Waterproof and breathable polyurethane film and preparation method thereof

Abstract

The invention 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 is prepared from the following components in parts by weight: 40 to 50 parts of polyurethane resin, 3 to 4 parts of functionalized chitosan oligosaccharide, 6 to 8 parts of polystyrene, 1 to 2 parts of mesoporous silica nanoparticles, 0.5 to 0.8 part of a cross-linking agent and 40 to 50 parts of an organic solvent, the polyurethane resin is used as a main component, the hydrophobic polystyrene, the mesoporous silica nanoparticles with the porous structure and the functional chitosan oligosaccharide are added, and the components are mutually crosslinked through the aziridine crosslinking agent to form a polyurethane film with a compact structure, so that the mechanical property and the waterproof and air-permeable properties of the polyurethane film are improved, and the waterproof and air-permeable properties of the polyurethane film are improved. And the antibacterial property and flame retardant property of the polyurethane film are greatly enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane films, and particularly relates to a waterproof and breathable polyurethane film and a preparation method thereof. Background Art

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

[0003] The Chinese patent application number 202310770952.0 discloses a catechol-grafted photosensitive chitosan oligosaccharide modified polyurethane film, its preparation method, and application. First, chitosan oligosaccharide and methacrylic anhydride are used as the main raw materials, and a methacrylic acylation reaction is used to synthesize a carbon-carbon double bond grafted photosensitive chitosan oligosaccharide; then, the chitosan oligosaccharide is reacted with 3,4-dihydroxybenzoic acid, and a catechol-grafted photosensitive chitosan oligosaccharide is synthesized by an EDC / NHS coupling reaction. Finally, the catechol-grafted photosensitive chitosan oligosaccharide modified polyurethane film is synthesized by mixing the prepared photocurable waterborne polyurethane and a photoinitiator through a photocuring reaction. This patent application has the following problems: 1. Chitosan oligosaccharides are rich in hydroxyl and amino groups, and have good water solubility, biocompatibility and antibacterial properties. While giving polyurethane films antibacterial effects, they also increase their hydrophilicity, resulting in a decrease in the waterproof performance of polyurethane films, limiting the application of chitosan oligosaccharides in waterproof polyurethane films.

[0004] 2. The antibacterial rate of the prepared polyurethane film against Staphylococcus aureus is only 36-55%; the protonated amino group on chitosan oligosaccharide is the key to its antibacterial activity. The amino group in its molecular structure serves as a reaction site, and carbon-carbon double bonds and catechol 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 grafting functional modification on chitosan oligosaccharide, the impact on antibacterial properties needs to be considered.

[0005] 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

[0006] The purpose of the present invention is to address the deficiencies in the prior art and provide a waterproof and breathable polyurethane film. The polyurethane film is mainly composed of a polyurethane resin, to which hydrophobic polystyrene, porous mesoporous silica nanoparticles and functional chitosan oligosaccharides are added. The components are cross-linked with each other using an aziridine cross-linking agent to form a densely structured polyurethane film. This not only improves the mechanical properties and waterproof and breathable properties of the polyurethane film, but also greatly enhances the antibacterial and flame retardant properties of the polyurethane film.

[0007] The technical solutions adopted by the present invention to achieve the above-mentioned purpose are: A waterproof and breathable polyurethane film comprises the following components in parts 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 a crosslinking agent, and 40-50 parts of an organic solvent.

[0008] Furthermore, the cross-linking agent is an aziridine cross-linking agent.

[0009] Furthermore, the organic solvent consists of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 2-3:1.

[0010] Furthermore, the preparation method of the functionalized chitosan oligosaccharide is: S1. Add 2-hydroxyethylphosphonic acid dimethyl ester and N,N'-carbonyldiimidazole to acetonitrile, place at room temperature, stir and react for 6-8 hours, then add chitosan oligosaccharide aqueous solution, continue to react at 40-50°C for 10-12 hours, after the reaction is completed, dialyze with purified water and dry to obtain modified chitosan oligosaccharide; S2. Add the modified chitosan oligosaccharide into 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 hours. After the reaction is completed, dialyze with pure water and dry to obtain functionalized chitosan oligosaccharide.

[0011] Furthermore, 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.

[0012] Furthermore, the concentration of the chitosan oligosaccharide aqueous solution in step S1 is 8-10 wt%.

