticles, and functional chitosan oligosaccharides. A aziridine crosslinking agent is used to crosslink the components, forming a dense polyurethane film. This not only improves the mechanical properties and waterproof and breathable performance of the polyurethane film but also significantly enhances its antibacterial and flame-retardant properties.

[0008] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0009] A waterproof and breathable polyurethane film, the polyurethane film comprising the following components by weight: 40-50 parts polyurethane resin, 3-4 parts functionalized chitosan oligosaccharide, 6-8 parts polystyrene, 1-2 parts mesoporous silica nanoparticles, 0.5-0.8 parts crosslinking agent, and 40-50 parts organic solvent.

[0010] Furthermore, the crosslinking agent is a aziridine crosslinking agent.

[0011] Furthermore, the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 2-3:1.

[0012] Furthermore, the preparation method of the functionalized chitosan oligosaccharide is as follows:

[0013] S1. Dimethyl 2-hydroxyethylphosphonate and N,N'-carbonyldiimidazole were added to acetonitrile and stirred at room temperature for 6-8 hours. Then, an aqueous solution of chitosan oligosaccharide was added and the reaction was continued at 40-50℃ for 10-12 hours. After the reaction was completed, the modified chitosan oligosaccharide was obtained by dialysis with pure water and drying.

[0014] S2. Add the modified chitosan oligosaccharide to PBS buffer, stir to dissolve, add quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide, place at room temperature, stir and react for 12-15 h. After the reaction is complete, dialyze with pure water and dry to obtain functionalized chitosan oligosaccharide.

[0015] Further, in step S1, the mass ratio of chitosan oligosaccharide, dimethyl 2-hydroxyethylphosphonate, and N,N'-carbonyldiimidazole is 1:0.2-0.3:0.3-0.35.

[0016] Furthermore, the concentration of the chitosan oligosaccharide aqueous solution in step S1 is 8-10 wt%.

[0017] Further, the preparation method of the quaternary phosphonium salt compound in step S2 is as follows: triphenylphosphine is added to N,N-dimethylformamide, and under nitrogen protection, the temperature is raised to 115-120℃, and 4-chlorobutyric acid is slowly added dropwise. After the addition is complete, the reaction continues for 20-24 hours to obtain the quaternary phosphonium salt compound.

[0018] Furthermore, the molar ratio of triphenylphosphine to 4-chlorobutyric acid is 1:1.1-1.2.

[0019] Further, in step S2, the mass ratio of the modified chitosan oligosaccharide, the quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide is 1:1.1-1.2:0.55-0.6:0.65-0.7.

[0020] The present invention also provides a method for preparing a waterproof and breathable polyurethane film, comprising the following steps: according to the weight ratio, polystyrene and tetrahydrofuran are first mixed evenly to obtain a mixture; polyurethane resin and N,N-dimethylformamide are then mixed evenly; functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and crosslinking agent are added; the mixture is stirred at 80-85°C for 1.5-2 hours; the mixture is then added; stirring is continued for 20-30 minutes; after cooling, the mixture is coated onto release paper and dried in an oven to obtain a polyurethane film.

[0021] Furthermore, the drying temperature is 110-120℃, and the drying time is 8-10 minutes.

[0022] The present invention has the following beneficial effects:

[0023] 1. This invention uses chitosan oligosaccharide as a raw material. First, chitosan oligosaccharide is reacted with dimethyl 2-hydroxyethylphosphonate to graft hydrophobic and flame-retardant phosphonate groups onto the chitosan oligosaccharide, resulting in modified chitosan oligosaccharide. Then, the modified chitosan oligosaccharide is reacted with a quaternary phosphonium salt compound to further graft flame-retardant and antibacterial triphenyl quaternary phosphonium salt groups onto the chitosan oligosaccharide, resulting in functionalized chitosan oligosaccharide. The flame-retardant and antibacterial groups grafted onto the chitosan oligosaccharide obtained by this invention greatly enhance its antibacterial and flame-retardant properties.

[0024] 2. This invention uses functionalized chitosan oligosaccharides to modify polyurethane films. The phosphonate groups and triphenyl quaternary phosphonium salt groups grafted onto the chitosan oligosaccharides can work synergistically to endow polyurethane with good flame retardant properties. Moreover, the triphenyl quaternary phosphonium salt groups grafted onto the chitosan oligosaccharides can also overcome the defects of reduced free amino groups and decreased antibacterial rate caused by the grafting reaction. They work synergistically with chitosan molecules to greatly improve the antibacterial properties of polyurethane films.