[0013] Furthermore, the preparation method of the quaternary phosphonium salt compound in step S2 is: adding triphenylphosphine to N,N-dimethylformamide, heating to 115-120° C. under nitrogen protection, slowly adding 4-chlorobutyric acid dropwise, and continuing the reaction for 20-24 hours to obtain the quaternary phosphonium salt compound.

[0014] Furthermore, the molar ratio of triphenylphosphine to 4-chlorobutyric acid is 1:1.1-1.2.

[0015] Furthermore, 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.

[0016] The present invention also provides a method for preparing a waterproof and breathable polyurethane film, comprising the following steps: first, uniformly mixing polystyrene and tetrahydrofuran according to a weight ratio to obtain a mixed liquid; then, uniformly mixing a polyurethane resin and N,N-dimethylformamide; then, adding functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and a cross-linking agent; stirring at a temperature of 80-85°C for 1.5-2 hours; then, adding the mixed liquid; continuing to stir for 20-30 minutes; cooling, coating the mixture on a release paper, and drying the mixture in an oven to obtain a polyurethane film.

[0017] Furthermore, the drying temperature is 110-120° C., and the drying time is 8-10 minutes.

[0018] The present invention has the following beneficial effects: 1. The present invention uses chitosan oligosaccharide as a raw material, first reacts chitosan oligosaccharide with 2-hydroxyethyl dimethyl phosphonate, grafts hydrophobic and flame-retardant phosphonate groups onto the chitosan oligosaccharide to obtain modified chitosan oligosaccharide, then reacts the modified chitosan oligosaccharide with a quaternary phosphonium salt compound, and further grafts triphenyl quaternary phosphonium salt groups with flame-retardant and antibacterial effects onto the chitosan oligosaccharide to obtain functionalized chitosan oligosaccharide; the flame-retardant and antibacterial groups grafted onto the chitosan oligosaccharide prepared by the present invention greatly enhance its antibacterial and flame-retardant properties.

[0019] 2. The present invention uses functionalized chitosan oligosaccharide for the modification of polyurethane film. The phosphonate group and triphenyl quaternary phosphonium salt group grafted on the chitosan oligosaccharide can work synergistically to give the polyurethane good flame retardant properties. Moreover, the triphenyl quaternary phosphonium salt group grafted on the chitosan oligosaccharide can also overcome the defects of reducing the free amino groups in the chitosan oligosaccharide and reducing the antibacterial rate due to the grafting reaction, and work synergistically with the chitosan molecules, thereby greatly improving the antibacterial properties of the polyurethane film.

[0020] 3. The present invention uses polyurethane resin as the main component, adds hydrophobic polystyrene, porous mesoporous silica nanoparticles and functional chitosan oligosaccharides, and cross-links the components with each other through an aziridine cross-linking agent to form a densely structured polyurethane film, which not only improves the mechanical properties and waterproof and breathable properties of the polyurethane film, but also greatly enhances the antibacterial and flame retardant properties of the polyurethane film. DETAILED DESCRIPTION

[0021] In order to make the purpose, 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 combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] In the technical solution of the present invention, the chemical reagents used are all commercially available, among which polyurethane resin was purchased from Zhejiang Huafeng Synthetic Resin Co., Ltd., model JF-A-WV7020; mesoporous silica nanoparticles were purchased from Beijing Zhongke Keyou Technology Co., Ltd.; chitosan oligosaccharide (molecular weight 1500, deacetylation degree 90%); polystyrene CAS No. 9003-53-6; aziridine crosslinker CAS No. 64265-57-2; PBS buffer solution with a pH of 5, prepared from potassium dihydrogen phosphate and disodium hydrogen phosphate; 2-hydroxyethylphosphonic acid dimethyl ester CAS No. 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.

[0023] Example 1 This embodiment provides a waterproof and breathable polyurethane film, comprising the following components in parts by weight: 50 parts of polyurethane resin, 4 parts of functionalized chitosan oligosaccharide, 7 parts of polystyrene, 2 parts of mesoporous silica nanoparticles, 0.8 parts of a cross-linking agent, and 40 parts of an organic solvent; wherein the cross-linking agent is an aziridine cross-linking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 3:1.

[0024] The preparation method of functionalized chitosan oligosaccharide is as follows: S1. Add 2-hydroxyethylphosphonic acid dimethyl ester and N,N'-carbonyldiimidazole to acetonitrile, place it at room temperature, stir and react for 8 hours, then add chitosan oligosaccharide aqueous solution, continue to react at 50°C for 10 hours, after the reaction is completed, dialyze with pure water and dry to obtain modified chitosan oligosaccharide; wherein the mass ratio of chitosan oligosaccharide, 2-hydroxyethylphosphonic acid dimethyl ester and N,N'-carbonyldiimidazole is 1:0.3:0.35, and the concentration of chitosan oligosaccharide aqueous solution is 9wt%.

[0025] S2. Add the modified chitosan oligosaccharide to PBS buffer, stir and dissolve, add a quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride, and N-hydroxysuccinimide, place at room temperature, stir and react for 15 hours, and after the reaction is completed, dialyze with pure water and dry to obtain functionalized chitosan oligosaccharide; wherein 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 the modified chitosan oligosaccharide.

[0026] The preparation method of the quaternary phosphonium salt compound in step S2 is as follows: 20.0 g of triphenylphosphine is added to 400 mL of N,N-dimethylformamide, and the temperature is raised to 120 ° C. under nitrogen protection, and 10.3 g of 4-chlorobutyric acid is slowly added dropwise. After the dropwise addition, the reaction is continued for 24 hours. After the reaction is completed, the mixture is cooled, water and dichloromethane are added for extraction, and the organic phase is extracted again with water. The aqueous phase is 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 is 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).

[0027] This embodiment also provides a method for preparing a waterproof and breathable polyurethane film, comprising the following steps: first, polystyrene and tetrahydrofuran are uniformly mixed in a weight ratio to obtain a mixed liquid; then, polyurethane resin and N,N-dimethylformamide are uniformly mixed; then, functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and a cross-linking agent are added; the mixture is stirred at a temperature of 85°C for 1.5 hours; then, the mixed liquid is added and stirring is continued for 30 minutes; after cooling, the mixture is scraped 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 minutes.

[0028] Example 2 This embodiment provides a waterproof and breathable polyurethane film, comprising the following components in parts by weight: 45 parts of polyurethane resin, 3 parts of functionalized chitosan oligosaccharide, 8 parts of polystyrene, 1.5 parts of mesoporous silica nanoparticles, 0.6 parts of a cross-linking agent, and 45 parts of an organic solvent; wherein the cross-linking agent is an aziridine cross-linking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 2.5:1.

[0029] The preparation method of functionalized chitosan oligosaccharide is as follows: S1. Add 2-hydroxyethyl phosphonic acid dimethyl ester and N,N'-carbonyldiimidazole to acetonitrile, place it at room temperature, stir and react for 7 hours, then add chitosan oligosaccharide aqueous solution, continue to react at 40°C for 12 hours. After the reaction is completed, dialyze with pure water and dry to obtain modified chitosan oligosaccharide; wherein the mass ratio of chitosan oligosaccharide, 2-hydroxyethyl phosphonic acid dimethyl ester and N,N'-carbonyldiimidazole is 1:0.25:0.33, and the concentration of the chitosan oligosaccharide aqueous solution is 10wt%.

[0030] S2. Add the modified chitosan oligosaccharide to PBS buffer, stir and dissolve, add quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride, and N-hydroxysuccinimide, place at room temperature, stir and react for 13 hours, after the reaction is completed, dialyze with pure water and dry to obtain functionalized chitosan oligosaccharide; wherein, 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 the modified chitosan oligosaccharide.

[0031] This embodiment also provides a method for preparing a waterproof and breathable polyurethane film, comprising the following steps: first, polystyrene and tetrahydrofuran are uniformly mixed in a weight ratio to obtain a mixed liquid; further, polyurethane resin and N,N-dimethylformamide are uniformly mixed; functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and a cross-linking agent are added; the mixture is stirred at a temperature of 80°C for 2 hours; the mixed liquid is then added; stirring is continued for 20 minutes; after cooling, the mixture is scraped onto release paper; and the mixture is placed in an oven for drying to obtain a polyurethane film; wherein the drying temperature is 110°C and the drying time is 10 minutes.

[0032] Example 3 This embodiment provides a waterproof and breathable polyurethane film, comprising the following components in parts by weight: 40 parts of polyurethane resin, 3.5 parts of functionalized chitosan oligosaccharide, 6 parts of polystyrene, 1 part of mesoporous silica nanoparticles, 0.5 parts of a cross-linking agent, and 50 parts of an organic solvent; wherein the cross-linking agent is an aziridine cross-linking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 2:1.