[0025] 3. This invention uses polyurethane resin as the main component, and adds hydrophobic polystyrene, porous mesoporous silica nanoparticles and functional chitosan oligosaccharides. The components are cross-linked with aziridine cross-linking agent to form a dense polyurethane film. This not only improves the mechanical properties and waterproof and breathable properties of the polyurethane film, but also greatly enhances its antibacterial and flame-retardant properties. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] In the technical solution of this invention, all chemical reagents used are commercially available. Specifically, the polyurethane resin was purchased from Zhejiang Huafeng Synthetic Resin Co., Ltd., model JF-A-WV7020; the mesoporous silica nanoparticles were purchased from Beijing Zhongke Keyou Technology Co., Ltd.; chitosan oligosaccharide (molecular weight 1500, degree of deacetylation 90%); polystyrene CAS number 9003-53-6; aziridine crosslinking agent CAS number 64265-57-2; the PBS buffer, with a pH of 5, was prepared from potassium dihydrogen phosphate and disodium hydrogen phosphate; and dimethyl 2-hydroxyethylphosphonate CAS number 54. 731-72-5; N,N'-carbonyldiimidazole CAS No. 530-62-1; 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride CAS No. 25952-53-8; N-hydroxysuccinimide CAS No. 6066-82-6; Triphenylphosphine CAS No. 603-35-0; 4-chlorobutyric acid CAS No. 627-00-9; Acetonitrile CAS No. 75-05-8; N,N-dimethylformamide CAS No. 68-12-2; Tetrahydrofuran CAS No. 109-99-9; Dichloromethane CAS No. 75-09-2.

[0028] Example 1

[0029] This embodiment provides a waterproof and breathable polyurethane film, comprising the following components by weight: 50 parts polyurethane resin, 4 parts functionalized chitosan oligosaccharide, 7 parts polystyrene, 2 parts mesoporous silica nanoparticles, 0.8 parts crosslinking agent, and 40 parts organic solvent; wherein the crosslinking agent is an aziridine crosslinking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 3:1.

[0030] The preparation method of functionalized chitosan oligosaccharides is as follows:

[0031] S1. Dimethyl 2-hydroxyethylphosphonate and N,N'-carbonyldiimidazole were added to acetonitrile and stirred at room temperature for 8 hours. Then, an aqueous solution of chitosan oligosaccharide was added, and the reaction was continued at 50°C for 10 hours. After the reaction was completed, the mixture was dialyzed with pure water and dried to obtain modified chitosan oligosaccharide. The mass ratio of chitosan oligosaccharide, dimethyl 2-hydroxyethylphosphonate, and N,N'-carbonyldiimidazole was 1:0.3:0.35, and the concentration of the chitosan oligosaccharide aqueous solution was 9 wt%.

[0032] S2. Add the modified chitosan oligosaccharide to PBS buffer and stir to dissolve. Add the quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide. Place at room temperature and stir for 15 hours. After the reaction is complete, dialyze with pure water and dry to obtain functionalized chitosan oligosaccharide. The mass ratio of modified chitosan oligosaccharide, quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide is 1:1.2:0.6:0.7, and the amount of PBS buffer is 10 times the mass of modified chitosan oligosaccharide.

[0033] The preparation method of the quaternary phosphonium salt compound in step S2 is as follows: 20.0 g of triphenylphosphine was added to 400 mL of N,N-dimethylformamide. Under nitrogen protection, the temperature was raised to 120 °C, and 10.3 g of 4-chlorobutyric acid was slowly added dropwise. After the addition was complete, the reaction was continued for 24 h. After the reaction was completed, the mixture was cooled, and water and dichloromethane were added for extraction. The organic phase was then extracted once more with water. The aqueous phase was collected and concentrated under reduced pressure to obtain 24.5 g of the quaternary phosphonium salt compound, wherein the molar ratio of triphenylphosphine to 4-chlorobutyric acid was 1:1.1; Quaternary phosphonium salt compound: ESI (m / z): 385.1 [M+H] + , 1 H-NMR (600MHz, DMSO-d6, δppm): 12.01 (s, 1H), 7.35-7.38 (m, 9H), 7.33 (d, J=8.4Hz, 6H), 2.36-2.42 (m, 4H), 1.62 (m, 2H).

[0034] This embodiment also provides a method for preparing a waterproof and breathable polyurethane film, comprising the following steps: according to the weight ratio, polystyrene and tetrahydrofuran are first mixed evenly to obtain a mixture; polyurethane resin and N,N-dimethylformamide are then mixed evenly; functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and crosslinking agent are added; the mixture is stirred at 85°C for 1.5 h; the mixture is then added; stirring is continued for 30 min; after cooling, the mixture is coated onto release paper and dried in an oven to obtain a polyurethane film; wherein the drying temperature is 120°C and the drying time is 8 min.

[0035] Example 2

[0036] This embodiment provides a waterproof and breathable polyurethane film, comprising the following components by weight: 45 parts polyurethane resin, 3 parts functionalized chitosan oligosaccharide, 8 parts polystyrene, 1.5 parts mesoporous silica nanoparticles, 0.6 parts crosslinking agent, and 45 parts organic solvent; wherein the crosslinking agent is an aziridine crosslinking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 2.5:1.

[0037] The preparation method of functionalized chitosan oligosaccharides is as follows:

[0038] S1. Dimethyl 2-hydroxyethylphosphonate and N,N'-carbonyldiimidazole were added to acetonitrile and stirred at room temperature for 7 h. Then, an aqueous solution of chitosan oligosaccharide was added, and the reaction was continued at 40 °C for 12 h. After the reaction was completed, the mixture was dialyzed with pure water and dried to obtain modified chitosan oligosaccharide. The mass ratio of chitosan oligosaccharide, dimethyl 2-hydroxyethylphosphonate, and N,N'-carbonyldiimidazole was 1:0.25:0.33, and the concentration of the chitosan oligosaccharide aqueous solution was 10 wt%.

[0039] S2. Add the modified chitosan oligosaccharide to PBS buffer and stir to dissolve. Add the quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide. Place at room temperature and stir for 13 hours. After the reaction is complete, dialyze with pure water and dry to obtain functionalized chitosan oligosaccharide. The mass ratio of modified chitosan oligosaccharide, quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide is 1:1.15:0.58:0.67, and the amount of PBS buffer is 10 times the mass of modified chitosan oligosaccharide.

[0040] This embodiment also provides a method for preparing a waterproof and breathable polyurethane film, comprising the following steps: according to the weight ratio, polystyrene and tetrahydrofuran are first mixed evenly to obtain a mixture; polyurethane resin and N,N-dimethylformamide are then mixed evenly; functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and crosslinking agent are added; the mixture is stirred at 80°C for 2 hours; the mixture is then added; stirring is continued for 20 minutes; after cooling, the mixture is coated onto release paper and dried in an oven to obtain a polyurethane film; wherein the drying temperature is 110°C and the drying time is 10 minutes.

[0041] Example 3

[0042] This embodiment provides a waterproof and breathable polyurethane film, comprising the following components by weight: 40 parts polyurethane resin, 3.5 parts functionalized chitosan oligosaccharide, 6 parts polystyrene, 1 part mesoporous silica nanoparticles, 0.5 parts crosslinking agent, and 50 parts organic solvent; wherein the crosslinking agent is an aziridine crosslinking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 2:1.

[0043] The preparation method of functionalized chitosan oligosaccharides is as follows:

[0044] S1. Dimethyl 2-hydroxyethylphosphonate and N,N'-carbonyldiimidazole were added to acetonitrile and stirred at room temperature for 6 hours. Then, an aqueous solution of chitosan oligosaccharide was added, and the reaction was continued at 45°C for 11 hours. After the reaction was completed, the mixture was dialyzed with pure water and dried to obtain modified chitosan oligosaccharide. The mass ratio of chitosan oligosaccharide, dimethyl 2-hydroxyethylphosphonate, and N,N'-carbonyldiimidazole was 1:0.2:0.3, and the concentration of the chitosan oligosaccharide aqueous solution was 8 wt%.

[0045] S2. Add the modified chitosan oligosaccharide to PBS buffer and stir to dissolve. Add the quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide. Place at room temperature and stir for 12 hours. After the reaction is complete, dialyze with pure water and dry to obtain functionalized chitosan oligosaccharide. The mass ratio of modified chitosan oligosaccharide, quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide is 1:1.1:0.55:0.65, and the amount of PBS buffer is 10 times the mass of modified chitosan oligosaccharide.