[0033] The preparation method of functionalized chitosan oligosaccharide is as follows: S1. Add 2-hydroxyethylphosphonic acid dimethyl ester and N,N'-carbonyldiimidazole to acetonitrile, place it at room temperature, stir and react for 6 hours, then add chitosan oligosaccharide aqueous solution, continue to react at 45°C for 11 hours, after the reaction is completed, dialyze with pure water and dry to obtain modified chitosan oligosaccharide; wherein the mass ratio of chitosan oligosaccharide, 2-hydroxyethylphosphonic acid dimethyl ester and N,N'-carbonyldiimidazole is 1:0.2:0.3, and the concentration of chitosan oligosaccharide aqueous solution is 8wt%.

[0034] S2. Add the modified chitosan oligosaccharide to PBS buffer, stir and dissolve, add quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride, and N-hydroxysuccinimide, place at room temperature, stir and react for 12 hours, after the reaction is completed, dialyze with pure water and dry to obtain functionalized chitosan oligosaccharide; wherein, 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 the modified chitosan oligosaccharide.

[0035] This embodiment also provides a method for preparing a waterproof and breathable polyurethane film, comprising the following steps: first, polystyrene and tetrahydrofuran are uniformly mixed in a weight ratio to obtain a mixed liquid; further, polyurethane resin and N,N-dimethylformamide are uniformly mixed; functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and a cross-linking agent are added; the mixture is stirred at a temperature of 83°C for 1.8 hours; the mixed liquid is then added; stirring is continued for 25 minutes; after cooling, the mixture is scraped 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 minutes.

[0036] Example 4 This embodiment provides a waterproof and breathable polyurethane film, comprising the following components in parts by weight: 50 parts of polyurethane resin, 3 parts of functionalized chitosan oligosaccharide, 6 parts of polystyrene, 1.5 parts of mesoporous silica nanoparticles, 0.7 parts of a cross-linking agent, and 45 parts of an organic solvent; wherein the cross-linking agent is an aziridine cross-linking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 3:1.

[0037] The preparation method of functionalized chitosan oligosaccharide is as follows: S1, the same as step S1 in embodiment 2; S2, the same as step S2 in embodiment 1; This embodiment also provides a method for preparing a waterproof and breathable polyurethane film, comprising the following steps: first, polystyrene and tetrahydrofuran are uniformly mixed in a weight ratio to obtain a mixed liquid; further, polyurethane resin and N,N-dimethylformamide are uniformly mixed; functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and a cross-linking agent are added; the mixture is stirred at a temperature of 85°C for 2 hours; the mixed liquid is then added; stirring is continued for 20 minutes; after cooling, the mixture is scraped 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.

[0038] Comparative Example 1 This comparative example provides a waterproof and breathable polyurethane film, comprising the following components in parts by weight: 50 parts of polyurethane resin, 4 parts of modified chitosan oligosaccharide, 7 parts of polystyrene, 2 parts of mesoporous silica nanoparticles, 0.8 parts of a cross-linking agent, and 40 parts of an organic solvent; wherein the cross-linking agent is an aziridine cross-linking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 3:1.

[0039] The preparation method of modified chitosan oligosaccharide is the same as step S1 of Example 1.

[0040] The preparation method of a waterproof and breathable polyurethane film is the same as that of Example 1.

[0041] Comparative Example 2 This comparative example provides a waterproof and breathable polyurethane film, comprising the following components in parts by weight: 50 parts of polyurethane resin, 4 parts of functionalized chitosan oligosaccharide, 7 parts of polystyrene, 2 parts of mesoporous silica nanoparticles, 0.8 parts of a cross-linking agent, and 40 parts of an organic solvent; wherein the cross-linking agent is an aziridine cross-linking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 3:1.

[0042] The preparation method of functionalized chitosan oligosaccharide comprises the following steps: adding chitosan oligosaccharide to PBS buffer solution, stirring and dissolving, adding a quaternary phosphonium salt compound, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide, placing the mixture at room temperature, stirring and reacting for 15 hours, and after completion of the reaction, dialyzing with pure water and drying to obtain functionalized chitosan oligosaccharide; wherein 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 solution used is 10 times the mass of chitosan oligosaccharide.

[0043] The preparation method of a waterproof and breathable polyurethane film is the same as that of Example 1.

[0044] Comparative Example 3 This comparative example provides a waterproof and breathable polyurethane film, comprising the following components in parts by weight: 50 parts of polyurethane resin, 4 parts of chitosan oligosaccharide, 7 parts of polystyrene, 2 parts of mesoporous silica nanoparticles, 0.8 parts of a cross-linking agent, and 40 parts of an organic solvent; wherein the cross-linking agent is an aziridine cross-linking agent; and the organic solvent is composed of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 3:1.

[0045] The preparation method of a waterproof and breathable polyurethane film is the same as that of Example 1.

[0046] The polyurethane films of Examples 1 to 4 and Comparative Examples 1 to 3 were tested for moisture permeability, water pressure resistance, tensile strength, elongation at break, antibacterial properties, and flame retardancy. The tensile strength and elongation at break were tested using a tensile testing machine at 23° C. in accordance with ASTM D-412. The moisture permeability was tested using a constant temperature and humidity chamber maintained at 23° C. and 50% relative humidity in accordance with ASTM E96-1995 BW. The water pressure resistance was tested using a water pressure tester in accordance with JIS L1092B. The antibacterial properties were tested in accordance with GB / T 2591-2003. The limiting oxygen index test was conducted in accordance with GB / T 2406.2-2008. The results are shown in Table 1 below.

[0047] Table 1 As can be seen from the results in Table 1, the polyurethane films prepared in Examples 1 to 4 have good mechanical properties, waterproof and breathable properties, antibacterial properties and flame retardant properties, indicating that the present invention realizes the grafting modification of chitosan oligosaccharides and can obtain a multifunctional waterproof and breathable polyurethane film; by comparing Example 1 with Comparative Examples 1 to 3, it can be shown that the phosphonate group and the triphenyl quaternary phosphonium salt group grafted on the chitosan oligosaccharide can work synergistically to give the polyurethane good flame retardant properties, and the triphenyl quaternary phosphonium salt group grafted on the chitosan oligosaccharide can also overcome the defects of the grafting reaction, which leads to a reduction in the free amino group in the chitosan oligosaccharide and a decrease in the antibacterial rate, and synergizes with the chitosan molecules, thereby greatly improving the antibacterial properties of the polyurethane film.

[0048] It should be noted that, in this document, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0049] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A waterproof and breathable polyurethane film, characterized in that: 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 a crosslinking agent, and 40-50 parts of an organic solvent; The preparation method of the functionalized chitosan oligosaccharide is as follows: S1. Add 2-hydroxyethylphosphonic acid dimethyl ester and N,N'-carbonyldiimidazole to acetonitrile, place at room temperature, stir and react for 6-8 hours, then add chitosan oligosaccharide aqueous solution, continue to react at 40-50°C for 10-12 hours, after the reaction is completed, dialyze with purified water and dry to obtain modified chitosan oligosaccharide; S2. Add the modified chitosan oligosaccharide into 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 hours. After the reaction is completed, dialyze with pure water and dry to obtain functionalized chitosan oligosaccharide.

2. The waterproof and breathable polyurethane film according to claim 1, characterized in that: The mass ratio of chitosan oligosaccharide, dimethyl 2-hydroxyethylphosphonate, and N,N'-carbonyldiimidazole 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, characterized in that: The preparation method of the quaternary phosphonium salt compound in step S2 is as follows: triphenylphosphine is added to N,N-dimethylformamide, the temperature is raised to 115-120° C. under nitrogen protection, 4-chlorobutyric acid is slowly added dropwise, and the reaction is continued for 20-24 hours to obtain the quaternary phosphonium salt compound.

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

2.

6. The waterproof and breathable polyurethane film according to claim 1, characterized in that: The mass ratio of the modified chitosan oligosaccharide, the 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.

7. The waterproof and breathable polyurethane film according to claim 1, characterized in that: The cross-linking agent is an aziridine cross-linking agent.

8. The waterproof and breathable polyurethane film according to claim 1, characterized in that: The organic solvent consists of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 2-3:

1.

9. A method for preparing a waterproof and breathable polyurethane film according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: firstly, uniformly mixing polystyrene and tetrahydrofuran according to a weight ratio to obtain a mixed liquid; separately, uniformly mixing a polyurethane resin and N,N-dimethylformamide; then, adding functionalized chitosan oligosaccharide, mesoporous silica nanoparticles and a crosslinking agent; stirring at a temperature of 80-85°C for 1.5-2 hours; then, adding the mixed liquid, continuing to stir for 20-30 minutes; cooling, coating the mixture on a release paper, and drying the mixture in an oven to obtain a polyurethane film.

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

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