[0046] This embodiment also provides a method for preparing a waterproof and breathable polyurethane film, comprising the following steps: according to the weight ratio, polystyrene and tetrahydrofuran are first mixed evenly to obtain a mixture; polyurethane resin and N,N-dimethylformamide are then mixed evenly; functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and crosslinking agent are added; the mixture is stirred at 83°C for 1.8 h; the mixture is then added; stirring is continued for 25 min; after cooling, the mixture is coated onto release paper and dried in an oven to obtain a polyurethane film; wherein the drying temperature is 115°C and the drying time is 9 min.

[0047] Example 4

[0048] This embodiment provides a waterproof and breathable polyurethane film, comprising the following components by weight: 50 parts polyurethane resin, 3 parts functionalized chitosan oligosaccharide, 6 parts polystyrene, 1.5 parts mesoporous silica nanoparticles, 0.7 parts crosslinking agent, and 45 parts organic solvent; wherein the crosslinking agent is an aziridine crosslinking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 3:1.

[0049] The preparation method of functionalized chitosan oligosaccharides is as follows:

[0050] S1 is the same as step S1 in Example 2;

[0051] S2 is the same as step S2 in Example 1;

[0052] This embodiment also provides a method for preparing a waterproof and breathable polyurethane film, comprising the following steps: according to the weight ratio, polystyrene and tetrahydrofuran are first mixed evenly to obtain a mixture; polyurethane resin and N,N-dimethylformamide are then mixed evenly; functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and crosslinking agent are added; the mixture is stirred at 85°C for 2 hours; the mixture is then added; stirring is continued for 20 minutes; after cooling, the mixture is coated onto release paper and dried in an oven to obtain a polyurethane film; wherein the drying temperature is 110°C and the drying time is 9 minutes.

[0053] Comparative Example 1

[0054] This comparative example provides a waterproof and breathable polyurethane film, comprising the following components by weight: 50 parts polyurethane resin, 4 parts modified chitosan oligosaccharide, 7 parts polystyrene, 2 parts mesoporous silica nanoparticles, 0.8 parts crosslinking agent, and 40 parts organic solvent; wherein the crosslinking agent is an aziridine crosslinking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 3:1.

[0055] The preparation method of modified chitosan oligosaccharide is the same as step S1 in Example 1.

[0056] The preparation method of a waterproof and breathable polyurethane film is the same as that in Example 1.

[0057] Comparative Example 2

[0058] This comparative example provides a waterproof and breathable polyurethane film, comprising the following components by weight: 50 parts polyurethane resin, 4 parts functionalized chitosan oligosaccharide, 7 parts polystyrene, 2 parts mesoporous silica nanoparticles, 0.8 parts crosslinking agent, and 40 parts organic solvent; wherein the crosslinking agent is an aziridine crosslinking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 3:1.

[0059] The preparation method of functionalized chitosan oligosaccharide is as follows: chitosan oligosaccharide is added to PBS buffer and stirred to dissolve. Quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide are added. The mixture is placed at room temperature and stirred for 15 hours. After the reaction is completed, the mixture is dialyzed with pure water and dried to obtain functionalized chitosan oligosaccharide. The mass ratio of chitosan oligosaccharide, quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide is 1:1.2:0.6:0.7, and the amount of PBS buffer is 10 times the mass of chitosan oligosaccharide.

[0060] The preparation method of a waterproof and breathable polyurethane film is the same as that in Example 1.

[0061] Comparative Example 3

[0062] This comparative example provides a waterproof and breathable polyurethane film, comprising the following components by weight: 50 parts polyurethane resin, 4 parts chitosan oligosaccharide, 7 parts polystyrene, 2 parts mesoporous silica nanoparticles, 0.8 parts crosslinking agent, and 40 parts organic solvent; wherein the crosslinking agent is an aziridine crosslinking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 3:1.

[0063] The preparation method of a waterproof and breathable polyurethane film is the same as that in Example 1.

[0064] The moisture permeability, water pressure resistance, tensile strength, elongation at break, antibacterial properties, and flame retardancy of the polyurethane films tested in Examples 1 to 4 and Comparative Examples 1 to 3 were evaluated. Tensile strength and elongation at break were tested according to ASTM D-412 standards using a tensile testing machine at 23°C. Moisture permeability was tested according to ASTM E96-1995 BW standards, using a constant temperature and humidity chamber maintained at 23°C and 50% relative humidity. Water pressure resistance was tested according to JIS L1092B standards using a water pressure tester. Antibacterial properties were tested according to GB / T2591-2003 standards. Limiting oxygen index testing was conducted according to GB / T 2406.2-2008 standards. The results are shown in Table 1 below.

[0065] Table 1

[0066]

[0067] As shown in Table 1, the polyurethane films prepared in Examples 1 to 4 possess excellent mechanical properties, waterproof and breathable properties, antibacterial properties, and flame retardant properties. This indicates that the present invention achieves graft modification of chitosan oligosaccharides, resulting in a multifunctional waterproof and breathable polyurethane film. Compared with Comparative Examples 1 to 3, Example 1 demonstrates that the phosphonate groups and triphenyl quaternary phosphonium salt groups grafted onto chitosan oligosaccharides can work synergistically to impart excellent flame retardant properties to the polyurethane. Furthermore, the triphenyl quaternary phosphonium salt groups grafted onto chitosan oligosaccharides can overcome the defects caused by the grafting reaction, which leads to a reduction in free amino groups and a decrease in antibacterial rate. By working synergistically with chitosan molecules, the antibacterial properties of the polyurethane film are greatly enhanced.

[0068] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0069] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A waterproof and breathable polyurethane film, characterized by, The polyurethane film comprises the following components by weight: 40-50 parts of polyurethane resin, 3-4 parts of functionalized chitosan oligosaccharide, 6-8 parts of polystyrene, 1-2 parts of mesoporous silica nanoparticles, 0.5-0.8 parts of crosslinking agent, and 40-50 parts of organic solvent. The preparation method of the functionalized chitosan oligosaccharide is as follows: S1, dimethyl 2-hydroxyethyl phosphonate, N,N'-carbonyl diimidazole are added to acetonitrile, stirred at room temperature for 6-8h, then chitosan oligosaccharide aqueous solution is added, and the reaction is continued at a temperature of 40-50℃ for 10-12h, after the reaction is completed, the product is dialyzed with pure water and dried to obtain modified chitosan oligosaccharide; S2, the modified chitosan oligosaccharide is added to PBS buffer solution, stirred and dissolved, and quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide are added, stirred at room temperature for 12-15h, after the reaction is completed, the product is dialyzed with pure water and dried to obtain functionalized chitosan oligosaccharide; The preparation method of the quaternary phosphonium salt compound in step S2 is as follows: triphenylphosphine is added to N,N-dimethylformamide, heated to 115-120℃ under nitrogen protection, and 4-chlorobutyric acid is slowly added dropwise, after the dropwise addition is completed, the reaction is continued for 20-24h to obtain the quaternary phosphonium salt compound.

2. The waterproof and breathable polyurethane film according to claim 1, characterized in that, The mass ratio of chitosan oligosaccharide, dimethyl 2-hydroxyethyl phosphonate and N,N'-carbonyl diimidazole in step S1 is 1:0.2-0.3:0.3-0.

35.

3. The waterproof and breathable polyurethane film according to claim 1, characterized in that, The concentration of the chitosan oligosaccharide aqueous solution in step S1 is 8-10wt%.

4. The waterproof and breathable polyurethane film according to claim 1, wherein, The molar ratio of triphenylphosphine and 4-chlorobutyric acid is 1:1.1-1.

2.

5. The waterproof and breathable polyurethane film according to claim 1, wherein, The mass ratio of modified chitosan oligosaccharide, quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide in step S2 is 1:1.1-1.2:0.55-0.6:0.65-0.

7.

6. The waterproof and breathable polyurethane film according to claim 1, wherein, The crosslinking agent is aziridine crosslinking agent.

7. The waterproof and breathable polyurethane film according to claim 1, wherein The organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran with a mass ratio of 2-3:

1.

8. A process for the production of a waterproof, vapor-permeable polyurethane film as claimed in any one of claims 1 to 7, characterized in that, The preparation method comprises the following steps: according to the weight ratio, polystyrene and tetrahydrofuran are first mixed uniformly to obtain a mixed solution, polyurethane resin and N,N-dimethylformamide are then mixed uniformly, and functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and crosslinking agent are added, stirred at a temperature of 80-85℃ for 1.5-2h, the mixed solution is then added, and the stirring is continued for 20-30min, after cooling, the product is scraped onto release paper and dried in an oven to obtain a polyurethane film.

9. The method for preparing a waterproof and breathable polyurethane film according to claim 8, characterized in that, The drying temperature is 110-120℃, and the drying time is 8-10min.

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